塔里木盆地先巴扎地区小海子组碳酸盐岩储集层主控因素分析

Main controlling factors of carbonate reservoirs of Xiaohaizi Formation in Xianbazha area,Tarim Basin

通过岩心、薄片鉴定、扫描电镜、测井、储层地球化学等大量资料,分析了巴楚先巴扎地区石炭系小海子组储层基本特征及控制因素。小海子组储集层岩性主要为灰岩、云质灰岩、灰质云岩和白云岩,储集空间类型主要为粒间溶孔、粒内溶孔、晶间溶孔和裂缝,储层类型主要为裂缝-孔隙型和裂缝型。小海子组碳酸盐岩储集层受控于多重因素的影响,沉积相是储集层形成的基础,研究区内台内滩是有利储层发育的相带;溶蚀作用包括暴露溶蚀和埋藏溶蚀,是储集层发育的重要控制因素,渗流粉砂、氧化铁和大量溶蚀孔洞的发育等现象是暴露溶蚀的重要证据,而萤石、针状溶蚀孔洞、方解石碳氧同位素异常等均指示埋藏岩溶的存在;白云岩化在一定程度上促进了储集层的发育;构造破裂作用是最重要的储集层发育的控制因素之一,有利于裂缝型储集层的发育,并为溶蚀作用的发生提供良好的渗流通道,扩大溶蚀作用范围。

The basic characteristics and controlling factors of the Carboniferous reservoirs of the Xiaohaizi Formation in the Xianbazha area of the Tarim Basin have been studied based on core and thin section analysis, scanning electron microscopy, well logging and reservoir geochemical data. The Xiaohaizi reservoirs are mainly composed of limestones, dolomitic limestones, calcareous dolomites and dolomites. The reservoir porosity includes intergranular, intragranular and intercrystalline dissolved pores and fractures. The reservoirs are mainly of fracture-pore type and fracture type. The carbonate reservoirs in the Xiaohaizi Formation are controlled by many factors. Sedimentary facies is the foundation for reservoir formation. Favorable reservoirs are found in the platform shoal in the study area. Exposure erosion （proved by seepage powder sands, iron oxides and a large number of pores ） and burial erosion （proved by fluorites, needle-like pores, carbon and oxygen isotopic anomalies） play important roles in reservoir development. Dolomitization promotes reservoir development to a certain extent. The tectonic fracture effect contributes to the development of fractured reservoirs, and offers a good channel for the occurrence of seepage erosion, which expands the scope of denudation.