米仓山—南大巴山西段深部构造特征及对页岩气成藏的控制

Micangshan Mts.-South Dabashan Mts.West Segment Deep Part Tectonic Features and Shale Gas Reservoiring Control

以区域构造与沉积特征为指导,基于二维地震勘探成果,结合镇地1井钻孔数据,对米仓山隆起与南大巴山西段过渡区的深部构造特征进行剖析,并探讨了构造对页岩气成藏的控制作用。研究表明:区内主要发育倾向NE的逆断层,纵向贯穿区内寒武系至志留系主要地层,向上、向下分别收敛于志留系、震旦系滑脱层。深部表现为双重构造特征,即以志留系底部滑脱层为界面,上覆地层起伏较大,下伏地层相对稳定。牛蹄塘组受构造影响较小,多处目的层垂向临近构造相对简单,表明页岩气富集的封盖条件良好。受构造控制影响,目的层西北浅、东南深,主要为1500~3000 m,埋深适中;厚度较大且分布均匀,主要为80~100 m;储层具备封隔性,Ⅰ类含气区连续分布,含气性较好。研究区成藏特征优良,有利区可供后续工作参考。

Under the guidance of regional tectonics and sedimentary features,on the basis of 2D seismic prospecting results combined with well ZD No.1 drilling data have carried out anatomy of the Micangshan Mts.uplift and south Dabashan Mts.west segment transitional zone deep part tectonic features,discussed tectonic control on shale gas reservoiring.The study has shown that in the area mainly developed dip NE reverse fault,longitudinally penetrated Cambrian-Silurian strata,upwardly,downwardly restrained by Silurian,Sinian decollement zones respectively.Deep part presents duplex features i.e.taking Silurian bottom decollement zone as an interface;overlying strata have larger undulation,underlying strata relatively stable.The Niutitang Formation has less structural impact,multiple targets neighboring structures relatively simple indicated better shale gas enrichment capping condition;impacted by structural control,target northwest shallow,southeast deep,buried depth well situated mainly 1,500~3,000m;thickness larger and evenly distributed,mainly 80~100m;reservoir isolated well;category I gas-bearing area continuously distributed with better gas-bearing property.So that study area reservoiring features excellent,favorable areas can be reference for subsequent works.