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为探究半开放体系中流体压力对烃源岩热演化和成烃过程的影响,利用高温高压(HTHP)模拟仪,在一定半开放体系中,对采自钻孔的泥岩样品进行恒压和增压2个系列的生烃模拟实验。恒压实验中沥青、热解油和气态烃产率高峰分别出现在350℃、450℃和520℃,产率依次为1.82mg/g、4.86mg/g和2.67mL/g,对应镜质体反射率(R_O)分别为0.68%、1.72%和3.0%。增压实验中,沥青、热解油和气态烃产率高峰也分别出现在350℃、450℃和520℃,产率依次为0.56mg/g、5.41mg/g和2.61mL/g,对应R_O值分别为0.56%、2.42%和2.74%。表明在半开放体系中,流体压力的升高虽不利于沥青形成,但可能会通过促进热解油的形成,从而使总液态烃产率升高。同时,流体压力的升高可能不利于气态烃的形成,会降低气态烃产率。指示在不同的热演化阶段,流体压力对有机质热演化和成烃过程有不同的影响。此外,增压实验中所得残渣总有机碳(TOC)含量均低于恒压实验,表征生烃潜力的相关指标S_2、I_H、H/C也均低于恒压实验,表明高流体压力虽可提高有机质成烃效率,但在促进有机质成油的同时也降低了残渣的生烃潜力。不同热演化阶段流体压力对有机质成熟度的相关指标T_(max)值和R_O值也有不同影响,热解油大量生成阶段T_(max)值、R_O值随流体压力升高明显增加。
In order to explore the effect of fluid pressure on the thermal evolution and hydrocarbon generation process of hydrocarbon source rock in the semi-open system, using the HTHP simulator, the mudstone samples from the borehole were subjected to constant pressure and increase in a certain semi-open system Pressure 2 series of hydrocarbon generation simulation experiment. In the constant pressure experiment, the peak of the yield of pitch, pyrolysis oil and gaseous hydrocarbon appeared at 350 ℃, 450 ℃ and 520 ℃, the yields were 1.82mg / g, 4.86mg / g and 2.67mL / g respectively, Reflectance (R_O) were 0.68%, 1.72% and 3.0% respectively. During the pressurization experiments, the peaks of bitumen, pyrolysis oil and gaseous hydrocarbon yield also appeared at 350 ℃, 450 ℃ and 520 ℃ respectively, and the yields were 0.56mg / g, 5.41mg / g and 2.61mL / g, respectively, corresponding to R_O The values were 0.56%, 2.42% and 2.74% respectively. It shows that in the semi-open system, the increase of fluid pressure is not conducive to asphalt formation, but may increase the total liquid hydrocarbon yield by promoting the formation of pyrolysis oil. At the same time, an increase in fluid pressure may be detrimental to the formation of gaseous hydrocarbons, reducing the yield of gaseous hydrocarbons. It indicates that fluid pressure has different effects on the thermal evolution and hydrocarbon generation of organic matter during different stages of thermal evolution. In addition, the total organic carbon (TOC) content of the residue obtained in the pressurization experiment was lower than that of the constant pressure experiment, and the relative indexes S 2, I_H and H / C that characterize the hydrocarbon generation potential were also lower than the constant pressure experiments, indicating that the high fluid pressure Improve the efficiency of organic matter hydrocarbon generation, but to promote the organic matter into the oil while also reducing the hydrocarbon potential of the residue. In different stages of thermal evolution, the fluid pressure has a different effect on T_ (max) and R_O of organic matter maturity, and the value of T_ (max) in the mass production phase of pyrolysis oil increases with the rise of fluid pressure.