川东北地区飞仙关组古油藏原油裂解型天然气的生成动力学地质模型

天然气组分、碳同位素组成以及气藏储层固体沥青的热变质成因，都说明飞仙关组古油藏确曾存在并发生了裂解，天然气主要为原油裂解气。通过高压封闭体系下的原油热裂解模拟实验，从气态烃组分及产率变化、焦沥青的生成等方面探讨了原油裂解生气特征。结合川东北地区飞仙关组的埋藏史、古地温史、构造演化等地质因素，将实验结果外推至地质条件下，建立了古油藏原油裂解生气的动力学地质模型，指出鲕滩天然气藏的形成经历了古油藏、古气藏和气藏调整定型3个演化阶段。通过动力学计算定量恢复了古油藏裂解生气的成藏过程，揭示出在不同地质年代和地质温度下甲烷（C₁）、总烃类气体（C_1-5）和焦沥青等原油裂解产物的转化率的变化。取得的动力学地质模型对古油藏原油裂解型天然气的成藏研究具有重要的实用价值。

A kinetic Geological Model of Oil Cracking Gas Formation in Feixianguan Oolitic Oil Reservoir in NE Sichuan Basin

It has been proved that the natural gas in Feixianguan reservoir in NE Sichuan basin would be generated from oil cracking in past oil pools,by means of gas geochemistry and organic petrology of solid bitumen in reservoir.Pyrolysis in anhydrous closed system (gold tubes) was subjected to discuss gas generation from oil cracking,including yields of gaseous hydrocarbons and pyrobitumen.In combination with subsidence history,paleotemperature and Feixianguan tectonics,we extrapolated experimental kinetics parameter to geological conditions and established a kinetic geological model of gas generation of oil cracking in oil reservoir,and then the history of generation,migration and accumulation of oil cracking gas in oolitic reservoir was recurred.The kinetic geological model established in this paper can give an approach to understand the accumulation of oil cracking gas in past oil pools.