The Characteristics Of Source Rocks And The Kitchen-Reservior Correlation In The Southern Margin Of Junggar Basin

In this paper,an integration of organic geochemistry,organic petrology and quantitative analysis of oil-gas systems is applied to analyze the organic facies and hydrocarbon source kitchen of the key source rocks(E_2-3a and J₁₊₂)in the southern margin of Junggar Basin.Firstly,the spatial distribution of different organic phases in source rocks,thermal evolution characteristics and quantitative evaluation of source rocks are investigated.Secondly,the hydrocarbon properties of the discovered reservoirs and the characteristics of source kitchen are compared and analyzed.Thirdly,the kitchen-reservior correlation has been revealed.Results show that the E_2-3a lacuvial argilaceous source rocks are mainly D/E and Cf facies,which are distributed in the Horgos region in the middle of the study area.The thickness of E_2-3a source rocks decreased significantly from east to Hutubi and west to the Sankeshu Depression.Currently,the source rocks are in the immature to low-mature stage,and the hydrocarbon supply capacity is limited.The J₁₊₂ coal-measures source rocks are widely distributed in the study area,and in the marginal belt are mainly F facies and a few D/E facies.In addition,it is speculated that the D/E facies source rocks are developed in the center of the depressions based on the hydrocarbon properties.The maturity evolutions of the source rocks are different in the east and west of the study area.The J₁₊₂ in the eastern Hutubi area entered the hydrocarbon generation threshold in the middle Jurassic(?164 Ma)and is currently at the peak of gas generation stage.However,the J₁₊₂ source rocks in the western Sikeshu Depression entered the hydrocarbon generation threshold in the middle Early Cretaceous(?110 Ma)and is currently at the peak of oil-generation.The study area presents the oil-gas phase distribution pattern of“west oil east gas”,and the hydrocarbons in the western part are mainly the light humic oils,which are mainly the products of the J₁₊₂ source rocks in the mature stage.However,the hydrocarbons in the eastern part are mainly coal-derived gases,which are mainly generated by the J₁₊₂source rocks in the high maturity stage.The maturity characteristics and organic facies distribution of the J₁₊₂ source rocks together control the oil-gas phase distribution pattern in the study area.In addition,the source kitchen is also controls the spatial distribution of oil and gas to some extent.