U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

ASSESSMENT OF DEEP CONVENTIONAL AND CONTINUOUS-TYPE

(UNCONVENTIONAL) NATURAL GAS PLAYS IN THE UNITED STATES

by

Thaddeus S. Dyman^, James W. Schmoker^, and David H. Root2

Open-File Report 96-529

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

!U.S. Geological Survey, P.O. Box 25046, MS 939, Denver, CO 80225

2 U.S. Geological Survey, National Center, MS 956 Reston, VA 20192

Assessment of Deep Conventional and Continuous-type (unconventional) Natural Gas Plays inthe United States

by

Thaddeus S. Dyman, James W. Schmoker, and David H. Root

INTRODUCTIONBecause of depressed worldwide oil prices and the highly mature state of drilling and

production in many United States basins, domestic drilling activity has declined and exploration companies are looking overseas for new prospects. Concurrently, domestic oil production is declining and United States reliance on imported oil is increasing. Even if prices were to increase drastically, it would take several years for domestic exploration to reach previous levels of intensity. When the issue of economics is set aside, many domestic drilling frontiers deserve review. One such frontier is natural gas in deep sedimentary basins (Fig. 1).

The United States is rapidly exhausting its oil reserves, whereas estimates of resources of natural gas remain high. According to the National Petroleum Council (1992), the United States contains nearly 1,300 trillion cubic feet (TCP) of recoverable natural gas resources. In 1995, the U.S. Geological Survey estimated that 939 TCP of technically recoverable natural gas remained to be discovered or was part of reserve appreciation from known fields in the onshore areas and State waters of the United States (U.S. Geological Survey Oil and Gas Resource Assessment Team, 1995).

According to Petroleum Information Corporation's Well History Control System (WHCS) (Petroleum Information Corporation, 1991), more than 16,000 wells have been drilled deeper than 15,000 feet in the United States (Dyman and others, in press). These deep wells are widely distributed and are drilled into rocks of various ages and lithologies, but they represent less than one percent of the more than three million wells drilled in the United States.

Almost one fifth of the total undiscovered natural gas resources of the onshore and offshore United States are estimated to occur below 15,000 feet according to the Potential Gas Committee (1995). For example, one of the most significant exploration plays in the United States is the deep Norphlet Formation (Upper Jurassic) play of the eastern Gulf Coast Basin region (Fig. 1; Appendix A). Geologic and geochemical studies by Rice and others (1992) indicated significant potential for Norphlet and perhaps Upper Jurassic Smackover Formation natural gas reservoirs in the eastern Gulf region. In other deep basins, only a few deep wells have been drilled, and the natural gas potential of deep horizons remains poorly known.

Known deep natural gas reservoirs are distributed throughout many United States basins and occur in widely different geologic environments. However, when the Nation is taken as a whole, deep natural gas reservoirs account for only a small portion of the total natural gas production. According to Dwights Energy Data (1986), 1,998 producing reservoirs existed below 15,000 feet in the United States at the end of 1985. Of the total cumulative natural gas production in the United States (698 TCP; Mast and others, 1989), deep reservoirs accounted for seven percent (50 TCP) of which so-called significant reservoirs accounted for nearly half (22.4 TCP; Table 1; NRG Associates, 1990; Dyman and others, in press). Significant reservoirs are defined as those reservoirs with known recoverable size of at least six billion cubic feet (BCF) of gas. Two-hundred fifty-six known significant reservoirs, as identified by NRG Associates (1990), produce from depths greater than 15,000 feet, and 377 significant reservoirs produce from depths greater than 14,000 ft out of a total of more than 15,000 significant reservoirs in the United States (Table 1).

In this report, deep reservoirs are defined as those occurring at or below 15,000 feet; however, a single producing interval may extend both above and below 15,000 feet. For this reason, NRG data in Table 1 were summarized for all producing reservoirs below 14,000 feet in order to capture all reservoirs potentially occurring at or below the 15,000-ft level. Nearly three quarters of these reservoirs produce natural gas. These reservoirs occur in the Gulf Coast,

Permian, Anadarko, Williston, San Joaquin, Ventura, Cook Inlet, and Rocky Mountain basins (Figs. 1 and 2; Table 1).

One-hundred sixty two deep conventional and 11 continuous-type unconventional plays were defined for the U.S. Geological Survey 1995 National Petroleum Assessment (Gautier and others, 1995). One-hundred one of the conventional plays and six of the unconventional plays demonstrate potential for undiscovered technically-recoverable non-associated natural gas (Table 2; Appendix A).

Deep natural gas resources are described and assessed here for three primary reasons: (1) Natural gas may form in the deep central portions of basins and migrate into shallower regions where it is trapped. An understanding of deep basin processes may aid in understanding the occurrence of natural gas in shallow basin environments as well as deep ones. (2) The deeper parts of many sedimentary basins have not been adequately drilled, and opportunities for undiscovered accumulations remain good. (3) Economic conditions strongly affect the development of deep reservoirs, and an economic upturn or improved technology could produce conditions appropriate for increased exploration. Therefore, it is very important to maintain a data base of information on deep natural gas resources and reservoirs.

This report describes both conventionally-trapped and continuous-type (unconventional) plays and resources from the 1995 U. S. Geological Survey National Petroleum Assessment (U.S. Geological Survey Oil and Gas Resource Assessment Team, 1995). It contains (1) a description of deep conventional and continuous-type natural gas plays based on geologic data supplied by province geologists; (2) estimates of undiscovered technically-recoverable gas from these plays; and (3) a comparison of other recent deep natural gas assessments with the 1995 U.S. Geological Survey assessment.

Field and reservoir data were taken primarily from the Significant Field File of NRG Associates Inc. (NRG Associates, 1990). The NRG data base contains identification information, and geologic, production, and engineering data for more than 15,000 oil and gas reservoirs in the United States.

Deep plays were compiled from play descriptions supplied by province geologists and are identified in Appendix A. Many of these deep plays have a potential for both undiscovered oil and gas accumulations and are identified accordingly. For detailed discussions of plays and maps illustrating play outlines of all plays discussed in this report, refer to regional or province reports included in the 1995 U.S. Geological Survey National Petroleum Assessment CD-ROM (Gautier and others, 1995).

METHODOLOGY Conventional Plays

The 1995 U.S. Geological Survey National Petroleum Assessment was based on the play concept, where a play is defined as a set of geologically similar discovered and undiscovered accumulations of oil and/or gas (Gautier and Dolton, 1995). A play is not a single drillable prospect but includes several prospects with similar geologic characteristics. It may have an exploration potential for conventional or unconventional accumulations and may be considered either hypothetical (no known discovery history of fields greater than 1 MMBO or 6 BCF) or confirmed (known discovered accumulations). The number of plays in equivalently-sized provinces may vary somewhat based on the manner in which each province geologist interpreted available data and on individual preferences for combining or subdividing geologic attributes. For example, 23 deep conventional plays were identified in the Western Gulf Basin while only five such plays were identified in the Permian Basin. The deep structural gas play of the Permian Basin includes several different reservoirs each of which could be defined as a separate play.

Confirmed plays were analyzed using field-size distributions, numbers of known accumulations, depths to production, and other geologic and production factors. Hypothetical plays were analyzed using geologic analogs or simulation models based on geological, geophysical, and geochemical data. Hypothetical plays were risked if some uncertainty existed as to the occurrence of at least one 1-MMBO or 6-BCFG accumulation. Play risk was expressed as a probability between 0.0 and 1.0 (see Appendix A) based on the product of estimates for

three play attributes: (1) charge, which includes the presence of source rocks, adequate time- temperature history, and migration; (2) presence of reservoir rocks; and (3) trap, including seal integrity and hydrocarbon retention (Gautier and Dolton, 1995).

In the assessment of conventional plays, a Truncated Shifted Pareto (TSP) distribution was used to model the size-frequency distribution of the population of oil and gas accumulations (Houghton and others, 1993). TSP data were combined with available geologic and production data in order to develop hypotheses about undiscovered conventional accumulations within a play and to estimate the sizes and numbers of accumulations remaining to be discovered for each play. Using play probability and other data, the numbers and sizes of undiscovered accumulations were subjected to Monte Carlo simulation to calculate a range of resources. Play-level assessments were subjected to review and compiled into province, regional, and National totals (Gautier and Dolton, 1995).

Small undiscovered accumulations (< 1 MMBO or 6 BGF) in conventional plays were treated separately for 1995 assessment based on extrapolations of numbers of field size classes greater than 1 MMBO or 6 BCF (Root and Attanasi, 1993). This estimate was made at the province level only and was not subdivided by depth interval. Data for small fields are therefore not included in this deep gas assessment.

Because of uncertainties in estimating undiscovered accumulations of oil and gas, estimates were presented as a range of values associated with different probabilities of occurrence for each play. A pessimistic case has at least a 95-percent chance of occurrence, an optimistic case has at least a 5-percent chance of occurrence, and a mean case represents the arithmetical average of all possible outcomes weighted by their probability. Appendix A includes only mean estimates for each play. The full range of estimates can be found in Gautier and others (1995). Resources attributed to reserve additions from known accumulations are not available at the play level but are substantial. Three-hundred twenty-two TCP of gas is identified in 1995 assessment as attributed to reserve appreciation from known fields for all reservoirs at all depths. Reserve additions to known deep fields are therefore not included in this deep gas assessment.

Undiscovered natural gas resources were subdivided into depth slices by using the average of two density functions. One density function is uniform between the minimum and median depth of the play, and between the median and maximum depth of the play. The other density function is linear, increasing from the minimum to the median depth and linear, decreasing from the median to the maximum depth with a discontinuity at the median. The result of this computation was a fraction of the total resource in 5,000-ft-thick depth slices. The greater-than 15,000 ft depth interval was represented as a single fraction.

Continuous-type PlaysContinuous-type plays were treated as a separate category in the 1995 National Petroleum

Assessment and were assessed using a specialized methodology developed by the U.S. Geological Survey (Schmoker, 1995). These continuous-type plays are geologically diverse and fall into the following categories: coal-bed gas, some biogenic gas occurrences, fractured gas shales, and basin-centered natural gas accumulations. Only continuous-type basin-centered gas plays comprise significant future undiscovered resources in deep sedimentary basins.

Continuous-type accumulations identified in this report are not significantly affected by oil/water or gas/water contacts (Schmoker, 1995); therefore, the methodology used for assessing discrete accumulations of conventional plays is not appropriate here. Continuous-type accumulations are essentially large, potentially productive areas that cannot be defined in terms of discrete units with down-dip hydrocarbon-water contacts. The definition of continuous-type accumulations is based on geology rather than on government regulations defining tight gas.

The assessment of continuous-type plays is based on the concept that an accumulation can be regarded as a collection of hydrocarbon-bearing cells. In the play, cells represent spatial subdivisions defined by the drainage area of wells. Cells may be productive, nonproductive, or untested. Geologic risk, expressed as play probability, was assigned to each play. The number of untested cells in a play, and the fraction of untested cells expected to become productive (success ratio) were estimated, and a probability distribution was defined for estimated ultimate

recovery (EUR) for those expected to become productive cells. The combination of play probability, success ratio, number of untested cells, and EUR probability distribution yielded potential undiscovered resources for each play. Resources were assigned to 5,000-ft. depth slices in the same way as conventional plays.

