Contribution of different shale storage spaces to recovery rate and mechanism of oil mobilization during imbibition

The influence of different reservoir spaces in shale reservoirs on imbibition recovery is a hot spot for improving shale oil recovery. However, the research on the influence of different chemical reagents on the recovery factor of different scale pores is limited, and the influence mechanism of shale imbibition recovery factor under the action of different media has not been systematically studied. Therefore, this study takes the Gulong shale oil reservoir as the research object, carries out imbibition experiments combined with nuclear magnetic resonance testing under different injection fluid conditions, quantifies the contribution of shale pores of different scales to imbibition recovery under different injection media conditions, and analyzes the influence of injection media types on imbibition recovery. The results show that the average contribution rate of different types of pores was in the order of interlayer clay (47.6%) > mesoscale pores (32.7%) > small pores (17.3%) > large pores (2.6%). The total imbibition recovery of shale with millimeter-scale sandy laminae was ranked as alkali solution (61.50%) > acid solution (60.92%) >GJ surfactant (39.79%)> distilled water (32.92%)>guanidine gum (30.38%) , and the total imbibition recovery of laminated shale was ranked as GJ surfactant (39.1%) > slick water (38.0%) > guanidine gum (34.7%) > distilled water (29.2%). Document Type: Original article Cited as: Wei, J., Wang, A., Wang, R., Yang, Y., Zhao, X., Zhou, X. Contribution of different shale storage spaces to recovery rate and mechanism of oil mobilization during imbibition. Capillarity, 2025, 15(1): 12-24. https://doi.org/10.46690/capi.2025.04.03