Class II Underground Injection Control Well Data for 2010–2013 by

Geologic Zones of Completion, Oklahoma

Open-File Report (OF1-2014)

Kyle E. Murray

Oklahoma Geological Survey

University of Oklahoma

100 East Boyd Street

Norman, OK 73019
Oklahoma Geological Survey, Open-File Report Disclaimer:

Open-File Reports are used for the dissemination of information that fills a public need and

are intended to make the results of research available at the earliest possible date. Because of

their nature and possibility of being superseded, an Open-File Report is intended as a preliminary

report not as a final publication. Analyses presented in this article are based on information

available to the author, and do not necessarily represent the views of the Oklahoma Geological

Survey, the University of Oklahoma, their employees, or the State of Oklahoma. The accuracy of

the information contained herein are not guaranteed and the mention of trade names are not an

endorsement by the author, the Oklahoma Geological Survey, or the University of Oklahoma.

Suggested Citation:

Murray KE (2014) Class II Underground Injection Control Well Data for 2010–2013 by

Geologic Zones of Completion, Oklahoma. Oklahoma Geological Survey Open-File Report

(OF1-2014). Norman, OK. pp. 32.
Contents

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

1. Introduction ............................................................................................................................. 2

1.1. Underground Injection Control (UIC) Well Designations............................................... 2

1.2. Potential for Induced Seismicity from Fluid Injection..................................................... 3

1.3. Objectives......................................................................................................................... 3

2. Methods................................................................................................................................... 3

2.1. Compile UIC Well Locations and Injection Data ............................................................ 3

2.2. Quality Assurance Quality Control (QAQC) of UIC Data .............................................. 3

2.3. Attribute Injection Zones for Wells ................................................................................. 4

2.4. Summarize Volumes by Zone and County ...................................................................... 4

2.5. Obtain Earthquake Data for 2010–2013........................................................................... 4

3. Results and Discussion ............................................................................................................ 5

3.1. Highest Volume Class II UIC Wells................................................................................ 5

3.2. SWD Wells and Volumes by Geologic Zone of Completion .......................................... 5

3.3. EORI Wells and Volumes by Geologic Zones of Completion ........................................ 6

3.4. Temporal Trends in SWD by County .............................................................................. 7

3.5. Injection Depths and Pressures of SWD .......................................................................... 7

3.6. Temporal Trends in EORI by County.............................................................................. 8

3.7. Seismic Activity in Oklahoma ......................................................................................... 9

4. Future Directions..................................................................................................................... 9

5. References ............................................................................................................................... 9

Abbreviations, Units, and Definitions .......................................................................................... 11

Tables

Table 1 Number of active SWD (i.e., 2D) wells in Oklahoma, by zone of completion................. 5

Table 2 Volume of water injected into SWD (i.e., 2D) wells in Oklahoma, by zone of completion

......................................................................................................................................................... 6

Table 3 Number of active EORI (i.e., 2R) wells in Oklahoma, by zone of completion................. 6

Table 4 Volume of water injected into EORI (i.e., 2R) wells in Oklahoma, by zone of completion

......................................................................................................................................................... 6

Table 5 SWD (i.e., 2D) volumes by county.................................................................................... 7

Table 6 Median wellhead pressures reported for active SWD (i.e., 2D) wells, by completion zone

......................................................................................................................................................... 8

Table 7 EORI (i.e., 2R) volumes by county ................................................................................... 8
Figures

Figure 1 Map of SWD wells and relative volumes of water injected into SWD Class II UIC wells

(i.e., 2D) during 2010. Chart of SWD well volumes in 2010 by county. ......................... 12

Figure 2 Map of SWD wells and relative volumes of water injected into SWD Class II UIC wells

(i.e., 2D) during 2011. Chart of SWD well volumes in 2011 by county. ......................... 13

Figure 3 Map of SWD wells and relative volumes of water injected into SWD Class II UIC wells

(i.e., 2D) during 2012. Chart of SWD well volumes in 2012 by county. ......................... 14

Figure 4 Map of SWD wells and relative volumes of water injected into SWD Class II UIC wells

(i.e., 2D) during 2013. Chart of SWD well volumes in 2013 by county. ......................... 15

Figure 5 Map of EORI wells and relative volumes of water injected into EORI Class II UIC

wells (i.e., 2R) during 2010. Chart of EORI well volumes in 2010 by county. ............... 16

Figure 6 Map of EORI wells and relative volumes of water injected into EORI Class II UIC

wells (i.e., 2R) during 2011. Chart of EORI well volumes in 2011 by county. ............... 17

Figure 7 Map of EORI wells and relative volumes of water injected into EORI Class II UIC

wells (i.e., 2R) during 2012. Chart of EORI well volumes in 2012 by county. ............... 18

Figure 8 Map of EORI wells and relative volumes of water injected into EORI Class II UIC

wells (i.e., 2R) during 2013. Chart of EORI well volumes in 2013 by county. ............... 19

Figure 9 Chart of UIC well volumes in 2010 by geologic zone of completion............................ 20

Figure 10 Chart of UIC well volumes in 2011 by geologic zone of completion.......................... 21

Figure 11 Chart of UIC well volumes in 2012 by geologic zone of completion.......................... 22

Figure 12 Chart of UIC well volumes in 2013 by geologic zone of completion.......................... 23

Figure 13 Depths, below land surface, for completion intervals of 2010–2013 active SWD (i.e.,

2D) wells in Oklahoma ..................................................................................................... 24

Figure 14 Wellhead injection pressure (psi) for active SWD (i.e., 2D) wells in 2010................. 25

Figure 15 Wellhead injection pressure (psi) for active SWD (i.e., 2D) wells in 2011................. 25

Figure 16 Wellhead injection pressure (psi) for active SWD (i.e., 2D) wells in 2012................. 26

Figure 17 Wellhead injection pressure (psi) for active SWD (i.e., 2D) wells in 2013................. 26

Figure 18 Map of earthquakes and relative magnitudes during 2010, data from OGS earthquake

catalog. Chart of >=3.0 magnitude earthquakes in 2010 by month.................................. 27

Figure 19 Map of earthquakes and relative magnitudes during 2011, data from OGS earthquake

catalog. Chart of >=3.0 magnitude earthquakes in 2011 by month.................................. 28

