Genesis and evolution of Lower Cambrian Longwangmiao Formation reservoirs, Sichuan Basin, SW China

oleh: Jingao ZHOU, Chunchun XU, Genshun YAO, Guang YANG, Jianyong ZHANG, Yi HAO, Fang WANG, Liyin PAN, Mingfeng GU, Wenzheng LI

Format: Article
Diterbitkan: KeAi Communications Co., Ltd. 2015-04-01

Deskripsi

Based on observation of outcrops, cores and thin sections and analysis of logging data and experiment, the features, main controlling factors, evolution and distribution of the Longwangmiao Formation reservoirs in the Lower Cambrian, Sichuan Basin, are examined carefully and the distribution of favorable reservoirs is predicted. Mostly fracture-pore type, the Longwangmiao Formation reservoirs are dominantly comprised of residual dolarenite, oolitic dolomite and crystal dolomite, with dissolution cavities and dissolution pores as the main storage space, an average porosity of 4.28%, and average reservoir thickness of 36 m. The formation of the reservoirs is controlled by grain shoal facies, parasyngenetic dissolution and parasyngenetic dolomitization. The reservoirs have experienced four evolution stages, the period of pore formation laid the foundation for storage space types and physical conditions of the reservoirs; the reservoir physical properties were improved further in the hypergene karstification period; the porosities were decreased by minerals filling during the hydrothermal period; and the reservoirs became denser in the burial dissolution and asphaltic filling period. Based on the main controlling factors of Longwangmiao reservoirs, the high geomorphology area between Huayingshan fault and Longquanshan fault is predicted as the most favorable reservoir zone. Exploration breakthroughs will possibly be made in Guang'an-Nanchong-Jiange area. Key words: Sichuan Basin, Lower Cambrian Longwangmiao Formation, reservoir type, reservoir controlling factor, reservoir evolution mode, reservoir prediction