Structure characteristics and major controlling factors of platform margin microbial reef reservoirs: A case study of Xiaoerbulak Formation, Lower Cambrian, Aksu area, Tarim Basin, NW China
BAI Ying1, 2, LUO Ping1, 2, WANG Shi3, ZHOU Chuanmin1, ZHAI Xiufen1, WANG Shan1, YANG Zongyu1, 2
1. PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China; 2. School of Earth and Space Sciences, Peking University, Beijing 100871, China; 3. Petroleum Exploration & Production Research Institute, SINOPEC, Beijing 100083, China;
Abstract：The structure characteristics and major controlling factors of platform margin microbial reef reservoirs in the Lower Cambrian Xiaoerbulak Formation in the Aksu area, Tarim Basin were analyzed based on 5 outcrop sections, 162 thin sections, 12 SEM samples, 52 sets of porosity and permeability data. Macroscopically, small-scale microbial reefs form the platform margin. A single microbial reef has several microbial reef progradation complexes, including reef front, fore reef, reef crest, and back reef, but microscopically, they have different kinds of microstructures. The reservoir spaces in the reefs can be divided into microbial structure reservoir space, including fenestral, frame, moldic, and oversized dissolution pores, and non-microbial structure reservoir space, including microcracks and stylolites. The statistical results of porosity and permeability show that in the Yutixi Section, porosities and permeability of the microbial reef reservoirs are generally below 5% and 1.0×10-3 μm2 respectively, characteristics of extremely low porosity and permeability reservoirs; while the reef reservoirs in the Sugaitebulake Section have a wide porosity range between 3% and 10%, and permeability range between 0.1×10-3 μm2 and 50×10-3 μm2, and strong heterogeneity, are low-medium porosity, low-medium permeability reservoirs. This demonstrates different microbial reefs have big differences in physical properties, and even the reservoir in the same reef has obvious heterogeneity. Paleotopography controls the formation of microbial reefs and sedimentation controls the facies distribution and the primary porosity development. Dissolution, controlled by the former two factors, finally decides evolution of reservoir pores.
白莹, 罗平, 王石, 周川闽, 翟秀芬, 王珊, 杨宗玉. 台缘微生物礁结构特点及储集层主控因素——以塔里木盆地阿克苏地区下寒武统肖尔布拉克组为例[J]. 石油勘探与开发, 2017, 44(3): 349-358.
BAI Ying, LUO Ping, WANG Shi, ZHOU Chuanmin, ZHAI Xiufen, WANG Shan, YANG Zongyu. Structure characteristics and major controlling factors of platform margin microbial reef reservoirs: A case study of Xiaoerbulak Formation, Lower Cambrian, Aksu area, Tarim Basin, NW China. Petroleum Exploration and Development, 2017, 44(3): 349-358.
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2017, Vol. 44 
