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Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures (1991)

Chapter: B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf

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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Appendix B

Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf

Committee on Undiscovered Oil and Gas Resources

Board on Earth Sciences and Resources

Commission on Physical Sciences, Mathematics, and Resources

National Research Council

National Academy Press
Washington, D.C.
1990

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

PREFACE

As part of its responsibility for managing the mineral resources of the U.S. coastal waters of the Outer Continental Shelf (OCS) that lie beyond the states' limits, the Minerals Management Service (MMS) of the U.S. Department of the Interior (DOI) leases areas on the OCS for exploration and exploitation of oil and gas resources. Since 1984, however, Congress has declared a moratorium annually on oil and gas exploration, development, and production in the Georges Bank area of the North Atlantic OCS because of environmental concerns. To address these concerns, the MMS asked the National Research Council (NRC) in 1988 to evaluate the adequacy of the data that the MMS uses to assess the environmental impacts of hydrocarbon exploration and production in the Georges Bank basin. This study was assigned to the Board on Environmental Studies and Toxicology. A subordinate issue—the adequacy of the information used by the MMS to assess the hydrocarbon resources potentially available for exploitation in the Georges Bank basin—was addressed by the Board on Earth Sciences and Resources (BESR) and is the subject of this report.

A few months before being asked to participate in the Georges Bank study, BESR had established a committee to study the methodology and data base used by the U.S. Geological Survey (USGS) and the MMS in their joint national assessment of undiscovered oil and gas resources (U.S. Geological Survey and Minerals Management Services, U.S. Department of the Interior. 1989. Estimates of Undiscovered Conventional Oil and Gas Resources in the United States—A Part of the Nation's Energy Endowment). Because of its particular expertise, this group, the Committee on Undiscovered Oil and Gas Resources, was assigned the subtask of evaluating the data base for the estimates of hydrocarbon resources in the Georges Bank basin made by MMS in conjunction

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

with its lease sale activities. A panel of experts drawn from the full committee was appointed to do the review.

The committee accepted the additional task, which was to be carried out simultaneously with its larger study, with the understanding that its report on the Georges Bank basin would include only those considerations that the committee believed it could address without compromising the overlapping issues that were to be examined in the larger study. The Georges Bank report was scheduled for completion before the report on the national assessment, and the committee had not completed its evaluation of the quantitative methodology used in the national assessment when the Georges Bank report was written. Because the MMS uses the same statistical methodology and applies the same economic considerations for its regional resource evaluation as it did for the national assessment, the panel of the full committee that reviewed the Georges Bank data base was unable to address the issue of the quantitative statistical methodology in its report.

Besides reviewing the data base according to the charge to the committee, however, the report also addresses aspects of the MMS's approach to assessing the resource potential of the Georges Bank basin, such as how the MMS used the geological, geophysical, and geochemical data base, the validity of the MMS's extrapolations to areas lacking data, the MMS's practice of basing estimates of critical parameters on single numbers (point estimates) rather than on a range of values, and the adequacy of the MMS's considerations of uncertainty in its assessments. The report also assesses the impact of these practices on the overall estimates of hydrocarbon resources for the Georges Bank.

To examine the information available to the MMS and to evaluate the adequacy of the staff and facilities for making a credible estimate of the hydrocarbon potential of the Georges Bank area, the panel met at the MMS's North Atlantic Region office in Herndon, Virginia, with MMS staff members and supervisors responsible for the Georges Bank resource evaluation. Excellent cooperation and logistical support from Bruce Weetman, the MMS's regional director for the Atlantic Region, and Maher Ibrahim, MMS's regional supervisor for resource evaluation, assured the effectiveness of the meeting, which was conducted as an informal work session.

The geology and geologic history of the North Atlantic continental margin were reviewed, as were the processes by which hydrocarbons are generated, accumulated, and migrated. The panel then reviewed the nature, quality, and extent of the geological, geophysical, and geochemical data bases used in the resource estimation process. Panel members examined in detail representative

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

samples of the data and reviewed the methods used to identify prospects and plays, as well as details of typical prospects within exploration plays. Finally, the panel examined the procedures by which the MMS determined the potential resources of the basin.

This report on the adequacy of the data base used by the MMS to estimate the hydrocarbon potential of the Georges Bank basin and on the credibility of that estimate is based mainly on the panel's meeting with the MMS's North Atlantic Region office staff, but it also draws on information and deliberations relating to the national assessment, because the MMS's methods and procedures have been essentially the same for both activities.

The Committee on Undiscovered Oil and Gas Resources expresses its appreciation to the MMS and its officials, whose cooperation and organized efforts resulted in a productive and informative meeting that led to the observations and evaluations described in this report.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

EXECUTIVE SUMMARY

In response to a request made to the National Research Council by the Minerals Management Service (MMS), a panel of the Committee on Undiscovered Oil and Gas Resources, operating under the Board on Earth Sciences and Resources, has reviewed the adequacy of the data base used by the MMS to assess the potential amount of undiscovered oil and gas present in the Georges Bank portion of the Outer Continental Shelf (OCS). The panel conducted a detailed examination of information available to the MMS and reviewed the adequacy of the data and the manner in which it was used to produce an assessment of the undiscovered hydrocarbon potential of the Georges Bank area.

