南堡凹陷3号构造区古近系东营组/沙河街组不整合结构特征

Characteristics of Unconformity Structure Between Palaeogene Dongying Formation and Shahejie Formation in No.3 Tectonic Region of Nanpu Sag

南堡凹陷古近系东营组/沙河街组(Ed/Es)不整合结构普遍发育,不同区域的发育特征不尽相同,其中南堡凹陷3号构造区就显示出了明显的差异性。综合三维地震、测井曲线、钻井岩芯、物性分析等资料,系统分析南堡凹陷3号构造区Ed/Es不整合结构岩石学、测井响应、物性以及空间分布特征。结果表明:Ed/Es不整合结构可以划分为不整合面之上的岩石、风化黏土层和半风化层3层,其中风化黏土层发育程度较低;不整合结构具有不同的岩石学特征,不整合面之上的岩石风化程度最低,泥质含量高,风化黏土层风化程度高,物性最差,半风化层受改造程度高,物性最好;不整合结构的分布在平面和空间上较为一致,不整合面之上的岩石和半风化层岩石在顺物源方向上较为发育,在垂直物源方向上发育程度较低,风化黏土层在垂直物源方向上中部地区较为发育,在顺物源方向上欠发育;不整合结构发育程度上的非均一性对油气产生不同影响,其中不整合面之上的岩石和风化黏土层主要作为油气的封盖层,半风化层则主要作为油气运移的输导层。

The unconformity structure between Palaeogene Dongying Formation and Shahejie Formation（Ed/Es）in Nanpu sag is widely developed,and the development characteristics are different in distinct regions,especially in No.3 tectonic region of Nanpu sag.Combined with 3 Dseismic,well logging curves,drilling core,physical analysis and other data,the characteristics of lithology,logging response,physical property and spatial distribution of Ed/Es unconformity structure in No.3 tectonic region of Nanpu sag were systematically analyzed.The results show that Ed/Es unconformity structure can be divided into rocks above the unconformity,weathering clay layer and semi-weathered layer,and the development degree of weathering clay layer is low;the unconformity structure has different characteristics of lithology,the rocks above the unconformity have the lowest weathering degree and high shale content,and the weathering clay layer has high weathering degree and the worst physical property,while the semi-weathered layer suffers strongly modification and has the best physical property;the distributions of unconformity structure are more consistent in plane and space,and the rocks above the unconformity and the semi-weathered layer are more developed along the parallel direction of sediment sources,and are lower developed along the vertical direction of sediment sources,while the weathered clay layer is developed in the middle area along the vertical direction of sediment sources,and is undeveloped along the parallel direction of sediment sources;the heterogeneity of development degree of unconformity structure has different effects on oil and gas,the rocks above the unconformity and the weathering clay layer are mainly as sealing barrier for oil and gas,and the semi-weathered layer is mainly as a carrier bed of oil and gas migration.