基于数字岩心技术的致密油储层压裂液返排模拟研究

Simulation research on fracturing fluid flowback in tight oil reservoir based on digital core technology

针对致密油储层难以获得压裂液返排过程及油的赋存类型的问题,利用数字岩心技术建立了致密油储层压裂液返排模拟方法。通过探索致密油储层压裂液返排规律,确定了致密油储层中油的赋存类型,并分析了焖井时间对压裂效果的影响。结果表明:随浸泡时间变化,压裂液返排后的含油饱和度变化明显,浸泡24h后,含油饱和度降为最低值,综合考虑渗吸洗油效率,确定焖井时间;致密油储层中油的赋存类型主要以多孔状为主;焖井对储层会造成一定伤害,对油的赋存类型影响较小。该研究结果可为其他区块开展压裂后焖井研究提供技术借鉴。

In order to solve the difficulties of both obtaining the fracturing fluid flowback process and identifying the oil occurrence type in tight oil reservoir,the simulation method to the fracturing fluid flowback in tight oil reservoir was established by using digital core technology.Through exploring the flowback law of fracturing fluids in tight oil reservoir,the oil occurrence type in tight oil reservoir was determined,and the influence of well shut-in or soaking time on fracturing effect was analyzed.The results showed that the oil saturation after fracturing fluid flowback changes obviously with the time of soaking,and the oil saturation decreases to the lowest value after soaking for 24 hrs.The soaking time was determined after considering the imbibition oil sweeping efficiency.The oil occurrence type in tight oil reservoirs is mainly porous,so soaking well will cause some damage to the reservoir,but it has little influence on the oil occurrence type.The research results can provide technical reference for studying the well soaking after fracturing in other blocks.