Figure 20 Map of earthquakes and relative magnitudes during 2012, data from OGS earthquake

catalog. Chart of >=3.0 magnitude earthquakes in 2012 by month.................................. 29

Figure 21 Map of earthquakes and relative magnitudes during 2013, data from OGS earthquake

catalog. Chart of >=3.0 magnitude earthquakes in 2013 by month.................................. 30

Figure 22 Number of earthquakes versus depth of focal point for 2000–2013 ............................ 31

Figure 23 Spatiotemporal comparison of change in SWD versus change in seismicity at a countyscale................................................................................................................................... 32
1

Class II Underground Injection Control Well Data for 2010–2013 by Geologic Zones of 

Completion, Oklahoma

Kyle E. Murray

Hydrogeologist

Oklahoma Geological Survey

Norman, OK 73019

e-mail: kyle.murray@ou.edu

Abstract

Water and energy resources are fundamentally connected and have created what some refer to

as the energy-water or water-energy nexus. A common goal of water and energy management is

to maximize the supply of one while minimizing the use of the other. Water management in

Oklahoma has become an important issue not only because of recurring droughts and increased

water demand, but because large volumes of saltwater are being co-produced with oil and gas

and must be properly managed. Oklahoma’s statewide co-produced water volumes were

estimated to range from 811–925 million barrels (MMbbl) from 2000–2011. In the last few

years, an estimated 40–60% of Oklahoma’s co-produced water originated from oil and gas wells

in the Mississippian play where median fluid production ratios of H2O:oil and H2O:gas were 7.4

and 9.8, respectively. Other practices, such as dewatering in the Hunton play of central

Oklahoma, have resulted in high volumes of co-produced water and subsequently high volumes

for saltwater disposal (SWD). Seismic activity from 2009–2014 far exceeds historic seismicity

and, in a few cases, has been correlated to subsurface fluid injection in the midcontinent.

Therefore, there is an urgent need to quantify volumes and pressures of injections by geologic

zone of completion, and use this information to develop best management practices for water

that is co-produced with oil and gas.

This report is part of an ongoing effort to compile Oklahoma’s Class II underground injection

control (UIC) well data on county- and annual- scales by geologic zone of completion. 

Thousands of annual fluid injection reports and well completion reports, filed by operators with

the Oklahoma Corporation Commission (OCC), were the primary sources of data for this report. 

Data were compiled into a relational database, checked against scanned and electronic OCC

records, and then summarized at county-, state-, and annual- scales.

Because most previous studies indicate that SWD, especially into basal sedimentary strata, are

in closer proximity to basement faults, the volumes and pressures of SWD wells were more

carefully examined than enhanced oil recovery injection (EORI) wells. Statewide (excluding

Osage County) SWD volumes were 878, 991, 1067, and 1193 MMbbl from 2010–2013,

respectively, and are increasing at a rate that mimics statewide petroleum production. SWD

volumes into the Arbuckle basal sedimentary strata increased most in Alfalfa, Grant, and Woods

Counties of northern Oklahoma from 2010–2013, while SWD volumes in Kay, Lincoln, and

Creek Counties decreased substantially in that same time period. Seismic activity increased most

in Lincoln, Grant, and Seminole Counties from 2010 & 2011 to 2012 & 2013. A comparison of

temporal trends in SWD volumes for wells completed in the Arbuckle or Basement zones versus

county-scale seismicity exhibit a variety of direct and inverse correlations.
Oklahoma Geological Survey OF1-2014

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1. Introduction

Petroleum production began in Oklahoma 

before 1900 and has been continuously 

produced for more than 100 years, with oil 

peaking at ~278 million barrels of oil 

(MMBO) in 1927 and gas production 

peaking at ~399 million barrels of oil 

equivalent (MMBOE) in 1990 (Murray and 

Holland 2014). Modest volumes of oil were 

produced in Oklahoma for several decades, 

but a resurgence in production has occurred 

because of technological innovation and 

economic drivers. More than 26% of 

Oklahoma’s petroleum wells completed in 

2009 were horizontally drilled and 

hydraulically fractured, but the proportion 

appears to have increased annually with 

more than 43% being horizontal in 2011

(Murray 2013). Higher production has also 

occurred from unconventional shale plays 

and from conventional sandstone and 

carbonate reservoirs (Murray and Holland 

2014). Crude-oil production averaged 76.7 

MMBO in Oklahoma from 2010–2012, 

ranking as the 5th highest producing U.S. 

state (EIA 2014a). Gross natural-gas 

production averaged 89.3 MMBOE in 

Oklahoma from 2010–2012, ranking as the 

5th highest producing U.S. state (EIA 

2014b).

Concurrent with higher annual statewide 

petroleum production is a higher annual 

statewide co-production of water. By 

multiplying H2O:oil ratio by oil production 

and H2O:gas ratio by oil-equivalent gas 

production, Murray (2013) estimated 

Oklahoma’s statewide co-produced water 

volumes to range from 811–925 million 

barrels (MMbbl) from 2000–2011. 

Dewatering from the Hunton Lime and other

plays, such as the Mississippian of southern 

Kansas and northern Oklahoma, produce 

large volumes of water per unit of oil or gas. 

Petroleum production from the 

Mississippian has been highest in Woods, 

Alfalfa, Grant, Kay, and Osage counties in 

northern Oklahoma, so co-production of 

water may be potentially higher in this 

region.

1.1. Underground Injection Control (UIC) 

Well Designations

The underground injection control (UIC)

program was implemented by the U.S.

Environmental Protection Agency (EPA) in

the 1980s to manage and regulate fluid

injections into the subsurface. Six UIC well

designations (Class I, II, III, IV, V, and VI)

are used to manage injections from various

industries. The EPA maintains regulatory

authority over subsurface fluid injection but

may delegate authority of Class II wells to

state agencies. The Oklahoma Corporation

Commission (OCC) is delegated authority

over Class II UIC wells, except in Osage

County (i.e., Osage Nation) where EPA

maintains authority. Current regulatory

controls over Class II UIC wells were

designed to protect potable-water sources

from contamination.

