Frontier Enhanced Oil Recovery (EOR) Research on the Application of Imbibition Techniques in High-Pressure Forced Soaking of Hydraulically Fractured Shale Oil Reservoirs

Shale reservoirs are characterized by low porosity and low permeability, and volume fracturing of horizontal wells is a key technology for the benefits development of shale oil resources. The results from laboratory and field tests show that the backflow rate of fracturing fluid is less than 50%, and the storage amount of fracturing fluid after large-scale hydraulic fracturing is positively correlated with the output of single well. The recovery of crude oil is greatly improved by means of shut-in and imbibition, therefore attracting increasing attention from researchers. In this review, we summarize the recent advances in the migration mechanisms and stimulation mechanisms of horizontal well high pressure forced soaking technology in the reservoirs. However, due to the diversity of shale mineral composition and the complexity of crude oil composition, the stimulation mechanism and effect of this technology are not clear in shale reservoir. Therefore, the mechanism of enhanced oil recovery by imbibition and the movable lower limit of imbibition cannot be characterized quantitatively. It is necessary to solve fragmentation research in the full-period fluid transport mechanisms in the follow-up research.

Automated summary

Shale reservoirs with low porosity and permeability benefit from volume fracturing of horizontal wells for the development of shale oil resources. Recent advances in high pressure forced soaking technology in horizontal wells have shown improved recovery rates through shut-in and imbibition methods, attracting increased attention from researchers. However, the stimulation mechanism and effects of this technology in shale reservoirs remain unclear due to the complexity of shale mineral composition and crude oil composition. Further research is needed to quantitatively characterize the enhanced oil recovery mechanism and the movable lower limit of imbibition in fragmented fluid transport mechanisms.