FOREWORD
This report was prepared as part of the World Energy
Project of the U.S. Geological Survey. In the project, the world was divided
into 8 regions and 937 geologic provinces. The provinces have been 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. The petroleum geology of these priority and boutique provinces
is described in this series of reports. A detailed report containing the
assessment results will be available separately, if such results are not
reported herein. The priority South Barents Basin Province ranks 35th
in the world, exclusive of the U.S. Even though a frontier exploratory
basin, it’s ranking would move to 29th if several adjacent fields
that are part of the same major petroleum system are included within this
greater South Barents area. The North Barents Basin is a boutique province.
The purpose of the World Energy Project is to aid in assessing
the quantities of oil, gas, and natural gas liquids that have the potential
to be added to reserves within the next 30 years. These potential resources
reside either 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 they 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 (source, reservoir, seal, and overburden rocks) that
control the fundamental processes of generation, expulsion, migration,
entrapment, and preservation of petroleum. The total petroleum system concept
is modified from Magoon and Dow (1994). The minimum petroleum system
is defined as that part of a total petroleum system encompassing discovered
shows and accumulations together 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. If necessary, a total petroleum system may be subdivided
into two or more assessment units such that each assessment unit is sufficiently
homogeneous in terms of geology, exploration considerations, and risk to
assess individually. Assessment units are considered established
if they contain more than 13 fields, frontier if they contain 1-13
fields, and hypothetical if they contain no fields.
A graphical depiction of the elements of a total
petroleum system is provided in the form of an event chart that
shows (1) the time of deposition of essential rock units; (2) the time
processes, such as trap formation, necessary for the accumulation of hydrocarbons;
(3) the critical moment in the total petroleum system; and (4) the preservation
time, if any.
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 |
The codes for the regions and provinces are listed in
Klett and others, 1997.
Oil and gas reserves quoted in this report are derived
from Petroleum Exploration and Production database (Petroconsultants, 1996)
and other area reports from Petroconsultants, Inc., unless otherwise noted.
Figures in this report that show boundaries of the total
petroleum systems, 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 these
figures, are reproduced, with permission, from Petroconsultants, 1996.
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