The Hydrocarbon-generation Potential Evaluation In Majiagou Group Of Ordos Basin

In this paper, we take the carbonatite in Majiagou Formation as an object of study. Byanalyzing the schlolar’s viewpoints,Based on the comprehensive analysis of characteristics ofsource rock,such as abundance of organic matter, threshold value of organic enrichment andHydrocarbon-generation potential，we collected logdate,logging,core analysis date and otherbasic geological data in the area of research,utilized the principle and methods ofsedmentology,organic geochemistry to build a simulation model to estimates ofhydrocarbon-generation potential. The main research results of papers obtained as follows:1.Lithology in Ordos Basin are dominated with low argillaceous source.The kerogen typeis predominantly sapropelic and evolution of source rock is durning the high-and post-maturestage,abundance of organic matter belong to poor to middle grading.2. Residual abundance of organic carbonatite in Majiagou Formation mainly in southwestOrdos basin and platform slope facies, the Residual organic matter abundance is mainlydistributed in the range of0.30%to0.40%, followed North-east central paleo-uplift,theabundance from0.25%to0.30%, the residual abundance of organic carbonate of platformclose to the eastern central paleo-uplift is general and inferior,most is0.20%to0.30%.3. overall evaluations of carbonate source rocks made by Hydrocarbon expulsion,Abundance of Residual organic carbon, Carbonate reservoirs. the minimal value of organicabundance of carbonate source rocks could be assigned by2.5%. The thickness distribution ofwestern Majiagou Formation oriented into a north-south disposition. Along centralpaleo-uplift west slope, thickness increased gradually from east to west. The carbonate inMajiagou Formation, which was developed in south of basin, formed in e-w trending. Alongsouth of central paleo-uplift, thickness increased gradually from north to south and changedgreatly in the plane. The abundance of organic matter in different facie belt in MajiagouFormation had great difference in longitudinal distribution. Epiplatform slope, evaporationplatform and gypsum rocks depression were relatively superior among them.4.The cumulative generated hydrocarbon quantity was50.93,67.70,53.77billion squarein northern part of western margin, western margin belt, Weibei uplift in research area. Thecumulative hydrocarbon gene-(ration) intensity approximated to15～20m3/km2,20～25 m3/km2,25～30m3/km2respectively. The main generation period was from Late Triassic toLate Cretaceous. Source rock was mainly distributed in the region of north part of westernmargin and south margin and sparse in northeastern. As generated hydrocarbon quantity ofdark shale in Majiagou Formation was far less than carbonate, it was hardly influence on eachregion’s evaluation in Majiagou Formation.