Genetic types and exploration potential of pre-Mesozoic dolomite reservoirs in Yakela fault arch and its surrounding areas, Tarim Basin

The analyses of drilling cores, thin sections and physical properties show that there are at least three types of pre-Mesozoic dolomite reservoirs in the Yakela fault arch and its surrounding areas, including weathering crust, exposed shoal and buried karst. The weathering crust reservoirs are mainly controlled by ancient buried hills, and serve as the most important reservoir type in the study area. The exposed shoal reservoirs are controlled by sedimentary microfacies, and the environments like platform shoal, atmospheric fresh-water leaching and organic acid corrosion play important roles during reservoir formation. The buried karst reservoirs are controlled by the fluid during the burial period and the diagenetic environment. The dolomite reservoirs in the study area are formed under various geological processes during different stages. Ancient tectonic location, favorable facies, constructive diagenetic effects (dolomitization, dissolution) as well as faults and fissures are the key elements for dolomite reservoir formation. The covering formations, especially the Shushanhe Formation, are decisive for hydrocarbon accumulation in dolomite reservoirs.