Characteristic of sequence & sedimentory facies in Shijiachang northern of south-eastern Sichuan

There’re three sedimentory facies in Changxing Formation in Shijia Chang northern of south-eastern Sichuan, including platform slope, platform margin reef flat and open platform. Changxing Formation can be divided into two third-order sequences(SQ1&SQ2) and four fourth-order sequences. The mainly reservoir in Changxing Formation is the reef-bank type which mainly located in the HST unit of the third-order sequence.During early sedimention of Changxing Formation, it’s favorable for the development of the reservoir along Chi A log in the southern part. And during late sedimention, the bioclastic shoal and the exposed shallow-bank facies develop fast along the XL B log in the north which are the favorable facies for reservoir. Platform margin reef flat in Changxing Formation moves towards shelf and superposed developed.The development of he reservoir is affected by the sequence, sedimentory facies and the changes of the micro-landform.