Estimated Oil and Gas Reserves

Gulf of Mexico

December 31, 2005

Outer Continental Shelf

U.S. Department of the Interior

Minerals Management Service MMS Gulf of Mexico OCS Region

OCS Report

MMS 2009-022

 OCS Report 

 MMS 2009-022 

Outer Continental Shelf

Estimated Oil and Gas Reserves 

Gulf of Mexico 

December 31, 2005 

 

Authors 

T. Gerald Crawford 

Grant L. Burgess 

Steven M. Haley 

Peter F. Harrison 

Clark J. Kinler 

Gregory D. Klocek 

Nancy K. Shepard 

Resource Evaluation Office 

Reserves Section 

 Published by

U.S. Department of the Interior

Minerals Management Service New Orleans 

Gulf of Mexico OCS Regional Office May 2009 
ii
iii

Contents

Abstract v 

Introduction 1 

Definition of Resource and Reserve Terms 1 

Reference Standard Conditions for Production and Reserves 4 

MMS Reporting of Reserve and Resource Data 4 

Methods Used for Estimating Reserves 5 

Reserves and Related Data Reported by Area 6 

Reserves Reported by Geologic Age 12 

Historical Exploration and Discovery Pattern and Trends 19 

Field-Size Distribution 24 

Reservoir-Size Distribution 34 

Production Rates and Discovery Trends 36 

Summary and Comparison of Proved Reserves 44 

Conclusions 46 

Contributing Personnel 46 

References 47 

Figures 

 1. MMS conventionally recoverable petroleum resource classifications 1 

 2. Gulf of Mexico MMS reserve classifications 2 

 3. MMS evaluation of reserves and resources 4 

 4. Western Planning Area, Gulf of Mexico, Outer Continental Shelf 6 

 5. Central Planning Area, Gulf of Mexico, Outer Continental Shelf 7 

 6. Eastern Planning Area, Gulf of Mexico, Outer Continental Shelf 7 

 7. Gulf of Mexico, 1,196 proved fields (951 active and 245 depleted) 9 

 8. Gulf of Mexico, 56 unproved active fields 9 

 9. Gulf of Mexico MMS geologic time scale 11 

 10. Pleistocene reserves trend 14 

 11. Pliocene reserves trend 14 

 12. Miocene reserves trend 17 

 13. Pre-Miocene reserves trend 17 

 14. Distribution of reserves and production data by geologic age 18 

 15. Location of proved fields discovered 1947-1959, Gulf of Mexico OCS 19 

 16. Location of proved fields discovered 1960-1969, Gulf of Mexico OCS 20 

 17. Location of proved fields discovered 1970-1979, Gulf of Mexico OCS 21 

 18. Location of proved fields discovered 1980-1989, Gulf of Mexico OCS 21 

 19. Location of proved fields discovered 1990-1999, Gulf of Mexico OCS 22 

 20. Location of proved fields discovered 2000-2005, Gulf of Mexico OCS 22 

 21. Annual number of field discoveries by geologic age, 1,196 proved fields 23 

 22. Annual discoveries of proved reserves by geologic age, 1,196 proved fields 24 

 23. Description of deposit-size classes 25 

 24. Field-size distribution of proved fields: (a) 1,196 fields, GOM; (b) 335 fields, 

Western GOM; (c) 861 fields, Central and Eastern GOM 26 

 25. Field-size distribution of proved oil fields: (a) 223 fields, GOM; (b) 30 fields, 

Western GOM; (c) 193 fields, Central and Eastern GOM 27 

 26. Field-size distribution of proved gas fields: (a) 973 fields, GOM; (b) 305 fields, 

Western GOM; (c) 668 fields, Central and Eastern GOM 28 
iv

 

 27. Field-size distribution of unproved fields: (a) 56 fields, GOM; (b) 32 oil fields, GOM; 

(c) 24 gas fields, GOM 29 

 28. GOM field-size distribution 30 

 29. Cumulative percent total reserves versus rank order of field size for 1,196 proved fields 31 

 30. Field and reserves distribution by water depth 31 

 31. Largest 20 fields ranked by remaining proved reserves 32 

 32. Reservoir-size distribution, 2,223 proved combination reservoirs 34 

 33. Reservoir-size distribution, 7,906 proved oil reservoirs 35 

 34. Reservoir-size distribution, 17,003 proved gas reservoirs 35 

 35. Monthly distribution of oil production, 2,316 completions, (1,394 continuously 

producing completions) 36 

 36. Monthly distribution of gas production, 2,503 completions, (1,529 continuously 

producing completions) 37 

 37. Monthly completion and production data 37 

 38. Annual oil and gas production 38 

 39. Proved reserves and production by field discovery year 39 

 40. Annual number of proved oil and gas field discoveries 39 

 41. Number of proved fields and mean field size by field discovery year 41 

 42. Number of proved and unproved fields and mean water depth by field discovery year 41 

 43. Proved oil reserves by reservoir discovery year and annual oil production 42 

 44. Proved gas reserves by reservoir discovery year and annual gas production 42 

 45. Wells and footage drilled 43 

 46. Number of exploratory wells drilled by water depth 43 

Tables 

 1. Estimated oil and gas reserves for 1,196 proved and 56 unproved fields by area, 

Gulf of Mexico, Outer Continental Shelf, December 31, 2005 8 

 2. Status of oil and gas leases, boreholes, and completions by area, Gulf of Mexico, 

Outer Continental Shelf, December 31, 2005 10 

 3. Estimated oil and gas reserves for 1,196 proved and 56 unproved fields by geologic 

age, Gulf of Mexico, Outer Continental Shelf, December 31, 2005 12 

 3a. Estimated oil and gas reserves for Pleistocene reservoirs in 397 proved and 10 

unproved fields by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005 13 

 3b. Estimated oil and gas reserves for Pliocene reservoirs in 533 proved and 21 unproved 

fields by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005 15 

 3c. Estimated oil and gas reserves for Miocene reservoirs in 709 proved and 18 unproved 

fields by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005 16 

 3d. Estimated oil and gas reserves for Pre-Miocene reservoirs in 23 proved and 3 unproved 

fields by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005 16 

 3e. Estimated oil and gas reserves for reservoirs that Span Ages in 5 proved and 16 unproved 

 fields by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005 18 

 4. Gulf of Mexico proved fields by rank order, based on proved BOE reserves, top 50 fields 33 

 5. Summary and comparison of proved oil and gas reserves as of December 31, 2004, 

 and December 31, 2005 44 

 6. Proved oil and gas reserves and cumulative production at end of year, 1975-2005, 

Gulf of Mexico Outer Continental Shelf and Slope 45 
v

Abstract

As of December 31, 2005, proved reserves in the Gulf of Mexico Outer Continental Shelf 

(OCS) are estimated to be 19.80 billion barrels of oil and 181.8 trillion cubic feet of gas from 

1,196 proved fields. Proved reserves are the total of the cumulative production plus 

remaining proved reserves. This number includes 24 proved fields that were added during 

2005. It also includes the 245 proved fields that have produced and expired. It does not 

include the 56 unproved active fields. Estimates are derived for individual reservoirs from 

geologic mapping and reserve evaluation. Cumulative production from the proved fields 

accounts for 14.61 billion barrels of oil and 163.9 trillion cubic feet of gas. Remaining proved 

reserves are estimated to be 5.19 billion barrels of oil and 17.9 trillion cubic feet of gas. 

These reserves are recoverable from 951 proved active fields. 

Unproved reserves are estimated to be 3.23 billion barrels of oil and 8.4 trillion cubic feet of 

gas. These reserves are associated with the 56 unproved active fields studied and the 

unproved reserves in proved fields. In total, there are 1,007 proved and unproved active 

fields located in Federal waters. The unproved reserves, associated with the proved and 

unproved active fields studied, are not added to proved reserves because of different levels 

of economic certainty and hydrocarbon assurance. For any field spanning State and Federal 

waters, reserves are estimated for the Federal portion only. 

In addition to the proved and unproved reserves discussed above, there are 1.38 billion 

barrels of oil and 7.6 trillion cubic feet of gas that are not presented in the tables and figures 

of this report. This oil and gas occurs on leases that have not yet qualified (and therefore 

have not been placed in a field) or they occur as known resources in proved fields, or as 

known resources in unproved fields. As further drilling and development occur, additional 

hydrocarbon volumes will become reportable, and MMS anticipates future proved and 

unproved reserves to increase. 

 

43.77 (BBOE)

 2.72 (BBOE)

 4.72 (BBOE)

 8.38 (BBOE)

Cumulative Production

Remaining Proved Reserves

Unproved Reserves

Total Not Presented

5%

73%

8%

14%

14.61 Bbbl - Oil

163.9 Tcf - Gas

5.19 Bbbl - Oil

17.9 Tcf - Gas

3.23 Bbbl - Oil

 8.4 Tcf - Gas

1.38 Bbbl - Oil

 7.6 Tcf - Gas

Gulf of Mexico Reserves and Resources
vi
1

Introduction

This report, which supersedes the Minerals Management Service (MMS) OCS Report MMS 2008-034 (Crawford and 

others, 2008), presents estimated proved reserves, cumulative production, remaining proved reserves, and unproved 

reserves as of December 31, 2005, for the Gulf of Mexico (GOM). Reserves growth (an observed phenomenon that 

occurs when there is an incremental increase through time in the estimates of proved reserves) and undiscovered 

and known resources are not addressed in this report. A discussion of reserves growth can be found in OCS Report 

MMS 2001-0087 (Lore and others, 2001). The estimates of reserves for this report were completed in December 

2008 and represent the combined efforts of engineers, geologists, geophysicists, paleontologists, and other personnel 

of the MMS Gulf of Mexico Region, Office of Resource Evaluation, in New Orleans, Louisiana. 

As in previous reports, standard methods of estimating reserves were used, including volumetric calculations and 

performance analyses. 

Definition of Resource and Reserve Terms

The MMS definitions and classification schema concerning reserves reflect those of the Society of Petroleum 

Engineers (SPE) and the World Petroleum Congress (WPC), 1996. SPE definitions have been used since 1988. 

The MMS definitions and classification schema concerning resources are modified as referenced by the U.S. 

Department of the Interior, 1989. The MMS petroleum resource and reserve classifications are presented in Figures 

1 and 2. 

(Modified from U.S. Bureau of Mines and U.S. Geological Survey, 1980)

Increasing Hydrocarbon Assurance

Increasing Economic Certainty

Undiscovered Resources 

Proved Reserves

Not Within

Known 

Fields

Known

Resources

Possible Probable Undeveloped Developed

Nonproducing Economically 

Recoverable

Uneconomic

Producing

Discovered Resources

Unproved

Reserves

Undrilled Prospects Drilled Prospects

Within 

Known 

Fields

Not Within

Known 

Fields

Within Known Fields

Undiscovered 

Conventionally

Recoverable Resources

Figure 1. MMS conventionally recoverable petroleum resource classifications.
2

Unproved

Possible

Reserves

Proved

Undeveloped

Reserves

Increasing Hydrocarbon Assurance and Economic Certainty

Known

Resources

Proved

Developed

Reserves

Unproved

Probable

Reserves

Discovery on 

Active Lease

Development

Plan

Development

Expenditure

Production and

Transportation

Equipment

Installed

Unproved Reserves Proved Reserves

Lease Expiration

Undiscovered

Conventionally

Recoverable

Resources

Geologic

Evidence

of Existence

Figure 2. Gulf of Mexico MMS reserve classifications.

Field 

A field is an area consisting of a single reservoir or multiple reservoirs all grouped on, or related to, the same general 

geologic structural feature and/or stratigraphic trapping condition. There may be two or more reservoirs in a field that 

are separated vertically by impervious strata, laterally by local geologic barriers, or by both. The area may include 

one OCS lease, a portion of an OCS lease, or a group of OCS leases with one or more wells that have been 

approved as producible by the MMS pursuant to the requirements of Title 30 Code of Federal Regulations (CFR) 

250.115/116, Determination of Well Producibility. A field is usually named after the area and block on which the 

discovery well is located. Field names or field boundaries may be changed when additional geologic and/or 

production data initiate such a change. Using geological criteria, the MMS designates a new producible lease as a 

new field or assigns it to an existing field. A further explanation of field naming convention can be found in the 

“Reserves and Related Data Reported by Area” section on page 6 and in the Field Naming Handbook available from 

MMS’s Gulf of Mexico Region Internet Web site at http://www.gomr.mms.gov. 

 

Resources 

Concentrations of naturally occurring liquid or gaseous hydrocarbons that can conceivably be discovered and 

recovered are called resources. Normal use encompasses both undiscovered and discovered resources. 

Undiscovered Resources

Hydrocarbons estimated on the basis of geologic knowledge and theory to exist outside of known accumulations 

are undiscovered resources. Undiscovered resources analogous to those in existing fields producible with current 

recovery technology and efficiency, but without any consideration of economic viability, are undiscovered 

conventionally recoverable resources. 

Discovered Resources 

Hydrocarbons whose location and quantity are known or estimated from specific geologic evidence are discovered 

resources. Discovered resources include known resources, unproved reserves, and proved reserves depending 

upon economic, technical, contractual, or regulatory criteria. 

Known Resources

Hydrocarbons associated with reservoirs penetrated by one or more wells that are on leases that are active, 

expired, relinquished, or terminated are identified as known resources. 
3

Reserves

Those quantities of hydrocarbons which are anticipated to be recovered from known accumulations from a given date 

forward are reserves. All reserve estimates involve some degree of uncertainty. The uncertainty depends chiefly on 

the amount of reliable geologic and engineering data available at the time of the estimate and the interpretation of 

these data. The relative degree of uncertainty may be conveyed by placing reserves into one of two principal 

classifications, either unproved or proved. 

Unproved Reserves

Those quantities of hydrocarbons that can be estimated with some certainty to be potentially recoverable from 

known reservoirs, assuming future economic conditions and technological developments, are unproved reserves. 

The MMS Gulf of Mexico Regional Field Names Committee designates a new producible lease as a new field or 

assigns it to an existing field. The reserves associated with new producible leases qualified pursuant to 30 CFR 

250.115/116 are initially considered unproved reserves. Unproved reserves are less certain to be recovered than 

proved reserves and are further subclassified as possible and probable reserves to denote progressively 

increasing certainty in their recoverability. This report does not present individual estimates for possible and 

probable reserves. 

Unproved possible reserves are those unproved reserves which analysis of geological and engineering 

data suggests are less likely to be commercially recoverable than probable reserves. After a well on a lease 

qualifies, the reserves associated with the lease are initially classified as unproved possible because the only 

direct evidence of economic accumulations is a production test or electric log analysis. 

Unproved probable reserves are those unproved reserves which analysis of geological and engineering 

data suggests are more likely than not to be commercially recoverable. Fields that have a Development 

Operations Coordination Document (DOCD) on file with the MMS would be classified as unproved probable. 

Proved Reserves

Those quantities of hydrocarbons which can be estimated with reasonable certainty to be commercially 

recoverable from known reservoirs under current economic conditions, operating methods, and government 

regulations are proved reserves. Establishment of current economic conditions includes consideration of 

relevant historical petroleum prices and associated costs and may involve an averaging period that is consistent 

with the purpose of the reserve estimate. Proved reserves must have either facilities operational at the time of 

the estimate to process and transport those reserves to market, or a commitment or reasonable expectation to 

install such facilities in the future. The application for a permit to install a platform is considered such a 

commitment. Proved reserves can be subdivided into undeveloped or developed. 

Proved undeveloped reserves exist where there is a relatively large expenditure required to install 

production and/or transportation facilities and a commitment has been made by the operator to develop the 

field. Proved undeveloped reserves are reserves expected to be recovered from planned development wells 

or from existing wells where a relatively large expenditure is required for field development. 

