ZHANG Kuihua¹, CAO Zhongxiang², WANG Yue¹, ZHANG Guanlong¹, XUE Yan¹, WANG Shengzhu¹, QU Yansheng¹, WANG Yuxin¹

1. Exploration and Development Research Institute, Shengli Oilfield Company, SINOPEC, Dongying 257015, Shandong Province, China;

2. Shengli Oilfield Company, SINOPEC, Dongying 257001, Shandong Province, China

Abstract: The Lucaogou Formation in Bogda area is an important hydrocarbon source rock in the southern margin of Junggar Basin. The early study of sedimentary characteristics often focused on the mud shale on the north side of Bogda mountain or the glutenite on the south side of Chaiwopu Sag. However, the studies on the integrity of Bogda area are insufficient. Based on the detail observation and measurement of Lucaogou Formation at the typical outcrop around Bogda mountain, combined with the well logging and core data in Chaiwopu Sag, the stratigraphic characteristics, types and distribution features of sedimentary facies in this area were analyzed in detail, and the sedimentary evolution process was defined. The results show that Lucaogou Formation in Bogda area can be divided into the first member, the second member, the third member and the fourth member from bottom to top, in which the main sedimentary facies of the nearshore subaqueous fan, turbidite fan,semi-deep lake and deep lake are developed. During the sedimentation of the first and the second member of Lucaogou Formation, the nearshore subaqueous fan was widely distributed in Chaiwopu Sag, the turbidite fan and the semi-deep lake were mainly distributed to the north of present Bogda mountain. During the sedimentation of the third and the fourth member of Lucaogou Formation, the scale of the nearshore subaqueous fan and the turbidite fan decreased as the relative lake level rose, and the semi-deep lake and deep lake facies were widely distributed in the studying area, resulting in the development of large-scale high quality source rocks.