烃源岩生排烃动力学研究——以惠民凹陷临南洼陷沙河街组烃源岩为例

Petroleum Generation and Expulsion Kinetics:A Case Study of the Sahejie Formation Source Rocks from Linnan Sag of Huimin Depression

本研究以惠民凹陷临南洼陷沙河街组为例,应用GOR—Evaluation模拟软件,提出了以动力学为基础、定量评价烃源岩生排烃历史的方法。该方法的要点在于:应用黄金管—高压釜限定体系热模拟实验装置,研究典型烃源岩生烃动力学参数;结合临南洼陷烃源岩EOM/TOC—-深度剖面,模拟计算烃源岩开始排烃时的烃产率(Hpm);通过分析烃源岩地球化学资料,进行烃源岩分类、建立生排烃模拟的综合地球化学参数。应用该方法研究了临南洼陷Es31暗色泥岩、Es23-3暗色泥岩与暗色页岩的生排烃特征。研究结果表明:临南洼陷Es32-3暗色页岩与暗色泥岩Hpm值分别为150mg/g与170mg/g;临南洼陷X101井Es32-3暗色页岩、Es32-3暗色泥岩及Es31底暗色泥岩生油门限分别出现在20Ma、13Ma与19Ma,排油门限分别出现在10Ma、8Ma及2Ma。这三类烃源岩的生烃门限对应EasyRo在0.55%左右,但他们的排油门限存在明显的差别,EasyRo变化范围0.61%～0.69%。该研究方法的优点在于,将实验数据模拟与实际地球化学资料相结合,避免了复杂排烃参数的设定与排烃机理的解释,研究结果可应用于烃源岩生排烃定量评价、有效烃源岩圈定及油气资源量预测等方面。

This paper has introduced an approach which is based on the kinitics method and the software GOR-Evaluation for quantitative assessment of petroleum generation and expulsion of source rocks through a case study of Sahejie Formation of Linnan sag, Huimin Depression. The key points of the present approach include ： an investigation of petroleum generation kinetics parameters of typical source rocks based on their thermal pyrolysis data carried out in a gold tube-autoclave; an investigation of the petroleum generation amount （Hpm） when oil begins to be expulsed from its source rock by combining the modeling results with the plot of EOM/TOC-depth of the source rocks from the Lin-nan sag; and an establishment of representative geochemical parameters of different types of source rocks by analyzing the available geochemical data. The petroleum generation and expulsion history of the three sets of source rocks from the Linnan Sag （Es~ dark mudstone, Es^-3 dark mudstone and Es3^2-3 dark shale） were investigated by this approach. The results have shown that the Hpm values of the Es3^2-3 dark shale and the Es^-3 dark mudstone are 150 mg/g 与170 mg/g, respectively. The oil threshed and oil expulsion threshed of the Es3^2-3 dark shale from the Well X101 occurred a： 20 Ma and 13Ma; the Es3^2-3 dark mudstone at 19 Ma and 10 Ma; and the Es3^1 dark mudstone at 8 M and 2 Ma, respectively. The oil generation threshed of the three types of source rocks all occurs at about 0.55% of Easy Ro, but their oil expulsion threshed varies extensively, from 0.61% to 0.69% of EasyRo. It is believed that the merits of the present approach lie in that it avoids enactment of complicated oil expulsion parameters and explanation for oil expulsion mechanism and the results can be applied to quantitative assessment of petroleum generation and expulsion of source rocks, determination of effective source rocks and prediction of petroleum resources.