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研究表明,柴达木盆地西南地区地震活动强烈,深、浅层均发现一系列与古地震有关的震积岩,形成一系列软沉积物变形构造,主要包括震积砂枕、砂球构造、枕状层、液化砂泥岩脉、层内错断、地裂缝、微褶皱纹理、沙侵蘑菇等。研究区震积岩的岩石类型则主要包括震褶岩、震裂岩、震塌岩、自碎屑角砾岩、自碎屑副角砾岩、液化角砾岩及震浊积岩等。地震活动使岩层产生大量的微裂缝,裂缝沟通了原有的孔隙,同时增加了储集层的储集空间,极大地改善了储集层的渗透性,并使原先不具渗透性的砂泥薄互层产生裂缝,成为输导层,这为在地震断裂系统附近寻找低渗透岩层中的高渗储层提供了新的方向。而地震断裂系统上倾的三角洲前缘水下分流河道、河口坝砂岩以及滨浅湖滩坝所构成的岩性圈闭必将成为柴西南地区岩性油气藏勘探的新领域。
The study shows that the seismic activity in the southwestern Qaidam basin is intense, and a series of seismite-related seismite rocks are found in the deep and shallow layers, forming a series of soft sedimentary deformation structures, including seismogenic sand pillows, Pillow layers, liquefied sand and mud veins, strata fault, ground fissures, microfold texture, invasion of mushrooms and other sand. The seismite rocks in the study area mainly include the seismogenic fold rocks, seismic rocks, collapsed rocks, self-detritus breccias, self-detrital breccias, liquefied breccias and turbidites. Seismic activities cause a large number of micro-cracks in the rock formation. The fractures communicate with the original pores and meanwhile increase the reservoir’s reservoir space, greatly improving the permeability of the reservoir and making the original impermeable sand and mud thin The fractures in the interbedded layers become the conducting layer, which provides a new direction for looking for the high permeability reservoirs in the low permeability rock formation near the seismic fault system. The uplifting delta front subaqueous distributary channel, estuary dam sandstone and coastal shallow lake dam of seismic fault system will surely become the new field of lithologic reservoir exploration in southwestern Qaidam basin.