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Sedimentary Characteristics And Research Of Source Rocks Of Upper Permian Linxi Formation In Xilinhaote-alukerqin Area, Inner Mongolia

Posted on:2013-12-01Degree:MasterType:Thesis
Country:ChinaCandidate:Y B QiuFull Text:PDF
GTID:2230330377450239Subject:Geology
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Songliao basin is a large petroliferous basin located in the northeast of China.With the deepening of exploitation, the composite water content of most oilfields inbasin has exceeded90%, and the recoverable reserves in the main producing oilstratum decreased gradually. So it is very important to explore the potential ofhydrocarbon resources in the deep and outside area of Songliao basin.On the basis of lots of field investigation, region data analysis and previousresearches, it was considered that in Xilinhaote-Alukerqin area, Inner Mongolia,which lies in the southwest of Xingan-Songnen massif and the north ofWenduermiao-Xar Moron River suture belt in the northeast tectonic belt, the darkargillite with huge thickness in Upper Permian Linxi Formation has favorablepotential capacity of hydrocarbon generation. Therefore, this article is mainly upheldby the theory of sedimentology, using the firsthand information which was obtainedfrom the sections measured in field survey as a foothold. And it was also based on theanalysis of petrology and sedimentary facies, using the single factor analysis andmultifactor comprehensive mapping method as its methodology, we we draw uplithofacies paleographic map of Upper Permian Linxi Formation inXilinhaote-Alukerqin area, Inner Mongolia, at a scale of1:500000. Combined withorganic geochemistry feature of source rock, we evaluate the hydrocarbon perspectivein this area. The main cognitions and conclusions of this thesis are as follows:1. Through comprehensive analysis of sedimentary facies on representative section,we detected four facies in Upper Permian Linxi Formation in Xilinhaote-Alukerqinarea, Inner Mongolia. They are carbonate platform,delta, shallow-marine shelf, deepwater basin. The carbonate platform facies can be further divided intoplatformmargin reef subfacies,platform foreslope subfacies,and platform-tidal flat subfacies.The delta faceis can be divided into three subfacies: predelta, delta front, delta plain,and can be further divided into several microfacies, such as distributary channel onwater, distributary channel under water, interdistributary bay, natural levee. Theshallow-marine shelf facies can be divided into two subfacies: shallow-water innershelf and deep-water outershelf,and can be further divided into several microfacies,such as low-lying land, sand bay. Through the two-dimension horizontal profile fromsouth to north, we can easily see that in the middle of this profile is deep-watersedimentation with petrography character of dark argillite with huge thickness. On thenorth of the deep-water basin is delta deposit, which can be divided into predelta,delta front, delta plain. On the south of the deep-water basin is shallow-marine shelfdeposit, which can be further divided into deep-water outershelf and shallow-waterinnershelf.2. Through synthesizing the analysis of representative section sedimentary facies, thecharacteristic analysis of two-dimension distribution of sedimentary facies, thecharacteristic analysis of plane distribution of lithofacies, and the characteristicanalysis of plane distribution of Sand shale ratio, we divide Upper Permian LinxiFormation in Xilinhaote-Alukerqin area, Inner Mongolia, into five facie regions,including the carbonate platform in the Xilinhaote area in the west part, the carbonateplatform in the Alukerqin area in the east part, the delta facies in the Xi UjimqinBanner in the north part, the deepwater basin in the middle part, and theshallow-marine shelf in the south part. The palaeogeographic framework of UpperPermian Linxi Formation in Xilinhaote-Alukerqin area, Inner Mongolia, shows thedistribution feature that the north and south are shallow and the middle part is deep,the east and west parts are carbonate platforms. The deep-water basin in front of deltafront is the potential location of hydrocarbon generating sag, and the sand bodies inbranch channels and mouth bar of delta facies is the great potential reservoir bed.3. The source rocks in study area are mainly dark argillites, and the source rocks withthe lithology of dark argillites distribute widely in study area. The distribution ofthickness has some limitation, but the distribution on plane is very huge. Comparedwith the source rocks of different sections, no matter the dark argillites or limestones,their spatial distribution varies apparently, and the rate of source rocks/stratum in asection ranges from76.33%to1.71%. The study on organic geochemistry shows thatthe content of organic carbon in section GD arrives at the lower limit of normal source rock, and part of them arrives at moderate criterion of normal source rock; thecontent of organic carbon in section TB arrives at moderate criterion of normal sourcerock, and part of them arrives at better criterion of normal source rock. The study onthermal decomposition of source rock reveals that the Tmax in section GD shows thematurity has arrived at the stage of mature-highly mature. The Tmax in section TBshows the maturity has all arrived at the stage of highly mature. The maturity ofsource rock of Linxi Formation in study area varies apparently on horizontaldistribution. The carbonaceous slates in section ZE show the overmaturecharacteristic, but varies apparently on horizontal distribution. It is estimated thatmagmatic activity led to these results.4. The hydrocarbon generation depression of Linxi Formation in study area mainlylocated in the deep-water basin and the predelta and deep-water shelf in themiddle-southwest part. In this area, the content and maturity of organic carbon arerelatively ideal, so this area is a preferable potential region of source rock. Moreover,the dark fine grained clastic rocks with huge thickness are widely distributed, whichoffer the lithologic foundation for source, reservoir, cap of shale gas. Upper PermianLinxi Formation in Xilinhaote-Alukerqin area, Inner Mongolia has huge potential ofnon-conventional oil/gas resource, especially shale gas resource, except for somepotential of conventional oil/gas resource. So it is an important petroliferous areareplacing the Songliao basion.
Keywords/Search Tags:Northeastern Inner, Mongolia Upper Permian, Linxi Formationlithofacies palaeogeography, source rock shale gas
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