Characteristics and forming mechanisms of evaporite platform dolomite reservoir in Middle Cambrian of Xiaoerbulake section, Tarim Basin

There was a high hydrocarbon potential in the evaporite platform dolomite of Middle Cambrian in Tarim Basin. Based on the outcrop observation and the comprehensive analyzes of common thin section, scanning electron microscope (SEM), cathodeluminescence (CL) technique and the geochemical data, we carried out the research on the characteristics of a dolomite reservoir which had deposited in the section of X in Tarim Basin during the Middle Cambrian. The results show that the Middle Cambrian rocks in the study area are of various types, and the reservoir's space mainly includes the dissolved pores and the collapsed caverns (the collapsed shadowing hole). We also studied the reservoir's forming mechanism through the assay of accompanying minerals and the analyses of the pore characteristics and geochemical characteristics. It indicates that the mechanisms in the study area include the atmospheric water denudation in syngenetic stage, the collapsing rock's stacking interaction in middle burial stage and the hydrothermal dissolution in deep burial stage. The former two mechanisms were controlled by the fluctuation of sea level, so they distributed widely. However, the distribution of the third mechanism is quite limited, because it was vertically accompanied by the faults and horizontally distributed along the formation, and it may alter the early generated dissolved pores.