DEEP UNDISCOVERED NATURAL GAS PLAYS AND RESOURCESAppendix A contains information on deep conventional plays including province and play

name, play classification as hypothetical or confirmed, depth range, fractional distribution of gas, and undiscovered conventional resources. Table 2 identifies play name, minimum, median, and maximum depth, and undiscovered resources for six continuous-type plays assessed in the U.S. Geological Survey 1995 National Petroleum Assessment. Five additional plays are identified but not assessed due to a lack of geologic information about each of them. Refer to Figure 3 for locations of regions and provinces discussed in the following sections.

The U.S. Geological Survey estimated 55.3 TCF of undiscovered technically-recoverable non-associated gas and associated gas from oil fields for 101 deep conventional plays in the lower-48 states and Alaska onshore and State waters. In addition to these gas-bearing plays, 61 conventional plays are identified in Appendix A but have do not have undiscovered gas resources attributed to them. These plays include those that (1) may contain only negligible associated gas because they are oil plays, (2) were severely risked and no gas was assessed for them, or (3) have maximum depths of 15,000 ft and have no gas resource assigned below that depth. About 83 percent of the deep undiscovered conventional resource, or 45.3 TCF of gas, was assessed from the Gulf Coast and Alaska Regions together (Fig. 4; Appendix A). Approximately half of the estimated undiscovered conventional gas (27.4 TCF) is located in the Gulf Coast region in the Western Gulf Basin and Louisiana-Mississippi Salt Basins petroleum provinces. This deep conventional resource does not include deep resources from small fields (<6 BCF of gas) or reserve appreciation from known fields.

An additional 58.4 TCF of technically-recoverable gas was assessed for six continuous-type plays in the Pacific, Colorado Plateau and Basin and Range, and Rocky Mountain and Northern Great Plains Regions (Fig. 4; Table 2). Four of these plays are in Cretaceous and Tertiary low- permeability sandstone reservoirs in the Greater Green River Basin of Wyoming and are estimated to contain 50 percent of the entire undiscovered deep gas resource estimated for the United States. The disparity in numbers and resources of conventional (101 plays 55.3 TCF) and unconventional continuous-type (six plays-58.4 TCF) plays may be due in part to a lack of data dealing with the distribution of poorly understood "basin-centered" gas accumulations. The five "unassessed" continuous-type plays in Table 5 are part of this "poorly understood" category. Not included in Table 5 are other plays that may exist but were not even defined because of a lack of geologic information. For example, deep plays may exist in basins of interior Alaska, in basins of coastal California, and in basins in the Rocky Mountain Region such as the Crazy Mountains Basin, Raton Basin, and Albuquerque Basin.

The number of deep conventional plays identified decreases with increasing depth. Of the 101 conventional gas-bearing plays, 73 plays have maximum depths ranging from 15,000 to 20,000 feet, whereas 20 have maximum depths ranging from 20,001 to 25,000 feet, and 5 have maximum depths ranging from 25,001 to 30,000+ feet. Three plays exceed 30,000 feet in depth. Seventy gas-bearing plays are confirmed (those having known production from significant reservoirs), whereas, 31 are hypothetical. Nearly 40 percent of the confirmed plays are in the Gulf Coast Region, and about 60 percent of the plays are in the Gulf Coast and Rocky Mountain Regions together. Eighty-five of 101 gas-bearing plays have a fractional distribution for non-associated gas of 0.5 or greater. Thirty-six of these plays are in the Gulf Coast Region. Fifty-nine confirmed plays have more than half of their estimated resources in the form of non- associated gas (a fractional distribution for non-associated gas accumulations of 0.5 or greater). Thirty confirmed conventional deep plays have less than half of their estimated resources in the form of non-associated gas (a fractional distribution for non-associated gas of less than 0.5). Only in the Pacific Region does the number of plays having no chance for undiscovered non-

associated gas accumulations exceed the number of plays in which half or more of their resources are non-associated gas.

REGION 1--ALASKAThe petroleum geology of Alaska is complex in part because of the accretion of exotic

terranes to the ancestral North American cratonic margin (Bird, 1995). Numerous sedimentary basins evolved before, during, and after this accretion process. The Central Alaska Province contains nonmarine rocks in a series of poorly understood basins. The Northern Alaska Province includes large, deep composite basins such as the North Slope Basin, while the Southern Alaska Province includes forearc basins of the Pacific margin, primarily containing thick sequences of Tertiary marine and nonmarine rocks. Alaska provinces are frontier areas with respect to deep drilling.

Deep Conventional PlaysThe three Alaska provinces include 21 deep conventional plays (Fig. 3; Appendix A).

Seven of these plays, six of which are located in northern Alaska, were assessed as containing 17.7 TCP of undiscovered technically-recoverable non-associated gas. Deep undiscovered resources were not estimated to exist in the Central Alaska Province. Northern Alaska has the largest number of plays of the three provinces with 10. Only eight of the 21 plays are confirmed, indicating that Alaska petroleum provinces are relatively undrilled. For Alaska as a whole, the average maximum depth of deep conventional plays exceeds 21,000 feet. The deepest plays in the region are the hypothetical Western Thrust Belt Play (110), and Lisburne, Lisburne Unconformity and Endicott Plays (106, 107, and 108) in northern Alaska, which reach maximum depths of 35,000 and 30,000 feet respectively. Deep conventional plays in Alaska are estimated to contain 17.7 TCP of undiscovered technically-recoverable non-associated gas and 271.4 BCF of associated gas from oil fields (Appendix A; Fig. 4).

Deep Continuous-type PlaysDeep continuous-type plays were not identified or assessed in the Alaska Region.

REGION 2--PACIFIC COASTThe Pacific Coast Region includes Washington, all but the southeastern quarter of Oregon,

and that part of California west of the Sierra Nevada Range (Bird and others, 1995). The geology of the region is complex because of arc-related volcanism and plutonism, subduction, crustal accretion, eruption of flood basalts, and the development of numerous small deep basins. The region is subdivided into 8 geologically distinct provinces containing deep resource potential: Western Washington and Oregon, Eastern Washington and Oregon, Northern Coastal, Sonoma- Livermore Basin, Sacramento Basin, San Joaquin Basin, Central Coastal, and Ventura Basins. Deep plays were not identified for the Los Angeles Basin in the 1995 National Petroleum Assessment. Regions 1 and 2 together have known deep ultimate recoverable gas of 0.3 TCP from deep significant reservoirs found in the NRG Associates Data File (Fig. 2; Table 1).

Deep Conventional PlaysRegion 2 contains 20 deep plays (Fig. 3; Appendix A). Washington and Oregon provinces

are generally gas prone, whereas most California provinces are oil prone. The Sacramento Basin is gas prone and is estimated to contain 94.7 BCF of undiscovered technically-recoverable non- associated gas from two deep plays. Although oil prone, the Ventura Basin is estimated to contain 97.8 BCF of undiscovered technically-recoverable non-associated gas from two Paleogene plays (1301 and 1311). The San Joaquin Basin Province contains the largest number of deep plays with six, although only undiscovered oil was assessed for them.

Eight of 20 plays are hypothetical indicating that the region is relatively immature with respect to deep natural gas exploration. For the region as a whole, the average maximum depth of deep plays is about 18,000 feet. The deepest play is the hypothetical Deep Overpressured Fractured Rocks of West Side Fold and Overthrust Belt Play (1011) of the San Joaquin Basin

7

which reaches a maximum depth of 25,000 feet. Other California basins such as the Los Angeles Basin contain deep sedimentary rocks, but no deep conventional plays were assessed for them. The Los Angeles Basin contains one deep oil play but it was not assessed because it is not expected to produce oil fields larger than 1 MMBO. In the Western Oregon and Washington Province, the Puget Lowland Deep Gas (403) and Torino Fuca Basin Gas (404) Plays contain 15.2 BCF of undiscovered non-associated technically-recoverable gas. Deep conventional plays in the Pacific Region contain 208.3 BCF of undiscovered technically-recoverable non-associated gas and 341.3 BCF of associated gas from oil fields (Appendix A; Fig. 4).

Deep Continuous-type PlaysOnly one deep continuous-type play was assessed in the Pacific Region: the Columbia

Basin-Basin-Centered Gas Play (503) in the Eastern Oregon-Washington Province (Table 2). This play underlies Tertiary Columbia River basalts in central and eastern Washington. The play is sparsely drilled. The top of an overpressured interval ranges in depth from more than 8,000 to more than 12,000 feet and may be as much as 6,400 feet thick (B.E. Law, in Schmoker and Oscarson, 1995). Play 503 contains 2.6 TCP of deep undiscovered technically-recoverable gas (Table 2).

Two additional continuous-type plays, the Willamette-Puget Sound Basin-Centered Gas Play (412) of the Western Oregon-Washington Province, and the Deep, Overpressured Fractured Rocks of the Central Syncline Play (1408) of the Los Angeles Basin were identified in Table 2, but not assessed, because of a lack of available geologic information.

REGION 3--COLORADO PLATEAU AND BASIN AND RANGEThe Colorado Plateau and Basin and Range Region includes nine petroleum provinces in

Nevada, Idaho, Arizona, eastern California, southeastern Oregon, western and southern Utah, southwestern Colorado, and western New Mexico (Fig. 3; Peterson and Grow, 1995). The geology of the region is typified by Late Precambrian to Early Paleozoic passive continental- margin sedimentation dominated by more than 30,000 feet of shallow-water carbonate and clastic rocks. This continental margin was subjected to repeated compression and plutonism during the Late Paleozoic and Late Mesozoic culminating in Sevier-style tectonism during the Late Cretaceous. The Colorado Plateau part of the region has remained tectonically stable since the Paleozoic, but the Basin and Range was tectonically partitioned into numerous non-marine basins during the Tertiary. The entire region has a fair potential for undiscovered deep natural gas accumulations. Region 3 has no deep significant reservoirs in the NRG Associates Data File (Fig. 2; Table 1).

Deep Conventional PlaysThe Colorado Plateau Basin and Range Region contains 22 deep plays. Nine of 22 plays

have potential for undiscovered technically-recoverable non-associated gas at or below 15,000 feet (Appendix A). In 11 plays, the gas fraction is 0.5 or greater. Plays are relatively equally distributed among the provinces. Only two of 22 plays, both in the Paradox Basin, are confirmed indicating that the deeper parts of most of the region are relatively undrilled. For the region as a whole, the average maximum depth of deep conventional plays is about 19,000 feet. The deepest plays, each reaching maximum depths of 25,000 feet, are in the Snake River Downwarp Province (Older Tertiary Play-1704), Western Great Basin Province (Neogene Source Rocks, Northwestern Nevada and Eastern California Play-1805, and Permian-Triassic Source Rocks Northwestern Nevada and East Central and Eastern Oregon Play 1803), and Southern Arizona Southwestern New Mexico Province (Alamo Hueco Basin Play 2501). Deep conventional plays in the Colorado Plateau Basin and Range Region contain 127.0 BCF of undiscovered technically-recoverable non-associated gas and 2.7 BCF of associated gas from oil fields (Appendix A; Fig. 4).

Deep Continuous-type Plays

8

Only one deep continuous-type gas play, the Deep Synclinal Uinta Mesaverde Play (2020) in the Uinta-Piceance Basin, was assessed in the Colorado Plateau-Basin and Range Region. This play is defined on the occurrence of gas-charged, low-permeability Late Cretaceous sandstones of the Mesaverde Group. The play is entirely below 15,000 feet and underlies conventional plays in overlying Tertiary rocks. The play contains an estimated 570 BCF of deep undiscovered technically-recoverable gas (Fig. 4).

