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Using the potential of geothermal waters to increase the recovery of oil, gas and condensate and the flow rate of wells
Использование потенциала геотермальных вод для повышения извлечения нефти, газа и конденсата, дебита скважин
- Tashkent State Technical University, Tashkent, Uzbekistan
Highlights
- Reservoir pressure in aquifers deeper than 1,000–1,200 m: usually 1.1–1.2 times the hydrostatic head.
- Gas cooling in reservoirs: 1.5 to 4 K per 1 MPa of pressure drop; reservoir temperature falls by more than 10–15 K during production.
- Oil viscosity falls sharply on heating to 60–80 °C.
- Expected oil recovery from viscous oils: 0.75–0.85 (5–7 times higher); gas and condensate recovery up 10–25%.
- Estimated gain: 160–170 thousand tonnes of oil a year, 11,264–11,968 million soums a year.
Keywords
- geothermal water
- geothermal flooding
- enhanced oil recovery
- gas condensate
- reservoir pressure
- Surkhandarya
- Fergana valley
Summary
The author, of Tashkent State Technical University, builds on his earlier proposal to heat viscous oil with geothermal water. Earlier work used only the heat of the water; here he adds its pressure. In aquifers deeper than 1,000–1,200 m, reservoir pressure is usually 1.1–1.2 times the hydrostatic head, and some geothermal waters have abnormally high pressure. Letting this water flow inside the wells into overlying oil and gas layers can keep reservoir pressure at 1.1–1.2 of the hydrostatic head or higher and, with the best use of its energy, make producing wells flow on their own.
Oil recovery from viscous and highly viscous oil does not exceed 0.1–0.3. In gas and gas-condensate fields the expanding gas cools by 1.5 to 4 K for each 1 MPa of pressure drop, and reservoir temperature falls by more than 10–15 K during production, so condensate drops out in the reservoir; gas and condensate recovery is no more than 0.6–0.8. Oil viscosity falls sharply when it is heated to 60–80 °C. First candidates are oil deposits with reservoir viscosity of 25–30 cP and more, high wax and resin content and depleted reservoirs, such as Amudarya, Mirshadi, Lyalmikar, Khaudag and Koshtar in the Surkhandarya and West Gissar regions and Chimion, Palvantash, West Palvantash, South Alamyshik, Andijan, Sharikhan-Khodzhaabad, Boston, Khankyz, Changara-Galcha, Avval and East Avval in the Fergana region, as well as gas and gas-condensate deposits with low reservoir pressure.
The author expects the method to raise oil recovery from viscous oils to 0.75–0.85, or 5–7 times; to raise gas and condensate recovery by 10–25%; to cut the cost of developing viscous-oil fields by 80–90% compared with flooding from surface water sources; and to cut the cost of gas treatment at low-temperature separation plants by 30–50%. For fields with highly viscous oil he estimates the gain at 160–170 thousand tonnes of oil a year, worth 11,264–11,968 million soums a year. He notes that the technology can be put into practice once the resources and reserves of geothermal water in the oil and gas regions have been established.
How to cite
O. M. Chariev (2010). Using the potential of geothermal waters to increase the recovery of oil, gas and condensate and the flow rate of wells. O‘zbekiston neft va gaz jurnali (Uzbek Journal of Oil and Gas), No. 1, 2010, pp. 41–42. https://drive.google.com/file/d/13z6cOMrSOSnWSA2Er2Zj6ikgQpz60wxu/view