Geologic Framework for the National Assessment of 

Carbon Dioxide Storage Resources─U.S. Gulf Coast

By Tina L. Roberts-Ashby, Sean T. Brennan, Marc L. Buursink, Jacob A. Covault, William H. Craddock, 

Ronald M. Drake II, Matthew D. Merrill, Ernie R. Slucher, Peter D. Warwick, Madalyn S. Blondes, Mayur A. Gosai, 

Philip A. Freeman, Steven M. Cahan, Christina A. DeVera, and Celeste D. Lohr

Chapter H of

Geologic Framework for the National Assessment of Carbon Dioxide Storage Resources

Edited by Peter D. Warwick and Margo D. Corum

Open-File Report 2012–1024–H

U.S. Department of the Interior

U.S. Geological Survey
ii

U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014

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Suggested citation:

Roberts-Ashby, T.L., Brennan, S.T., Buursink, M.L., Covault, J.A., Craddock, W.H., Drake, R.M., II, Merrill, M.D., 

Slucher, E.R., Warwick, P.D., Blondes, M.S., Gosai, M.A., Freeman, P.A., Cahan, S.M., DeVera, C.A., and Lohr, C.D., 

2014, Geologic framework for the national assessment of carbon dioxide storage resources—U.S. Gulf Coast, chap. 

H of Warwick, P.D., and Corum, M.D., eds., Geologic framework for the national assessment of carbon dioxide 

storage resources: U.S. Geological Survey Open-File Report 2012–1024–H, 77 p., 

http://dx.doi.org/10.3133/ofr20121024h.

ISSN 2331-1258 (online)

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report.
iii

Editors’ Preface

By Peter D. Warwick and Margo D. Corum

The 2007 Energy Independence and Security Act (Public Law 110–140) directs the U.S. 

Geological Survey (USGS) to conduct a national assessment of potential geologic storage resources for 

carbon dioxide (CO2) and to consult with other Federal and State agencies to locate the pertinent 

geological data needed for the assessment. The geologic sequestration of CO2 is one possible way to

mitigate its effects on climate change.

The methodology that is being used by the USGS for the assessment was described by Brennan 

and others (2010), who revised the methodology by Burruss and others (2009) according to comments 

from peer reviewers, members of the public, and experts on an external panel. The assessment 

methodology is non-economic and is intended to be used at regional to subbasinal scales. 

The operational unit of the assessment is a storage assessment unit (SAU) composed of a porous 

storage formation with fluid flow and an overlying fine-grained sealing unit. Assessments are conducted 

at the SAU level and are aggregated to basinal and regional results. SAUs have a minimum depth of 3,000 

feet (ft), which ensures that the CO2 is in a supercritical state (and thus occupies less pore space than a 

gas). Standard SAUs have a maximum depth of 13,000 ft below the surface, a depth accessible with 

average injection pipeline pressures (Burruss and others, 2009; Brennan and others, 2010). Where 

geologic conditions favor CO2 storage below 13,000 ft, an additional deep SAU is assessed. 

The assessments are also constrained by the occurrence of relatively fresh formation water. 

Specifically, any formation water having a salinity less than 10,000 milligrams per liter (mg/L) total 

dissolved solids (TDS), regardless of depth, has the potential to be used as a potable water supply (U.S. 

Environmental Protection Agency, 2009). The U.S. Environmental Protection Agency (2008) has 

proposed the limit of 10,000 mg/L TDS for injection of CO2. Therefore, the potential storage resources 

for CO2 in formations where formation waters have salinities less than 10,000 mg/L TDS are not assessed 

(Brennan and others, 2010). 

This report series contains geologic descriptions of each SAU identified within the assessed basins 

and focuses on the particular characteristics specified in the methodology that influence the potential CO2

storage resource. Although assessment results are not contained in these reports, the geologic framework 

information will be used to calculate a statistical Monte Carlo-based distribution of potential storage space 

in the various SAUs following Brennan and others (2010). Figures in this report series show SAU 

boundaries and cell maps of well penetrations through the sealing unit into the top of the storage 

formation. Wells sharing the same well borehole are treated as a single penetration. Cell maps show the 

number of penetrating wells within one square mile and are derived from interpretations of incompletely 

attributed well data (IHS Energy Group, 2011; and other data as available), a digital compilation that is 

known not to include all drilling. The USGS does not expect to know the location of all wells and cannot 

guarantee the amount of drilling through specific formations in any given cell shown on cell maps.
iv

References Cited

Brennan, S.T., Burruss, R.C., Merrill, M.D., Freeman, P.A., and Ruppert, L.F., 2010, A probabilistic 

assessment methodology for the evaluation of geologic carbon dioxide storage: U.S. Geological Survey 

Open-File Report 2010–1127, 31 p., accessed March 22, 2011, at http://pubs.usgs.gov/of/2010/1127/. 

Burruss, R.C., Brennan, S.T., Freeman, P.A., Merrill, M.D., Ruppert, L.F., Becker, M.F., Herkelrath, 

W.N., Kharaka, Y.K., Neuzil, C.E., Swanson, S.M., Cook, T.A., Klett, T.R., Nelson, P.H., and Schenk, 

C.J., 2009, Development of a probabilistic assessment methodology for evaluation of carbon dioxide 

storage: U.S. Geological Survey Open-File Report 2009–1035, 81 p., accessed March 22, 2011, at 

http://pubs.usgs.gov/of/2009/1035/. 

IHS Energy Group, 2011, ENERDEQ U.S. well data: IHS Energy Group, online database available from 

IHS Energy Group, 15 Inverness Way East, D205, Englewood, CO 80112, U.S.A., accessed January 

20, 2011, at http://energy.ihs.com/. 

U.S. Environmental Protection Agency, 2008, Federal requirements under the underground injection 

control (UIC) program for carbon dioxide (CO2) geologic sequestration (GS) wells: Washington, D.C., 

U.S. Environmental Protection Agency, proposed rule, accessed March 23, 2011, at 

http://www.epa.gov/fedrgstr/EPA-WATER/2008/July/Day-25/w16626.htm.

U.S. Environmental Protection Agency, 2009, Safe Drinking Water Act (SDWA): Washington, D.C., 

U.S. Environmental Protection Agency Web site, accessed January 14, 2009, at 

http://www.epa.gov/ogwdw/sdwa/index.html. 
v

Contents

Editors’ Preface ............................................................................................................................................................. iii

References Cited........................................................................................................................................................... iv

Abstract ..........................................................................................................................................................................1

Introduction.....................................................................................................................................................................1

Norphlet Formation SAU C50490101 and Norphlet Formation Deep SAU C50490102 ...............................................11

Smackover Formation SAU C50490103 and Smackover Formation Deep SAU C50490104.......................................14

Haynesville Formation SAU C50490105 and Haynesville Formation Deep SAU C50490106......................................17

Sligo and Hosston Formations and Cotton Valley Group SAU C50490107 and Sligo and Hosston Formations and 

Cotton Valley Group Deep SAU C50490108................................................................................................................20

Knowles and Winn Limestones and Calvin Sandstone SAU C50490109.....................................................................24

Rodessa Formation and James Limestone SAU C50490110 and Rodessa Formation and James Limestone Deep 

SAU C50490111...........................................................................................................................................................26

Fredericksburg Group and Rusk Formation SAU C50490112......................................................................................29

Edwards, Glen Rose, and James Limestones SAU C50490113 ..................................................................................29

Washita and Fredericksburg Groups, Rusk Formation, and James Limestone SAU C50490114 ................................29

Washita and Fredericksburg Groups, Rusk Formation, and James Limestone Deep SAU C50490115.......................29

Fredericksburg Group and Rusk Formation SAU C50490112......................................................................................31

Edwards, Glen Rose, and James Limestones SAU C50490113 ..................................................................................34

Washita and Fredericksburg Groups, Rusk Formation, and James Limestone SAU C50490114 and Washita and 

Fredericksburg Groups, Rusk Formation, and James Limestone Deep SAU C50490115............................................36

Tuscaloosa and Woodbine Formations SAU C50490116 ............................................................................................38

Navarro, Taylor, and Austin Groups SAU C50490117 .................................................................................................40

Carrizo Sand and Wilcox Group SAU C50470118 .......................................................................................................43

Queen City Sand SAU C50470119 ..............................................................................................................................46

Sparta Sand SAU C50470120......................................................................................................................................48

Yegua and Cockfield Formations SAU C50470121......................................................................................................50

Frio and Vicksburg Formations SAU C50470122.........................................................................................................53

Lower Miocene I SAU C50470123, Lower Miocene II SAU C50470124, Middle Miocene SAU C50470125, and 

Upper Miocene SAU C50470126 .................................................................................................................................56

Tertiary Slope and Basin Floor SAU C50470127 .........................................................................................................63

Acknowledgments ........................................................................................................................................................65

References Cited..........................................................................................................................................................65

Figures

Figure 1. Geologic map of the U.S. Gulf Coast study area within the southern U.S. Major structural features 

adapted from Ewing and Lopez (1991) and Galloway (2011). In the inset on the lower left, area in red is the U.S. 

Gulf Coast study area.....................................................................................................................................................5

Figure 2A. Main stratigraphic column for the U.S. Gulf Coast study area. Wavy lines indicate unconformable 

contacts, and gray areas represent unconformities. Adapted from Salvador and Quezada-Muñeton (1991), Dubiel 

and others (2007a), Warwick and others (2007), and Mancini and others (2008b). Ls = Limestone; Fm = Formation; 

Mbr = Member................................................................................................................................................................6
vi

Figure 2B. Stratigraphic column displaying the east-west distribution of the Upper Jurassic and Cretaceous 

geologic units within the U.S. Gulf Coast study area. Storage assessment units consist of a reservoir (red) and 

regional seal (blue). Wavy lines indicate unconformable contacts, and gray areas represent unconformities. Adapted 

from Nehring (1991), Salvador and Quezada-Muñeton (1991), Goldhammer and Johnson (2001), Witrock and others 

(2003), Sweezey and Sullivan (2004), Mancini and Puckett (2005), Warwick and others (2007), Mancini and others 

(2008b), Valentine and Dennen (2012), and Walker and others (2012) .........................................................................7

Figure 2C. Stratigraphic column displaying the east-west distribution of the Upper Cretaceous and lower Tertiary 

rocks within the U.S. Gulf Coast study area. Storage assessment units consist of a reservoir (red) and regional seal 

(blue). Wavy lines indicate unconformable contacts. Adapted from Salvador and Quezada-Muñeton (1991), Warwick 

and others (2007), and Mancini and others (2008b). Fm = Formation............................................................................8

Figure 2D. Stratigraphic column displaying the east-west distribution of the Tertiary rocks within the U.S. Gulf Coast 

study area—Part 1. Storage assessment units consist of a reservoir (red) and regional seal (blue). Wavy lines 

indicate unconformable contacts. Adapted from Salvador and Quezada-Muñeton (1991), Galloway and others (1994), 

Lawless and others (1997), Warwick and others (1997, 2007), Witrock and others (2003), Dubiel and others (2007a), 

and Valentine and Dennen (2012), Walker and others (2012). Fm = Formation ............................................................9

Figure 2E. Stratigraphic column displaying the east-west distribution of the Tertiary rocks within the U.S. Gulf Coast 

study area—Part 2. Storage assessment units consist of a reservoir (red) and regional seal (blue). Wavy lines 

indicate unconformable contacts. Adapted from Dubiel and others (2007a), Warwick and others (2007), and Mancini 

and others (2008b).......................................................................................................................................................10

Figure 3. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Norphlet Formation 

and Norphlet Formation Deep SAUs in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells 

derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir-formation top. 13

Figure 4. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Smackover 

Formation and Smackover Formation Deep SAUs in the U.S. Gulf Coast. Grid cells (one square mile) represent 

counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoirformation top ................................................................................................................................................................16

Figure 5. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Haynesville 

Formation and Haynesville Formation Deep SAUs in the U.S. Gulf Coast. Grid cells (one square mile) represent 

counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir 

formation top ................................................................................................................................................................19

Figure 6. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Sligo and Hosston 

Formations and Cotton Valley Group and Sligo and Hosston Formations and Cotton Valley Group Deep SAUs in the 

U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS 

Energy Group, 2011) that have penetrated the reservoir formation top........................................................................23

Figure 7. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Knowles and 

Winn Limestones and Calvin Sandstone SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts

of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir 

formation top ................................................................................................................................................................25

Figure 8. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Rodessa 

Formation and James Limestone and Rodessa Formation and James Limestone Deep SAUs in the U.S. Gulf Coast. 

Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 

2011) that have penetrated the reservoir formation top................................................................................................28

Figure 9. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Fredericksburg 

Group and Rusk Formation SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of 

wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir 

formation top ................................................................................................................................................................33
vii

Figure 10. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Edwards, Glen 

Rose, and James Limestones SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of 

wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir 

formation top ................................................................................................................................................................35

Figure 11. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Washita and 

Fredericksburg Groups, Rusk Formation, and James Limestone and Washita and Fredericksburg Groups, Rusk 

Formation, and James Limestone Deep SAUs in the U.S. Gulf Coast. Grid cells (one square mile) represent counts 

of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir 

formation top ................................................................................................................................................................37

Figure 12. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Woodbine and 

Tuscaloosa Formations SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived 

from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation top..............39

Figure 13. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Navarro, Taylor, 

and Austin Groups SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from 

ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation top ......................42

Figure 14. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Carrizo Sand and 

Wilcox Group SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from 

ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation top ......................45

Figure 15. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Queen City Sand 

SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well 

database (IHS Energy Group, 2011) that have penetrated the reservoir formation top................................................47

Figure 16. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Sparta Sand SAU 

in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database 

(IHS Energy Group, 2011) that have penetrated the reservoir formation top................................................................49

Figure 17. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Yegua and 

Cockfield Formations SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from 

ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation top ......................52

Figure 18. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Frio and Vicksburg 

Formations SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from 

ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation top ......................55

Figure 19. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Lower Miocene I 

SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well 

database (IHS Energy Group, 2011) that have penetrated the reservoir formation top................................................59

Figure 20. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Lower Miocene II 

SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well 

database (IHS Energy Group, 2011) that have penetrated the reservoir formation top................................................60

Figure 21. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Middle Miocene 

SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well 

database (IHS Energy Group, 2011) that have penetrated the reservoir formation top................................................61

Figure 22. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Upper Miocene 

SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well 

database (IHS Energy Group, 2011) that have penetrated the reservoir formation top................................................62

Figure 23. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Tertiary Slope and 

Basin Floor SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from 

ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation top ......................64
viii

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 0.09290 square meter (m2)

square foot (ft2) 0.00002296 acre 

square mile (mi2) 2.59 square kilometer (km2)

Volume

barrel (bbl), (petroleum, 1 barrel=42 gal) 0.1590 cubic meter (m3) 

cubic foot (ft3) 0.02832 cubic meter (m3) 

1,000 cubic feet (MCF) 28.32 cubic meter (m3)

cubic meter (m3) 6.290 barrel (petroleum, 1 barrel = 42 gal)

Acronyms and Abbreviations

CO2 carbon dioxide

EPA U.S. Environmental Protection Agency

mD millidarcy

mg/L milligrams per liter

MMBO million barrels of oil

SAU storage assessment unit

TDS total dissolved solids

USGS U.S. Geological Survey
1

Geologic Framework for the National Assessment of 

Carbon Dioxide Storage Resources─U.S. Gulf Coast

By Tina L. Roberts-Ashby, Sean T. Brennan, Marc L. Buursink, Jacob A. Covault1, William H. Craddock, 

Ronald M. Drake II, Matthew D. Merrill, Ernie R. Slucher, Peter D. Warwick, Madalyn S. Blondes, Mayur A. Gosai, 

Philip A. Freeman, Steven M. Cahan, Christina A. DeVera, and Celeste D. Lohr

Abstract

This report presents 27 storage assessment units (SAUs) within the United States (U.S.) Gulf 

Coast. The U.S. Gulf Coast contains a regionally extensive, thick succession of clastics, carbonates, salts, 

and other evaporites that were deposited in a highly cyclic depositional environment that was subjected to 

a fluctuating siliciclastic sediment supply and transgressive and regressive sea levels. At least nine major 

depositional packages contain porous strata that are potentially suitable for geologic carbon dioxide (CO2) 

sequestration within the region. For each SAU identified within these packages, the areal distribution of 

porous rock that is suitable for geologic CO2 sequestration is discussed, along with a description of the 

geologic characteristics that influence the potential CO2 storage volume and reservoir performance. These 

characteristics include reservoir depth, gross thickness, net-porous thickness, porosity, permeability, and 

groundwater salinity. Additionally, a characterization of the overlying regional seal for each SAU is 

presented. On a case-by-case basis, strategies for estimating the pore volume existing within structurally 

and (or) stratigraphically closed traps are also presented. Geologic information presented in this report has 

been employed to calculate potential storage capacities for CO2 sequestration in the SAUs that are 

assessed herein, although complete assessment results are not contained in this report.

Introduction

The area assessed within the Gulf of Mexico Basin and the surrounding region is identified in this 

paper as the United States (U.S.) Gulf Coast, which encompasses an area of approximately 148,049,000 

acres and extends across southern, central, and eastern Texas; Louisiana; eastern and southern Arkansas; 

southeastern Missouri; southwestern Kentucky; western Tennessee; central and southern Mississippi; 

southern Alabama; the Florida panhandle; and the southwestern corner of Georgia (fig. 1). The U.S. Gulf 

Coast is a major petroleum-producing region of the United States, and includes the onshore portion of 

basins within the Gulf of Mexico down to the State-water lines, which mark the southern boundary of the 

Gulf Coast region study area. Study area boundaries are also delineated by the U.S.-Mexico international 

border (southwestern boundary); the updip limit of Cretaceous sedimentary rocks (northern boundary); 

and faults associated with the Ouachita orogenic belt (western boundary), the Ouachita Mountains 

(northern boundary), and the Appalachian Mountains (northeastern boundary; fig. 1). Sea-level 

oscillations had a major impact on sedimentation and the types of depositional environments that existed 

within the region. Additionally, fluctuations in clastic sediment supply associated with uplift and erosion 

of nearby mountain ranges, fluctuating channels and drainage systems, and changes in basin structure 

greatly affected sedimentation within the region, including the presence or absence and extent of 

carbonate environments.

1 Current address: Chevron Energy Technology Company, Clastic Stratigraphy R&D, Houston, Texas 77002, USA
2

The Gulf of Mexico Basin and surrounding region within the U.S. Gulf Coast were originally 

formed as a result of crustal extension and expansion of the seafloor associated with the breakup of 

Pangea during Mesozoic time (Sawyer and others, 1991). The main depocenter of the Gulf Coast region, 

which is thought to underlie the southern Louisiana coastal plain and adjacent continental shelf, contains 

as much as 65,600 feet (ft) of rock that accumulated from the Jurassic through the Holocene (Galloway, 

2011). The strata within the U.S. Gulf Coast is generally composed of sedimentary rocks that were largely 

deposited over a thick sequence of salt (Louann Salt) and other evaporites, especially in the northern and 

southern regions (Salvador, 1991a). The positions and trends of salt structures, which are dependent upon 

the basement faults together with gravity tectonic structures, affected sediment supply and distribution 

within the basins and had a major impact on the generation and mobilization of hydrocarbons within the 

region (Galloway, 2011).

The strata within the area of the U.S. Gulf Coast (figs. 2A, 2B, 2C, 2D, and 2E) can be divided into 

nine major depositional packages, which are composed of 28 composite depositional episodes, as outlined 

by Galloway (2011), and are separated by local and regional unconformities and (or) maximum-flooding 

disconformities. These depositional packages are useful for identifying prospective reservoir intervals and 

regional seals and are from oldest to youngest (1) a tectonostratigraphic megasequence of salts and other 

evaporites, siliclastics, and carbonates that includes the Upper Jurassic to Lower Cretaceous Louann Salt, 

Smackover Formation, and Cotton Valley Group; (2) pro-delta and fluvial-deltaic deposits of the Lower 

Cretaceous Hosston Formation, which was deposited following the cessation of seafloor spreading in the 

Gulf; (3) Lower Cretaceous carbonate-dominated sedimentation on a reef-rimmed carbonate margin; (4)

Upper Cretaceous Tuscaloosa and Woodbine Formations deltaic deposits associated with prograding, 

rejuvenated clastic systems; (5) Upper Cretaceous carbonate, sandstone, basinal marl, and mudrock

deposits that created a ramp-like shelf margin; (6) Paleocene-Eocene-Oligocene siliciclastic, volcanic ash, 

and volcaniclastic deposits associated with a prograding shelf and slope; (7) increased sediment supply 

leading to an extensive continental-margin progradation during the Miocene, in conjunction with a shift in 

the basin’s depocenter from the northwestern to the northeastern margin and the rejuvenation of the 

Appalachian and Cumberland Plateau uplands; (8) early Pliocene multi-sequence deposition associated 

with rapid, glacio-eustatic sea-level fluctuations; and (9) upper Pliocene and Quaternary fluvialdominated delta and subjacent slope-apron-system deposits, as well as canyon excavation resulting from 

glacial meltwater surges (Salvador, 1991a; Dyman and Condon, 2006; Galloway, 2011).

The Gulf Coast is one of the most productive and heavily explored petroleum-producing regions 

in the United States, with basins that contain numerous mature oil and gas fields. Recently completed 

geologic assessments of undiscovered oil and gas resources conducted by the U.S. Geological Survey 

(USGS) present the extensive history of hydrocarbon production in the U.S. Gulf Coast region (Schenk 

and Viger, 1995a,b; USGS Cotton Valley Assessment Team, 2003; USGS Travis Peak-Hosston 

Assessment Team, 2003; USGS Navarro and Taylor Groups Assessment Team, 2004, 2006; USGS Gulf 

Coast Region Assessment Team, 2006; Dubiel and others, 2007a, 2011, 2012; Pitman and others, 2007; 

Pearson and others, 2011). The USGS estimates that approximately 1,482 million barrels of oil (MMBO), 

153,290 billion cubic feet of gas, and approximately 5,168 million barrels of natural gas liquids remain 

undiscovered in the area of the Gulf Coast that was assessed in this report (USGS Cotton Valley 

Assessment Team, 2003; USGS Travis Peak-Hosston Assessment Team, 2003; USGS Navarro and 

Taylor Groups Assessment Team, 2004; Dubiel and others, 2007a, 2011; Pitman and others, 2007). 

Because the Gulf Coast has been one of the most productive regions within the U.S., pore volumes

associated with existing and depleted oil and gas fields may be available for the purpose of geologic CO2

sequestration, with the additional possibility of uncharged traps that have yet to be discovered. Nonpetroleum-producing saline aquifers occur throughout the region as well, with total dissolved solid (TDS) 

concentrations exceeding 10,000 milligrams per liter (mg/L). These aquifers can provide additional

porous storage space for CO2 sequestration. 

Numerous geochemically distinct hydrocarbon systems in the U.S. Gulf Coast are associated with 

unique source rocks and are confined to discrete stratigraphic intervals (Schenk and Viger, 1995a,b; 
3

USGS Cotton Valley Assessment Team, 2003; USGS Travis Peak-Hosston Assessment Team, 2003; 

USGS Navarro and Taylor Groups Assessment Team, 2004, 2006; USGS Gulf Coast Region Assessment 

Team, 2006; Pitman and others, 2007; Dubiel and others, 2011, 2012; Pearson and others, 2011). This 

stratigraphic confinement of hydrocarbon systems is important to the potential for geologic CO2

sequestration because it suggests the presence of several regional sealing units that are internal to basin

fill within the region. The geographic extent of “regional” can vary from basin to basin within the United 

States. Within the U.S. Gulf Coast, “regional” is considered to be an area that typically extends across two 

or more States. Regional seals are essential components to CO2 storage sites, and their likely presence in 

hydrocarbon systems of the U.S. Gulf Coast suggests the potential for containment of CO2 over long 

periods of geologic time (that is, millennia), and a low risk of leakage from storage sites into overlying 

sources of drinking water or into the atmosphere (Wilson and others, 2003).

