Characteristic Analysis Of Mesozoic-paleozoic Reservoir In Subei Basin

Subei Basin is located in the Tianchang region that is in northern ofJiangsu province and eastern of Anhui province，its structure belongs to LowerYangtze plate, which is a Mesozoic-Cenozoic basin based on Yizhengmovement of Late Yanshan Epoch. This paper studies Subei Basin includingSubei Cenozoic basin and Sunan area, it develops huge thickness marinecarbonate rock and clastic rock stratum in Mesozoic-Paleozoic, and in Jurong、Huangqiao and other places have good oil and gas shows.The pioneers aiming at the research on the Mesozoic-Paleozoic reservoirbodies in Subei basin marine faces mainly uses Basin internal drilling cores,well-logging and earthquake information, less research for the outcropproperty of oil and gas bearing stratum around the basin, lack of thecomparison between the reservoir property of outcrop region and the reservoirbodies data inside the basin. Meanwhile, since this region undergoing intensetectonic action, makes the reservoir’s distribution rule in vertical and horizontal,structure characteristic and planar spreading of sedimentation environment etc.characteristics less clear, especially in Huangqiao and Jurong, researchcontent is basically concentrated on the Permain and Triassic reservoir bodieswhich are shallow buried in this area, aiming at the comparison of lengthwaysstratum property in Paleozoic-Mesozoic is less.This paper mainly combined the field geological investigation, measuringwith the drilling and logging data in Subei Basin, develop studying thePaleozoic-Mesozoic reservoir characteristics in Subei Basin, analysis thediagenesis, dissolved pore and cave development, structural fracture andsedimentary facing reservoir affection. Conclude study area favorablereservoir distribution rule in Mesozoic-Paleozoic, summarize the oil and gasspreading characteristics and then to divide the favorable exploration area.Among, field geological investigation includes24site investigation andobservation of the typical outcrop section,233collect samples,913fieldgeological photos.82thin slice making,200microscopic photos,27reservoirphysical property testing. Collected data include11Jiangsu Provincegeological research reports,8logging data, and more than100relatedliteratures.Through the research, this paper mainly obtains the following understanding and achievement:(1) The Mesozoic-Paleozoic reservoir body in Subei basin totality showscharacteristics of low porosity and low permeability, inside of these, thephysical property of Devonian Wutong group and Permian Longtan groupdeveloping the clastic rock reservoir are relatively well, and then are thecarbonate rock reservoir of the Permian Qixia group and Triassic Qinglonggroup.(2) Diagenesis and precipitation facie are main controlling factors of studyarea reservoir developing. Paleozoic-Mesozoic diagenesis of study areamainly includes the compaction, pressolution, cementation, recrystallizationand so on; in carbonate rock reservoir body, cracks, pores, caves are the mostimportant influencing factors, they improve the reservoir property of the lowporosity、low permeability and super low porosity reservoir bodies. Thesereservoir bodies are low porosity and low permeability or super-low porosityand super-low permeability. Through compare and analysis the precipitationfacies in Huangqiao and Jurong, think fluvial facies、 platformal trough、deltaand deep water continental shelf facies in this area as high–quality reservoirbodies.(3) Through the comparative analysis of reservoir characteristics, structurefactors, sedimentary facies, the high-quality reservoir body appears NEbanded distribution, on the basis of this, the favorable oil and gas explorationarea are divided.Subei Basin and South Yellow Sea Basin are the same tectonic unit inMesozoic-Paleozoic Period. South Yellow Sea Basin has prospected fordecades, but there has been no breakthrough in oil and gas in the SouthYellow Sea basin for Paleozoic-Mesozoic Period. So through analysis andstudy the reservoir characteristics and regularity of Paleozoic-Mesozoic inSubei Basin, provide some reference for oil and gas prospecting of SouthYellow Sea Basin.