Page 103 - Geology and Geochemistry of Oil and Gas

76 WATER

TABLE 4.1
Comparison of Three Different Classifications of Water based on Ionic Content (in: Eremenko and
Chilingar, 1996)
After V. A. Sulin After O. A. Aleksin After M. G. Valyashko

Bicarbonate-sodium rHCO 3 4(rCa 2+ +rMg 2+ ) Carbonate
2

Sulfate-sodium rHCO 3 4(rCa 2+ +rMg 2+ )o(rHCO 3 +rSO 4 ) Sulfate type, sodium subtype
2

Chloride-magnesium (rHCO 3 +rSO 4 )o(rMg 2+ +rCa 2+ ) Sulfate type, magnesium subtype

HCO 3 is absent, water is acidic
2

Chloride-calcium (rHCO 3 +rSO 4 )o(rCa 2+ +rMg 2+ ) Chloride

HCO 3 is absent, water is acidic

Fig. 4.3. Graphical representation of chemical composition of oilfield waters: vertically lined areas
represent calcium chloride waters; horizontally lined areas represent alkaline waters (after Tolstikhin, in:
Vassoyevich, 1954, p. 112). Sampling areas: (1) Lake Onega; (2) Darasun mineral springs; (3) Lake Baikal;
(4) Okha oilfield waters, Sakhalin Island; (5) World Ocean; (6) Usol’e Sibirskoye; (7) Ukhta oilfield waters,
Russia; and (8) Grozny oilfield waters, Russia.

this scheme, one may chemically classify water, for instance, as sodium bicarbonate
type, or calcium chloride type, depending on the position the prospective water
occupies in the diagram. The representative oilfield waters fall within the dashed area.
Additional information on the chemistry of petroleum brine waters and their genetic
coefficients is presented in Table 4.2 and Fig. 4.4.