Multiple geologic units within the U.S. Gulf Coast meet the USGS criteria for conducting a 

regional assessment for CO2 storage capacity and are confined to the first seven previously discussed 

depositional packages. The remaining two depositional packages (numbered 8 and 9), where they meet 

the USGS criteria, are for the most part present in Federal offshore waters and are the purview of the 

Bureau of Ocean Energy Management. It should be noted that each storage assessment unit (SAU) 

assigned to these geologic units has varying extent across the U.S. Gulf Coast region. The USGS-assessed 

reservoir units include (1) Upper Jurassic Norphlet Formation SAUs, (2) Upper Jurassic Smackover 

Formation SAUs, (3) Upper Jurassic Haynesville Formation SAUs, (4) Lower Cretaceous Sligo and 

Hosston Formations and Upper Jurassic and Lower Cretaceous Cotton Valley Group SAUs, (5) Lower 

Cretaceous Knowles and Winn Limestones and Calvin Sandstone SAU, (6) Lower Cretaceous Rodessa 

Formation and James Limestone SAUs, (7) Lower Cretaceous Fredericksburg Group and Rusk Formation 

SAU, (8) Lower Cretaceous Edwards, Glen Rose, and James Limestones SAU, (9) Lower Cretaceous 

Washita and Fredericksburg Groups, Rusk Formation, and James Limestone SAUs, (10) Upper 

Cretaceous Tuscaloosa and Woodbine Formations SAU, (11) Upper Cretaceous Navarro, Taylor, and 

Austin Groups SAU, (12) Paleogene Carrizo Sand and Wilcox Group SAU, (13) Paleogene Queen City 

Sand SAU, (14) Paleogene Sparta Sand SAU, (15) Paleogene Yegua and Cockfield Formations SAU, (16) 

Paleogene Frio and Vicksburg Formations SAU, (17) Neogene Lower Miocene I and II, Middle, and 

Upper Miocene SAUs, and (18) Paleogene and Neogene Tertiary slope and basin floor SAU (figs. 2A, 2B, 

2C, 2D, and 2E). 

In the following sections, the depositional setting, distribution, and stratigraphy of each 

prospective SAU is presented. Key information that provides the basis for calculating the capacity of each

SAU for buoyant and residual CO2 storage (as described in Burruss and others, 2009; Brennan and others, 

2010; Blondes and others, 2013), as well as information that relates to the reservoir characteristics for 

each unit, is also summarized. Such key input parameters include depth from surface; area; gross 

thickness; net-porous-interval thickness, or the portion of the SAU gross thickness that contains porous 

rock identified as being sufficient for CO2 storage; porosity of the net-porous-interval; and range of 

permeability for the entire SAU. Because the U.S. Environmental Protection Agency (EPA; 2009, 2013) 

stipulates that aquifers used for CO2 sequestration must contain groundwater with a TDS concentration 

greater than 10,000 mg/L, regional trends in groundwater quality for an assessed area are characterized, 

and the area fraction of the SAU that is available for CO2 storage is estimated. All parameters were 

estimated using a combination of proprietary databases (such as IHS Energy Group, 2010, 2011 and 

Nehring Associates, Inc., 2010); public and non-proprietary databases; and published literature, including 

isopachs, structure maps, and cross-sections.

Finally, in order to differentiate between the pore volume contained within buoyant traps and that 

contained within residual traps for the various SAUs (see Brennan and others, 2010; Blondes and others, 

2013), the pore volume enclosed within buoyant traps, which are analogous to stratigraphic and (or) 

structural hydrocarbon traps, is defined. For each SAU, (a) minimum and (b) most likely pore volumes 

enclosed within buoyant traps were constrained on the basis of (1) the sum of the cumulative oil and gas 

production and the known hydrocarbon reserve volume and (2) the minimum buoyant pore volume plus 
4

the estimated volume of undiscovered resources (see Brennan and others, 2010; Blondes and others, 

2013). Because this method was applied to all SAUs, it is not discussed on a case-by-case basis. An upper 

bound for enclosed pore volume was also determined for each unit, and methods for the various SAUs are 

discussed on a case-by-case basis. The information derived from the data sources and methods described 

in this report were used in accordance with the USGS Carbon Sequestration Assessment Methodology 

(Brennan and others, 2010; Blondes and others, 2013) to calculate the available storage space for CO2

within each SAU.

Stratigraphic columns are provided that display the stratigraphy within the U.S. Gulf Coast study 

area, as well as that within each SAU that was identified for these rocks (figs. 2A, 2B, 2C, 2D, and 2E).

These stratigraphic columns indicate stratigraphy variation from east to west across the study area; they 

do not display stratigraphic variation from updip to downdip. Additionally, the authors recognize that 

there is some contradiction in chronostratigraphy for Jurassic and Cretaceous units within the study area 

(see Swain, 1944; Goldhammer and Johnson, 2001; Mancini and Puckett, 2005; Mancini and others, 

2008b; Rosen and Rosen, 2008). At this time, and until further investigation can be conducted, data and 

age of rocks presented by Goldhammer and Johnson (2001), Mancini and Puckett (2005), and Mancini 

and others (2008b) are adapted for this report.
5

Figure 1. Geologic map of the U.S. Gulf Coast study area within the southern U.S. Major structural features adapted from Ewing and Lopez (1991) and 

Galloway (2011). In the inset on the lower left, area in red is the U.S. Gulf Coast study area.
6 

Figure 2A. Main stratigraphic column for the U.S. Gulf Coast study area. Wavy lines indicate unconformable 

contacts, and gray areas represent unconformities. Adapted from Salvador and Quezada-Muñeton (1991), Dubiel 

and others (2007a), Warwick and others (2007), and Mancini and others (2008b). Ls = Limestone; Fm = 

Formation; Mbr = Member. 

Werner Fm
7 

Figure 2B. Stratigraphic column displaying the east-west distribution of the Upper Jurassic and Cretaceous 

geologic units within the U.S. Gulf Coast study area. Storage assessment units consist of a reservoir (red) and

regional seal (blue). Wavy lines indicate unconformable contacts, and gray areas represent unconformities. 

Adapted from Nehring (1991), Salvador and Quezada-Muñeton (1991), Goldhammer and Johnson (2001), 

Witrock and others (2003), Sweezey and Sullivan (2004), Mancini and Puckett (2005), Warwick and others 

(2007), Mancini and others (2008b), Valentine and Dennen (2012), and Walker and others (2012). 
8

Figure 2C. Stratigraphic column displaying the east-west distribution of the Upper Cretaceous and lower 

Tertiary rocks within the U.S. Gulf Coast study area. Storage assessment units consist of a reservoir (red) and 

regional seal (blue). Wavy lines indicate unconformable contacts. Adapted from Salvador and Quezada-Muñeton 

(1991), Warwick and others (2007), and Mancini and others (2008b). Fm = Formation.
9 

Figure 2D. Stratigraphic column displaying the east-west distribution of the Tertiary rocks within the U.S. Gulf Coast study area—Part 1. Storage 

assessment units consist of a reservoir (red) and regional seal (blue). Wavy lines indicate unconformable contacts. Adapted from Salvador and

Quezada-Muñeton (1991), Galloway and others (1994), Lawless and others (1997), Warwick and others (1997, 2007), Witrock and others (2003), 

Dubiel and others (2007a), and Valentine and Dennen (2012), Walker and others (2012). Fm = Formation. 
10 

Figure 2E. Stratigraphic column displaying the east-west distribution of the Tertiary rocks within the U.S. Gulf 

Coast study area—Part 2. Storage assessment units consist of a reservoir (red) and regional seal (blue). Wavy 

lines indicate unconformable contacts. Adapted from Dubiel and others (2007a), Warwick and others (2007), and

Mancini and others (2008b).
11

Norphlet Formation SAU C50490101 and Norphlet Formation Deep SAU 

C50490102

By Marc L. Buursink

The Norphlet Formation SAUs consist of those portions of the preserved Upper Jurassic (lower

Oxfordian) siliciclastic lithology deemed suitable as reservoir rock for CO2 sequestration that occurs 

beneath a regionally extensive seal in the U.S. Gulf Coast study area (figs. 1, 2A, and 2B). The Jurassic 

section in the northern basin of the U.S. Gulf Coast consists of siliciclastic, carbonate, and evaporite 

deposits, which accumulated after the break-up of Pangaea in continental to deeper marine environments, 

where the bathymetry was modified by salt tectonics or basement features (Mancini and others, 1990; 

Rhodes and Maxwell, 1993). The Norphlet Formation comprises sandstone, conglomeratic sandstone, and 

interbedded shale and siltstone deposited in eolian dune, alluvial fan, and fluvial and nearshore marine 

system environments (Salvador, 1991a; Mancini, 2010). Regionally, the lime mudstone of the lower 

portion of the Smackover Formation overlies the Norphlet Formation (Nehring, 1991; Salvador, 1991b) 

and functions as the sealing lithology (fig. 2B). The gray to black, carbonate mudstone and argillaceous 

limestone of the lower Smackover Formation were deposited in low-energy environments (Schenk and 

Viger, 1995a,b; Dubiel and others, 2011). Hydrocarbon exploration and exploitation in the Smackover 

Formation shales (Mancini and others, 2008a) may potentially compromise the seal for the Norphlet 

Formation CO2 storage reservoir.

The Norphlet Formation SAU boundaries are constrained by the presence and depth below the 

surface of the top of the storage formation and by the presence and thickness of the regional seal.

Formation picks for the Norphlet Formation, as reported in a commercial database (IHS Energy Group, 

2011), helped define the top of each SAU. The SAU boundary interpretations were supported by (a) the 

Gulf of Mexico Basin geologic maps and cross sections in the Geological Society of America’s Decade of 

North American Geology volume by Salvador (1991a,b), (b) the chapter and maps on the depositional 

evolution of the Gulf of Mexico by Galloway (2008), (c) the maps for reservoirs and petroleum systems 

of the Gulf Coast by Pitman (2011), and (d) formation tops (IHS Energy Group, 2011) differencing to 

obtain the regional seal thickness. Consequently, Norphlet Formation SAU C50490101 ranges between 

3,000 and 13,000 ft in depth and has about a 29 million-acre most-likely area, whereas the Norphlet 

Formation Deep SAU C50490102 ranges between 13,000 and 22,000 ft and has about a 62 million-acre 

most-likely area (fig. 3). The larger Norphlet Formation Deep SAU extends from the U.S. and Mexico 

border toward the northeast and adjoins the Norphlet Formation SAU out to the Florida panhandle.

The thickness and facies distribution of the Norphlet Formation was affected by the paleotopography of the U.S. Gulf Coast (Mancini and others, 1990; Rhodes and Maxwell, 1993). Regionally, 

the gross thicknesses range up to about 100 ft (Salvador, 1991b) onshore, whereas farther offshore, the 

thicknesses range from 600 to 800 ft (Mink and others, 1990). Analysis of the stratigraphy, net-to-gross 

ratio, and net-porous intervals of the Norphlet Formation within the SAUs were conducted using 

descriptions by Marzano (1988) and Bolin and others (1989); using cross sections by Hughes (1968) and 

Tew and others (1991); and were supplemented with sand and isopach maps by Schenk and Schmoker 

(1993) and Salvador (1987, 1991b), respectively. The Norphlet Formation SAU C50490101 average gross 

thickness ranges from 150 to 1,000 ft, with an average net-porous thickness between 100 and 300 ft. The

Norphlet Formation Deep SAU C50490102 gross thickness ranges from 80 to 500 ft, with a net-porous 

thickness between 50 and 150 ft.

The Norphlet Formation is a productive oil and gas interval in the U.S. Gulf Coast, and reservoirquality data are reported in multiple publications and databases. The first oil and gas discovery in the 
12

Norphlet Formation was made in 1967, and since then 15 fields in mostly structural traps have produced 

12 MMBO and 138 billion cubic feet of gas (Bearden and others, 2000). Despite relatively deep

reservoirs, Norphlet Formation porosity is described as excellent (Bolin and others, 1989; Dixon and 

others, 1989). Published porosity and permeability values (Badon, 1975; Mancini, 2010) were compared 

to sandstone analogs (Nelson and Kibler, 2003; Ehrenberg and others, 2009), and average field values 

obtained from Nehring Associates, Inc. (2010) for the U.S. Gulf Coast study area were used for additional 

comparison. Based upon a review of these published results, the Norphlet Formation SAU C50490101 

was assigned an average porosity range from 10 to 18 percent and a permeability range from 10 to 1,000 

millidarcies (mD). The Norphlet Formation Deep SAU C50490102 was assigned an average porosity 

range from 5 to 15 percent and a permeability range from 1 to 900 mD.

Water-quality data obtained from a published database (Breit, 2002) indicates that saline 

formation waters (TDS >10,000 mg/L) are predominant within the Norphlet Formation SAUs; this is 

expected considering the storage formation overlies the Middle and Upper Jurassic Louann Salt 

(Galloway, 2008; Mancini, 2010). Only relatively small areas exist within the SAUs that contain 

groundwater with TDS values below the EPA underground sources of drinking water limit of 10,000 

mg/L (EPA, 2009, 2010). Consequently, the storage formation areas with groundwater having TDS values 

below the 10,000 mg/L total TDS limit were delineated for each SAU and made up about 5 percent each 

of the estimated Norphlet Formation SAU and Norphlet Formation Deep SAU areas.

To create a probabilistic maximum for buoyant-trapping volume within each of the SAUs, first the 

Nehring Associates, Inc. (2010) field locations were plotted and the average field size was computed. The 

field locations and size were then extrapolated across the remaining SAU areas and summed to generate 

the probabilistic maximum. This estimate was made with the assumption that structural traps are 

dominant in the areas of the SAUs (Bearden and others, 2000).
13

Figure 3. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Norphlet Formation and Norphlet Formation Deep SAUs

in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have 

penetrated the reservoir-formation top.
14

Smackover Formation SAU C50490103 and Smackover Formation Deep SAU 

C50490104

By Marc L. Buursink

The Smackover Formation SAUs consist of those portions of the preserved Upper Jurassic (upper 

Oxfordian) carbonate lithology deemed suitable as reservoir rock for CO2 sequestration that occurs 

beneath a regionally extensive Buckner Member of Haynesville Formation seal in the U.S. Gulf Coast 

study area (figs. 1, 2A, and 2B). The Jurassic section in the northern basin of the U.S. Gulf Coast consists 

of siliciclastic, carbonate, and evaporite deposits, which accumulated after the breakup of Pangaea in 

continental to deeper marine environments, where the bathymetry was modified by salt tectonics or 

basement features (Mancini and others, 1990; Rhodes and Maxwell, 1993). The Smackover Formation 

consists of coral-microbial and microbial buildups developed during the maximum marine transgression 

in the late Oxfordian, and higher energy nearshore and shoal deposits accumulated with a slowing of sea 

level rise (Mancini, 2010). The upper portion of the Smackover Formation consists of mostly grainsupported carbonates, including grainstones, packstones, and boundstones deposited in high-energy, 

shallow-water environments (Salvador, 1991b). Regionally, the anhydrite of the Buckner Member of 

Haynesville Formation and the undifferentiated mudstones of the lower portion of the Haynesville 

Formation overlie the Smackover Formation storage reservoir (Schenk and Viger, 1995b; Moore, 1997; 

Cicero and others, 2010) and function as the sealing lithology (fig. 2B). The Buckner Member 

accumulated on shoal-restricted, shallow, inner platforms (Galloway, 2008), and the Haynesville 

Formation mudstone was deposited as contemporaneous retrogradational and progradational facies across 

a restricted basin (Cicero and others, 2010). Hydrocarbon exploration and exploitation in the Haynesville 

Formation shales (U.S. Energy Information Administration, 2011) may potentially compromise the seal 

for the Smackover Formation CO2 storage reservoir.

The Smackover Formation SAU boundaries are constrained by (a) the presence and depth below 

the surface of this storage-formation top, (b) by the presence and thickness of a regional seal, and (c) by 

the extent of the State waters. Formation picks for the Smackover Formation, as reported in a commercial 

database (IHS Energy Group, 2011), helped define the top of each SAU. These interpretations were

supported by (a) the Gulf of Mexico Basin geologic maps and cross sections in the Geological Society of 

America’s Decade of North American Geology volume by Salvador (1991a,b), (b) the chapter and maps 

on the depositional evolution of the Gulf of Mexico by Galloway (2008), (c) the maps for reservoirs and 

petroleum systems of the Gulf Coast by Pitman (2011), and (d) formation tops (IHS Energy Group, 2011) 

differencing to obtain the regional seal thickness. Consequently, Smackover Formation SAU C50490103 

ranges from 3,000 to 13,000 ft in depth and has about a 31 million-acre most-likely area, whereas the 

Smackover Formation Deep SAU C50490104 ranges from 13,000 to 24,000 ft in depth and has about a 44 

million-acre most-likely area (fig. 4). The Smackover Formation SAU and the Smackover Formation 

Deep SAU adjoin and extend from east Texas to the Florida panhandle and the edge of the State waters.

The Smackover Formation thickness is deformed by multiple extensional faults and grabens 

related to salt movement (Mancini and others, 1990). Regionally, the gross thickness of the Smackover 

Formation ranges from a few hundred feet (onshore and coastal areas of northeastern Gulf of Mexico) to 

over a thousand feet (south-southwest of coastal areas) (Mancini and others, 1990). Analysis of the 

stratigraphy, net-to-gross ratio, and net-porous intervals of the Smackover Formation within the SAUs

were mainly conducted using data provided by Nehring (1991), Nehring Associates, Inc. (2010), and 

Fishman and others (2008), and were supplemented by isopach maps from Mancini and Benson (1980) 
15

and Cagle and Khan (1983). The Smackover Formation SAU C50490103 average gross thickness ranges 

from 100 to 500 ft, with an average net-porous thickness between 50 and 200 ft. The Smackover 

Formation Deep SAU C50490104 average gross thickness ranges from 80 to 400 ft, with an average netporous thickness between 40 and 100 ft.

The Smackover Formation is a productive oil and gas interval in the U.S. Gulf Coast, and 

reservoir-quality data are reported in multiple publications and databases. The first oil and gas discovery 

in the Smackover Formation was made in 1963, and since then 82 fields in structural and combination 

traps have produced 258 MMBO and 1 trillion cubic feet of gas (Bearden and others, 2000). Diagenesis 

has affected reservoir porosity and permeability in the Smackover Formation (Moore, 1997; Fowler and 

Benson, 2000). More porous intervals in the Smackover Formation are found in fields that rim the 

northern margin of the Gulf of Mexico Basin (Nehring, 1991). Published porosity and permeability values 

(Fishman and others, 2008; Mancini, 2010) were compared to carbonate analogs (Murray, 1960; 

Ehrenberg and others, 2009), and average field values obtained from Nehring Associates, Inc. (2010) for 

the U.S. Gulf Coast study area were used for additional comparison. Based upon a review of these 

published results, the Smackover Formation SAU C50490103 was assigned an average porosity range 

from 10 to 20 percent and a permeability range from 0.1 to 1,000 mD. The Smackover Formation Deep 

SAU C50490104 was assigned an average porosity range from 8 to 15 percent and a permeability range 

from 0.01 to 500 mD.

Water-quality data obtained from a published database (Breit, 2002) indicates that saline 

formation waters (TDS >10,000 mg/L) are predominant within the Smackover Formation SAUs, and this

is expected considering the storage formation overlies the Middle and Upper Jurassic Louann Salt and 

underlies evaporites of the Buckner Member of the Haynesville Formation (Galloway, 2008; Mancini, 

2010). Only relatively small areas exist within the SAUs that contain groundwater with TDS values below 

the EPA underground sources of drinking water limit of 10,000 mg/L (EPA, 2009, 2010). Consequently, 

the storage formation areas with groundwater having TDS values below the 10,000 mg/L total TDS limit 

were delineated for each SAU and made up about 5 percent each of the estimated Smackover Formation 

SAU and Smackover Formation Deep SAU areas.

To create a probabilistic maximum for buoyant-trapping volume within each of the SAUs, first the 

Nehring Associates, Inc. (2010) field locations were plotted and the average field size was computed. The 

field locations and size were then extrapolated across the remaining SAU areas and summed to generate 

the probabilistic maximum. This estimate was made with the assumption that structural traps are 

dominant in the areas of the SAUs (Bearden and others, 2000).
16

Figure 4. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Smackover Formation and Smackover Formation Deep 

SAUs in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that 

have penetrated the reservoir-formation top.
17

Haynesville Formation SAU C50490105 and Haynesville Formation Deep SAU 

C50490106

By Tina L. Roberts-Ashby

The Upper Jurassic Haynesville Formation is a carbonate and siliclastic unit within the U.S. Gulf 

Coast (Forgotson and Forgotson, 1976) that forms a potential CO2 storage reservoir that mainly extends 

across eastern Texas and into north-central Louisiana (figs. 2A, 2B, and 5). The carbonates within the 

Haynesville Formation have also been referred to as the Cotton Valley Lime/Limestone, Gilmer 

Limestone, or Buckner Limestone (Forgotson and Forgotson, 1976; Ahr, 1981; Nehring, 1991), and were 

generally deposited on a mature ramp in a shallow-water, marine-shoal environment, possibly during sealevel regression, and commonly over salt-supported structures (Ahr, 1981; Byram, 1988; Nehring, 1991).

The Haynesville Formation carbonates have undergone little dolomitization (Ahr, 1981) and have varying 

lithology that includes dense, micritic limestones; oolitic and pseudo-oolitic limestones; argillaceous 

limestones; and pelletal grainstones and packstones (Forgotson and Forgotson, 1976; Ahr, 1981). The 

carbonate rocks within the Haynesville Formation grade into siliciclastics to the west, north, and 

northeast, and predominate in northeastern Louisiana, southeastern Arkansas, and central Mississippi 

(Forgotson and Forgotson, 1976; Salvador, 1991b). The Haynesville Formation siliciclastics include 

coarse sandstones and conglomerates, organic-rich shales, and calcareous shales that are terrigenous, nonmarine, as well as near-shore and marginal-marine sediments that underwent some degree of marine 

reworking (Maher and others, 1968; Forgotson and Forgotson, 1976; Nehring, 1991; Salvador, 1991b; 

Mancini, 2010). Within the region of the CO2 storage reservoir, the producing sandstones of the 

Haynesville Formation are concentrated in northern Louisiana. Depending upon location within the U.S. 

Gulf Coast, the Haynesville Formation carbonate and siliciclastic reservoirs are either underlain by the 

evaporites of the Buckner Member of the Haynesville Formation, or the evaporites of the Smackover 

Formation, and are overlain by the Upper Jurassic and Lower Cretaceous Bossier Formation (or Bossier 

Shale) of the Cotton Valley Group (fig. 2B; Maher and others, 1968; Forgotson and Forgotson, 1976). In 

the area of the potential CO2 storage reservoir, the Bossier Formation forms the overlying seal and is 

predominantly a thick shale unit (Swain, 1944). The thickness of the Bossier Formation is variable 

throughout the U.S. Gulf Coast, especially in northern Louisiana, but can be as thick as 2,000 ft (Swain, 

1944). 

Two potential CO2 storage reservoir units are identified in the Haynesville Formation of the U.S. 

Gulf Coast: (1) between 3,000 and 13,000 ft subsurface depth—Haynesville Formation C50490105, and 

(2) below 13,000 ft subsurface depth—Haynesville Formation Deep C50490106 (fig. 5). The Haynesville 

Formation SAU C50490105 encompasses an area of about 14,166,000 acres (+10 percent), and the 

Haynesville Formation Deep SAU C50490106 is about 8,771,000 acres (+ 10 percent). 

