Formation And Reservoir Evaluation Of Reef-bank Reseavoir In Casmbrian-Ordovician In Tazhong Area, Tarim Basin

The reef-bank reservoir is one of the important types of marine carbonate reservoir. In order to systematically analyze the distribution rules and the main control factors of the reef-bank reservoir, the thesis applied the analytical method of sequence stratigraphy, sedimentology and reservoir geology to study the distribution rules and geology conditions of reef-bank reservoirs in Cambrian-Ordovician of Tazhong area in Tarim basin. The study result indicates that the early paleozoic tectonic evolution has the characteristics of early extention and later compression.The dynamic conversion in regional plate margins give rise to the change of platform structure style, palaeogeomorphic differentiation and sedimentary framework, which control the distribution of the reef-bank reservoir. Eustatic sea level change and platform structure styles control the development types of reef-bank and the transference of reef-bank facies. The types of the sedimentary facies control the rock type of the reservoir. Different sequence styles and system tract control the favorable reef-bank reservoir. The contributive and destructive diagenesis controls the reservoir quality.Based on the analyze of core, drilling, logging and outcrop data, the vertical model and lateral distribution for carbonate reef-bank reservoir in sequence stratigraphic framework are analyzed. The mudstone mound, organic reef, granule bank, dolomite flat is vertically accreted. Multiple reef-bank cycles accumulated thickness reef-bank complex. The reef-bank reservoir mainly developed in highstand system tract, which has good continuity vertically and bad continuity laterally. The reef-bank reservoirs mainly distribute along the carbonate platform margin in Lianglitage formation of the upper Ordovician in Tazhong area. The bank reservoir mainly developed in the platform in Yingshan formation of the lower Ordovician.The result shows that the reef-bank reservoirs of I type are characterized by the rock type of sparrudite, oolitic, bioclastic, micritic dolomite and the reservoir space of intragranular dissolved pore, intercrystalline pore, moldic pore,cavity-tectonic fracture and reservoir type of fracture-cavity, fracture-pore.The favorable bank reservoir in platform distributed in the area of well tazhong9-zhong11-zhong1-zhong13 in Penglaiba and Yingshan formation and the favorable reef-bank complex distributed in the area of well tazhong451- tazhong 45- tazhong 162- tazhong 161- tazhong 24-tazhong 26.