Page 313 - Geology and Geochemistry of Oil and Gas

274 MATHEMATICAL MODELING IN PETROLEUM GEOLOGY

considered to be almost any carbon-containing organic matter. Temperature wise,
instead of a narrow range of high-temperature petroleum is generated in a broad
temperature range starting at ambient temperature. In terms of the energy source, the
concepts shifted from the heat flow to any other energy source in the Earth’s crust,
including the surface energy of finely fragmented rocks and minerals. Instead of
clay–shale deposits alone, the source facies now include a wide range of subaquatic
deposits. In terms of duration, it changed from a narrow ‘‘window’’ or ‘‘phase’’ to a
long and continuous process occurring in the Earth’s crust at a variable speed.
The future is rather optimistic. In the onshore basins with discovered fields, at
least 30–35% of the reserves remain undiscovered due to imperfection of current
exploration and appraisal techniques. These reserves reside in the (1) lithologic traps,
(2) traps with capillary and hydraulic barriers, (3) synclines or over the monoclines,
(4) poor reservoirs, and (5) ‘‘critical state’’ accumulations. The technological ad-
vances will probably increase the estimated reserves further.
Presently, the sedimentary oil and gas basins, shelves, and continental slope areas
are targets of an accelerated exploratory and appraisal efforts. There is not much
hope to discover major hydrocarbon accumulations in the middle of the oceans. The
potential of the continental slopes is also unknown. The potential of the Antarctica
and its shelves are also not studied.
As the extent of our knowledge of a particular region increases, the efficiency
declines, the fraction of large discoveries drops, and the structure of reserves becomes
more complicated. At the same time, the number of (1) small fields, (2) the amount of
their reserves, (3) the number of oilfields with difficult-to-produce oil, and (4) low-
permeability reservoirs increased. The productivity of newly-completed wells became
lower. More remote areas with harsher natural environment are being explored.
Practically all the giant fields in the World are currently under development and
major producing formations are at a stage of declining production. In Russia, for
example, most gas is produced from two giant West Siberia fields (Orenburg and
Vuktyl fields). Plethora of small fields produce very small amount of oil.
Decline in the petroleum production results in the economic, political, and social
complications. The issue of the scientific studies, especially the fundamental ones, is
becoming acute. The fundamental studies, which are the mainstay of energy indus-
try, are unfortunately decreasing. No technical progress can be achieved in the
absence of scientific progress, and the modern society cannot function without the
technical progress.
The current status and avenue of scientific studies is predicated on the extent of
computerization. It covers analytical and measuring equipment, seismic and logging
equipment, and acquisition, storage and processing of information. Broad applica-
tion of Information Technology provides opportunities for integration of diverse
technologies and modeling of the processes and targets. The computers are very
important in the studies of fundamental problems.

N.A. Eremenko and
G.V. Chilingar