FOREWORD
This report was prepared as part of the World Energy
Project of the U.S. Geological Survey. In this project, the world was divided
into 8 regions and 937 geologic provinces, which were then ranked according
to the discovered oil and gas volumes within each (Klett and others,
1997). Then, 76 "priority" provinces (exclusive of the U.S. and chosen
for their high ranking) and 26 "boutique" provinces (exclusive of the U.S.
and chosen for their anticipated petroleum richness or special regional
economic importance) were selected for appraisal of oil and gas resources.
Portions of numerous additional "boutique" provinces were eventually included.
The petroleum geology of these priority and boutique provinces is described
in this series of reports.
The purpose of the World Energy Project is to assess the
quantities of oil, gas, and natural gas liquids that have the potential
to be added to reserves within the next 30 years. These volumes either
reside in undiscovered fields whose sizes exceed the stated minimum-field-size
cutoff value for the assessment unit (variable, but must be at least 1
million barrels of oil equivalent) or occur as reserve growth of fields
already discovered.
The total petroleum system constitutes the basic geologic
unit of the oil and gas assessment. The total petroleum system includes
all genetically related petroleum that occurs in shows and accumulations
(discovered and undiscovered) that (1) has been generated by a pod or by
closely related pods of mature source rock, and (2) exists within a limited
mappable geologic space, together with the essential mappable geologic
elements (reservoir, seal, and overburden rocks) that control the fundamental
processes of generation, expulsion, migration, entrapment, and preservation
of petroleum. The minimum petroleum system is that part of a total petroleum
system encompassing discovered shows and accumulations along with the geologic
space in which the various essential elements have been proved by these
discoveries.
An assessment unit is a mappable part
of a total petroleum system in which discovered and undiscovered fields
constitute a single relatively homogenous population such that the chosen
methodology of resource assessment based on estimation of the number and
sizes of undiscovered fields is applicable. A total petroleum system might
equate to a single assessment unit, or may be subdivided into two or more
assessment units if each assessment unit is sufficiently homogeneous in
terms of geology, exploration considerations, and risk to assess individually.
A graphical depiction of the elements
of the total petroleum system is provided in the form of an event chart
that shows the time of (1) deposition of essential rock units; (2) trap
formation; (3) generation, migration, and accumulation of hydrocarbons;
and (4) preservation of hydrocarbons.
A numeric code identifies each region,
province, total petroleum system, and assessment unit; these codes are
uniform throughout the project and will identify the same item in any of
the publications. The code is as follows:
A numeric code identifies each region, province, total
petroleum system, and assessment unit; these codes are uniform throughout
the project and will identify the same item in any of the publications.
The code is as follows:
|
Example |
| Region, single digit |
3 |
| Province, three digits to the
right of region code |
3162 |
| Total Petroleum System, two digits
to the right of province code |
316205 |
| Assessment unit, two digits to
the right of petroleum system code |
31620504 |
Oil and gas reserves quoted in this report are derived
from the Petroleum Exploration and Production database (Petroconsultants,
1996) and other reports from Petroconsultants, Inc., unless otherwise noted.
Figure(s) in this report that show boundaries of the total
petroleum system(s), assessment units, and pods of active source rocks
were compiled using geographic information system (GIS) software. Political
boundaries and cartographic representations were taken, with permission,
from Environmental Systems Research Institute's ArcWorld 1:3 million digital
coverage (1992), have no political significance, and are displayed for
general reference only. Oil and gas field centerpoints, shown on this(these)
figure(s), are reproduced, with permission, from Petroconsultants, 1996.
REFERENCES
Environmental Systems Research Institute Inc., 1992, ArcWorld 1:3M digital
database: Environmental Systems
Research Institute, Inc. (ESRI), available from ESRI, Redlands, CA, scale:
1:3,000,000.
Klett, T.R., Ahlbrandt, T. A., Schmoker, J.W., and Dolton, G. L., 1997,
Ranking of the world’s oil and gas
provinces by known petroleum volumes: U.S. Geological Survey Open-File
Report 97-463, one CD-ROM.
Petroconsultants, 1996, Petroleum Exploration and Production Database:
Petroconsultants, Inc., P.O. Box 740619,
6600 Sands Point Drive, Houston TX 77274-0619, USA or Petroconsultants,
Inc., P.O. Box 152, 24 Chemin de
la Mairie, 1258 Perly, Geneva, Switzerland.
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