Class II UIC wells are used for two basic

purposes in the oil and gas sector, enhanced

oil-recovery injection (i.e., EORI or 2R) and

salt-water disposal (i.e., SWD or 2D). UIC

wells of the 2R type are designed to inject

fluids (water and/or CO2) into the subsurface

to mobilize oil and/or gas into production

wells. During 2R injection, pressure across

the field is monitored so as not to exceed

virgin pressure conditions. UIC wells of the

2D type are designed to dispose of brine

water that was co-produced with oil and gas.

These 2D wells ideally function on a

vacuum or require low wellhead-injection

pressures. The term ‘injection’ is used

throughout this report because the wells are

part of the UIC program; however, use of

the term injection does not imply highpressure such as would be used for hydraulic

fracturing during well completion.
Oklahoma Geological Survey OF1-2014

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1.2. Potential for Induced Seismicity from 

Fluid Injection

Fluid injections, including 2R (Davis and

Pennington 1989) and 2D (Horton 2012,

Keranen et al. 2013, Nicholson and Wesson

1990) have been correlated to seismicity and

are assumed to reduce normal stress so that

movement occurs along a pre-existing fault

(Healy et al. 1968, NRC 2012, Raleigh et al.

1976). Some of the largest magnitude

earthquakes correlated with 2D injections

were centered in the midcontinent states of

Arkansas, Oklahoma, and Texas (Frohlich

2012, Horton 2012, Keranen et al. 2013).

Regardless of potential correlations,

research on the topic of induced seismicity

recognizes the uncertainty and the difficulty

in distinguishing between natural or induced

seismic events. Major limitations of

previous studies relate to the unknown

quality of UIC data including x-y location, z

elevation, zone of completion, volume, and

pressure. Integrated hydrogeologic,

structural geologic, and seismologic studies

are required because mechanisms for fluidinjection induced seismicity are related to

stresses and strength of faults, hydraulic

properties of injection zones, and pressure

diffusion (Ellsworth 2013, Holland 2013).

1.3. Objectives

Absent from the fluid-injection induced

seismicity literature are broad-scale

perspectives on fluid-injection volumes and

pressures or accurate reporting of geologic

intervals that receive those fluids. The

objectives of this research were to compile

and summarize water (e.g., brackish or

saltwater) injection volumes and wellhead

injection pressures for Class II UIC wells in

Oklahoma by geologic completion zone,

examine spatial and temporal trends for

subsurface injection from 2010–2013, and

map annual seismic activity from 2010–

2013.

2. Methods

Because disparate data for Class II UIC

program wells in Oklahoma were reported to

OCC and EPA for the 2010–2013

timeframe, multiple databases were

designed and maintained during the course

of this research. American Petroleum

Institute (API) unique identifiers for wells

(i.e., API number) were used to manage data

reported to OCC, while EPA assigned

inventory number was used for UIC wells in

Osage County, Oklahoma.

2.1. Compile UIC Well Locations and 

Injection Data

Monthly fluid-injection volumes and 

pressures for Class II UIC wells were 

obtained from the OCC (Lord 2014, Lord 

2012, OCC 2014a, OCC 2014b) and used to 

create a relational database for wells in 

Oklahoma (i.e., Oklahoma UIC database), 

excluding Osage County, from 2010–2013. 

Records were managed using API number 

when appending data to the Oklahoma UIC 

database.

Fluid injection data for Class II UIC wells 

in Osage County were obtained from the 

EPA District 6 office and used to create a 

relational Osage UIC database. Maximum 

monthly injection volumes per well were 

provided by EPA, so annual injection 

volumes were ‘overestimated’ by 

multiplying maximum monthly injection 

volume by 12 (months per year). UIC well 

records in the Osage UIC database were 

managed using an inventory number 

assigned by the EPA.

2.2. Quality Assurance Quality Control 

(QAQC) of UIC Data

Annual injection volumes and injection 

pressures in the Oklahoma UIC database 

were compared to scanned ‘Form 1012A: 

Annual Fluid Injection Reports’ that were 

submitted to the OCC by UIC operators. 

Annual volume recorded in the Oklahoma 
Oklahoma Geological Survey OF1-2014

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UIC database, before the quality assurance 

quality control (QAQC) check, included 

carbon dioxide (CO2) in units of MCF or 

Liquefied Petroleum Gas (LPG) in units of 

barrels in addition to water volumes. Thus, 

annual volumes were modified in the 

Oklahoma UIC database to represent only 

water volumes. In other cases, the operators 

reported a barrels per day (BPD) injection 

rate instead of barrels per month (BPM)

which, when annualized, was 

underrepresenting injection volume.

The Osage UIC database did not go 

through a QAQC check because more 

detailed records were only accessible in 

hard-copy at the Bureau of Indian Affairs 

(BIA) office in Pawhuska, Oklahoma and 

would require an even greater time 

commitment.

2.3. Attribute Injection Zones for Wells

Well-completion data for Oklahoma UIC 

database wells were obtained from the OCC 

well database and interactive web-site (OCC 

2014c). Injection zones were represented 

using twelve categories after Murray and 

Holland (2014): Permian, Virgilian, 

Missourian, Desmoinesian, AtokanMorrowan, Mississippian, Woodford, 

Devonian to Middle Ordovician (Dev to Mid 

Ord), Arbuckle, Basement, MultipleUndifferentiated, and Other or Unspecified. 

‘Producing’ or ‘injection’ formation(s) were 

correlated to the appropriate zone based on 

the Stratigraphic Guide to Oklahoma Oil and 

Gas Reservoirs (Boyd 2008). When 

producing or injection formation was not 

specified in the Oklahoma UIC databases, 

the completion reports (e.g., OCC’s Form 

1002A) or other digitally accessible records 

were examined for each API number in

Oklahoma. The injection formation(s) for 

the most recent completion of each API 

number was determined, when possible, and 

added as an attribute to the Oklahoma UIC 

database. When records indicated that the 

injection interval consisted of multiple 

groups or formations (e.g., Bartlesville and 

Dutcher) from more than one zone, then the 

well was attributed as ‘MultipleUndifferentiated.’ When records indicated 

that a formation (e.g., Cretaceous Niobrara) 

other than the ten designated zones was used 

for injection or the target formation was not 

discernible, then the well was attributed as 

‘Other or Unspecified’. UIC well records in 

the Oklahoma UIC database were also 

attributed with maximum injection depth 

based on deepest perforated or open-hole 

interval.

