| Based on the time-temperature compensation theory of Tissot,we select two samples,the black brown shale of upper Triassic Yanchang Formation Chang 7 in Ordos basin(Type-?lacustrine source rocks)and the black siliceous shale of Permian Dalong formation in Sichuan basin(Type-?marine source rocks),as the experimental objects.Using the direct-pressure hydrocarbon generation and expulsion thermal simulation system,the rocks'hydrocarbon generation and expulsion process were simulated under the conditions of overlying strata pressure,fluid pressure and heat effect.Through quantitative analysis,thermal maturity calibration and losing light hydrocarbon recovery,we can discuss the hydrocarbon generation potential and the expulsion efficiency of type-?organic matter,then we evaluate the resource potential of actual formation by this method.The results show that:1)The hydrocarbon generation and expulsion process of type-?organic matter can be divided into three stages,where Ro is 1.0%and 1.3%for segmentation nodes.The total hydrocarbon yield shows rapidly rising in the first stage,the second stage stable growth,and the third keeps stable;the hydrocarbon expulsion efficiency shows slower growth in the first phase,the second is rapid growth and the third tends to be stable trend.The hydrocarbon expulsion efficiency in oil generation peak is below 70%,which belongs to the moderate hydrocarbon expulsion,and quickly reaches more than80%in the end(Ro>1.3%).2)Under the same experimental conditions,experimental temperature and experimental Ro of different types of samples are uniform,and the length of constant temperature has a significant relationship with the nature evolution.Under laboratory conditions,the relationship between the H/C and temperature can be grouped obviously,which is controlled by the types of organic matter but sedimentary facies is independent.The measured Ro of type I and II organic matter samples is higher than the natural geological evolution profile.Therefore this method is feasible and more direct.3)With the increasement of the experimental temperature and the maturity,the content of the light hydrocarbon in type-?organic matter is gradually increasing.The problem of the calculated light hydrocarbon is one of the reasons leading the high efficiency of hydrocarbon generation.When Ro is below 1.0%,the content of light hydrocarbon is low,which is about 11%of the total content;but after Ro is increasing to 1.3%,the content is significantly increased with the light hydrocarbon content of Ordos Basin close to 50%and the Sichuan Basin more than 57%.In the process of product measurement,the losing amount of light hydrocarbon is much more,which affects the evaluation of hydrocarbon expulsion efficiency and hydrocarbon generation potential.4)The characteristics of hydrocarbon generation and expulsion of the same kerogen types have little difference and sedimentary environment has no obvious effect to it.The hydrocarbon expulsion efficiency of upper Triassic Yanchang formation Chang 7 in Ordos basin is lower than Permian Dalong formation in Sichuan basin,while the total hydrocarbon content of Chang 7 is higher,which could have some relationship with the organic matter abundance,the rock physical property,the hydrocarbon generating pressurization and the random error of the experiment etc..5)The hydrocarbon intensity estimation of Ordos basin Yanlong 7 shows that the main distribution of hydrocarbon is in Jiyuan-Huanxian and Huachi-Taerwan and the distribution range is large,but the expulsion hydrocarbon efficiency is low.The potential of dense oil and tight gas is respectively 4×10~8t and 1.4×10~8t,and the shale oil is 2.5×10~8t.Because of the different types of the organic matter,Chang 7 member has the advantage in thickness than the type-I source rock in Bakken,Williston Basin,and the dense oil resource is very rich. |
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