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Influence of geothermobaric conditions on the properties and composition of gas condensates of the Sudochye trough
Влияние геотермобарических условий на свойства и состав газоконденсатов Судочьего прогиба
- Institute of Geology and Exploration of Oil and Gas Fields (IGIRNIGM), Tashkent, Uzbekistan
Highlights
- Reservoir temperature in Jurassic rocks: 45.0–149.2 °C at 1,470–3,807 m.
- Geothermal gradient 3.8–4.0 °C/100 m in the southern part of the trough (Raushan, Kungrad).
- North Aral to East Muynak: temperature 11–15 °C higher with a depth difference of 49–90 m.
- Upper Jurassic top at 1,098–2,390 m: initial pressure 11.8–25.4 MPa. Middle Jurassic top at 1,680–2,727 m: 18.2–29.2 MPa.
- Zone I: 16.5–25.0 MPa and 52–80 °C. Zone II: 25.0–38.5 MPa and 75–149.2 °C.
- Pressure anomaly coefficient 0.96–1.05 in 70% of measurements; elsewhere 1.06–1.19.
Keywords
- reservoir temperature
- reservoir pressure
- geothermal gradient
- Sudochye trough
- Ustyurt
- Jurassic
- gas condensate
Summary
The authors, of the Institute of Geology and Exploration of Oil and Gas Fields (IGIRNIGM), study how reservoir pressure and temperature change the properties of gas condensates in the multi-layer fields of the Sudochye trough. Pressures in the Jurassic rocks are mostly normal hydrostatic (70% of point measurements, anomaly coefficient 0.96–1.05), less often raised (1.06–1.19). At the top of the Upper Jurassic, at 1,098–2,390 m, initial reservoir pressure rises from 11.8 to 25.4 MPa from Shege towards Urga and towards Raushan and Kungrad; at the top of the Middle Jurassic, at 1,680–2,727 m, it is 18.2–29.2 MPa.
Present reservoir temperature in the Jurassic rocks is 45.0–149.2 °C at 1,470–3,807 m. It falls from the north-west (Murun, Kabanbay) to the south-east (Shege). From North Aral east to East Muynak it rises by 11–15 °C with a depth difference of only 49–90 m; the authors link this to heat and mass carried up along the Aral-Kyzylkum fault, which runs from south to north. Temperature is highest in the deep southern part of the trough (Raushan, Kungrad), where the geothermal gradient is 3.8–4.0 °C/100 m. Temperature and pressure rise together with depth (R² = 0.85).
The authors divide the trough into two thermodynamic zones. In zone I, at 16.5–25.0 MPa and 52–80 °C, the condensates of the Upper Jurassic (East Berdakh, Uchsay, Surgil) are light. In zone II, at 25.0–38.5 MPa and 75–149.2 °C, condensates are medium to heavy and solid bitumens are common, from asphaltites to kerites and anthraxolites; anthraxolites occur in deep horizons of East Berdakh well 13 and North Berdakh well 1 (3,800 m). With depth, condensate density and the share of aromatic and naphthenic hydrocarbons increase.
How to cite
N. M. Akramova, S. A. Rubtsova and L. S. Akhmedzhanova (2008). Influence of geothermobaric conditions on the properties and composition of gas condensates of the Sudochye trough. O‘zbekiston neft va gaz jurnali (Uzbek Journal of Oil and Gas), No. 4, 2008, pp. 24–25. https://drive.google.com/file/d/1Fin6Cp-v-eVHISg8qMXcGpbOWPswWy-4/view