2.4. Summarize Volumes by Zone and County

Class II UIC wells were selected (i.e., 

queried) from the Oklahoma UIC database. 

Annual injection volumes were summed for 

each year from 2010–2013, after grouping 

the selected wells by injection zone (e.g., 

Permian, Virgilian), injection type (i.e., 2R 

or 2D), and county. From these queries, total 

water-injection volumes were estimated for 

each zone by county from 2010–2013.

2.5. Obtain Earthquake Data for 2010–2013

Earthquake data including date, xy 

location, depth, and magnitude were 

downloaded from the Oklahoma Geological 

Survey (OGS) Geophysical Observatory 

earthquake catalog

(http://www.okgeosurvey1.gov/pages/earthq

uakes/catalogs.php). Data were sorted and 

counted by year of origin, magnitude, or 

depth and plotted versus time in Microsoft 

Excel, or spatial location was plotted in 

ArcGIS. UIC well and earthquake locations 

were mapped in relation to Oklahoma 

regional fault systems that were previously 

published as part of a study of the geologic 

provinces of Oklahoma (Northcutt and 

Campbell 1995), and for the Cherokee 

Platform geologic province by the Kansas 

Geological Survey (Nodine-Zeller and 

Thompson 1977).
Oklahoma Geological Survey OF1-2014

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3. Results and Discussion

Limited access to Osage County UIC 

well completion forms and annual fluid 

injection reports did not allow for 

confirmation of zones of injection and 

resulted in extreme overestimation of annual 

injection volumes. Because Osage County 

UIC well data have a greater degree of 

uncertainty, they were not critically 

analyzed or represented in all data tables or 

figures in this report.

In the Oklahoma UIC database, a well is 

referred to as ‘active’ if, for any given year, 

at least 1 bbl of water was reportedly 

injected. A query of the QAQC checked 

Oklahoma UIC database indicates that 8390, 

8265, 8738, and 8239 UIC wells were 

‘active’ from 2010–2013, respectively. Form 

1012As for the year 2011 were unavailable 

for at least 280 UIC wells or 3.3% and 3.2% 

of those that were active in 2010 and 2012, 

respectively. This data gap is believed to be 

due to Form 1012A submittals changing 

from hard-copy in 2010 to electronic in 

2011. Additional uncertainties and data gaps 

undoubtedly exist in the Oklahoma UIC 

database, for example, estimated 2D+2R 

water injection volumes for 2010 in 

Oklahoma (excluding Osage County) were 

reported as 1921 MMbbl in a 2013 paper 

(Murray 2013) but the estimated 2D+2R 

water injection volume for 2010 in 

Oklahoma (excluding Osage County) is 

1837 MMbbl in this report. Presumably 

additional QAQC will lead to more accurate 

future reports of injection volumes, 

pressures, and depths.

3.1. Highest Volume Class II UIC Wells

An injection rate exceeding 150,000 

BPM (i.e., 1.8 MMbbl per year) was 

selected to represent a ‘high volume UIC 

well’ because it was notable in the Barnett 

Shale region of Johnson County, Texas 

where 33.3% of the UIC wells exceeded this 

injection rate and potential induced 

seismicity was reported (Frohlich 2012). 

Oklahoma, excluding Osage County, had 

3297, 3221, 3507, and 3197 active 2D wells 

from 2010–2013, respectively, which are 

symbolized by relative annual injection 

volume in Figures 1–4. A small fraction, 

174 out of 3197 (5.44%) of the 2D wells 

shown in Figure 4 were high volume UIC 

wells during 2013. Oklahoma, excluding 

Osage County, had 5093, 5044, 5231, and 

5042 active 2R wells from 2010–2013, 

respectively, which are symbolized by 

relative annual injection volume in Figures 

5–8. Only 11 out of the 5042 (0.22%) active 

2R wells shown in Figure 8 were high 

volume UIC wells during 2013.

3.2. SWD Wells and Volumes by Geologic 

Zone of Completion

Oklahoma, excluding Osage County, had 

more than 3200 active SWD (i.e., 2D) wells 

from 2010–2013 (Table 1). The low number 

of active SWD wells during 2013 relative to 

2012 is because an estimated 296 annual 

fluid injection reports were not yet available 

from OCC.

Table 1 Number of active SWD (i.e., 2D) wells in

Oklahoma, by zone of completion

Zone

Active 

Wells 

in 2010

Active 

Wells 

in 2011

Active 

Wells 

in 2012

Active 

Wells 

in 2013

Permian 353 344 377 340

Virgilian 225 216 226 204

Missourian 286 268 280 259

Desmoinesian 618 567 602 537

AtokanMorrowan 281 265 264 230

Mississippian 126 126 124 109

Woodford 4 4 3 3

Dev to Mid

Ord 462 448 469 425

Arbuckle 477 537 667 667

Basement 7 8 11 10

MultipleUndiff 175 169 197 163

Other Or

Unspec 283 269 287 250

Total 3297 3221 3507 3197
Oklahoma Geological Survey OF1-2014

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Records of Class II UIC well volumes are

believed to be unreliable and incomplete

before the year 2009, so it is uncertain

whether present Class II UIC volumes

exceed historic Class II UIC volumes. For

example, much larger volumes of oil and gas

were produced in the 1980s and 1990s;

therefore, comparable volumes of water may

have been co-produced at that time.

Table 2 Volume of water injected into SWD (i.e., 2D)

wells in Oklahoma, by zone of completion

Zone

MMbbl 

H2O 

Injected 

in 2010

MMbbl 

H2O 

Injected 

in 2011

MMbbl 

H2O 

Injected 

in 2012

MMbbl 

H2O 

Injected 

in 2013

Permian 51.1 68.2 82.3 77.7

Virgilian 30.5 32.0 40.0 34.0

Missourian 26.5 24.7 27.0 29.1

Desmoinesian 34.1 33.3 34.7 30.7

AtokanMorrowan 46.8 46.7 52.3 46.4

Mississippian 9.3 9.5 9.4 7.9

Woodford 0.4 0.4 0.2 0.3

Dev to Mid

Ord 101.8 99.7 105.7 102.9

Arbuckle 449.2 523.1 568.2 739.1

Basement 0.8 0.6 1.4 0.7

MultipleUndiff 114.4 136.6 131.0 111.7

Other Or

Unspec 13.5 15.8 14.6 12.8

Total 878.3 990.8 1066.8 1193.3

Annual statewide 2D water injection 

volumes were 878.3, 990.8, 1066.8, and 

1193.3 MMbbl from 2010–2013, 

respectively (Table 2 and Figures 9–12). 