REGION 4--ROCKY MOUNTAINS AND NORTHERN GREAT PLAINSThe Rocky Mountains and Northern Great Plains Region contains eight provinces with deep

gas plays (Fig. 3). Region 4 was part of the western United States cratonic margin during much of the Paleozoic. During Mesozoic and Tertiary time, Laramide- and Sevier-style tectonism disrupted the cratonic margin. Laramide structural basins may be very deep (Hanna Basin of the Southwestern Wyoming Province extends to more than 40,000 feet) and are gas prone (Spencer, 1995). Basins in the Rocky Mountains and Northern Great Plains Region have a known recoverable resource of 2.2 TCF of gas (Fig. 2; Table 1).

Deep Conventional PlaysThe Rocky Mountains and Northern Great Plains Region contains 29 deep plays in eight

provinces (Appendix A). Eighteen are predominantly deep gas plays (gas fraction equals or greater than 0.5), and only four of 18 plays have no non-associated gas potential (gas fraction equals 0.0). Two of these are in the Powder River Basin Province. Deep plays are relatively equally distributed throughout the region, but the Wyoming Thrust Belt Province and Southwestern Wyoming Province each contain the most, with six plays each. Nineteen of 29 deep plays are confirmed indicating that the region is relatively mature with respect to deep drilling. The average maximum depth of all deep plays within the region is about 18,900 feet. The deepest plays (Basin Margin Anticline and Subthrust Plays of Southwestern Wyoming Province; plays 3705, 3706) extend to 30,000 feet. Other Rocky Mountain basins containing deep sedimentary rocks such as the Raton Basin are not included here because deep conventional plays were not defined for them in the U.S. Geological Survey 1995 National Petroleum Assessment. Deep conventional plays in the Rocky Mountains and Northern Great Plains Region are estimated to contain 1.9 TCF of undiscovered technically-recoverable non-associated gas and 86.9 BCF of associated gas. Nearly half of this resource is in one play, the Moxa Arch Extension Play (3601) of the Wyoming Thrust Belt Province (Appendix A; Fig. 4).

Deep Continuous-type PlaysFour deep continuous-type plays were assessed for the Rocky Mountain Region (Table 2).

All four plays are in the Greater Green River Basin and occur in Cretaceous or Tertiary rocks as low-permeability basin-centered gas accumulations. Together they contain 55.2 TCF of undiscovered technically-recoverable gas, nearly one-half of the entire deep undiscovered technically-recoverable gas resource of the United States (Fig. 4). More than 90 percent of this resource (50.8 TCF) was estimated for the Cloverly-Frontier (3740) and Mesaverde (3741) Plays alone.

Two additional continuous-type plays, the Big Horn Basin Basin-Centered Gas Play (3404), and the Wind River Basin Basin-Centered Gas Play (3505) were identified in Table 2, but not assessed, because of a lack of available geologic information.

REGION 5--WEST TEXAS AND EASTERN NEW MEXICOProvinces within Region 5 have produced hydrocarbons for many years and include plays

with deep undiscovered natural gas accumulations (Fig. 3). During the Early Paleozoic, a thick shallow-water carbonate sequence was deposited in the region. Early Pennsylvanian deformation attributed to the Ouachita Orogeny trapped oil and gas in complex structural and stratigraphic traps. The Late Pennsylvanian through Permian sequence is composed of mixed clastic and carbonate rocks primarily in stratigraphic and combination traps. The region is geographically dominated by the Permian Basin (Ball and others, 1995). Forty-five percent of

the known ultimate recoverable deep natural gas resource identified for significant reservoirs (15.1 TCP) in the United States occurs in the Permian Basin (Fig. 2; Table 1).

Deep Conventional PlaysRegion 5 contains six deep plays in two petroleum provinces, all but one of which contain

conventional undiscovered technically-recoverable non-associated gas resources (Appendix A). All six plays contain non-associated gas potential, but the Pre-Pennsylvanian Delaware-Val Verde Basins Play (4401) and the lower Pennsylvanian (Bend) Sandstone Play (4404) have fractional distributions favoring gas accumulations. The Pre-Pennsylvanian Delaware Val Verde Basins Play (4401) contains the most deep significant reservoirs and the largest conventional non-associated gas potential. All six plays are confirmed and together range from 15,500 to 24,000 feet in maximum depth. These deep plays are primarily structural plays and include many different stratigraphic units, whereas the many shallower plays in the region are stratigraphic, and generally are defined on the basis of known stratigraphic units. These deep conventional plays are estimated to account for 4.7 TCP of undiscovered technically-recoverable non-associated gas and 6.3 BCF of associated gas from oil fields (Appendix A; Fig. 4).

Deep Continuous-type PlaysDeep continuous-type plays were not identified or assessed for the West Texas Eastern

New Mexico Region.

REGION 6--GULF COASTThe Gulf Coast Region includes the States and State waters that border the Gulf of Mexico

and extends northward to folded Paleozoic rocks of the inland fold belts (Schenk, 1995). The region represents the southern passive continental margin of North America and includes the Western Gulf Basin, East Texas Basin, Louisiana-Mississippi Salt Basins, and Florida Peninsula Provinces (Fig. 3). Since a Triassic rifting event, the region has experienced extensive sedimentation, progradation, and subsidence. The region is geologically complex because of rapid facies changes due to marine transgressions and regressions, and gravity and salt tectonism. Mesozoic strata are dominated by mixed carbonate and clastic sequences, while Cenozoic strata are dominated by clastic sequences. The Gulf Coast Region has been extensively drilled and is the foremost petroleum-producing region of the United States. Thirty-nine percent of the known ultimate recoverable natural gas resources (12.8 TCP; Table 1; Fig. 2) in deep significant reservoirs occurs in the Gulf Coast Region.

Deep Conventional PlaysThe distribution of deep plays in the Gulf Coast Region is very similar to the distribution of

known deep production. Nearly all of the plays have significant reservoirs; only six of 44 plays are hypothetical, indicating that the region is mature with respect to deep drilling (Appendix A). The Gulf Coast Region exceeds all other regions in numbers of deep plays, in part because of the extensive area of sediments deeper than 15,000 feet. Thirty-six plays are predominantly gas plays, and only five plays contain no potential for non-associated gas. These five oil plays are generally updip equivalents of deeper natural gas plays. The Western Gulf Province contains the most plays, and the Florida Peninsula Province contains the least. The average maximum depth of all deep plays in the region is nearly 20,000 feet. The two deepest plays, Norphlet Mobile Bay Deep Gas (4903) and Norphlet Southeast Margin Jackson Dome Flank Deep Gas (4907), extend to 24,000 feet.

The 44 plays in the Gulf Coast Region can be grouped on the basis of the stratigraphic or structural character of each play. For example, the four deep Smackover plays in the Louisiana- Mississippi Salt Basins Province are defined by their structural origin (such as Jackson Dome). Deep conventional plays in the Gulf Coast Region are estimated to account for 27.4 TCF of undiscovered technically-recoverable non-associated gas and 56.3 BCF of associated gas from oil fields (Appendix A; Fig. 4).

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Deep Continuous-type PlaysDeep continuous-type plays were not identified or assessed in the Gulf Coast Region.

REGION 7--MIDCONTINENTThe Midcontinent Region includes all or parts of Oklahoma, Kansas, Nebraska, Texas,

Arkansas, Missouri, Iowa, Minnesota, Wisconsin, and Colorado (Fig. 3; Charpentier, 1995). Geologically, the region represents the Paleozoic continental craton. The deepest basins, the Anadarko and Arkoma, are in the southern part of the region and formed as Early Paleozoic aulacogens. They were later altered tectonically by collisional events along the eastern and southern margin of the United States. In the northern and central parts of the region, Precambrian rifting led to the development of the Midcontinent rift. The region (excluding the Midcontinent rift) has been extensively drilled, but both confirmed and hypothetical deep natural gas plays still possess the potential for undiscovered accumulations.

All of the deep significant production from the NRG Associates Field File in the Midcontinent Region is found in the Anadarko Basin. The Anadarko Basin contains a known ultimate recoverable resource of 2.8 TCP from these deep reservoirs (Table 1; Fig. 2).

Deep Conventional PlaysThe Midcontinent Region includes eight deep plays in the Superior, Anadarko Basin,

Southern Oklahoma, and Arkoma Basin Provinces (Appendix A). All eight plays are classified as predominantly non-associated gas, and six of the eight plays are exclusively gas. The Anadarko and Arkoma Basins Provinces contain most of the plays with three each. Six of the eight plays are confirmed, and the average maximum depth of all deep plays in the region is about 24,000 feet. The Deep Structural Gas Play (5801) in the Anadarko Basin and the Deep Gas Play (6101) in Southern Oklahoma extend to 40,000 feet, and the two deepest wells drilled in the United States, the No. 1 Bertha Rogers and No. 1 Ernest Baden wells in the southern Anadarko Basin, are included in play 5801. Deep conventional plays in the Midcontinent Region are estimated to contain 2.3 TCP of undiscovered technically-recoverable non-associated gas (Appendix A; Fig. 4). The Deep Structural (5801) and Deep Stratigraphic Gas Plays (5812) of the Anadarko Basin contain most of the conventional undiscovered technically-recoverable non- associated gas (2.1 of 2.3 TCP).

Deep Continuous-type PlaysDeep continuous-type plays were not assessed in the Midcontinent Region. One additional

continuous-type play, the Woodford/Chattanooga/Arkansas Novaculite of Midcontinent (5811) was identified in Table 2, but not assessed because of a lack of available geologic information.

REGION 8--EASTERNRegion 8 includes most of the eastern United States in the following provinces: Illinois

Basin, Michigan Basin, Black Warrior Basin, Cincinnati Arch, Appalachian Basin, Blue Ridge Thrust Belt, Piedmont, Atlantic Coastal Plain, Adirondack Uplift, and New England (Fig. 3; Ryder, 1995). The Illinois and Michigan Basins are cratonic basins filled with Paleozoic sedimentary rocks and are underlain by Precambrian rift systems. The Appalachian and Black Warrior Basins are foreland basins recording complex histories of continental rifting, passive margin subsidence, continental collision, and basin subsidence. Up to 40,000 feet of sedimentary rocks are preserved in the eastern Pennsylvania part of the Appalachian Basin. The region has been extensively drilled for petroleum, but deep natural gas plays still possess the potential for undiscovered accumulations. No deep significant fields or reservoirs were identified in the NRG Associates Data File for the Eastern Region.

Deep Conventional PlaysRegion 8 includes 12 deep plays in five provinces: Michigan, Illinois, Black Warrior, and

Appalachian Basins, and Blue Ridge Thrust Belt Province (Appendix A). All 12 plays are predominantly non-associated gas plays, and eight of the 12 plays are entirely gas. The

11

Appalachian Basin Province contains the most plays with five. The Michigan and Illinois Basins and Blue Ridge Thrust Belt Provinces each contain one play. Six of the 12 plays are confirmed indicating that the region is moderately explored with respect to deep drilling. The Precambrian Rift Play (6315) of the Michigan Basin is the deepest play in the region and extends to 30,000 feet. Deep conventional plays in the Eastern Region account for 293.8 BCF of undiscovered technically-recoverable non-associated gas (Appendix A; Fig. 4). About 44 percent of this resource, or 129 BCF, was assigned to the Appalachian Basin.