Proved developed reserves are expected to be recovered from existing wells (including reserves behind 

pipe). Reserves are considered developed only after the necessary production and transportation equipment 

has been installed, or when the costs to do so are relatively minor. Proved developed reserves are 

subcategorized as producing or nonproducing. This distinction is made at the reservoir level. 

Proved Developed Producing Reserves are in reservoirs that have produced any time during the 12 

months before the reporting date. Once the first reservoir in a field begins production, the reservoir and 

the field are considered proved developed producing. 

Proved Developed Nonproducing Reserves are in reservoirs that have not produced during the 12 months 

prior to the reporting date. This category includes off-production reservoirs behind pipe and reservoirs 

awaiting workovers or transportation facilities. If all reservoirs in a field are off production, the field is 

considered proved developed nonproducing. 

Remaining proved reserves are the quantities of proved reserves currently estimated to be recoverable. 

Estimates of remaining proved reserves equal proved reserves minus cumulative production. 
4

Reference Standard Conditions for Production and Reserves

Production data are the metered volumes of raw liquids and gas reported to the MMS by Federal unit and lease 

operators. Oil volume measurements and reserves are corrected to reference standard conditions of 60°F and one 

atmosphere (14.696 pounds per square inch absolute [psia]); gas measurements and reserves are corrected to 60°F 

and 15.025 psia. To convert gas volumes to 14.696 psia, multiply by 1.022 (DOE, 1989). Continuously measured 

volumes from production platforms and/or leases are allocated to individual wells and reservoirs on the basis of 

periodic well test gauges. These procedures introduce approximations in both production and remaining reserves 

data. 

MMS Reporting of Reserve and Resource Data 

OCS reserve estimates have been published by the Gulf of Mexico Region annually since 1977, presenting end-ofyear totals starting with 1975. From 1977 to 1981, the estimates were published as United States Geological Survey 

(USGS) Open-File reports. The 1982 report was a joint publication between the USGS and the newly formed MMS, 

which assumed the OCS mission responsibilities at that time. The MMS has continued the reporting since 1983. The 

first report provided by MMS that also includes unproved reserve estimates was published in 1995. 

Figure 3 shows the relationship of evaluated data to hydrocarbon assurance. The data are progressively aggregated 

on both a geologic and a geographic basis at each step of the evaluation process (the reservoir level through the 

region level). The most detailed studies of discovered resources are MMS individual field studies. These studies are 

based on analysis at the reservoir level (an example being a single fault trap in a single sand) and are used as the 

basis for the reporting of discovered and undiscovered resources. The geologic aggregation begins at the top of the 

figure at the reservoir level and progresses downward through the sand, pool, play, chronozone, series, and system 

to the region level. Reservoirs associated with a specific sand are aggregated to form the sand reporting level, which 

becomes the basis for further aggregations of data. A play is defined primarily (though not exclusively) by 

depositional style, geologic age at the chronozone level, and geographic area. Pools are based on the same 

characteristics as a play, but are specific to an individual field. Fields may contain one or more pools, with each pool 

representing a separate play. The geographic aggregation begins at the bottom of the figure, also at the reservoir 

level, and progresses upward through the field, area, and planning area to the region level. 

Offshore Atlas National

Assessm ent 

Estim ated Oil and Gas 

Reserves 

M M S Internal Field 

Studies

Reporting /

Evaluation

Level

Undiscovered Resources Discovered Resources 

Proved

Reserves

Unproved

Reserves

Undiscovered 

Conventionally 

Recoverable 

Resources

Known

Resources

Increasing Hydrocarbon Assurance and Econom ic Certainty

Progressively

aggregated

Geographically

Progressively

aggregated

Geologically

Reservoir

Sand

Pool

Play

Chronozone

Area

Field

Reservoir

Series

System

Region

Planning Area

Undrilled Prospects Drilled Prospects 

Known

Resources

W ithin Know n Fields Not W ithin Know n 

Fields

Not W ithin Know n 

Fields

W ithin Know n Fields

Undiscovered 

Conventionally 

Recoverable 

Resources

Province

Offshore Atlas National

Assessm ent 

Estim ated Oil and Gas 

Reserves 

M M S Internal Field 

Studies

Reporting /

Evaluation

Level

Undiscovered Resources Discovered Resources 

Proved

Reserves

Unproved

Reserves

Undiscovered 

Conventionally 

Recoverable 

Resources

Known

Resources

Increasing Hydrocarbon Assurance and Econom ic Certainty

Progressively

aggregated

Geographically

Progressively

aggregated

Geologically

Reservoir

Sand

Pool

Play

Chronozone

Area

Field

Reservoir

Series

System

Region

Planning Area

Undrilled Prospects Drilled Prospects 

Known

Resources

W ithin Know n Fields Not W ithin Know n 

Fields

Not W ithin Know n 

Fields

W ithin Know n Fields

Undiscovered 

Conventionally 

Recoverable 

Resources

Province

Figure 3. MMS evaluation of reserves and resources. 
5

This report, Estimated Oil and Gas Reserves, presents reserve data for the field level through the series level (see 

Figure 3). This report is based on aggregation of MMS internal field studies completed at the reservoir and sand 

levels. All of the reservoir level data have been linked to the sand, pool, play, chronozone, and series level to support 

the Offshore Atlas Project (OAP). 

The MMS OCS Report MMS 2001-086, Atlas of Gulf of Mexico Gas and Oil Sands as of January 1, 1999, 

provides a detailed geologic reporting of oil and gas proved and unproved reserves. Reserves data on more than

10,000 sands have been placed into 65 established geological plays in Federal waters. This is the second MMS 

release of a comprehensive framework of geologic and reserve data and the associated attributes for each specific 

sand and field. Play, chronozone, series, system, province, and region levels can also be evaluated with the data 

provided. 

The MMS OCS Report MMS 2001-087, 2000 Assessment of Conventionally Recoverable Hydrocarbon 

Resources of the Gulf of Mexico and Atlantic Outer Continental Shelf as of January 1, 1999, also known as the 

National Assessment, and it’s update, Assessment of Undiscovered Technically Recoverable Oil and Gas 

Resources of the Nation’s Outer Continental Shelf, 2006, address proved and unproved reserves, reserves 

appreciation, and undiscovered resources. To maintain credibility, an estimate of undiscovered resources must be 

based on discovered resources. The OAP supported this report by providing a framework of hydrocarbon plays that 

allowed for the logical extension of existing production rather than just a conceptual estimate. This report contains 

reserves and resource estimates by play, planning area, water depth, and region. 

For information on these reports, contact the Gulf of Mexico Region’s Public Information Office at 1-800-200-GULF or 

504-736-2519, or visit MMS’s Gulf of Mexico Region Internet Web site at http://www.gomr.mms.gov. 

Methods Used for Estimating Reserves

Reserve estimates from geological and engineering analyses have been completed for the 1,196 proved fields. 

Reserves accountability is dependent on the drilling and development phases of fields. When a field is in the 

unproved category, geophysical mapping and limited well data are the basis for defining reservoir limits. Once a field 

is moved into the proved category and more data become available, the reserve estimate is re-evaluated. Well logs, 

well file data, seismic data, and production data are continually analyzed to improve the accuracy of the reserve 

estimate. As a field is depleted and/or abandoned, the proved reserves of productive reservoirs are assigned a value 

equal to the amount produced and the reserve estimate of non-producing reservoirs is converted to known resources. 

Currently, there are 245 proved expired, depleted fields. 

Estimation of reserves is done under conditions of uncertainty. The method of estimation is called deterministic if the 

estimate is a single “best estimate” based on known geological, engineering, and economic data. The method of 

estimation is called probabilistic when the known geoscience, engineering, and economic data are used to generate a 

continuous range of estimates and their associated probabilities (SPE/AAPG/WPC/SPEE, 2007). Reserve estimates 

in this report are deterministic. 

Methods used for estimating reserves can be categorized into three groups: analog, volumetric, and performance. 

The accuracy of the proved reserve estimate improves as more reservoir data become available to geoscientists and 

engineers. Resources are based on analogy with similar fields, reservoirs, or wells in the same area. Reserve 

estimates in this report are based primarily on volumetric and performance methods. 

Analog

In the estimation of resources by analogy, geoscientists use seismic data to generate maps of the extent of 

subsurface formations. Estimates of undiscovered resources are based on analogy with similar fields, reservoirs, or 

wells in the same area before any wells have been drilled on a prospect. The seismic data help geoscientists identify 

prospects and resources, but do not provide enough direct data alone to estimate reserves. 

The effective pore space, water saturation, net hydrocarbon thickness, pressure, volume, and temperature data, all 

necessary to complete resource estimates for prospects, come from nearby field and reservoir well data. After one or 

more wells are drilled and found producible, a volumetric estimate is done. These estimates, while incorporating 

existing data, still rely on some information obtained from analogs. 
6

Volumetric

In a volumetric reserve estimate, data from drilled wells and seismic surveys are used to develop geologic 

interpretations. The effective pore space (porosity), water saturation, and net hydrocarbon thickness of the 

subsurface formations are calculated through evaluation of well logs, core analysis, and formation test data. 

Subsurface formations are mapped to determine area and net hydrocarbon thickness for each reservoir. Reservoir 

pressure, fluid volume, and temperature data from formation fluid samples are used to determine the change in 

volume of oil and gas that flow from higher pressure conditions deep underground to lower pressure conditions at the 

surface. All of these data are compiled, analyzed and applied to standard equations for the calculation of 

hydrocarbons in place within the reservoirs. Standard recovery factor equations are then applied to the in-place 

estimates to calculate proved and unproved reserves. 

Performance Methods

In performance-technique methods, reserves are estimated by using mathematical or graphical techniques of 

production decline curve analysis and material balance. These techniques are used throughout the oil industry in 

assessing individual well, reservoir, or field performance and in forecasting future reserves. In decline analysis, a plot 

of daily production rate against time is most frequently used. Once a well or reservoir can no longer produce at its 

maximum capacity, the production rate declines. This production rate plotted against time can be extrapolated into 

the future to predict the remaining reserves. Another type of decline analysis is daily production rate plotted against 

cumulative production, which can also be used to predict remaining reserves. The declining daily rate is extrapolated 

to predict remaining reserves. 

Another performance method, material balance, is used to estimate the amount of hydrocarbons in place. Given the 

premise that the pressure-volume relationship of a reservoir remains constant as hydrocarbons are produced, it is 

possible to equate expansion of reservoir fluids with reservoir voidage caused by fluid withdrawal minus any water 

influx. For depletion-drive gas reservoirs, a plot of the pressure/gas compressibility factor (P/Z) versus cumulative 

gas production provides an estimate of gas-in-place. Recoverable gas reserves are extrapolated to an abandonment 

reservoir pressure. 

Reserves and Related Data Reported by Area

The Gulf of Mexico has been divided into three planning areas for administrative purposes; these planning areas as of 

December 31, 2005 (Western, Central, and Eastern) are shown in Figures 4, 5, and 6, respectively. Each planning 

area is subdivided into protractions, which in turn are divided into numbered blocks. Fields in the Gulf of Mexico are 

identified by the protraction area name and block number of discovery – for example, East Cameron Block 271 Field. 

TEXAS

LOUISIANA

Sabine

Pass

High 

Island Galveston

Brazos

Matagorda

Island

Mustang

Island

North

Padre

Island

South

Padre

Island

Corpus

Christi Port

Isabel

East

Breaks

Alaminos

Canyon

Garden

Banks

Keathley

Canyon

Sigsbee

Escarpment

N

TEXAS

LOUISIANA

Sabine

Pass

High 

Island Galveston

Brazos

Matagorda

Island

Mustang

Island

North

Padre

Island

South

Padre

Island

Corpus

Christi Port

Isabel

East

Breaks

Alaminos

Canyon

Garden

Banks

Keathley

Canyon

Sigsbee

Escarpment

N

Figure 4. Western Planning Area, Gulf of Mexico, Outer Continental Shelf.
7

LOUISIANA

MISSISSIPPI

West

Cameron

East

Cameron

Vermilion

South

Marsh Island

Eugene

Island

Ship

Shoal

South

Timbalier

South

Pelto Grand 

Isle

West 

Delta

Main

Pass

Green

Canyon

Mississippi

Canyon

Atwater

Valley

Walker

Ridge Lund

Amery Terrace Lund South

Viosca

Knoll

(Shelf)

Viosca

Knoll (Slope)

Ewing

Bank

South Pass

Chandeleur

Breton

Bay Sound

Marchand

Mobile

N

Figure 5. Central Planning Area, Gulf of Mexico, Outer Continental Shelf. 

Destin

Dome

DeSoto

Canyon

Florida Middle 

Ground

Apalachicola

Lloyd

Ridge

The

Elbow

Tarpon

Springs

Saint 

Petersburg

Henderson

Vernon

Basin

Charlotte

Harbor

Florida

Plain Howell

Hook

Pulley

Ridge

Rankin Dry

Tortugas

Miami

Tortugas

Valley

Pensacola

Gainesville

Key

West

FLORIDA

N

Figure 6. Eastern Planning Area, Gulf of Mexico, Outer Continental Shelf. 

As the field is developed, the limits may expand into adjacent blocks and areas. These adjacent blocks are then 

identified as part of the original field and are given that field name. Statistics in this report are presented as area 

totals compiled under each field name. All of the data associated with East Cameron Block 271 Field are therefore 

included in the East Cameron totals, although part of the field extends into the adjacent area of Vermilion. There are 

four exceptions to the above field-naming techniques: Tiger Shoal and Lighthouse Point, included in South Marsh 

Island; Coon Point, included in Ship Shoal; and Bay Marchand, included in South Timbalier. 
8

Through December 31, 2005, there were 1,007 proved and unproved active fields in the federally regulated part of the 

Gulf of Mexico. An updated list of the active and expired fields can be found in the OCS Operations Field Directory

(updated monthly) available from MMS’s Gulf of Mexico Region Internet Web site. There were 951 proved, active 

(producing and non-producing) fields and 56 unproved active fields studied. Included are the 245 proved expired, 

depleted fields, abandoned after producing 2.5 percent barrel oil equivalent of the total cumulative oil and gas 

production. Not studied were 96 fields expired, relinquished, or terminated without production. These fields may also 

be included in the Indicated Hydrocarbon List that can be found by visiting the MMS’s Gulf of Mexico Region 

Internet Web site. In 2005, 39 proved fields expired including 14 proved fields that were depleted. 

Reserves data and various classifications of fields, leases, boreholes, and completions are presented as area totals in 

Tables 1 and 2, and the Table 3 series. (The Table 3 series will be discussed in the section “Reserves Reported by 

Geologic Age,” beginning on page 12.) 

Table 1. Estimated oil and gas reserves for 1,196 proved fields and 56 unproved fields by area, 

Gulf of Mexico, Outer Continental Shelf, December 31, 2005. 