SWD (i.e., 2D) wells completed in the 

Arbuckle, predominantly carbonate, 

received the highest annual volumes of 

saltwater with 449.2, 523.1, 568.2, and 

739.1 MMbbl from 2010–2013, 

respectively, (Table 2 and Figures 9–12) 

which corresponds to a 289.9 MMbbl or 

64.5% increase from 2010 to 2013.

3.3. EORI Wells and Volumes by Geologic 

Zones of Completion

Oklahoma, excluding Osage County, had 

more than 5000 active EORI (i.e., 2R) wells 

from 2010–2013 (Table 3). The relatively 

low number of active wells for 2013 is 

because an estimated 165 EORI (i.e., 2R) 

well annual fluid injection reports were not 

yet available at OCC, assuming that those

reported in 2012 are still active.

Table 3 Number of active EORI (i.e., 2R) wells in

Oklahoma, by zone of completion

Zone

Active 

Wells 

in 2010

Active 

Wells 

in 2011

Active 

Wells 

in 2012

Active 

Wells 

in 2013

Permian 344 348 358 351

Virgilian 91 87 99 82

Missourian 1016 1004 1045 1021

Desmoinesian 1894 1854 1930 1883

AtokanMorrowan 692 713 725 692

Mississippian 130 131 129 125

Woodford 4 3 3 4

Dev to Mid

Ord 402 419 423 389

Arbuckle 20 23 22 21

Basement 0 0 1 1

MultipleUndiff 211 195 213 214

Other Or

Unspec 289 267 283 259

Total 5093 5044 5231 5042

Table 4 Volume of water injected into EORI (i.e., 2R)

wells in Oklahoma, by zone of completion

Zone

MMbbl 

H2O 

Injected 

in 2010

MMbbl 

H2O 

Injected 

in 2011

MMbbl 

H2O 

Injected 

in 2012

MMbbl 

H2O 

Injected 

in 2013

Permian 33.8 40.9 43.9 43.8

Virgilian 12.9 11.2 11.9 9.6

Missourian 226.1 234.5 269.1 253.0

Desmoinesian 283.0 290.4 296.9 295.0

AtokanMorrowan 155.4 168.6 181.5 172.9

Mississippian 37.5 38.4 36.4 34.9

Woodford 0.1 0.2 0.2 0.2

Dev to Mid

Ord 116.0 153.2 204.7 163.4
Oklahoma Geological Survey OF1-2014

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Arbuckle 10.4 14.9 14.7 14.2

Basement 0.0 0.0 0.0 0.0

MultipleUndiff 49.3 48.2 51.6 56.9

Other Or

Unspec 34.3 32.5 37.4 36.1

Total 958.8 1033.0 1148.5 1080.0

Oklahoma annual statewide, excluding 

Osage County, volume of EORI (i.e., 2R)

water injection was 958.8, 1033.0, 1148.5, 

and 1080.0 MMbbl from 2010–2013, 

respectively (Table 4 and Figures 9–12). 

EORI (i.e., 2R) wells completed in the 

Desmoinesian, comprised mostly of

sandstones, received the highest annual 

volumes of water with 283.0, 290.4, 296.9, 

and 295.0 MMbbl from 2010–2013, 

respectively (Table 4 and Figures 9–12).

3.4. Temporal Trends in SWD by County

Petroleum production, co-production of 

water, and SWD vary substantially in space 

and time; therefore, it is best to view trends 

on a smaller spatial scale (i.e., county-scale).

