Diagenesis and porosity evolution of the Ordovician in sub-salt area, Tahe Oilfields
Zhang Demin1, Bao Zhidong1, Li Guorong2, Hao Yan3
1. College of Geosciences, China University of Petroleum(Beijing), Beijing 102249;
2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059;
3. Sinopec Overseas Oil & Gas Ltd. (Babon Branch), Beijing 100083
Based on the observation of 55 cores and 300 thin sections and combined with the geochemical data, the diagenesis and porosity evolution of the study area were analyzed systematically.The types of diagenesis include cementation,karstification, pressolution, silicatization, cataclasis, dolomitisation, recrystallization. The karstification can be divided into four stages:Syngenetic stage,Middle Caledonian stage,Early Hercynian and Late Hercynian.And the karstification of Middle Caledonian stage and Early Hercynian are vital to the reservoir development.On the above results,the diagenesis and porosity evolution were analyzed.