Proved Proved Proved

active active expired

prod nonprod depleted active studied Oil Gas Oil Gas Oil Gas Oil Gas

Western Planning Area

Western Shelf

Brazos 23 3 12 0 0 2 11 3,655 10 3,366 1 289 0 63

Galveston 20 4 22 0 0 3 68 2,174 53 1,924 15 250 0 48

High Island and Sabine Pass 73 10 43 1 1 8 393 15,289 373 14,671 20 618 9 287

Matagorda Island 23 0 5 0 0 3 24 5,175 23 4,941 1 234 1 377

Mustang Island 13 0 15 0 0 6 12 1,784 5 1,668 7 116 13 138

N.& S.Padre Island 7 1 6 0 0 0 0 590 0 515 0 75 0 8

Western Slope

Alaminos Canyon 3 0 0 4 4 1 72 123 56 87 16 36 373 554

East Breaks 18 1 0 2 2 4 231 2,338 156 1,429 75 909 16 101

Garden Banks 27 3 3 4 4 4 654 3,840 453 2,922 201 918 173 629

Western Slope (Other)* 0 0 0 1 1 1 0 0 0 0 0 0 8 4

Western Planning Area Subtotal 207 22 106 12 12 32 1,465 34,968 1,129 31,523 336 3,445 593 2,209

Central Planning Area

Central Shelf

Chandeleur 6 3 3 0 0 0 0 367 0 347 0 20 0 4

East Cameron 44 10 12 0 0 0 356 10,883 321 10,338 35 545 4 127

Eugene Island 71 5 10 0 0 6 1,631 19,223 1,571 18,608 60 615 36 249

Grand Isle 13 3 5 0 0 1 975 4,807 947 4,613 28 194 19 111

Main Pass and Breton Sound 59 7 17 0 0 6 1,109 6,589 1,012 6,065 97 524 6 34

Mobile 19 3 5 0 0 4 0 2,157 0 1,778 0 379 0 127

Ship Shoal 50 3 10 1 0 4 1,382 12,095 1,325 11,566 57 529 21 178

South Marsh Island 38 7 6 0 0 0 939 14,368 856 13,612 83 756 14 277

South Pass 8 3 2 0 0 1 1,075 4,334 1,048 4,198 27 136 2 71

South Pelto 9 0 0 0 0 0 157 1,151 146 1,036 11 115 4 14

South Timbalier 47 3 8 2 2 2 1,611 10,487 1,468 9,218 143 1,269 33 367

Vermilion 62 6 17 0 0 1 572 16,573 521 15,717 51 856 18 318

Viosca Knoll (Shelf) 14 1 13 4 4 1 12 461 11 399 1 62 0 18

West Cameron and Sabine Pass 80 9 24 1 1 1 220 20,712 199 19,130 21 1,582 10 379

West Delta 20 1 3 0 0 3 1,372 5,503 1,338 5,265 34 238 11 76

Central Slope

Ewing Bank 14 1 0 1 1 2 331 532 229 359 102 173 53 104

Green Canyon 28 6 2 9 9 16 2,478 3,635 766 2,063 1,712 1,572 740 587

Mississippi Canyon 30 9 1 10 10 8 3,528 8,956 1,325 5,555 2,203 3,401 651 1,935

Viosca Knoll (Slope) 18 1 1 2 2 3 510 2,864 373 2,214 137 650 86 194

Atwater Valley 0 4 0 4 4 3 48 404 0 0 48 404 76 152

Central Slope (Other)** 1 0 0 6 6 0 29 173 26 154 3 19 850 163

Central Planning Area Subtotal 631 85 139 40 39 62 18,335 146,274 13,482 132,235 4,853 14,039 2,634 5,485

Eastern Planning Area Subtotal*** 2 4 0 4 4 2 1 542 0 88 1 454 0 703

840 111 245

1,196

 ***Eastern Planning Area includes DeSoto Canyon, Destin Dome, Lloyd Ridge, and others.

96 19,801 181,784 14,611 163,846 5,190 17,938 3,227

 **Central Slope (Other) includes Lund and Walker Ridge.

 *Western Slope (Other) includes Corpus Christi, Keathley Canyon, and Port Isabel.

GOM Total: 56 55 8,397

(Figs. 4, 5, and 6) reserves through 2005 reserves Expired 

nonprod

 Proved production proved

 (Reserves: oil expressed in millions of barrels at 60 °F and 1 atmosphere; gas in billions of cubic feet at 60 °F and 15.025 psia.)

Number of fields Cumulative Remaining

Unproved 

reserves

Area(s) Unproved
9

Figure 7 provides a geographical representation of locations for the 1,196 proved fields in the Gulf of Mexico. The 

bar heights in the figure are proportional to total proved reserves (barrel of oil equivalent) for each proved field by 

decade. 

Figure 8 provides a geographical representation of the 56 unproved active fields in the Gulf of Mexico. Estimates of 

unproved reserves are presented as planning area subtotals. The bar heights in the figure are proportional to total 

unproved reserves (barrel of oil equivalent) for each unproved field by decade. 

Figure 7. Gulf of Mexico, 1,196 proved fields (951 active and 245 depleted.) 

Figure 8. Gulf of Mexico, 56 unproved active fields. 
10

Table 2. Status of oil and gas leases, boreholes, and completions by area, Gulf of Mexico, 

Outer Continental Shelf, December 31, 2005. 

(All statistics associated with fields are presented within area totals compiled under each field name.)

Area(s)

(Figs. 4, 5, and 6) Proved Proved Unproved Unqualified

active depleted qualified active Drilled Abandoned

Western Planning Area

Western Shelf

Brazos 36 57 0 62 339 581 434 173

Galveston 38 72 0 129 572 693 610 129

High Island and Sabine Pass 179 194 0 212 973 3,471 2,503 1,181

Matagorda Island 46 45 0 36 145 633 417 275

Mustang Island 26 36 0 64 395 447 338 139

N.& S.Padre Island 18 14 0 56 321 168 133 48

Western Slope

Alaminos Canyon 4 1 7 541 150 48 27 8

East Breaks 37 8 0 258 449 363 235 132

Garden Banks 55 31 1 512 815 584 411 166

Western Slope (Other)* 9 1 0 609 311 20 18 0

Western Planning Area Subtotal 448 459 8 2,479 4,470 7,008 5,126 2,251

Central Planning Area

Central Shelf

Chandeleur 9 14 0 19 33 82 58 29

East Cameron 125 145 0 116 605 2,277 1,638 905

Eugene Island 218 137 2 120 472 5,396 3,698 2,025

Grand Isle 50 36 0 43 145 1,904 1,507 571

Main Pass and Breton Sound 150 115 5 103 391 3,130 1,929 1,526

Mobile 37 18 0 26 88 171 105 63

Ship Shoal 175 102 2 136 472 3,627 2,284 1,582

South Marsh Island 132 81 2 80 327 2,900 1,823 1,219

South Pass 40 24 1 24 92 2,326 1,442 1,053

South Pelto 19 7 0 5 30 416 291 195

South Timbalier 140 81 2 135 451 3,252 2,073 1,469

Vermilion 144 172 3 147 574 3,091 2,164 1,200

Viosca Knoll (Shelf) 22 24 0 80 213 252 173 44

West Cameron and Sabine Pass 224 262 3 281 924 3,684 2,677 1,370

West Delta 89 53 0 36 184 2,943 1,975 1,044

Central Slope

Atwater Valley 6 5 3 373 327 80 68 6

Ewing Bank 32 14 0 64 235 341 235 123

Green Canyon 99 36 9 681 652 954 681 292

Mississippi Canyon 132 33 1 539 677 1,410 925 473

Viosca Knoll (Slope) 40 14 0 42 125 340 193 164

Central Slope (Other)** 35 0 7 516 133 31 23 1

Central Planning Area Subtotal 1,918 1,373 40 3,566 7,150 38,607 25,962 15,354

Eastern Planning Area Subtotal*** 5 8 86 155 349 83 67 11

GOM Total: 2,371 1,840 134 6,200 11,969 45,698 31,155 17,616

 *Western Slope (Other) includes Corpus Christi, Keathley Canyon, and Port Isabel.

 **Central Slope (Other) includes Lund and Walker Ridge.

 ***Eastern Planning Area includes DeSoto Canyon, Destin Dome, Lloyd Ridge, and others.

Number of leases Number 

of 

boreholes

Number 

of active 

Expired completions

The status of Gulf of Mexico OCS Federal oil and gas leases as of December 31, 2005, is presented in Table 2. 

There are 8,705 active leases (2,371 proved active, 134 unproved qualified, and 6,200 unqualified active) and 13,809 

relinquished leases (1,840 proved depleted and 11,969 expired). 

Definitions for the lease subgroups of Table 2 are: 

Proved Active — Leases within the designated 951 proved active fields presented in Table 1. 

Proved Depleted — Leases relinquished after oil and gas production. The leases associated with the 245 depleted 

fields are represented here along with other produced, relinquished leases that are part of currently active fields. 

Unproved Qualified — Leases associated with the 56 unproved active fields. The leases have qualified as 

producible under 30 CFR 250.115/116, but the operators have not established a commitment to produce. These 

fields may be classified as unproved possible or unproved probable. 
11

Foraminifer & Ostracod (O) Nannoplanktin

Globorotalia inflata

Globorotalia flexuosa Emiliania huxleyi (base of acme)

Sangamon fauna Gephyrocapsa oceanica (flood)

Gephyrocapsa caribbeanica (flood)

Helicosphaera inversa

Trimosina "A" Gephyrocapsa parallela

Pseudoemiliania ovata

Stilostomella antillea Pseudoemiliania lacunosa "C" (acme)

Trimosina "A" (acme)

Hyalinea "B" / Trimosina "B"

Angulogerina "B" Calcidiscus macintyrei

Uvigerina hispida

Globorotalia crassula (acme) Discoaster brouweri

Lenticulina 1

Globoquadrina altispira

Textularia 1

Buccella hannai (acme) Sphenolithus abies

Buliminella 1 Sphenolithus abies "B"

Globorotalia plesiotumida (acme) Discoaster quintatus

Globorotalia menardii (coiling change right-to-left) Discoaster quinqueramus

Textularia "X" Discoaster berggrenii "A"

Robulus "E"

Bigenerina "A" Minylithus convallis

Cristellaria "K" Catinaster mexicanus

Bolivina thalmanni Discoaster prepentaradiatus (increase)

Discorbis 12

Bigenerina 2 Helicosphaera walbersdorfensis

Uvigerina 3 Coccolithus miopelagicus

Globorotalia fohsi robusta Discoaster kugleri

Textularia "W" Discoaster kugleri (acme)

Globorotalia peripheroacuta Discoaster sanmiguelensis (increase)

Bigenerina humblei

Cristellaria "I" Sphenolithus heteromorphus

Cibicides opima Sphenolithus heteromorphus (acme)

Cristellaria / Robulus / Lenticulina 53 Helicosphaera ampliaperta

Amphistegina "B" Discoaster deflandrei (acme)

Robulus 43 Discoaster calculosus

Cibicides 38

Cristellaria 54 / Eponides 14

Gyroidina "K" Reticulofenestra gartneri

Catapsydrax stainforthi Sphenolithus disbelemnos

Discorbis "B" Orthorhabdus serratus

Marginulina "A" Triquetrorhabdulus carinatus

Siphonina davisi Discoaster saundersi

Lenticulina hanseni

Helicosphaera recta

Robulus "A" Dictyococcites bisectus

Heterostegina texana Sphenolithus delphix

Camerina "A"

Bolivina mexicana

Nonion struma

Textularia warreni Sphenolithus pseudoradians

Ismolithus recurvus

Hantkenina alabamensis Discoaster saipanensis

Camerina moodybranchensis Cribrocentrum reticulatum

Sphenolithus obtusus

Nonionella cockfieldensis Micrantholithus procerus

Discorbis yeguaensis Pemma basquensis

Discoaster lodoensis

Chiasmolithus californicus

Globorotalia wilcoxensis Toweius crassus

Discoaster multiradiatus

Morozovella velascoensis Fasciculithus tympaniformis

Vaginulina longiforma

Vaginulina midwayana

Globorotalia trinidadensis Chiasmolithus danicus

Globigerina eugubina

Micula decussata

Abathomphalus mayaroensis Micula prinsii FAD

Rosita fornicata

Dicarinella concavata Lithastrinus moratus

Hedbergella amabilis Stoverius achylosus

Dicarinella hagni

Planulina eaglefordensis

Rotalipora cushmani Lithraphidites acutus

Favusella washitaensis

Rotalipora gandolfii

Hayesites albiensis

Cythereis fredericksburgensis (O) Braarudosphaera hockwoldensis

Ammobaculites goodlandensis

Dictyoconus walnutensis

Eocytheropteron trinitiensis (O) Rucinolithus irregularis

Orbitolina texana

Rehacythereis? aff. R. glabrella (O)

Ticinella bejaouaensis

Choffatella decipiens

Schuleridea acuminata (O) Diadorhombus rectus

Polycostella beckmanni

Gallaecytheridea postrotunda (O)

Epistomina uhligi

Epistomina mosquensis Stephanolithion bigotii bigotii

Alveosepta jaccardi Stephanolithion bigotii maximum

Paalzowella feifeli Stephanolithion speciosum

Reinholdella crebra

Watznaueria crucicentralis

Chronostratigraphy Biostratigraphy MMS 

Chronozone

Province System Subsystem Series

Holocene

C

e

n

o

z

o

i

c

Quaternary Pleistocene

Upper

T

e

r

t

i

a

r

y

N

e

o

c

e

n

e

Pliocene

Upper

P

a

l

e

o

g

e

n

e

Oligocene

PLU

Middle PLM

Lower PLL

PU

Lower PL

Miocene

Upper

MUU

MLU

Middle

MUM

MMM

MLM

Lower

MUL

MML

MLL

Upper OU

Lower OL

Eocene

Upper EU

Middle EM

Lower EL

Paleocene Upper LU

Lower LL

Comanchean

Lower

KUL

KML

KLL Coahuilan

Upper Gulfian

JU

Middle JM

Abbreviated MMS Gulf of Mexico biostratigraphic chart illustrating chronostratigraphy, biostratigraphy, and MMS chronozones codes. For the complete chart visit : 

http:/www.gomr.mms.gov/homepg/whatsnew/papers/biochart.pdf. 

M

e

s

o

z

o

i

c

C

r

e

t

a

c

e

o

u

s

Jurassic

Upper

KUU

KLU

Figure 9. Gulf of Mexico geologic time scale. 
12

Unqualified Active — Active exploratory leases not yet qualified as producible or associated with any field. 

Expired — Leases expired, terminated, or relinquished by the operator without having produced any oil or gas, 

although some were once qualified as producible under 30 CFR 250.115/116. There are 96 expired fields with no 

production. 

The total number of boreholes drilled and the number of boreholes plugged and abandoned are also shown in Table 

2. There were 816 boreholes spudded during 2005, compared with 897 during 2004, and 893 during 2003. The last 

column of Table 2 presents the total number of active completions per area. Active completions are defined as those 

with perforations open to the formation and not isolated by permanent plugs; service wells (injection, disposal, or 

water source) are included. The presence or absence of production or injection is not considered. The number of 

boreholes and the number of active completions listed in this report are based on reports received by the MMS at the 

time the count was made in 2008. These numbers may change as data are received, processed, and edited. 

Reserves Reported by Geologic Age

In this report, the 1,196 proved and 56 unproved fields have been classified at the geologic series level. The different 

geologic age classifications currently in use by MMS are shown in Figure 9. Paleontological examinations of borehole 

cuttings, along with regional analysis of geological and geophysical data, were used in determining the age 

classifications. Hundreds of additional foraminiferal and nannofossil bioevents were incorporated into an update of 

the MMS Biostratigraphic Chart (www.gomr.mms.gov/homepg/whatsnew/papers/biochart.pdf) to aid in geologic 

mapping, stratigraphic correlation, and paleobathymetric zonation. Using standardized global stratigraphic concepts, 

this new version of the chart incorporates the latest information currently used as biostratigraphic datum markers by 

industry paleontologists for the Mesozoic and Cenozoic geologic provinces. This biostratigraphic chart update 

reduces the disjoint between the industry/academia biostratigraphic naming convention and the MMS-standard 

chronozone naming convention, hence MMS reserves allocations. 

Table 3 shows the distribution of reserves and production data by geologic age and planning area. Tables 3a 

through 3e also show the distribution of reserves and production data by geologic age, but further subdivide the 

planning areas as area totals. Please note that this report contains the term “Span Ages,” which is used to denote a 

geologic age classification that spans more than one series (see Tables 3 and 3e). 

Table 3. Estimated oil and gas reserves for 1,196 proved and 56 unproved fields by geologic age, 

Gulf of Mexico, Outer Continental Shelf, December 31, 2005. 