The panel found several factors that make the estimates of oil and gas resources in the Georges Bank basin unduly conservative. Further, the estimates are presented in a way that tends to mask their uncertainty. This report therefore, recommends steps to improve the data available to the MMS and the methodology used in the analysis of those data.

In the Georges Bank portion of the OCS, the MMS has identified five exploration play types, i.e., potential oil or gas fields that are geologically related and have similar hydrocarbon sources, reservoirs, and traps. The only wells that have been drilled in the entire basin are in one play type in one part of the basin. While those wells —two Continental Offshore Stratigraphic Test (COST) wells and eight unsuccessful industry exploratory wells—have provided a large amount of stratigraphic, geochemical, and geophysical data, those data do not necessarily hold for the other four play types.

The MMS has a vast amount of seismic reflection data ranging in quality from poor to excellent and covering a wide area of the Georges Bank portion of the OCS. Because of budget limitations, however, the number of new additions, especially of reprocessed data, is often less than adequate.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

Because information from wells is lacking for all but one play in the basin, the estimates of undiscovered hydrocarbon resources are based primarily on the identification of structures from the available geophysical information. As in any frontier province lacking established production, the initial efforts to locate hydrocarbon accumulations have been focused on the most obvious structural traps, which results in the less obvious stratigraphic and combination-type traps initially remaining unrecognized. This practice contributes to the geological uncertainty in the MMS evaluation because it overlooks the possible contribution of unidentified structural and stratigraphic trapping to the resource base. In addition, variations in porosity may go undetected, yet they may form stratigraphic traps with as much potential as areas of uniform porosity arched over low-relief structures.

Extrapolations of drilling results to the other plays in the basin should take into account the large degree of uncertainty involved in trying to estimate the resource base in the undrilled portion of the basin. The panel believes that a careful re-examination of the other plays in the basin using appropriate analogs from comparable sedimentary environments, especially those in Canadian waters to the north, could result in substantial modification of MMS estimates of the resource base with very little additional drilling. No attempt was made to quantify this judgment because it was beyond the scope of this study.

Although geochemical analyses based on data from the wells show that strata within the main sub-basin are organically lean, the type of kerogen in the older sedimentary rocks commonly produces gas, while the type of kerogen in the younger Cretaceous strata generally produces oil under appropriate thermal conditions. The hydrocarbon source in the COST G-1 well is reported by the MMS to be predominantly gas-producing, but the source in the COST G-2 well, carbonates and shales, is more oil-prone, with some gas associated with it.

The MMS's practice of assigning a single numerical estimate to the total number of prospects in a play, which includes both identified and unidentified prospects, masks the wide band of uncertainty that should be attached to this quantity. Also, because it is highly unlikely that all the prospects have been identified in any play type in this frontier province, the fact that the MMS's estimate of the total prospects is approximately equal to the number of identified prospects indicates that the MMS has underestimated severely the true number of prospects in the basin.

The lack of success in the one explored area of the Georges Bank basin appears to have led to low estimates of potential resources for the rest of the area. The MMS's assessment leads to an estimated mean of 40 million barrels

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

of economically recoverable oil. If interpreted without taking into consideration the large degree of uncertainty resulting from the lack of testing of four of the five play types, the MMS's estimate implies an expectation of no more than one Class-B-size field of economically recoverable oil in the basin. Even though the basin seems to be primarily gas-prone, significant oil accumulations remain a good possibility based on geochemical analyses of the carbonates.

The weight given to the unsuccessful exploration results in the Baltimore Canyon area was not balanced by consideration of important discoveries in the Canadian areas of the OCS to the north of Georges Bank. This tended to result in underestimation of the resource potential.

Because of MMS's approach to the data, the absence of wells in four of the five play types, and the paucity of the latest new and reprocessed seismic data, it is the judgment of the panel that the MMS's assessment of undiscovered resources for the entire basin is very conservative.

Recommendations from the panel are in two categories: (1) the need for more data to support credible estimates and (2) steps to ensure careful reconsideration of the resource estimation.

To enhance the data base and to reduce uncertainty in the estimates of oil and gas resources in the Georges Bank basin, the panel recommends the following:

  1. Drilling into each of the identified plays, for the purpose of obtaining geochemical and stratigraphic information for each play;

  2. Increasing the MMS's staff access to reprocessed and more recent seismic data for all parts of the basin;

  3. Upgrading to industry-standard, state-of-the-art data-processing equipment and techniques by the MMS for play and prospect evaluations.

For reconsideration of the resource estimate of the Georges Bank, the MMS should do the following:

  1. Conduct a careful study of the Canadian basin discoveries and, using play summary maps, attempt to identify any favorable trends that can be projected into the U.S. portion of the Georges Bank.

  2. Obtain reprocessed seismic data for portions of the reef trend to evaluate more fully the reservoir characteristics of these strata.

