鄂尔多斯盆地东缘临兴-神府区块上古生界储层物性特征及其影响因素

Upper Paleozoic Reservoir Physical Property Features and Impacting Factors in Linxing-ShenfuBlock,Eastern Margin of Ordos Basin

针对目前对鄂尔多斯盆地东缘临兴-神府区块上古生界储层物性特征及其影响因素这方面的研究还不够全面和深入,影响了该区块的致密气资源评价、有利地段优选等工作开展的问题,本文通过对实验测试结果、扫描镜照片、基础地质资料等进行分析,分别从储集层岩石学特征、储层物性特征、成岩作用特征、成岩作用对储集物性的影响等方面开展研究。取得的认识有:①临兴—神府区块碎屑岩储层孔隙度主要集中为4%~10%,渗透率主要集中为0.1~1mD,属于特低孔特低渗储层;②研究区上古生界砂岩成岩阶段为中成岩阶段A期-B期,以中成岩阶段A期为主;③适量的刚性矿物成分对优质储层的形成起建设作用。一方面,刚性矿物可减缓致密化进程,使得部分原生孔隙得以继续发育和保存,促进了地层中流体的流动,加大了溶蚀几率;另外一方面,成岩中期含有较多石英的岩石易产生产生裂缝,可以很好地改善储层物性;④绿泥石薄膜的形成有利于保存粒间孔,进而有利于改善储层物性;⑤适量的可溶性组分是形成溶孔的必要条件,可溶性物质的溶蚀是优质储层发育的主要控制因素;⑥压实作用降低或破坏储层储集性能;胶结作用对储层的性能起到双重影响;溶蚀作用是改善砂岩储层物性的主要因素;⑦构造应力场产生的断裂和裂缝、残余的粒间孔为可溶性组分溶蚀提供了重要的渗流通道。

Considering the study on the upper Paleozoic reservoir physical property features and impacting factors in the Linxing-Shenfu block,eastern margin of Ordos Basin is insufficient on comprehensive and detail,thus will impact tight gas resource assessment and beneficial sectors optimization etc works carrying out in the block.The paper has based on tested results,SEM photos and fundamental geological data etc carried out analysis from reservoir petrological,physical and diagenetic features,as well as impact from diagenesis on reservoir physical property etc aspects.Cognitions archived have:①the porosity of clastic rock reservoir in the block is mainly concentrated between 4%~10%,permeability between 0.1~1m/d,belongs to very low porosity and very low permeability;②diagenetic stage of study area upper Paleozoic sandstone belongs to middle diagenetic stage phase A to phase B,mainly phase A;③appropriate amount of rigid mineral components can play construction role in high quality reservoir formation;on the one hand,it slows down densification process,part of primary pores can sequentially develop and preserve,promote strata fluid flow,increase dissolution probability;on the other hand,the middle diagenetic stage rocks contain more quartz thus easy to produce fissures and improve reservoir physical property well;④the formation of chlorite membrane is propitious to intergranular pores preservation,and then propitious to improve reservoir physical property;⑤appropriate amount of soluble components is necessary condition to form solution opening,the dissolution of soluble material is main control factor to develop high quality reservoir;⑥compaction can lower down or destruct reservoir reservation performance;cementation has dual impacts on reservoir performance;dissolution is main factor to improve sandstone reservoir physical property;⑦tectonic stress field can produce faults and fissures,residual intergranular pores can provide important seepage channels for dissolution of soluble components.