Study Of Hydrocarbon Source Characteristics Of The Late Paleozoic To Cenozoic Strata In The North Of Beibu Gulf, Guangxi

Guangxi Beibu Gulf is a Cenozoic sedimentary basin,its basin basement is Lower Paleozoic metamorphic rock.Basin is located in the southern margin of the Eurasian Plate,where the combinate zone between Yangtze Plate and Cathaysian Plate.It is blongs to the transitional crust,Paleogene is the main period.The basin basement is Metamorphic rock of Lower Paleozoic,Upper Paleozoic developed a set of marine carbonate.Mesozoic is mainly the uplift anderosion,at the last phase of Yanshan movement,extension tectonics formed the faulted basin.Study area is in the northern margin of the North Bay,the west is the border of China and Vietnam,the east is the common border of Guangdong and Guangxi,the north is nanning,the south is shoreline.With the development of resources in the economic zone of Guangxi North Bay,the oil and gas exploration in North Bay Basin draw more attention.But on the whole, the research degree is relatively low and one-sided,oil and gas resources need further exploration and development.This article is based on the analysis of previous research data, combined with field geological measured profiles to prospecting and sampling and the collect samples are used for indoor geochemical technical analysis,the distribution feature^ organic carbon content、Rock-Eval analysis、chloroform bitumen "A"、maceral analysis、vitrinite reflectance、stable carbon isotope、physical properties analysis、 cast image analysis and biomarker etc. of late Paleozoic-Cenozoic source rocks in the northern margin of the North Bay, Guangxi are analyzed comprehensively. On this basis, the evaluation of source rocks in the study area,providing the basis for a comprehensive understanding of the oil and gas resource potential in North Bay Basin,providing the geological basis for the next step in deep verification.Paper made the following major awareness:1.The northern margin of the northern Gulf of Guangxi late Paleozoic-Cenozoic sedimentary strata of great thickness,the major types of source are marine rocks carbonate rock and lacustrine clastic rocks,and high content of organic matter in marine carbonate rocks.Terrigenouslacustrine source rock is the dark mudstone, coal and mudstone, mainly distributed in the thirdstrata In the study of 165 samples of organic carbon content in average was 0.41%,the maximum value is 5.26%,and the minimum value 0.001%,with inhomogenerous distribution Luolouof three Triassic, Heshan formation of two Permian,Temple group goldgroup and the British Tang Group of lower Carboniferous,and mud the Devonian etoucun FM are good hydrocarbon source rocks.The type of organic matter belongs to the type I and type II, which was derived from lower marineplankton and algae; thermal evolution of organic matter mostly inamaturestage, only the Heshan formation and in Nanan sectionof luolou limestone immature to highmaturestage.The reading source rocks is a very good sourcerocks, with high content of organic matter.the maximum value reached 14.82%,and the average value of 4.04%;the type of orgnic matter belongs to organic type I and type III;The evolution of organic matter in the immature stage.Ro of the 11 samples,to a maximum of 0.41%,while the minimum is 0.37%,and the average value is 0.40%,with good hydrocarbon potential.2.Using conventional biomarker compound parameters jude organic matter source and sedimentary environment: ①The organic matters in source rocks of Changdun profile and Fulong profile in the Paleogene Nadu formation are reducing transitional environment,which mainly a mixed source of aquatic organisms and terrigenous higher plants; Si Tang Mei Kuang and Nianziping is partial oxidation sedimentary environment, which mainly comes from terrigenous organisms.②In the late Paleozoic-Mesozoic strata, the source material of Luolou Formation of Triassic and Qixia Formation and Heshan Formation of Permian is mainly algae. The source material of Nanhong Formation of Triassic is mainly lower hydrobiont,whose depositional environment is weakly reduction-oxidation environment.The source material of Simen Formation and Yingtang Formation of Carboniferous terrigenous higher plants.Dun to the high organic matter evolution degree Etoucun Formation of Upper Devonian only could not judge its source matter from the spectra. Because the organic matters of the Late Paleozoic-Mesozoic strata are mostly at the high mature stage,it makes no sense that using biomarkers compound parameters of sterane and terpane jude organic matter source and sedimentary environment3.There are 3 major hydrocarbon generation intervals,the first one is the reading group(E2n), Hydrocarbon generation products give priority to biological methane gas, immature oil and condensate oil.the second one is Heshan formation of two Permian, with High maturity of light oil, condensate oil and moisture,the last one is Lower carboniferous temple door group (C1S), gold (C1h), ying tang group (C1yt) and on the forehead of the devonian system schiscosomiasis interval (D3et) is a combination.4.Oil and gas exploration targets in the northern Gulf of Guangxi to the third strata, theformation of organic matter in the immature and low mature stage, is the formation of oil (orgas) to aggregate to form deposit.