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Increasing oil recovery and development rates of non-Newtonian oil deposits on the basis of an innovative technology
Повышение нефтеизвлечения и темпов разработки залежей неньютоновских нефтей на основе инновационной технологии
- Tashkent State Technical University, Tashkent, Uzbekistan
Highlights
- Khaudag pilot, 1978–1980: geothermal water at 71–73 °C at the wellhead let into the oil layers under natural pressure.
- Uzen (Kazakhstan), 1975: horizon XXIV, 90–100 °C at 1,980–2,300 m; 70–75 °C after gas lift.
- Reservoir temperatures: Lyalmikar 41–43 °C, Kokaydy 57–58 °C, Khaudag 31–32 °C, Amudarya 52 °C, Koshtar 57 °C.
- Depths of the oil layers: Khaudag 260–320 m, Lyalmikar 895–950 m, Kokaydy 1,204–1,280 m, Amudarya 1,200–1,250 m, Koshtar 1,275 m.
- Geothermal water at 120–180 °C at depths of up to 3,000–5,000 m; possible local gradients of 0.04–0.06 °C/m and more.
- Heat losses: 30–35% (upward flow) and 35–40% (downward flow) with surface injection, against 10–15% with in-well transfer.
Keywords
- geothermal water
- geothermal flooding
- enhanced oil recovery
- heavy oil
- Khaudag
- Surkhandarya
- reservoir temperature
Summary
Oil fields with viscous, non-Newtonian oil in Uzbekistan, among them Lyalmikar, Kokaydy, Khaudag, Amudarya and Koshtar in the Surkhandarya and South-West Gissar regions, have been produced for 40–65 years and more and have low oil recovery factors of 0.1–0.3. Reservoir temperatures in these fields are 31–32 to 57 °C and oil viscosity in the reservoir is 76–1,280 mPa·s, while water viscosity is 0.49–0.95 mPa·s, so water breaks through to producing wells and their output is 85–90% water and more.
Geothermal flooding was first used on an industrial scale in 1975 at the Uzen field in Kazakhstan, from horizon XXIV with 90–100 °C fluid at 1,980–2,300 m; water lifted by gas lift was 70–75 °C. In 1978–1980 pilot work at the Khaudag field let geothermal water with a wellhead temperature of 71–73 °C flow under its own pressure into the oil layers; well output, reservoir temperature and pressure rose. The author proposes letting geothermal water from deeper layers flow directly into the oil-bearing layer inside the well, without lifting it to the surface. This cuts heat losses from 30–40% in conventional injection, and up to 60–70% when hotter water is injected, to 10–15%. Wastewater would be returned to the geothermal horizons.
Measurements of oil viscosity between 30 and 98 °C show a sharp fall up to 60–70 °C; at 80–98 °C the oils behave as Newtonian fluids. At Amudarya, viscosity falls from 4,200 cSt at 30 °C to 22 cSt at 98 °C. Geothermal water at 120–180 °C lies at depths of up to 3,000–5,000 m in the region, in layers below the oil fields. The author expects that local geothermal gradients of 0.04–0.06 °C/m and more may bring this water to shallower depths, and calls for hydrogeological surveys to establish its resources. He sets the aim of raising oil recovery in these deposits to 0.85–0.90.
How to cite
O. M. Chariev (2008). Increasing oil recovery and development rates of non-Newtonian oil deposits on the basis of an innovative technology. O‘zbekiston neft va gaz jurnali (Uzbek Journal of Oil and Gas), No. 1, 2008, pp. 15–18. https://drive.google.com/file/d/1xMt34kOd4Ysh5HDfJxVcT5OXd8iRCq59/view