Table 5 SWD (i.e., 2D) volumes by county

County

MMbbl

of SWD 

in 2010

MMbbl

of SWD 

in 2011

MMbbl

of SWD 

in 2012

MMbbl

of SWD 

in 2013

Alfalfa 18.7 61.8 36.8 225.5

Beaver 3.0 5.5 8.3 13.0

Beckham 7.0 11.0 10.8 8.9

Blaine 4.3 8.6 6.6 3.5

Caddo 5.2 6.0 6.9 6.4

Canadian 6.3 7.7 10.1 9.6

Carter 9.1 9.6 11.3 12.4

Cleveland 1.3 1.2 1.1 0.6

Coal 11.3 7.9 6.7 3.8

Creek 46.4 37.7 44.2 28.9

Custer 0.5 1.4 4.3 3.3

Dewey 16.3 21.9 29.4 29.4

Ellis 3.0 5.8 7.3 10.4

Garfield 11.9 12.9 14.2 21.0

Garvin 9.8 12.7 16.3 14.9

Grady 2.2 3.3 3.9 3.7

Grant 8.2 24.2 19.6 54.2

Harper 4.4 3.4 3.1 2.7

Hughes 9.1 13.4 11.9 11.3

Kay 72.1 93.9 97.5 43.0

Kingfisher 5.7 6.4 5.4 7.7

Latimer 0.8 0.8 0.7 0.7

Le Flore 0.3 0.3 0.2 0.2

Lincoln 73.1 67.7 58.9 52.0

Logan 5.2 7.2 8.7 10.2

Love 0.3 0.3 0.3 0.3

McClain 1.6 2.3 3.5 4.0

McIntosh 3.2 3.5 2.6 1.6

Major 7.9 8.9 8.3 7.2

Murray 5.4 9.7 10.4 8.5

Muskogee 0.7 0.6 0.2 0.2

Noble 33.0 28.6 39.0 46.8

Nowata 0.8 0.5 0.8 2.0

Okfuskee 15.0 19.1 20.4 14.2

Oklahoma 61.8 65.8 74.8 67.2

Okmulgee 3.2 3.4 3.1 2.6

Pawnee 8.5 9.1 12.3 20.4

Payne 12.2 13.1 16.7 16.9

Pittsburg 1.4 2.2 4.3 3.1

Pontotoc 14.8 16.8 20.9 19.2

Pottawatomie 49.9 49.0 48.8 46.0

Roger Mills 6.5 13.1 14.3 6.3

Seminole 88.9 87.9 103.6 88.1

Stephens 5.1 5.1 5.7 3.9

Texas 2.1 2.2 3.9 4.4

Tillman 1.0 1.0 1.2 1.5

Tulsa 1.4 1.4 1.4 1.3

Wagoner 0.7 0.6 0.8 0.6

Washington 1.7 1.6 1.6 1.5

Washita 5.0 5.4 4.7 3.1

Woods 45.5 60.3 67.9 72.1

Woodward 7.2 7.2 5.8 3.2

Table 5 lists the 52 counties in Oklahoma 

that had a cumulative volume of ≥1 MMbbl 

water injected into Class II SWD wells from 

2010–2013. Reported annual volumes of 

SWD (i.e., 2D) increased for 28 out of the 

52 counties from 2010 to 2013. Annual and 

county-scale SWD volumes are also 

illustrated as charts on Figures 1–4. Alfalfa, 

Grant, and Woods Counties had the greatest 

increases of 206.8, 46.0, and 26.6 MMbbls, 

respectively.

3.5. Injection Depths and Pressures of SWD

SWD wells are designed to be cased, 

with steel and cement seals, below 

underground sources of drinking water 

(USDW). The injection interval is 

completed as open hole or the liner may be 

perforated within the target injection zone. 

Depths of injection intervals varied from 

356–18,886 ft below the land surface for 

active SWD (i.e., 2D) wells. The shallowest 

active SWD (i.e., 2D) well (named Jamison) 

injects into the Permian zone in Stephens
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County, Oklahoma to a depth of 356 ft. The 

deepest active SWD (i.e., 2D) well (named 

Tipton) injects into the Atokan-Morrowan 

zone in Roger Mills County, Oklahoma to a 

depth of 18,886 ft. SWD (i.e., 2D) wells 

completed in the ‘Other or Unspecified’ 

zone had the lowest median depth of 1785.5

ft, while SWD (i.e., 2D) wells completed in 

the Arbuckle zone had the deepest median 

depth of 6852 ft (shown in Figure 13).

Wellhead injection pressure for active 

SWD (i.e., 2D) wells in the Basement had 

the highest median value of 245 psi in 2010, 

while the Atokan-Morrowan, Dev to Mid 

Ord, and Arbuckle zone wells had a median 

injection pressure of <0 psi (Table 6 and 

Figures 14–17). Wellhead injection pressure 

data are of unknown quality because a large 

percentage of SWD (i.e., 2D) wells were 

reportedly operating on a vacuum, but were 

reported as injecting at 0 psi rather than <0 

psi.

Table 6 Median wellhead pressures reported for active

SWD (i.e., 2D) wells, by completion zone

Zone

Median 

psi in 

2010

Median 

psi in 

2011

Median 

psi in 

2012

Median 

psi in 

2013

Permian 188 200 171 167

Virgilian 200 200 200 216

Missourian 125 120 117 105

Desmoinesian 100 100 91 82

AtokanMorrowan 10 0 0 0

Mississippian 50 50 50 50

Woodford 11 20 40 40

Dev to Mid

Ord 0 0 0 10

Arbuckle 0 0 0 5

Basement 245 186 100 231

MultipleUndiff 150 150 125 135

Other Or

Unspec 50 50 50 50

3.6. Temporal Trends in EORI by County

Secondary oil production can be realized 

using enhanced oil recovery (EOR), 

whereby fluids (e.g., H2O or CO2) are 

injected into an EORI well. ‘Water flooding’ 

is a common practice in several Oklahoma 

counties. Table 7 lists the 38 counties in 

Oklahoma that had a cumulative volume of 

≥1 MMbbl water injected into EORI wells 

from 2010–2013. Reported annual water 

(e.g., brackish or saltwater) volumes of 

EORI (i.e., 2R) increased for 23 out of the 

38 counties from 2010 to 2013. Pontotoc, 

Carter, and Garvin Counties had the greatest 

increases of 37.9, 14.8, and 9.8 MMbbls, 

respectively.

Table 7 EORI (i.e., 2R) volumes by county

County

MMbbl

of EORI

in 2010

MMbbl

of EORI 

in 2011

MMbbl

of EORI

in 2012

MMbbl

of EORI

in 2013

Alfalfa 0.6 0.9 0.9 1.0

Beaver 6.0 6.6 6.1 6.8

Bryan 0.2 0.2 0.3 0.3

Caddo 7.4 7.9 8.0 9.4

Carter 241.2 247.5 274.5 256.0

Cimarron 0.2 0.3 0.3 0.3

Cleveland 0.4 0.4 0.4 0.1

Cotton 0.5 0.5 0.6 0.5

Creek 69.8 73.0 76.5 71.7

Dewey 15.0 14.6 15.0 14.1

Garfield 0.3 0.3 0.4 0.4

Garvin 26.0 32.8 34.3 35.8

Grady 10.2 11.3 12.2 9.9

Grant 3.7 3.1 4.0 2.7

Jefferson 1.0 1.0 1.8 1.1

Kay 6.6 7.1 7.2 6.0

Lincoln 7.2 7.9 6.2 5.7

Logan 0.2 0.2 0.3 0.3

Love 0.3 0.3 0.3 0.3

McClain 0.7 2.2 0.2 0.0

Murray 4.1 10.4 12.0 11.4

Muskogee 0.4 0.3 0.4 0.1

Noble 1.2 1.2 1.3 1.5

Nowata 13.6 13.7 13.2 13.5

Okfuskee 3.0 4.5 5.5 5.1

Oklahoma 4.0 4.0 5.2 5.7

Okmulgee 0.9 0.9 0.4 1.4

Pawnee 3.9 3.7 4.1 4.6

Payne 0.9 0.9 0.9 0.8

Pittsburg 0.5 0.7 0.7 0.5

Pontotoc 79.4 108.3 156.6 117.2

Pottawatomie 3.2 4.3 3.7 3.6

Seminole 26.7 27.5 28.7 26.5

Stephens 42.3 47.2 51.1 45.7

Texas 34.3 34.6 36.3 40.0

Wagoner 0.2 0.2 0.3 0.4

Woods 4.9 5.1 5.7 3.8

Woodward 7.1 7.7 7.2 7.0
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3.7. Seismic Activity in Oklahoma

Seismic activity has increased 

significantly in recent years, with about 109 

magnitude 3.0 or greater earthquakes 

occurring in 2013 and more than 500 

magnitude 3.0 or greater earthquakes 

occurring in 2014 (OGS 2014). From 2010-

2012, the majority of earthquakes were 

located in central Oklahoma (Figures 18–

20), but numerous earthquakes occurred in 

Grant, Alfalfa, and Woods Counties of 

north-central Oklahoma during 2013 (Figure 

21). Median depth for earthquakes (i.e., 

focal depth or origin) in Oklahoma was 

about 12,303 ft (~3.75 km), and more than 

75% of focal points were at depths of more 

than 9842 ft (~2.5 km), as shown in Figure 

22.

