Study Of Lacustrine Carbonate Reservoirs Of The Upper Es4 In Zhanche Sag

The lacustrine carbonate rock which is an important type of rocks in Jiyang depression has appeared great searching potential. Based on the data of core,well log and thin slice, this paper presents a study on the lacustrine carbonate rocks of the 4th member of the Eogene Shahejie Formation (Es4) in the western of Jiyang area, including the western of Zhanhua sag and the southern of Chezhen sag, by summarizing the tapes of lacustrine carbonate rocks, identifying the sedimentary facies, analyzing the tapes of reservoir spaces and diagenesis and reservoir characteristics, evaluating the reservoir and predicting the distribution of profitable reservoir.The lacustrine carbonate rocks of the studying area can be devided into three classes: limestone, dolomite and diamicitite. The limestone is the most important rock, including sandy limestone, micritic limestone and fram limestone. The dolomite distributing in limited area includes algal dolomite and micritic dolomite. The diamicitite distributing on the edge of the Zhanhua sag includes sandy limestone. The characterics of sedimentary facies in the studying area are as follow: the sedimentary facies in the northern of Chenjiazhuang hump from the edge to the center of sag are costal, shallow lake, semi‐deep lake and deep lake; but there is a modle of carbonate platform and bay in the eastern of Yihezhuang hump.There are three types of reservoir spaces: primary pore, secondary pore and fracture. Secondary pores are the most important reservoir space, while primary pores and fracture are secdonary ones. This study area has many diagenesises: compaction,cementation, filling,crossion, penecontemporaneous dolomitization, burail dolomitization, anhydritation and degypsification.We can classify the rocks into four classes: type I, type II, type III and type IV. Type I is the best reservoir forming in high energy environments such as bank and algal reef. Type II is the preferable one developing in the medium energy shoal environment, while type III is the poor reservoir and developes in the low energy inter‐bank environment. The worst one, type IV, developing in the extremely low energy mud flat, is the non‐reservoir.The cotrolling factors which can affect the quality of reservoir include rock types, sedimentary facies, diagenesis and tectonic movement. Rock types and sedimentary facies, the most important factors influenting the quality of rocks, greatly determained the quality of rocks. For example, the rocks with well‐developed primary porea such as frame limestone always have vast spaces. On the contrast, diagenesis and tectonic movement play a role in changing the quality of rocks.