The boundaries of the Haynesville Formation SAUs are defined by the 3,000-ft and 13,000-ft 

reservoir-top depths taken from 3,054 well penetrations (IHS Energy Group, 2010), faults associated with 

the Mexia-Talco fault zone, and the extent of the shales within the Bossier Formation seal (IHS Energy 

Group, 2010). The rocks within the Haynesville Formation SAUs deepen to the south, toward the Gulf of 

Mexico and Lower Cretaceous shelf margin, and on average are 300 to 750 ft thick (SAU C50490105) 

and 300 to 800 ft thick (SAU C50490106), with a most-likely thickness of 550 ft (SAU C50490105) and 

600 ft (SAU C50490106), as determined by using the differences in depth-to-tops in 506 well 

penetrations located throughout the SAUs (IHS Energy Group, 2010). 
18

Maximum porosity is highest within the sandstones and conglomerates of the Haynesville 

Formation (as much as 20 percent; Ahr, 1981); however, the majority of the Haynesville Formation SAUs 

are composed of carbonate rocks. Average porosity in the porous intervals of the Haynesville Formation 

decreases with depth from 7 to 14 percent in the Haynesville Formation SAU C50490105 to 3 to 11 

percent in the Haynesville Formation Deep SAU C50490106 (Nehring Associates, Inc., 2010), which is 

primarily attributed to increased mudstone and micritic limestone content and cementation with depth in 

the carbonate rocks of the Haynesville Formation (Ahr, 1981). Net-porous-interval thickness was 

estimated by multiplying the total storage formation thickness by an average net porous thickness-to-gross 

thickness ratio, which was interpreted from geophysical logs. A net-to-gross ratio of 0.35 was used for the 

Haynesville Formation SAU C50490105 resulting in an average net-porous-interval thickness that ranges 

from 100 to 260 ft, with a most-likely value of 190 ft. A net-to-gross ratio of 0.30 was used for the 

Haynesville Formation Deep SAU C50490106 resulting in an average net-porous-interval thickness of 90

to 240 ft, with a most-likely value of 180 ft. Porosity in the carbonate rocks of the Haynesville Formation 

is typically intragranular, which formed by leaching and mineralogic stabilization of grains (Ahr, 1981; 

Nehring, 1991), and any intergranular pore space has, for the most part, been filled by carbonate cements, 

thereby decreasing porosity (Ahr, 1981; Nehring, 1991). Because most of the porosity in the carbonate 

rocks of the Haynesville Formation SAUs is intragranular, average permeability is quite low and the 

formation requires fracturing or acidization for optimal commercial petroleum production (Nehring, 

1991). The permeability of the sandstones within the Haynesville Formation SAUs is generally good, 

however, it decreases with depth (Nehring, 1991; Ryder, 1996; Cicero and others, 2010). Average 

permeability in the Haynesville Formation decreases with depth from 0.01 to 500 mD, with a most-likely

value of 0.5 mD in the Haynesville Formation SAU C50490105 to 0.005 to 200 mD, with a most-likely

value of 0.3 mD in the Haynesville Formation Deep SAU C50490106 (Nehring Associates, Inc., 2010). 

No major or minor potable-water aquifers in Texas occur within the Haynesville Formation 

(Ryder, 1996). Water sampled from two wells within the areas of the Haynesville Formation SAUs 

indicates saline formation waters, with TDS values well above 10,000 mg/L (Breit, 2002). Additionally, 

there are over 100 underground injection control wells within the Louisiana portion of the Haynesville 

Formation SAUs that are injecting “waste” (some of which is from oil and gas production) into 

subsurface depths of 3,000 ft to 11,000+ ft (Louisiana Department of Natural Resources, 2011), which 

indicates nonpotable, saline groundwater conditions. Because the Haynesville Formation SAU 

C50490105 does not appear to contain potable, freshwater (TDS <10,000 mg/L), 100 percent of its area is 

considered suitable for subsurface storage of CO2. Furthermore, because salinity within the region 

increases with depth (Ryder, 1996), 100 percent of the Haynesville Formation Deep SAU C50490106 is 

expected to be entirely saline (TDS >10,000 mg/L) and suitable for geologic CO2 storage, as well. 

In order to calculate the maximum buoyant pore volume within structural and stratigraphic 

closures for each Haynesville Formation SAU, the known closure areas from the highly productive 

regions located throughout the Haynesville Formation SAUs were extrapolated and combined with upper 

bounds on regional reservoir thickness and porosity. The known closure areas were calculated by 

summing petroleum reservoir areas for each Haynesville Formation SAU (Nehring Associates, Inc., 

2010). An assumption underlying this calculation is that there is potential for additional uncharged or 

undiscovered structural and stratigraphic closures outside of regions of historical hydrocarbon production.
19

Figure 5. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Haynesville Formation and Haynesville Formation Deep 

SAUs in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that 

have penetrated the reservoir formation top.
20

Sligo and Hosston Formations and Cotton Valley Group SAU C50490107 and 

Sligo and Hosston Formations and Cotton Valley Group Deep SAU C50490108

By Tina L. Roberts-Ashby

The Lower Cretaceous Sligo Formation and Hosston Formation of the Trinity Group, together 

with the Upper Jurassic and Lower Cretaceous Cotton Valley Group, make up a large storage reservoir 

identified as potentially suitable for CO2 sequestration that extends across the entire U.S. Gulf Coast (figs. 

2A, 2B, and 6). The Cotton Valley Group is generally composed of three formations (the Bossier 

Formation, Schuler Formation, and Knowles Limestone), although in some areas of the region, one unit 

may be missing or thin, and localized units may be included. The Bossier Formation is a thick shale unit 

that serves as the regional seal for the underlying Haynesville Formation SAUs and is therefore not 

included in the Sligo and Hosston Formations and Cotton Valley Group SAUs. The Schuler Formation is 

a progradational, fluvial-deltaic sequence composed of sandstone, siltstone, and some shales (Maher and 

others, 1968; Forgotson and Forgotson, 1976; Goldhammer and Johnson, 2001; Dyman and Condon, 

2006; Mancini, 2010), and in some locations of the Gulf Coast is divided into the Shongaloo and 

Dorcheat Members (Goldhammer and Johnson, 2001; Mancini, 2010). The Shongaloo Member is a 

marginal-marine and coastal sandstone deposit, whereas the Dorcheat Member is composed of sandy 

shales, sandstones, and conglomerates associated with a maximum flooding surface (Mancini, 2010). The 

Knowles Limestone overlies the Schuler Formation across most of the U.S. Gulf Coast and is a carbonate 

unit, generally ~300 to 400 ft thick, that was deposited during a major sea level transgression that 

subsequently resulted in the cessation of fluvial-deltaic sedimentation in the Gulf of Mexico Basin 

(Herrmann and others, 1999; Ewing, 2001; Dyman and Condon, 2006). In some areas of the U.S. Gulf 

Coast, the mostly limestone unit contains relatively porous, storage-reservoir-quality rocks, especially in 

dolomitized regions, whereas other areas the limestones are cemented and tight, contain very little 

porosity and permeability, and contribute to the sealing of underlying sands (Coleman and Coleman, 

1981; Cregg and Ahr, 1983; Mahbubullah, 1989). Predominantly, the Knowles Limestone is composed of 

a tight, argillaceous and calcite-cemented limestone with gray shales and is of low porosity and 

permeability (Coleman and Coleman, 1981; Cregg and Ahr, 1983; Herrmann and others, 1999). Seaward 

of the Knowles-Winn reef trend, few wells have penetrated the Knowles Limestone, and the reservoir 

quality of the unit is poorly characterized. Seaward of the Knowles-Winn reef trend, the Cotton Valley 

Group also contains a second carbonate unit with relatively good porosity but low permeability, known as 

the Winn Limestone, as well as a massive sand complex, known as the Calvin Sandstone (Coleman and 

Coleman, 1981; J. Coleman, USGS, written commun., 2011). Because the Knowles Limestone, Calvin 

Sandstone, and Winn Limestone do not occur or are of poor reservoir quality landward of the KnowlesWinn reef trend, they have minimal contribution to the total storage-reservoir interval within the Sligo and

Hosston Formations and Cotton Valley Group SAUs within that region. However, seaward of the 

Knowles-Winn reef trend and up to the southern boundary of the SAUs, or the Lower Cretaceous reef 

trend (see figs. 1 and 6), the Knowles and Winn Limestones and Calvin Sandstone partially contribute to 

the porous intervals within the SAUs. 

A pro-delta and fluvial-deltaic deposit, known as the Hosston Formation in Louisiana and the 

Travis Peak Formation in Texas and southern Arkansas, overlies the Cotton Valley Group throughout the 

U.S. Gulf Coast, with the exception of updip portions of the Gulf of Mexico Basin where the Knowles 

Limestone pinches out and the Hosston Formation directly overlies the Schuler Formation (Dyman and 

Condon, 2006). The Hosston/Travis Peak Formation is a thick wedge of terrigenous sedimentary rocks
21

that marks the second major influx of siliciclastics to the northern Gulf of Mexico Basin (Dyman and 

Condon, 2006). The Sligo Formation conformably overlies the Hosston Formation and is predominantly

composed of siliciclastics in Mississippi, Alabama, and Florida, whereas in Louisiana and Texas, the 

formation is predominantly composed of shelf-edge limestones (Rainwater, 1971; Ewing, 2001; Dyman 

and Condon, 2006). The shelf was eventually drowned by the black shales of the Lower Cretaceous 

Hammett Shale and Pine Island Shale Members of the Pearsall Formation (Trinity Group; Ewing, 2001), 

which can be hundreds of feet thick and forms the regional seal for the storage reservoir.

Two potential CO2 storage reservoir units are identified in the Sligo and Hosston Formations and 

Cotton Valley Group within the U.S. Gulf Coast: (1) between 3,000 and 13,000 ft subsurface depth—

Sligo and Hosston Formations and Cotton Valley Group C50490107, and (2) below 13,000 ft subsurface 

depth—Sligo and Hosston Formations and Cotton Valley Group Deep C50490108 (fig. 6). The Sligo and

Hosston Formations and Cotton Valley Group SAU C50490107 encompasses an area of about 51,984,000 

acres (+10 percent), and the Sligo and Hosston Formations and Cotton Valley Group Deep SAU 

C50490108 is about 20,937,000 acres (+10 percent). 

The boundaries of the Sligo and Hosston Formations and Cotton Valley Group SAUs are defined 

by the 3,000-ft and 13,000-ft reservoir-top depths taken from 27,087 well penetrations (IHS Energy 

Group, 2010); the U.S.-Mexico international border; the U.S. Gulf Coast State-water lines; the MexiaTalco, Gilbertown, and Pickens fault zones; areas where Lower Cretaceous rocks outcrop; the Lower 

Cretaceous reef trend/shelf margin, which marks the southern extent of a thick, continuous Hammett 

Shale and Pine Island Shale Members seal along the southern SAU boundary, in addition to the extent of 

which the Sligo and Hosston Formations and Cotton Valley Group have been explored and characterized 

to date (Dyman and Condon, 2006); and the extent of the continuous Hammett Shale and Pine Island 

Shale Members that is at least 50 ft thick, specifically along the northern boundary. The rocks within the 

Sligo and Hosston Formations and Cotton Valley Group SAUs deepen and thicken to the south and 

southeast toward the Gulf of Mexico and Lower Cretaceous shelf margin (fig. 6) and on average are 3,150

to 4,200 ft thick (SAU C50490107) and 4,300 to 6,000 ft thick (SAU C50490108), with a most-likely

thickness of 3,750 ft (SAU C50490107) and 5,000 ft (SAU C50490108), as determined by using the 

differences in depths-to-tops in 4,861 well penetrations located throughout the SAUs (IHS Energy Group, 

2010). 

Average porosity in the porous intervals of the storage reservoir decreases with depth from 10 to 

20 percent in the Sligo and Hosston Formations and Cotton Valley Group SAU C50490107 to 9 to 16 

percent in the Sligo and Hosston Formations and Cotton Valley Group Deep SAU C50490108 (Nehring 

Associates, Inc., 2010). Net-porous-interval thickness was estimated by multiplying the total storage 

formation thickness by an average net-porous-thickness to gross-thickness ratio of 0.63, which was 

interpreted from geophysical logs. This resulted in an average net-porous-interval thickness that ranges 

from 2,000 to 2,650 ft, with a most-likely value of 2,400 ft for the Sligo and Hosston Formations and 

Cotton Valley Group SAU C50490107, and an average net-porous-interval thickness that ranges from 850

to 1,200 ft, with a most-likely value of 1,000 ft for the Sligo and Hosston Formations and Cotton Valley 

Group Deep SAU C50490108. Average permeability in the storage reservoirs decreases with depth from 

0.1 to 3,300 mD, with a most-likely value of 35 mD in the Sligo and Hosston Formations and Cotton 

Valley Group SAU C50490107, to 0.05 to 200 mD, with a most-likely value of 8 mD in the Sligo and

Hosston Formations and Cotton Valley Group Deep SAU C50490108 (Nehring Associates, Inc., 2010). 

Two aquifers occur within the region of the Sligo and Hosston Formations and Cotton Valley 

Group SAUs, both of which contain saline water (TDS >10,000 mg/L) as well as fresh, potable water 

(TDS <10,000 mg/L), depending upon depth and location within the U.S. Gulf Coast: the Lower Trinity 

aquifer and the Southeastern Coastal Plain aquifer. According to cross-sections and regional maps 

(Renken, 1996; Ryder, 1996; George and others, 2011), only a small portion of the Sligo and Hosston 

Formations and Cotton Valley Group SAU C50490107, along its eastern boundary, potentially lies within 
22

the potable-water region of the Lower Trinity aquifer, and no portion of the Sligo and Hosston Formations 

and Cotton Valley Group Deep SAU C50490108 appears to be located within the aquifer’s potable-water 

extent. No portion of either of the Sligo and Hosston Formations and Cotton Valley Group SAUs appears 

to be located within the freshwater region of the Southeastern Coastal Plain aquifer, according to regional 

aquifer contour maps (Miller, 1990). A nationwide database of TDS concentrations shows formation 

waters within the SAUs are predominantly saline (TDS >10,000 mg/L); however, there are some small 

regions that appear to contain freshwater (TDS <10,000 mg/L) within the SAU interval (Breit, 2002). For 

the Sligo and Hosston Formations and Cotton Valley Group SAU C50490107, because some small 

portions of the region contain accumulations of potentially potable water, 90 percent (at the mode, with a 

minimum of 75 percent and a maximum of 95 percent) of the SAU area is considered potentially suitable 

for geosequestration of CO2. For the Sligo and Hosston Formations and Cotton Valley Group Deep SAU 

C50490108, significantly smaller portions of the region appear to contain accumulations of potentially 

potable water; therefore, most of the SAU area (most likely 95 percent, with a minimum of 95 percent and 

a maximum of 100 percent) is considered potentially suitable for geosequestration of CO2.

In order to calculate the maximum buoyant pore volume within structural and stratigraphic 

closures for each Sligo and Hosston Formations and Cotton Valley Group SAU, the known closure areas 

from the highly productive regions located throughout the SAUs were extrapolated and combined with 

upper bounds on regional reservoir thickness and porosity. The known closure areas were calculated by 

summing petroleum reservoir areas for each Sligo and Hosston Formations and Cotton Valley Group 

SAU (Nehring Associates, Inc., 2010). An assumption underlying this calculation is that there is potential 

for additional uncharged or undiscovered structural and stratigraphic closures outside of regions of 

historical hydrocarbon production.
23

Figure 6. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Sligo and Hosston Formations and Cotton Valley Group

and Sligo and Hosston Formations and Cotton Valley Group Deep SAUs in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells 

derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation top.
24

Knowles and Winn Limestones and Calvin Sandstone SAU C50490109

By Tina L. Roberts-Ashby

Seaward of the Knowles-Winn reef trend, the Lower Cretaceous interval of the upper portion of 

the Cotton Valley Group is composed of, from oldest to youngest, the Knowles Limestone, Calvin 

Sandstone, and Winn Limestone (figs. 2A and 2B). These geologic units are included in the Sligo and 

Hosston Formations and Cotton Valley Group SAUs of the U.S. Gulf Coast, with a southern extent up to 

the Lower Cretaceous reef trend/shelf margin, where there is a known, continuous shale seal (Hammett 

Shale and Pine Island Shale Members) within the Pearsall Formation. However, from the Lower 

Cretaceous reef trend/shelf margin seaward to the State-water lines within the U.S. Gulf Coast, this 

portion of the Cotton Valley Group is identified as the Knowles and Winn Limestones and Calvin 

Sandstone SAU C50490109 (fig. 7). The units collectively comprise a storage reservoir that is potentially 

suitable for subsurface storage of CO2 in the U.S. Gulf Coast, based upon knowledge of the rocks 

landward of the reef trend, but that has no well-drilling or exploration, thereby hindering the ability to 

accurately characterize the reservoir rocks and presence of a regional seal. 

The Knowles and Winn Limestones and Calvin Sandstone SAU C50490109 is overlain by an 

unnamed shale unit within the lowermost Hosston Formation and uppermost Cotton Valley Group that 

has been eroded and is not present north of the Knowles-Winn reef trend, where the Sligo and Hosston 

Formations and Cotton Valley Group SAUs are located (Coleman and Coleman, 1981; Dyman and 

Condon, 2006; J. Coleman, USGS, written commun., 2011). This shale could potentially serve as a seal 

for the Knowles and Winn Limestones and Calvin Sandstone SAU C50490109; however, due to lack of 

drilling and exploration activity in the region of the SAU, the thickness and extent of this potential shale 

seal cannot be characterized. The Knowles and Winn Limestones and Calvin Sandstone SAU C50490109 

encompasses an area of approximately 65,023,000 acres that could potentially serve as a CO2

geosequestration reservoir; however, because the CO2 storage reservoir assessment methodology 

(Brennan and others, 2010) requires a continuously thick, well-documented, and mappable regional seal, 

this SAU was not quantitatively assessed.
25

Figure 7. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Knowles and Winn Limestones and Calvin Sandstone

SAU in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that 

have penetrated the reservoir formation top.
26

Rodessa Formation and James Limestone SAU C50490110 and Rodessa 

Formation and James Limestone Deep SAU C50490111

By Peter D. Warwick

The northern part of the U.S. Gulf Coast is located in the southeastern part of the United States 

(fig. 1). To define the region margin for this assessment, the Upper Jurassic-Cretaceous-Tertiary 

Composite Total Petroleum System boundary was used from the most recent USGS national oil and gas 

assessment of the basin (Dubiel and others, 2007b, 2011). The USGS recently assessed the Rodessa 

Formation and James Limestone Member of the Pearsall Formation intervals for hydrocarbon resources, 

and the geologic data used in that study (Dubiel and others, 2011, 2012; Warwick, 2011) were 

incorporated into the current CO2 storage assessment and report. The Rodessa Formation (equivalent to 

the lower Glen Rose Formation) and the underlying James Limestone Member, both Early Cretaceous in 

age (figs. 2A and 2B), are composed of interbedded intervals of predominately limestone and carbonate 

mudstone that are locally dolomitized and have variable porosity and permeability (Galloway and others, 

1983; Mancini and others, 2001, 2008a; Montgomery and others, 2002). The rocks within the RodessaJames interval were deposited in back-reef-lagoon, patch-reef, reef, and fore-reef environments that 

developed during the Early Cretaceous sea-level high stands and associated carbonate platform 

depositional environments (McFarlan and Menes, 1991; Yurewicz and others, 1993; Mancini and others, 

2001, 2008a; Kerans and Loucks, 2002). The Rodessa Formation consists of gray, arenaceous, 

argillaceous, oolitic, skeletal limestone interbedded with a few thin sandstone and shale layers (Weeks, 

1938; Roberts and Lock, 1988; Keith and Pittman, 1983). The James Limestone Member is composed of 

lithofacies ranging from deeper water, low-energy wackestones and packstones to shallower water, higher

energy hydrozoa/cryptalgal stromatolite bindstones and requinid/coral packstones, grainstones, and 

boundstones (Loucks and others, 1996). Reservoir rock characteristics within both intervals are associated 

with rudist reef facies composed of grainstones, boundstones, and patch reef distributions controlled by 

salt or other paleostructural highs, creating a combination of stratigraphic and structural traps (Galloway 

and others, 1983; Loucks and others, 1996; Petty, 1999). Some of these areas have developed significant 

secondary moldic porosity from subaerial exposure and dissolution by meteoric diagenesis. Platform 

patch reef and reef development along the Lower Cretaceous shelf break have been the targets for 

petroleum exploration since the early part of the twentieth century (Sams, 1982; Galloway and others, 

1983; Keith and Pittman, 1983; Petty, 1999; Mancini and others, 2001, 2008a; Loucks, 2002; 

Montgomery and others, 2002; Kerans and Loucks, 2002).

The sealing unit for the Rodessa Formation and James Limestone standard and deep SAUs is the 

Ferry Lake Anhydrite (also Lower Cretaceous; figs. 2A and 2B; Pittman, 1985; Petty, 1995). The Ferry 

Lake Anhydrite is composed of alternating intervals of limestone, claystone, gypsum, and anhydrite of 

variable thickness, with individual beds ranging from a few feet near the outcrop to tens of feet thick in 

the central part of the depositional area in northeastern Texas and northwestern Louisiana. Some 

anhydrite intervals can be correlated across several States (Pittman, 1985). The Ferry Lake and its 

equivalent intervals outcrop in southern Arkansas and extend into the subsurface across northeastern 

Texas, northern Louisiana, southern Mississippi, southern Alabama, and the Florida panhandle. In 

southern Florida, the Ferry Lake has been correlated with the Punta Gorda Formation (Pittman, 1985).

The total Ferry Lake Anhydrite thickness ranges from about 50 ft near the northern outcrop belt to more 

than 400 ft in northeastern Louisiana, and thins basinward to about 200 ft before it merges with the Glen 
27

Rose Lower Cretaceous shelf margin (Forgotson, 1963; Keith and Pittman, 1983; Pittman, 1985; Petty, 

1995).

The Rodessa Formation and James Limestone SAU C50490110 and Rodessa Formation and 

James Limestone Deep SAU C50490111 boundaries are based on the depth from the land surface to the 

top of the Rodessa Formation interval, and define three areas where the top of the SAU is either between 

3,000 and 13,000 ft, or 13,000 ft and greater (fig. 8). The Rodessa Formation and James Limestone 

standard and deep SAU areas were determined from formation tops in the IHS Energy Group (2010) 

commercial database and by georeferencing and digitizing lithofacies maps of the interval by Forgotson 

(1963). The gross thickness of the Rodessa Formation and James Limestone Member in the area of the 

SAUs ranges from 450 to 900 ft, with a most-likely thickness of 600 ft for the standard SAU and 700 ft 

for the deep SAU (data from IHS Energy Group, 2010). Available data (Forgotson, 1963; Galloway and 

others, 1983; Esposito and others, 2008; Webster and others, 2008; IHS Energy Group, 2010; and 

Nehring Associates, Inc., 2010) suggest the net-porous interval for both Rodessa Formation and James 

Limestone SAUs ranges from 30 to 115 ft, with a most-likely value of 40 ft.

Data from Galloway and others (1983) and Nehring Associates, Inc. (2010) suggest porosity for

the net-porous interval of the Rodessa Formation and James Limestone standard SAU ranges from 

12 percent to 20 percent, with a most-likely value of 16 percent. For the Rodessa Formation and James 

Limestone deep SAU, the porosity ranges from 6 percent to 13 percent, with a most-likely value of 

10 percent. Permeability of the Rodessa Formation and James Limestone standard SAU is primarily in the 

range of less than 0.2 mD to 2,000 mD, with about 70 mD for the most-likely value (Nehring Associates, 

Inc., 2010). Permeability of the Rodessa Formation and James Limestone deep SAU is estimated to be in 

the range of less than 0.05 mD to 100 mD, with about 10 mD for the most-likely value (Nehring 

Associates, Inc., 2010).

Water-quality data (Breit, 2002; USGS, 2010) suggest that there is a mix of both fresh (TDS 

<10,000 mg/L) and saline water (TDS >10,000 mg/L) within the SAU intervals. For the Rodessa 

Formation and James Limestone standard SAU, approximately 80 percent (the most-likely value; with a 

minimum of 80 percent and maximum of 100 percent) of the area volume may contain saline water 

suitable for subsurface storage of CO2. For the Rodessa Formation and James Limestone deep SAU, 100 

percent (the most-likely value; with a minimum of 100 percent and maximum of 100 percent) of the area 

volume may contain saline water.

