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Distribution of hydrogen sulphide formation waters in the Lower Paleogene deposits of the Surkhandarya artesian basin
Распространение сероводородных пластовых вод в нижних палеогеновых отложениях Сурхандарьинского артезианского бассейна
- Institute of Geology and Exploration of Oil and Gas Fields (IGIRNIGM), Tashkent, Uzbekistan
Highlights
- Lyalmikar, wells 85, 113, 122 and 165 (horizons IV–V, 1,045–1,071 m): H₂S 52.7–207.4 mg/L, pH 4.83–7.27, density 1.027–1.044 g/cm³.
- Kokayti, wells 61 and 82 (horizon II, 1,214–1,240 m): H₂S 57.8–166.6 mg/L, pH 4.53–7.30, density 1.057–1.080 g/cm³.
- Mirshadi, wells 40 and 42 (1,188–1,221 m): H₂S 20.4–95.2 mg/L, pH 6.88–7.54.
- Redox potential −50 to −450 mV; strongly sulphide waters −100 to −450 mV.
- Estimated average temperature of the oil–water layer: 50–70 °C.
Keywords
- hydrogen sulphide water
- formation water
- mineral water
- Surkhandarya artesian basin
- Paleogene
- Lyalmikar
- Kokayti
- Mirshadi
Summary
The authors, of the Institute of Geology and Exploration of Oil and Gas Fields (IGIRNIGM), describe where hydrogen sulphide water occurs in the Surkhandarya artesian basin and how it forms. In the basin it is found mainly in Paleogene rocks, chiefly in Paleocene carbonate reservoirs, at fields such as Uchkyzyl, Khaudag, Lyalmikar, Kokayti, Old Termez, Jayrankhana and South Kurganche, and less often in the Eocene.
Formation water sampled in June 2018 from Lower Paleogene aquifers contained 52.7–207.4 mg/L of hydrogen sulphide at Lyalmikar, 57.8–166.6 mg/L at Kokayti and 20.4–95.2 mg/L at Mirshadi, which places it among weakly to strongly sulphide mineral waters. The redox potential of the waters is −50 to −450 mV.
The authors name five conditions for the formation of sulphide water: sulphate-bearing host rocks and oil deposits, faulted anticlinal structures, a reducing hydrochemical setting, hydrodynamic conditions and geothermal conditions. They place the oil–gas–water layer at an average depth of 500–1,000 m and, from the geothermal gradient, estimate its average temperature at 50–70 °C; the sampled intervals in their table lie at 1,045–1,240 m.
How to cite
S. R. Burieva, Kh. F. Khudoyberdiev and K. B. Yusupov (2023). Distribution of hydrogen sulphide formation waters in the Lower Paleogene deposits of the Surkhandarya artesian basin. Geologiya fanlari universiteti xabarlari (Bulletin of the University of Geological Sciences), No. 3, 2023, pp. 19–23. https://files.uzgeouniver.uz/media/files/%D0%92%D0%B5%D1%81%D1%82%D0%BD%D0%B8%D0%BA_3_2023.pdf