Browsing by Author "Bai, Chutian"

Now showing 1 - 4 of 4
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    Application of magnetic nanoparticles as demulsifiers for surfactant-enhanced oil recovery
    (Wiley, 2023) Zhang, Leilei; Bai, Chutian; Zhang, Zhuqing; Wang, Xinglin; Nguyen, Thao Vy; Vavra, Eric; Puerto, Maura; Hirasaki, George J.; Biswal, Sibani Lisa
    Nonionic surfactants are increasingly being applied in oil recovery processes due to their stability and low adsorption onto mineral surfaces. However, these surfactants lead to the production of emulsified oil that is extremely stable and difficult to separate by conventional methods. This research characterizes the stability of crude oil mixed with a nonionic surfactant, L24–22, in a brine solution. When subjected to gravity separation, a middle oil-rich and bottom water-rich emulsion are generated for various water–oil ratios. Thermal treatments can effectively break oil-rich emulsions, but the bottom water layer remains contaminated with micron-sized crude oil droplets. A magnetic nanoparticle treatment is shown to demulsify the crude oil emulsions, dropping the total organic carbon (TOC) in the water layer from 1470 to 30 ppm.
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    Distinguishing the Effect of Rock Wettability from Residual Oil on Foam Generation and Propagation in Porous Media
    (American Chemical Society, 2021) Amirmoshiri, Mohammadreza; Wang, Xinglin; Bai, Chutian; Tewari, Raj Deo; Xie, Sheena Xina; Bahrim, Ridhwan Zhafri Kamarul; Singer, Philip M.; Farajzadeh, Rouhi; Biswal, Sibani Lisa; Hirasaki, George. J.
    One of the common challenges of applying foam for enhanced oil recovery is the foam instability in the presence of crude oil and nonwater-wet surfaces. In this experimental study, we systematically distinguish the effect of rock surface wettability from that of crude oil saturation on foam rheology under reservoir conditions. Neutral-wet Berea and reservoir sandstone cores are prepared by aging with crude oil, followed by the wettability index measurements. Transient foam generation and steady-state foam quality scans are conducted in neutral-wet cores, with/without water-flood residual oil. Nuclear magnetic resonance imaging is also utilized to measure the remaining oil saturation at the end of the foam-flood. It is shown that strong foam can be generated in a neutral-wet core with no residual oil because of the solubilization of the adsorbed crude oil components and the wettability alteration toward more water-wet conditions. However, in a neutral-wet core containing residual oil, foam generation is initially hindered. Foam generation occurs after injecting several pore volumes of surfactant solution and increasing the superficial velocity to overcome the minimum pressure gradient required for in situ foam generation. The findings from this study suggest that surface wettability in the presence of bulk oil saturation significantly affects transient foam generation. The final steady-state foam strength becomes comparable to the water-wet and oil-free case once the residual oil saturation is adequately reduced.
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    Fundamental Insights of Foam Transport in Porous Media Applied to Enhanced Oil Recovery
    (2023-04-17) Bai, Chutian; Hirasaki, George J; Biswal, Sibani Lisa
    Foams are colloidal systems that consist of gas bubbles dispersed in a liquid. Porous media, such as rocks or soil, have complex pore structures that can trap and hold fluids, including foam. Foam can exhibit unexpected behavior while flowing through porous media, leading to ambiguous or contradictory experimental results. The transport of aqueous foam in porous media has become an increasingly popular subject of research lately. A strong motivation to comprehend the fundamental physical and chemical processes that accurately describe and predict the nature of foam flow in porous media is that there are many potential applications, such as enhanced oil recovery (EOR) and carbon dioxide storage. Determining the capillary pressure during foam flow in porous media is important because bubbles are thought to coalesce by lamella rupture as the "limiting capillary pressure" is approached. In this thesis, the roles of surfactant concentration, liquid and gas flowrate, system pressure, temperature, and gas type on capillary pressure and apparent viscosity of foam flowing through porous media are explored. Furthermore, a novel probe design for directly measuring the in-situ capillary pressure is proposed. An application of foam EOR is demonstrated in this thesis as well.
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    Measuring in-situ capillary pressure of a flowing foam system in porous media
    (Elsevier, 2022) Vavra, Eric; Puerto, Maura; Bai, Chutian; Ma, Kun; Mateen, Khalid; Biswal, Lisa; Hirasaki, George
    Hypothesis: Capillary pressure (Pc) is an intrinsic property of aqueous foams that has been demonstrated to play an important role in lamella rupture. Thus, directly measuring in-situ capillary pressure of a foam flowing through porous media has potential to greatly improve understanding of this complex process. Experiments: A capillary pressure probe was constructed and validated. Direct measurements of capillary pressure were made at ambient conditions during foam quality scan experiments in a transparent 1.41 × 10−10 m2 (143-Darcy) homogenous sand pack conducted at constant gas velocity. The foam texture was simultaneously visualized at the wall of the sand pack via microscope. Findings: In the low-quality regime, a plateauing trend in Pc was identified. In-situ microscopic visualization of the flowing foam revealed that gas bubbles were convecting with a fine discontinuous texture while Pc is at the plateau value Ppc. In the high-quality regime, the measured capillary pressures first decreased with increasing quality before increasing again at the driest qualities. These changes in Pc correlated with foam bubbles becoming coarser with increasing injected gas fractional flow before transitioning to continuous-gas flow at the slowest and driest injection conditions. These findings have been previously unreported for steady-state flow conditions and shall have significant implications for the general physical description of foam flow in porous media.