Approximately 1 percent of the area for the Rodessa Formation and James Limestone standard and 

deep SAUs is estimated to contain structural and stratigraphic closures associated with patch- or barrierreef development; therefore, 1 percent of the SAU area may be used to estimate the size of the SAUs pore 

buoyant volume. The attributes described herein will be used in accordance with the USGS Carbon 

Sequestration Assessment Methodology (Brennen and others, 2010) to calculate the available storage 

space for CO2 within the Rodessa Formation and James Limestone standard and deep SAUs.
28

Figure 8. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Rodessa Formation and James Limestone and Rodessa 

Formation and James Limestone Deep SAUs in the U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well 

database (IHS Energy Group, 2011) that have penetrated the reservoir formation top.
29

Fredericksburg Group and Rusk Formation SAU C50490112

Edwards, Glen Rose, and James Limestones SAU C50490113

Washita and Fredericksburg Groups, Rusk Formation, and James Limestone SAU 

C50490114

Washita and Fredericksburg Groups, Rusk Formation, and James Limestone 

Deep SAU C50490115

By Sean T. Brennan

The SAUs discussed in this section are comprised of Lower Cretaceous deposits that occur within 

the western U.S. Gulf Coast (fig. 1). Because there is significant overlap within the strata of the SAUs, the 

delineation of which strata are within a given SAU is based on the extent of the overlying regional seal. 

This introductory section describes only the depositional setting during the Early Cretaceous and provides 

a description of the strata therein (fig. 2B) and is followed by descriptions of the individual SAUs and 

their characteristics in subsequent chapters. 

These Lower Cretaceous SAUs are all located almost entirely within the State of Texas (figs. 9‒

11), and within these specific SAUs the formations were deposited in a broad platform in the north-central 

through the southern margins and basins on the eastern and southwestern margins. These basins were the 

Maverick Basin to the southwest, which is located within the Rio Grande embayment, and the East Texas 

Basin to the east (fig. 1; Rose, 1972; Galloway, 2008). The platform was once the Central Texas Platform 

and the southern margin was the Comanchean (Aptian and Albian) Cretaceous reef trend (Rose, 1972), 

which was dominated by the Stuart City reef trend during the Early Cretaceous (Bebout and Loucks, 

1974; Scott, 1990; Galloway, 2008). 

The strata within these SAUs are Aptian to Albian in age (Mancini and others, 2008b), and all lie 

stratigraphically above the Hosston and Sligo Formations (fig. 2B). The deposition of the Sligo Formation 

terminated with relative sea level rise, leading to deposition of the deep water Pine Island Shale Member 

of the Pearsall Formation (Galloway, 2008). This rise in relative sea level was followed by a brief 

shoaling event, which was on the order of one to two million years (Galloway, 2008) leading to the 

deposition of the James Limestone Member of the Pearsall Formation (also referred to as the Cow Creek 

Limestone in the Maverick Basin region; Loucks, 2002). James Limestone Member deposition was 

terminated by another relative sea level rise, which led to the deposition of the Bexar Shale Member of 

the Pearsall Formation (Galloway, 2008). There is evidence of shoaling facies within the James 

Limestone and Bexar Shale Members that are composed of packstones and grainstones, which, due to 

diagenetic leaching of carbonate grains, has created high-porosity zones within these otherwise finegrained, low-porosity rocks (Galloway, 2008). 

During the flooding event that led to the deposition of the Bexar Shale Member, the Stuart City 

reef trend began to establish itself along the drowned Sligo reef trend (Bebout and Loucks, 1974; Scott, 

1990; Galloway, 2008). This reef trend wrapped around the Maverick Basin (Rose, 1972; Talbert and 

Atchley, 2000) and is referred to as the Devils River trend along the northern border of the basin (Rose, 

1972; Loucks, 2002; Galloway, 2008), creating a restricted basin that was bounded on the southern, 
30

eastern, and northern margins by the reef (Winker and Buffler, 1988) and along its eastern edge by the 

Central Texas Platform (Galloway, 2008). 

Within the SAUs, the Glen Rose Limestone overlies the Pearsall Formation (fig. 2B). In the 

western Gulf Coast, the Glen Rose Limestone is divided into lower and upper parts, with the lower part of 

the Glen Rose Limestone equivalent to the Rodessa Formation and Ferry Lake Anhydrite of the central 

and eastern Gulf Coast (Imlay, 1945), and the upper part of the Glen Rose Limestone equivalent to the 

Rusk and Mooringsport Formations of the central and eastern Gulf Coast (fig. 2B; Forgotson, 1963). In 

the East Texas Basin and eastward from that basin, the upper and lower Glen Rose Limestone are 

separated by a massive anhydrite within the Ferry Lake Anhydrite (Galloway, 2008). This anhydrite 

forms the regional seal for the Rodessa Formation and James Limestone SAU C50490110 and the 

Rodessa Formation and James Limestone Deep SAU C50490111 (fig. 8; also see Rodessa Formation and 

James Limestone SAU of this chapter). Within the regions outlined by SAUs C50190110 and C50490110 

(fig. 8), the Rodessa Formation and James Limestone Member are excluded from the SAUs described in 

this section. 

The facies of the lower Glen Rose Limestone represent back-reef depositional environments that 

exhibit fabrics from mudstones through grainstones. This variation in the limestone leads to varied zones 

of high porosity within the formation. Furthermore, there are patch reefs common within the lower Glen 

Rose Limestone in the Maverick Basin (Scott, 2004; Aconcha, 2008). These patch reefs are 

approximately 35 m high, with diameters of about 1 kilometer (Aconcha, 2008). High-porosity zones 

within the James Limestone Member are common within the patch reefs (Scott, 2004; Aconcha, 2008). 

Although the upper Glen Rose Limestone is similar to the lower Glen Rose Limestone, patch-reefs are not 

present (Kerans and Loucks, 2003). However, diagenetically altered dolomite zones (Scott, 2004) that 

may result from hydrothermal alteration (Loucks and Kerans, 2003) are similar in shape to the patchreefs. These zones are approximately 30 ft high with areal extents similar to the patch-reefs (Loucks and 

Kerans, 2003; Scott, 2004). 

The deposition of the Glen Rose Limestone was terminated by a relative rise in sea level, followed 

by deposition of Fredericksburg Group-age strata, which consist of a combination of carbonate and 

siliciclastic deposits. The siliciclastic deposits overlie the upper Glen Rose Limestone primarily in the 

East Texas Basin (Galloway, 2008) and are the result of terrigenous influx from the progradation of a 

deltaic complex sourced from the Arbuckle-Ouachita uplift (Seni, 1981) into the northern shore of the 

East Texas Basin (Galloway, 2008). These clastic sediments form the Paluxy Formation. While the 

Paluxy Formation was deposited within the northern East Texas Basin along the southern margin, the 

back-reef/shelf sediments of the Edwards Limestone were being deposited. The limestone units of the 

Fredericksburg depositional event comprise predominantly low-porosity limestones interspersed with 

some high-porosity zones (Dyer and Bartolini, 2004). The Paluxy Formation was overlain by the 

transgressive shelf carbonates of the Edwards Limestone and the equivalent Goodland Limestone 

(Galloway, 2008), which is a low-porosity limestone. During this time, the Maverick Basin became 

highly restricted, which led to the deposition of the evaporitic McKnight Formation (Galloway, 2008). 

Additionally, the clay-rich, deep-water Kiamichi Formation was being deposited in the East Texas Basin 

and the Maverick Basin (Galloway, 2008). The Kiamichi Formation alone forms the regional seal for the 

Fredericksburg Group and Rusk Formation SAU C50490112 in the East Texas Basin, whereas the 

Kiamichi and McKnight Formations form the regional seal for the Edwards, Glen Rose, and James 

Limestones SAU C50490113 in the Maverick Basin. The Kiamichi Formation is not thick enough, nor 

consistently present, over the entire Central Texas platform to be considered a regional seal, which is why 

it is only recognized as a regional seal within the East Texas and Maverick Basins. 
31

The Fredericksburg Group depositional event is overlain by the deposits of the Washita Group 

depositional event (Galloway, 2008). The major unit at the base of the Washita Group that overlies the 

Fredericksburg deposits is the Georgetown Limestone. The Washita Group deposits are broadly similar to 

the underlying Fredericksburg carbonate units, though with more shale intercalated with the carbonates 

(Galloway, 2008). The Washita Group deposits consist of widespread platform carbonates bounded to the 

south by the continued aggradation of the Stuart City reef trend (Galloway, 2008). The shoaling along the 

back-reef continued to be a locus of grainstone deposition, and subsequent diagenetic activity created 

highly porous zones in this region (Mancini and Scott, 2006). The Georgetown Limestone is overlain by 

the Grayson Shale and Del Rio Clay, also of the Washita Group, which are clay-rich units that form the 

regional seal for the Washita and Fredericksburg Groups, Rusk Formation, and James Limestone SAU 

C50490114 and the Washita and Fredericksburg Groups, Rusk Formation, and James Limestone Deep 

SAU C50490115. 

Fredericksburg Group and Rusk Formation SAU C50490112

The Fredericksburg Group and Rusk Formation SAU C50490112 is located entirely within the 

East Texas Basin of the U.S. Gulf Coast (fig. 9). The regional seal is the clay-rich Kiamichi Formation 

(Dennen and Hackley, 2012) that is described as a distal turbiditic deposit (Scott and others, 1975). The 

Kiamichi Formation is between 10 and 150 ft thick in outcrops throughout the U.S. Gulf Coast region 

(Hill, 1891; Wilmarth, 1938; Leggat, 1957; Shelburne, 1959; Fox and Hopkins, 1960; Perkins, 1960; 

Freeman, 1964; Barnes, 1967a,b, 1972; Brown, 1971) and is 90 ft thick in the subsurface along the 

western margin of the East Texas Basin (Branson, 1950). The area of the SAU is approximately 

16,600,000 acres and is based on the extent and depth of the base of the Kiamichi Formation. 

The reservoir strata below the Kiamichi Formation that are within this SAU include the 

Fredericksburg Group and the Rusk Formation. Within the East Texas Basin, the Fredericksburg Group is 

composed of the Goodland Limestone, the Edwards Limestone, the Walnut Clay, and the Paluxy 

Formation (fig. 2B; Mancini and others, 2008b; Galloway, 2008). The Edwards Limestone is 

predominantly present in the southern region of the SAU, along the Stuart City reef trend (Galloway and 

others, 1983), whereas the Paluxy Formation is thickest in the northern region of the SAU, where the 

delta front prograded into the East Texas Basin, sourced from the Arbuckle-Ouachita uplift to the north 

(fig. 1; Seni, 1981; McFarlan and Menes, 1991; Galloway, 2008). The deeper water Goodland Limestone 

overlies the Paluxy Formation and becomes thicker northward as the clastic input from the Paluxy delta 

decreased (Galloway, 2008). The thickness of this depositional package ranges between 1,300 and 2,300 

ft within the Fredericksburg Group and Rusk Formation SAU C50490112.

The extent of the stratigraphic components of the Fredericksburg Group and Rusk Formation SAU 

C50490112, and the patchy distribution of the porous zones within the carbonates, made it difficult to 

estimate the net-porous thickness of the SAU. The percentage of the SAU where either formations were 

present, or where shoals were likely to be found, were used to decrease the thickness of those porous units 

to arrive at a reasonable range of thicknesses that best represented the range of potential average values. 

Specifically, the net-porous thickness was assumed to range between 100 and 250 ft across the East Texas 

Basin. The range of porosity values within the various facies of the SAU made determining the range of 

average porosity difficult because the porosity within the Paluxy Formation sandstones is significantly 

higher than the porosity of the shoaling facies within the limestone units. Since the net-porous thickness 

within the Fredericksburg Group and Rusk Formation SAU C50490112 is dominated by the Paluxy 

Formation, the porosity values were skewed to the higher side, ranging from 10 to 18 percent and 

favoring the values of the Paluxy Formation (Nehring Associates, Inc., 2010). The permeability values 

ranged from 0.1 to 4,000 mD, with a central tendency value of 100 mD (Nehring Associates, Inc., 2010). 
32

Water-quality data indicate that all formations within this SAU contain waters with salinity values in 

excess of the 10,000 ppm TDS threshold (Breit, 2002). Buoyant-storage values were based on both 

produced volumes and known reserves of oil and gas (Nehring Associates, Inc., 2010); undiscovered 

resource estimates (Dubiel and others, 2011); and estimates of the areas and thicknesses of structural, 

stratigraphic, and diagenetic traps.
33

Figure 9. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Fredericksburg Group and Rusk Formation SAU in the 

U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have 

penetrated the reservoir formation top.
34

Edwards, Glen Rose, and James Limestones SAU C50490113 

The Edwards, Glen Rose, and James Limestones SAU C50490113 is located entirely within the 

Maverick Basin and within the westernmost portion of the U.S. Gulf Coast (fig. 10). The regional sealing 

units for the SAU are the McKnight Formation, a 100- to 150-ft thick argillaceous, evaporitic unit 

(Galloway, 2008; Dennen and Hackley, 2012) and the Kiamichi Formation (fig. 2B). The area of the SAU 

is 3,500,000 acres, which is defined by the extent (Dennen and Hackley, 2012) and depth (IHS Energy 

Group, 2010) of the McKnight Formation. 

The strata below the McKnight and Kiamichi Formations in the Edwards, Glen Rose, and James 

Limestones SAU C50490113 are the Edwards Limestone, which is thickest along the southern edge of the 

Maverick Basin, near the Stuart City reef trend (Galloway, 2008); the Glen Rose Limestone, which also 

thickens near the Stuart City reef trend; and the Pearsall Formation, which contains the Pine Island Shale, 

Cow Creek Limestone (and its correlative James Limestone Member), and Bexar Shale Members. The 

average total thickness of this stratigraphic package ranges from 2,400 to 3,900 ft. The irregular 

distribution of porous zones within the limestone units of the SAU made estimation of the average netporous thickness problematic. The porous zones primarily exist in the patch reefs of the Glen Rose 

Limestone, the shelfward shoals of the Pearsall Formation members (primarily the Cow Creek Limestone 

and Bexar Shale Members), and the porous back-reef deposits of the Edwards Limestone. The thickness 

of these porous zones, coupled with the likely percentage of the SAU that each covered, was used to 

estimate the average net-porous thickness across the SAU. The average porosity of these net-porous zones 

is estimated to range from 5 to 15 percent (Nehring Associates, Inc., 2010). The permeability values are 

estimated to range from 0.01 to 500 mD, with a central tendency value of 4 mD (Nehring Associates, Inc., 

2010). Water-quality data indicate that all formations within the Edwards, Glen Rose, and James 

Limestones SAU C50490113 contain waters with salinity values in excess of the 10,000 ppm TDS 

threshold (Breit, 2002). Buoyant-storage values were based on known oil and gas reserve values (Nehring 

Associates, Inc., 2010);undiscovered resource estimates (Dubiel and others, 2011); and estimates of the 

areas and thicknesses of structural, stratigraphic, and diagenetic traps.
35

Figure 10. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Edwards, Glen Rose, and James Limestones SAU in the 

U.S. Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have 

penetrated the reservoir formation top.
36

Washita and Fredericksburg Groups, Rusk Formation, and James Limestone SAU 

C50490114 and Washita and Fredericksburg Groups, Rusk Formation, and James 

Limestone Deep SAU C50490115

The Washita and Fredericksburg Groups, Rusk Formation, and James Limestone SAU C50490114 

and Washita and Fredericksburg Groups, Rusk Formation, and James Limestone Deep SAU C50490115 

(hereafter the “standard” and “deep” SAUs, respectively) extend from the eastern edge of East Texas 

Basin, across the Central Texas platform, and to the western edge of the Maverick Basin (fig. 11). The 

regional sealing units for the SAUs are the clay-rich, fossiliferous Grayson Shale and Del Rio Clay, which 

combined are 80 to 100 ft thick in the area of the SAUs (Dennen and Hackley, 2012). The areas are 

24,100,000 acres and 4,110,000 acres for the standard and deep SAUs, respectively. The extent of the 

standard SAU is defined by the extent and depth to the base of the Grayson Shale and Del Rio Clay (IHS 

Energy Group, 2010; Dennen and Hackley, 2012). The depth of the standard SAU ranges from 3,000 to 

13,000 ft, and the top of the deep SAU ranges from 13,000 to 17,100 ft deep (IHS Energy Group, 2010). 

The stratigraphic units that compose the Washita and Fredericksburg Groups, Rusk Formation, 

and James Limestone SAU C50490114 and Washita and Fredericksburg Groups, Rusk Formation, and 

James Limestone Deep SAU C50490115 consist of the entire Lower Cretaceous package of rock 

discussed in the introduction above. However, this total stratigraphic package is only considered within 

the Central Texas platform because there are additional regional seals below the Grayson Shale and Del 

Rio Clay in the Maverick and East Texas Basins. Therefore, within these small basins, the strata included 

within these SAUs are the Georgetown Limestone of the Washita Group and any equivalent strata. Using 

these parameters, it was determined that the average gross thickness of the SAUs ranges from 400 to 700 

ft for the standard SAU and 800 to 1,400 ft for the deep SAU. 

The net-porous thickness primarily comes from the porous zones within the Georgetown 

Limestone and any equivalent units (Mancini and Scott, 2006), with some contribution from the Edwards 

Limestone near the Stuart City reef trend and the patch reefs of the Glen Rose Limestone. The average 

net-porous-thickness values calculated from the thickness and distribution of the porous intervals of these 

formations indicate that the thickness for the standard SAU ranges from 30 to 120 ft, and the deep SAU 

ranges from 50 to 150 ft. The average porosity for the net-porous intervals is 5 to 15 percent for the 

standard SAU and 2 to 8 percent for the deep SAU (Nehring Associates, Inc., 2010). The permeability 

ranges from 0.1 to 100 mD, with a central tendency of 5 mD for the standard SAU, and from 0.1 to 10 

mD, with a central tendency of 1 mD for the deep SAU (Nehring Associates, Inc., 2010). Water-quality 

data indicate that all formations within the Washita and Fredericksburg Groups, Rusk Formation, and 

James Limestone SAU C50490114 and Washita and Fredericksburg Groups, Rusk Formation, and James 

Limestone Deep SAU C50490115 contain waters with salinity values in excess of the 10,000 ppm TDS 

threshold (Breit, 2002). Buoyant-storage values were based on known oil and gas reserve values (Nehring 

Associates, Inc., 2010); undiscovered resource estimates (Dubiel and others, 2011); and estimates of the 

areas and thicknesses of structural, stratigraphic, and diagenetic traps.
37

Figure 11. Map of the U.S. Geological Survey storage assessment unit (SAU) boundaries for the Washita and Fredericksburg Groups, Rusk Formation, 

and James Limestone and Washita and Fredericksburg Groups, Rusk Formation, and James Limestone Deep SAUs in the U.S. Gulf Coast. Grid cells 

(one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation 

top.
38

Tuscaloosa and Woodbine Formations SAU C50490116

By Ronald M. Drake II

The Woodbine Formation in Texas and the Tuscaloosa Formation in Louisiana are laterally 

equivalent units composed of interbedded conglomerate, sandstone, and shale (Pitman and others, 2007).

In Louisiana, the upper part of the Tuscaloosa Formation is predominantly a marine shale unit that forms 

the regional seal for the reservoirs within the lower part of the Tuscaloosa Formation. These upper 

Tuscaloosa Formation shales correlate with the marine shales of the Eagle Ford Group in Texas, which 

overlies the Woodbine Formation and forms the regional seal for the underlying Woodbine Formation 

reservoirs. The marine shales of the Eagle Ford Group and upper Tuscaloosa Formation are 120 to 800 ft 

thick (U.S. Department of Energy, 2011).

The boundaries for the Woodbine and Tuscaloosa Formations SAU C50490116 are based upon 

interpretations of formation-top picks from a commercial database (IHS Energy Group, 2010) that are 

between 3,000 and 13,000 ft below the surface and from the Cretaceous shelf margin as depicted from 

Galloway and others (1991), which marks the southern boundary of the SAU. Within the Woodbine and 

Tuscaloosa Formations SAU C50490116, the average depth to the top of the SAU is 5,165 ft. The area of 

the SAU is about 82,823,000 acres. The most common formation thickness ranges from 450 to 800 ft and 

the most-likely thickness is 600 ft. The net-porous-sand thicknesses were determined by applying a netto-gross ratio of 1:4, as determined from geophysical logs, and from the net-sand map provided in Petty 

(1997). Average net-porous-interval thickness ranges from 100 to 250 ft, and the most-likely net-porous 

thickness is 150 ft.

Porosity and permeability data were obtained from a proprietary database (Nehring Associates, 

Inc., 2010) and the 1995 USGS national oil and gas assessment report (Schenk and Viger, 1995a). The 

most-likely porosity values for the Woodbine and Tuscaloosa Formations SAU C50490116 are 15‒29 

percent, with a mode of 25 percent. Average permeabilities for the Woodbine and Tuscaloosa Formations 

SAU C50490116 range from 0.2 mD to 5,000 mD, with a most-likely value of 200 mD.

Water-quality data were compiled from several sources, including the USGS National Water 

Inventory System database and the produced-water database of “Breit” (2002). The water-quality data for 

the Woodbine and Tuscaloosa Formations were plotted on a map of the SAU, and areas were identified 

within the SAU that contained high concentrations of TDS. The results show that areas with high TDS 

(>10,000 mg/L) measurements are intermixed with areas of low TDS (<10,000 mg/L) measurements 

within the Woodbine and Tuscaloosa Formations; however, data indicate that the majority of the SAU 

(about 95 percent) contains pore water with TDS values that are greater than 10,000 mg/L.

In order to calculate the maximum buoyant pore volume within structural and stratigraphic 

closures for the Woodbine and Tuscaloosa Formations SAU C50490116, the known closure areas from 

the highly productive regions located throughout the SAU were extrapolated and combined with upper 

bounds on regional reservoir thickness and porosity. The known closure areas were calculated by 

summing petroleum reservoir areas for the SAU (Nehring Associates, Inc., 2010). An assumption 

underlying this calculation is that there is potential for additional uncharged or undiscovered structural 

and stratigraphic closures outside of regions of historical hydrocarbon production.

The boundaries, thicknesses, rock properties, and water-quality information mentioned above will 

be used in accordance with the USGS Carbon Sequestration Assessment Methodology (Brennan and 

others, 2010) to calculate the available storage space within the Woodbine and Tuscaloosa Formations 

SAU C50490116.
39

Figure 12. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Woodbine and Tuscaloosa Formations SAU in the U.S. 

Gulf Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated 

the reservoir formation top.
40

Navarro, Taylor, and Austin Groups SAU C50490117

By Ernie R. Slucher

The Upper Cretaceous Navarro, Taylor, and Austin Groups SAU C50490117 is a composite 

assessment unit containing multiple formations with potential storage reservoirs in the subsurface of the 

U.S. Gulf Coast. In most areas of the SAU west of the Mississippi River, the Navarro, Taylor, and Austin 

Groups are formally recognized, whereas in eastern areas, comparable rocks are mainly in the Eutaw 

Formation and Selma Group (fig. 2C). Overall, rocks within the SAU chronicle a period of relative sealevel highstand, with some eustacy fluctuation, when both marine carbonate-dominated and nonmarine 

and marine clastic-dominated depositional systems occurred. Regional deposition patterns during this 

time reflect mainly crustal subsidence and uplifts, loading subsidence in subbasins, and local plutonic and 

volcanic events in response to Laramide tectonics and overall motion of the North American tectonic 

plate (King, 1994; Galloway, 2008; Mancini and others, 2008b; Pearson, 2010). Potential storage units 

within the SAU vary based upon location within the Gulf Coast. For instance, in the Rio Grande 

embayment area of Texas (figs. 1, 2C, and 13), stratigraphic units included in the SAU are the Anacacho 

Limestone and San Miguel Formation of the Taylor Group and the Olmos and Escondido Formations of 

the Navarro Group. In the Houston embayment region, units consist mainly of the Tokio Formation and 

the informal Blossom Sand “D” unit of the Austin Group (as identified in the IHS Energy 2011 dataset), 

as well as the informal sub-Clarksville sand (Condon and Dyman, 2003)—the latter, even though it occurs 

below the Austin Group, is at the top of the Eagle Ford Shale, which is the seal of the immediately

underlying Tuscaloosa and Woodbine Formations SAU, and could not be included in that assessment (see 

Tuscaloosa and Woodbine Formations SAU C50470116, this volume; figs. 1, 2C, and 13). In the region 

of the Mississippi embayment, the Eutaw Formation, “Monroe gas rock” and “Jackson gas rock” of local 

usage (Fergus, 1935; Saunders and Harrelson, 1992), and the Tokio Formation of the Austin Group are 

potential storage units (figs. 1, 2C, and 13). Collectively, most storage potential in the SAU is within 

deltaic, shoreface, and marine-shelf-sandstone portions of the Olmos and Escondido Formations of the 

Navarro Group, the San Miguel Formation of the Taylor Group, the Blossom Sand “D” unit of the Austin 

Group, the Eutaw Formation, and the sub-Clarksville sand (Dubroff, 1987; Ewing, 2009a; Nehring 

Associates, Inc., 2010). Subordinate storage potential exists locally in shoaling shelf-carbonate rocks of 

the Anacacho Limestone (C. Swezey, USGS, written commun., 2011) and “Monroe gas rock,” and where 

shoal/reefal carbonate and tuffaceous rocks of the “Jackson gas rock” and Anacacho Limestone formed in 

areas over igneous plutons or around volcanic vents of Campanian and Maastrichtian age (Ewing and 

Caran, 1982; Harrelson, 1989; Ewing, 2009b). The thick, widespread, and clay-rich Midway Group 

overlies the uppermost units of the SAU throughout its extent, forming the regional seal. The Midway 

Group is a transgressive unit deposited during a period of reduced sediment influx to the Gulf Coast 

(Salvador, 1991a).