Deep Continuous-type PlaysDeep continuous-type plays were not identified or assessed in the Eastern Region.

COMPARISON WITH OTHER RECENT NATIONAL ASSESSMENTSThe U.S. Geological Survey estimates that about 113.7 TCP of technically-recoverable

undiscovered gas remains to be discovered from the deeper portions (depths of 15,000 ft and greater) of deep sedimentary basins in the United States. About one-half of this estimated resource (58.4 TCF; Table 3) is attributed to six continuous-type unconventional plays in the Greater Green River Basin of Wyoming, the Columbia Plateau of Washington, and the Uinta Piceance Basin of Utah. About one-half of the remaining resource (27.4 TCF) occurs in conventional plays of the Gulf Coast Basin, and an additional one-third (17.9 TCF) in Alaska. Only 14 of 101 deep gas-bearing conventional plays are estimated to each contain more than 1 TCF of technically-recoverable undiscovered gas (Appendix A).

Table 3 lists undiscovered natural gas resources by region for four recent National petroleum assessments for which data are available at the regional level (refer also to Fig. 5). Totals include technically-recoverable conventional and unconventional resources and both non-associated and associated gas from oil fields below 15,000 feet. Bear in mind that each estimating group used different assessment methodologies and procedures including: geographic areas of coverage, entities assessed, definition of conventional versus unconventional resources, affiliation of province and regional experts, quantitative probability distributions and aggregations, assessment review process, method of subdividing resources by depth interval, and sources of data. For example, the Gas Research Institute (GRI) estimates include reserve growth for existing fields in their totals which have not been subdivided in their published reports. Other estimators reported totals for reserve growth separately. Refer to Dyman and Schmoker (in press) for a detailed discussion of the many areas in which these National petroleum assessments are different.

The GRI and National Petroleum Council (NPC) assessments were based on the GRI Hydrocarbon Supply Model, whereas the U.S. Geological Survey and Potential Gas Committee (PGC) assessments were based on a probabilistic analysis of geologically-based plays. The GRI total does not include Alaska deep gas because GRI did not subdivide Alaska data by depth. The GRI estimate, therefore, should be considered a minimum one. The NPC did not assess Alaska, and the PGC estimated only negligible gas in Alaska basins. Even if Alaska is excluded, the GRI estimate is still the largest (184 TCF; Fig. 5; Table 3).

Regional comparisons indicate significant differences in results. Even though the GRI estimate was the highest of the four groups, regional estimates, with the exception of the Gulf Coast Basin, are relatively low when compared to those of the other groups (Fig. 5). The U.S. Geological Survey Midcontinent Region estimate is noticeably low when compared to the others. Conversely, the U.S. Geological Survey Rocky Mountain Region estimate is noticeably high because of the inclusion of unconventional continuous-type plays (55.2 TCF). Variations in regional totals are partly due to differences in the way in which regions were defined geographically.

POTENTIAL ADDITIONAL RESOURCES AND AREAS OF FUTURE STUDYAn analysis of the U.S. Geological Survey 1995 National Oil and Gas Resource

Assessment reveals many areas for future study, some of which could result in greater estimates of undiscovered deep gas resources. One such area involves re-evaluating and assessing existing conventional and continuous-type plays that were too poorly understood to assess in 1995. For

12

the 1995 assessment, five deep continuous-type plays were identified but not assessed because of a lack of basic geologic and petroleum-related information (Table 2). These basin-centered gas plays could contain significant undiscovered technically-recoverable resources. In addition to these plays, others may exist that were not previously identified. Rocky Mountain basins such as the Raton, Albuquerque, Wind River, and Crazy Mountains Basins, California basins, and the Midcontinent rift are possible areas to investigate.

An additional 61 deep conventional plays are listed in Appendix A, but have no undiscovered non-associated gas resources attributed to them. We feel that it is important to recognize these plays, and have included them in our Appendix. These plays include those that: (1) are oil plays, (2) were severely risked in that no gas was ultimately estimated for them, or (3) have a maximum depth of 15,000 ft and have no gas resource assigned to them below that depth. Fifteen deep conventional oil plays were identified in Appendix A, and gas resources other than associated gas were not estimated for them (gas fraction = 0). An example play in this category is the Cook Inlet Late Mesozoic Oil Play (305). An additional fourteen deep conventional gas plays (gas fraction greater than zero) were highly risked (probability 0.1 or less; Appendix A) and were not assessed. An example play in this category is the hypothetical Older Tertiary Play (1704) of the Idaho Snake River Downwarp Province. Risking hypothetical plays is a subjective process, and assigning even a slightly lower risk (higher probability of resources) based on geologic information could result in additional estimated undiscovered gas resources. Twenty- three deep conventional plays in Appendix A were assigned a maximum play depth of 15,000 feet. Many of these plays are hypothetical gas plays, and depth information for them is poorly known. An example in this category is the Southwest Oregon Eocene Gas Play (410), which is also highly risked (0.1).

Recommendations for future investigations based on results of the U.S. Geological Survey 1995 National Petroleum Assessment include:

1. Re-evaluate the geologic characteristics and drilling histories of existing and potential deep hypothetical plays as more data becomes available. These plays could contribute to estimates of additional deep gas resources as more data becomes available.

2. Conduct geologic studies to determine the spatial relationships between deep conventional and continuous-type plays in some deep basins. Conventionally-trapped deep gas plays may grade into basin-centered, continuous-type gas plays down-dip in the Appalachian, Anadarko, Wind River, and other basins of the United States.

3. Economic analysis of deep gas accumulations, leading to the resource category ofeconomic, technically-recoverable, undiscovered gas. In this way the assessment will be further enhanced by the information necessary to subdivide resources into short, intermediate, and long-term categories based on economics.

4. Determine the existence and extent of continuous-type plays in basins for which they were not assessed previously. Continuous-type accumulations have been hypothesized for the Appalachian, Anadarko, and other basins (see Table 3).

Even though comparisons are difficult to make due to the many differences in procedures and methods by the different groups, the four estimates provide a range of values that can be used to develop National energy policy decisions.

13

REFERENCESBall, M.M., Henry, M.E., and Perry, W.J., Jr., 1995, Region 5-West Texas and eastern New

Mexico, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Bird, K.J., 1995, Region 1-Alaska, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Bird, K.J., Northern Alaska province, 1995, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Charpentier, R.R., 1995, Region 7 Midcontinent, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Dwights Energy Data, 1986, Petroleum Data System (through 1985): Available from Dwights Energy Data Corp., Oklahoma City, OK 73108.

Dyman, T.S., ed., 1992, Geologic controls and resource potential of natural gas in deepsedimentary basins in the United States: U.S. Geological Survey Open-File Report 92- 524, 287 p.

Dyman, T.S., Spencer, C.W., Baird, J., Obuch, R., and Nielsen, D., in press, Geologic characteristics of deep natural gas resources based on data from significant fields and reservoirs, in Dyman, T.S., ed., Geologic controls and resource potential of natural gas in deep sedimentary basins in the United States: U.S. Geological Survey Bulletin 2146.

Dyman, T.S., 1995, Deep natural gas reservoirs and plays in the United States, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Dyman, T.S., and Schmoker, J.W., in press, Comparison of National petroleum assessments: U.S. Geological Survey Open-File Report.

Gas Research Institute, 1995, GRI baseline projection of U.S. energy supply and demand 1996 edition: Gas Research Institute, 71 p.

Gautier, D.L., and Dolton, G.L., 1995, Methodology for assessment of undiscovered conventional accumulations, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 Nationalassessment of United States oil and gas resources results, methodology, and supporting data: U.S. Geological Survey Digital Data Series 30.

Houghton, J.C., Dolton, G.L., Mast, R.F., Masters, C.D., and Root, D.H., 1993, U.S. Geological Survey estimation procedure for accumulation size distributions by play: American Association of Petroleum Geologists Bulletin: v. 77, no. 3, p. 454-466.

Mast, R.F., Dolton, G.L., Crovelli, R.A., Root, D.H., Attanasi, E.D., P.E. Martin, L.W. Cooke, G.B. Carpenter, W.C. Pecora, and M.B. Rose, 1989, Estimates of undiscovered conventional oil and gas resources in the United States-a part of the Nation's energy endowment: U.S. Geological Survey and Minerals Management Service special publication, 44 p.

National Petroleum Council, 1992, The potential for natural gas in the United States-executive summary: National Petroleum Council, 24 p., with appendices.

NRG Associates Inc., 1990, The significant oil and gas fields of the United States (throughDecember 31, 1988): Available from Nehring Associates, Inc., P.O. Box 1655, Colorado Springs, CO 80901.

Peterson, J.A., and Grow, J.A., 1995, Colorado Plateau and Basin and Range, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum

14

assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Petroleum Information Corporation, 1991, Well History Control System (through December 1991): Available from Petroleum Information Corporation, 4100 East Dry Creek Road, Littleton, CO 80122.

Potential Gas Committee, 1995, Potential Supply of natural gas in the United States: Potential Gas Agency, Colorado School of Mines, Golden, CO., 130 p.

Rice, D.D., Schenk, C.J., Schmoker, J.W., Fox, I.E., Clayton, J.L., Dyman, T.S., Higley, D.K., Keighin, C.W., Law, B.E., and Pollastro, R.M., 1992, Potential for deep natural gas resources in eastern Gulf of Mexico, in Malone, R.D., Shoemaker, H.D., and Byrer, C.W., eds., Proceedings of the natural gas research and development contractors review meeting: U.S. Department of Energy, Morgantown Energy Technology Center Report 92/6125, p. 151-166.

Root, D.H., and Attanasi, E.D., 1993, Small fields in the National oil and gas assessment: American Association of Petroleum Geologists Bulletin, v. 77, no. 3, p. 485-490.

Ryder, R.T., 1995, Region 8-Eastern, 1995, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Schenk, C.J., 1995, Region 6~Gulf Coast, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Schmoker, J.W., 1995, Method for assessing continuous-type (unconventional) hydrocarbon accumulations, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Schmoker, J.W., and Oscarson, S.A., 1995, Descriptions of continuous-type (unconventional) plays of the U.S. Geological Survey 1995 National assessment of United States oil and gas resources: U.S. Geological Survey Open-File Report 95-75B, 44 p.

Spencer, C.W., 1995, Region 4 Rocky Mountains and northern Great Plains, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L., eds., 1995 National petroleum assessment of United States oil and gas resources on CD-ROM: U.S. Geological Survey Digital Data Series 30.

Takahashi, K.I., and Cunningham, K.I., 1987, Map showing wells drilled for oil and gas deeper than 15,000 feet (about 4,600 m) in the conterminous United States and offshore: U.S. Geological Survey Oil and Gas Investigations Map OM-220, scale 1:5,000,000.

U.S. Geological Survey National Oil and Gas Resource Assessment Team, 1995, 1995 National assessment of United States oil and gas resources: U.S. Geological Survey Circular 1118, 20 p.

Vidas, E.H., Hugman, R.H., and Haverkamp, D.S., 1993, Guide to the hydrocarbon supply model: 1993 update: Gas Research Institute Strategic Planning and Analysis Division 93/0454, 250 p.

