关键词: 浊积扇, 沉积相, 沙河街组沙三上亚段, 商三区, 惠民凹陷

Abstract:

Da’anzhai member of Lower Jurassic Ziliujing Formation is one of the main oil-bearing reservoirs in Sichuan Basin. However, hydrocarbon exploration and development had little program in half a century because of the lack of knowledge about sedimentary facies and favorable reservoir distribution of Da’anzhai member. Taking Fuling demonstration area in eastern Chongqing as an example, based on the field outcrop measurement, description of drilling cores, thin sections, logging and tectonic-depositional backgrounds, it is considered that Da’anzhai member was deposited by lacustrine carbonates, which could be divided into half-deep to deep lake, lake slope, shallow carbonates, shallow terrigenous clastic lake and shore lake. According to the relationship between sub-micro facies and favorable reservoir development, the facies distribution of three sub-members in Da’anzhai member was compiled respectively. It is believed that the shelly beach edge and lake slope in lower first sub-member and upper second sub-member are the most favorable facies belts for reservoirs. The place above shelly beach edge and lake slope whose buried depth is 1 000～ 3 000 m, and the places where the regional tectonic stress concentrated and fractures developed, are predicted as sweet points for favorable unconventional reservoirs and shale gas reservoirs.

Key words: turbidite fan, sedimentary facies, upper submember o fEs₃, the third area of Shanghe Oilfield, Huimin Sag