Wettability Alteration in Low-Permeability Sandstone Reservoirs by “SiO₂–Rhamnolipid” Nanofluid

Abstract

The wettability condition of a rock’s surface is an enormous parameter for enhanced oil recovery (EOR) in low-permeability reservoirs. It determines the spreading of injected water and the adhesion of residual oil on rock surfaces. In this study, a new nanofluid composed of silica nanoparticles and rhamnolipid in brine was utilized as an effective agent to alter the wettability of a rock’s surface. In order to obtain rock surfaces with different initial wettabilities, hexamethyldisilazane (HMDS) was used for the sample preparation. The measurement of three-phase contact angles for water/air/rock and brine/oil/rock were performed to explore the contact situation between a rock surface and movable fluids, and the spontaneous imbibition test researched the process of oil recovery with nanofluid. By evaluating the experimental measurements, nanofluid showed a significant potential in wettability alteration from oil-wet toward water-wet state, which is an important mechanism for “scraping” oil drops from a rock surface during nano-EOR process. Moreover, a total of nine coreflooding tests were performed to investigate the effects of rock wettability on waterflooding and nanofluid flooding, respectively. The results revealed that an intermediate-wet state of a rock’s surface is in favor of the oil recovery especially for waterflooding, and nanofluid, resulting in an additional 5.3–6.8% increments in oil recovery compared to conventional waterflooding. In conclusion, nanofluids show a significant potential for EOR from low-permeability cores, implying a wide application in oil fields.

Synergistic Effects of SiO2-Rhamnolipid Nanofluid on Oil-Water Distribution in Low-Permeability Reservoirs

“…Firstly, 40 ppm of rhamnolipid biosurfactant (at the CMC) was added to NaCl brine and homogenized for 10 min using a magnetic stirrer. The optimum efficiency of rhamnolipid with CMC in stabilizing nanofluid and recovering crude oil has been reported in previous studies. - Afterward, a known amount of SiO 2 nanoparticles was dispersed to the rhamnolipid solution and sonicated 30 times at 400 W for 1 min with 1 min rest to avoid aggregation and precipitation of the nanoparticles. In order to balance the oil displacement effect and system stability, the particle concentration of nanofluid has been set as 1000 ppm in this study …”

Synthesis of colloidal silica nanofluid and assessment of its impact on interfacial tension (IFT) and wettability for enhanced oil recovery (EOR)

“…Wang et al 24 studied wettability alteration of low permeability sandstone cores. In this study, they employed SiO 2 -Rhamnolipid nanofluid for enhanced recovery.…”

Novel Robust Three-Dimensional Field-Scale Reservoir Modeling Development of Nanoparticles for Improved and Enhanced Oil Recovery

“…These findings are summarized in Figure . The alteration of wettability is widely recognized as the most commonly accepted process among researchers. ,− …”