Tectonic-Depositional Environment and Petroleum Exploration of Yingshan Formation in the Tarim Basin

Gao Huahua; He Dengfa; Tong Xiaoguang; Wen Zhixin; Wang Zhaoming

Abstract：Prototype basin restoration is of great significance to uncover the original tectonics-lithofacies paleogeography of the basin and is the foundation of petroleum exploration.Based on the newest data of outcrops,drillings,and seismic profiles,with the thoughtof the combination of basins and orogenic belts,this paper analyzed the sedimentary filling by employing the method of "point → line → faces",reconstructed the tectonic-depositional environment of the Yingshan Formation in the Tarim basin and pointed out the exploration direction of the petroleum.The sedimentary pattern of the Yingshan Formation exhibited the feature of the east-west differentiation in the Tarim basin.Shallow platform facies was developed in the west of the Tarim basin and deep-water shale basin faceis was developed in the east of the Tarim basin.The sedimentary pattern of the Yingshan Formation also exhibited the differentiation in the Taxi platform.The subtidal high-energy bank facies was developed in the zone distributed along the Shunnan-Tanggubasi-Yudong and was altered by the storm wave intermittently.However,the other regions of the Taxi platform developed the combination of restricted tidal flat faceis and grain bank facies in the lower part of the Yingshan Formation and the combination of interbank sea faceis and intraplatform bank facies in the upper part of the Yingshan Formation.The tectonic environment of the Tarim basin experienced the transformation from the extension environment to the environment which was compression in the south and was extension in the north during this stage The differentiation of the tectonic palaeogeography of the Taxi platform occurred because of the influence of the tectonic transformation.The intra-platform depression whose depth of water was above the wave base was developed along the ShunnanTanggubasi-Yudong and the intra-platform slope break belt was developed surrounding the intra-platform depression.The high-energy depositional environment was developed in the intra-platform depression,while the low-energy depositional environment was developed in the platform.The structure pattern differentiation of the Taxi platform was a response to the flexural deformation which was generated by the collision between the Tarim basin and the continental arc of North Kunlun and Altun during this stage The southern part of the Tarim basin showed the characteristics of foreland basin.The foredeep part was developed in North Kuniun and North Altun,the forebulge part was developed in Tangnan and the back-bulge part was developed in Shunnan-Tanggubasi-Yudong.