The shale oil of Lucaogou Formation in Jimsar Sag has the characteristics of extremely low original permeability and high viscosity of crude oil,making it uneconomical to produce under natural conditions.Field practices have demonstrated that dense drilling combined with high-intensity volume fracturing is one of the most effective means to achieve large-scale development of shale oil.However,how to slow down the decline rate of oil wells and improve the recovery rate per well remains a pressing issue to be addressed.From 2019 to 2022,the researches and field tests of CO2 pre-fracturing assisted production technology were carried out in Jimsar shale oil block.The application effect of CO2 pre-storage fracturing and CO2 huff and puff in Jimsar shale oil block was systematically studied and analyzed.The results indicate that supercritical CO2 has the effects of miscible energy increase,dissolution to improve reservoir conditions,improve imbibition replacement efficiency,and increase the complexity of fracture network.The optimal injection volume,injection speed,and injection methods were determined,and a preliminary technological system for CO2 pre-fracturing in shale oil reservoirs was established.According to the prediction of production data,the CO2 pre-fracturing process can increase the final recovery rate by about 20％,which provides a reference for realizing the benefit development of shale oil and improving the development effect of other types of shale reservoirs.
关键词
CO2前置/储层改造/裂缝扩展规律/参数优化/吉木萨尔页岩油
Key words
CO2 pre-energizing fracturing/reservoir modification/crack propagation law/parameter optimization/Jimsar shale oil
万方数据