  3. Provide a range of numbers of prospects in each play type to reflect more closely the uncertainty in the actual number of prospects that may exist.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
  1. Report unrisked assessment volumes along with the risk factors.

  2. Reevaluate the lower limit for the range of acreage assigned to each prospect.

The Committee on Undiscovered Oil and Gas Resources concurred with the panel's findings and in its forthcoming report will elaborate further on the MMS's resource estimation methodologies and procedures, which, in the committee's judgment, tend to produce overly conservative estimates of undiscovered oil and gas resources.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

1

INTRODUCTION

In 1988, the Minerals Management Service (MMS) requested the National Research Council (NRC) to undertake an examination of MMS hydrocarbon resource estimates of the Georges Bank area of the North Atlantic Outer Continental Shelf (OCS). This study was assigned to the Board on Mineral and Energy Resources (BMER) [now the Board on Earth Sciences and Resources (BESR)]. At the time of this request, the board had already initiated an examination of the methodologies and procedures used by the MMS and the U.S. Geological Survey (USGS) in their most recent joint national assessment of undiscovered conventional oil and gas resources of the United States (U.S. Department of the Interior, 1989). The Committee on Undiscovered Oil and Gas Resources that had been established to conduct the larger review of MMS and USGS methodologies and procedures was assigned the examination of the Georges Bank resource assessment.

The specific charge to the committee with respect to the Georges Bank area was as follows:

Assessments will be conducted of the adequacy of the scientific and technical information to evaluate the estimates of the hydrocarbon resource base of the designated moratorium area of the North Atlantic OCS. The assessments will include an examination of

  • what is known, plus reasonable extrapolations, accompanied by an expression of the error or uncertainty;

  • what is not known, and the reasons why (e.g., difficulty of measurement, confounding of data, lack of theory, lack of data, insufficient time); and

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
  • what could be known with various reasonable additional investigative resources (manpower, money, facilities) and time.

The above assessments will be made in the context of the MMS's need to support leasing decisions and to predict and manage environmental effects of OCS oil and gas activities.

The committee set up a panel on Georges Bank from among its members to address this task. A related study of environmental impacts was done simultaneously by the NRC's Board on Environmental Studies and Toxicology (BEST).

The panel met with the MMS staff at their office in Herndon, Virginia, where the data used for the Georges Bank estimate and for the entire U.S. North Atlantic OCS are maintained. The geology of the Georges Bank was reviewed, and the geological and geophysical data used in the resource estimation process were examined to evaluate the nature, quality, and extent of the data base. The geochemical characteristics of the basin were reviewed, and information related to the gas- or oil-prone nature of the sedimentary strata was examined. The methods used in identifying prospects 1 and establishing exploration plays 2 were examined and typical prospects within exploration plays were reviewed.

After reviewing information relating to the factors that cause hydrocarbon accumulations, the panel examined the procedures by which the potential resources of the basin were determined and made a judgment as to the adequacy of the assessment of undiscovered oil and gas resources assigned by the MMS to the Georges Bank basin.

Although the committee concurred with the panel's findings, as presented herein they are to be considered preliminary and are subject to review and possible modification by the committee in its forthcoming report on the joint national assessment conducted by the MMS and USGS.

1  

Prospect — A potential oil or gas field.

2  

play - A group of geologically related prospects with similar hydrocarbon sources, reservoirs and traps.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
Location

Georges Bank is the most southwestern of a series of banks on the North Atlantic Outer Continental Shelf (OCS) that parallel the coast between Newfoundland and Nantucket Island (Fig. 1). It is located in a region of numerous deep submarine canyons, but the bank has a moderate water depth commonly less than 260 feet. The Georges Bank is a trough-shaped, extensional basin, about 200 miles long by 80 miles wide. On average it contains in excess of 26,000 feet in thickness of Mesozoic and Cenozoic sedimentary strata, with several deeper sub-basins containing as much as 40,000 feet in thickness of sedimentary rocks.

A dispute regarding the boundary between the Canadian and U.S. portions of the basin was resolved by the International Court of Justice in a ruling that defined the location of the boundary. The approximate location of that boundary is shown in Figure 1.

The Georges Bank basin is the northernmost of seven geologically defined provinces constituting the MMS subdivisions of the Atlantic OCS (Region 9-A). It is also the northernmost of the four MMS planning areas of the Atlantic OCS for lease sale and regulatory purposes.

Geologic History

The Georges Bank area provides evidence for a generally accepted geologic history that includes the entire North Atlantic region. Older sedimentary strata, accumulated prior to the rifting and separation of a large continental mass into the present-day continents, lie below younger marine and terrigenous deposits formed in the Triassic and Jurassic Periods during and after continental rifting. The rock types seem to have been controlled mainly by ancient seafloor topography and the distance from ancient shorelines. The sedimentary rocks deposited before and during the rifting stages are now preserved in rift grabens and half-grabens; they are the reworked products of the erosion of a thick section of Paleozoic and Triassic clastic, volcaniclastic, and fresh water deposits. These grabens formed in the crystalline and metasedimentary basement rocks.

