Page 278 - Geology and Geochemistry of Oil and Gas

MODELS OF STATIC GEOLOGIC SYSTEMS 241

Fig. 11.16. Dependencies between Palmer’s characteristics and water salinity.

disthene (disthene, staurolite, sillimanite), (4) micas (muscovite, biotite, chlorite),
and (5) glauconite. The distributions (contents) of these mineral groups in rocks are
presented in Fig. 11.17.
The triangular diagrams (see Fig. 11.18) show the rock composition (Productive
Series of the South Caspian Basin) with respect to quartz (Q), feldspar (FS), and
rock fragments (RF). Fig. 11.18 also shows the contour lines of equal concentration
of heavy minerals with respect to the overall mineral composition of host rocks. The
content of stable minerals generally ranges from 1% to 8% (the relative frequency of
this range is 63%). Content less than 1% is observed in 8% of the cases and more
than 8% in 28% of the cases. The content of stable minerals decreases from 10% for
rocks composed mostly of quartz to 4% for lithite. (Lithite is a rock composed of
sand-size rock fragments.) The kyanite group of minerals is absent in 68% of the
rocks studied. Their content is at a maximum in monomineralic quartz sandstones
(3.8%) and a minimum in lithite (0.2%). The relationship of reservoir-rock prop-
erties (clay content, porosity, and permeability) to mineral composition of rocks is
shown in Fig. 11.19. Petrographic and mineralogic multivariable composition and
reservoir-rock properties of terrigenous (siliciclastic) rocks discussed here are pre-
sented in Table 11.9.

11.2.2.3.2. Crude oil. When data on correlation coefficients for all paired relation-
ships or equations (see Table 11.8) are available, one can derive an equation of
multiple regression containing all three independent variables (resins plus asphalt-
enes content R, gasoline content B, and ligroin content L). The equation of multiple
regression is a linear function

g ¼ g þ aR þ bB þ cL (11.62)
o
where g is the density of crude oil, g is the density of crude oil when R ¼ B ¼ L ¼ 0,
o
and a, b, and c are empirical coefficients.