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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
eight 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. The Timan-Pechora Basin
Province ranks 22nd in the world, exclusive of the U.S.
The purpose of this effort 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 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 occurring in shows and accumulations
(discovered and undiscovered) that has been generated by a pod or by closely
related pods of mature source rock and that 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 minimum petroleum system
is 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.
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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 the a total petroleum system
is provided in the form of an events chart that shows the time of deposition
of essential rock units; the time in which processes (such as trap formation)
necessary to the accumulation of hydrocarbons took place; the critical
moment in the total petroleum system; and 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:
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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 theright 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 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.
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