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为了解压力对有机质热演化和成烃过程的影响,利用高压生烃模拟仪,在一定半开放体系中,对采自钻孔的泥质烃源岩样品进行了恒压与增压2个系列的生烃模拟实验。恒压系列中,沥青、热解油和气态烃产率高峰分别出现在350℃、520℃和520℃,产率依次为6.17mg/g、12.07mg/g和4.14mL/g,对应镜质体反射率(R_O)分别为0.9%、3.0%和3.0%,排烃次数分别为4次、21次和21次。增压系列中,沥青、热解油和气态烃产率高峰分别出现在350℃、500℃和520℃,产率依次为12.56mg/g、24.87mg/g和2.59mL/g,对应R_O值分别为1.1%、3.1%和3.1%,对应排烃次数分别为5次、43次和44次。表明在半开放体系中,排烃次数受到温度和排烃压力阈值的共同控制,温度升高引起生烃强度增加,在同一排烃压力阈值条件下,体系内压力不断上升,达到排烃压力阈值上限,导致排烃次数增加,而排烃次数增加可能有利于液态烃的形成。流体压力的升高可能会促进沥青和热解油的形成,导致液态烃产率升高。同时,流体压力的升高也可能不利于气态烃的形成,会降低气态烃产率。流体压力对有机质R_O值的影响在不同温度阶段不尽相同,400~500℃区间R_O值随流体压力升高明显增加。
In order to understand the effect of pressure on thermal evolution and hydrocarbon generation of organic matter, two series of constant pressure and pressure increasing were carried out on the samples of muddy source rocks collected from boreholes in a certain semi-open system by using high pressure hydrocarbon generation simulator. Hydrocarbon generation simulation experiment. In the constant pressure series, the peaks of bitumen, pyrolysis oil and gaseous hydrocarbon yield appeared at 350 ℃, 520 ℃ and 520 ℃, the yields were 6.17mg / g, 12.07mg / g and 4.14mL / g in turn, the corresponding vitrinite The body reflectivity (R_O) was 0.9%, 3.0% and 3.0%, respectively, and the hydrocarbon expulsion times were 4 times, 21 times and 21 times respectively. In the supercharging series, the peaks of bitumen, pyrolysis oil and gaseous hydrocarbon yield appear at 350 ℃, 500 ℃ and 520 ℃ respectively, the yields are 12.56mg / g, 24.87mg / g and 2.59mL / g, respectively, corresponding to R_O value Respectively, 1.1%, 3.1% and 3.1%, corresponding to the number of hydrocarbon emissions were 5 times, 43 times and 44 times. It shows that in the semi-open system, the hydrocarbon expelling times are jointly controlled by the temperature and the threshold pressure of hydrocarbon expulsion, and the increase of hydrocarbon generation intensity is caused by the temperature increase. Under the same threshold pressure of hydrocarbon expulsion, the pressure in the system rises continuously and reaches the threshold Upper limit, leading to an increase in the number of hydrocarbon expelling, whereas an increase in the number of expelling hydrocarbons may be advantageous for the formation of liquid hydrocarbons. The increase of fluid pressure may promote the formation of bitumen and pyrolysis oil, resulting in the increase of liquid hydrocarbon yield. At the same time, an increase in fluid pressure may also be detrimental to the formation of gaseous hydrocarbons, reducing the yield of gaseous hydrocarbons. The influence of fluid pressure on the R_O value of organic matter is different at different temperature stages. The R_O value in the range of 400 ~ 500 ℃ increases with the increase of fluid pressure.