Because SWD (i.e., 2D) wells injecting 

into the Arbuckle zone are in direct contact 

with or close proximity to basement rock, 

they may be the most relevant for 

comparison to seismic activity, which is 

typically focused on basement fault 

networks (Zhang et al. 2013). Changes in 

seismicity were observed in numerous

counties of Oklahoma having active Class II 

SWD wells completed in the Arbuckle or 

Basement zones. A spatiotemporal 

comparison was made between change in 

SWD volumes into the Arbuckle or 

Basement zones (2013 & 2012 versus 2011 

& 2010) and change in seismicity (2013 & 

2012 versus 2011 & 2010) at a county-scale. 

These data were organized into four 

quadrants on Figure 23, whereby Quad A 

includes counties (e.g., Oklahoma) with an 

increase in SWD (+SWD) and a decrease in 

number of earthquakes (-EQ), Quad B 

includes counties (e.g., Grant and Alfalfa) 

with an increase in SWD (+SWD) and an 

increase in number of earthquakes (+EQ), 

Quad C includes counties (e.g., Lincoln) 

with a decrase in SWD (-SWD) and an 

increase in number of earthquakes (+EQ), 

and Quad D includes counties (e.g., Garvin) 

with a decrease in SWD (-SWD) and a 

decrease in number of earthquakes (-EQ)

from 2010–2013. Those counties (e.g., 

Alfalfa, Coal, Garvin, Grant, Kay, Lincoln, 

Oklahoma, Payne, Seminole, and Woods) 

that deviate substantially from the origin in 

Figure 23 would be interesting for more 

detailed studies of geologic factors that may 

affect seismicity.

4. Future Directions

Measurement of pre-injection hydraulic 

conditions and formation pressure, along 

with increased temporal resolution of 

injection rates and pressures are critical for 

understanding the dynamic relationships 

between fluid injection and seismicity 

(Ellsworth 2013). Thorough evaluation of 

the presence or absence of faulting near 

fluid-injection wells (Frohlich 2012) is also 

a priority for understanding potential for 

induced seismicity.

Reasonable estimates of field-scale 

historic and future fluid-injection and 

withdrawal volumes must be made for all 

production or injection zones so that 

production versus injection versus seismicity 

can be put into the proper perspective. 

Integrated hydrogeologic, structural 

geologic, and seismologic datasets may then 

be evaluated to establish mechanisms by 

which fluid injection affects pore pressure 

along a fault plane.

These integrated scientific studies could 

be useful for the development of adaptable 

regulatory requirements and bestmanagement practices for Class II wells 

managed in the underground injection 

control program.

5. References

Boyd DT (2008) Stratigraphic Guide to 

Oklahoma Oil and Gas Reservoirs. 

Oklahoma Geological Survey, 

SP2008-1. Norman, OK. pp. 2.

Davis SD, Pennington WD (1989) Induced 

seismic deformation in the Cogdell 
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oil field of west Texas. Bulletin of 

the Seismological Society of 

America 79:1477-1495

EIA (2014a) Field Production of Crude Oil 

in the United States. 

http://www.eia.gov/dnav/pet/pet_crd

_crpdn_adc_mbbl_a.htm. Cited Jul 

22 

EIA (2014b) Natural Gas Gross 

Withdrawals and Production. 

http://www.eia.gov/dnav/ng/ng_prod

_sum_dcu_nus_m.htm. Cited Jul 1 

Ellsworth WL (2013) Injection-Induced 

Earthquakes. Science 341:142-149 

DOI 10.1126/science.1225942

Frohlich C (2012) Two-year survey 

comparing earthquake activity and 

injection-well locations in the 

Barnett Shale, Texas. Proceedings of 

the National Academy of Sciences 

109:13934-13938 DOI 

10.1073/pnas.1207728109

Healy JH, Rubey WW, Griggs DT, Raleigh 

CB (1968) The Denver Earthquakes. 

Science 161:1301-1310 DOI 

10.2307/1725684

Holland AA (2013) Earthquakes Triggered 

by Hydraulic Fracturing in SouthCentral Oklahoma. Bulletin of the 

Seismological Society of America 

103:1784-1792 DOI 

10.1785/0120120109

Horton S (2012) Disposal of Hydrofracking 

Waste Fluid by Injection into 

Subsurface Aquifers Triggers 

Earthquake Swarm in Central 

Arkansas with Potential for 

Damaging Earthquake. 

Seismological Research Letters 

83:250-260 DOI 

10.1785/gssrl.83.2.250

Keranen KM, Savage HM, Abers GA, 

Cochran ES (2013) Potentially 

induced earthquakes in Oklahoma, 

USA: Links between wastewater 

injection and the 2011 Mw 5.7 

earthquake sequence. Geology 

41:699-702 DOI 10.1130/g34045.1

Lord C (2012) Monthly injection volumes 

for Class II Underground Injection 

Control (UIC) wells in Oklahoma, 

2011. In: Oil and Gas Division, 

Oklahoma Corporation Commission, 

Oklahoma City, OK.

Lord C (2014) Monthly injection volumes 

for Class II Underground Injection 

Control (UIC) wells in Oklahoma. 

In: Oil and Gas Division, Oklahoma 

Corporation Commission, Oklahoma 

City, OK.

Murray KE (2013) State-Scale Perspective 

on Water Use and Production 

Associated with Oil and Gas 

Operations, Oklahoma, U.S. Environ 

Sci Technol 47:4918-4925 DOI 

10.1021/es4000593

Murray KE, Holland AA (2014) Inventory 

of Class II Underground Injection 

Control Volumes in the 

Midcontinent. Shale Shaker 65:98-

106

Nicholson C, Wesson RL (1990) Earthquake 

hazard associated with deep well 

injection-A report to the U.S. 