The graben-filling deposits were further faulted and deformed during the long rifting process. During the Triassic, as rifting began, the region was uplifted and then reduced to an erosional plane, forming an unconformity (the breakup unconformity) above which Triassic coastal sedimentary rocks were deposited.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

FIGURE 1 Index map of the Georges Bank area showing location of COST and exploratory wells (rectangular grid), and location of cross section (A-A′) shown in Figure 2. SOURCE: Minerals Management Service, Atlantic Region.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

Distinctive episodes of rifting continued into Jurassic time. After the initial rifting, marine waters inundated the area during Late Triassic time, depositing shallow marine and shoreline sediments. These included limestones, dolomites, and evaporites (mostly salt).

Shoreward, this sequence contains clastic rocks and coal beds. Seaward, large thicknesses of evaporites were deposited. The evaporites were subsequently deformed by sediment loading and produced a number of salt diapirs in the northeastern part of the area. A widespread erosional unconformity caps the Triassic coastal, shallow marine sequences.

An Early Jurassic rifting episode renewed subsidence, resulting in the widespread deposition of a sandstone that was subsequently subaerially exposed. Rift-related tectonics ended by Middle Jurassic time, when Atlantic basin subsidence and changes in sea level caused more open marine conditions and the consequent deposition of limestones (some of which were later altered to dolomite). The lowering of sea level, shortly after the beginning of the Late Jurassic, produced a pronounced eastward (seaward) shift in the limit of clastic sedimentation. Except for periodic fluctuations of relatively short duration, sea level has remained near its present position since Late Jurassic time. Therefore, Cretaceous and Tertiary sedimentary strata are nearly all sandstones, shales, and siltstones with some thin, interbedded limestones.

A pronounced shelf edge was established by the middle of Late Jurassic time as the ocean basin continued to subside (Fig. 2). Carbonate detritus, consisting of shells, coral fragments, and other biogenic products, accumulated along the outer shelf edge, forming a carbonate reef that is distributed discontinuously and is parallel with the present shelf break. Carbonate accumulation persisted into the Early Cretaceous, when it was terminated, probably because of climate and sea-level changes.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

FIGURE 2 Cross Section A-A′ showing stratigraphic section in the two COST wells and across the Georges Bank basin interpreted from seismic profile. Location given in Figure 1. V symbols at base of sedimentary strata indicate acoustical basement. SOURCE: Modified from Poag, C, W., 1982.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

2

GEOLOGICAL AND GEOPHYSICAL DATA BASE

During the period 1966 to 1988, 111,000 line miles of Common Depth Point (CDP) seismic data were collected in industry-supported offshore seismic surveys in the Georges Bank (Fig. 3). Of this total, the MMS North Atlantic regional office has in its possession data on approximately 62,000 line miles in the U.S. portion of Georges Bank and 6,000 line miles in the Canadian portion. In addition, the MMS also has a substantial quantity of time-migrated seismic data, depth-migrated seismic data, relative-amplitude data, velocity scans, and gravity and magnetic data.

The seismic grid, ranging from 1/8 mile by 1/8 mile in the lease sale areas to 3 miles by 3 miles outside, as well as other geophysical parameters, were chosen by the industry using standard, state-of-the-art geophysical practice adequate for locating potential oil-bearing structures. The seismic grid for the Georges Bank basin is spaced sufficiently to identify significant structures that may contain hydrocarbons, but the processing of some lines may not be adequate to identify all of the existing structures in a particular play.

As in any large geophysical survey, the quality of data characterizing the Georges Bank basin ranges from fair to very good, with the poorest-quality data having been acquired before 1975. Also, as would be expected, the conventional CDP data obtained over the deep-water canyon areas are of poorer quality. However, to correct this inadequacy, the MMS obtained specially processed data (by wave-equation depth migration) from the Exxon Corporation to gain a better picture of the structures in the deep-water canyon areas.

The MMS systematically updates its geophysical data base with new data, as well as reprocessed data, as soon as they become available. Because of budget limitations, however, the number of new additions, especially of reprocessed

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

FIGURE 3 Index map of the Georges Bank basin area showing lines of seismic profiles available to the Minerals Management Service. High concentration of seismic lines in vicinity of 41°N latitude/68°W longitude is location of two COST wells and several industry exploratory wells. SOURCE: Minerals Management Service, Atlantic Region.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

data, is often less than adequate. The highly qualified geophysical staff of the MMS has been able to analyze and interpret this massive collection of geophysical data using industry-accepted methods and standard techniques despite their small number.

