Earth Science Frontiers ›› 2010, Vol. 17 ›› Issue (4): 151-159.

• Article • Previous Articles     Next Articles

The thermal history reconstruction and hydrocarbon accumulation period discrimination of Gaoyou Depression in Subei Basin.

 LI  Ru-Feng, CHEN  Chi-Qiong, LI  E-Jun, SONG  Ning   

  1. 1Research Center of Basin & Reservoir, China University of Petroleum(Beijing), Beijing 102249, China
    2Jiangsu Oilfield Geological Science Research Institute of SINOPEC, Yangzhou 225009, China
  • Received:2010-01-24 Revised:2010-03-04 Online:2010-07-01 Published:2010-07-01

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Abstract:

Based on the analysis of the vitrinite reflectance, apatite fission track and homogenization temperature of fluid inclusions, we carried out the paleotemperature gradient calculation and thermal history reconstruction, and then identified the paleotemperature gradient of main tectonic units of Gaoyou Depression. The calculations of the paleotemperature gradient gave the following results: (1) from the vitrinite reflectance: 356 ℃/km in the deep concave zone, 439 ℃/km in the west part of the north slope and 332 ℃/km in the east part of the north slope; (2) from the apatite fission track: 314 ℃/km in the deep concave zone, 393 ℃/km in the west part of the north slope and 50 ℃/km in the east part of the north slope; (3) from the homogenization temperature of fluid inclusions: 29 ℃/km in the deep concave zone, 425 ℃/km in the west part of the north slope and 323 ℃/km in the east part of the north slope. Compared to the presentday geothermal gradient values, the paleogeothermal gradient was 07 ℃/km higher in the deep concave zone, 1015 ℃/km higher in the west part of the north slope and 421 ℃/km higher in the east part of the north slope. The comparative analysis showed that the difference of the ancient value and the present value of geothermal gradient is small in the deep concave zone and significant high in the slope zone. Through the comprehensive analysis of the buried historythermal history of typical singlewell and the homogenization temperature of fluid inclusions, we inferred that the accumulation period of the deep concave zone of Gaoyou Depression was between 4637 Ma and the accumulation period of the north slope was between 409375 Ma; the infill injection of the deep concave zone occurred earlier than that of the north slope. Then, it can be judged that the Sanduo period(E2s)was the main hydrocarbon accumulation period in Gaoyou Depression of the Subei Basin.

Key words: Gaoyou Depression, geothermal gradient, ancient temperature scale, thermal history reconstruction, hydrocarbon accumulation period

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