Hydrocarbon Geochemical Characteristics And Accumulation In The Eastern Junggar Basin

There are many sets of source rocks and reservoirs in the eastern Junggar Basin,with abundant resources.Aiming at problems of unclear oil source and accumulation process,this paper will study the characteristics of reservoirs,oil-source comparison and the relationship between source kitchens and reservoirs,which has guiding significance for exploration and development in this area.By combining the geochemical characteristics of the source rocks and the sedimentary environment to classify the organic facies,predicting the fluid properties can be realized,which is of great significance for the study of the accumulation process.The results show that the main part of oil is mature,among which there are low-mature oil accumulation in Shabei area.The organic source of oil is mainly lacustrine algae and aquatic plants,and the deposition environment is a reducing environment,which is conducive to the preservation of organic matter.The oil in Sha'nan,Santai and Beisantai oil fields comes from Permian source rocks,the low mature oil in Shabei area comes from Jurassic source rocks,and the oil from Cainan oil field comes from a mixed source of three sets of source rocks.The Permian source rocks are dominated by the C phase,and the oil discharge intensity can reach 120 mmbbl/km~2;the Triassic and Jurassic are dominated by the D/E and F phases.Gas is mainly produced from Jurassic F phase coal rocks,with an exhaust gas intensity of 6 million cubic meters/km~2,and some oil-type gas generated from mature phase C source rocks.The oil and gas generated in the Fukang sag migrated and formed reservoirs over long distances through fault and unconformity.There is near-source reservoir formation in Beisantai oilfield.The distribution and accumulation of oil and gas were consistent with the principle of differential accumulation,low mature oil produced in the source rock in the early stage moved to farther traps,and the mature oil and gas produced in the later stage move into the close traps.