The seismic data were integrated with the available geologic data taken from a small number of wells in an effort to relate seismic reflection events to specific geologic horizons. Only ten wells have been drilled in a limited area of the basin (see Fig. 1). The first two were the Continental Offshore Stratigraphic Test (COST) G-1 and G-2 wells, which were drilled by a consortium of companies to establish the geological, geophysical, and geochemical characteristics of the basin. The objective of both COST wells was to provide as much stratigraphic information as possible about the basin—not to discover oil or gas. (As a matter of MMS policy, COST wells are located away from structures to avoid potential accumulations of hydrocarbons.) Subsequently, eight exploratory wildcat wells were drilled by Exxon, Conoco, Tenneco, Mobil, and Shell; all eight proved to be dry holes, except for some shows of wet gas.

The MMS obtained all pertinent information on the COST wells. These data include engineering and operations reports, well logs, well surveys, seismic check-shot surveys, core descriptions, core photographs, petrophysical analyses of core plugs, washed and dried cutting samples, and canned samples for geochemical analyses. In addition, a full range of information was available to the MMS on a number of industry wells that were drilled after the COST wells and were subjected to similar geoscientific evaluation. MMS geoscientists conducted lithological and petrographic analyses, paleontologic and depositional environmental studies, log analyses and formation evaluations, and optical kerogen and molecular geochemical analyses on the available well data. From the data, they produced play and prospect maps.

The two COST wells (G-1 and G-2) served as keys for determining for that play (1) the nature of the stratigraphic sections (lithofacies, reservoir facies, and so on) penetrated in this area, (2) the levels of geothermal (time-temperature) diagenesis of the sedimentary strata throughout geologic time, (3) the nature of the resident organic matter characterizing each of the differing lithofacies, and (4) the organic carbon content and hydrocarbon richness of the various strata encountered. These data provided the foundation of a geochemical-geological framework for this area. Complementary (although not as complete) geochemical information was available to the MMS from the eight subsequently drilled industry wells. In addition, the MMS has acquired geochemical data from surveys and bottom samples aimed at direct detection of hydrocarbons.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

The MMS makes some of the data available to the public by including information from each COST well in published OCS reports. In addition to these reports, the MMS has published a report on one of the industry-drilled wells, the Exxon Lydonia Canyon 133-1 well.

All of the Georges Bank industry and COST wells are clustered in the main sub-basin of the province, representing investigation of about 5 percent of the basin area and about 3 percent of the volume of sedimentary strata in the basin (see Fig. 1 ). Most of the basin is devoid of well drilling and the data such drilling provides. While this situation is not unusual in the exploration of new oil and gas provinces, the absence of wells in a large part of the basin requires that most of the judgments pertaining to the resource potential and decisions concerning the potential of undrilled prospects outside the sub-basin be based solely on geophysical data and comparison with analogous geological areas that have been more extensively drilled.

Although the MMS has done a professionally competent job in interpreting the available geophysical data, it must be noted that the use of geophysical data alone for estimating oil and gas resources has limitations. Any procedure that relies solely on such information is beset by uncertainties that affect estimates of the undiscovered oil and gas resources estimates of the area.

In comparing analogous geological areas, the MMS relied primarily on the disappointing exploration experience in the Baltimore Canyon area to the south of the Georges Bank basin. No consideration was given to the more successful exploration results in the Canadian basins to the north.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

3

PETROLEUM GEOLOGY

The MMS has identified five general exploration play types 3 in the Georges Bank basin: (1) Triassic rift basins filled with Triassic and Lower Jurassic sedimentary strata, (2) anticlines on the continental shelf (Jurassic and Lower Cretaceous strata), (3) shelf edge, carbonate reef trend with discontinuous areas of enhanced porosity in Upper Jurassic and Lower Cretaceous rocks, (4) Upper Jurassic and Lower Cretaceous sedimentary wedgeouts against the slope and seaward edge of the reef trend, and (5) structural traps seaward of the continental shelf in Upper Jurassic and Lower Cretaceous strata. The Triassic rift-basin play has been subdivided into three categories of trap types: (a) structures within the Triassic rift basins, (b) stratigraphic traps in Triassic rift basins, and (c) stratigraphic traps in rift basins formed by only one fault downthrown in the landward direction (half-grabens). Part of the rift-basin play underlies the continental shelf anticline play.

The ten wells (two COST wells and eight industry wells), localized in a small area, evaluated a single play type—Jurassic anticlines on the continental shelf. The COST wells tested two of the sedimentary sections of interest in this area, an inner neritic-type clastic sequence penetrated by the COST G-1 well, and a thick shelf and reef carbonate sequence penetrated by the COST G-2 well. However, both of these classes of sedimentary strata relate only to the shelf anticline play. The wildcat wells, as mentioned previously, were unsuccessful, containing only shows of wet gas.

Seismic data, confirmed by well information in the limited area where well control is available, indicate that the anticlinal structures tend to be less

3  

Play type — The specific geologic structure or rock type that characterizes a play.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

pronounced at shallow depths. In part, sediments draped over basement uplifts have blanketed and modified the well-developed deeper structures.

It should be emphasized that, in areas where structures are not large or well developed, local variations in porosity both areally and at depth may form stratigraphic traps with as much potential as areas of uniform porosity arched over low-relief structures. The relative timing of the formation of traps, predating the generation and migration of hydrocarbons from the source rocks to the traps, allows for possible accumulations. In addition, the occurrence of shales and anhydrites interbedded with potential reservoir rocks such as sandstone and carbonate seems to be adequate to seal any trapped accumulations.

