The Characteristics And Comprehensive Evaluation Of Petroleum Geology Of Upper Palaeozoic In The Southern Songliao Basin

In the late early Paleozoic the Songliao region was completely joined with Ergun massif,Xingan-songnen massif,Jiamusi massif together to form a unified Jiameng massif,at same time started overlying stratal evolution stages from late Paleozoic.Due to locate on two tectonic units South Rim of Jiameng Massif and northern margin of North China,late Paleozoic sedimentary characteristics of south Songliao basin is a typical continental margin.Based on field observation and well drill research in the south of Songnan region,the sequence of late Paleozoic strata in the northern region of southern Songliao basin has been established.The Carboniferous-Permian in the northern margin of North China developed well,mainly Littoral facies deposit,parts of the transition for marine-terrigenous facies sediments.Evidences from comparison stratigraphic with sedimentary features,distribution of lithologic,stratigraphic chronology,gravity and magnetic and electric data,and regional seismic data interpretation confirmed basically that changling area without large scale metamorphic crystalline basement presumably belongs to the Jiameng massif;basement properties of Lishu region belongs to the northern margin of North China plate.So the xilamulunhe suture which is borders in the northern margin of North China is located in the songliao basin.In this area tectonic deformation of the Paleozoic is complex,which showed as a series of imbricated thrust nappe structure features with characteristic of orogenic belt,but later its erosion transformation is serious,dominated by large overthrust nappe structure and its bottom extends to deep above the detachment surface.Interpretation of seismic data and drilling data analysis showed that the distribution of Upper Paleozoic strata in songnan area is feature of the north-south zonation and east-west block,by Xilamulunhe suture zone and chifeng-kaiyuan fault zone as the boundary of Upper Paleozoic in the region can be divided into northern,central,and southern zone.In the central zone(between Xilamulunhe suture belt in the northern margin of North China and Chifeng-Kaiyuan fault zone),late Paleozoic such as Carboniferous,Permian and Paleozoic strata are mainly located in the Western zone,middle-upper Proterozoic magmatic rocks are concentrated Lishu areas in Eastern.In the south zone(South of Chifeng-Kaiyuan fault within the North China)there are mostly Archean and Proterozoic bedrock,the Paleozoic strata distribute in parts of the Eastern.Permo-carboniferous in the study area development of multiple sets of hydrocarbon source rock,especially,in the muddy hydrocarbon source rocks in middle and upper Permian,its plane distribution by the Xilamulunhe suture zone reveal characteristics of the north-south zonation and east-west block.The region with high organic matter and low thermal evolution has high hydrocarbon potential.Muddy hydrocarbon source rocks have the characteristics of high abundance of organic matter,high thermal evolution degree,its organic matter type given priority to with ? type,mixed with some ?.Through hydrocarbon generation simulation with the thickness of hydrocarbon source rocks,upper palaeozoic data,organic carbon abundance data and organic matter maturity,the comprehensive calculation of hydrocarbon generation,upper palaeozoic nature gas total is 328 trillion m3,and selecting reasonable expulsion-accumulation coefficient coefficient,the resource is 0.984 trillion m3.According to reservoir conditions of the permo-carboniferous sandstone and carbonate rock and mainly pelite cap rock in the upper Paleozoic of south of Songliao Basin there existed the form of the main source rock,reservoir and cap rock composition of self-source rock and self-reservoir,lower source rock and upper reservoir and new source rock and old reservoir types.Comprehensively Based on thick upper palaeozoic formation,abundant hydrocarbon source rock,shallow top of the buried depth,moderate organic matter maturity,a certain hydrocarbon-generating potential,relatively stable structure,relatively intact,the late deeply burial,multi-type favorable reservoir-cap combination and so on to qualitatively evaluate,two favorable exploration zones are comprehensively optimized in upper palaeozoic south Songliao Basin respectively Manghan and changtu-Lishu sags.