Environmental Protection Agency. 

US Geological Survey Bulletin 1951. 

pp. 74.

Nodine-Zeller DE, Thompson TL (1977) 

Age and structure of subsurface beds 

in Cherokee County, Kansas: 

Implications from endthyrid 

foraminifera and conodonts. Kansas 

Geological Survey, Lawrence, KS

Northcutt RA, Campbell JA (1995) 

Geologic provinces of Oklahoma. 

Oklahoma Geological Survey OpenFile Report (OF5-95) 

NRC (2012) Induced Seismicity Potential in 

Energy Technologies. National 

Academy of Sciences, Washington, 

DC
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OCC (2014a) UIC Injection Volumes 2012. 

http://www.occeweb.com/og/ogdataf

iles2.htm. Cited Nov 25 

OCC (2014b) UIC Injection Volumes 2013. 

http://www.occeweb.com/og/ogdataf

iles2.htm. Cited Nov 25 

OCC (2014c) Well Data System. 

http://www.occpermit.com/WellBro

wse/Home.aspx. Cited various dates 

OGS (2014) Leonard Geophysical 

Observatory Catalog. 

http://www.okgeosurvey1.gov/pages/

earthquakes/catalogs.php. Cited 1 

Sep 2014

Raleigh CB, Healy JH, Bredehoeft JD 

(1976) An experiment in earthquake 

control at Rangely, Colorado. 

Science 191:1230-1237

Zhang Y, Person M, Rupp J, Ellett K, Celia 

MA, Gable CW, Bowen B, Evans J, 

Bandilla K, Mozley P, Dewers T, 

Elliot T (2013) Hydrogeologic 

Controls on Induced Seismicity in 

Crystalline Basement Rocks Due to 

Fluid Injection into Basal Reservoirs. 

Ground Water 51:525-538 DOI 

10.1111/gwat.12071

Abbreviations, Units, and Definitions

2D: Class II Disposal (aka SWD)

2R: Class II Recovery (aka EORI)

API: American Petroleum Institute

bbl: barrels

BIA: Bureau of Indian Affairs

BPD: Barrels Per Day

BPM: Barrels Per Month

BWPM: Barrels of Water Per Month

CO2: carbon dioxide

EOR: Enhanced Oil Recovery

EORI: Enhanced Oil Recovery Injection

(aka 2R)

EPA: Environmental Protection Agency

high volume UIC well: exceeding 150,000

BWPM or 1.8 MMbbl per year

LPG: Liquefied Petroleum Gas

MCF: thousand cubic feet

MMbbl: Millions of barrels

OCC: Oklahoma Corporation Commission

OGS: Oklahoma Geological Survey

psi: pounds per square inch

SWD: SaltWater Disposal (aka 2D)

QAQC: Quality Assurance Quality Control

UIC: Underground Injection Control

USDW:Underground Sources of Drinking

Water
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Figure 1 Map of SWD wells and relative volumes of water injected into SWD Class II UIC wells (i.e., 2D) during 2010. Chart of SWD well volumes in 2010 by county.
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Figure 2 Map of SWD wells and relative volumes of water injected into SWD Class II UIC wells (i.e., 2D) during 2011. Chart of SWD well volumes in 2011 by county.
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Figure 3 Map of SWD wells and relative volumes of water injected into SWD Class II UIC wells (i.e., 2D) during 2012. Chart of SWD well volumes in 2012 by county.
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Figure 4 Map of SWD wells and relative volumes of water injected into SWD Class II UIC wells (i.e., 2D) during 2013. Chart of SWD well volumes in 2013 by county.
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Figure 5 Map of EORI wells and relative volumes of water injected into EORI Class II UIC wells (i.e., 2R) during 2010. Chart of EORI well volumes in 2010 by county.
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Figure 6 Map of EORI wells and relative volumes of water injected into EORI Class II UIC wells (i.e., 2R) during 2011. Chart of EORI well volumes in 2011 by county.
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Figure 7 Map of EORI wells and relative volumes of water injected into EORI Class II UIC wells (i.e., 2R) during 2012. Chart of EORI well volumes in 2012 by county.
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Figure 8 Map of EORI wells and relative volumes of water injected into EORI Class II UIC wells (i.e., 2R) during 2013. Chart of EORI well volumes in 2013 by county.
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Figure 9 Chart of UIC well volumes in 2010 by geologic zone of completion.
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Figure 10 Chart of UIC well volumes in 2011 by geologic zone of completion.
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Figure 11 Chart of UIC well volumes in 2012 by geologic zone of completion.
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Figure 12 Chart of UIC well volumes in 2013 by geologic zone of completion.
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Figure 13 Depths, below land surface, for completion intervals of 2010–2013 active SWD (i.e., 2D) wells in Oklahoma
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Figure 14 Wellhead injection pressure (psi) for active SWD (i.e., 2D) wells in 2010

Figure 15 Wellhead injection pressure (psi) for active SWD (i.e., 2D) wells in 2011
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Figure 16 Wellhead injection pressure (psi) for active SWD (i.e., 2D) wells in 2012

Figure 17 Wellhead injection pressure (psi) for active SWD (i.e., 2D) wells in 2013
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Figure 18 Map of earthquakes and relative magnitudes during 2010, data from OGS earthquake catalog. Chart of >=3.0 magnitude earthquakes in 2010 by month.
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Figure 19 Map of earthquakes and relative magnitudes during 2011, data from OGS earthquake catalog. Chart of >=3.0 magnitude earthquakes in 2011 by month.
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Figure 20 Map of earthquakes and relative magnitudes during 2012, data from OGS earthquake catalog. Chart of >=3.0 magnitude earthquakes in 2012 by month.
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Figure 21 Map of earthquakes and relative magnitudes during 2013, data from OGS earthquake catalog. Chart of >=3.0 magnitude earthquakes in 2013 by month.
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Figure 22 Number of earthquakes versus depth of focal point for 2000–2013
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Figure 23 Spatiotemporal comparison of change in SWD versus change in seismicity at a county-scale