 Oil Gas Oil Gas Oil Gas Oil Gas

Western Planning Area

Pleistocene 1,109 285 7,775 198 7,254 87 521 148 49 267

Pliocene 860 947 8,189 745 6,698 202 1,491 128 122 507

Miocene 2,445 232 18,971 185 17,550 47 1,421 238 41 882

Pre-Miocene 8 0 33 0 20 0 13 0 0 0

Span Ages 0 0 0 0 0 0 0 18 381 553

Western Planning Area Subtotal 4,422 1,464 34,968 1,128 31,522 336 3,446 532 593 2,209

Central Planning Area

Pleistocene 3,448 1,118 20,418 1,015 19,277 103 1,141 310 71 432

Pliocene 9,493 6,052 48,343 5,203 45,212 849 3,131 748 213 1,245

Miocene 11,234 9,848 74,646 7,253 66,056 2,595 8,590 904 786 3,080

Pre-Miocene 36 0 2,069 0 1,688 0 381 9 0 143

Span Ages 43 1,318 798 12 3 1,306 795 35 1,564 585

Central Planning Area Subtotal 24,254 18,336 146,274 13,483 132,236 4,853 14,038 2,006 2,634 5,485

Eastern Planning Area

Miocene 12 1 542 0 88 1 454 12 0 212

Pre-Miocene 0 0 0 0 0 0 0 1 0 491

Eastern Planning Area Subtotal 12 1 542 0 88 1 454 13 0 703

GOM Total 28,688 19,801 181,784 14,611 163,846 5,190 17,938 2,551 3,227 8,397

 reserves through 2005 reserves reserves

 Proved production proved Unproved Area

Number of 

proved 

reservoirs

Number of 

unproved 

reservoirs

(Reserves: oil expressed in millions of barrels at 60 oF and 1 atmosphere, gas in billions of cubic feet at 60 oF and 15.025 psia.)

 Cumulative Remaining
13

Data from Table 3a were used to generate the Pleistocene reserves trend presented in Figure 10 and correspond to 

the Globorotalia flexuosa through Uvigerina hispida biozones. Production within the Pleistocene extends from the 

Galveston area to east of the modern-day mouth of the Mississippi River. Pleistocene productive sands are limited in 

the east and west because of a lack of sediment influx at the edge of the depocenter. Deepwater Pleistocene 

production occurs in the East Breaks through Mississippi Canyon areas, and well control suggests sands continue 

beyond the Sigsbee Escarpment. Through December 31, 2005, the Pleistocene produced from 397 fields. Proved 

reserves were 1.40 billion barrels (Bbbl) and 28.2 trillion cubic feet (Tcf). Remaining proved reserves were 0.19 Bbbl 

and 1.7 Tcf. 

Table 3a. Estimated oil and gas reserves for Pleistocene reservoirs in 397 proved and 10 unproved fields 

by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005. 

 Oil Gas Oil Gas Oil Gas Oil Gas

Western Planning Area

Alaminos Canyon 0000000 105

East Breaks 32 9 200 6 139 3 61 3 0 7

Galveston 2 0 15 0 15 0 0 0 0 0

Garden Banks 110 136 1,366 57 1,119 79 247 61 46 169

High Island and Sabine Pass 959 140 6,169 135 5,981 5 188 82 3 82

N & S Padre Island 6 0 25 0 0 0 25 1 0 4

Western Slope (Other)* 0 000000 000

Western Planning Area Subtotal 1,109 285 7,775 198 7,254 87 521 148 49 267

Central Planning Area

Atwater Valley 0 0 0 0 0 0 0 1 0 22

East Cameron 341 201 1,488 184 1,333 17 155 44 2 34

Eugene Island 822 323 5,544 305 5,436 18 108 24 2 19

Ewing Bank 62 38 233 28 173 10 60 18 23 50

Grand Isle 34 0 89 0 80 0 9 4 0 2

Green Canyon 146 85 562 72 461 13 101 50 12 54

Main Pass and Breton Sound 4 0 16 0 16 0 0 0 0 0

Mississippi Canyon 27 7 690 5 578 2 112 10 8 19

Ship Shoal 275 67 1,784 64 1,747 3 37 12 1 9

South Marsh Island 429 246 1,887 226 1,787 20 100 32 3 50

South Pass 26 1 240 1 240 0 0 1 0 0

South Pelto 9 0 10 0 6 0 4 0 0 0

South Timbalier 203 46 1,011 42 909 4 102 13 2 15

Vermilion 520 81 1,726 70 1,621 11 105 45 12 93

Viosca Knoll (Slope) 2 0 28 0 0 0 28 0 0 0

West Cameron and Sabine Pass 521 23 4,965 18 4,761 5 204 56 6 65

West Delta 27 0 145 0 129 0 16 0 0 0

Central Slope (Other)** 0 000000 000

Central Planning Area Subtotal 3,448 1,118 20,418 1,015 19,277 103 1,141 310 71 432

Eastern Planning Area Subtotal*** 0 0 0 0 0 0 0 0 0 0

GOM Total 4,557 1,403 28,193 1,213 26,531 190 1,662 458 120 699

 *Western Slope (Other) includes Corpus Christi, Keathley Canyon, and Port Isabel.

 **Central Slope (Other) includes Lund and Walker Ridge.

 ***Eastern Planning Area includes DeSoto Canyon, Destin Dome, Lloyd Ridge, and others.

 Unproved

 reserves reserves

 production 

 through 2005

 proved

 reserves Area

Number of 

proved 

reservoirs

Number of 

unproved 

reservoirs

(Reserves: oil expressed in millions of barrels at 60 oF and 1 atmosphere, gas in billions of cubic feet at 60 oF and 15.025 psia.)

 Cumulative Remaining

 Proved

Data from Table 3b were used to generate the Pliocene reserves trend presented in Figure 11 and correspond to the 

Globorotalia crassula (acme) through Globorotalia plesiotumida (acme) biozones. Production within the Pliocene 

extends from south of Galveston in the west to south of Mobile Bay in the east. Pliocene deepwater production 

extends extend into the areas of East Breaks, Garden Banks, Green Canyon, Ewing Bank, and Mississippi Canyon. 

Well control suggests Pliocene sands extend at least as far as the Sigsbee Escarpment. Through December 31, 

2005, the Pliocene produced from 533 fields. Proved reserves were 7.00 Bbbl and 56.5 Tcf. Remaining proved 

reserves were 1.05 Bbbl and 4.6 Tcf. 
14

Figure 10. Pleistocene reserves trend. 

Figure 11. Pliocene reserves trend. 
15

Table 3b. Estimated oil and gas reserves for Pliocene reservoirs in 533 proved and 21 unproved fields 

by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005. 

 Oil Gas Oil Gas Oil Gas Oil Gas

Western Planning Area

Alaminos Canyon 2 63 116 48 81 15 35 0 0 0

East Breaks 141 221 1,810 149 1,077 72 733 29 16 94

Galveston 20 1 70 1 69 0 1 0 0 0

Garden Banks 87 459 2,233 355 1,631 104 602 51 103 366

High Island and Sabine Pass 610 203 3,960 192 3,840 11 120 48 3 47

Western Slope (Other)* 0 000000 000

Western Planning Area Subtotal 860 947 8,189 745 6,698 202 1,491 128 122 507

Central Planning Area

Atwater Valley 0000000 244

East Cameron 547 74 4,845 62 4,627 12 218 60 2 58

Eugene Island 1,536 881 7,845 855 7,613 26 232 129 15 62

Ewing Bank 50 252 248 182 165 70 83 14 15 37

Grand Isle 194 43 1,810 41 1,771 2 39 13 1 5

Green Canyon 193 1,045 2,202 652 1,559 393 643 73 64 165

Main Pass and Breton Sound 119 65 723 58 696 7 27 1 0 1

Mississippi Canyon 265 538 2,685 394 2,457 144 228 65 61 376

Ship Shoal 1,800 1,032 7,324 994 6,981 38 343 101 8 84

South Marsh Island 688 366 3,544 330 3,311 36 233 50 7 55

South Pass 797 538 2,329 525 2,244 13 85 23 1 47

South Pelto 145 49 57 48 55 1 2 2 2 7

South Timbalier 1,061 404 4,967 359 4,579 45 388 115 12 205

Vermilion 845 264 4,241 238 4,038 26 203 47 3 66

Viosca Knoll (Slope) 22 53 109 34 85 19 24 4 9 8

West Cameron and Sabine Pass 646 30 4,084 28 3,787 2 297 35 2 47

West Delta 533 389 1,157 377 1,090 12 67 11 7 14

Central Slope (Other)** 52 29 173 26 154 3 19 3 0 4

Central Planning Area Subtotal 9,493 6,052 48,343 5,203 45,212 849 3,131 748 213 1,245

Eastern Planning Area Subtotal*** 0 0 0 0 0 0 0 0 0 0

GOM Total 10,353 6,999 56,532 5,948 51,910 1,051 4,622 876 335 1,752

 *Western Slope (Other) includes Corpus Christi, Keathley Canyon, and Port Isabel.

 **Central Slope (Other) includes Lund and Walker Ridge.

 ***Eastern Planning Area includes DeSoto Canyon, Destin Dome, Lloyd Ridge, and others.

 production proved Unproved

 reserves through 2005 reserves reserves Area

Number of 

proved 

reservoirs

Number of 

unproved 

reservoirs

(Reserves: oil expressed in millions of barrels at 60 oF and 1 atmosphere, gas in billions of cubic feet at 60 oF and 15.025 psia.)

 Cumulative Remaining

 Proved

Data from Table 3c were used to generate the Miocene reserves trend presented in Figure 12 and correspond to the 

Globorotalia menardii (coiling change right-to-left) through Lenticulina hanseni biozones. Production within the 

Miocene extends from North Padre Island in the west to east of the Mississippi River. Miocene productive sands also 

extend into deepwater from East Breaks and Garden Banks in the west to Ewing Bank, Green Canyon, Viosca Knoll, 

Mississippi Canyon, Atwater Valley, Destin Dome, Desoto Canyon, and Lloyd Ridge in the east. Wells indicate sands 

continue beyond the Sigsbee Escarpment. Through December 31, 2005 the Miocene produced from 709 fields. 

Proved reserves were 10.08 Bbbl and 94.2 Tcf. Remaining proved reserves were 2.64 Bbbl and 10.5 Tcf. 

Data from Table 3d were used to generate the Pre-Miocene reserves trend presented in Figure 13 and include the 

Oligocene, Eocene, and Paleocene in the Tertiary series, and the Cretaceous and Jurassic series. These reservoirs 

include Jurassic Norphlet sands and Lower Cretaceous Carbonates. Production within the Jurassic is limited to east 

of the Mississippi River in the Mobile area. Well control suggests reservoir sands continuing eastward into Destin 

Dome. Through December 31, 2005, these trends produced from 23 fields. Proved reserves were less than 0.01 Bbbl 

and 2.1 Tcf. Remaining proved reserves were less than 0.01 Bbbl and 0.4 Tcf. 

Data from Table 3e were used to generate reserves for the reservoirs in fields that span ages from Upper Pleistocene 

to the Lower Paleogene. Proved reserves were 1.3 Bbbl and 0.8 Tcf. 
16

Table 3c. Estimated oil and gas reserves for Miocene reservoirs in 709 proved and 18 unproved fields 

by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005. 

 Oil Gas Oil Gas Oil Gas Oil Gas

Western Planning Area

Alaminos Canyon 1 10 7 8 6 2 1 0 0 0

Brazos 432 11 3,655 10 3,366 1 289 43 0 63

East Breaks 5 1 329 1 214 0 115 0 0 0

Galveston 402 66 2,089 51 1,840 15 249 31 0 48

Garden Banks 7 59 242 41 173 18 69 9 23 93

High Island and Sabine Pass 688 50 5,159 47 4,849 3 310 56 4 159

Matagorda Island 464 24 5,175 23 4,941 1 234 67 1 377

Mustang Island 333 11 1,751 4 1,647 7 104 28 13 138

N.& S.Padre Island 113 0 564 0 514 0 50 4 0 4

Western Slope (Other)* 0000000 000

Western Planning Area Subtotal 2,445 232 18,971 185 17,550 47 1,421 238 41 882

Central Planning Area

Atwater Valley 11 1 361 0 0 1 361 6 18 46

Chandeleur 28 0 367 0 347 0 20 5 0 4

East Cameron 409 80 4,552 74 4,379 6 173 21 0 35

Eugene Island 1,292 428 5,833 411 5,560 17 273 153 19 167

Ewing Bank 10 41 51 20 21 21 30 6 15 17

Grand Isle 726 932 2,908 906 2,761 26 147 102 18 104

Green Canyon 14 78 116 32 39 46 77 15 6 23

Main Pass and Breton Sound 1,446 1,044 5,850 954 5,353 90 497 10 6 32

Mississippi Canyon 162 2,983 5,581 924 2,520 2,059 3,061 90 583 1,542

Mobile 33 0 383 0 333 0 50 1 0 1

Ship Shoal 821 282 2,989 267 2,838 15 151 49 11 85

South Marsh Island 902 328 8,935 301 8,513 27 422 79 3 172

South Pass 569 536 1,766 521 1,715 15 51 7 1 23

South Pelto 412 108 1,083 98 974 10 109 8 2 7

South Timbalier 1,177 1,162 4,509 1,067 3,730 95 779 91 19 146

Vermilion 984 228 10,606 213 10,057 15 549 90 3 158

Viosca Knoll (Shelf) 31 12 165 11 156 1 9 4 0 1

Viosca Knoll (Slope) 101 456 2,728 339 2,130 117 598 22 76 186

West Cameron and Sabine Pass 1,181 167 11,662 154 10,584 13 1,078 120 2 269

West Delta 925 982 4,201 961 4,046 21 155 25 4 62

Central Slope (Other)** 0000000 000

Central Planning Area Subtotal 11,234 9,848 74,646 7,253 66,056 2,595 8,590 904 786 3,080

Eastern Planning Area Subtotal*** 12 1 542 0 88 1 454 12 0 212

GOM Total 13,691 10,081 94,159 7,438 83,694 2,643 10,465 1,154 827 4,174

 *Western Slope (Other) includes Corpus Christi, Keathley Canyon, and Port Isabel.

 **Central Slope (Other) includes Lund and Walker Ridge.

 ***Eastern Planning Area includes DeSoto Canyon, Destin Dome, Lloyd Ridge, and others.

 production proved Unproved

 reserves through 2005 reserves reserves Area

Number of 

proved 

reservoirs

Number of 

unproved 

reservoirs

(Reserves: oil expressed in millions of barrels at 60 oF and 1 atmosphere, gas in billions of cubic feet at 60 oF and 15.025 psia.)

 Cumulative Remaining

 Proved

Table 3d. Estimated oil and gas reserves for Pre-Miocene reservoirs in 23 proved and 3 unproved fields 

by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005. 

 Oil Gas Oil Gas Oil Gas Oil Gas

Western Planning Area

Mustang Island and N. & S. Padre 8 0 33 0 20 0 13 0 0 0

Western Slope (Other)* 0 000000 000

Western Planning Area Subtotal 8 0 33 0 20 0 13 0 0 0

Central Planning Area

Main Pass and Breton Sound 1000000 000

Mobile 21 0 1,773 0 1,445 0 328 4 0 126

Viosca Knoll (Shelf) 14 0 296 0 243 0 53 5 0 17

Central Slope (Other)** 0000000 000

Central Planning Area Subtotal 36 0 2,069 0 1,688 0 381 9 0 143

Eastern Planning Area Subtotal*** 0 0 0 0 0 0 0 1 0 491

GOM Total 44 0 2,102 0 1,708 0 394 10 0 634

 *Western Slope (Other) includes Corpus Christi, Keathley Canyon, and Port Isabel.

