尼日尔Agadem区块中-新生代储层微观特征分析

Microcharaters of mesozoic-cenozoic reservoir in agadem block of Niger

通过岩石薄片、扫描电镜、黏土矿物X衍射、压汞测试分析等资料,从储层的岩性、成岩作用、储集空间等方面,对尼日尔Agadem区块白垩系储层的微观特征进行了研究,并分析了储层发育的控制因素.结果表明,研究区储层以石英细砂岩为主,结构成熟度低-中等;储集空间类型以原生孔隙为主,其次为粒间溶蚀孔隙;储层主要处于中成岩A期阶段,成岩作用弱-中等.沉积作用是储层发育的重要控制因素,最有利的沉积微相为辫状河三角洲前缘水下辫状河道及河口坝.成岩作用对于储层主要表现为建设性作用,白垩系Yogou组上部储层因碱性成岩作用形成次生溶蚀孔隙,储层物性有一定改善.该研究对于加深尼日尔Agadem区块储层的认知具有重要意义.

This paper studied the microcharacters and controlling factors of a mesozoic-cenozoic reservoir in Agadem block of Niger from aspects such as lithology,diagenesis and pore texture based on the petrographic thin section,scanning electron microscope,and formation test data including the and clay mineral X-ray diffraction and mercury injection experiment.The results showed that the reservoir in the study area is primarily composed of quartz sandstone of fine grain size,with high compositional maturity and moderate-low textual maturity.Primary intergranular pore is the main pore type,followed by intergranualar dissolved pore,intragranualar dissolved pore,cement dissolved pore,microfracture and micro-pore.The diagenesis of a cretaceous reservoir is in a middle digenetic stage.Reservoir development is mainly controlled by the lithology of parent rocks,deposition and digenesis.Among these,deposition is the key factor,and the underwater distributary channel and mouth bar are better sedimentary microfacies in the study area.Generally,diagenesis plays a positive role in reservoir development and Yogou formation of cretaceous is mainly affected by alkali digenesis.