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 CO

2

pre-fracturing assiste

d production technology were carried out in Jimsar shale oil block. The application effect of CO

2

pre-storage fracturing and CO

2

huff and puff in Jimsar shale oil block was systematically studied and analyzed. The results indicate that supercritical CO

2

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 CO

2

pre-fracturing in shale oil reservoirs was established. According to the prediction of production data

the CO

2

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.