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

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.