Characteristics And Main Controlling Factors Of Karst Reservoirs In Changxing Formation Of Gaoshi Ladder-Hot Packing Field

Previous studies is generally believed that the sichuan basin to the set of feixianguan changxing formation is a continuous deposition interface,howerver,the appearance of a large amount of drill vent as well as a lot of karren, soluble seam, karst cave and karst breccia can be observed on the core based on detailed field outcrop observation and drilling, logging and core data analysis, etc. hence there are the sedimentary discontinuity during Changxing stage to Feixianguan stage and formed top palaeokarst unconformity of Changxing formation according to the comprehensive analysis of data.lt is believed that a grand regression at the end of the Permian which causing a long exposition play a major role of palaeokarst of Changxing formation in the region of interest. Palaeokarst zone have strong capacity of optimization for carbonate reservoir performance, also the palaeokarst unconformity surface can be used as the high quality of long distance oil and gas migration channel.and karst slope zone is favorable zones for oil and gas accumulation indeed. On the premise of accurately explain the Changxing formation lithology researching Changxing formation's strati graphic division and correlation closer to isochronous interface in study ingdistrict with the guidance of carbonate petrology, stratigraphy, the theory and methods of carbonate sedimentology and other disciplines through mastery and digestion of the existing research results.and put forward the in the research district the Changxing formation has the dichotomy and the northeast and the southwest lithologic difference is obvious. Combined with the microscopic chip at the same time, a systematic research in Changxing formation's rock microfacies types, clarify the reservoir of changxing group in the study basic characteristics, types and characteristics of diagenesis, exploring the fundamental reason for the control of reservoir permeability distribution. Through the research above.we think Changxing formation is given priority to with platform-margin beach and interbank sea sedimentary facies in the study area,mainly for the carbonate deposits and shale content is relatively small, vulnerable to exposure of dissolution and controlled by landform. and combined with well logging, seismic data to recover the changxing's palaeogeomorphology, divided it into karst highland, karst monadnock and karst depressions, puts forward a the reservoir geological predicting model, and finally deducing the distribution of favorable reservoir zones.