The Navarro, Taylor, and Austin Groups SAU C50490117 encompasses approximately 

45,262,000 acres that occur between 3,000 and 13,000 ft below the surface, with the most-likely depth to 

the top of the SAU being approximately 5,250 ft. The boundary, thickness, and petrophysical properties 

of the SAU were defined and categorized primarily by IHS Energy Group (2010, 2011) data on the top of 

the Navarro Group or equivalent chronostratigraphic units; the distribution of stratigraphic units with 

storage potential across the region; and other available data resources (Snedden and Kersey, 1982; 

Dubroff, 1987; Tyler and others, 1987; Bebout and others, 1992; Clark, 1995; Greer, 1995; Condon and 

Dyman, 2003; Collins, 2008; Ewing, 2009a; Nehring Associates, Inc., 2010; P. Nelson, USGS, written 
41

commun., 2011). These data indicate the most-likely range of total SAU thickness is from 1,000 to 2,200 

ft, with 1,600 ft being the regional average. Accessed data suggest that porous intervals of the SAU in 

total have a minimum, maximum, and most likely net-porous thickness that is available for potential 

storage of CO2 of 50, 150, and 100 ft, respectively. Porosity and permeability values within the SAU vary 

spatially across the SAU because of the multiplicity of formations representing various depositional 

environments composing the interval. Nevertheless, petrophysical data obtained on all units identified as a 

potential storage reservoir within the SAU indicate overall mean porosity values range from 12 to 26 

percent, with 21 percent being the most likely, and permeability values range from 0.1 to 600 mD, with a 

most-likely value of 250 mD. 

The methodology defined by Brennan and others (2010) was used to determine the minimum and 

central tendency buoyant trapping pore volumes. The maximum buoyant-trapping pore volume is based 

on (1) the combined area of structural reservoir traps at the top of the SAU, as interpreted mainly from 

data obtained from IHS Energy Group (2010, 2011); (2) the maximum net-porous interval thickness; (3) 

the maximum mean porosity value; and (4) known petroleum production and projected resource estimates 

(Condon and Dyman, 2003; Nehring Associates, Inc., 2010; Dubiel and others, 2011). 

Data on salinity of groundwater within the Navarro, Taylor, and Austin Groups SAU C50490117

suggest TDS values exceed 10,000 mg/L throughout most of the region (Breit, 2002; Kharaka and Hanor, 

2007); however, some regional studies (Nordstrom, 1982; Webb, 1984; Miller, 1990) suggest areas of low 

salinity may exist locally along the updip margin of the SAU, thus limiting the most-likely area available 

for CO2 storage by about 5 percent.
42

Figure 13. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Navarro, Taylor, and Austin Groups SAU in the U.S. Gulf 

Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the 

reservoir formation top.
43

Carrizo Sand and Wilcox Group SAU C50470118

By Matthew D. Merrill

The Carrizo Sand and Wilcox Group form an SAU that contains thick sand sequences of nearshore 

and deltaic deposits. According to Galloway (1968), numerous principal-component facies of delta 

systems are exhibited in the formations, ranging from bar sands, mud and silt-bay facies, channels, prodelta muds, deltaic-plain, destructional-phase marine transgressive sand, and mud-lignite facies. Source 

material for the sediments originated in the southern Rocky Mountains and Great Plains and entered the 

U.S. Gulf Coast at the Houston embayment on the west (Galloway and others, 1991) and flowed from 

Appalachian Mountains and entered the U.S. Gulf Coast on the east (Adams, 1928; Galloway, 2008). The 

Carrizo Sand and Wilcox Group SAU (fig. 2D) extends from Texas to Alabama (fig. 14) and is sealed by 

a thick, regional seal that consists of the shales of the Reklaw, Cane River, and Tallahatta Formations 

(fig. 2D). The Paleocene lower part of the Wilcox Group and Eocene upper part of the Wilcox Group are 

separated by the Big Shale Member in portions of south Texas, Louisiana, and Mississippi (fig. 2D; 

Galloway, 1968; Tye and others, 1991). The continuous extent of the Big Shale Member is limited to 

central Louisiana and Mississippi; middle Wilcox Group shales in Texas are generally valley-fill deposits 

that are not correlative across the U.S. Gulf Coast (Dingus and Galloway, 1990; Echols and Goddard, 

1992). In keeping with the regional- to basinal-scale defined in the methodology, the middle Wilcox

Group shales are not included as confining layers, and both the lower and upper parts of the Wilcox 

Group and Carrizo Sand (and their equivalents in Mississippi; Fillon and others, 1998) are included in the 

same SAU. 

The Carrizo Sand and Wilcox Group SAU C50470118 has an area of about 36,695,000 acres 

(fig. 14). The boundaries of the SAU are as follows: the northern boundary of the SAU is the 3,000-ft 

depth-to-Wilcox contour; the western edge is the Texas and Mexico international border; the eastern edge 

is the State-waters line in western Alabama and all of coastal Mississippi and easternmost Louisiana; and 

the southern boundary of the SAU is an interpolated 13,000-ft depth-to-Wilcox contour. In the western 

Gulf Coast region, 41,000 individual depth-to-top-of-interval records were employed to produce the 

boundary of the 3,000- to 13,000-ft depth-to-top of the SAU (IHS Energy Group, 2011). Additionally, 

interval top-depths from 4,400 of these records were used to create an isopach map that indicates the SAU 

has a range of average gross thicknesses that is from 3,000 to 5,000 ft, with a most-likely value of 4,000 

ft. Combining published net-sand isopachs of various reservoir intervals resulted in a net-porous thickness 

map for the SAU that has an average range of 600 to 1,400 ft, centered on 900 ft (Galloway, 1968; Fisher 

and McGowen, 1969; Hamlin, 1983; Tye and others, 1991; Tyler and Scott, 1999). Average porosity for 

the sands in the reservoir intervals of the SAU ranges from 16 to 28 percent (Grubbs, 1953; Nehring 

Associates, Inc., 2010) and permeability ranges from 0.1 to 1,200 mD, with most likely values around 

20 percent and 70 mD, respectively (Nehring Associates, Inc., 2010). Salinity maps from Pettijohn and 

others (1988) and data from the USGS produced-water database (Breit, 2002) covered the majority of the 

SAU and revealed that much of the SAU is greater than the 10,000 mg/L TDS limit for CO2 storage 

consideration; however, approximately 15 percent of the area of the SAU may incorporate areas of fresh 

water (TDS <10,000 mg/L).

In order to calculate the maximum buoyant pore volume within structural and stratigraphic 

closures for the Carrizo Sand and Wilcox Group SAU C50470118, the known closure areas from the 

highly productive regions located throughout the SAU were extrapolated and combined with upper 
44

bounds on regional reservoir thickness and porosity. The known closure areas were calculated by 

summing petroleum reservoir areas for the SAU (Nehring Associates, Inc., 2010). An assumption 

underlying this calculation is that there is potential for additional uncharged or undiscovered structural 

and stratigraphic closures outside of regions of historical hydrocarbon production.
45

Figure 14. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Carrizo Sand and Wilcox Group SAU in the U.S. Gulf 

Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the 

reservoir formation top.
46

Queen City Sand SAU C50470119

By Matthew D. Merrill

The middle Eocene Queen City Sand is a deltaic and strand-plain sandstone unit that exists in the 

subsurface of the Texas Gulf Coast region, occurring between the more massive Sparta Sand and sands of 

the Wilcox Group (fig. 2D). Guevara and Garcia (1972) describe the Queen City Sand as a sandy, nonfossiliferous to sparsely fossiliferous unit. In south Texas, the sands represent a highly destructive delta 

facies, whereas in east Texas they represent a highly constructive delta facies. In central Texas, the Queen 

City Sand represents a strand-plain. Guevera and Garcia (1972) and Hobday and others (1979) provide 

detailed discussions of facies groups beyond the three basic environments mentioned above. Facies 

deposition occurred during progradation across shallow shelf muds and glauconitic sands of the Reklaw 

Formation. The Queen City Sand is overlain by similar shales and glauconitic sands of the Weches 

Formation (Guevara and Garcia, 1972), which forms the regional seal for the SAU. Sediment-source areas 

for the Queen City Sand were located primarily to the northwest, though small influxes from the northeast 

were also possible (Hobday and others, 1979). Deposition of this minor terrigenous clastic wedge is 

limited to Texas, as lithologies grade into the shales of the Cane River Formation in western Louisiana.

The Queen City Sand SAU C50470119 covers an area of 13,042,000 acres, (+10 percent) (fig. 

15). The SAU is bounded on the northwestern side by the 3,000-ft depth requirement for an SAU; on the 

southwestern side by the U.S.-Mexico international border; on the southeast side by a zero net-sand 

isopach-line truncation, as determined from Guevara and Garcia (1972); and on the northeast side by the 

extent of the formation. Formation records obtained from the IHS Energy Group (2010) database indicate 

that the regional seal for the SAU, the Weches Formation, is present over the entire SAU.

Depths from surface in the SAU range from 3,000 to 12,500 ft. Mean gross Queen City Sand 

thickness, calculated from well-top-depth differencing, ranges from 600 to 1,400 ft, with most likely 

values around 1,100 ft (IHS Energy Group, 2011). Mean net-sand thicknesses in the SAU, determined 

from isopachs presented in Guevara and Garcia (1972), range from 20 to 150 ft, with a most-likely value 

of 50 ft. Data from 15 producing reservoirs in the Nehring Associates, Inc. (2010) database indicate that 

mean porosity in the net sands ranges from 22 to 30 percent. Permeability data from the same database 

show typical values for deltaic sandstones with an absolute range of 0.1 to 1,200 mD and common values 

around 70 mD.

Water quality in the Queen City Sand SAU C50470119 is both fresh (TDS <10,000 mg/L) and 

saline (TDS >10,000 mg/L). Maps by Pettijohn and others (1988) and produced-waters information from 

Breit (2002) indicate that approximately 60 percent of the area within the SAU contains saline 

groundwater and therefore is a viable CO2 storage option.

In order to calculate the maximum buoyant pore volume within structural and stratigraphic 

closures for the Queen City Sand SAU C50470119, the known closure areas from the highly productive 

regions located throughout the SAU were extrapolated and combined with upper bounds on regional 

reservoir thickness and porosity. The known closure areas were calculated by summing petroleum 

reservoir areas for the SAU (Nehring Associates, Inc., 2010). An assumption underlying this calculation 

is that there is potential for additional uncharged or undiscovered structural and stratigraphic closures 

outside of regions of historical hydrocarbon production.
47

Figure 15. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Queen City Sand SAU in the U.S. Gulf Coast. Grid cells 

(one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation 

top.
48

Sparta Sand SAU C50470120

By Jacob A. Covault

The middle Eocene Sparta Sand is approximately 500 ft thick on average and predominantly 

includes fine-grained, siliciclastic sandstone interbedded with mudstone (figs. 2D and 16; Payne, 1968; 

Ricoy and Brown, 1977; Hackley and Ewing, 2010; Hackley, 2012). The Sparta Sand is the middle part of 

the Claiborne Group, which comprises lower, middle, and upper sandstone reservoirs separated by finergrained units. The relatively fine-grained Weches Formation underlies the Sparta Sand, which is capped 

by the fine-grained Cook Mountain Formation and foresets of the overlying Yegua (in Texas) and 

Cockfield (in Louisiana and Mississippi) Formations (Ricoy and Brown, 1977; Lawless and others, 1997; 

Galloway, 2008; Hackley and Ewing, 2010; Hackley, 2012). The Cook Mountain Formation is relatively 

fine grained and is hundreds of feet thick in east Texas (Wendlandt and Knebel, 1926; Hackley, 2012); 

however, it is characterized as sandstone-rich in south Texas and Mexico (Trowbridge, 1932; Kane and 

Gierhart, 1935). The Cook Mountain Formation and the overlying fine-grained foresets of the Yegua and 

Cockfield Formations form the sealing units for the underlying Sparta Sand. The Sparta Sand and 

overlying Cook Mountain Formation couplet has been interpreted to represent a landward retreat of 

depositional environments from predominantly coarse-grained, deltaic, and barrier-bar systems (Sparta 

Sand) to a finer grained, fully marine system (Cook Mountain Formation) in the Paleogene Gulf of 

Mexico (Ricoy and Brown, 1977; Galloway and others, 2000; Galloway, 2008). The overlying Yegua and 

Cockfield Formations have been interpreted to represent progradation of a fluvial-dominated delta system 

across the submerged Sparta Sand and Cook Mountain Formation (Galloway, 2008). Fine-grained 

mudstone is interpreted to compose the prodelta foresets of the Yegua and Cockfield progradational delta 

system, following the fluvial-dominated delta facies model of Berg (1982).

The Sparta Sand SAU C50470121 is a potential reservoir unit for CO2 storage in the U.S. Gulf 

Coast at subsurface depths from 3,000 to 12,000 ft (fig. 16). The SAU boundary is defined by the 3,000-ft 

drilling depth based on more than 9,000 well penetrations (IHS Energy Group, 2011), the middle Eocene 

Sparta continental-shelf edge defined by Galloway (2005), and the extent of shallow-marine sandstone 

mapped by Ricoy and Brown (1977). The range of total storage formation thickness for the reservoir unit

was determined by tops-differencing from nearly 700 well penetrations of the top of the Sparta Sand to the 

top of the Weches Formation (IHS Energy Group, 2011), as well as by review of regional studies of the 

Sparta Sand (Todd and Roper, 1940; Payne, 1968; Hackley, 2012). The thickness of the net-porous interval 

was determined from net-sandstone to gross-stratigraphic thickness and net-sandstone thickness maps by 

Ricoy and Brown (1977) and Payne (1968). Average porosity ranges from 20 to 35 percent, and average 

permeability ranges from 0.1 to greater than 1,000 mD (Nehring, 1991; Nehring Associates, Inc., 2010).

Water-quality measurements indicate that groundwater in the formation is predominantly saline 

(>10,000 mg/L TDS; Pettijohn and others, 1988; Breit, 2002). The minimum and most likely buoyanttrapping pore volumes were determined using methods described in Brennan and others (2010). 

Maximum buoyant-trapping pore volume was calculated from the product of (1) the combined areas of 

Sparta Sand structural reservoir traps and reservoirs of producing fields (Nehring Associates, Inc., 2010),

(2) the maximum net-porous-interval thickness, and (3) the maximum porosity. Sparta Sand structural 

reservoir traps include rollover anticlines downthrown to growth faults and broad stratal upwarping over 

areas influenced by salt tectonics (Nicot and Havorka, 2009; Hackley, 2012). Combined structuralstratigraphic traps against salt diapirs were not considered as a result of limited subsurface data to 

illustrate closure geometry.
49

Figure 16. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Sparta Sand SAU in the U.S. Gulf Coast. Grid cells (one 

square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation top.
50

Yegua and Cockfield Formations SAU C50470121

By Jacob A. Covault

The middle and upper Eocene Yegua and Cockfield Formations are approximately 700 ft thick on 

average and include siliciclastic sandstone interbedded with mudstone and volcanic ash beds (figs. 2D and 

17) (Galloway, 2008; Hackley, 2012). The Yegua and Cockfield Formations compose the uppermost part 

of the Claiborne Group, which comprises lower, middle, and upper sandstone reservoirs separated by 

finer grained units (Hackley and Ewing, 2010; Hackley, 2012). The upper Claiborne unit is referred to as 

the Yegua Formation in Texas and the Cockfield Formation in Louisiana and Mississippi. The Yegua and 

Cockfield Formations are underlain by the relatively fine-grained Cook Mountain Formation and are 

overlain by the fine-grained Moodys Branch Formation and equivalents within the Jackson Group 

(Lawless and others, 1997; Galloway, 2008; Hackley and Ewing, 2010; Hackley, 2012). Proprietary wellpenetration data (IHS Energy Group, 2011) indicate that the Moodys Branch Formation is restricted to 

east Texas, Louisiana, and Mississippi. Subsurface stratigraphic correlations by Galloway and others 

(1994) support a regionally extensive interpretation of the Moodys Branch Formation and temporally 

equivalent fine-grained strata (Galloway and others, 2000). The Moodys Branch Formation and the 

overlying fine-grained facies of the Jackson Group form the sealing units for the underlying Yegua and 

Cockfield Formations (Hackley, 2012). The succession from the Yegua and Cockfield Formations into the

overlying fine-grained units have been interpreted to represent a landward retreat of depositional 

environments from predominantly coarse-grained, nonmarine fluvial, shallow-marine deltaic, and 

continental-shelf systems (Yegua and Cockfield Formations) to a finer grained, fully marine system 

(Moodys Branch Formation) in the Paleogene Gulf of Mexico (Fisher, 1969; Galloway and others, 2000; 

Galloway, 2008; Hackley, 2012). The overlying Jackson Group has been interpreted to represent an 

extensive, mud-rich shelf system in the central Gulf of Mexico and into the Mississippi Embayment 

(Galloway and others, 2000; Hackley and Ewing, 2010; Hackley, 2012).

The Yegua and Cockfield Formations SAU C50470122 SAU is a potential reservoir unit for CO2

storage in the U.S. Gulf Coast at depths from 3,000 to 11,000 ft (fig. 17). The SAU boundary is defined 

by the 3,000-ft drilling depth from nearly 10,000 well penetrations (IHS Energy Group, 2011) and the 

middle and upper Eocene Yegua shelf edge and associated extent of shallow-marine sandstone (Galloway 

and others, 2000; Galloway, 2005, 2008; see also Hackley, 2012). The range of total storage formation 

thickness for the reservoir unit was determined by tops-differencing from nearly 1,000 well penetrations 

of the top of the Yegua and Cockfield Formations to the top of the Cook Mountain Formation (IHS 

Energy Group, 2011), as well as by review of regional studies of the Yegua Formation (Davies and 

Ethridge, 1971; Galloway and others, 1994; Hackley, 2012). The thickness of the net-porous interval was 

determined from a net-sandstone thickness map by Fisher (1969; see also Hackley, 2012). Average 

porosity ranges from 10 to 40 percent, and average permeability ranges from 0.1 to greater than 3,000 mD 

(Nehring, 1991; Nehring Associates, Inc., 2010). Reservoir data provided by Nehring Associates, Inc. 

(2010) indicates that Yegua Formation reservoirs have a median porosity of 30 percent and a median 

permeability of 175 mD.

Water-quality measurements indicate that groundwater in the Yegua and Cockfield Formations is 

predominantly saline (>10,000 mg/L TDS) (Pettijohn and others, 1988; Breit, 2002). The minimum and 

central tendency buoyant-trapping pore volumes were determined using methods described in Brennan 

and others (2010). Maximum buoyant-trapping pore volume was calculated from the product of (1) the 

combined areas of Yegua and Cockfield structural reservoir traps and reservoirs of producing fields 
51

(Nehring Associates, Inc., 2010), (2) the maximum net-porous-interval thickness, and (3) the maximum 

porosity. Yegua and Cockfield structural reservoir traps include rollover anticlines downthrown to growth 

faults and broad stratal upwarping over areas influenced by salt tectonics (Nicot and Havorka, 2009; 

Hackley, 2012). Combined structural-stratigraphic traps against salt diapirs were not considered as a 

result of limited subsurface data to illustrate closure geometry.
52

Figure 17. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Yegua and Cockfield Formations SAU in the U.S. Gulf 

Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the 

reservoir formation top.
53

Frio and Vicksburg Formations SAU C50470122

By William H. Craddock

The Frio and Vicksburg Formations (fig. 2D) are a southeast-dipping package of siliciclastic 

sediment that was deposited along the Gulf of Mexico continental margin during the Oligocene Epoch 

(Galloway and others, 2000). Four primary depocenters were involved in deposition of the Vicksburg

through Frio stratigraphic package. From the west to east along the continental margin, these are the 

Norias delta, the Norma delta, the Houston delta, and the Mississippi delta (see Galloway and others, 

2000). Vicksburg through Frio strata were deposited in a wide variety of depositional environments, 

including distributary channel, delta plain, delta, interdeltaic embayment, and continental shelf (Galloway 

and others, 1982; Combes, 1993; Galloway and others, 2000). The largest single sediment source was the 

Norias-Norma system, and deltas associated with this system are characterized by wave dominated 

environments. To the east, the Houston and Mississippi systems are characterized by fluvially dominated 

deltas (Galloway and others, 2000). During deposition of the Vicksburg through Frio interval, 

sedimentary systems originating in the western portion of the basin, and eventually those originating in 

the east-central portion of the basin, prograded across the Gulf of Mexico continental shelf and onto the 

continental slope. High sediment fluxes and rapid progradation of depositional systems in the western part 

of the basin are thought to relate to erosion of sediment source areas in northeastern Mexico and the 

southwestern United States (Yurewicz and others, 1997). Progradation of depositional systems across the 

continental shelf in the early Oligocene was followed by sustained systems tract retreat during the late 

Oligocene (Galloway and others, 2000). The retrogradational systems tract that overlies the Vicksburg

and Frio Formations is known regionally as the Anahuac Formation, which typically comprises finegrained, open-marine deposits (Galloway and others, 2000). Regionally, the Anahuac Formation is several 

hundreds of feet thick, perhaps approaching 1,000 ft in some locations, such that it should form a robust 

top-seal for prospective CO2 storage in a Vicksburg-Frio reservoir (Williamson, 1959; Stoudt and others, 

1990; Galloway and others, 1994).

The perimeter of the Frio and Vicksburg Formations SAU C50470122 is defined by several 

geologic and political boundaries, including the 3,000- and 13,000-ft overburden contours, the updip limit 

of fine-grained Anahuac strata that define the regional top-seal, the downdip limit of coarse-grained 

Vicksburg through Frio strata that form the reservoir interval, the U.S.-Mexico international border, and 

State-water boundaries (fig. 18; see Brennan and others, 2010). Overburden contours were generated 

using a database of stratigraphic information from boreholes around the region (IHS Energy Group, 

2011). The 3,000- and 13,000-ft contours define parts of the updip and downdip SAU boundaries, 

respectively. The areal distribution of laterally continuous, shale-prone Anahuac deposits is difficult to 

define at the spatial scale of the entire U.S. Gulf Coast. In order to approximate this, we used a shoreline 

reconstruction for the late Oligocene marine transgression that corresponds to the deposition of the 

Anahuac Formation (Rainwater, 1964). Comparison of the position of the Anahuac shoreline (Rainwater, 

1964) and several regional cross sections that extend across the Texas and Louisiana coastal plain (Stoudt 

and others, 1990; Galloway and others, 1994) suggest that the shorelines are often reasonably good 

indicators of the updip limit of laterally continuous, fine-grained, marine strata. The updip seal boundary 

is subject to an estimated approximately 20 miles of uncertainty, at most. Notably, the updip shale limit 

shifts toward the northern basin margin in the eastern Gulf Coast reflecting the fact that coarse-grained 

sediment flux into the Mississippi embayment was relatively low compared to the Norias-Norma system 

to the west (Rainwater, 1964; Galloway and others, 2000). Because of this pattern, the updip SAU limit is 
54

defined by the 3,000-ft overburden contour in the eastern part of the basin and the top-seal limit in the 

western part of the basin. We define a downdip limit of Vicksburg through Frio sand/sandstone, which 

corresponds to the position of the ultimate Oligocene shelf margin (Galloway and others, 2000). In 

addition to the ultimate Oligocene continental shelf margin, the downdip SAU limit is also partially 

defined by the 13,000-ft overburden contour and the State-waters boundary. The eastern limit of the SAU 

is defined by the gradual transition between siliciclastic rocks in Louisiana and Oligocene carbonates in 

the Florida panhandle region (Galloway and others, 2000). The southwestern limit of the SAU is defined 

by the international border between Texas and Mexico. The SAU has a total area of 23,653,000 acres 

(±10 percent).

