塔里木盆地库车坳陷依南2气藏类型的判别

Type discrimination of Yinan 2 gas reservoir in Kuqa depression,Tarim Basin

依据塔里木盆地库车坳陷依南2气藏的碳同位素、烃源岩热解、储层分析化验、气藏压力、流体包裹体等资料的正、反演综合分析,对该气藏的成因类型进行判别。结果表明:依南2气藏侏罗系阿合组砂岩储层致密化发生在距今约11 Ma,而其烃源岩排烃高峰为距今5 Ma,储层致密化时间早于烃源岩大量排烃时间,为先致密后成藏的深盆气藏;依南2气藏具有气水倒置、相对负压的地质特征,成藏动力机制为气体分子膨胀力作用下的活塞式气驱水充注成藏机制;依南2气藏为早期大规模深盆气藏,晚期遭受调整改造,含气范围受南北断裂带控制。

According to forward and retrieval comprehensive analysis on the data of carbon isotope, pyrolysis of source rocks, reservoir analysis, pressure of gas reservoir, fluid inclusions of Yinan 2 gas reservoir in Kuqa depression, Tarim Basin, the genetic type of this gas reservoir was discriminated. The results show that the densification of sandstone reservoirs of Jurassic Ahe formation in Yinan 2 gas reservoir took place about 11 Ma ago, while hydrocarbon expulsion peak of source rocks in this reservoir dated from 5 Ma ago. Reservoir densification is earlier than massive hydrocarbon expulsion, and thus this reservoir is a deep-basin gas field with densification first and then reservoir formation. Yinan 2 gas reservoir has geological characteristics of gas-water inversion and relatively negative pressure, of which the dynamic mechanism of reservoir formation is shown as piston-type gas-drive water filling under the expansive force of gas molecular. ~inan 2 gas reservoir is a large-scale deep-basin gas reservoir in the early stage, while adjusts and modifies later, which leads to the gas-bearing range controlled by south-north fault zones.