Sedimentary Evolution Characteristics of Middle Cambrian Carbonate Platform in Tabei Area

Tabei area is an important area of Cambrian ultra deep exploration in Tarim Basin. Middle Cambrian dolomite reservoirs are developed and the relationship between reservoir and cap rock configuration is complex. Therefore, the study of sedimentary facies types and their distribution characteristics is of great significance for the next exploration plan in the region. This study is based on drilling and seismic data within the work area, and comprehensively analyzes the sedimentary evolution process of the Middle Cambrian platform in the Tabei area through petrology, seismic facies, and well connected sedimentary facies. The research results indicate that the Middle Cambrian in the study area is a typical bordered platform, which is influenced by ancient terrain and develops (evaporates) tidal flats, reef shoals, platform edge reef shoals, slopes, and basins from west to east. The overall trend of the facies belt shows an eastward migration. The Taiwan region mainly develops tidal flat, evaporative tidal flat, and granular beach, further divided into six microfacies such as argillaceous dolomite and micritic dolomite. Six stages of reef shoals are developed at the edge of the platform, stacked in an aggradation progradation manner. Based on comprehensive analysis, it is believed that in addition to the platform edge reef beach body, the dolomite behind the reef beach is another favorable facies zone with good exploration potential.