While the MMS has mapped three seismic horizons in the Georges Bank basin, only one of the mapped horizons (approximately Middle Jurassic) has been used, and then only as an average structural indicator in the resource assessment. Each play has been defined on a summary sheet that includes the play description and parameters that characterize the play, such as porosity, thickness, acreage, and so on. In addition, a trap file is maintained for individually identified prospects to document the essential elements of each. Analogs of fields producing from similar traps have also been identified to establish a possible order of magnitude of oil and gas accumulation that might be expected if the prospect were found to be productive.

The MMS has defined the geological parameters that could produce hydrocarbon accumulations in this frontier province. As with any frontier province lacking established production, the initial efforts to locate hydrocarbon accumulations have been focused on the most obvious structural traps, which has resulted in the less obvious stratigraphic and combination-type traps initially remaining unrecognized. It is commonly accepted that once commercial production is established within a basin, a deliberate and aggressive search for additional traps, spurred by economic incentive, should produce a significantly larger number of prospects.

Geochemical analyses of samples from the COST G-1 and G-2 wells and from available industry wells indicate that the sedimentary strata within the main sub-basin of Georges Bank, where all the wells are situated, tend to be organically lean. Organic content is higher in shallow horizons (0.7 to 1.0% total organic content [TOC]) and is more dispersed with depth. Cretaceous strata seem to be more oil-prone, whereas the older sedimentary rocks contain kerogen types that, at maturation, commonly produce gas. Geothermal gradients indicate that oil should be generated above 12,000 feet and gas generated below that level.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

The hydrocarbon source for the sandstones in the COST G-1 well, Jurassic and Cretaceous shales, is reported by the MMS to be predominantly gas-prone, and most of the analyzed samples show the organic content to be immature and lean. Rocks that occur in the middle zone (Zone B) in the well are immature but have the potential to be good sources for oil and associated gas if found in areas of higher thermal maturity (G. Bayliss, personal communication). In contrast, the source for the carbonate strata in the COST G-2 well, Jurassic carbonates and intercalated shales containing amorphous-sapropellic kerogen, is more oil-prone, with associated gas, especially in the lower part of the section. The organic content of the strata in Zone D (13,700 to 16,900 feet) are rated as fair to good sources of oil and associated gas at initial stages of petroleum liquid generation. The organic content of the carbonate sections in this well indicates that such strata will be of major significance to the hydrocarbon potential of the basin (G. Bayliss, personal communication). Moreover, these considerations with different types of organics at different stratigraphic levels, indicate more than one source for the hydrocarbons in a single play.

In assessing the hydrocarbon potential of carbonate-related oil plays, the importance of the dominant amorphous-sapropellic kerogen (oil-prone) facies in estimating hydrocarbon potential transcends both the low TOC content and the regionally lower thermal maturity characteristic of the area, because this type of kerogen begins producing oil liquids at lower levels of thermal maturity than all other types (Bayliss, 1985, Fig. 2). Thus the limestones of the explored part of the Georges Bank with low organic carbon contents that are only moderately thermally mature can be very prolific sources for oil liquids because of their ideal oil-prone amorphous-sapropellic kerogen content. This situation suggests a greater potential for oil accumulations in the Jurassic anticline play than the MMS expects.

Although the available geochemical data enable a reasonable assessment of the oil- and gas-generating potential of one sub-basin in the Georges Bank area, extrapolating this information to estimate such potential throughout the basin involves a substantial degree of uncertainty because of the absence of a complete network of wells. This deficiency is particularly relevant to the resource assessment, because prospects seaward of the reef edge are likely to exhibit an organic content much higher than that observed on the shelf and should become more sapropellic. The oil- and gas-generating potential seaward of the reef edge, and consequently the probable hydrocarbon resources, should be greater than the resources on the shelf because of the presence of more favorable organic source material (Bayliss, 1985, Fig. 2 and Fig. 3).

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

As previously mentioned, the two COST wells tested only two of the sedimentary sections of interest in this area—a thick, inner neritic-type clastic sequence (G-1 well), and a thick shelf and reef carbonate sequence (G-2 well). Reservoir-quality rocks are commonly present in the sandstones, whereas the development of porosity in the carbonate strata is more variable and facies-dependent. A trend of carbonate porosity is present along the reef, where it provides one of the trap types recognized by the MMS. In general, depending on the sequence of rocks encountered in a well, porosity tends to be greater at the shallower depths. As the source rocks associated with the carbonates of the area are more oil-prone than are the deeper clastic rocks, the carbonate reef trend should have a greater potential for liquids than for gas.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

4

PETROLEUM RESOURCE ASSESSMENT OF THE GEORGES BANK

The MMS's summary of the undiscovered resource assessment of the Georges Bank basin is shown in Table 1.

TABLE 1. Probability Estimates of Undiscovered Oil and Gas in Georges Bank Basin (expressed in terms of volume versus percent chance).