The gross thickness of the Vicksburg through Frio stratigraphic package was determined by 

contouring stratigraphic thickness measurements from borehole stratigraphy (IHS Energy Group, 2011). 

Averaged across the basin, gross thickness appears to be between 2,700 and 1,100 ft. Generally, gross 

thickness increases in the basinward direction (see Stoudt and others, 1990) and is relatively large, 

approaching 7,000 ft, at major sediment outlets, such as the Norias-Norma delta and the Houston delta. In 

between these deltas, the formations thin to about 1,000 to 3,000 ft of net-sandstone thickness. Net 

thickness was determined from a variety of data sources, including net-sandstone isolith maps (Bebout 

and others, 1975; Bebout and others, 1976) and net-to-gross factors that were applied to the grossthickness isopach map (Burke, 1958; IHS Energy Group, 2011). The highest net-sandstone thicknesses 

are associated with the Norias-Norma delta systems, where net thickness may be in excess of 3,000 ft. Net 

Oligocene-sandstone thicknesses generally decrease to the east and basinward, and near the downdip edge 

of the SAU in Louisiana and eastern Texas, there may be very little (perhaps tens of feet) net sandstone. 

At a regional scale, the net thickness of porous reservoir rock is on the order of 900 ± 600 ft. 

In order to characterize the porosity and permeability of the Vicksburg and Frio Formations at the 

scale of the entire U.S. Gulf Coast, petroleum-reservoir-averaged porosity measurements were plotted 

against reservoir depth for Paleogene sandstone reservoirs on the Gulf of Mexico coastal plain (Nehring 

Associates, Inc., 2010). The plot contains 1,358 petroleum-reservoir-averaged porosity measurements 

(Nehring Associates, Inc., 2010), and it suggests that within the SAU depth range, average reservoir 

porosity is 22 ± 4 percent. This number is in reasonable agreement with other studies of Frio sandstone 

porosity from various swaths of the Texas coastal plain (Maxwell, 1964; Loucks and others, 1979; 

Galloway and others, 1982). A similar dataset of 1,035 petroleum-reservoir-averaged permeability 

measurements was compiled for Paleogene sandstones of the Gulf coastal plain (Nehring Associates, Inc., 

2010). This dataset suggests that the permeability of the Frio Formation ranges from 0.1 to 3,000 mD, 

with a most-likely value of approximately 200 mD. 

Regional analysis of the salinity of formation waters for various Tertiary formations of the Gulf of 

Mexico coastal plain shows that salinity within the SAU increases with increasing burial depth, as well as 

down the depositional dip of the basin (Pettijohn and others, 1988). The Frio and Vicksburg Formations 

SAU is located entirely downdip of the area that contains formation waters with TDS concentrations 

<10,000 mg/L, such that the viable storage area does not appear to be significantly limited by the presence 

of potable formation waters. 

In order to approximate the maximum volume that is available for storing CO2 in buoyant traps (see 

Brennan and others, 2010), the area of structural and (or) stratigraphic enclosures was combined with the 

most-likely values for net-sandstone thickness and porosity. The vast majority of traps within this interval 

appear to be either structural or combination structural-stratigraphic traps (Nehring Associates, Inc., 

2010), such that it may be reasonable to combine the enclosed area with the entire net sandstone 

thickness. The area of enclosed pore volume was approximated by combining the number of petroleum 

fields with an estimate of a most-common reservoir size (Nehring Associates, Inc., 2010).
55

Figure 18. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Frio and Vicksburg Formations SAU in the U.S. Gulf 

Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the 

reservoir formation top.
56

Lower Miocene I SAU C50470123, Lower Miocene II SAU C50470124, Middle 

Miocene SAU C50470125, and Upper Miocene SAU C50470126

By William H. Craddock

Miocene strata (fig. 2E) deposited along the Gulf of Mexico continental margin dip gently to the 

southeast and expand in the basinward direction. Five primary depocenters were involved in deposition of 

the Miocene strata. From west to east, these include the Norma delta, the North Padre delta, the Corsair 

delta, the Calcasieu delta, and the Mississippi delta (Galloway and others, 2000). The strata were 

deposited in a wide variety of depositional settings, including distributary channel, delta plain, delta, 

interdeltaic embayment, continental shelf, and upper continental slope (Galloway and others, 2000). A 

detailed review of the Miocene depositional history is beyond the scope of this report, and readers are 

referred to a recent review by Galloway and others (2000) for additional details. However, some key 

geologic observations relating to this stratigraphic package are highlighted herein. Firstly, relative to the

Oligocene, sediment influx into the western portion of the basin tapered, whereas sediment influx into the 

eastern portion of the basin (particularly the Mississippi River axes) accelerated (Galloway and others, 

2000). Generally speaking, progradation of the continental shelf across the south Texas continental 

margin was modest, approximately a few tens of miles over the course of the Miocene. In contrast, the 

Louisiana continental shelf margin prograded basinward by more than 100 miles. To the east of 

Louisiana, the continental shelf was largely sediment starved in the early Miocene, but sediment supply 

accelerated during the middle and late Miocene causing deltaic systems to advance rapidly to the 

continental shelf margin over spatial scales similar to the central Mississippi axis (Galloway and others, 

2000). Secondly, fluctuations in eustatic sea level during the Miocene exerted a first-order influence on 

the evolving paleogeography of the region (Galloway and others, 2000; Miller and others, 2005). We 

defined four retrogradational packages deposited during major transgressions, and they serve as finegrained regional sealing units and subdivide the Miocene section into four SAUs (adapted from Galloway 

and others, 2000): Lower Miocene I SAU C50470123, Lower Miocene II SAU C50470124; Middle 

Miocene SAU C50470125, and Upper Miocene SAU C50470126 (figs. 19 to 22). 

The perimeter of the various Miocene SAUs is defined by several parameters, which include

3,000- and 13,000-ft overburden contours, the updip limit of shale-prone strata in the sealing units, the 

downdip limit of continental shelf deposits, the U.S.-Mexico international border, and State-water 

boundaries (figs. 19 to 22; see Brennan and others, 2010). Overburden contours were adapted from a 

recent USGS undiscovered oil and gas assessment of the Miocene strata of the Gulf coastal plain, and the 

3,000- and 13,000-ft contours define parts of the updip and downdip SAU boundaries, respectively (R. 

Dubiel, USGS, written commun., 2011). The landward limit of the shale-prone packages that separate the 

Miocene stratigraphic packages were adapted from a reconstruction of Oligocene and Miocene shorelines 

during major marine transgressions in the Oligocene and Miocene (Rainwater, 1964). Comparison of the 

position of these shorelines with regional cross sections (Doyle, 1979; Stoudt and others, 1990) suggests 

that the shorelines accurately define the updip limit of homogeneous, fine-grained strata. Additionally, 

these shale-prone stratigraphic intervals should act as robust regional seals. The updip seal boundary is 

estimated to have about 20 miles of uncertainty, at most. Paleogeographic reconstructions of ultimate 

continental shelf edges during the various Miocene progradational events were used to define the 

basinward limit of sandstone reservoir rock because it was assumed that a transition from relatively 

coarse-grained to fine-grained rocks occurs along the continental shelf-slope boundary (Galloway and 

others, 2000). The Lower Miocene SAU boundaries are generally defined by top-seal limits along their 
57

updip edges and State-water boundaries and (or) 13,000-ft overburden contours along their downdip 

edges. The Middle and Upper Miocene SAUs are defined almost entirely by the updip top-seal limit and 

the State-water boundaries. Due to the fact that the top-seal limits nearly overlap the Texas State-waters 

boundary for the Middle and Upper Miocene SAUs, the majority of the area of these SAUs is situated 

along the Louisiana coast, and narrow, disconnected sections of the SAUs extend along the Texas Statewaters boundary. In stratigraphic order (older to younger), these SAUs cover areas of 8,432,000 acres, 

9,924,000 acres, 3,619,000 acres, and 1,933,000 acres. We consider the uncertainty on these area 

measurements to be about 10 percent.

A variety of data were aggregated in order to determine the gross thickness of the storage 

reservoirs, as well as the net-sandstone thicknesses within the reservoirs. The data include gross formation 

isopachs and percent-sand contours from a USGS Miocene undiscovered oil and gas assessment (R. 

Dubiel, USGS, written commun., 2011), gross-formation thickness and net-to-gross contours for the 

Texas coastal region (Doyle, 1979), and net-sandstone isolith maps for the southern Texas coastal region 

(Morton and others, 1988). Generally speaking, the highest gross and net thicknesses correspond to the 

major deltaic axes, and the central Mississippi River depocenter is typically much thicker than 

depocenters to the west. Between the major depocenters, gross and net-sandstone thicknesses decrease 

dramatically. For the Lower Miocene I SAU, gross thickness appears to average 1,500 ± 500 ft. 

Maximum thicknesses are associated with the Mississippi delta and may be as much as 8,000 ft near the 

downdip edge of the SAU, although gross thickness of 1,000 ft or more is observed across the Texas 

State-waters region, on average. Net-sandstone thickness appears to average 600 ± 300 ft across this SAU. 

Again, maximum thicknesses are associated with the Mississippi delta, and they may exceed 1,500 ft. 

Along the Corsair delta in Texas, net-sandstone thickness may approach 400 ft. For the Lower Miocene II 

SAU, gross-thickness estimates average 1,600 ± 300 ft, with thicknesses in excess of 6,000 ft in the 

Mississippi delta, thicknesses of thousands of feet in the Corsair delta, and thin zones located away from 

the major depocenters. Net-sandstone thicknesses for this SAU are 550 ± 200 ft. The updip portion of the 

Mississippi delta area may have aggregate sandstone thickness >1,000 ft, whereas the thickest sandstone 

accumulations in Texas, along the Corsair delta, approaches 1,000 ft. An average gross thickness of 3,200 

± 900 ft was estimated for the Middle Miocene SAU, with thicknesses in excess of 6,000 ft at the 

Mississippi delta and thicknesses of hundreds of feet in the narrow swaths of the SAU that are located 

along the Texas State-waters boundary. Net-sandstone thickness estimates are 480 ± 140 ft, with 

thicknesses approaching 1,000 ft in the Mississippi delta and thicknesses of hundreds of feet across 

offshore Texas. Finally, the average gross thickness of the Upper Miocene SAU is estimated to be 5,400 ± 

1,000 ft, with thicknesses in excess of 10,000 ft at the Mississippi delta, and thicknesses in excess of 

1,000 ft at the Norma delta. The average net-sandstone thickness of the Upper Miocene SAU is 1,500 ± 

400 ft, with thicknesses in excess of 3,000 ft at the Mississippi delta and in excess of 1,000 ft at the 

Norma delta.

The Nehring Associates, Inc. (2010) production database was used to characterize the porosity and 

permeability of the Miocene SAUs. From this database of 432 petroleum-reservoir-averaged porosity 

measurements, a basin-wide, sandstone compaction curve for Neogene sandstone reservoirs around the 

Gulf Coast region was generated. The database suggests relatively high porosities at any given burial 

depth in comparison to underlying Paleogene strata. Given that the distribution of burial depths is 

relatively even across the region, a mean burial depth of 8,000 ft was assumed for all SAUs to estimate 

regional porosity directly from the Neogene compaction curve. Within the SAUs, regional reservoir 

porosity appears to be approximately 28 ± 4 percent. Permeability was estimated from 259 petroleum 

reservoirs on the coastal plain. Similar to porosity, regional permeability appears to be high, with a mostlikely value of about 500 mD (Nehring Associates, Inc., 2010). Similar to other geologic formations, 

permeability varies over a wide range, and individual petroleum reservoirs may exhibit permeability as 

low as 20 mD and as high as 8,000 mD.
58

Regional analysis of the salinity of formation waters for various Tertiary formations of the Gulf 

coastal plain has shown that salinity tends to increase with increasing burial depth, as well as down the 

depositional dip of the basin (Pettijohn and others, 1988). In general, the Miocene SAUs are located in 

zones of high salinity, with TDS values well in excess of 10,000 mg/L. The highest potential for 

groundwater accumulations with TDS <10,000 mg/L in any of the Miocene SAUs appears to be within 

the far eastern margin of the Lower Miocene II SAU (Pettijohn and others, 1988), although this 

potentially saline area appears to encompass no more than 10 percent of the SAU area.

In order to approximate the maximum volume that is available for storing CO2 in buoyant traps (see 

Brennan and others, 2010), the area of structural and (or) stratigraphic enclosures was combined with the 

probable net-sandstone thickness and porosity of the various Miocene stratigraphic intervals. The 

approach to this calculation is identical to the approach used for the Frio and Vicksburg Formations SAU.
59

Figure 19. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Lower Miocene I SAU in the U.S. Gulf Coast. Grid cells 

(one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation 

top.
60

Figure 20. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Lower Miocene II SAU in the U.S. Gulf Coast. Grid cells 

(one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation 

top.
61

Figure 21. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Middle Miocene SAU in the U.S. Gulf Coast. Grid cells 

(one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation 

top.
62

Figure 22. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Upper Miocene SAU in the U.S. Gulf Coast. Grid cells 

(one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the reservoir formation 

top.
63

Tertiary Slope and Basin Floor SAU C50470127

By Matthew D. Merrill, William H. Craddock, and Tina L. Roberts-Ashby

The Tertiary Slope and Basin Floor SAU C50470127 is a nonquantitative SAU that includes 

continental-slope and basin-floor deposits, situated downdip of the ultimate continental shelf margins for 

the various Tertiary depositional episodes in the Gulf Coast region (Ewing and Lopez, 1991; Galloway 

and others, 2000). Since continental slope deposits tend to be muddy and lack good reservoir quality, the 

best opportunity for reservoir rock in the Tertiary Slope and Basin Floor SAU C50470127 is probably in 

submarine canyon and upper slope channel-fill deposits, which tend to be coarse grained, thereby 

enhancing the potential for increased storage reservoir quality. Additionally, these channel fills tend to be 

located closer to the base of the continental slope or local salt diaper bathymetry inversions, such that 

there is potentially a better chance for reservoir rock in relatively downdip regions, as updip of the 

continental slope, canyon channel-fills are generally sites of erosion and (or) bypass. Additionally, basinfloor fans and wide basin-floor aprons could act as potential storage reservoirs for CO2 sequestration 

within this SAU. The Tertiary Slope and Basin Floor SAU C50470127 is hypothetically composed of the 

lower Tertiary Wilcox Group and Carrizo Sand through the Miocene-age sands (fig. 2E) at depths greater 

than 13,000 ft below the surface. For further information on the lithology and depositional environments 

of the stratigraphic units that comprise this SAU, see descriptions for SAUs C50470118 through 

C50470126 of this report. The regional seal that potentially overlies this SAU is poorly understood; 

however, it is assumed to be fine, terrestrial, basin-floor deposits of Tertiary age.

The Tertiary Slope and Basin Floor SAU C50470127 has an area of around 28,949,000 acres (fig. 

23). The boundaries of the SAU extend from the Upper Cretaceous Stuart City reef margin in the north, a 

boundary that also coincides with the southern or downdip limit of the Carrizo Sand and Wilcox Group

SAU C50470118, to the downdip direction and up to the State-waters boundary off the coasts of Texas 

and Louisiana. The western limit of the SAU is the U.S.-Mexico international border, and the eastern 

boundary is marked by the Federal-State-waters boundary in the Mississippi delta region of Louisiana. 

Based upon water-quality data (Breit, 2002) and regional groundwater studies (Pettijohn and 

others, 1988), the SAU is thought to contain exclusively saline waters (TDS >10,000 mg/L). Although the 

Tertiary Slope and Basin Floor SAU C50470127 probably has significant potential to serve as a CO2

storage reservoir, data availability for all of the reservoir units within the SAU, as well as data needed to 

characterize the seal, are limited; therefore, the Tertiary Slope and Basin Floor SAU C50470127 is a 

nonquantitatively assessed SAU.
64

Figure 23. Map of the U.S. Geological Survey storage assessment unit (SAU) boundary for the Tertiary Slope and Basin Floor SAU in the U.S. Gulf 

Coast. Grid cells (one square mile) represent counts of wells derived from ENERDEQ well database (IHS Energy Group, 2011) that have penetrated the 

reservoir formation top.
65

Acknowledgments

The authors thank Paul G. Schuben and Brian Verela, who helped to compile and process the 

drilling and hydrocarbon production data for the region, and Troy A. Cook, Mahendra K. Verma, and 

Hossein Jahediesfanjani, who helped to interpret the petroleum engineering data. The authors also thank 

the Southeast Regional Carbon Sequestration Partnership; the Texas Bureau of Economic Geology, 

University of Texas at Austin; the Louisiana Geological Survey; the Office of Land and Water Resources, 

Mississippi Department of Environmental Quality; the Geological Survey of Alabama; and the Florida 

Geological Survey for their help in supplying geologic information for their respective State used in this 

assessment. The content and presentation of this report benefited greatly from the technical reviews of

James Coleman and Sharon Swanson.

References Cited

Aconcha E.S., 2008, Integrating core, well logs, and seismic interpretation to improve understanding of 

Albian patch reefs, Maverick Basin, SW Texas, American Association of Petroleum Geologists Annual 

Convention and Exhibition, San Antonio, Tex., April 20‒23, 2008, Proceedings: San Antonio, Tex., 

American Association of Petroleum Geologists, Search and Discovery Article #50104, 34 p.

Adams, G.I., 1928, The course of the Tennessee River and the physiography of the southern Appalachian 

region: Journal of Geology, v. 36, p. 481‒493.

Ahr, W.M., 1981, The Gilmer Limestone—Oolite tidal bars on the Sabine uplift: Gulf Coast Association 

of Geological Societies Transactions, v. 31, p. 1‒6.

Badon, C.L., 1975, Stratigraphy and petrology of Jurassic Norphlet Formation, Clarke County, 

Mississippi: American Association of Petroleum Geologists Bulletin, v. 59, no. 3, p. 377‒392.

Barnes, V.E., 1967a, Geologic atlas of Texas, Lubbock Sheet, Halbert Pleasant Bybee memorial edition: 

University of Texas at Austin, Bureau of Economic Geology, 1 sheet, scale 1:250,000.

Barnes, V.E., 1967b, Geologic atlas of Texas, Sherman Sheet, Walter Scott Adkins memorial edition: 

University of Texas at Austin, Bureau of Economic Geology, 1 sheet, scale 1:250,000.

Barnes, V.E., 1972, Geologic atlas of Texas, Dallas Sheet, Gayle Scott memorial edition: University of 

Texas at Austin, Bureau of Economic Geology, 1 sheet, scale 1:250,000.

Bearden, B.L., Mancini, E.A., and Puckett, T.M., 2000, Salt anticline play in the Mississippi Interior Salt 

Basin: Gulf Coast Association of Geological Societies Transactions, v. 50, p. 261‒268.

Bebout, D.G., and Loucks, R.G., 1974, Stuart City trend, Lower Cretaceous, South Texas—A carbonate 

shelf-margin model for hydrocarbon exploration: University of Texas at Austin, Bureau of Economic 

Geology Report of Investigations 78, 80 p.

Bebout, D.G., Agagu, O.K., and Dorfman, M.H., 1975, Geothermal resources Frio Formation, middle 

Texas Gulf Coast: University of Texas at Austin, Bureau of Economic Geology, Geological Circular,

no. 75-8, 43 p.

Bebout, D.G., Loucks, R.G., Bosch, S.C., and Dorfman, M.H., 1976, Geothermal resources Frio 

Formation, upper Texas Gulf Coast: University of Texas at Austin, Bureau of Economic Geology, 

no. 76-3, 47 p.

Bebout, D.G., White, W.A., Garrett, C.M., Jr., and Hentz, T.F., eds., 1992, Atlas of major central and 

eastern Gulf Coast gas reservoirs: University of Texas at Austin, Bureau of Economic Geology, 88 p.

Berg, O.R., 1982, Seismic detection and evaluation of delta and turbidite sequences—Their application to 

exploration for the subtle trap: American Association of Petroleum Geologists Bulletin, v. 66, 

p. 1271‒1288.

Blondes, M., Brennan, S., Merrill, M., Buursink, M., Attanasi, E., Warwick, P., Cahan, S., Corum, M., 

Cook, T., Craddock, W., DeVera, C., Drake, R., Drew, L., Freeman, P., Lohr, C., Olea, R., Roberts-
66

Ashby, T., Slucher, E., and Varela, B., 2013, National assessment of geologic carbon dioxide storage 

resources—Methodology implementation: U.S. Geological Survey Open-File Report 2013‒1055, 26 p., 

http://pubs.usgs.gov/of/2013/1055/.

Bolin, D.E., Mann, S.D., Burroughs, D., Moore, H.E., Jr., and Powers, T.J., 1989, Petroleum atlas of 

southwestern Alabama: Geological Survey of Alabama Atlas, v. 23, 218 p. 

Branson, D.O., 1950, Blackfoot field, Anderson County, Texas: American Association of Petroleum 

Geologists Bulletin, v. 34, no. 8, p. 1750‒1755.

Breit, G.N., 2002, Produced waters database: U.S. Geological Survey online database, accessed on March 

23, 2011, at http://energy.cr.usgs.gov/prov/prodwat/.

Brennan, S.T., Burruss, R.C., Merrill, M.D., Freeman, P.A., and Ruppert, L.F., 2010, A probabilistic 

assessment methodology for the evaluation of geologic carbon dioxide storage: U.S. Geological Survey 

Open-File Report 2010–1127, 31 p., http://pubs.usgs.gov/of/2010/1127/ofr2010-1127.pdf.

Brown, T.E., 1971, Stratigraphy of the Washita Group in central Texas: Baylor University, Waco, Tex., 

Baylor Geological Studies Bulletin No. 21, 41 p.

Burke, R.A., 1958, Summary of oil occurrence in Anahuac and Frio Formations of Texas and Louisiana, 

American Association of Petroleum Geologists Bulletin, v. 42, no. 12, p. 2935–2950.

Burruss, R.C., Brennan, S.T., Freeman, P.A., Merrill, M.D., Ruppert, L.F., Becker, M.F., Herkelrath, 

W.N., Kharaka, Y.K., Neuzil, C.E., Swanson, S.M., Cook, T.A., Klett, T.R., Nelson, P.H., and Schenk, 

C.J., 2009, Development of a probabilistic assessment methodology for evaluation of carbon dioxide 

storage: U.S. Geological Survey Open-File Report 2009–1035, 81 p., 

http://pubs.usgs.gov/of/2009/1035/ofr2009-1035.pdf. 

Byram, K.G., 1988, Petrographic analysis of the Gilmer Limestone, Louark Group (Upper Jurassic), Box 

Church field, Limestone County, Texas: Austin, Tex., Austin State University, M.S. thesis, 150 p.

Cagle, J.W., and Khan, M.A., 1983, Smackover-Norphlet stratigraphy, South Wiggins arch, Mississippi 

and Alabama: Gulf Coast Association of Geological Societies Transactions, v. 33, p. 23‒29.

Cicero, A.D., Steinhoff, I., McClain, T., Koepke, K.A., and Dezelle, J.D., 2010, Sequence stratigraphy of 

the Upper Jurassic mixed carbonate/siliciclastic Haynesville and Bossier Shale depositional systems in 

east Texas and north Louisiana: Gulf Coast Association of Geological Societies Transactions, v. 60, 

p. 133‒148.

