Reef and shoal facies reservoir prediction of Changxing Formation in eastern Sichuan and northern Chongqing

There are four sedimentary facies developed in Changxing Formation in eastern Sichuan and northern Chongqing,including intraplatform trough(deep water basin),platform slope,platform margin reef flat and open platform.Reef and shoal facies reservoir located in Kaijiang-Liangping intraplatform trough is the most important layers for oil and gas exploration.Crystal dolomite is the main lithology of reef and shoal facies reservoir,with wide area of distribution,great thickness and good physical property.Based on the analyses of sedimentary facies,logging facies and seismic facies,the geological model of the reef and shoal facies reservoir is established through the known rock-electricity transform pattern and logging response and the analysis of seismic reflection characteristics and geology property of reef and shoal.The obvious chimney effect on reef and shoal reservoir is defined.Based on the geological model established as the seismic inversion constraint,combined with regional geological information,the favorable zones ofreefand shoal reservoir and dolomite distribution are predicted.