塔里木盆地巴麦地区东河塘组储集层特征与成岩作用

Reservoir characteristics and diagenesis of Devonian Donghetang Formation in Bachu-Maigaiti area

通过普通薄片、铸体薄片、扫描电镜以及测井等分析手段,对巴麦地区东河塘组上砂岩段和下砂岩段的沉积特征、岩石学特征、成岩作用进行了详细分析。东河塘组沉积环境为滨岸相,具有较高的成分成熟度和结构成熟度,且上砂岩段的成分成熟度和结构成熟度都要高于下砂岩段。储集空间类型主要为溶蚀孔隙,其分布主要受粒度和粒间胶结物的影响,粒度较粗和钙质胶结的砂岩段溶蚀孔隙发育。主要的成岩作用为压实、胶结、胶结物溶蚀、石英颗粒碱性溶蚀、交代、重结晶以及构造破裂。根据成岩阶段划分标准,东河塘组处在中成岩阶段的B期。

According to the analyses of rock slice, cast slice, SEM and well logging data, the sedimentary, petrologic characteristics and diagenesis of the upper and the lower sandstone segments of the Donghetang Formation in the Bachu-Maigaiti area were studied. Deposited in littoral environment, the Donghetang Formation was featured by higher compositional maturity and textural maturity, and both of the 2 maturities were higher in the upper sandstone segment than in the lower one. Dissolution pores served as the main reservoir space, and their distribution was determined by grain size and intergranular material. For example, the dissolution pores were well developed in the sandstone segment with bigger grain size and calcareous cementation. The most important diagenesis effects included compaction, cementation, cement dissolution, quartz alkali dissolution, metasomasis, recrystallization and structure cataclasis. According to the division standard of diagenetic phase, the Donghetang Formation was in the B stage of middle phase.