鄂尔多斯盆地延长探区下古生界热演化史

Thermal evolution history of the lower paleozoic in Yanchang exploratory area of Ordos basin

通过钻井和试气资料,统计了延长探区马家沟组现今地层温度.应用地化资料,对马家沟组烃源岩热演化程度进行了评价;应用多种古地温研究方法恢复该区最大古地温梯度;采用将今论古方法探讨了该区各个时期的古地温梯度.在剥蚀厚度恢复的基础上,详细配置各个地层的岩性、物性、地化参数等指标,恢复了该区埋藏沉降史和热演化史.沉降史模拟表明晚三叠世(217～207Ma)为该区沉降的主要发育时期.热演化史模拟表明:延长探区马家沟组烃源岩在晚三叠世末期进入成熟阶段,晚侏罗世进入高成熟阶段,早白垩世达到过成熟干气阶段.下古生界烃源岩主生烃期为晚侏罗—早白垩世.

With the analysis of the gas-testing data, the Majiagou formation temperature in Yanchang area was calculated, and with the thermal evolution indicators and palaeogeothermal recovery, the thermal evolution stages of lower paleozoic were assessed. The paleo-geothermal gradient in different periods was discussed and the erosion thickness of the formation in this region was recovered. The thermal evolution history of lower paleozoic in Yanchang exploratory area was reproduced, showing that the main sedimentation period was late triassic（217-207 Ma）, the lower paleozoic source rocks reached the maturity stage in the end of late triassic and reached the high maturity stage in late jurassic. The main gas generation period of the lower paleozoic in Yanchang area was from late jurassic to early cretaceous.