柴达木盆地西部下干柴沟组下段碎屑岩储层物性差异主控因素分析  

Main controlling factors of clastic reservoir property difference of Lower Ganchaigou Formation in western Qaidam Basin

作　　者：伍劲 刘占国 朱超 宫清顺 宋光永 刘灿星 WU Jin;LIU Zhanguo;ZHU Chao;GONG Qingshun;SONG Guangyong;LIU Canxing(Hangzhou Research Institute of Geology,PetroChina,Hangzhou City,Zhejiang Province,310023,China;College of Geosciences,China University of Petroleum(Beijing),Beijing City,102249,China)

机构地区：[1]中国石油杭州地质研究院,浙江杭州310023 [2]中国石油大学(北京)地球科学学院,北京102249

出　　处：《油气地质与采收率》2021年第4期46-54,共9页Petroleum Geology and Recovery Efficiency

基　　金：国家“十三五”科技重大专项“大型岩性油气藏形成主控因素与有利区带评价”(2017ZX05001002);中国石油科技部项目“大型陆相沉积盆地砂体类型及控藏机制”(2019B-0309)。

摘　　要：利用大量的岩心实验分析资料系统地研究了柴达木盆地西部同沉积体系和不同区带之间下干柴沟组下段碎屑岩储层物性差异的主控因素,指出沉积环境、岩石学特征、砂体厚度、地层埋藏史、地温梯度背景和湖水古盐度的不同是造成储层物性差异的重要因素。柴达木盆地西部下干柴沟组下段广泛发育的三角洲平原分流河道砂、三角洲前缘水下分流河道砂和滨浅湖滩坝砂是优质储层发育的基本条件。储层砂体厚度、杂基含量和碎屑粒径是储层物性的重要控制因素,成岩作用对储层的演化和储集性能具有决定性作用,其中压实作用对储层物性影响最大,胶结作用是局部区带储层物性重要控制因素。同沉积体系三角洲平原分流河道砂的碎屑颗粒分选和杂基含量控制储层压实程度的差异,三角洲前缘水下分流河道砂和滨浅湖滩坝砂厚度控制了储层胶结强度差异;不同区带地层埋藏史和地温梯度背景造成储层的较大压实差异,湖水古盐度沿盐湖中心环带状分布造成储层在平面上的胶结强度差异。According to massive data from core experiments,we systematically studied the main controlling factors of the clastic reservoir property difference in the Lower Member of the Lower Ganchaigou Formation within the same sedimentary system but different plays in the western Qaidam Basin.The results reveal that the variations in sedimentary environment,lithological characteristics,sand body thickness,burial history,geothermal gradients and lake water paleosalinity contrib⁃ute heavily to the reservoir property difference.The distributary channel sand in the delta plain,the underwater distributary channel sand at the delta front and the beach-bar sand in the shore-shallow lake facies are widely developed in the Lower Member of the Lower Ganchaigou Formation of the western Qaidam Basin,providing a basis for high-quality reservoirs.Sand body thickness,matrix content and clastic particle are the important controlling factors of reservoir properties.Diagen⁃esis plays a decisive role in reservoir evolution and properties,among which compaction has the strongest impact on reser⁃voir properties,while cementation is a significant controlling factor in the local play.In the same sedimentary system,the difference in reservoir compaction strength is dominated by clastic particle sorting and matrix content of the distributary channel sand in the delta plain.Moreover,the variation in reservoir cementation strength is controlled by the particle size and thickness of both the distributary channel sand at the delta front and the beach-bar sand in the shore-shallow lake fa⁃cies.In different plays,different burial history and geothermal gradients result in the great variation in reservoir compaction,while the circular and banded distribution of lake water paleosalinity around the salt lake center lead to the reservoir cementation difference on the plane.

关 键 词：同沉积体系 不同区带 储层物性差异 压实作用 胶结作用 柴达木盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]