Clark, W.J., 1995, Depositional environments, diagenesis, and porosity of Upper Cretaceous volcanic-rich 

Tokio Sandstone reservoirs, Haynesville field, Claiborne Parish Louisiana: Gulf Coast Association of 

Geological Societies Transactions, v. 45, p. 127‒134.

Coleman, J.L., Jr., and Coleman, C.J., 1981, Stratigraphic, sedimentologic, and diagenetic framework for 

the Jurassic Cotton Valley Terryville massive sandstone complex, northern Louisiana: Gulf Coast 

Association of Geological Societies Transactions, v. 31, p. 71‒79.

Collins, K.M., 2008, Petrography of the Cook-McCormick core, Eutaw Formation, Heidelberg field 

Mississippi and relationship to microbial permeability profile modification: Starkville, Mississippi 

State, M.S. thesis, 112 p.

Combes, J.M, 1993, The Vicksburg Formation of Texas, depositional systems distribution, sequence 

stratigraphy and petroleum geology: American Association of Petroleum Geologists Bulletin, v. 77, 

p. 1942–1970.

Condon, S.M., and Dyman, T.S., 2003, Geologic assessment of undiscovered conventional oil and gas 

resources in the Upper Cretaceous Navarro and Taylor Groups, Western Gulf Province, Texas, chap. 2 

of U.S. Geological Survey Western Gulf Province Assessment Team, Petroleum systems and geologic 

assessment of the undiscovered oil and gas, Navarro and Taylor Groups, Western Gulf Province, Texas:

U.S. Geological Survey Digital Data Series 69‒H, 42 p.
67

Cregg, A.K. and Ahr, W.M., 1983, Depositional framework and reservoir potential of an upper Cotton 

Valley (Knowles Limestone) patch reef, Milam County, Texas: Gulf Coast Association of Geological 

Societies Transactions, v. 33, p. 55‒68.

Davies, D.K., and Ethridge, F.G., 1971, The Claiborne Group of central Texas—A record of middle 

Eocene marine and coastal plain deposition: Gulf Coast Association of Geological Societies 

Transactions, v. 21, p. 119‒128.

Dennen, K.O., and Hackley, P.C., 2012, Definition of Greater Gulf Basin Lower Cretaceous Shale Gas 

Assessment Unit, United States Gulf of Mexico Basin onshore and State waters, in American 

Association of Petroleum Geologists Annual Convention and Exhibition, Houston, Tex., April 10‒13, 

2011, Proceedings: Houston, Tex., American Association of Petroleum Geologists, Search and 

Discovery Article #10429, 37 p.

Dingus, W.F., and Galloway, W.E., 1990, Morphology, paleogeographic setting, and origin of the middle 

Wilcox Yoakum Canyon, Texas coastal plain: American Association of Petroleum Geologists Bulletin, 

v. 74, no. 7, p. 1055–1076.

Dixon, S.A., Summers, D.M., and Surdam, R.C., 1989, Diagenesis and preservation of porosity in 

Norphlet Formation (Upper Jurassic), southern Alabama: American Association of Petroleum 

Geologists Bulletin, v. 73, no. 6, p. 707‒728.

Doyle, J.D., 1979, Depositional patterns of Miocene facies, middle Texas coastal plain: University of 

Texas at Austin, Bureau of Economic Geology, Geological Circular, no. 99, 28 p.

Dubiel, R.F., Coleman, J.L., Hackley, P.C., Hayba, D.O., Karlsen, A.W., Pearson, O.N., Pitman, J.K., 

Swanson, S.M., Warwick, P.D., 2007a, Assessment of undiscovered oil and gas resources in Tertiary 

strata of the Gulf Coast, 2007: U.S. Geological Survey Fact Sheet 2007‒3066, 4 p.

Dubiel R.F., Pitman, J.K., Pearson, O.N., Condon, S.M., Warwick, P.D., Karlsen, A.W., Coleman, J.L. 

Hackley, P.C., Hayba, D.O., Swanson, S.M., Charpentier, R.R., Cook, T.A., Klett, T.R., Pollastro, 

R.M., and Schenk, C.J., 2007b, Assessment of undiscovered oil and gas resources in Tertiary strata and 

Cretaceous-Tertiary coalbed gas of the Gulf Coast: U.S. Geological Survey Fact Sheet 2007‒3066, 

4 p.

Dubiel, R.F., Warwick, P.D., Swanson, S.M., Burke, L.A., Biewick, L.R.H., Charpentier, R.R., Coleman, 

J.L., Cook, T.A., Dennen, K., Doolan, C., Enomoto, C.B., Hackley, P.C., Karlsen, A.W., Klett, T.R., 

Kinney, S.A., Lewan, M.D., Merrill, M.D., Pearson, K.M., Pearson, O.N., Pitman, J.K., Pollastro, R.M., 

Rowan, E.L., Schenk, C.J., and Valentine, B.J., 2011, Assessment of undiscovered oil and gas resources 

in Jurassic and Cretaceous strata of the Gulf Coast, 2010: U.S. Geological Survey Fact Sheet 2011‒

3020, 4 p.

Dubiel, R.F., Pitman, J.K., Pearson, O.N., Pearson, K.M., Kinney, S.A., Lewan, M.D., Burke, L.A., 

Biewick, L.R.H., Charpentier, R.R., Cook, T.A., Klett, T.R., Pollastro, R.M., and Schenk, C.J., 2012, 

Assessment of undiscovered oil and gas resources in conventional and continuous petroleum systems in 

the Upper Cretaceous Eagle Ford Group, U.S. Gulf Coast region, 2011: U.S. Geological Survey Fact 

Sheet 2012–3003, 2 p.

Dubroff, D.D., 1987, Iola, South (Sub-Clarksville) field, Grimes and Brazos Counties, Texas, in Typical 

oil and gas fields of southeast Texas, v. 2: Houston Geological Society, p. 303‒309.

Dyer, M.J., and Bartolini, C., 2004, Sabinas Basin Lower Cretaceous to Jurassic production—Comparison 

to south Texas equivalents: Gulf Coast Association of Geological Societies Transactions, v. 54, 

p. 169‒184.

Dyman, T.S., and Condon, S.M., 2006, Assessment of undiscovered conventional oil and gas resources—

Lower Cretaceous Travis Peak and Hosston Formations, Jurassic Smackover Interior Salt Basins Total 

Petroleum System, in the East Texas Basin and the Louisiana-Mississippi Salt Basins provinces, chap. 5 

of Petroleum systems and geologic assessment of undiscovered oil and gas, Cotton Valley

Group and Travis Peak–Hosston Formations, East Texas Basin and Louisiana-Mississippi
68

Salt Basins Provinces of the northern Gulf Coast region: U.S. Geological Survey Digital Data Series 69‒

E, 39 p.

Echols, J.B., and Goddard, D.A., 1992, Sea level fluctuations, Paleocene middle Wilcox stratigraphy and 

hydrocarbon distribution in east-central Louisiana: Gulf Coast Association of Geological Societies, 

Transactions, v. 42, p. 459–466.

Ehrenberg, S.N., Nadeau, P.H., and Steen, Ø, 2009, Petroleum reservoir porosity versus depth—Influence 

of geological age: American Association of Petroleum Geologists Bulletin, v. 93, no. 10, p. 1281‒1296.

Esposito, R.A., Pashin, J.C., and Walsh, P.M., 2008, Citronelle dome—A giant opportunity for multizone 

carbon storage and enhanced oil recovery in the Mississippi Interior Salt Basin of Alabama: American 

Association of Petroleum Geologists Environmental Geosciences, v. 15 , no. 2, p. 53‒62.

Ewing, T.E., 2001, Review of Late Jurassic depositional systems and potential hydrocarbon plays, 

northern Gulf of Mexico Basin: Gulf Coast Association of Geological Societies Transactions, v. LI, 

p. 85‒96.

Ewing, T.E., 2009a, Southwest Texas heavy oil province: South Texas Geological Society Bulletin, v. 50. 

no. 4, p. 17‒34.

Ewing, T.E., 2009b, The ups and downs of the Sabine uplift and the northern Gulf of Mexico Basin—

Jurassic basement blocks, Cretaceous thermal uplifts, and Cenozoic flexures: Gulf Coast Association of 

Geological Societies Transactions, v. 59, p. 253‒269.

Ewing, T.E., and Caran, S.C., 1982, Late Cretaceous volcanism in south and central Texas—

Stratigraphic, structural, and seismic models: Gulf Coast Association of Geological Societies 

Transactions, v. 32, p. 137‒145.

Ewing, T.E., and Lopez, R.F., 1991, Principal structural features, Gulf of Mexico Basin, in Salvador, A., 

ed., The geology of North America—The Gulf of Mexico Basin: Geological Society of America, v. J, 

plate 2, 1 sheet.

Fergus, P., 1935, Monroe gas field, Louisiana, in Ley, H.A., ed., Geology of natural gas: American 

Association of Petroleum Geologists Special Publication 7, p. 741–772.

Fillon, R.H., Lawless, P.N., and Lytton, R.G., III, 1998, Chronostratigraphy of the expanded lower 

Paleogene wedge in southern Louisiana—An identity crisis for the Wilcox: Gulf Coast Association of 

Geological Societies, Transactions, v. 48, p. 53–66.

Fisher, W.L., 1969, Facies characterization of Gulf Coast delta systems, with some Holocene analogues:

Gulf Coast Association of Geological Societies Transactions, v. 19, p. 239‒261.

Fisher, W.L., and McGowen, J.H., 1969, Depositional systems in Wilcox Group (Eocene) of Texas and 

their relation to occurrence of oil and gas: American Association of Petroleum Geologists Bulletin, 

v. 53, no. 1, p. 30‒54.

Fishman, N.S., Turner, C.E., Peterson, Fred, Dyman, T.S., and Cook, Troy, 2008, Geologic controls on 

the growth of petroleum reserves: U.S. Geological Survey Bulletin 2172–I, 53 p.

Forgotson, J.M., Jr., 1963, Depositional history and paleotectonic framework of Comanchean Cretaceous 

Trinity Stage, Gulf Coast area: American Association of Petroleum Geologists Bulletin, v. 47, no. 1 

p. 69‒103.

Forgotson, J.M. and Forgotson, Jr., J.M., 1976, Definition of Gilmer Limestone, Upper Jurassic 

Formation, northeastern Texas: American Association of Petroleum Geologists Bulletin, v. 60, no. 7, 

p. 1119‒1123.

Fowler, H.E., and Benson, D.J., 2000, Characterization of the Smackover Reservoir—Chatom field, 

Washington County, Alabama, American Association of Petroleum Geologists/EAGE International 

Research Conference, El Paso, Texas: American Association of Petroleum Geologists Search and 

Discovery Article #90049, p. 27.
69

Fox, W.J., and Hopkins, O.N., Jr., 1960, The Georgetown Limestone, in Baylor Geological Society, ed., 

Cretaceous stratigraphy of the Grand and Black Prairies, east-central Texas: Baylor Geological Society 

Field Conference Guidebook No. 5, p. 88‒94.

Freeman, V.L., 1964, Geologic map of the Indian Wells quadrangle, Terrell and Brewster Counties, 

Texas: U.S. Geological Survey Miscellaneous Investigations Series Map I-395, 1 sheet, scale 1:62,500.

Galloway, W.E., 1968, Depositional systems of the lower Wilcox Group, north-central Gulf Coast Basin: 

Gulf Coast Association of Geological Societies, Transactions, v. 28, p. 275‒289.

Galloway, W.E., 2005, Gulf of Mexico Basin depositional record of Cenozoic North American drainage 

basin evolution: Special Publication of the International Association of Sedimentologists No. 35, 

p. 409‒423.

Galloway, W.E., 2008, Depositional evolution of the Gulf of Mexico sedimentary basin, in Miall, A.D., 

ed., The sedimentary basins of the United States and Canada: Amsterdam, The Netherlands, Elsevier, 

p. 505‒549.

Galloway, W.E., 2011, Pre-Holocene geological evolution of the northern Gulf of Mexico Basin, in Gulf 

of Mexico origin, waters, and biota: College Station, Texas A&M University Press, p. 33‒52. 

Galloway, W.E., Hobday, D.K., and Magara, K., 1982, Frio Formation of Texas Gulf Coastal Plain –

Depositional systems, structural framework, and hydrocarbon distribution: American Association of 

Petroleum Geologists Bulletin, v. 66, no. 6, p. 640‒688.

Galloway, W.E., Ewing, T.E., Garrett, C.M., Tyler, Noel, and Bebout, D.G., 1983, Atlas of major Texas 

oil reservoirs: University of Texas at Austin, Bureau of Economic Geology Atlas AT0002, 139 p.

Galloway, W.E., Bebout, D.G., Fisher, W.L., Dunlap, J.B., Jr., Cabrera-Castro, R., Lugo-Rivera, J.E., and 

Scott, T.M., 1991, Cenozoic, in Salvador, A., ed., The geology of North America—The Gulf of Mexico 

Basin: Geological Society of America, v. J, p. 245‒324.

Galloway, W.E., Liu, X., Travis-Neuberger, D., and Xue, L., 1994, Reference high-resolution correlation 

cross sections, Paleogene section, Texas coastal plain: Bureau of Economic Geology CS0010, 19 p., 5 

high-resolution correlation cross sections.

Galloway, W.E., Ganey-Curry, P.E., Li, X., and Buffler, R.T., 2000, Cenozoic depositional history of the 

Gulf of Mexico Basin: American Association of Petroleum Geologists Bulletin, v. 84, p. 1743–1774.

George, P.G., Mace, R.E., Petrossian, R., 2011, Aquifers of Texas: Texas Water Development Board, 

Report 380, 172 p., 

http://www.twdb.state.tx.us/publications/reports/numbered_reports/doc/R380_AquifersofTexas.pdf.

Goldhammer, R.K., and Johnson, C.A., 2001, Middle Jurassic‒Upper Cretaceous paleogeographic 

evolution and sequence-stratigraphic framework of the northwest Gulf of Mexico rim, in Bartolini, C., 

Buffler, R.T., and Cantú-Chapa, A., eds., The western Gulf of Mexico Basin—Tectonics, sedimentary 

basins, and petroleum systems: American Association of Petroleum Geologists Memoir 75, p. 45‒81.

Greer, B.R., 1995, Deposition and remaining productive capabilities of the Upper Cretaceous Eutaw sands 

of east-central Mississippi: Gulf Coast Association of Geological Societies Transactions, v. 45, 

p. 229‒235.

Grubbs, E.L., 1953, Variations in porosity and permeability in the Wilcox Group of the Texas upper Gulf 

Coast, in Carlson, M.B., ed., Gulf Coast Association of Geological Societies, Third Annual Meeting: 

Gulf Coast Association of Geological Societies Transactions, v. 3, p. 54‒70.

Guevara, E., II, and Garcia, R., 1972, Depositional systems and oil-gas reservoirs in the Queen City 

Formation (Eocene), Texas: Gulf Coast Association of Geological Societies, Transactions, v. 22, 

p. 1‒22.

Hackley, P.C., 2012, Geologic assessment of undiscovered conventional oil and gas resources—Middle 

Eocene Claiborne Group, United States part of the Gulf of Mexico Basin: U.S. Geological Survey 

Open-File Report 2012–1144, 87 p.
70

Hackley, P.C., and Ewing, T.E., 2010, Assessment of undiscovered conventional oil and gas resources, 

onshore Claiborne Group, United States part of the northern Gulf of Mexico Basin: American 

Association of Petroleum Geologists Bulletin, v. 94, p. 1607‒1636.

Hamlin, S., 1983, Fluvial depositional systems of the Carrizo-upper Wilcox in south Texas, Gulf Coast 

Association of Geological Societies Transactions, v. 33, p. 281‒287.

Harrelson, D.W., 1989, Hydrocarbon occurrences in igneous and metamorphic rocks—The plays of the 

1990’s: Gulf Coast Association of Geological Societies Transactions, v. 39, p. 85‒95.

Herrmann, L.A., Lott, J.A., and Dave, R.E., 1999, Ruston field—U.S.A. Gulf Coast Basin, Louisiana:

American Association of Petroleum Geologists Search and Discovery Article #91022, 1 p.

Hill, R.T., 1891, The Comanche Series of the Texas-Arkansas region: Geological Society of America 

Bulletin, v. 2, p. 503‒528.

Hobday, D.K., Morton, R.A., and Collins, E.W., 1979, The Queen City Formation in the East Texas 

embayment—A depositional record of riverine, tidal and wave interaction: Gulf Coast Association of 

Geological Societies, Transactions, v. 29, p. 136‒146.

Hughes, D.J., 1968, Salt tectonics as related to several Smackover fields along the northeast rim of the 

Gulf of Mexico Basin: Gulf Coast Association of Geological Societies Transactions, v. 18, p. 320‒330.

IHS Energy Group, 2010 [includes data current as of December 23, 2009], PIDM relational U.S. well 

data: IHS Energy Group, database available from IHS Energy Group, 15 Inverness Way East, D205, 

Englewood, CO 80112, U.S.A.

IHS Energy Group, 2011, ENERDEQ U.S. well data: IHS Energy Group, online database available from 

IHS Energy Group, 15 Inverness Way East, D205, Englewood, CO 80112, U.S.A., accessed January 

20, 2011. 

Imlay, R.W., 1945, Subsurface formations of South Texas: American Association of Petroleum 

Geologists Bulletin, v. 29, no. 10, p. 1416‒1469.

Kane, W.G., and Gierhart, G.B., 1935, Areal geology in northeastern Mexico: American Association of 

Petroleum Geologists Bulletin, v. 19, p. 1357‒1388.

Keith, B.D., and Pittman, E.D., 1983, Bimodal porosity in oolitic reservoir—Effect on productivity and 

log response, Rodessa Limestone (Lower Cretaceous) East Texas Basin: American Association of 

Petroleum Geologists Bulletin, v. 67, no. 9, p. 1391‒1399.

Kerans, C., and Loucks, R.G., 2002, Stratigraphic setting and controls on occurrence of high-energy 

carbonate beach deposits—Lower Cretaceous of the Gulf of Mexico: Gulf Coast Association of 

Geological Societies Transactions, v. 52, p. 517–526.

Kerans, C., and Loucks, R.G., 2003, Evolution of late Aptian/Albian carbonate platforms of the northwest 

Gulf of Mexico, Gulf Coast Section of the Society of Economic Paleontologists and Mineralogists and 

South Texas Geologic Society Symposium, San Antonio, Tex., April 11‒12, 2003, Proceedings: San 

Antonio, Tex., Gulf Coast Section of the Society of Economic Paleontologists and Mineralogists and 

South Texas Geologic Society, p. 79‒83.

Kharaka, Y.K., and Hanor, J.S., 2007, Deep fluids in the continents—I. Sedimentary basins, in Drever, 

J.I., ed., Surface and ground water, weathering and soils: Kidlington, Oxford, Elsevier Ltd., Treatise on 

Geochemistry, v. 5, p. 1‒48.

King, D.T., Jr., 1994, Upper Cretaceous depositional sequences in the Alabama Gulf coastal plain—Their 

characteristics, origin, and constituent clastic aquifers: Journal of Sedimentary Research, v. B64, no. 2, 

p. 258‒265.

Lawless, P.N., Fillon, R.H., and Lytton, R.G., III, 1997, Gulf of Mexico Cenozoic biostratigraphic, 

lithostratigraphic, and sequence stratigraphic event chronology: Gulf Coast Association of Geological 

Societies Transactions, v. 47, p. 271‒282.

Leggat, E.R., 1957, Geology and ground-water resources of Tarrant County, Texas: Texas Board of Water 

Engineers Bulletin No. 5709, 181 p.
71

Loucks, R.G, 2002, Controls on reservoir quality in platform-interior limestones around the Gulf of 

Mexico—Example from the Lower Cretaceous Pearsall Formation in South Texas: Gulf Coast 

Association of Geological Societies Transactions, v. 52, p. 659‒672.

Loucks, R.G., Bebout, D.G., and Galloway, W.E., 1979, Relationship of porosity formation and 

preservation to sandstone consolidation history—Gulf Coast lower Tertiary Frio Formation: Gulf Coast 

Associations of Geological Societies Transactions, 17, p. 109‒120.

Loucks, R.G., Abel, C., Ver Hoeve, M., 1996, Paleostructure association, lithofacies architecture, and 

reservoir quality of the upper James Lime (Pearsall Fm, Lower Cretaceous) in the Poplarville field, 

Pearl River Co., Mississippi: Gulf Coast Association of Geological Societies Transactions v. 46, 

p. 235‒448.

Loucks, R.G., and Kerans, C., 2003, Lower Cretaceous Glen Rose “patch reef” reservoir in the Chittim 

field, Maverick County, south Texas: Gulf Coast Association of Geological Societies Transactions, v. 

53, p. 490‒503.

Louisiana Department of Natural Resources, 2011, SONRIS database: Louisiana Department of Natural 

Resources, online database available from Louisiana Department of Natural Resources, accessed May 

2011, http://sonris.com/.

Mahbubullah, A.M., 1989, Distribution of facies, depositional, and diagenetic history of Knowles 

Limestone (Cotton Valley Group—Late Jurassic), De Soto Parish, Louisiana: American Association of 

Petroleum Geologists Search and Discovery Article #20000, 14 p.

Maher, J.C., Applin, E.R., and American Association of Petroleum Geologists Committee on 

Stratigraphic Correlations, 1968, Correlation of subsurface Mesozoic and Cenozoic rocks along the 

eastern Gulf Coast: Tulsa, Okla., American Association of Petroleum Geologists Cross Section 

Publication 6, 24 p.

Mancini, E.A., 2010, Jurassic depositional systems, facies, and reservoirs of the northern Gulf of Mexico:

Gulf Coast Association of Geological Societies Transactions, v. 60, p. 481‒486.

Mancini, E.A., and Benson, D.J., 1980, Regional stratigraphy of Upper Jurassic Smackover carbonates of 

southwest Alabama: Gulf Coast Association of Geological Societies Transactions, v. 30, p. 151‒165.

Mancini, E.A., Mink, R.M., Bearden, B.L., Mann, S.D., and Bolin, D.E., 1990, Desert environments and 

petroleum geology of the Norphlet Formation, Hatter's Pone field, Alabama, in Barwis, J.H., 

McPherson, J.G., and Studlick, J.R., eds., Sandstone petroleum reservoirs: New York City, SpringerVerlag, p. 153‒180.

Mancini, E.A., Mink, R.M., Tew, B.H., Kopaska-Merkel, D.C., and Mann, S.D., 1991, Upper Jurassic 

Smackover oil plays in Alabama, Mississippi and the Florida panhandle: Gulf Coast Association of 

Geological Societies Transactions, v. 41, p. 475‒480.

Mancini, E.A., Badali, Marcello, Puckett, T.M., Llinas, J.C., and Parcell, W.C., 2001, Mesozoic carbonate 

petroleum systems in the northeastern Gulf of Mexico area, in Fillon, R.H., Rosen, N.C., and Weimer, 

Paul, eds., Petroleum systems of deep-water basins—Global and Gulf of Mexico experience, 

GCSSEPM Bob F. Perkins Research Conference, December 2‒5, 2001, Houston, Tex., p. 423‒451, 

CD-ROM.

Mancini, E.A., and Puckett, T.M., 2005, Upper Jurassic and Cretaceous transgressive-regressive (T-R) 

cycles, northern Gulf of Mexico, USA: Stratigraphy, v. 2, p. 31‒48.

Mancini, E.A., and Scott, R.W., 2006, Sequence stratigraphy of Comanchean Cretaceous outcrop strata of 

northeast and south-central Texas—Implications for enhanced petroleum exploration: Gulf Coast 

Association of Geological Societies Transactions, v. 56, p. 539‒550.

Mancini, E.A., Li, Peng, Goddard, D. A., Ramirez, V., and Talukdar, S.C., 2008a, Mesozoic (Upper 

Jurassic‒Lower Cretaceous) deep gas reservoir play, central and eastern Gulf coastal plain: American 

Association of Petroleum Geologists Bulletin, v. 92, no. 3, p. 283‒308.
72

Mancini, E.A., Obid, J., Badali, M., Liu, K., and Parcell, W.C., 2008b, Sequence-stratigraphic analysis of 

Jurassic and Cretaceous strata and petroleum exploration in the central and eastern Gulf coastal plain, 

United States: American Association of Petroleum Geologists Bulletin, v. 92, no. 12, p. 1655‒1686.

