沁水盆地煤系地层游离气成藏条件分析

Reservoir-forming Conditions of Free Gas in Coal Measure Strata of Qinshui Basin

沁水盆地面积大,煤系地层游离气资源丰富,但多年勘探未获突破,主要原因是忽视了后期构造活动对游离气聚集成藏所产生的影响。对沁水盆地构造演化及煤系地层游离气的运移成藏进行深入研究分析,认为喜山期沁水盆地产生了大量的走滑断层,以前形成的大部分游离气藏被破坏,游离气藏被调整与改造,成藏关键取决于走滑断层控制。这些走滑断层是游离气运移和逸散通道,导致早期形成的山西组(P1s)、太原组(C3t)古气藏向石盒子组(P1-2sh)迁移或逸散。以此为依据,对沁水盆地游离气的有利成藏层位和区域进行了预测。

In Qinshui Basin , area was large , free gas resources were rich in coal-measure strata , but exploration has not been breakthrough for many years , the main reason was that the effect of tectonic activity at the late stage on free gas accumulation was ignored.Through the in-depth study of tectonic evolution and migration and accumulation of free gas in coal strata of Qingshui Basin , it was considered that large strike-slip faults were formed in Himalayan Period , the most of previously formed free gas reservoirs were damaged.Thus the migration of free gas for the 3 rd time was induced , and serious adjustment and reconstruction of free gas were caused , the key of hydrocarbon accumulation was controlled by strike-slip faults.They were the channels of the free gas migration and diffusions.On the basis stated above , the beneficial horizons of hydrocarbon accumulation are predicted in Qingshui Basin.