 

Crude Oil (billion bls) *

Natural Gas (tcf) **

 

95%

Mean

5%

95%

Mean

5%

Technically recoverable

0.00

0.10

0.38

0.00

1.94

6.75

Economically recoverable

0.00

0.04

0.19

0.00

0.98

4.16

* Barrels

** Trillion cubic feet

† Reported as 0.00 because the probability of no technically (economically) recoverable oil (gas) is greater than 0.05.

SOURCE: U.S. Geological Survey and the Minerals Management Service,1989.

Approximately 79 percent of the risked 4 , economically recoverable resources reported by the MMS are assigned to two play types: anticlines on the continental shelf and structures within Triassic rift basins. The former play type

4  

Risk is the probability that no commercial oil or gas field exists.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

is assigned about 48 percent and the latter play type about 31 percent of the total hydrocarbon resources of the basin. Accessibility is one factor in assigning a large proportion of the resource to these two plays types because they are superimposed and are located on the continental shelf where the relatively shallow water makes drilling easier and less expensive. Both of these play types are logical and primary targets in the early phases of exploration, but if they alone are emphasized, as the MMS has done, the possibility of large oil and gas accumulations in other play types—such as the shelf-edge carbonate reef trend, seaward sedimentary wedgeouts against the slope and seaward edge of the reef trend, and structural traps seaward of the continental shelf—may not be given proper consideration. Only 21 percent of the hydrocarbon resources in the Georges Bank basin are expected to come from the five other play types, even though prospects within these plays include carbonate facies that geochemical analysis indicates are more oil-prone than the sandstone facies.

As reported in the MMS's summary table (Table 1), a mean of only 40 million barrels of economically recoverable oil is estimated for the Georges Bank basin. This represents the equivalent produced by just one Class-B-size field. If interpreted without taking into consideration the very large degree of uncertainty that exists because of the lack of testing of four of the five play types and the limited testing in only one part of the basin of the other play type, the MMS's estimate implies an expectation of no more than one Class B economic oil field in the basin. Estimates of recoverable gas are slightly higher; 0.98 trillion cubic feet (tcf) of economically recoverable gas (Table 1) equals the output of about one national-class, giant gas field. Estimates such as those shown in Table 1 that do not reflect the large degree of uncertainty brought about by lack of data in the basins being evaluated lead to very conservative numbers, in the panel's judgment.

Data obtained from only the two COST wells and eight unsuccessful industry exploratory wells in one play, localized in the same sub-basin, should not have been extrapolated to characterize the average amount of economically recoverable undiscovered hydrocarbons in the entire basin, because the other plays are fundamentally different and must have independent hydrocarbon sources based on their structural and geographic locations.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

The MMS assigns a numerical estimate for the number of prospects in each play type for input into the PRESTO 5 model. In several plays, the total number of prospects within the play was set equal to the number of identified prospects; that is, it was assumed that there are no unidentified prospects. In other cases, a range of numbers was entered when MMS geologists assumed that not all of the prospects in a play have been mapped. The assignment of a single number for the prospects in each play type, for whatever reason, does not show an adequate appreciation of the uncertainty in the current state of knowledge in this area.

It is highly unlikely that all the prospects have been identified in any play type in this frontier province. The seismic data and the fact that knowledge of the basin is very incomplete suggest that many unidentified prospects remain. Therefore a single numerical estimate of the total number of prospects in a play that is close to the number of identified prospects almost always underestimates the true number of prospects in the basin. In addition, the single value masks the wide band of uncertainty that should be attached to this quantity. Explicit representation of the current state of uncertainty about the number of prospects in the Georges Bank basin would indicate a degree of uncertainty about recoverable resources that is larger than that presented by the MMS.

The panel considers the range of acreage assigned to prospects to be too wide. For example, the acreage assigned for the shelf anticline play ranges from 6 to 36,780 acres for 90 prospects; the area assigned for the anticline play seaward of the reef trend ranges from 18 to 12,590 acres; the Triassic rift basin play is assigned a range from 2 to 16,583 acres. The lower limit of these ranges is so low as to be unreasonable.

The exploration history of the Baltimore Canyon about 500 km to the southwest of Georges Bank, which has produced poor results, appears to have played a major role in the MMS's resource evaluation of Georges Bank. In contrast, no consideration was given to the more successful exploration programs in the geologically similar Canadian areas to the north. The appropriate weight that should be given to these related areas can be determined by the use of play summary maps of the source reservoir and trap conditions in the Canadian sector to see if any favorable trends can be projected into the U.S. part of the area. Balanced consideration of the exploration history of geologically similar

5  

The acronym for Probabilistic Resource Estimates Offshore, a computer model developed by the MMS for the assessment of undiscovered hydrocarbons using a simulated exploration methodology.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

contiguous areas would yield more realistic expectations than those of the current estimate.

