塔中西部上奥陶统良里塔格组同生喀斯特储层成因分析

Origin of syndepositional karst reservoir of the Upper Ordovician Lianglitage Formation in the west of Center Tarim Basin,China

通过岩心观察、薄片鉴定、孔渗测定以及地球化学测试,分析了塔中西部上奥陶统良里塔格组灰岩储层的基本特征及成因。良里塔格组储层主要发育于碳酸盐岩台地边缘的滩相颗粒灰岩中,储集空间类型主要包括粒内溶孔、铸模孔、非组构选择性溶孔、溶洞以及构造缝,属于低孔低渗储层类型。根据铸体薄片、成岩组构特征以及微量元素和碳氧同位素的综合分析,认为这些次生溶蚀孔洞的形成主要与同生喀斯特作用的改造密切相关,台缘滩相颗粒灰岩中的大气水透镜体为储层发育的有利位置。

The formation of a carbonate reservoir is mainly controlled by such factors as deposition, diagenesis, and structure. Based on this opinion and the basic data as core, thin slick, reservoir property and geomorphic features, the authors analyse the characteristics and origin of the limestone reservoirs of the Upper Ordovician Lianglitage Formation in the west of Center Tarim Basin. In study area, the reservoirs in the Lianglitage Formation mainly exist in the grain limestone bank of the carbonate platform margin. The main reservoir spaces involve the intragranular solution pore, moldilie pore, non-textural solution pore, cave as well as tectonic fissure. The reservoir types belong to that of low-porosity and low-permeability. According to the analyses of the infusion thin slick, diagenesis texture characteristics and microelements and C-O isotopes, such opinion is presented that the dissolution space is correlated with syngenesis karst, and the meteorological water-diagenesis lens in grain limestone bank on the platform margin are the favorable locations of reservoirs.