西湖凹陷平湖斜坡有利相带内储层非均质性成因新认识  

New Insights into Reservoirs Heterogeneous Genesis of Favorable Facies in Pinghu Formation,Xihu Depression

作　　者：谢晓军 熊连桥 韩雅坤 李鑫 陈莹 Xie Xiaojun;Xiong Lianqiao;Han Yakun;Li Xin;Chen Ying(Research Institute Ltd.,China National Offshore Oil Corporation,Beijing 100028,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028

出　　处：《地球科学》2024年第4期1400-1410,共11页Earth Science

基　　金：“十三五”国家科技重大专项(No.2016ZX05024002);中国博士后科学基金(No.2021M693543).

摘　　要：河流-潮汐双向水流沉积环境中,水体方向、动力、化学属性变化频繁,储层矿物基础、成岩过程复杂多变、物性非均质性强,一直是制约其勘探开发的难点.以中国东海西湖凹陷平湖组为例,针对河流-潮汐背景中潮道和水下分流河道两种高能沉积微相,通过岩心观察、孔渗测试、光镜等方法,从物质基础、物性规律、主控因素3个方面开展研究.结果表明:(1)潮道中上部物性好,孔隙度平均18%、渗透率平均120 mD(1 mD≈10^(-3)μm^(2)),而潮道底部致密,孔隙度平均4%、渗透率平均0.05 mD;呈现非均质性的主要原因是碳酸盐胶结导致底部致密;(2)水下分流河道上部物性好,孔隙度平均5%、渗透率平均70 mD,而水下分流河道底部致密,孔隙度平均1%、渗透率平均0.01 mD;呈现非均质性的主要原因是高岭石充填导致底部致密.上述研究明确了西湖凹陷平湖组2种优势微相的非均质性成因,对深化河流-潮汐背景下储层非均质性规律及成因机制具有重要的理论指导意义;技术方法、研究成果可应用于东海盆地低渗砂岩储层油气勘探,对于中国近海、国外区块的深层碎屑岩储层油气勘探亦具有重要推广借鉴意义.Flow direction,dynamic and chemical properties change frequently in fluvial and tidal sedimentary environment,the reservoir mineral foundation and diagenetic process are complex and changeable,and the physical property is strong heterogeneity,which has always been the difficulty restricting its exploration and development.In this paper,Pinghu Formation in Xihu Depression of East Sea,China was taken as an example.Material basis,materiality pattern and main controlling factors were investigated in two high-energy sedimentary microphases,namely tidal channel and submerged divergent river channel.Methods include core observation,pore penetration test,light microscopy,isotope and inclusions.The results show follows.(1)The upper/middle part of tidal channel possessed good physical properties with an average porosity of 18%and permeability of 120 mD,while the bottom of tidal channel was dense with an average porosity of 4%and permeability of 0.05 mD.The main reason for the inhomogeneity is that the bottom is dense due to carbonate cementation.(2)The upper part of submerged diversion channel had good physical properties with an average porosity of 5%and permeability of 70 mD,while the bottom of submerged diversion channel was dense with an average porosity of 1%and permeability of 0.05 mD.The main reason for the inhomogeneity is that the bottom is dense due to kaolinite filling.The above analysis has important theoretical guiding significance to deepen the law and formation mechanism of reservoir heterogeneity under fluvial and tidal background.The technical methods and research results can be applied to the oil and gas exploration of low permeability sandstone reservoirs in the East China Sea basin,and have important reference significance for the oil and gas exploration of deep clastic reservoirs in offshore China and foreign blocks.

关 键 词：近海 深层 非均质性 碳酸盐岩 高岭石 石油地质学 

分 类 号：P618[天文地球—矿床学]