Woods, T.J., 1993, The long-term trends in U.S. gas supply and prices: 1993 edition of the GRI baseline projection of U.S. energy supply and demand to 2010: Gas Research Institute, 92 p.

Tabl

e 1.

Sum

mar

y of

sig

nific

ant r

eser

voirs

equ

al to

or g

reat

er th

an 1

4,00

0 fe

et in

dep

th in

maj

or d

eep

basi

n ar

eas

of U

.S.

Bas

ed o

n da

ta fr

om

NR

G A

ssoc

iate

s Si

gnifi

cant

Fie

ld F

ile (

NR

G A

ssoc

iate

s, 1

990)

and

com

pile

d in

Dym

an (

1995

). Si

gnif

ican

t res

ervo

irs c

onta

in u

ltim

ate

reco

vera

ble

reso

urce

s gr

eate

r tha

n 6

BC

F of

gas

(eq

uals

1 M

MB

O).

Rec

.= r

ecov

erab

le; r

es.=

rese

rvoi

rs; t

otal

of o

f 377

res

ervo

irs u

sed

for U

.S.

Cum

ulat

ive

prod

uctio

n an

d kn

own

reco

vera

ble

natu

ral g

as in

trill

ions

of c

ubic

fee

t (TC

P). C

umul

ativ

e ga

s= c

umul

ativ

e na

tura

l gas

pro

duct

ion

thro

ugh

1988

; kno

wn

rec.

= kn

own

reco

vera

ble

natu

ral g

as (

cum

ulat

ive

prod

uctio

n an

d re

serv

es);

stra

t= s

tratig

raph

ical

ly tr

appe

d re

serv

oirs

; car

b=

carb

onat

e re

serv

oirs

. Per

cent

ages

do

not a

lway

s ad

d up

to 1

00 p

erce

nt d

ue to

roun

ding

.

Loca

tion

Num

ber o

f re

serv

oirs

and

(p

erce

nt o

f tot

al

num

ber)

(377

)

Cum

ulat

ive

gas

prod

uctio

n an

d (p

erce

nt o

f tot

al

gas)

(21

.4 T

CP)

Kno

wn

rec.

ga

s an

d (p

erce

nt o

f to

tal g

as)

(33.

2 TC

F^)

Stra

tigra

phic

an

d lit

holo

gic

info

rm at

ion

Com

men

ts

Roc

ky M

ts

22 (

6)%

Ana

dark

o B

asin

Perm

ian

Bas

in

0.4

(2)%

84 (

22)%

89 (

24)%

2.4(

11)%

12.4

(58

)%

Gul

f Coa

st

174(

46)%

6.

2(29

)%

Bas

in

2.2

(7)%

2.8

(8)%

15.1

(45

)%

12.8

(39

)%

Will

isto

n 5(

1)%

0.

1 (<

!)%

<0

.1 (

<1)9

B

asin

Cal

iforn

ia/

3 (<

!)%

<0

.1 (

<!)%

0.

3 (1

)%

Ala

ska

Jura

ssic

and

Cre

tace

ous

elas

tic re

serv

oirs

and

Pa

leoz

oic

mix

ed c

arb/

clas

tic

rese

rvoi

rs

Mos

tly a

cla

stic

bas

in.

Som

e C

ambr

ian-

Silu

rian

carb

onat

e pr

oduc

tion

Mid

dle

Pale

ozoi

c m

ixed

cl

astic

/car

b. r

eser

voirs

an

d Lo

wer

Pal

eozo

ic

mos

tly c

arbo

nate

res.

Terti

ary

rese

rvoi

rs

mos

tly c

last

ic; J

uras

sic

and

Cre

tace

ous

rese

rvoi

rs

mix

ed c

arbo

nate

/cla

stic

Ord

ovic

ian

Red

Riv

er

dolo

miti

c re

serv

oirs

Terti

ary

clas

tic

rese

rvoi

rs

Dee

p ga

s m

ostly

fro

m

Uta

h-W

yom

ing

thru

st

belt.

Pot

entia

l fr

om

Han

na a

nd W

ind

Riv

er

basi

ns

65%

of r

eser

voirs

pro

duce

fr

om P

enns

ylva

nian

st

rata

67 o

ut o

f 89

rese

rvoi

rs o

ccur

in

Dev

onia

n or

old

er ro

cks.

Pe

rmia

n re

serv

oirs

are

stra

t- ig

raph

ical

ly-tr

appe

d

37%

of d

eep

rese

rvoi

rs a

re

Terti

ary

Stru

ctur

ally

trap

ped

Stru

ctur

al a

nd

stra

tigra

tigra

phic

trap

s

Tabl

e 2.

D

eep

cont

inuo

us-ty

pe g

as p

lays

of t

he U

.S. G

eolo

gica

l Sur

vey

1995

Nat

iona

l Pet

role

um A

sses

smen

t. In

clud

es b

oth

asse

ssed

and

una

sses

sed

play

s w

ith m

axim

um d

epth

s of

15,

000

feet

or g

reat

er.

Mea

n va

lue

of u

ndis

cove

red

gas

reso

urce

s on

ly f

or

that

por

tion

of p

lay

at o

r bel

ow 1

5,00

0 fe

et; i

n bi

llion

s of

cub

ic f

eet (

BC

F).

Min

imum

(m

in),

med

ian

(med

), an

d m

axim

um

(max

) de

pth

for a

sses

sed

play

s in

feet

. R

efer

to S

chm

oker

and

Osc

arso

n (1

995)

for

geo

logi

c de

scri

ptio

n of

eac

h pl

ay.

Prov

ince

num

ber

nam

ePl

av n

ame

(num

ber)

Dep

th

min

m

edU

ndis

cove

red

max

___gas

(B

CF)

04--

Wes

tern

Ore

gon-

Was

h.

05-E

aste

rn O

rego

n-W

ash.

14-L

os A

ngel

es B

asin

20~U

inta

-Pic

eanc

e B

asin

34 B

ig H

orn

Bas

in

35-W

ind

Riv

er B

asin

37--

Sout

hwes

tern

Wom

ing

58-A

nada

rko

Bas

in

Will

amet

te-P

uget

Sou

nd B

asin

-Cen

tere

d G

as (

412)

Col

umbi

a B

asin

-Bas

in-C

ente

red

Gas

(50

3)

Dee

p, O

verp

ress

ured

Fra

ctur

ed R

ocks

of t

he

Cen

tral S

yncl

ine

(140

8)

Dee

p Sy

nclin

al U

inta

Mes

aver

de (2

020)

Bas

in-C

ente

r Gas

(340

4)

Bas

in-C

ente

r Gas

(350

5)

Gre

en R

iver

Bas

in-C

love

rly-F

ront

ier (

3740

) G

reen

Riv

er B

asin

-Mes

aver

de (3

741)

G

reen

Riv

er B

asin

-Lew

is (

3742

) G

reen

Riv

er B

asin

-For

t Uni

on (

3744

)

Woo

dfor

d/C

hatta

noog

a/A

rkan

sas

Nov

acul

ite

ofM

idco

ntin

ent(

5811

)

not a

sses

sed

9,50

0 13

,000

17,5

00

2,63

6

not a

sses

sed

15,0

00

18,0

00

24,0

00

570

not a

sses

sed

not a

sses

sed

11,5

00

17,0

008,

500

15,0

0010

,500

12

,000

9,50

0 10

,200

not a

sses

sed

22,0

00

25,0

0421

,000

25

,848

19,0

00

4,26

517

,000

95

Tota

l58

,418

Tabl

e 3.

Est

imat

es o

f und

isco

vere

d na

tura

l gas

by

regi

on f

or d

epth

s of

15,

000

feet

or

grea

ter f

rom

rec

ent N

atio

nal P

etro

leum

Cou

ncil

(NPC

), Po

tent

ial G

as C

omm

ittee

(PG

C),

U.S

. Geo

logi

cal S

urve

y (U

SGS)

, and

Gas

Res

earc

h In

stitu

te (

GR

I) a

sses

smen

ts.

Dat

a ar

e m

ean

estim

ates

, exc

ept f

or P

GC

col

umn

whe

re th

ey r

epre

sent

mos

t lik

ely

valu

es.

Reg

iona

l bou

ndar

ies

vary

for

eac

h as

sess

men

t. G

as in

bill

ions

of c

ubic

fee

t (B

CF)

. D

ata

incl

ude

asso

ciat

ed g

as f

rom

oil

accu

mul

atio

ns a

nd n

on-a

ssoc

iate

d ga

s. O

nsho

re re

gion

s an

d st

ate

wat

ers

only

. O

nly

tota

l col

umn

avai

labl

e fo

r G

RI

and

PGC

ass

essm

ents

. U

ncon

vent

iona

l gas

her

e pr

imar

ily in

clud

es g

as in

lo

w-p

erm

eabi

lity

(tigh

t) sa

ndst

ones

. U

ndis

cove

red

volu

mes

of g

as u

nder

diff

eren

t cat

egor

ies

may

var

y du

e to

the

way

in w

hich

a

cate

gory

is d

efin

ed.

For

exam

ple,

the

U.S

. Geo

logi

cal S

urve

y es

timat

e in

clud

es c

ontin

uous

-typ

e sa

ndst

ones

bas

ed o

n ge

olog

ic c

riter

ia,

whe

reas

the

PGC

, GR

I, an

d N

PC id

entif

ies

tight

san

dsto

nes

base

d on

Fed

eral

Ene

rgy

Reg

ulat

ory

Com

mis

sion

-des

igna

ted

crite

ria.

Res

ourc

e es

timat

es b

ased

on

curr

ent t

echn

olog

y ca

se o

nly.

Plu

s si

gn (

+) i

ndic

ates

that

GR

I dat

a fo

r Ala

ska

not b

roke

n ou

t by

dept

h an

d no

t inc

lude

d (to

tal G

RI

Ala

ska

reso

urce

is 1

21,4

53 B

CF)

. Let

ter t

indi

cate

s th

at re

sour

ce e

stim

ates

iden

tifie

d fo

r des

igna

ted

regi

on

tabu

late

d el

sew

here

. Ast

eris

k (*

) in

dica

tes

that

GR

I to

tal i

nclu

des

natu

ral g

as a

ttrib

uted

to re

serv

e gr

owth

in e

xist

ing

field

s. G

as

volu

mes

roun

ded

to n

eare

st B

CF.

Ind

ivid

ual e

stim

ates

may

or m

ay n

ot in

clud

e St

ate

offs

hore

wat

ers.

USG

S es

timat

es d

o no

t inc

lude

un

disc

over

ed g

as f

rom

sm

all f

ield

s (le

ss th

an 6

BC

FG).

Reg

ion

Nat

iona

l Pet

role

um

Cou

ncil

(NPC

)19

921

Ala

ska

Paci

ficR

ocky

Mts

.C

olor

ado

Plat

eau

W. T

exas

-E.

New

Mex

.G

ulf C

oast

Mid

cont

inen

tEa

ster

n

Con

ven­

tiona

lU

ncon

v­en

tiona

lTo

tal

not a

sses

sed

4,25

811

,728

t

12,3

2825

,124

16,4

142,

159

08,

992 t 0

917

5,47

1 0

4,25

820

,721

t

12,3

2826

,041

21,8

852,

159

Pote

ntia

l Gas

U

.S.

