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During the last 30 years, the methodology for assessment of undiscovered conventional oil and gas resources used by the Geological
Survey has undergone considerable change. This evolution has been based on five major principles. First, the U.S. Geological
Survey has responsibility for a wide range of U.S. and world assessments and requires a robust methodology suitable for immaturely
explored as well as maturely explored areas. Second, the assessments should be based on as comprehensive a set of geological
and exploration history data as possible. Third, the perils of methods that solely use statistical methods without geological
analysis are recognized. Fourth, the methodology and course of the assessment should be documented as transparently as possible,
within the limits imposed by the inevitable use of subjective judgement. Fifth, the multiple uses of the assessments require
a continuing effort to provide the documentation in such ways as to increase utility to the many types of users.
Undiscovered conventional oil and gas resources are those recoverable volumes in undiscovered, discrete, conventional structural
or stratigraphic traps. The USGS 2000 methodology for these resources is based on a framework of assessing numbers and sizes
of undiscovered oil and gas accumulations and the associated risks. The input is standardized on a form termed the Seventh
Approximation Data Form for Conventional Assessment Units. Volumes of resource are then calculated using a Monte Carlo program
named Emc2, but an alternative analytic (non-Monte Carlo) program named ASSESS also can be used.
The resource assessment methodology continues to change. Accumulation-size distributions are being examined to determine how
sensitive the results are to size-distribution assumptions. The resource assessment output is changing to provide better applicability
for economic analysis. The separate methodology for assessing continuous (unconventional) resources also has been evolving.
Further studies of the relationship between geologic models of conventional and continuous resources will likely impact the
respective resource assessment methodologies. 相似文献
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A. Schäfer T. Utescher M. Klett M. Valdivia-Manchego 《International Journal of Earth Sciences》2005,94(4):621-639
In the Cenozoic, the Lower Rhine Basin formed as a rift at the southeastern terminus of the Dutch German Central Graben, while the Rhenish Massif was uplifted. The study focusses on the marginal marine and fluvial fill of the Lower Rhine Basin. A basin model is developed. Support for this study was given by extensive industry outcrop and well data, by new stratigraphical and sedimentological observations. The ingression and subsequent regression of the Cenozoic North Sea is analysed using the concept of base level cyclicity. As the geohistory of the basin was complex, a subsidence curve is constructed. Furthermore, an attempt is made to trace the simultaneous uplift of the Rhenish Massif. 相似文献
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Comparison of Methods Used to Estimate Conventional Undiscovered Petroleum Resources: World Examples
Various methods for assessing undiscovered oil, natural gas, and natural gas liquid resources were compared in support of
the USGS World Petroleum Assessment 2000. Discovery process, linear fractal, parabolic fractal, engineering estimates, PETRIMES,
Delphi, and the USGS 2000 methods were compared. Three comparisons of these methods were made in: (1) the Neuquen Basin province,
Argentina (different assessors, same input data); (2) provinces in North Africa, Oman, and Yemen (same assessors, different
methods); and (3) the Arabian Peninsula, Arabian (Persian) Gulf, and North Sea (different assessors, different methods). A
fourth comparison (same assessors, same assessment methods but different geologic models), between results from structural
and stratigraphic assessment units in the North Sea used only the USGS 2000 method, and hence compared the type of assessment
unit rather than the method. In comparing methods, differences arise from inherent differences in assumptions regarding: (1)
the underlying distribution of the parent field population (all fields, discovered and undiscovered), (2) the population of
fields being estimated; that is, the entire parent distribution or the undiscovered resource distribution, (3) inclusion or
exclusion of large outlier fields; (4) inclusion or exclusion of field (reserve) growth, (5) deterministic or probabilistic
models, (6) data requirements, and (7) scale and time frame of the assessment. Discovery process, Delphi subjective consensus,
and the USGS 2000 method yield comparable results because similar procedures are employed. In mature areas such as the Neuquen
Basin province in Argentina, the linear and parabolic fractal and engineering methods were conservative compared to the other
five methods and relative to new reserve additions there since 1995. The PETRIMES method gave the most optimistic estimates
in the Neuquen Basin. In less mature areas, the linear fractal method yielded larger estimates relative to other methods.
A geologically based model, such as one using the total petroleum system approach, is preferred in that it combines the elements
of petroleum source, reservoir, trap and seal with the tectono-stratigraphic history of basin evolution with petroleum resource
potential. Care must be taken to demonstrate that homogeneous populations in terms of geology, geologic risk, exploration,
and discovery processes are used in the assessment process.
The USGS 2000 method (7th Approximation Model, EMC computational program) is robust; that is, it can be used in both mature
and immature areas, and provides comparable results when using different geologic models (e.g. stratigraphic or structural)
with differing amounts of subdivisions, assessment units, within the total petroleum system. 相似文献
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