Page 287 - Geology and Geochemistry of Oil and Gas

MODELS OF DYNAMIC GEOLOGIC SYSTEMS 249

Fig. 11.23. Relationship among the kinematic viscosity (n), oil density (g), and temperature (after
Buryakovsky and Dzhevanshir, 1992).

Thus, the empirical equations of the relationships among composition, properties
of the crude oil, and temperature may be derived using the experimental data. These
equations are not only of practical value, but also of theoretical interest.
From the practical point of view, extrapolation of graphical or analytical
models beyond the limits of the experimental data is of great interest. For example,
extrapolation of graphs in Fig. 11.23 or using Eq. 11.72 for temperatures above 501C
enables one to predict the viscosity of crude oils of different densities at temperatures
up to 100–1201C (at depths of 5500–6000 m). Rocks at these depths are most likely to
contain gas-condensate fluids due to the low viscosity of fluids at such temperatures.
In the near-surface rocks (with an average annual temperature of +14.51C) crude
3
oil is degraded into an asphalt-like material with a density of 1.0–1.1 g/cm . Such
deposits of bituminous sands are known to occur at outcrops of oil reservoirs in
different parts of the world.

11.3. MODELS OF DYNAMIC GEOLOGIC SYSTEMS

As a rule, geologic systems, with subsequent technologic impact change either in
‘‘geologic’’ or ‘‘technologic’’ time scale. Thus, in order to develop adequate dynamic
models of geologic and technologic processes, it is necessary to introduce time factor.
The time factor is of a special importance for the problems of any forecasting.
Such problems indeed call for the creation and application of the mathe-
matical models. The successful forecast may depend on the historical evaluation of