Study Of Different Kinds Of Organic Source Of Meso-Neoproterozoic To Lower Palaeozoic Strata Of China

The successful exploration of several buried hill reservoir in Mesoproterozoic strata of North China Craton,An Yue gas field in Sinian-Lower Palaeozoic strata of Yangtze Craton and sub-salt oil-gas found in Cambrian strata of Tarim basin have all verified the great potential for hydrocarbon exploration of Meso-Neoproterozoic and Lower Palaeozoic strata in China.As an important control factor to source rock‘s tendency to oil or gas,main organic source of Meso-Neoproterozoic and Lower Palaeozoic strata is still unclear.To confirm organic source of antiquity source rock,this thesis choose samples from Mesoproterozoic Xiamaling formation and Lower palaeozoic Niutitang formation,precisely manipulate the source rocks to gain free organic matter from source rock,and using gold tube pyrolysis experiment and RICO experiment to gain bound organic matter in kerogen from source rock samples,using GC-MS technique to analyse biomarkers in different states of organic matter and study organic source of Meso-Neoproterozoic and Lower Palaezoic source rock in China.The thesis concludes as below:(1)Biomarkers distribution of bitumen “A” extracted from Xiamaling samples indicating that prokaryote species contributites the main part of organic matter in Meso-Neoproterozoic strata,and some prokaryotes that only exist in Proterozoic also contributes part of organic matter.Sterane is absent in all samples analysed,contuibution of eukaryote needs to be analysed based on biomarkers both in Bitumen “A” and from kerogen.Sterane/hopane ratio of Niutitang Bitumen “A” is 0.49 on average,indicating eukaryote like alga had become an important source of organic matter in Lower Palaezoic strata;Sedimentary environment of Niutitang formation changed organic species and organic source in different degree.(2)Difference between element concentration and liquid hydrocarbon yield of different kerogen indicate that preserve condition of organic matter influences source rock‘s oil-bearing potential,anaerobic environment is beneficial to the preservation of organic matter,and in turn become source rock with better oil-bearing potential.(3)Production of all different degradation modes show a characteristic of low biomarker concentration,production of RICO reaction can hardly detect any steranoic or hopanoic acid methyl ester.Biomarker distribution of production of kerogen pyrolysis indicates that source of bound organic matter is mainly prokaryote,but distribution of hopane differs from that of bitumen “A”,part of bacteria participated in secondary action didn‘t bound onto kerogen macro molecule or just bound onto the out part of molecule and cleavage into hydrocarbon in the low pyrolysis temperature stage.Sterane is detected in pyrolysis production,indicating organic matter exists eukaryote contribute,but it contains just a small part,prokaryote plays a dominant role in Mesoprotrozoic biological species.In summary,prokaryote like bacteria is the primary component of organic source in Mesoproterozoic Xiamaling formation,eukaryote also contributes,but it just contains a small part.Till Lower Palaeozoic period,biological evolution degree is significantly promoted,evolution of alge had reached a much more prosperous level,becoming an important part of biological source.In addition,species in different kind,different period preserve and turns in different ways,they bound onto different part of kerogen,and some may turns into liquid hydrocarbon in a way similar to immature oil.