| Author's Name: GU Mingfeng, LI Wenzheng, ZOU Qian, ZHOU Gang, ZHANG Jianyong, L?譈 Xueju, YAN Wei, LI Kunyu, LUO Jing |
| Based on the observation of typical outcrops, cores and petrographic thin sections, combined with the experimental analysis data, the lithofacies palaeogeography, reservoir characteristics and their main controlling factors of the Cambrian Xixiangchi Formation in Sichuan Basin were studied. The results show that: (1) The Xixiangchi Formation is developed in the rimmed carbonate platform, and the Sichuan Basin is located in the interior of the limited platform as a whole, with the high-energy shoal facies developing on both sides of the Liangping-Chongqing platform depression; (2) The effective reservoirs are mainly developed in the middle and upper part of Xixiangchi Formation, dominated by grain dolomite, crystalline dolomite and algae dolomite. The reservoir spaces are consisted of dissolution pore, intergranular pore, intercrystalline pore and fracture, with porosity mostly at the range of 2%～5% and the average of 3.46%. (3) The formation and distribution of reservoirs are controlled by sedimentary facies, penecontemporaneous dissolution and supergene karstification. Reservoirs are mainly developed in the higher part of paleogeomorphology, and in the upper part of upward-shallowing cycle of sea water, and near the pinchout line of Ordovician. It is predicted that the areas of Hechuan-Guang’an and Nanchuan-Shizhu, as the high parts of palaeogeomorphology at the both sides of Liangping-Chongqing platform depression, are the favorable shoal reservoir zones, and Xichong-Guang’an-Tongnan area is the favorable karst reservoir zone. It is concluded that the Xichong-Guang’an area is the main target zone of natural gas exploration in the future. |
