煤系源岩排烃门限影响因素的模拟计算

利用生烃量减去残烃量的方法研究了煤系源岩排烃门限。数值模拟计算结果表明 ,煤和煤系泥岩的排烃门限随有机质生烃潜力的增强而变早 ,随有机质丰度的升高而变浅 ,但丰度升高到一定程度之后 ,对排烃门限的影响已不明显。随地温梯度的升高 ,排烃门限深度也变浅 ,但成熟度门限升高。煤及煤系泥岩的排气门限一般早于排油门限 ,排气量大于排油量。进入生烃门限的源岩不一定进入排烃门限 ,而进入排烃门限的源岩也不一定进入传统意义上的生烃门限。因而 ,由排烃门限来评价源岩可能比由生烃门限来评价源岩更为客观

SIMULATION AND CALCULATION OF THE FACTORS INFLUENCING THE CRITICAL THRESHOLD OF HYDROCARBONS EXPELLED FROM SOURCE ROCKS IN COAL-MEASURES

Based on the relation between amount of hydrocarbons of generation and that of retention, the hydrocarbon expelled from the source rocks in coal\|measures is simulated and calculated. The results show that the critical th reshold of hydrocarbon expelled from coal and mudstones in coal\|measures gets early with raise of hydrocarbon generated potentials from organic matter and organic abundance, which does not affect the critical threshold when it increases to a certain extent. The depth of critical threshold of expelled hydrocarbon is lowered with the increase of geotemperature gradient. The critical threshold of gas expelled from coal and mudstones is generally earlier than that of oil, and the amount of expelled gas is greater than that of oil. The source rocks entering the critical threshold of hydrocarbon generation does not necessarily enter that of hydrocarbon expulsion, and those that have entered the critical threshold of hydrocarbon expulsion also does not necessarily enter the traditional threshold of hydrocarbon generation. Therefore source rocks evaluation by the threshold of hydrocarbon expulsion may be more objective than that of hydrocarbon generation.