Geo

logi

cal

Com

mitt

ee (

PGC

) Su

rvey

(U

SGS)

1995

1 Tota

l 01,

450

36,2

34t t

44,6

0035

,204

12.8

002

1995

1

Con

ven­

tiona

l

17,9

36 550

1,94

613

0

4,70

527

,439

2,26

429

4

Unc

onv­

entio

nal

02,

636

55,2

12 570 0 0 0 0

Tota

l

17,9

353,

186

55,1

58 700

4,42

627

,404

2,26

429

4

Gas

Res

earc

h In

stitu

te (

GR

I)*

1995

1 Tota

l +4,

916

44,3

03t

32,7

3466

,034

34,1

332,

133

Tota

l72

,011

15

,381

87

,392

130,288

55,264

58,4

18

113,681

184,

253

1 Ref

er to

Nat

iona

l Pet

role

um C

ounc

il (1

992)

, Pot

entia

l Gas

Com

mitt

ee (

1995

), G

autie

r an

d ot

hers

(19

95),

Woo

ds (

1993

), V

idas

and

ot

hers

(19

93),

and

Gas

Res

earc

h In

stitu

te (

1995

) fo

r det

aile

d ex

plan

atio

ns o

f ass

essm

ents

.

18

Blake Plateau basin

Figure 1. Generalized map of conterminous United States and Alaska showing basinscontaining rocks greater than 15,000 feet (about 4,600 m) deep. Shaded areas represent entire basins. WY-UT-DD = Wyoming- Utah-Idaho. Federal offshore areas identified but not discussed in report. Some small areas and basins listed in Appendix A are not identified on the map.

19

Ultimate recoverable production from deep significant fields

Permian basin 45%

Gulf Coast 39%

8%7%\(2-8) (2.2)

Williston basin

Anadarko basin

Rocky Mountain basinsCalifornia &

Alaska basins1%

(0.3)

Figure 2. Pie chart illustrating the distribution of known ultimate recoverable gas from deep significant fields by region in the U.S. Numbers in parentheses represent estimates in trillions of cubic feet of natural gas (TCFG) taken from NRG Associates file for reservoirs below 14,000 feet in the U.S. (NRG Associates, 1990). Percent for each region based solely on NRG Associates data. Small fields not included. Refer to Table 1 for data summary.

20

Figure 3. Map of United States showing province and region boundaries for U.S. Geological Survey 1995 National petroleum assessment (from U.S. Geological Survey National Oil and Gas Resource Assessment Team, 1995).

21

CO LLJ O DC Z> O CO LU DCCO <OQ LU DC LU^> *- ^ ® O <D

PQ D

-> O

Q- c/> LU C LU 2

LU

*

COLU

<LU

60-i

54-

48-

42-

36-

30-

Rocky Mountains & Northern Great Plains

:= 24-

18-

12-

REGION

Figure 4. Histogram illustrating distribution of estimates of deep undiscovered technically- recoverable gas by region in the United States for the 1995 U.S. Geological Survey National assessment of oil and gas resources. Shaded portion included resources attributed to continuous-type plays for each region. Resources include both non- associated gas and associated gas from oil fields. Mean estimate shown. Refer to Table 2 for data summary.

22

70-n

JIB NPC(1992)

H PGC(1995) USGS(1995)

EZ3 GRI(1995)

t = assessed as part of another region

AlaskaN. Gr. Plains Plateau E. N. Mexico

Gulf Coast

Eastern

Figure 5. Histogram illustrating distribution of estimated deep undiscovered technically- recoverable gas by region in the United States for recent National petroleum assessments including the National Petroleum Council (1992), Potential Gas Committee (1995), U.S. Geological Survey (1995), and Gas Research Institute (1995). Resources include both non-associated gas and associated gas from oil fields. Refer to Table 3 for data summary and explanation of differences.

App

endi

x A

. U

ndis

cove

red

tech

nica

lly-r

ecov

erab

le d

eep

gas

reso

urce

s fo

r con

vent

iona

l pet

role

um p

lays

ext

endi

ng to

dep

ths

equa

l to

or g

reat

er th

an 1

5,00

0 fe

et

in th

e U

.S.

Onl

y a

part

of s

ome

play

s oc

curs

bel

ow 1

5,00

0 fe

et.

Play

def

initi

ons

com

pile

d fr

om d

ata

by p

rovi

nce

geol

ogis

ts (

Gau

tier

and

othe

rs,

1995

). C

, co

nfirm

ed p

lay

with

kno

wn

prod

uctio

n; H

, hyp

othe

tical

pla

y; m

in, m

inim

um d

epth

of p

lay;

med

, med

ian

dept

h of

pla

y; m

ax, m

axim

um d

epth

of p

lay;

Pro

b,

the

prob

abili

ty o

f und

isco

vere

d ac

cum

ulat

ions

of a

t lea

st 6

BC

F of

gas

or

1 M

MB

O in

pla

y w

here

pla

y is

hyp

othe

tical

; G

as f

ract

ion,

fra

ctio

nal d

istri

butio

n of

un

disc

over

ed n

on-a

ssoc

iate

d ga

s ac

cum

ulat

ions

exp

ecte

d in

this

pla

y w

here

0.0

indi

cate

s an

oil

play

and

1.0

indi

cate

s a

non-

asso

ciat

ed g

as p

lay.

Bla

nk in

dica

tes

no d

ata

avai

labl

e. R

efer

to T

able

2 f

or u

ndis

cove

red

reso

urce

s in

unc

onve

ntio

nal c

ontin

uous

-type

pla

ys.

Que

stio

n m

ark

indi

cate

s hi

ghly

inte

rpre

tive

or

spec

ulat

ive

data

. Pl

ay n

umbe

rs c

orre

spon

d to

pla

y nu

mbe

rs in

Gau

tier a

nd o

ther

s (1

995)

. N

on-a

ssoc

iate

d ga

s on

ly l

iste

d fo

r por

tion

of p

lay

belo

w 1

5,00

0 fe

et

and

in b

illio

ns o

f cub

ic f

eet.

Whe

re n

on-a

ssoc

iate

d ga

s vo

lum

es a

re z

ero,

pla

y m

ay b

e en

tirel

y an

oil

play

, pla

y m

ay b

e hi

ghly

ris

ked

(res

ourc

es u

nlik

ely)

, or

max

imum

dep

th o

f pla

y is

15,0

00 fe

et a

nd u

ndis

cove

red

reso

urce

s w

ere

allo

cate

d to

sha

llow

er d

epth

s. N

umbe

rs in

par

enth

eses

afte

r reg

ion

and

prov

ince

nam

es

repr

esen

t tot

al u

ndis

cove

red

tech

nica

lly-r

ecov

erab

le c

onve

ntio

nal g

as v

olum

es w

here

firs

t num

ber i

s no

n-as

soci

ated

gas

, sec

ond

num

ber i

s as

soci

ated

gas

from

oi

l fie

lds,

and

third

num

ber

afte

r eq

ual s

ign

(onl

y fo

r reg

ion)

is to

tal g

as (

BC

FG).

Reg

ion

and

Prov

ince

Play

num

ber

and

nam

eSt

atus

Pro

bm

mD

epth

(fee

t) m

edm

axG

as

frac

tion

Non

-ass

oc.

gas

vol.

Reg

ion

1-A

lask

a (1

7,66

4.4;

Nor

ther

n A

lask

a (1

7,58

8.4;

127

.8)

271.

4=17

,935

.8)

102

Turb

idite

103

Bar

row

Arc

h B

eauf

ortia

n10

4 B

arro

w A

rch

Elle

smer

ian

105

Elle

smer

eian

-Bea

ufor

tian

Cla

stic

s10

6 Li

sbur

ne10

7 Li

sbur

ne U

ncon

form

ity10

8 En

dico

tt10

9 Fo

ld B

elt

110

Wes

tern

Thr

ust B

elt

111

East

ern

Thr

ust B

elt

C C C C H H H C H C

1.0

1.0

1.0

1.0

0.5

0.6

1.0

1.0

0.2

1.0

500

1500

2200

2000

9000

8500

9500 100

1000

2000

8000

7000

10000

1000

025

000

2500

025

000

4000

1000

013

000

25000

1500

015

300

2600

030000

30000

30000

25000

35000

2500

0

0.2

0.3

0.0

1.0

1.0

gas

gas

0.8

0.6

0.7

433.

50.

00.

01,

631.

83,

435.

30.

00.

02,

340.

267

9.2

9,06

8.4

to U)

Cen

tral

Ala

ska

(0.0

; 0.

0)

Sout

hern

Ala

ska

(76.

0; 1

43.6

)

201

Cen

tral A

lask

a C

enoz

oic

Gas

H

0.

120

3 C

entra

l Ala

ska

Pale

ozoi

c O

il H

0.

120

4 K

andi

k Pr

e-M

id C

reta

ceou

s St

rata

H

0.

1

301

Ala

ska

Peni

nsul

a M

esoz

oic

H

<0.1

20

0030

2 A

lask

a Pe

nins

ula

Terti

ary

H

<0.1

50

0030

3 C

ook

Inle

t-Bel

uga-

Ster

ling

Gas

C

1.0

2000

304

Coo

k In

let H

emlo

ck-T

yone

k O

il C

1.0

5000

305

Coo

k In

let L

ate

Mes

ozoi

c O

il .

H

<0.1

307

Cop

per R

iver

Mes

ozoi

c O

il >H

<0

.130

8 G

ulf o

f Ala

ska

Yak

atag

a Fo

ld B

elt

H

0.7

030

9 G

ulf o

f Ala

ska

Yak

utat

For

elan

d H

0.

4 16

00

4000

1000

0

1500

0?

gas

1500

0+ o

il 15

000+

gas

?

2000

0 ga

s 15

000+

gas

20

000

1.0

1800

0 0.

0 15

000

oil

1500

0 oi

l 28

000+

oil

2800

0+ o

il

0.0

0.0

0.0

0.0

0.0

76.0

0.

0 0.

0 0.

0 0.

0 0.

0

Prov

ince

nam

e

Reg

ion

2-P

acif

ic

(208

.3;

341.

3=

549.

Wes

tern

Ore

gon

and

Was

hing

ton

(15.

2; 3

.0)

East

ern

Was

hing

ton -

Ore

gon

(0.0

; 0.0

)

Nor

ther

n C

alifo

rnia

Coa

stal

(0.

0; 0

.0)

Sono

ma-

Live

rmor

e B

asin

(0.

6; 0

.1)

Sacr

amen

to B

asin

(94

.7; 0

.0)

San

Joaq

uin

Bas

in (

0.0;

270

.9)

Cen

tral

Coa

stal

Bas

ins

(0.0

; 0.

0)

Ven

tura

Bas

in (

97.8

; 67.

