镇泾地区延长组流体过剩压力分布特征及其与油气成藏的关系

Distribution characteristics of fluid overpressure and their relationship with hydrocarbon accumulation in the Yanchang Formation of Zhenjing area

镇泾地区中生界延长组油气聚集层位岩性油藏发育，为了揭示低渗透油藏成藏特征及油气运移和聚集规律，选取镇泾地区长7和长8油层组为主要研究对象，利用测井声波资料分析延长组泥岩压实特征与流体过剩压力分布特征。结果表明，研究区长7油层组过剩压力主要为8~13MPa，长8油层组过剩压力相对较低，只有极少区域达到10MPa，长7油层组烃源岩具有远远大于长8油层组的过剩压力分布，该过剩压力差是长7油层组油气运移到长8油层组储层的主要驱动力。相邻层位过剩压力差高值区是原油的高产富集区，而同层位过剩压力差相对低值区也是油气运聚的有利区。推测研究区东北部过剩压力差高值区和东南部大范围的过剩压力差低值区为有利油气富集区。

Lithologic reservoir developed well in Mesozoic Yanchang Formation of hydrocarbon accumulation area of Zhenjing area.In order to reveal the characteristics of low permeability reservoir formation and laws of hydrocarbon migration and accumulation in Zhenjing area,Chang7and Chang8members in Zhenjing area were selected as study targets to analyze the characteristics of clay compaction and fluid overpressure distribution in the Yanchang Formation.The results showed that the fluid overpressure of Chang7member ranges from8MPa to13MPa,and the fluid overpressure of Chang8member is lower and can reach to10MPa only in several areas.There are obvious differences in fluid overpressure between Chang7and Chang8members.The high overpressure difference offers the driving forces for oil and gas migrating from Chang7member to Chang8member.High oil production zones are areas where high overpressure difference exists between the two members and areas with relatively low overpressure difference are favorable for hydrocarbon migration and accumulation.The northeast and the southeast regions of the study area,which respectively have high overpressure difference and largescale low overpressure difference,are expected to be oil and gas enrichment zones.