 **Central Slope (Other) includes Lund and Walker Ridge.

 ***Eastern Planning Area includes DeSoto Canyon, Destin Dome, Lloyd Ridge, and others.

 production proved Unproved

 reserves through 2005 reserves reserves Area

Number of 

proved 

reservoirs

Number of 

unproved 

reservoirs

(Reserves: oil expressed in millions of barrels at 60 oF and 1 atmosphere, gas in billions of cubic feet at 60 oF and 15.025 psia.)

 Cumulative Remaining

 Proved
17

Figure 12. Miocene reserves trend. 

Figure 13. Pre-Miocene reserves trend. 
18

Table 3e. Estimated oil and gas reserves for reservoirs that Span Ages in 5 proved and 16 unproved fields 

by area, Gulf of Mexico, Outer Continental Shelf, December 31, 2005. 

 Oil Gas Oil Gas Oil Gas Oil Gas

Western Planning Area

Alaminos Canyon 0 0 0 0 0 0 0 17 373 549

Western Slope (Other)* 0 000000 184

Western Planning Area Subtotal 0 0 0 0 0 0 0 18 381 553

Central Planning Area

Atwater Valley 18 48 43 0 0 48 43 5 55 80

Green Canyon 25 1,270 755 12 3 1,258 752 20 658 346

Central Slope (Other)** 0 0 0 0 0 0 0 10 851 159

Central Planning Area Subtotal 43 1,318 798 12 3 1,306 795 35 1,564 585

Eastern Planning Area Subtotal*** 0 0 0 0 0 0 0 0 0 0

GOM Total 43 1,318 798 12 3 1,306 795 53 1,945 1,138

 *Western Slope (Other) includes Corpus Christi, Keathley Canyon, and Port Isabel.

 **Central Slope (Other) includes Lund and Walker Ridge.

 ***Eastern Planning Area includes DeSoto Canyon, Destin Dome, Lloyd Ridge, and others.

Area

Number of 

proved 

reservoirs

Number of 

unproved 

reservoirs

(Reserves: oil expressed in millions of barrels at 60 oF and 1 atmosphere, gas in billions of cubic feet at 60 oF and 15.025 psia.)

 Cumulative Remaining

 Proved production proved Unproved

 reserves through 2005 reserves reserves

Figure 14 shows the percentages of reserves and production data by geologic age. This figure matches the 

chronostratigraphy by the MMS in the abbreviated Gulf of Mexico biostratigraphic chart presented in Figure 9. This 

figure exhibits that Miocene is the predominant reserves trend in the Gulf of Mexico, with the largest percentage of 

proved reserves, cumulative production, and remaining proved reserves. 

7%

16% 8% 16%

4%

35%

31% 41% 32%

20%

26%

52% 51% 51%

58%

7%

25%

9%

51%

51%

1% 1%

2%

5%

0%

20%

40%

60%

80%

100%

Oil Gas Oil Gas Oil Gas

Percent barrels of oil 

equivalent (BOE)

PLEISTOCENE PLIOCENE MIOCENE

PRE-MIOCENE SPAN AGES

Proved

Reserves

Cumulative 

Production

Remaining 

Proved Reserves

Figure 14. Distribution of reserves and production data by geologic age. 
19

Historical Exploration and Discovery Pattern and Trends

In large part, the following section was taken from An Exploration and Discovery Model: a Historic Perspective - 

Gulf of Mexico Outer Continental Shelf by Gary Lore (1994). The information presented has been updated to 

reflect the current database. 

It is informative to review the historic exploration and development activities that resulted in the world-class 

hydrocarbon-producing basin that is the Gulf of Mexico. Each of the decades of activity will be examined by reviewing 

the status of exploration and development activity and the number of fields and quantities of proved reserves 

discovered during each decade. The discovery year is defined as the year in which the first well encountering 

significant hydrocarbons reached total depth. This date may differ from the year in which the field discovery was 

announced. 

Figures 15-20 depict locations of proved fields by decade with bar heights proportional to total proved reserves in 

barrels of oil equivalent (BOE). Figure 15 shows the locations of the proved fields discovered prior to December 31, 

1959. As expected, initial development was in shallower, nearshore waters concentrated mainly in the areas off 

central and western Louisiana. This primarily reflected the gradual extension of existing inland drilling and 

development technologies into the open-water marine environments, and the infancy of marine seismic acquisition 

activities. Early exploratory drilling in very shallow water on the shelf utilized barges and platforms. The mid-1950’s 

witnessed the introduction of submersible and jack-up drilling rigs. During this period, 272 exploratory wells were 

drilled, culminating in the discovery of 68 proved fields. It was also during this period that 5 of the top 10 fields in the 

Gulf of Mexico, based on proved reserves, were discovered, the largest being West Delta 30. 

Figure 15. Location of proved fields discovered 1947-1959, Gulf of Mexico OCS. 

Figure 16 shows the location of the proved fields discovered in the 1960’s. These discoveries were still concentrated 

offshore central and western Louisiana. Though still confined to the shelf (650 ft or less), field discoveries advanced 

seaward into deeper waters. During this decade, 2,123 exploratory wells were drilled and 148 proved fields 

discovered. The thirteenth largest proved field in the Gulf of Mexico, Ship Shoal 208, was discovered in the sixties. 
20

Figure 16. Location of proved fields discovered 1960-1969, Gulf of Mexico OCS. 

Figure 17 shows the location of the proved fields discovered in the 1970’s. This period reflects continued drilling and 

development on the shelf, with an increase in field discoveries on the seaward portion of the shelf, predominantly of 

Pleistocene age. The introduction of global positioning systems, used on drillships and semi-submersible drilling rigs, 

further opened up deepwater exploration. Frontier drilling on the shelf-slope margin led to discoveries of new fields in 

what has been termed the Flexure Trend. During this decade, 3,033 exploratory wells were drilled, resulting in the 

discovery of 282 proved fields. The second largest field in the Gulf of Mexico, Eugene Island 330, was discovered in 

246 ft of water during this decade. Another significant field discovery was Mississippi Canyon 194, the first field in 

over 1,000 ft of water. 

During the 1980’s, development activities occurred over practically the entire central and western Gulf of Mexico 

shelf, as well as on the upper slope, as can be seen in Figure 18. In addition, the first Norphlet fields and a Miocene 

shallow bright spot play were discovered in the eastern Central Gulf of Mexico planning area. Exploratory drilling had 

now reached water depths beyond 6,000 ft. In this decade, 4,277 exploration wells were drilled, resulting in the 

discovery of 370 proved fields (30 were discovered in water depths greater than 1,000 ft). The largest field in the Gulf 

of Mexico, MC807, was discovered during this time period. 

For the 1990’s (Figure 19), 4,041 exploration wells were drilled, resulting in the discovery of 221 proved fields (52 

were discovered in water depths greater than 1,000 ft). The 1990’s saw the refinement and reduction in cost of 

tension leg platform design and a much expanded use of subsea completions. Available production histories have 

documented high production rates for deepwater fields. The expanding use of horizontal drilling increased 

productivity of specific reservoirs. Computer workstation technology using three-dimensional seismic data sets 

allowed for reduced risk and greater geologic assurance in exploration and field development, as well as exploration 

of new plays, such as the subsalt play. The third largest field in the Gulf of Mexico, MC778, was discovered in the 

nineties. 

From 2000 to 2005 (Figure 20), 2,233 exploration wells were drilled, resulting in the discovery of 107 proved fields. 

Nearly 32 percent of those fields were in greater than 1,000 ft of water. Reserve estimates for field discoveries during 

this period may have significant increases because of increased well control, reservoir management, and in-field 

exploration. MC776, the tenth largest field in the Gulf of Mexico, was discovered during this time period. 
21

Figure 17. Location of proved fields discovered 1970-1979, Gulf of Mexico OCS. 

Figure 18. Location of proved fields discovered 1980-1989, Gulf of Mexico OCS. 
22

Figure 19. Location of proved fields discovered 1990-1999, Gulf of Mexico OCS. 

Figure 20. Location of proved fields discovered 2000-2005, Gulf of Mexico OCS. 
23

Figure 21 shows annual field discoveries by geologic age for the 1,196 proved fields. Figure 22 shows annual 

discoveries of proved reserves by geologic age for the 1,196 proved fields. These two figures show several trends 

over the last 50 years. From the mid-1940’s through the 1960’s, the largest number of fields discovered were of 

Miocene age and these fields contributed the largest reserves additions. This trend reflects a continuation of the 

nearshore operating environment. The decade of the 1970’s saw a large peak in the discovery of Pleistocene and 

Pliocene fields and proved reserves. Technological advances in seismic data and deeper drilling accounted for the 

resurgence of Miocene field discoveries and reserve additions in the decade of the 1980’s. This decade also saw the 

first Jurassic Norphlet discoveries. The decline in the number of fields discovered from 2001 to 2005 may in part be 

due to changes in industry exploration trends and active hurricane seasons. Large Miocene and Pliocene discoveries 

in the late 1990’s will play a major role in future production. The MMS OCS Report MMS 2008-013, Deepwater Gulf 

of Mexico 2008: America’s Offshore Energy Future, available from MMS’s Gulf of Mexico Region Internet Web 

site, provides detailed information on deepwater activities. 

0

5

10

15

20

25

30

35

40

45

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Number of Fields

0

5

10

15

20

25

30

35

40

45

Number of Fields

Pleistocene

Pliocene

Miocene

Pre-Miocene

Figure 21. Annual number of field discoveries by geologic age, 1,196 proved fields. 
24

0

500

1,000

1,500

2,000

2,500

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

0

500

1,000

1,500

2,000

2,500

Pleistocene

Pliocene

Miocene

Pre-Miocene

Proved Reserves, 

Million Barrels of Oil Equivalent

Proved Reserves, 

Million Barrels of Oil Equivalent

Figure 22. Annual discoveries of proved reserves by geologic age, 1,196 proved fields. 

Field-Size Distribution

Reserve sizes are expressed in terms of barrels of oil equivalent (BOE). Gas reserves are converted to BOE and 

added to the liquid reserves for the convenience of comparison. The conversion factor of 5,620 standard cubic feet of 

gas equals 1 BOE is based on the average heating values of domestic hydrocarbons. A geometric progression, 

developed by the USGS (Attanasi, 1998), was selected for field-size distribution ranges (Figure 23). 

In this report, fields are classified as either oil or gas; some fields do produce both products, making a field type 

determination difficult. Generally, fields with a gas/oil ratio (GOR) less than 9,700 standard cubic feet per stock tank 

barrel (SCF/STB) are classified as oil. 
25

Class Deposit-size 

range* Class Deposit-size 

range* Class Deposit-size 

range*

1 0.031 - 0.062 10 16 - 32 18 4,096 - 8,192

2 0.062 - 0.125 11 32 -64 19 8,192 - 16,384

3 0.125 - 0.25 12 64 - 128 20 16,384 - 32,768

4 0.25 - 0.50 13 128 - 256 21 32,768 - 65,536

5 0.50 - 1.00 14 256 - 512 22 65,536 - 131,072

6 1 - 2 15 512 - 1,024 23 131,072 - 262,144

7 2 - 4 16 1,024 - 2,048 24 262,144 - 524,288

8 4 - 8 17 2,048 - 4,096 25 524,288 - 1,048,576

9 8 - 16 *M illion Barrels of Oil Equivalent (M M BOE)

Figure 23. Description of deposit-size classes. 

The field-size distribution based on proved reserves for 1,196 proved fields is shown in Figure 24(a). Of the 1,196 

proved oil and gas fields, there are 223 proved oil fields represented in Figure 25(a) and 973 gas fields shown in 

Figure 26(a). The Western Gulf of Mexico field-size distributions are displayed on Figures 24(b), 25(b), and 26(b). 

Figures 24(c), 25(c), and 26(c) present the Central Gulf of Mexico field-size distributions of proved reserves including 

one field in the Eastern Gulf of Mexico. The field-size distribution, derived from unproved reserves for 56 unproved 

fields, is shown in Figure 27(a). There are 32 unproved oil fields in Figure 27(b) and 24 unproved gas fields in 

Figure 27(c). All unproved active fields were studied. 

Analysis of the 1,196 proved oil and gas fields indicates that the Gulf of Mexico is historically a gas-prone basin. 

Figure 28 presents the median (exceeded by 50%) and the mean (arithmetic average) reserves from the field-size 

distributions. This figure also provides information on the largest two field-size ranges from Figures 24-27. The GOR 

of the 223 proved oil fields is 2,581 SCF/STB. The GOR of the 32 unproved oil fields is 786 SCF/STB. The mean 

yield (condensate divided by gas) for the 973 proved gas fields is 22.8 barrels of condensate per million cubic feet 

(MMcf) of gas. The mean yield of the 24 unproved gas fields is 15.7 barrels of condensate per MMcf. 
26

0

8 11 14

35

68

119

132

147148150158

98

69

28

10 1

0

40

80

120

160

200

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

40

80

120

160

200

Number of Fields

( a ) GOM

Total: 52,147 MMBOE

Median: 10.8 MMBOE

Mean: 43.6 MMBOE

Largest 11 Fields 

15% of Reserves

03 2 2 7

23

35 46 52 48 39 50

17 8 3

0

40

80

120

160

200

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

40

80

120

160

200

Number of Fields

( b ) Western GOM Total: 7,687 MMBOE

Median: 7.7 MMBOE

Mean: 22.9 MMBOE

05 9 12

28

45

84 86 95 100111108

81

61

25

10 1

0

40

80

120

160

200

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

40

80

120

160

200

Number of Fields

( c ) Central and 

Eastern GOM

Total: 44,460 MMBOE

Median: 12.8 MMBOE

Mean: 51.6 MMBOE

Figure 24. Field-size distribution of proved fields: (a) 1,196 fields, GOM; (b) 335 fields, Western GOM; 

(c) 861 fields, Central and Eastern GOM. 
27

4

1 2 4 4

12 15

20

31

34

38 35

14

8

1

0

10

20

30

40

50

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

10

20

30

40

50

Number of Fields

( a ) GOM

Total: 24,265 MMBOE

Median: 49.7 MMBOE

Mean: 108.8 MMBOE

Largest 9

Fields 28%

of Reserves

0 1 3 1 3

7 6 6

1 2

0

10

20

30

40

50

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of FieldsNumber of Fields

( b ) Western GOM

Total: 1,736MMBOE

Median: 28.4 MMBOE

Mean: 57.9 MMBOE

0

4

1 2 3 4

9

14 17

24

28

32 34

12

8

1

0

10

20

30

40

50

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

10

20

30

40

50

Number of Fields

( c ) Central GOM

Total: 22,529 MMBOE

Median: 55.4 MMBOE

Mean: 116.7 MMBOE

Figure 25. Field-size distribution of proved oil fields: (a) 223 fields GOM; (b) 30 fields, Western GOM; 

(c) 193 fields, Central and Eastern GOM. 
28

0

8 7 13

33

64

115120132128119124

60

34

14 2

0

40

80

120

160

200

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

40

80

120

160

200

Number of Fields

( a ) GOM Total: 27,882 MMBOE

Median: 7.6 MMBOE

Mean: 28.7 MMBOE

Largest 16

Fields 20%

of Reserves

03 2 2 7

22

35 43 51 45

32 44

11 7 1

0

40

80

120

160

200

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

40

80

120

160

200

Number of Fields

( b ) Western GOM Total: 5,951 MMBOE

Median: 6.9 MMBOE

Mean: 19.5 MMBOE

05 5 11

26

42

80 77 81 83 87 80

49

27

13 2

0

40

80

120

160

200

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Proved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

40

80

120

160

200

Number of Fields

( c ) Central and 

Eastern GOM

Total: 21,931 MMBOE

Median: 8.7 MMBOE

Mean: 32.8 MMBOE

Figure 26. Field-size distribution of proved gas fields: (a) 973 fields, GOM; (b) 305 fields, Western GOM; 

(c) 668 fields, Central and Eastern GOM. 
29

0

2 1 1

3

1

10

4

10 10

3 4 4

2 1

0

10

20

30

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Unproved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

10

20

30

Number of Fields

( a ) Unproved, GOM

Total: 2,815 MMBOE

Median: 10.2 MMBOE

Mean: 50.3 MMBOE

Largest 3

Fields 39%

of Reserves

0

2 3

8

6

3 3 4

2 1

0

10

20

30

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Unproved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

10

20

30

Number of Fields

( b ) Unproved oil, GOM

Total: 2,589 MMBOE

Median: 26.5 MMBOE

Mean: 80.9 MMBOE

Largest 3

Fields 43%

of Reserves

0

2 1 1

3

1

8

1 2

4

1

0

10

20

30

< 0.062

 < 0.125

< 0.25

< 0.5

< 1< 2< 4< 8

< 16< 32< 64

< 128< 256< 512

< 1,024< 2,048< 4,096< 8,192

Unproved Reserves, Million Barrels of Oil Equivalent

Number of Fields

0

10

20

30

Number of Fields

( c ) Unproved gas, GOM

Total: 225 MMBOE

Median: 3.1 MMBOE

Mean: 9.4 MMBOE Largest

Field 39%

of Reserves

Figure 27. Field-size distribution of unproved fields: (a) 56 fields, GOM; (b) 32 oil fields, GOM; 

(c) 24 gas fields, GOM. 
30

Figure 28. GOM field-size distribution. 

