Wettability Alteration of Organic-Rich Siliceous Shale by Aqueous Ketone Solution

Wettability is a crucial factor in oil production, as it influences the distribution of fluids and the transport of various components within complex and tight pore networks. Shale oil reservoirs typically exhibit mixed-wet to oil-wet characteristics, which can restrict water imbibition and impede oil flow from the rock matrix to hydraulic and natural fractures. One effective method for enhancing oil production involves injecting aqueous chemical solutions that can alter the rock’s wettability and improve flow characteristics in tight pores. For the first time, this research examined an aqueous ketone solution for modifying the wettability in organic-rich siliceous shale cores. It also included a mechanistic simulation of wettability alteration using 3-pentanone with a K-value-based compositional flow simulator. Results demonstrated enhanced oil recovery by injecting an aqueous 3-pentanone solution into a fractured shale matrix via spontaneous imbibition. Additionally, a novel experimental program was developed to measure the solubility of 3-pentanone in brines as well as the 3-pentanone K-value in mixtures of brine, oil, and 3-pentanone under liquid–liquid equilibria (LLE) at high-pressure and high-temperature (HPHT) conditions. The chemical and physical properties of 3-pentanone identified in this research provide critical data about its transport mechanisms in shale oil reservoirs. The numerical flow simulation model, calibrated with experimental data, indicated that 3-pentanone can mobilize trapped oil and enhance water imbibition by modifying the relative permeability and capillary pressure. Both experimental and simulation results demonstrated that 3-pentanone effectively alters the wettability in shale, leading to enhanced oil recovery.