3)

Reg

ion

3-C

olor

ado

Pla

teau

an

d B

asin

Idah

o Sn

ake

Riv

er D

ownw

arp

(2.1

; 0.0

)

Play

num

ber

and

nam

e St

atus

Pro

b

6)40

3 Pu

get L

owla

nd D

eep

Gas

404

Tofin

o-Fu

ca B

asin

Gas

405

Wes

tern

Was

hing

ton

Mel

ange

410

Sout

hwes

t Ore

gon

Eoce

ne G

as

501

Nor

thw

este

rn C

olum

bia

Plat

eau

Gas

703

Sarg

ent/H

ollis

ter O

il an

d G

as

801

Sono

ma-

Live

rmor

e

902

Sout

hern

For

bes-

Kio

ne90

3 W

este

rn W

inte

rs th

roug

h D

omin

gene

1003

Low

er B

aker

sfie

ld A

rch

1004

Wes

t Sid

e Fo

ld B

elt S

ourc

ed b

y Po

st-

Low

er M

ioce

ne R

ocks

1005

Wes

t Sid

e Fo

ld B

elt S

ourc

ed b

y Pr

e-M

iddl

e M

ioce

ne R

ocks

1008

Tej

on P

latfo

rm10

09 S

outh

ern

End

Thr

ust S

alie

nt10

11 D

eep

Ove

rpre

ssur

ed F

ract

ured

Roc

ksof

Wes

t Sid

e Fo

ld a

nd O

verth

rust

Bel

t

11 04

La

Hon

da O

il

1301

Pal

eoge

ne -

Ons

hore

1302

Neo

gene

- O

nsho

re13

04 C

reta

ceou

s13

11 P

aleo

gene

-Off

shor

e St

ate

Wat

ers

and

Ran

ge

(127

.0;

2.7=

12

9.7)

1701

Mio

cene

Lac

ustri

ne (L

ake

Bru

neau

)17

03 P

re-M

ioce

ne17

04 O

lder

Ter

tiary

H H H H H C C H C C C C C C H-

C C C H C H H H

0.1

0.2

0.5

0.1

0.6

1.0

1.0

0.4

1.0

1.0

1.0

1.0

1.0

1.0

cO.l 1.0

1.0

1.0

0.2

0.1

0.1

Dep

th (f

eet)

min

m

ed

1000

050

010

050

0

500

1000

1000

4000

2000

5600 80

0

300

500

2000

1800

0 0

1000 500

5000

4000

1000

0

1500

060

0090

0030

00

8000

2000

6000

8000

7000

8500

9000

9000

6000

9000

1800

7000

8000

7000

6000

1500

0

max

2000

020

000

1800

015

000

1500

0

1500

0

1600

0

2000

016

000

1800

0

1800

0

2200

015

000

1600

0

2500

0

1500

0

2000

020

000

1500

0+15

000+

1500

015

000

2500

0

Gas

fr

actio

n

1.0

1.0

0.0

1.0

1.0

0.5

0.5

1.0

1.0

0.0

0.0

0.0

0.0

0.0

gas

0.0

0.4

0.0

gas?

gas

0.6

0.6

0.9

Non

-ass

oc.

gas

volu

me

13.4 1.8

0.0

0.0

0.0

0.0

0.6

57.2

37.5 0.0

to0.

0 £

0.0

0.0

0.0

0.0

0.0

25.6 0.0

0.0

72.2 2.1

0.0

0.0

Prov

ince

nam

e

Wes

tern

Gre

at B

asin

(1.

2; 0

.0)

East

ern

Gre

at B

asin

(41

.8;

1.7)

Uin

ta-P

icea

nce

Bas

in (

7.9;

1.0

)

Para

dox

Bas

in (

6.5;

0.0

)

Alb

uque

rque

Bas

in-S

ame

Fe R

ift (

50.2

; 0.0

)

Nor

ther

n A

rizon

a (1

7.3;

0.0

)

Sout

hern

Ari

zona

~SW

New

Mex

ico

(0.0

; 0.0

)

Sout

h-C

entra

l New

Mex

ico

(0.0

; 0.0

)

Reg

ion

4-R

ocky

M

ount

ains

(1

,859

.2;

Mon

tana

Thr

ust B

elt (

263.

7; 0

.1)

Play

num

ber

and

nam

e St

atus

Pr

ob

1801

Hor

nbro

ok B

asin

-Mod

oc P

late

au18

03 P

erm

ian-

Tria

ssic

Sou

rce

Roc

ksN

orth

wes

tern

Nev

ada

and

East

Cen

tral a

nd E

aste

rn O

rego

n18

04 C

reta

ceou

s So

urce

Roc

ks, N

orth

­w

este

rn N

evad

a18

05 N

eoge

ne S

ourc

e R

ocks

, Nor

thw

este

rnN

evad

a an

d Ea

ster

n C

alifo

rnia

1902

Lat

e Pa

leoz

oic

1905

You

nger

Ter

tiary

Bas

ins

1906

Lat

e Pa

leoz

oic-

Mes

ozoi

c (C

entra

lN

evad

a) T

hrus

t Bel

t19

07 S

evie

r Fro

ntal

Zon

e

2014

Bas

in M

argi

n Su

bthr

usts

2101

Bur

ied

Faul

t Blo

cks,

Old

erPa

leoz

oic

2104

Per

mia

n-Pe

nnsy

lvan

ian

Mar

gina

lC

last

ic21

05 S

alt A

ntic

line

Flan

k

2301

Alb

uque

rque

Bas

in23

05 S

an J

uan

Sag

2403

Lat

e Pr

oter

ozoi

c (C

huar

-Sou

rced

)an

d L

ower

Pal

eozo

ic

2501

Ala

mo

Hue

co B

asin

2502

Ped

rego

sa B

asin

2602

Oro

gran

de B

asin

2603

Mes

illa-

Mim

bres

Bas

ins

86.9

= 1,

946.

1)27

01 I

mbr

icat

e T

hrus

t Gas

2704

Hel

ena

Salie

nt G

as27

06 T

ertia

ry B

asin

s O

il an

d G

as

H H H H H H H H C H C H H H H H H H C H H

0.1

0.2

0.1

0.1

0.2

0.2

0.4

0.1 1.0

0.4

1.0

0.5

0.6

0.3

0.1

0.1

<0.1

<0.1

0.3

0.5

0.3

Dep

th (f

eet)

min

m

ed45

0050

00

4500

4500

3000

3000

6500

6000

6000

3000

3000

8000

3000

6000

1500

5000

2000

5000

3000 500

2000

9000

1000

0

9000

1200

0

8000

1200

012

000

1400

0

9000

7000

5000

1200

070

00

9000

1200

010

000

1000

014

000

1200

090

0080

00

max

1500

025

000

1500

0

2500

0

2000

0

2000

020

000

2000

0

1500

0

2000

015

000

2000

015

000

2000

0

2500

017

000

2400

024

000

1900

020

000

1600

0

Gas

fr

actio

n0.

90.

5

0.1

gas?

0.2

0.0

gas

0.6

0.4

0.8

0.7

0.8

0.0

0.5

0.4

0.4

0.5

0.4

0.95

1.0

0.8

Non

ass

oc.

gas

volu

me

0.0

1.2

0.0

0.0

3.0

4.1

0.0

34.7 7.9 °'°

S

6.5

0.0

50.2 0.0

17.3 0.0

0.0

0.0

0.0

256.

36.

90.

5

Prov

ince

nam

e

Sout

hwes

t Mon

tana

(30

.2;

0.0)

Will

isto

n B

asin

(13

.4;

0.0)

Pow

der R

iver

Bas

in (

0.0;

0.4

)

Big

Hor

n B

asin

(58

.4;

0.0)

Win

d R

iver

Bas

in (

131.

3; 2

.8)

Wyo

min

g T

hrus

t Bel

t (11

61.3

; 61

.0)

Sout

hwes

tern

Wyo

min

g (1

53.2

; 22.

6)

Play

num

ber

and

nam

e St

atus

Pro

b

2901

Cra

zy M

ount

ains

and

Lak

e B

asin

sC

reta

ceou

s G

as29

04 B

earto

oth

Fron

tal O

il an

d G

as29

07 T

ertia

ry B

asin

s O

il an

d G

as

3102

Red

Riv

er (O

rdov

icia

n)31

06 P

ost M

adis

on th

roug

h Tr

iass

icC

last

ic31

07Pr

e-R

edR

iver

Gas

3301

Bas

in M

argi

n Su

bthr

ust

3304

Upp

er M

inne

lusa

San

dsto

ne

3401

Bas

in M

argi

n Su

bthr

ust

3403

Dee

p B

asin

Stru

ctur

e

3501

Bas

in M

argi

n Su

bthr

ust

3503

Dee

p B

asin

Stru

ctur

e35

04 M

uddy

San

dsto

ne S

tratig

raph

ic35

06 P

hosp

horia

Stra

tigra

phic

3601

Mox

a A

rch

Exte

nsio

n36

02 C

raw

ford

-Mea

de T

hrus

ts36

03 N

orth

ern

Thru

sts

3604

Abs

arok

a Th

rust

3606

Hog

sbac

k Th

rust

3607

Cre

tace

ous

Stra

tigra

phic

3701

Roc

k Sp

rings

Upl

ift

3702

Che

roke

e A

rch

3703

Axi

al U

plif

t37

04 M

oxa

Arc

h-L

aBar

ge37

05 B

asin

Mar

gin

Ant

iclin

e37

06 S

ubth

rust

C H H C C C H C H C C C C H C H H C C C C C C C C H

1.0

0.4

0.2

1.0

1.0

1.0

0.4

1.0

0.5

1.0

1.0

1.0

1.0

0.8

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

0.8

Dep

th (f

eet)

min

m

ed

1000

4000 20

0

7000

1000

012

000

5000

5000

5000

8000

5000

1300

5000

2000

1000

045

0045

0050

0060

0010

00

1500

1500

2000

1200

4000

5000

5000

1200

012

000

1300

0

1300

0

1200

085

000

1200

014

000

1200

085

000

1200

011

000

1400

011

000

1000

010

000

1000

080

00

6000

5000

6000

1000

014

000

1200

0

max

2000

020

000

1800

0

1600

0

1600

016

000+

1500

015

000

2000

020

000

2000

024

000

1600

020

000

1800

017

500

1500

018

000

1700

017

000

1800

020

000

1500

018

000

3000

030

000

Gas

fr

actio

n

1.0

0.4

0.8

0.5

1.0

1.0

0.0

0.0

0.3

1.0

0.3

0.9

0.3

0.0

1.0

1.0

0.7

0.8

0.6

0.0

0.8

0.3

0.3

0.7

0.6

0.4

Non

-ass

oc.

gas

volu

me

26.0 2.7

1.5

0.0

0.0

13.4 0.0

0.0

10.1

48.3

32.7

86.8

11.8

&

0.0

953.

048

.7 0.0

118.

740

.8 0.0

18.4

18.4 0.0

45.5

44.3

26.6

Prov

ince

nam

e Pl

ay n

umbe

r an

d na

me

Stat

us

Prob

Reg

ion

5-W

est

Tex

as

and

Eas

tern

N

ew

Mex

ico

(4,6

98.2

; 6.

3=

4,70

4.5)

Perm

ian

Bas

in (

4,40

8.5;

6.3

) 44

01 P

re-P

enns

ylva

nian

, Del

awar

e-V

al V

erde

Bas

ins

4402

Pre

-Pen

nsyl

vani

an, C

entra

lB

asin

Pla

tform

4404

Low

er P

enns

ylva

nian

(B

end)

Sand

ston

e44

06 U

pper

Pen

nsyl

vani

an, N

orth

wes

tern

and

East

ern

Shel

ves,

Nor

ther

nD

elaw

are

and

Mid

land

Bas

ins

and

Nor

ther

n C

entra

l Bas

in P

latf

orm

4412

Del

awar

e Sa

ndst

ones

Mar

atho

n T

hrus

t Bel

t (1 1

.0; 0

.0)

4601

Fro

ntal

Zon

e O

il an

d G

as

Reg

ion

6-G

uIf

Coa

st

(27,

382.