Figure 29 shows the cumulative percent distribution of proved reserves in billion barrels of oil equivalent (BBOE), by 

field rank. All 1,196 proved fields in the Gulf of Mexico OCS are included in this figure. A characteristic often 

observed in hydrocarbon-producing basins is a rapid drop-off in size from that of largest known field to smallest. 

Twenty-five percent of the proved reserves are contained in the 24 largest fields. Fifty percent of the proved reserves 

are contained in the 83 largest fields. Ninety percent of the proved reserves are contained in the 411 largest fields. 

Figure 30 shows the distribution of the number of fields and proved reserves by water depth. A field’s water depth is 

determined by averaging the water depth of the wells drilled in the field. The water depth ranges used in this figure, 

651-1,300 ft, 1,301-2,600 ft, and greater than 2,600 ft, closely approximate the 200-400 meter, 401-800 meter, and 

greater than 800 meter water depths used in the OCS Deepwater Royalty Relief Act of 1995 (DWRRA). Proved 

reserves, reported in MMBOE, are associated with the 1,196 proved fields. The 56 unproved active fields are 

presented to show recent activity. Fifty-seven percent of the proved reserves in the Gulf of Mexico are located in less 

than 200 ft of water. The shelf, generally considered as less than 650 ft of water, accounts for 78 percent of the 

proved reserves. Development beyond the shelf, generally considered greater than 650 ft of water, reflects a sizeable 

amount of proved reserves associated with a few fields. The mean proved reserves per proved field in the Gulf of 

Mexico is 43.6 MMBOE. For water depths less than 651 ft, it is 39.0 MMBOE; for 651-1,300 ft, it is 37.4 MMBOE; for 

1,301-2,600 ft, it is 47.2 MMBOE; and greater than 2,600 ft, it is 110.3 MMBOE. 

Number Reserves

1,196 Proved Fig. 24a 10.8 43.6 11 15%

223 Proved Oil Fig. 25a 49.7 108.8 9 28%

973 Proved Gas Fig. 26a 7.6 28.7 16 20%

56 Unproved Fig. 27a 10.2 50.3 3 39%

32 Unproved Oil Fig. 27b 26.5 80.9 3 43%

24 Unproved Gas Fig. 27c 3.1 9.4 1 39%

* Million barrels of oil equivalent (MMBOE)

Description of Largest Fields

Fields

Figure 

Number Median* Mean*
31

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900 1,0001,100

Number of Fields, Rank Order

Proved Reserves, 

Billion Barrels of Oil Equivalent

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Cumulative Percent

90% of the proved reserves are in the 

411 largest fields

50% of the proved reserves are in the 

83 largest fields

25% of the proved reserves are in the 

24 largest fields

Figure 29. Cumulative percent total reserves versus rank order of field size for 1,196 proved fields. 10,877 8,562 10,221 1,608 1,557 8,275 608 629 560 651 204412 5,317

017

90

12

44

2,661

11,047

198

294

296

257

43

33

75

11

6

33

4

39

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

0-50 51-100 101-200 201-650 651-1,300 1,301-2,600 >2,600

Water Depth, Feet

0

50

100

150

200

250

300

350

400

Number of Fields

Proved reserves 

(52,147 MMBOE)

Number of proved 

fields (1,196)

Remaining proved 

reserves (8.382 MMBOE)

Number of unproved 

fields (57)

Unproved reserves 

(2.815 MMBOE)

Reserves, 

Million Barrels of Oil Equivalent

10,877

8,562

10,221

1,608

1,557

8,275

608

629

560

651

204

412

5,317

017

90

12

44

2,661

11,047

198

294

296

257

43

33

75

11

6

33

4

39

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

0-50 51-100 101-200 201-650 651-1,300 1,301-2,600 >2,600

Water Depth, Feet

0

50

100

150

200

250

300

350

400

Number of Fields

Proved reserves 

(52,147 MMBOE)

Number of proved 

fields (1,196)

Remaining proved 

reserves (8.382 MMBOE)

Number of unproved 

fields (57)

Unproved reserves 

(2.815 MMBOE)

Proved reserves 

(52,147 MMBOE)

Number of proved 

fields (1,196)

Remaining proved 

reserves (8.382 MMBOE)

Number of unproved 

fields (57)

Unproved reserves 

(2.815 MMBOE)

Reserves, 

Million Barrels of Oil Equivalent

Figure 30. Field and reserves distribution by water depth. (Totals are in parentheses.) 
32

Figure 31 shows the largest 20 fields ranked in order by remaining proved reserves. Eighteen of the twenty top fields 

lie in water depths of greater than 1,300 ft and account for 54 percent of the remaining proved reserves in the Gulf of 

Mexico. 

Estimates of proved reserves beyond the shelf are increasing. This trend is expected to continue in the future 

because of additional exploration and development. Of the 151 proved fields in water depths greater than 650 ft, 118 

are producing, 12 are depleted, and 21 have yet to produce. There are 46 unproved active fields in water depths 

greater than 650 ft. These fields contain 2,717 MMBOE, representing 97 percent of the Gulf of Mexico total of 

estimated unproved reserves. 

Exploration and development of the deepwater Gulf of Mexico has accelerated with technological advances, 

expansion of the infrastructure, and the enactment of the DWRRA. This has given industry the incentive to explore 

and produce deepwater resources as these activities continue to increase in importance to the Nation’s energy 

supply. 

0

100

200

300

400

500

600

700

800

900

1,000

1,100

1,200

MC778MC807

GC743

MC776

GC640GC644GC826

MC696

EB602

GC562

MC383

GB783

MC773MC084MC582

EW873

GC158

AT575

VK786DC621

0

100

200

300

400

500

600

700

800

900

1,000

1,100

1,200

> 1,300 ft.

651 - 1,300 ft.

0 - 650 ft.

89

Field water depth

3

61

5

1

13

28

34

107 57

134 119 40 144 182 177

120

204 76 95 170

745

210

690

623

527

450

236

158 134

104 81 76 73 56

109

55 55 55 60

Field Size Rank by

Proved Reserves

Remaining Proved Reserves

Remaining Proved Reserves, 

Million Barrels of Oil Equivalent

Remaining Proved Reserves, 

Million Barrels of Oil Equivalent

Figure 31. Largest 20 fields ranked by remaining proved reserves. 

Table 4 lists the 50 largest proved fields ranked by proved reserves expressed in BOE. Rank, field name, new fields, 

discovery year, water depth, field classification, field type, field GOR, proved reserves, cumulative production through 

2005, and remaining proved reserves are presented. A complete listing of all 1,196 proved fields, ranked by proved 

reserves, is available from MMS’s Gulf of Mexico Region Internet Web site or by contacting the MMS at 1-800-200-

GULF. New fields proved in 2005 are identified with an asterisk in the column labeled “New field.” Unproved fields 

reserve data will not be listed. For proved fields not yet qualified, the field names are replaced with two asterisks to 

preserve the proprietary nature of the data. 
33

Table 4. Gulf of Mexico proved fields by rank order, based on proved BOE reserves, top 50 fields. 

 Oil Gas BOE Oil Gas BOE Oil Gas BOE

 (SCF/STB) (MMbbl) (Bcf) (MMbbl) (MMbbl) (Bcf) (MMbbl) (MMbbl) (Bcf) (MMbbl)

1 MC807 1989 3,367 PDP O 1,444 1,208.2 1,745.2 1,518.7 673.1 875.7 828.9 535.1 869.5 689.8

2 EI330 1971 247 PDP O 4,257 425.4 1,811.0 747.6 419.4 1,800.7 739.8 6.0 10.4 7.9

3 MC778 1999 6,065 PU O 794 653.1 518.3 745.3 0.0 0.0 0.0 653.1 518.3 745.3

4 WD030 1949 48 PDP O 1,567 570.6 894.3 729.8 558.0 836.0 706.8 12.6 58.3 23.0

5 GI043 1956 139 PDP O 4,309 372.2 1,604.0 657.6 360.4 1,534.4 633.4 11.8 69.6 24.2

6 BM002 1949 50 PDP O 1,034 526.9 545.1 623.9 520.6 534.6 615.8 6.3 10.6 8.1

7 GC743 * 1998 6,618 PU O 647 558.9 361.6 623.2 0.0 0.0 0.0 558.9 361.6 623.2

8 TS000 1958 13 PDP G 80,477 40.3 3,247.0 618.1 36.9 3,139.9 595.6 3.4 107.0 22.4

9 VR014 1956 26 PDP G 64,284 48.1 3,093.7 598.6 47.8 3,051.1 590.7 0.3 42.6 7.9

10 MC776 2000 5,664 PU O 1,113 440.0 489.7 527.2 0.0 0.0 0.0 440.0 489.7 527.2

11 MP041 1956 42 PDP O 5,685 262.0 1,489.3 527.0 249.7 1,437.2 505.4 12.3 52.0 21.5

12 VR039 1948 38 PDP G 81,259 31.7 2,578.4 490.5 31.1 2,539.6 483.0 0.7 38.8 7.6

13 SS208 1960 102 PDP O 6,327 221.3 1,400.4 470.5 215.2 1,333.6 452.5 6.1 66.8 18.0

14 GC640 * 2002 4,152 PDN O 487 414.0 201.6 449.9 0.0 0.0 0.0 414.0 201.6 449.9

15 WD073 1962 177 PDP O 2,460 264.4 650.3 380.1 258.5 630.4 370.6 5.9 19.9 9.5

16 GB426 1987 2,859 PDP O 3,601 228.1 821.3 374.2 206.3 741.4 338.3 21.7 79.9 36.0

17 GI016 1948 54 PDP O 1,271 303.0 384.9 371.5 297.8 376.4 364.8 5.1 8.6 6.7

18 EI238 1964 146 PDP G 16,144 91.9 1,484.2 356.0 84.1 1,404.0 334.0 7.8 80.1 22.1

19 SP061 1967 220 PDP O 1,930 263.8 509.2 354.4 258.1 502.5 347.6 5.6 6.7 6.8

20 ST172 1962 98 PDP G 154,010 12.4 1,908.6 352.0 11.2 1,822.2 335.5 1.2 86.5 16.5

21 ST021 1957 46 PDP O 1,769 260.5 461.0 342.5 243.8 391.6 313.5 16.7 69.3 29.0

22 SP089 1969 423 PDP O 4,411 190.7 841.5 340.5 187.8 814.5 332.7 2.9 26.9 7.7

23 WC180 1961 48 PDP G 142,477 12.9 1,831.2 338.7 12.7 1,772.1 328.0 0.2 59.1 10.7

24 ST176 1963 126 PDP G 14,564 90.2 1,313.5 323.9 80.6 1,152.8 285.7 9.6 160.7 38.2

25 SM048 1961 100 PDP G 55,446 28.8 1,595.4 312.7 27.7 1,507.5 296.0 1.1 87.9 16.7

26 MC194 1975 1,018 PDP O 4,158 178.1 740.4 309.8 176.1 734.1 306.7 1.9 6.3 3.1

27 SS169 1960 63 PDP O 5,350 158.6 848.8 309.7 152.1 812.4 296.7 6.5 36.4 13.0

28 EI292 1964 223 PDP G 84,574 19.1 1,617.2 306.9 18.2 1,606.8 304.1 0.9 10.4 2.7

29 EC271 1971 171 PDP G 18,959 69.8 1,323.0 305.2 67.5 1,308.5 300.3 2.3 14.5 4.9

30 EC064 1957 50 PDP G 56,952 27.3 1,552.9 303.6 26.6 1,535.3 299.8 0.7 17.6 3.8

31 SS176 1956 100 PDP G 19,793 65.3 1,293.3 295.4 62.2 1,252.1 285.0 3.1 41.2 10.4

32 SP027 1954 65 PDP O 5,230 151.1 790.1 291.7 149.6 760.8 285.0 1.4 29.3 6.6

33 WC587 1971 211 PDP G 117,641 13.1 1,544.1 287.9 12.7 1,525.5 284.1 0.4 18.7 3.7

34 ST135 1956 130 PDP O 3,523 172.0 605.9 279.8 165.0 571.4 266.6 7.0 34.5 13.2

35 EI296 1971 214 PDP G 69,940 20.3 1,420.8 273.1 20.3 1,410.3 271.2 0.0 10.4 1.9

36 WD079 1966 124 PDP O 3,812 162.3 618.8 272.4 160.2 608.2 268.4 2.1 10.7 4.0

37 WC192 1954 57 PDP G 60,139 23.1 1,387.9 270.0 22.2 1,351.0 262.6 0.8 36.9 7.4

38 MI623 1980 82 PDP G 98,861 14.3 1,411.7 265.5 13.3 1,318.0 247.8 1.0 93.7 17.7

39 HI573A 1973 342 PDP O 7,811 109.4 854.8 261.5 106.6 848.5 257.6 2.8 6.3 3.9

40 GC644 1999 4,339 PDP O 1,234 209.6 258.7 255.6 16.6 19.0 20.0 192.9 239.6 235.6

41 GI047 1955 89 PDP O 3,575 148.3 526.5 242.0 143.5 512.8 234.7 4.8 13.6 7.2

42 SM023 1960 82 PDP G 38,919 29.8 1,160.0 236.2 29.5 1,140.6 232.4 0.3 19.4 3.8

43 SM130 1973 214 PDP O 1,356 189.4 256.8 235.1 181.9 243.9 225.3 7.5 12.9 9.8

44 SP078 1972 203 PDP G 11,706 76.2 891.9 234.9 71.7 876.2 227.6 4.5 15.7 7.3

45 VR076 1949 31 PDP G 132,811 9.4 1,251.2 232.0 7.0 1,155.3 212.6 2.4 95.9 19.4

46 GC244 1994 2,678 PDP O 2,005 170.3 341.5 231.0 157.4 314.7 213.4 12.9 26.8 17.7

47 PL020 1951 33 PDP O 5,781 113.5 656.2 230.3 106.6 597.0 212.8 6.9 59.1 17.5

48 ST052 1948 58 PDP O 5,893 111.9 659.2 229.2 94.2 558.3 193.5 17.7 100.9 35.6

49 VK956 1985 3,239 PDP O 9,176 86.3 791.7 227.1 76.2 649.9 191.8 10.1 141.8 35.3

50 SM066 1963 124 PDP G 254,870 4.9 1,242.3 225.9 4.8 1,216.2 221.2 0.1 26.1 4.7

Cumulative production 

through 2005

Remaining 

proved reserves Field 

class

Water 

depth 

(feet)

Field 

type

Proved 

reserves Field 

GOR 

Rank Field 

name

New 

field

Disc 

year

 (For proved fields not qualified in 2005 the names are replaced with asterisks to preserve the proprietary nature of the data.)