In summary, the combined effects of several practices in the MMS's approach to resource estimation result in very conservative estimates of the potential oil and gas resources in the Georges Bank basin of the North Atlantic OCS.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

5

CONCLUSIONS

The Georges Bank basin contains five identified play types, only one of which has been tested through drilling. That play is located in one small area of the basin. Most of the basin remains unexplored.

Although the seismic grid is adequate to identify significant structures present in the basin, the small amount of reprocessed seismic data the MMS is able to obtain limits the staff's ability to evaluate fully the potential hydrocarbon accumulations in some of the plays, especially those related to stratigraphic traps and to carbonate rocks that are in deeper water.

The estimates produced by the MMS for oil and gas resources in the Georges Bank basin are judged by the panel to be overly conservative because of the following MMS practices in its resource assessments:

  1. Using single-number estimates instead of ranges of key quantities;

  2. Assuming that the total number of prospects in a play is equal to the number of identified prospects;

  3. Using only unsuccessful exploration results in analogous areas such as the Baltimore Canyon;

  4. Extrapolating from areas of low potential, such as shelf anticline plays, to more promising areas, such as the carbonate reef or the area seaward of the reef, which have more favorable organic source material;

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
  1. Ignoring the potential of stratigraphic traps in favor of the more obvious structural traps; and

  2. Inadequately incorporating expressions of uncertainty in the estimation process, a necessary step given the lack of drill information for four of the five play types in the basin.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

6

RECOMMENDATIONS

Recommendations fall into two categories: (1) the need for more data to support credible estimates and (2) steps to ensure careful reconsideration of the resource estimation.

Data Needs

With additional investigative resources, much needed information essential to a credible estimate of the hydrocarbon resources could be obtained that would reduce the uncertainty and lead to more realistic estimates. Such investigative resources include:

  1. Drilling into each of the identified plays, for the purpose of obtaining geochemical and stratigraphic information for each play;

  2. Increasing the MMS's staff access to reprocessed and more recent seismic data for all parts of the basin;

  3. Upgrading to industry-standard, state-of-the-art data-processing equipment and techniques by the MMS for play and prospect evaluations.

Reconsideration of the Resource Evaluation

Much of the foregoing discussion suggests that to ensure a thorough reconsideration of its evaluation of the resource potential of the Georges Bank

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

basin, the MMS should do the following:

  1. Conduct a careful assessment of information from the exploration and related resource assessment activities for the Canadian basins to the north of Georges Bank. With that information, play summary maps should be constructed of the source, reservoir, and trap conditions of the Canadian discoveries to see if any favorable trends can be projected to the U.S. portion of the area. This would enhance greatly the MMS's ability to assess more effectively the undrilled portions of Georges Bank.

  2. Obtain reprocessed seismic data for portions of the carbonate reef trend to evaluate more fully the reservoir characteristics of these strata.

  3. Provide a range of numbers of prospects in each play type for input to the PRESTO model to reflect more accurately the uncertainty in the actual number of prospects that may exist in each play type.

  4. Report unrisked estimated volumes of oil or gas in the prospects along with the risk factors.

  5. Reevaluate the lower limit for the range of acreage assigned to each prospect.

A full discussion of the methodologies and procedures by which resource estimates made by the MMS tend to be systematically conservative is beyond the scope of this review of the data base, but will be addressed by the full committee in its report scheduled to be released in late 1990.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×

REFERENCES

Amato, Roger V. and Bebout, John W., eds. 1980. Geologic and Operational Summary, COST No. G-1 Well. Georges Bank Area, North Atlantic OCS. U.S. Geological Survey. Open-File Report 80-268.

Amato, Roger V. and Simonis, Edvardas K., eds. 1980. Geologic and Operational Summary, COST No. G-2 Well. Georges Bank Area, North Atlantic OCS. U.S. Geological Survey. Open-File Report 80-269.

Bayliss, G. 1985. Geochemistry in Oil and Gas Exploration: A Review. World Oil, August 1.

Poag, C. W. 1982. Stratigraphic Reference Section for Georges Bank Basin: Depositional Model for New England Passive Margin. Bulletin, American Association of Petroleum Geologists, vol. 66. no. 8, pp. 1020-1041.

Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
Page 132
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
Page 135
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
Page 136
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
Page 137
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 139
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 140
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 141
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 142
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 143
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 144
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 145
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 146
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 147
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 148
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 149
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
×
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 155
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 156
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 157
Suggested Citation:"B Adequacy of the Data Base for Hydrocarbon Estimates of the Georges Bank Area of the North Atlantic Outer Continental Shelf." National Research Council. 1991. Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures. Washington, DC: The National Academies Press. doi: 10.17226/1789.
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Page 158
Next: C The Effects of Play Mixing in the Permian Basin »
Undiscovered Oil and Gas Resources: An Evaluation of the Department of the Interior's 1989 Assessment Procedures Get This Book
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When the U.S. Department of the Interior released its 1989 estimates of how much undiscovered oil and gas remain in the United States, a controversy ensued. Some members of the petroleum industry charged that the estimates were too low. This book evaluates the scientific credibility of the statistical and geological methods underlying the estimates.

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