三肇地区青山口组泥岩盖层封气有效性研究

ESEARCH ON SE ALING EFFECTIVITY OF THE MUDSTONE CAPROCK OF QINGSHANKOU FORMATION IN SHANZHAO REGION OF SONGLIAO BASIN

在深入分析该区青山口组泥岩盖层各种封闭能力的基础上，根据泥岩封气所要求的最低排替压力标准，利用该区泥岩排替压力随埋深的变化关系，得到该区青山口组泥岩开始具物性封闭能力的深度为５０～１５０ｍ，对应时间为距今１２０．２～１１９．７Ｍａ。而上侏罗统气烃岩开始排气时间为距今１４８Ｍａ，在１４２～１３６Ｍａ达到排气高峰。表明该区青山口组泥岩盖层封闭能力开始形成时期远远晚于上侏罗统气源岩的大量排气期，封气有效性差，这是该区目前只找到中小型气田而找不到大气田的主要原因。

Based on the analysis of each kind of sealing ability of the mudstone caprock of Qingshankou formation in Sanzhao region and according to the lowest standard of mudstone sealing gas , we arrive at the conclusion that the depth at which the mudstone caprock of Qingshankou formation began to form the sealing ability is 50～150 m,its homologous time is 120.2～119.7 Ma to now, the time at which the source rock of upper Jurassic Series began to expel gas is 148 Ma to now. The time of highest gas expulsion is at 142～136 Ma to now. This indicates that the formation time of the sealing ability of the mudstone caprock of Qingshankou formation is obivously later than that of the highest expulsion of upper Jurassic series. Its sealing effect is poor. This is why only middle-sized and small gas fields can be found in the region.