吐哈盆地柯柯亚地区致密砂岩气储层“甜点”类型及成因

"Sweet spot" types of reservoirs and genesis of tight sandstone gas in Kekeya area,Turpan-Hami Basin

柯柯亚地区中-下侏罗统水西沟群致密砂岩气资源丰富,对其储层"甜点"类型和成因的研究可为吐哈盆地乃至其他地区致密砂岩气的勘探开发提供借鉴。通过物性统计、岩心观察、薄片分析、裂缝统计、测井解释和产量对比等研究,认为吐哈盆地柯柯亚地区水西沟群致密砂岩气发育孔隙型和裂缝型2种"甜点"类型。在沉积微相、矿物组成、地层水研究及盆地埋藏史、盆地演化史模拟的基础上,指出特定的沉积微相(水下分流河道和河口坝)、相对较弱的压实作用和相对较强的溶蚀作用是孔隙型"甜点"形成的主要原因,而强烈的构造抬升运动和储层所处的特殊构造位置是裂缝型"甜点"发育的主控因素。综合研究认为,吐哈盆地孔隙型和裂缝型"甜点"是沉积、成岩和构造运动等多种因素共同作用的结果。

The Lower-Middle Jurassic Shuixigou Group in the Kekeya area is rich in gas resources of tight sandstone reservoirs,analysis of their reservoir ＂sweet spot＂ types and genesis is of certain reference significance in the tight sandstone gas exploration development in the Turpan-Hami Basin and other areas.By contrast of porosity and permeability,core observation,thin-section analysis,fracture statistics,log interpretation and production feature comparison,we summed up ＂sweet spot＂ reservoirs developed in the Shuixigou Group of the Kekeya area as two ＂sweet spot＂ types,i.e.the pored and fractured.Based on analyses of sedimentary microfacies,mineral compositions,formation water and simulations of basin burial history and basin evolution history,we concluded that specific sedimentary microfacies,relatively weak compaction and relatively strong dissolution are chief reasons of forming pored ＂sweet spot＂ reservoirs,while strong tectonic movement and local special tectonic locations control development of fractured ＂sweet spots＂ reservoirs.This comprehensive study showed that in the Turpan-Hami Basin,the formation of pored and fractured ＂sweet spot＂ reservoirs is a consequent result caused by interaction of deposition,diagenesis and tectonism.