北部湾盆地乌石凹陷东区流沙港组三段储层物性主控因素及分布规律

摘要

Fan delta reservoirs in the 3rd member of Liushagang Formation in the eastern Wushi Sag, Beibu Gulf Basin are characterized by large thickness of sand bodies, complicated lithology, rapid change of physical proper⁃ties, and unclear distribution of good⁃quality reservoirs, which restricts further development. The controls of the sedimentary environment, diagenesis and structure on reservoir physical properties were studied using drilling, logging and testing data. Shale content, sorting and psephicity have a huge influence on physical properties. Compaction and dissolution controlled later reservoir porosity evolution. Paleotectonics and fracture systems con⁃trolled acid fluid migration direction and path. Underwater distributary channels of the proximal outer fan delta front near the large fault which exhibited low matrix content, good sorting and psephicity, good physical proper⁃ties, high productivity and were good⁃quality reservoirs in the study area.%南海北部湾盆地乌石凹陷东区流沙港组三段扇三角洲储层砂体厚度大、岩性复杂、物性变化快、优质储层展布不清，制约了下一步的开发部署。利用分析化验、钻测井和测试资料，从沉积环境、成岩作用和构造三方面来探讨其对储层物性的控制作用。沉积环境中的泥质杂基含量和分选磨圆对物性影响较大；成岩作用中的压实作用和溶解作用决定了孔隙的后期演化；古构造和断裂系统控制了酸性流体运移方向和路径。靠近大断裂的扇三角洲外前缘近端的水下分流河道储层，由于杂基含量低，分选磨圆较好，溶解作用强，物性较好，产能较高，是研究区的优质储层。