Marzano, M.S., 1988, Controls on permeability for unconsolidated sands from conventional core data, 

offshore Gulf of Mexico: Gulf Coast Association of Geological Societies Transactions, v. 38, 

p. 113‒120.

Maxwell, J.C., 1964, Influence of depth, temperature, and geologic age on porosity of quartzose 

sandstone: American Association of Petroleum Geologists Bulletin, v. 48, no. 5, p. 697–709.

McFarlan, Edward, Jr., and Menes, L.S., 1991, Lower Cretaceous, in Salvador, A., ed., The geology of 

North America, The Gulf of Mexico Basin: Geological Society of America, v. J, p. 181‒204.

Miller, J.A., 1990, Groundwater atlas of the United States—Alabama, Florida, Georgia, and South 

Carolina: U.S. Geological Survey Hydrologic Atlas 730‒G, 134 p.

Miller, K.G., Kominz, M.A., Browning, J.V., Wright, J.D., Mountain, G.S., Katz, M.E., Sugarman, P.J., 

Cramer, B.S., Christie-Blick, Nicholas, Pekar, S.F., 2005, The Phanerozoic record of global sea-level 

change: Science, v. 310, p. 1293‒1298.

Mink, R.M, Tew, B.H., Mann, S.D., Bearden, B.L., and Mancini, E.A., 1990, Norphlet and pre-Norphlet 

geologic framework of Alabama and panhandle Florida coastal waters area and adjacent Federal waters 

area: Geological Survey of Alabama Bulletin, v. 140, 58 p.

Montgomery, S.L., Petty, A.J., and Post, P.J., 2002, James Limestone, northeastern Gulf of Mexico—

Refound opportunity in a Lower Cretaceous trend: American Association of Petroleum Geologists 

Bulletin, v. 86, no. 3, p. 381‒398.

Moore, C.H., 1997, Developments in sedimentology 46—Carbonate diagenesis and porosity (2nd ed.):

Amsterdam, The Netherlands, Elsevier, 338 p.

Morton, R.A., Jirik, L.A., and Galloway, W.E., 1988, Middle-upper Miocene depositional sequences of 

the Texas coastal plain and continental shelf—Geologic framework, sedimentary facies, and 

hydrocarbon plays: University of Texas at Austin, Bureau of Economic Geology Report of 

Investigations No. 174, 40 p.

Murray, R.C., 1960, Origin of porosity in carbonate rocks: Journal of Sedimentary Petrology, v. 30, no. 1, 

p. 59‒84.

Nehring Associates, Inc., 2010 [data current as of December 2008], The significant oil and gas fields of 

the United States: Colorado Springs, Colo., Nehring Associates, Inc., database available from Nehring 

Associates, Inc., P.O. Box 1655, Colorado Springs, CO 80901, U.S.A.

Nehring, R., 1991, Oil and gas resources, in Salvador, A., ed., The geology of North America—The Gulf 

of Mexico Basin: Geological Society of America, v. J, 445‒494.

Nelson, P.H., and J.E. Kibler, 2003, A catalog of porosity and permeability from core plugs in siliciclastic 

rocks: U.S. Geological Survey Open-File Report 03‒420, 7 p.

Nicot, J.P., and Hovorka, S., 2009, Leakage pathways from potential CO2 storage sites and importance of 

open traps—Case of the Texas Gulf Coast, in Grobe, M., Pashin, J.C., and Dodge, R.L., eds., Carbon 

dioxide sequestration in geological media—State of the science: American Association of Petroleum 

Geologists Studies in Geology 59, p. 321–334.

Nordstrom, P.L., 1982, Occurrence, availability, and chemical quality of groundwater in the Cretaceous 

aquifers of north-central Texas: Austin, Texas Department of Water Resources, vol. 1.

Payne, J.N., 1968, Hydrologic significance of the lithofacies of the Sparta Sand in Arkansas, Louisiana, 

Mississippi, and Texas: U.S. Geological Survey Professional Paper 569‒A, 17 p.

Pearson, K.M., 2010, Geologic controls on Austin Chalk oil and gas production—Understanding a dual 

conventional-continuous accumulation: Gulf Coast Association of Geological Societies Transactions, 

v. 60, p. 557‒570.
73

Pearson, K.M., Dubiel, R.F., Pearson, O.N., and Pitman, J.K., 2011, Assessment of undiscovered oil and 

gas resources of the Upper Cretaceous Austin Chalk and Tokio and Eutaw Formations, Gulf Coast, 

2010: U.S. Geological Survey Fact Sheet 2011–3046, 2 p.

Perkins, B.F., 1960, Biostratigraphic studies in the Comanche (Cretaceous) Series of northern Mexico and 

Texas: Geological Society of America Memoir 83, 183 p.

Pettijohn, R.A., Weiss, J.S., and Williamson, A.K., 1988, Dissolved-solids concentrations and water 

temperatures for aquifers in the Gulf Coast aquifer systems, south-central United States: U.S. 

Geological Survey Water-Resources Investigations Report 88-4082, scale 1:3,500,000, 5 sheets.

Petty, A.J., 1995, Ferry Lake, Rodessa, and Punta Gorda Anhydrite bed correlation, Lower Cretaceous, 

offshore eastern Gulf of Mexico: Gulf Coast Association of Geological Societies Transactions v. 45, 

p. 487‒493.

Petty, A.J., 1997, Lower Tuscaloosa clastic facies distribution (Upper Cretaceous), Federal and State 

waters, eastern Gulf of Mexico: Gulf Coast Association of Geological Societies Transactions, v. 47, 

p. 451‒462.

Petty, A.J., 1999, Petroleum exploration and stratigraphy of the Lower Cretaceous James Limestone 

(Aptian) and Andrew Formation (Albian)—Main Pass, Viosca Knoll, and Mobile areas, northeastern 

Gulf of Mexico: Gulf Coast Association of Geological Societies Transactions, v. 49, p. 440‒451.

Pittman, J.G., 1985, Correlation of beds within the Ferry Lake Anhydrite of the Gulf coastal plain: Gulf 

Coast Association of Geological Societies Transactions, v. 35, p. 251‒260.

Pitman, J.K., 2011, Reservoirs and petroleum systems of the Gulf Coast: American Association of 

Petroleum Geologists, Datapages GIS Open Files, accessed August 1, 2012,

http://www.datapages.com/AssociatedWebsites/GISOpenFiles/ReservoirsandPetroleumSystemsoftheGu

lfCoast.aspx.

Pitman, J.K., Charpentier, R.R., Cook, T.A., Dubiel, R.F., Kibler, J., Klett, T.R., Nelson, P.H., Pollastro, 

R.M., and Schenk, C.J., 2007, Assessment of undiscovered gas resources in the Upper Cretaceous 

Tuscaloosa and Woodbine Formations, Western Gulf Province of the Gulf Coast Region, Louisiana and 

Texas, 2007: U.S. Geological Survey Fact Sheet 2006‒3146, 2 p.

Rainwater, E.H., 1964, Transgressions and regressions in the Gulf Coast Tertiary: Gulf Coast Association 

of Geological Societies Transactions, v. 14, p. 217–230.

Rainwater, E.H., 1971, Possible future petroleum potential of Lower Cretaceous, western Gulf Basin:

American Association of Petroleum Geologists Memoir 15, v. 2, p. 901‒926.

Renken, R.A., 1996, Hydrogeology of the Southeastern Coastal Plain aquifer system in Mississippi, 

Alabama, Georgia, and South Carolina: U.S. Geological Survey Professional Paper 1410‒B, 111 p. 

Rhodes, J.A., and Maxwell, G.B., 1993, Jurassic stratigraphy of the Wiggins arch, Mississippi: Gulf Coast 

Association of Geological Societies Transactions, v. 43, p. 333‒344.

Ricoy, J.U., and Brown, L.F., Jr., 1977, Depositional systems in the Sparta Formation (Eocene) Gulf 

Coast Basin of Texas: Gulf Coast Association of Geological Societies Transactions, v. 27, p. 103‒118.

Roberts, J.L, and Lock, B.E., 1988, The Rodessa Formation in Bossier Parish, Louisiana—Lithofacies 

analysis of a hydrocarbon-productive shallow water clastic-carbonate sequence: Gulf Coast Association 

of Geological Societies Transactions, v. 38, p. 103‒111.

Rose, P.R., 1972, Edwards Group, surface and subsurface, central Texas: University of Texas at Austin, 

Bureau of Economic Geology Report of Investigations No. 74, 197 p.

Rosen, R.N., and Rosen, N.C., 2008, Biostratigraphy and chronostratigraphy of the subsurface Cretaceous 

of the Gulf Coast Basin, emphasizing the Woodbine-Tuscaloosa: Gulf Coast Section SEPM Foundation 

Special Publication No. 3, 63 p.

Ryder, P.D., 1996, Oklahoma and Texas, in Groundwater atlas of the United States: U.S. Geological 

Survey Hydrologic Investigations Atlas 730‒E, 300 p.
74

Salvador, A., 1987, Late Triassic-Jurassic paleogeography and origin of Gulf of Mexico Basin: American 

Association of Petroleum Geologists Bulletin, v. 71, no. 4, p. 419‒451.

Salvador, A., 1991a, Origin and development of the Gulf of Mexico Basin, in Salvador, A., ed., The 

geology of North America—The Gulf of Mexico Basin: Geological Society of America, v. J, 

p. 389‒444.

Salvador, A., 1991b, Triassic-Jurassic, in Salvador, A., ed., The geology of North America—The Gulf of 

Mexico Basin: Geological Society of America, v. J, p. 131‒180.

Salvador, A. and Quezada-Muñeton, J.M., 1991, Stratigraphic correlation chart, in Salvador, A., ed., The 

geology of North America—The Gulf of Mexico Basin: Geological Society of America, v. J, plate 5.

Sams, R.H., 1982, Gulf Coast stratigraphic traps in the Lower Cretaceous carbonates: Oil and Gas 

Journal, v. 80, p. 177‒187.

Saunders, J.A., and Harrelson, D.W., 1992, Age and petrology of the Jackson dome igneous-volcanic 

complex, Mississippi—Implications for the tectonic history of the Mississippi Salt Dome Basin: Gulf 

Coast Association of Geological Societies Transactions, v. 42, p. 659‒667.

Sawyer, D.S, Buffler, R.T., Pilger, Jr., R.H., 1991, The crust under the Gulf of Mexico Basin, in Salvador, 

A., ed., The geology of North America—The Gulf of Mexico Basin: Geological Society of America, 

v. J, p. 53‒72.

Schenk, C.J., and Schmoker, J.W., 1993, Role of halite in the evolution of sandstone porosity, Upper 

Jurassic Norphlet Formation, Mississippi Salt Basin: American Association of Petroleum Geologists 

Search and Discovery Article #90989. 

Schenk, C.J., and Viger, R.J., 1995a, Western Gulf Province (047), in Gautier, D.L., Dolton, G.L., 

Takahashi, K.I., and Varnes, K.L., eds., 1995 National assessment of United States oil and gas 

resources—Results, methodology, and supporting data: U.S. Geological Survey Digital Data Series 30, 

44 p.

Schenk, C.J., and Viger, R.J., 1995b, East Texas Basin Province (048) and Louisiana-Mississippi Salt 

Basins Province (049), in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 

National assessment of United States oil and gas resources—Results, methodology, and supporting 

data: U.S. Geological Survey Digital Data Series 30, 42 p.

Scott, R.J., 2004, The Maverick Basin—New Technology—New Success: Gulf Coast Association of 

Geological Societies Transactions, v. 54, p. 603‒620.

Scott, R.W., 1990, Models and stratigraphy of mid-Cretaceous reef communities, Gulf of Mexico, Tulsa, 

OK: Society for Sedimentary Geology, Concepts in Sedimentology and Paleontology, v. 2, 99 p.

Scott, R.W., Laali, H., and Fee, D.W., 1975, Density-current strata in Lower Cretaceous Washita Group, 

north-central Texas: Journal of Sedimentary Petrology, v. 45, no. 2, p. 562‒575.

Seni, S.J., 1981, Depositional systems of the Lower Cretaceous Paluxy Formation, East Texas Basin, in

Kreitler, C.W., Collins, E.W., Davidson, E.D., Jr., Dix, O.R., Donaldson, G.A., Dutton, S.P., Fogg, 

G.E., Giles, A.B., Harris, D.W., Jackson, M.P.A., Lopez, C.M., McGowen, M.K., Muehlberger, W.R., 

Pennington, W.D., Seni, S.J., Wood, D.H., and Wuerch, H.V., eds., Geology and geohydrology of the 

East Texas Basin—A report on the progress of nuclear waste isolation feasibility studies: The 

University of Texas at Austin, Bureau of Economic Geology Geological Circular 81-7, p. 12–20.

Shelburne, O.B., Jr., 1959, A stratigraphic study of the Kiamichi Formation in central Texas: University 

of Texas at Austin, Bureau of Economic Geology Publication No. 5905, p. 105‒130.

Snedden, J.W., and Kersey, D.G., 1982, Depositional environments and gas production trends Olmos 

Sandstone, Upper Cretaceous, Webb County, Texas: Gulf Coast Association of Geological Societies 

Transactions, v. 32, p. 497‒518.

Stoudt, D.L., McCulloh, R.P., and Eversull, L.G., 1990, Gulf Coast regional cross section: Tulsa, Okla., 

American Association of Petroleum Geologists, 3 p.
75

Swain, F.M., 1944, Stratigraphy of Cotton Valley beds of northern Gulf Coast plain: American 

Association of Petroleum Geologists Bulletin, v. 28, no. 5, p. 577‒614.

Sweezey, C.S., and Sullivan, E.C., 2004, Stratigraphy and sedimentology of the Upper Cretaceous 

(Campanian) Anacacho Limestone, Texas, USA: Cretaceous Research, v. 25, p. 473‒497.

Talbert, S.J., and Atchley, S.C., 2000, Sequence stratigraphy of the Lower Cretaceous (Albian) 

Fredericksburg Group, central and north Texas: Gulf Coast Association of Geological Societies 

Transactions, v. 50, p. 369‒378.

Tew, B.H., Mink, R.M., Mann, S.D., Bearden, B.L., and Mancini, E.A., 1991, Geologic framework of 

Norphlet and pre-Norphlet strata of the onshore and offshore eastern Gulf of Mexico area: Gulf Coast 

Association of Geological Societies Transactions, v. 41, p. 590‒600.

Todd, J.D., and Roper, F.C., 1940, Sparta-Wilcox trend, Texas and Louisiana: American Association of 

Petroleum Geologists Bulletin, v. 24, p. 701‒715.

Trowbridge, A.C., 1932, Tertiary and Quaternary geology of the lower Rio Grande region of Texas: U.S. 

Geological Survey Bulletin 837, p. 141‒156.

Tye, R.S, Moslow, T.F., Kimbrell, W.C., and Wheeler, C.W., 1991, Lithostratigraphy and production 

characteristics of the Wilcox Group (Paleocene-Eocene) in central Louisiana: The American 

Association of Petroleum Geologists, Bulletin, v. 75, no. 11, p. 1675‒1713.

Tyler, N., Gholston, J.C., and Ambrose, W.A., 1987, Oil recovery in a low-permeability, wavedominated, Cretaceous, deltaic reservoir, Big Wells (San Miguel) field, south Texas: American 

Association of Petroleum Geologists Bulletin, v. 71, no. 10, p. 1171‒1195.

Tyler, R., and Scott, A.R.. 1999, Defining coalbed methane exploration fairways in east-central Texas: 

University of Texas at Austin, Bureau of Economic Geology, topical report prepared for the U.S. 

Geological Survey under cooperative agreement no. 99HQAG0018 (NCRDS), 74 p.

U. S. Department of Energy, 2011, Domestic unconventional fossil energy resource opportunities and 

associated technology applications: U. S. Department of Energy Report to Congress, 95 p. 

U.S. Energy Information Administration, 2011, Review of emerging resources—U.S. shale gas and shale 

oil plays: Washington, D.C., U.S. Department of Energy, 105 p.

U.S. Environmental Protection Agency (EPA), 2009, Safe Drinking Water Act (SDWA): Washington, 

D.C., U.S. Environmental Protection Agency Web site, accessed January 14, 2009, 

http://www.epa.gov/ogwdw/sdwa/index.html.

U.S. Environmental Protection Agency (EPA), 2010, Federal requirements under the Underground 

Injection Control (UIC) for carbon dioxide (CO2) geologic sequestration (GS) wells: Washington, D.C., 

U.S. Environmental Protection Agency Web site, accessed October 15, 2012,

http://water.epa.gov/type/groundwater/uic/class6/gsregulations.cfm.

U.S. Environmental Protection Agency (EPA), 2013, Geologic sequestration of carbon dioxide, 

underground injection control (UIC) program class VI well site characterization guidance: Washington, 

D.C., U.S. Environmental Protection Agency Web site, accessed May 16, 2013,

http://water.epa.gov/type/groundwater/uic/class6/gsguidedoc.cfm.

U.S. Geological Survey (USGS), 2010, National water information system: U.S. Geological Survey online database, accessed on September 17, 2012, http://waterdata.usgs.gov/nwis.

U.S. Geological Survey (USGS) Cotton Valley Assessment Team, 2003, 2002 Assessment of 

undiscovered oil and gas resources of the Jurassic-Cretaceous Cotton Valley Group, Jurassic 

Smackover Interior Salt Basins Total Petroleum System, in the Louisiana-Mississippi Salt Basins 

Province of the northern Gulf Coast region: U.S. Geological Survey Fact Sheet 047‒03, 2 p.

U.S. Geological Survey (USGS) Gulf Coast Region Assessment Team, 2006, Petroleum systems and 

geologic assessment of undiscovered oil and gas, Cotton Valley Group and Travis Peak-Hosston 

Formations, East Texas Basin and Louisiana-Mississippi Salt Basins Provinces of the northern Gulf 

Coast region: U.S. Geological Survey Digital Data Series 69‒E, 52 p.
76

U.S. Geological Survey (USGS) Navarro and Taylor Groups Assessment Team, 2004, 2003 Assessment 

of undiscovered oil and gas resources in Upper Cretaceous Navarro and Taylor Groups, Western Gulf 

Province, Gulf Coast region, Texas: U.S. Geological Survey Fact Sheet 2004‒3114, 2 p.

U.S. Geological Survey (USGS) Navarro and Taylor Groups Assessment Team, 2006, Petroleum systems 

and geologic assessment of undiscovered oil and gas, Navarro and Taylor Groups, Western Gulf 

Province, Texas: U.S. Geological Survey Digital Data Series 69‒H, 47 p..

U.S. Geological Survey (USGS) Travis Peak-Hosston Assessment Team, 2003, 2002 Assessment of 

undiscovered oil and gas resources—Cretaceous Travis Peak and Hosston Formations, Jurassic 

Smackover Interior Salt Basins Total Petroleum System, Louisiana-Mississippi Salt Basins Province, 

northern Gulf Coast region: U.S. Geological Survey Fact Sheet 085‒03, 2 p.

Valentine, B.J., and Dennen, K.O., eds., 2012, Shallow coal exploration drill-hole data—Alabama, 

Georgia, Kentucky, Louisiana, Mississippi, Missouri, North Carolina, South Carolina, Tennessee, and 

Texas: U.S. Geological Survey Open-File Report 2011–1261, 102 p. 

Walker, J.D., Geissman, J.W., Bowring, S.A., and Babcock, L.E., compilers, 2012, Geologic time scale,

v. 4.0: Geological Society of America, 1 p., accessed May 23, 2013, 

http://www.geosociety.org/science/timescale/timescl.pdf.

Warwick, P.D., 2011, USGS assessment of undiscovered oil and gas resources in the Lower Cretaceous 

Greater Glen Rose carbonate shelf and reef interval, U.S. onshore lands and State waters of the Gulf of 

Mexico [abs.]: American Association of Petroleum Geologists Search and Discovery Article #90124, 

American Association of Petroleum Geologists Annual Convention and Exhibition, April 10‒13, 2011, 

Houston, Texas, 1 p.

Warwick, P.D., SanFilipo, J.R., Crowley, S.S., Thomas, R.E., Fried, J., and Tullu, J.K., 1997, Map 

showing outcrop of the coal-bearing units and land use in the Gulf Coast region: U.S. Geological 

Survey Open-File Report 97‒172, 1 sheet.

Warwick, P.D., Coleman, J.L., Hackley, P.C., Hayba, D.O., Karlsen, A.W., Rowan, E.L., and Swanson, 

S.M., 2007, USGS assessment of undiscovered oil and gas resources in Paleogene strata of the U.S. 

Gulf of Mexico coastal plain and State-waters, in Kennan, L., Pindell, J., and Rosen, N.C., eds., The 

Paleogene of the Gulf of Mexico and Caribbean Basins—Processes, events, and petroleum systems: 

Society of Economic Paleontologists and Mineralogists, Gulf Coast Section Foundation 27th Annual 

Research Conference, p. 2‒44. 

Webb, E.J., 1984, Sedimentology of the Upper Cretaceous Coffee Sands in north central Mississippi: Gulf 

Coast Association of Geological Societies Transactions, v. 34, p. 277‒286.

Webster, R.E., Luttner, D., and Liu, L., 2008, Fairway James Lime field, East Texas—Still developing 

after 48 years: American Association of Petroleum Geologists Search and Discovery Article #110061, 

40 p.

Weeks, W.B., 1938, South Arkansas stratigraphy with emphasis on the older coastal plain beds: American 

Association of Petroleum Geologists Bulletin, v. 22, no. 8, p. 953‒983.

Wendlandt, E.A., and Knebel, G.M., 1926, Lower Claiborne of east Texas, with special reference to 

Mount Sylvan dome and salt movements: American Association of Petroleum Geologists Bulletin, 

v. 13, p. 1347‒1375.

Williamson, J.D.M., 1959, Gulf Coast Cenozoic history: Gulf Coast Association of Geological Societies 

Transactions, v. 9, p. 15–29.

Wilmarth, M.G., 1938, [Geologic Names Committee remarks], in Wilmarth, M.G., ed., Lexicon of 

geologic names of the United States (including Alaska): U.S. Geological Survey Bulletin 896, 2396 p.

Wilson, E.J., Johnson, T.L., and Keith, D.W., 2003, Regulating the ultimate sink—Managing the risks of 

geologic CO2 storage: Environmental Science and Technology, v. 37, no. 16, p. 3476–3483.
77

Winker, C.D., and Buffler, R.T., 1988, Paleogeographic evolution of early deep-water Gulf of Mexico 

and margins, Jurassic to middle Cretaceous (Comanchean): American Association of Petroleum 

Geologists Bulletin, v. 72, no. 3, p. 318‒346.

Witrock, R.B., Friedmann, A.R., Galluzzo, J.J., Nixon, L.D., Post, P.J., Ross, K.M., 2003, 

Biostratigraphic chart of the Gulf of Mexico offshore region, Jurassic to Quaternary: U.S. Department 

of the Interior Minerals Management Service, 1 sheet.

Yurewicz, D.A., Marler, T.B., Meyerholtz, K.A., Siroky, F.X., 1993, Early Cretaceous carbonate 

platform, north rim of the Gulf of Mexico, Mississippi and Louisiana, in Simon, J.A.T., Scott, R.W., 

and Masse, J-P., eds., Cretaceous carbonate platforms: American Association of Petroleum Geologists 

Memoir 56, p. 81‒96.

Yurewicz, D.A., Chuchla, R.J., Richardson, M., Pottorf, R.J., Gray, G.G., Kozar, M.G., and Fitchen, 

W.M., 1997, Hydrocarbon generation and migration in the Tampico-Misantla Basin and Sierra Madre 

Oriental, east-central Mexico—Evidence from an exhumed oil field in the Sierra de El Abra, in

Sedimentation and diagenesis of middle Cretaceous platform margins, east central Mexico: American 

Association of Petroleum Geologists Annual Meeting Field Trip Guidebook, Dallas Geological Society 

and SEPM, 24 p.

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