POOL FORMING PATTERN AND PROCESS OF THE UPPER PERMIAN-LOWER TRIASSIC, THE PUGUANG GAS FIELD, NORTHEAST SICHUAN BASIN, CHINA

As the two wells (Puguang 1 and Puguang 2) have produced a large amount of commercial natural gas from the Upper Permian Changxing Formation and Lower Triassic Feixianguan Formation in the northeast of Sichuan Basin,the Puguang natural gas field has become the biggest in the basin.The Upper Permian Changxing Formation reservoir rock is dolomite and coral shoal of platform margin facies.The Lower Triassic Feixianguan Formation reservoir rock is calcirudite shoal and ollite shoal of open shallow marine platform facies.The reservoir space is mainly dissolved pores buried late.Natural gas comes from the Lower-Middle Cambrian,Lower Permian,Upper Permian source rock.It is very important that,the Puguang paleotrap and gas pool are affected by the Yanshan and Himalayas tectonic movements.The Puguang gas pool is a structural-lithologic pore gas pool which has experienced primary oil pool stage,gas pool stage and reformation and definition stage.It is significative for exploration in the northeast Sichuan Basin.