 (Field class: PDP - Proved Developed Producing; PDN - Proved Developed Non-Producing; PU - Proved Undeveloped)

 (Field type: O - Oil; G - Gas)
34

Reservoir-Size Distribution

The size distributions of the proved reservoirs are shown in Figures 32, 33, and 34. The size ranges are based on 

proved reserves and are presented on a geometrically progressing, horizontal scale. These sizes correspond with 

the USGS deposit-size ranges shown in Figure 23 with a modification to reflect small reservoirs in a finer distribution. 

For Figures 33 and 34, the proved reserves are presented in MMbbl and Bcf, respectively. The number of reservoirs 

in each size grouping, shown as percentages of the total, is presented on a linear vertical scale. For the combination 

reservoirs (saturated oil rims with associated gas caps), shown in Figure 32, gas is converted to BOE and added to 

the liquid reserves. Proved uneconomic reservoirs are excluded from these distributions, but are included in the Table 

3 series. 

Figure 32 shows the reservoir-size distribution, on the basis of proved BOE, for 2,223 proved combination reservoirs. 

The median is 0.9 MMBOE and the mean is 2.9 MMBOE. The GOR for the oil portion of the reservoirs is 1,167 

SCF/STB, and the yield for the gas cap is 21.4 barrels of condensate per MMcf of gas. 

Figure 33 shows the reservoir-size distribution, on the basis of proved oil, for 7,906 proved undersaturated oil 

reservoirs. The median is 0.3 MMbbl, the mean is 1.8 MMbbl, and the GOR is 1,221 SCF/STB. 

Figure 34 shows the reservoir-size distribution, on the basis of proved gas, for 17,003 gas reservoirs. The median is 

2.3 billion cubic feet (Bcf) of gas, the mean is 8.9 Bcf, and the yield is 12.0 barrels of condensate per MMcf of gas. 

 

0.1 0.2 0.3 0.7 1.2

2.2

3.6

6.7

8.4

13.3 13.9

8.6

4.4

2.1

0.9 0.3

16.5

16.7

0

5

10

15

20

25

0.000- 0.001

0.001 - 0.0020.002 - 0.0040.004 - 0.0080.008 - 0.0160.016 - 0.0310.031 - 0.0620.062 - 0.1250.125 - 0.250

0.25 - 0.500.50 - 1.00

1 - 22 - 44 - 8

8 - 16

16 - 3232 - 64

64 - 128

128 - 256

Proved Reserves, Million Barrels of Oil Equivalent

Percent of Reservoirs

0

5

10

15

20

25

Percent of Reservoirs

0.9 MMBOE

2.9 MMBOE

Median :

Mean :

Yield : 21.4 bbl/MMcf

GOR: 1,167 SCF/STB

Figure 32. Reservoir-size distribution, 2,223 proved combination reservoirs. 
35

2.2

1 1.6 2.4

3.9 4.7

7

10.3

12.8

14.6

10.9

7

4.1

2.1

0.8 0.4 0.2 0.1

13.9

0

5

10

15

20

25

0.000 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0080.008 - 0.0160.016 - 0.0310.031 - 0.0620.062 - 0.1250.125 - 0.250

0.25 - 0.500.50 - 1.00

1 - 22 - 44 - 8

8 - 16

16 - 3232 - 64

64 - 128

128 - 256

Proved Reserves, Million Barrels of Oil

Percent of Reservoirs

0

5

10

15

20

25

Percent of Reservoirs

0.3 MMbbl

1.8 MMbbl

Median :

Mean :

GOR : 1,221 SCF/STB

Figure 33. Reservoir-size distribution, 7,906 proved oil reservoirs. 

1.6 0.9 1.2 1.9 2.8

4.4

6.4

9.4

12.7

15.2

12.5

8.4

4.6

2

0.8 0.3 0.1

14.9

0

5

10

15

20

25

0.0000 - 0.00580.0058 - 0.01170.0117 - 0.02340.0234 - 0.04690.0469 - 0.09380.0938 - 0.1875

0.1875 - 0.375

0.375 - 0.750

0.75 - 1.501.50 - 3.00

3 - 6

6 - 12

12 - 2424 - 4848 - 96

96 - 192

192 - 384384 - 768

Proved Reserves, Billion Cubic Feet of Gas

Percent of Reservoirs

0

5

10

15

20

25

Percent of Reservoirs

2.3 Bcf

8.9 Bcf

Median :

Mean :

Yield : 12.0 bbl/MMcf

Figure 34. Reservoir-size distribution, 17,003 proved gas reservoirs. 
36

Production Rates and Discovery Trends

The mean daily production in the Gulf of Mexico OCS during 2005 was 1.05 MMbbl of crude oil, 0.23 MMbbl of gas 

condensate, 1.86 Bcf of casinghead gas, and 6.81 Bcf of gas-well gas. The mean GOR of oil wells was 1,769 

SCF/STB, and the mean yield from gas wells was 33.43 barrels of condensate per MMcf of gas. Monthly production 

plots and data by field are also available from MMS’s Gulf of Mexico Region Internet Web site or can be obtained on 

CD-ROM by contacting the MMS at 1-800-200-GULF. 

Figures 35 and 36 show the frequency distribution of monthly production for completions active during 2005. Since 

the number of completions within a given range changes from month to month, the completion numbers presented 

are means of the 2005 monthly completion totals for each production range. Completions off production for more 

than two days a month are not counted as continuously producing completions. 

30 5 9 15 28

70

159

260

298

220

109

53 41 44 24 29

50

32

56

95

137

166

150

90

44

23

17 11

20 11 6 14

0

100

200

300

400

500

0 16 32 64 125 250 500 1M 2M 4M 8M 16M 32M 64M 125M250M+

Monthly Production, Barrels of Oil (M=1000)

Mean Number of Completions

0

100

200

300

400

500

Mean Number of Completions

Intermittently producing

completions

Continuously producing

completions

Figure 35. Monthly distribution of oil production, 2,316 completions (1,394 continuously producing 

completions). 
37

7 2 7 11 25 49

83

129

174

213

265

233

181

93

37 20 26

45

69

97

123

142

144

124

77

45

20

7 18 4 10

23

0

100

200

300

400

500

0 125 500 2M 8M 32M 125M 500M

Monthly Production, Thousand Cubic Feet of Gas (M=1000)

Mean Number of Completions

0

100

200

300

400

500

Mean Number of Completions

Intermittently producing

completions

Continuously producing

completions

Figure 36. Monthly distribution of gas production, 2,503 completions (1,529 continuously producing 

completions). 

Figure 37 summarizes the data from monthly distributions of oil and gas production rates. The highest reported 

monthly oil production volume was from a Miocene reservoir with a subsea depth of 12,300 ft, during the month of 

November. The highest reported monthly gas production volume was from a Miocene reservoir with a subsea depth 

of 15,395 ft, during the month of May. The mean number of oil completions producing more than 1,000 bbl per day 

was 203, and the mean number of gas completions producing more than 10 MMcf per day was 133. 

2005 Oil Gas

2,316 2,503

(203 > 1,000 bbls per day) (133 > 10MMcf per day)

2,914 2,492

(June) (January)

974 38,442

(October) (January)

Mean Production Volume 13,922 bbl 82.6 MMcf

Mean Producing Rate (537 bbl per day) (3.2 MMcf per day)

Median Production Volume 2,031 bbl 24.8 MMcf

Median Producing Rate (125 bbl per day) (1.6 MMcf per day)

Highest Production Volume 934,196 bbl 4,712 MMcf

Highest Producing Rate (31,140 bbl per day) (152.0 MMcf per day)

Highest Producing Month (November) (May)

Highest Production Volume Trend (MIOCENE) (MIOCENE)

Highest Production Volume Subsea Depth (12,300 feet) (15,395 feet)

Mean Number of Producing Completions

1,529

Lowest Monthly Mean Number of Producing 

Completions

Mean Number of Continuously Producing 

Completions 1,394

Highest Monthly Mean Number of Producing 

Completions

Figure 37. Monthly completion and production data. 
38

Annual production in the Gulf of Mexico OCS is shown in Figure 38. The oil plot includes condensate and the gas 

plot includes casinghead gas. From 1986 through 1990, annual oil production declined 23 percent, which coincides 

with low world oil prices. From 1990 through 2002, annual oil production increased 106 percent, from 275 MMbbl to 

567 MMbbl, because of the addition of deepwater production. From 2002 to 2005 annual oil production decreased 18 

percent to 467 MMbbl. 

From 1990 through 1993, annual gas production declined 5 percent. From 1993 through 2001, annual gas production 

rose from 4.7 Tcf, peaking at 5.1 Tcf in 1997, a 9-percent increase. Annual gas production reached at least 5.0 Tcf 

per year from 1996 through 1999 and in 2001. From 2001 to 2005, annual gas production declined 24 percent to 3.8 

Tcf. For further analysis of the gas production decline, see the MMS OCS Report MMS 2007-020, Gulf of Mexico 

Oil and Gas Production Forecast: 2007-2016, available from MMS’s Gulf of Mexico Region Internet Web site. 

Figure 39 presents proved reserves, cumulative production, and remaining proved reserves in BBOE as of December 

31, 2005, summed according to field discovery year. Field depletion may be estimated by the relative positions of the 

cumulative production curve and the remaining proved reserves curve. For example, if the value of the remaining 

proved reserves is higher than the value of cumulative production for a given year, the aggregate depletion for fields 

discovered that year is less than 50 percent. The plot demonstrates in general that fields discovered after 1996 are 

less than 50 percent depleted. 

Figure 40 is a plot of the number of proved gas and oil fields by discovery year. The annual number of gas fields 

discovered steadily increased until 1985, declined until 1992, increased over the next five years, declined until 2000 

and generally leveled off for the next 4 years. The number of oil fields discovered has not varied much from year to 

year, never exceeding 11, and averaging only about 3.6 discoveries per year. Through 1959, 35 percent of all fields 

discovered were oil. This percentage declined steadily as more gas fields were discovered. Only 15 percent of the 

fields discovered during the 1980’s were oil fields. From 1990 through 2001, the oil fields discovered rose to 20 

percent, reflecting recent deepwater discoveries. There has only been one oil discovery per year since 2003. 

Reasons for the 2001-2005 declines exhibited in Figures 38-40 may be due in part to changes in industry exploration 

and development trends, declining mature field production, and active hurricane seasons.

0

100

200

300

400

500

600

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Oil (Million Barrels)

0

1

2

3

4

5

6

Gas (Trillion Cubic Feet)

Annual oil production

Annual gas production

Figure 38. Annual oil and gas production. 
39

0.0

1.0

2.0

3.0

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Barrels of Oil Equivalent (Billion Barrels)

0.0

1.0

2.0

3.0

Barrels of Oil Equivalent (Billion Barrels)

Proved reserves

Cumulative production

Remaining proved

reserves

Figure 39. Proved reserves and production by field discovery year. 

0

10

20

30

40

50

60

70

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Number of Fields

0

10

20

30

40

50

60

70

Number of Fields

Proved oil fields

Proved gas fields

Figure 40. Annual oil and gas field discoveries. 
40

Figure 41 presents the number of proved fields and the mean field size by field discovery year. This plot shows that 

the number of discovered fields has been decreasing from year to year since 1997, and the mean size of the fields 

has been getting smaller except for 1989 and 1996 through 1999. Except for the mean field size anomaly in 2005 

caused by an active hurricane season, the mean field size discovered is expected to increase because of reserves 

growth and additions in proved fields and reserves from unproved fields that become proved. 

Figure 42 presents the number of proved and unproved fields and the average water depth of the fields discovered in 

each year. For 2001, the mean water depth for the fields discovered peaked at nearly 3,000 ft. Since 1995, the 

mean water depth has been greater than 1,000 ft, indicating that exploration and resulting production have moved 

into deeper water. 

Figures 43 and 44 show proved oil and gas reserves and annual production by reservoir discovery year. All data 

presented in Figure 43 include crude oil and condensate, and all data presented in Figure 44 include associated and 

nonassociated gas. The year of discovery assigned to a reservoir is the year in which the first well encountering 

hydrocarbons penetrated the reservoir. For comparison with the rate of discoveries, the annual production of oil and 

gas is also shown. In four of the last ten years, annual proved reserves additions for oil have exceeded annual oil 

production, resulting in an increase in remaining proved oil reserves. Since 1984, annual gas production has 

exceeded annual proved reserve additions for gas. In general, annual proved gas reserve additions have declined 

since the early 1970’s.

Figure 45 presents the total footage drilled, the total number of wells drilled, and the number of exploratory and 

development wells drilled in the Gulf of Mexico OCS each year. All curves show a decline from 1985 to 1986 due to 

unfavorable oil and gas economics. A second decline occurred from 1990-92. Drilling increased from 1992 to 1997, 

reflecting stable energy prices and improvements in exploration and production technology. The variation in the 

number of wells drilled from 1997 to 2005 is caused in part by fluctuation in energy prices and new technologies 

defining better targets. 

Figure 46 presents the number of exploratory wells drilled each year by water depth. The plot shows the move 

toward drilling in deeper water, but also illustrates continued drilling on the shelf. From 1997 through 2005, the 

number of exploratory wells drilled in water depths between 201 and 650 ft has reduced by more than 50%. 

Exploratory wells drilled in water depths greater than 1,300 ft have doubled since 1995. This may in part be due to 

large discoveries and the availability of more deepwater drilling rigs. 
41

0.0

0.1

0.2

0.3

0.4

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Barrels of Oil Equivalent (Billion Barrels)

0

20

40

60

80

Number of Fields

Number of proved

fields

Mean field size -

proved reserves

Figure 41. Number of proved fields and mean field size by field discovery year. 

0

400

800

1,200

1,600

2,000

2,400

2,800

3,200

3,600

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Water Depth (feet)

0

20

40

60

80

Number of Fields

Number of proved and

unproved fields

Mean water depth

Figure 42. Number of proved and unproved fields and mean water depth by field discovery year. 
42

0.0

0.5

1.0

1.5

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Oil (Billion Barrels)

0.0

0.5

1.0

1.5

Oil (Billion Barrels)

Proved reserves

Annual production

Figure 43. Proved oil reserves by reservoir discovery year and annual oil production. 

0.0

2.0

4.0

6.0

8.0

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Gas (Trillion Cubic Feet)

0.0

2.0

4.0

6.0

8.0

Gas (Trillion Cubic Feet)

Proved reserves

Annual production

Figure 44. Proved gas reserves by reservoir discovery year and annual gas production. 
43

0

250

500

750

1,000

1,250

1,500

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Number of Wells

0

2

4

6

8

10

12

14

16

18

Total Footage (Million Feet)

Total wells

Development wells

Exploratory wells

Total footage

Figure 45. Wells and footage drilled. 

0

50

100

150

200

250

300

350

400

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Number of Wells

0

50

100

150

200

250

300

350

400

Number of Wells

Water depth 0-200 ft

Water depth 201-650 ft

Water depth 651-1,300 ft

Water depth > 1,300 ft

Figure 46. Number of exploratory wells drilled by water depth. 
44

Summary and Comparison of Proved Reserves

 

A summary of the proved reserve estimates for 2005 and a comparison with estimates from the previous year’s report 

(December 31, 2004) are shown in Table 5. There were 13 proved fields added during 2005 (1 oil field and 12 gas 

fields), which are summarized and tabulated as increases to proved reserves. Note that all 13 of the proved fields 

added were discovered prior to 2005. 

Proved reserve estimates are revised as additional wells are drilled and new leases are added to existing fields, and 

as reservoirs are depleted and leases relinquished. Complete reevaluations of existing field studies are conducted on 

the basis of changes in field development and/or production history. Revisions of proved reserves are summarized 

and presented as changes in Table 5. Based on periodic reviews and revisions of field studies conducted since the 

2004 report, the revisions for proved oil and gas reserves have resulted in a net increase. A net change in the proved 

oil and gas reserves is a result of combining the discoveries and the revisions. 

