川中大安寨段页岩排烃效率及其勘探启示

Hydrocarbon Expulsion Efficiency of Shale in the Da$'$anzhai Member of Central Sichuan Basin and Its Exploration Enlightenment

张本健 路俊刚 张芮 蒋奇君 肖正录

ZHANGBenjian LUJungang ZHANGRui JIANGQijun XIAOZhenglu

中国石油西南油气田公司勘探开发研究院, 四川 成都 610051 西南石油大学地球科学与技术学院, 四川 成都 610500 天然气地质四川省重点实验室, 四川 成都 610500

Research Institute of Exploration and Development, Southwest Oil and Gas Field Company, PetroChina, Chengdu, Sichuan 610051, China School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China Natural Gas Geology Key Laboratory of Sichuan Province, Chengdu, Sichuan 610500, China

烃源岩的排烃效率是油气资源评价中的重要参数，排烃效率的研究既可以指导资源评价，又可以作为验证资源评价结果可靠性的重要科学手段。基于目前生烃潜力法的缺陷，提出了改进的生烃潜力法，并利用此方法求取了四川盆地中部侏罗系大安寨段页岩的排烃效率。研究结果表明，当前地质条件下，大安寨段页岩的排烃效率分布于 0～62.6%。随着有机质成熟度（）的增加，排烃效率逐渐上升，含油饱和度指数先增加后降低。 处于0.95%～1.72%，含油饱和度指数大于 100 mg/g，页岩层系的可动烃含量较高。岩相组合对排烃效率具有明显的影响，在纵向上有页岩向介壳灰岩排烃的趋势，相较于纯页岩储层而言，互层型组合层间缝发育，有利于页岩油流动和产出。综合认为， ＞1.25% 的大一亚段下部互层型组合是大安寨段页岩油的重点勘探目标。该成果可为川中侏罗系大安寨段页岩油的勘探开发提供理论指导。

The hydrocarbon expulsion efficiency of source rock is an important parameter in petroleum resources assessment. The study of hydrocarbon expulsion efficiency can not only guide the resource evaluation, but also be an important scientific means to verify the reliability of the resource evaluation results. To remedy the defects of current hydrocarbon generation potential method, an improved hydrocarbon generation potential method is proposed, and the hydrocarbon expulsion efficiency of shale in the Jurassic Da$'$anzhai Member of central Sichuan Basin was obtained by using this method. The results show that under the current geological conditions, the hydrocarbon expulsion efficiency of the shale in the Da$'$anzhai Member is distributed between 0${\sim}$62.6{\percent}. With the increase of organic matter maturity, the hydrocarbon expulsion efficiency gradually increases, and the oil saturation index increases first and then decreases. When $R_{\rm o}$ is in the range of 0.95%${\sim}$1.72%, oil saturation index is greater than 100 mg/g, and the movable hydrocarbon content of shale strata is higher. The lithofacies combination has a significant effect on the hydrocarbon expulsion efficiency. In the longitudinal direction, there is a tendency for shale to expel hydrocarbon from shell limestone, the development of interlayer fractures in interbedded combinations is conducive to shale oil flow and production. It is concluded that the interbedded assemblage in the lower part of the first submember in the area with $R_{\rm o}$>1.25% is the key exploration target for shale oil in the Da$'$anzhai Member. The results can provide theoretical guidance for the exploration and development of shale oil in the Jurassic Da$'$anzhai Member of central Sichuan Basin.