两种温压体系下烃源岩生烃演化特征对比及其深层油气地质意义

摘要

利用3种有机质类型的海相烃源岩,分别在温压共控模拟和常规高压釜模拟两种温压体系下开展生烃模拟实验.在系统对比两种模拟方式产物产率、有机地球化学特征基础之上,分析了静岩压力和流体压力、水的性质与相态对烃源岩生烃过程与生烃机理的影响,探讨了实验结果在深层油气勘探中的地质意义.实验结果对比表明,高静岩压力和流体压力以及高温压缩态水的存在对有机质生烃演化具有明显控制作用,主要表现在以下几点:(1)有机质镜质组反射率受到“抑制”,成熟阶段原油生成被延迟,高过成熟阶段延缓原油向烃气转化;(2)原油和原油裂解气产率增加,干酪根裂解烃气、CO2和H2非烃气产率降低;(3)原油产物中非烃和沥青质组分含量增加,烃气产物干燥系数相对较低、碳同位素值更偏负;(4)促进了干酪根“解聚型”生成油气方式的发生,抑制了“官能团脱除型”生成油气方式的发生.实验结果为深层油气资源评价、勘探深度下限厘定、烃类相态预测提供了有价值的信息.%By using three types of marine source rocks with different kerogen type,the authors carried out two groups of hydrocarbon-generating simulation experiments in two kinds of simulation systems with different temperature-pressure conditions.Based on the comparison of hydrocarbon-generating productivities and geochemical features of hydrocarbon products obtained in two kinds of simulation experiments,the influence of lithostatic pressure,fluid pressure and water phase on the hydrocarbon-generating model and mechanism was analyzed.And the geological significance of the experimental results for deep reservoir exploration was discussed.The results of simulation experiments with high lithostatic pressure,fluid pressure and high-temperature squeezed water (HTSW) existence showed that:(1)the vitrinite reflectance (Ro％) of remnant organic matter was restrained,crude oil generation and cracking process were delayed;(2) oil and oil cracking gas yields were enhanced,but the kerogen cracking hydrocarbon gas yield,CO2 yield and H2 yield were reduced;(3) oil products had high contents of asphaltene component and non-hydrocarbon component,and the hydrocarbon gas products had relatively low dry coefficients and relatively negative carbon isotopic values;and (4) the hydrocarbons generated by the mode of kerogen molecules depolymerization were promoted,whereas those generated by the mode of defunctionalization were restrained.Comparison experiment results provide valuable information for the evaluation of deep reservoir resource potential,determination of maximum depth limit of deep reservoir exploration,and prediction of deep hydrocarbon phase state.