Precise Wettability Characterization of Carbonate Rocks To Evaluate Oil Recovery Using Surfactant-Based Nanofluids

Abstract

Free energy of nanoparticles can increase the surface activity at the solid/oil/liquid contact line and remove oil through the disjoining pressure gradient mechanism. Surfactants can also remove oil mainly by reducing interfacial tension, although raising economic concerns as a result of their adsorption on the rock surface. Introduction of nanoparticles to surfactant solutions seemed to be more prominent in improving the wettability than reducing the interfacial tension, which could offer an opportunity to develop cost-effective chemical flooding agents to enhance oil recovery in carbonate reservoirs. However, characterization of wettability alteration using contact angles typically fails in providing consistent results. In this study, the dual-drop–dual-crystal technique was employed to measure precise and reproducible dynamic contact angles and was supported by relative permeability curves generated by coreflood experiments to evaluate the wettability alteration performance of silica nanoparticles combined with both effective and ineffective anionic surfactants at both ambient and high-pressure, high-temperature conditions. Adding nanoparticles to surfactants was seen to change the wettability of the carbonate rocks from strongly oil-wet to weakly oil-wet and intermediate-wet conditions (e.g., change in the advancing contact angle from 167° to 98°), which improved the oil recovery (up to 93% of the original oil in place) and reduced the residual oil saturation, without having to significantly reduce the interfacial tension (only 1 or 2 orders of magnitude). Reduction of the surfactant concentration in the combination did not significantly hinder the wettability alteration performance, showing the ability of nanoparticles to compensate for surfactants. Therefore, the combination of nanoparticles and low-cost dilute surfactants can be tuned to provide economically appealing chemical flooding agents to enhance oil recovery.

A Review on Wettability Alteration in Carbonate Rocks: Wettability Modifiers

“…136,140,142 For example, an increased concentration of silica nanoparticles (from 0 to 0.8 wt %) improved the wettability modification effect. 148 However, Al-Anssari et al found that after concentration reached a threshold value, this positive influence became insignificant. They suggested controlling the nanofluid concentration at the corresponding threshold value from an economic perspective.…”

“…Increased nanoparticle concentration has a positive influence on wettability alteration toward water-wet conditions. ,, For example, an increased concentration of silica nanoparticles (from 0 to 0.8 wt %) improved the wettability modification effect . However, Al-Anssari et al found that after concentration reached a threshold value, this positive influence became insignificant.…”

Insights into Nanoscale Wettability Effects of Low Salinity and Nanofluid Enhanced Oil Recovery Techniques

“…Through multiple mechanisms such as ion exchange and double layer expansion (a mechanism which arises when charged solids are immersed in similarly charged fluids, creating a double layer and leading to electrostatic repulsion), low salinity brine promotes the growth of thin water wetting films, reducing the work of adhesion needed to disrupt oil/rock interfaces [52]. Likewise, injecting dispersions of silicon dioxide nanoparticles into the reservoir can penetrate oil/rock interfaces by forming a wedge film [9,29,56]. By doing so, fluids containing nanoparticles will advance over the area previously occupied by the oil phase, reducing the work of adhesion to gradually change the system to a less oil-wet state.…”

“…Of these techniques, contact angle measurement is the most common because such measurements can easily be done under reservoir thermodynamic and fluid conditions; it is less time-consuming; and it can be used to probe specific mineralogical effects on wettability. Contact angles were measured using the sessile drop technique and the modified sessile drop technique until the dual-drop-dual-crystal (DDDC) technique [9] was developed. The DDDC approach helped overcome the deficiencies in the earlier methods in terms of honoring three-phase boundary, obtaining reproducible results, and requiring less aging time.…”

Synergistic Efficiency of Zinc Oxide/Montmorillonite Nanocomposites and a New Derived Saponin in Liquid/Liquid/Solid Interface-Included Systems: Application in Nanotechnology-Assisted Enhanced Oil Recovery

“…Xu et al, Cheraghian et al, Haeri et al, Songolzadeh and Moghadasi, Zhao et al, and Zhong et al. have shown that the combinations of silica nanoparticles with different surfactants have a good potential to alter wettability from oil-wet to water-wet. − Suleimanov et al showed that nonferrous metal NPs can reduce IFT/surface tension . Mohajeri et al, by combining ZrO 2 NPs with sodium dodecyl sulfate and CTAB, showed that the nanofluids optimize IFT/surface tension and alter wettability …”