Table 5 demonstrates that the 2005 proved oil and gas discoveries and field revisions exceeded oil and gas 

production primarily because of lost production as a result of an active hurricane season. The remaining proved 

reserves increased for oil and gas since the 2004 report. 

Table 5. Summary and comparison of proved oil and gas reserves as of December 31, 2004, 

and December 31, 2005. 

Proved reserves:

18.96 178.4 

Discoveries 0.06 0.2

Revisions 0.78 3.2

Net Change 0.84 3.4

19.80 181.8

Cumulative production:

14.14 160.7

Discoveries 0.00 0.0

Revisions 0.47 3.2

Net Change 0.47 3.2

14.61 163.9

Remaining proved reserves:

4.82 17.7

Discoveries 0.06 0.2

Revisions 0.78 3.2

Production during 2005 -0.47 -3.2

Net Change 0.37 0.2

5.19 17.9

Oil Gas

(billion bbl) (trillion cu ft)

Previous estimates, as of 12/31/2004*

Estimate, as of 12/31/2005 (this report)

*Crawford and others, 2008

Previous estimates, as of 12/31/2004*

Estimate, as of 12/31/2005 (this report)

Previous estimates, as of 12/31/2004*

Estimate, as of 12/31/2005 (this report)
45

Table 6 presents all previous reserve estimates by year. Because of adjustments and corrections to production data 

submitted by Gulf of Mexico OCS operators, the difference between historical cumulative production for successive 

years does not always equal the annual production for the latter year. No comparisons will be made for unproved 

reserves. 

 

Table 6. Proved oil and gas reserves and cumulative production at end of year, 1975-2005, 

Gulf of Mexico, Outer Continental Shelf and Slope. 

 Oil Gas BOE Oil Gas BOE Oil Gas BOE

1975 255 6.61 59.9 17.27 3.82 27.2 8.66 2.79 32.7 8.61 

1976 306 6.86 65.5 18.51 4.12 30.8 9.60 2.74 34.7 8.91 

1977 334 7.18 69.2 19.49 4.47 35.0 10.70 2.71 34.2 8.80 

1978 385 7.52 76.2 21.08 4.76 39.0 11.70 2.76 37.2 9.38 

1979 * 417 7.71 82.2 22.34 4.83 44.2 12.69 2.88 38.0 9.64 

1980 435 8.04 88.9 23.86 4.99 48.7 13.66 3.05 40.2 10.20 

1981 461 8.17 93.4 24.79 5.27 53.6 14.81 2.90 39.8 9.98 

1982 484 8.56 98.1 26.02 5.58 58.3 15.95 2.98 39.8 10.06 

1983 521 9.31 106.2 28.21 5.90 62.5 17.02 3.41 43.7 11.19 

1984 551 9.91 111.6 29.77 6.24 67.1 18.18 3.67 44.5 11.59 

1985 575 10.63 116.7 31.40 6.58 71.1 19.23 4.05 45.6 12.16 

1986 645 10.81 121.0 32.34 6.93 75.2 20.31 3.88 45.8 12.03 

1987 704 10.76 122.1 32.49 7.26 79.7 21.44 3.50 42.4 11.04 

1988 + 678 10.95 126.7 33.49 7.56 84.3 22.56 3.39 42.4 10.93 

1989 739 10.87 129.1 33.84 7.84 88.9 23.66 3.03 40.2 10.18 

1990 782 10.64 129.9 33.75 8.11 93.8 24.80 2.53 36.1 8.95 

1991 819 10.74 130.5 33.96 8.41 98.5 25.94 2.33 32.0 8.02 

1992 835 11.08 132.7 34.69 8.71 103.2 27.07 2.37 29.5 7.62 

1993 849 11.15 136.8 35.49 9.01 107.7 28.17 2.14 29.1 7.32 

1994 876 11.86 141.9 37.11 9.34 112.6 29.38 2.52 29.3 7.73 

1995 899 12.01 144.9 37.79 9.68 117.4 30.57 2.33 27.5 7.22 

1996 920 12.79 151.9 39.82 10.05 122.5 31.85 2.74 29.4 7.97 

1997 957 13.67 158.4 41.86 10.46 127.6 33.17 3.21 30.8 8.69 

1998 984 14.27 162.7 43.22 10.91 132.7 34.52 3.36 30.0 8.70 

1999 1,003 14.38 161.3 43.08 11.40 137.7 35.90 2.98 23.6 7.18 

2000 1,050 14.93 167.3 44.70 11.93 142.7 37.32 3.00 24.6 7.38 

2001 1,086 16.51 172.0 47.11 12.48 147.7 38.77 4.03 24.3 8.35 

2002 1,112 18.75 176.8 50.21 13.05 152.3 40.15 5.71 24.6 10.09 

2003 1,141 18.48 178.2 50.19 13.61 156.7 41.49 4.87 21.5 8.70 

2004 1,172 18.96 178.4 50.70 14.14 160.7 42.73 4.82 17.7 7.97 

2005 1,196 19.80 181.8 52.15 14.61 163.9 43.77 5.19 17.9 8.38 

Oil expressed in billions of barrels; gas in trillions of cubic feet. "Oil" includes crude oil and condensate; 

"gas" includes associated and nonassociated gas. Remaining proved reserves estimated as of December 

31 each year.

 * Gas plant liquids dropped from system

Remaining 

proved 

reserves

 + Basis of reserves changed from demonstrated to SPE proved.

Year

Number of 

fields 

included

Proved 

reserves

Historical 

cumulative 

production
46

Conclusions

As of December 31, 2005, the 1,196 proved oil and gas fields in the federally regulated part of the Gulf of Mexico 

OCS contained proved reserves estimated to be 19.80 billion barrels of oil and 181.8 trillion cubic feet of gas. 

Cumulative production from the proved fields accounts for 14.61 billion barrels of oil and 163.9 trillion cubic feet of 

gas. Remaining proved reserves are estimated to be 5.19 billion barrels of oil and 17.9 trillion cubic feet of gas for the 

951 proved active fields. Remaining proved oil reserves have increased 8 percent and the remaining proved gas 

reserves have increased 1 percent from last year’s report. 

Unproved reserves in the federally regulated part of the Gulf of Mexico OCS are estimated to be 3.23 billion barrels of 

oil and 8.4 trillion cubic feet of gas. Included are unproved reserves of 2.96 billion barrels of oil and 4.2 trillion cubic 

feet of gas from 118 fields in water depths greater than 1,000 feet. Estimated unproved reserves for oil are 6.9 times 

annual oil production, and for gas are 2.6 times greater than annual gas production. 

Annual oil production is expected to ramp up as more fields recover from the effects of an active hurricane season, 

while gas production is expected to level off at rates below those seen in the 1990’s. The increase in remaining 

proved oil reserves is likely to continue as new deepwater discoveries become proved. 

In addition to the proved and unproved reserves discussed above, at a minimum there are 1.38 billion barrels of oil 

and 7.6 trillion cubic feet of gas that are not presented in the tables and figures of this report. This oil and gas occurs 

on leases that have not yet qualified (and therefore are not placed in a field) or they occur as known resources in 

proved fields, or as known resources in unproved fields. As further drilling and development occur, these additional 

hydrocarbon volumes will become reportable, and it is anticipated that future proved and unproved reserves will 

increase accordingly. 

Contributing Personnel

This report includes contributions from the following Gulf of Mexico Region, Office of Resource Evaluation, personnel. 

John S. Duhon 

Kellie K. Lemoine 

Lesley D. Nixon 

Chee W. Yu 
47

References

Attanasi, E.D., 1998, Economics and the National Assessment of United States Oil and Gas Resources, U.S. 

Geological Survey Circular 1145, United States Government Printing Office, Washington, D.C., Table A-4, p. 29. 

Bascle, B.J., L.D. Nixon, and K.M. Ross, 2001, Atlas of Gulf of Mexico Gas and Oil Sands as of January 1, 1999, 

U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, Office of Resource 

Evaluation, OCS Report MMS 2001-086, New Orleans, 342 p. Internet Web site: http://www.gomr/mms.gov/

homepg/gomatlas/atlas.html

Hasseltine, George, 2008, Indicated Hydrocarbon List, Central, Western, and Eastern Gulf of Mexico, U. S. 

Department of the Interior, Minerals Management Service, Gulf of Mexico Region. Internet Web site: http://www. 

gomr.mms.gov/homepg/offshore/gulfocs/hclist/hclist.html

Crawford, T.G., G.L. Burgess, S.M. Haley, C.J. Kinler, G.D. Klocek, M.T. Prendergast and N.K. Shepard, 2008, 

Estimated Oil and Gas Reserves, Gulf of Mexico Outer Continental Shelf, December 31, 2004, U. S. Department of 

the Interior, Minerals Management Service, Gulf of Mexico Region, OCS Report MMS 2008-034, New Orleans, 48 p. 

Internet Web site: http://www.gomr.mms.gov/homepg/offshore/fldresv/resvmenu.html

Nixon, L.D., C.M. Bohannon, M.P. Gravois, E.G. Kazanis, T.M. Montgomery, G.E. Richardson, 2008, Deepwater 

Gulf of Mexico 2008: America’s Offshore Energy Future, U.S. Department of the Interior, Minerals Management 

Service, Gulf of Mexico Region, OCS Report MMS 2008-013, New Orleans, 102 p. Internet Web site: 

http://www.gomr.mms.gov/PDFs/2008/2008-013.pdf

Karl, K.J., R.D. Baud, A.G. Boice, R. Bongiovanni, T.M. DeCort, R.P. Desselles, E.G. Kazanis, Gulf of Mexico Oil 

and Gas Production Forecast: 2007-2016, U.S. Department of the Interior, Minerals Management Service, Gulf of 

Mexico Region, OCS Report MMS 2007-020, New Orleans, 19 p. Internet Web site: http://www.gomr.mms.gov/

PDFs/2007/2007-020.pdf

Lore, G.L., 1994, An Exploration and Discovery Model; An Historic Perspective—Gulf of Mexico Outer Continental 

Shelf, In: K. Simakov and D. Thurston (eds.), Proceedings of the 1994 International Conference on Arctic Margins, 

Russian Academy of Sciences, Magadan, p. 306-313. 

Lore, G.L., D.A. Marin, E.C. Batchelder, W.C. Courtwright, R.P. Desselles, Jr., and R.J. Klazynski, 2001, 2000

Assessment of Conventionally Recoverable Hydrocarbon Resources of the Gulf of Mexico and Atlantic Outer 

Continental Shelf as of January 1, 1999, U.S. Department of the Interior, Minerals Management Service, Gulf of 

Mexico OCS Region, Office of Resource Evaluation, OCS Report MMS 2001-087, New Orleans, 652 p. Internet 

Web site: http://www.gomr.mms.gov/homepg/offshore/gulfocs/assessment/assessment.html

Lore, G.L. 2006, Assessment of Undiscovered Technically Recoverable Oil and Gas Resources of the Nation’s Outer 

Continental Shelf, 2006, U.S. Department of the Interior, Minerals Management Service, Resource Evaluation 

Division, 6 p. Internet Web site: http://www.mms.gov/revaldiv/PDFs/2006NationalAssessmentBrochure.pdf

Office of the Federal Register, National Archives and Records Administration, 1992, Code of Federal Regulations, 30 

CFR, Mineral Resources, U.S. Government Printing Office, Washington, D.C. 

Society of Petroleum Engineers (SPE), World Petroleum Congress (WPC), American Association of Petroleum 

Geologists (AAPG), and Society of Petroleum Evaluation Engineers (SPEE), 2007, Petroleum Resource 

Management System, 49p. Internet Web site: http://www.spe.org/spe-app/spe/industry/reserves/prms.htm

U.S. Department of Energy (DOE), 1989, Conversion Factors, Monthly Energy, December 1989, p. 132-133. 

U.S. Department of the Interior, U.S. Geological Survey and Minerals Management Service, 1989, Estimates of 

Undiscovered Conventional Oil and Gas Resources in the United States)–A Part of the Nation’s Energy Endowment, 

44 p. 

U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico Region, Gulf of Mexico OCS Deep 

Gas Update: 2001-2002, OCS Report MMS 2003-026, New Orleans, 8 p. Internet Web site: 

http://www.gomr.mms.gov/homepf/offshore/deepgas.html

U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico Region, OCS Operations Field 

Directory, 2007, New Orleans, 178 p. Internet Web site: http://www.gomr.mms.gov/homepg/offshore/fldresv/

mastlist.html
48

Notice

This report, Estimated Oil and Gas Reserves, Gulf of Mexico, December 31, 2005, has undergone numerous 

changes over the last few years. We are continually striving to provide meaningful information to the users of this 

document. Suggested changes, additions, or deletions to our data or statistical presentations are encouraged so we 

can publish the most useful report possible. Please contact the Reserves Section Chief at (504) 736-2918 at 

Minerals Management Service, 1201 Elmwood Park Boulevard, MS 5130, New Orleans, Louisiana 70123-2394, to 

communicate your ideas for consideration in our next report. 

For free publication and digital data, visit the Gulf of Mexico Internet web site. The report can be accessed as an 

Acrobat .pdf (portable document format) file, which allows you to view, print, navigate, and search the document with 

the free downloadable Acrobat Reader 9.0. Digital data used to create the tables and figures presented in the 

document are also accessible as either tab-delimited ASCII text files (.txt; viewable using NotePad or WordPad) or 

as Excel 97 spreadsheet files (.xls; using Microsoft's Excel spreadsheet viewer, a free file viewer for users without 

access to Excel). These files are made available in a zipped format, which can be unzipped with the downloadable 

WinZip program. Soon to be available (for a nominal fee) is a CD-ROM that will include this report, digital data, and 

field production plots. 

For information on purchasing copies of this publication or the CD-ROM contact: 

Minerals Management Service 

Gulf of Mexico OCS Region 

Attn: Public Information Unit (MS 5034) 

1201 Elmwood Park Boulevard 

New Orleans, Louisiana 70123-2394 

(504) 736-2519 or 1-800-200-GULF 

http://www.gomr.mms.gov

David A. Marin 

Regional Supervisor 

Resource Evaluation 

 

The Department of the Interior Mission 

As the Nation's principal conservation agency, the Department of the Interior has 

responsibility for most of our nationally owned public lands and natural resources. This 

includes fostering sound use of our land and water resources; protecting our fish, wildlife, and 

biological diversity; preserving the environmental and cultural values of our national parks and 

historical places; and providing for the enjoyment of life through outdoor recreation. The 

Department assesses our energy and mineral resources and works to ensure that their 

development is in the best interests of all our people by encouraging stewardship and citizen 

participation in their care. The Department also has a major responsibility for American Indian 

reservation communities and for people who live in island territories under U.S. administration. 

The Minerals Management Service Mission 

As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) 

primary responsibilities are to manage the mineral resources located on the Nation's Outer 

Continental Shelf (OCS), collect revenue from the Federal OCS and onshore Federal and 

Indian lands, and distribute those revenues. 

Moreover, in working to meet its responsibilities, the Offshore Minerals Management 

Program administers the OCS competitive leasing program and oversees the safe and 

environmentally sound exploration and production of our Nation's offshore natural gas, oil and 

other mineral resources. The MMS Minerals Revenue Management meets its 

responsibilities by ensuring the efficient, timely and accurate collection and disbursement of 

revenue from mineral leasing and production due to Indian tribes and allottees, States and the 

U.S. Treasury. 

The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially 

affected parties and (2) carrying out its programs with an emphasis on working to enhance the 

quality of life for all Americans by lending MMS assistance and expertise to economic 

development and environmental protection. 

 

MMS 

Securing Ocean Energy & 

Economic Value for America