Tight Oil Accumulation Conditions And Favorable Areas Optimization Of The Upper Permian Leping Formation In The East Of Nanpoyang Faulted Basin

According to the 2D seismic geophysical data,utilizing the Yifeng-Jingdezhen fault,Fengcheng-Wuyuan fault,Shuanggang-Ruihong fault and Junshan-Sanhu fault as the boundary,the Nanpoyang faulted basin can be from north to south divided into Kangshan depression,Ruihong uplift and Erjiacun depression three tectonic units.Due to the abundant seismic and drilling datum,the Erjiacun depression can be further divided into Letan 1 north structural belt,Letan 1 structural belt and Mingjian 1 structural belt.Through regional geological survey and drilling datum,the sedimentary characteristics of the Leping formation in the study area have been preliminarily identified.Leping formation is mainly formed in the transitional facies sedimentary environment.Wangpanli member deposited deposited coal fine sandstone,siltstone and mudstone in the tide flat environment.Shizishan member deposited fine-sandstone and mudstone in the barrier island environment.Laoshan member deposited sandstone and mudstone bearing coal,in the shelf and tidal flat facies.Guanshan member deposited meandering river facies sand stone and shore facies sandstone and mudstone.Through the experimental analysis,it is concluded that the main source rocks in Leping formation are lower Laoshan member coal and mudstone and upper Guanshan mudstone.The Laoshan mudstone thickness is 52.30 m,with TOC between 0.26~2.1%(average:0.96%);B3 coal seam thickness is about 3m,with TOC between 61.25~ 81.84%(average:71.67%),possessing strong ability of generating oil;Guan Shan mudstone thickness is 31.61 m,with TOC between 0.16~13.95%(average:2.50%).The thermal evolution of the Leping Formation in the study area ranges from 0.68% to 1.34%,which means the mature stage and the oil is the main production.The main reservoir is the tight sandstone in the upper Guan Shan member,with a thickness of 32.64 m and a porosity of 4.69~15.95%(average : 10.33%).Based on the Well Leye 1,there are 7 layers oil shows amount to 13.55 m in the upper Guanshan member tight sandstone.It is concluded by comprehensive analysis that Guanshan member sandstone obtains abundant oil shows not only due to its favorable reservoir properties but also because of the superior source rocks above and below.The accumulation model can be summarized “two sources placing one reservoir in between ”.Based on the comprehensive geological background,tight oil accumulation conditions and data richness degree,the favorable area for tight oil accumulation in the study area is selected.Erjiacun depression and Ruihong uplift are evaluated and optimized,which are the favorable areas and prospective areas for tight oil accumulation respectively.