2;

56.3

= 27

,438

.5)

Wes

tern

Gul

f Bas

in (

19,1

08.1

; 6.

4)

4701

Hou

ston

Sal

t Dom

e Fl

ank

Oil

and

Gas

4702

Nor

phle

t Sou

th T

exas

Dee

p G

as47

03 S

mac

kove

r So

uth

Texa

s G

as47

04 C

otto

n V

alle

y W

este

rn G

ulf G

as a

ndO

il47

05 L

ower

Cre

tace

ous

Car

bona

te S

helf/

Shel

f Edg

e G

as a

nd O

il47

09 T

usca

loos

a D

eep

Sand

ston

e G

as47

10 W

oodb

ine

Sout

h A

ngel

ina

Flex

ure

Oil

and

Gas

4720

Low

er W

ilcox

Dow

ndip

Ove

r-pr

essu

red

Gas

4723

Upp

er W

ilcox

Dow

ndip

Ove

r-pr

essu

red

Gas

4724

Mid

dle

Eoce

ne S

ands

tone

s D

ownd

ipG

as47

27 Y

egua

Dow

ndip

Gas

4729

Jac

kson

Dow

ndip

Gas

4731

Vic

ksbu

rg D

ownd

ip G

as47

32 F

rio S

outh

Tex

as D

ownd

ip O

ilan

d G

as

C C C C C C C H C C C C C C C C C H C C

1.0

1.0

1.0

1.0

1.0

1.0

1.0

0.8

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

0.5

1.0

1.0

Dep

th (f

eet)

min

m

ed

8400

4000

8000

5000

5000

3500 25

014

000

1000

0

3000

6000

1200

0

7000

8000

8000

8000

8000

6000

7000

6000

1600

0

1000

0

1100

0

1100

0

1100

0

9000

1800

016

000

1200

0

1400

017

000

1400

0

1600

0

1600

0

1200

014

000

1400

014

000

1200

0

max

2400

0

1550

0

1650

0

1600

0

1600

0

1800

0

1600

022

000

2200

0

2000

0

2000

022

000

2000

0

2000

0

2200

0

1800

022

000

2200

022

000

1800

0

Gas

fr

actio

n

1.0

0.2

0.8

0.2

0.3

0.4

0.6

1.0

1.0

0.7

0.7

1.0

0.3

1.0

1.0

0.9

1.0

1.0

1.0

1.0

Non

-ass

oc.

gas

volu

me

2,33

7.8

0.0

278.

7

23.8

33.7

11.0

34.2

505.

663

5.9

83.0

881.

54,

800.

0

299.

3

1,82

0.4

3,36

8.8

211.

62,

117.

31,

252.

063

9.4

154.

3

Prov

ince

nam

ePl

ay n

umbe

r an

d na

me

Stat

us

Prob

D

epth

(fee

t) G

as

Non

-ass

oc.

_________m

in

med

m

ax

frac

tion

gas

volu

me

Wes

tern

Gul

f Bas

in c

ontin

ued

Lou

isia

na-M

iss.

Sal

t Bas

ins

(8,2

39.0

; 49

.9)

4735

Frio

SE

Texa

s/S.

Lou

isia

na

Mid

-dip

Gas

and

Oil

4736

Frio

SE

Texa

s/S.

Lou

isia

naD

ownd

ip G

as

4738

Ana

huac

San

dsto

ne G

as a

nd O

il47

40 L

ower

Mio

cene

Del

taic

San

dsto

ne

Gas

and

Oil

4741

Low

er M

ioce

ne S

lope

and

Fan

San

d­

ston

e G

as47

42 M

iddl

e M

ioce

ne R

uvia

l San

dsto

ne

Gas

and

Oil

4743

Mid

dle

Mio

cene

Del

taic

San

dsto

ne

Gas

and

Oil

4744

Upp

er M

ioce

ne F

luvi

al S

ands

tone

G

as a

nd O

il

4745

Upp

er M

ioce

ne D

elta

ic S

ands

tone

G

as a

nd O

il

4901

Pie

rcem

ent S

alt D

ome

Flan

ks O

il an

d G

as49

03 N

orph

let M

obile

Bay

Dee

p G

as49

04 N

orph

let W

iggi

ns -

Han

cock

Arc

h G

as49

05 N

orph

let S

alt B

asin

Oil

and

Gas

4906

Nor

phle

t Ala

bam

a U

pdip

Oil

4907

Nor

phle

t SE

Mar

gin

Jack

son

Dom

e Fl

ank

Dee

p G

as49

09 S

mac

kove

r Wig

gins

- B

aldw

in F

lank

s G

as49

10 S

mac

kove

r A

laba

ma/

Flor

ida

Perip

hera

l Fau

lt Z

one

Oil

and

Gas

4912

Sm

acko

ver S

alt B

asin

s G

as a

nd O

il49

13 S

mac

kove

r Jac

kson

Dom

e D

eep

Gas

49

18 H

ayne

svill

e Sa

lt B

asin

s G

as a

nd O

il49

20 G

ilmer

Lim

esto

ne G

as49

21 C

otto

n V

alle

y U

pdip

Oil

4922

Cot

ton

Val

ley

Salt

Bas

ins

Gas

49

25 H

osst

on U

pdip

Oil

C

1.0

6000

12

000

1600

0 0.

6 62

.0

C

1.0

8000

14

000

2000

0 1.

0 55

8.8

C

1.0

8000

15

000

2000

0 0.

7 23

6.6

C

1.0

3000

10

000

1600

0 0.

7 44

.1

C

1.0

8000

14

000

2000

0 1.

0 1,

123.

2

C

1.0

1000

10

000

1700

0 0.

8 68

.5

C

1.0

8000

14

000

2000

0 0.

8 13

1.9

C

1.0

1000

80

00

1600

0 0.

4 3.

5

C

1.0

4000

14

000

2000

0 0.

6 96

.8

C C H C H H C C C C C C C C C

1.0

1.0

0.6

1.0

0.5

0.5

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

4000

1700

0

1300

080

0080

00

2000

0

1200

0

1000

08000

20000

6000

1000

02000

8000

4000

1000

020

000

1700

012

000

1200

0

2200

0

1600

0

1500

012

000

21000

1400

014

000

1000

014

000

9000

1600

024

000

2100

017

000

1600

0

24000

2000

0

2000

018

000

2300

020

000

1800

018

000

20000

1600

0

0.7

1.0

1.0

0.0

0.0

1.0

1.0

0.3

0.6

1.0

0.9

1.0

0.0

1.0

0.0

31.9

5,259.6

233.3

213.4

0.0

111.

1

356.5

319.9

180.5

259.8

379.9

367.0

0.0

155.8

0.0

00

Prov

ince

nam

e

Flor

ida

Peni

nsul

a (0

.0;

0.0)

Reg

ion

7-M

idco

ntin

ent

(2,2

64.1

; 0.

0=Su

perio

r (8

5.5;

0.0

)

Ana

dark

o B

asin

(20

67.3

; 0.0

)

Sout

hern

Okl

ahom

a(1

07.8

; 0.0

)

Ark

oma

Bas

in (

3.5;

0.0

)

Reg

ion

Mic

higa

n

Play

num

ber

and

nam

e St

atus

Pr

ob

4926

Hos

ston

/Tra

vis

Peak

Sal

t Bas

ins

Gas

49

29 S

ligo/

Pette

t Sal

t Bas

ins

Gas

49

31 J

ames

Lim

esto

ne G

as

4933

Gle

n R

ose/

Rod

essa

Sal

t Bas

ins

Gas

49

35 P

alux

y D

ownd

ip G

as

5006

Woo

d R

iver

Dol

omite

Dee

p G

as

2,26

4.1)

5101

Pre

cam

bria

n M

idco

ntin

ent R

iftSy

stem

5801

Dee

p St

ruct

ural

Gas

5812

Dee

p St

ratig

raph

ic G

as58

27 W

ashe

s

6101

Dee

p G

as

6205

Arb

uckl

e th

roug

h M

isen

er B

asem

ent

Faul

t and

She

lf G

as62

06 C

rom

wel

l-Spi

ro-W

apan

ucka

Sub-

Cho

ctaw

Thr

ust G

as62

07 C

arbo

nife

rous

Tur

bidi

te T

hrus

t Bel

tG

as

C

C

C

C

C H H C C C C C C H

1.0

1.0

1.0

1.0

1.0

0.1

0.4

1.0

1.0

1.0

1.0

1.0

1.0

0.2

Dep

th (f

eet)

min

m

ed40

00

5000

80

00

3000

40

00

1400

0

5000

1300

013

000

500

1300

0

4000

7000

6000

1200

0 11

000

1100

0 10

000

1000

0

1600

0

1000

0

1700

015

000

9400

1500

0

8000

1200

0

1300

0

max

1800

0 16

000

1600

0 16

000

1600

0

1900

0

2500

0

4000

030

000

1500

0+

4000

0

1500

0

1500

0

2000

0

Gas

fr

actio

n1.

0 1.

0 ga

s?

1.0

1.0

oil?

0.6

1.0

1.0

0.8

1.0

1.0

1.0

1.0

Non

-ass

oc.

gas

volu

me

240 16

61 52

0 0 85

.8

.2

.0

.3

.0 .0 .5

770.

01,

297 0

107 0 0 3.3 .0 .8 .0 .0 .5

8-E

aste

rn

(293

.8;

0.0=

29

3.8)

Bas

in (

0.0

Illin

ois

Bas

in (

102.

7

Bla

ck W

arrio

r Bas

in

;0.0

)

;0.0

)

(61.

5,0.

0)

6315

Pre

cam

bria

n R

ift

6405

Illi

nois

Bas

in -

Rou

gh C

reek

Gra

ben

6501

Cam

bria

n an

d O

rdov

icia

n C

arbo

nate

6502

Upp

er M

issi

ssip

pian

San

dsto

ne65

03 P

enns

ylva

nian

San

dsto

ne65

05 D

evon

ian

Che

rt an

d C

arbo

nate

H H H C C H

0.1 1.0

1.0

1.0

1.0

0.8

1000

0

4500

1000

2500

1500

2000

2000

0

1200

0

1000

080

0070

0080

00

3000

0

1900

0

2500

016

000

1500

018

000

1.0

1.0

0.8

0.8

1.0

1.0

0

102 42 14 0 5.0 .7 .3 .1 .0 .1

Prov

ince

nam

ePl

ay n

umbe

r an

d na

me

Stat

us

Prob

D

epth

(fee

t) G

as

Non

-ass

oc.

________m

in

med

m

ax

frac

tion

gas

volu

me

App

alac

hian

Bas

in (

129.

6; 0

.0)

Blu

e R

idge

Thr

ust B

elt (

0.0;

0.0

)

6701

Rom

e Tr

ough

6702

Upp

er C

ambr

ian,

Ord

ovic

ian,

an

d L

ower

/Mid

dle

Sulu

rian

Thru

st

Bel

t67

03 B

eekm

anto

wn/

Kno

x C

arbo

nate

O

il/G

as67

04 R

ose

Run

/Gat

esbu

rg/T

here

sa S

and­

st

one

Gas

6706

Tre

nton

/Bla

ck R

iver

Car

bona

te O

il an

d G

as

6801

Sou

ther

n A

ppal

achi

ans

Sub-

Thru

st

Shee

t

H

0.8

6000

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2500

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1000

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9000

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8000

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1500

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