Formation Damage Induced by Water-Based Alumina Nanofluids during Enhanced Oil Recovery: Influence of Postflush Salinity

Abstract

Injecting nanofluids (NFs) has been proven to be a potential method to enhance oil recovery. Stranded oil is produced by wettability alteration where nanoparticles form a wedge film on pore wall surfaces, which is thought to shrink the pore space of the reservoir. Furthermore, ensuring the stability of the injected NF during the application is a major challenge. A low permeability reservoir and salinity of water make the response of NF injection to the formation damage more difficult. This article, therefore, studied the formation damage induced by the injection of alumina nanofluids (Al-NFs) in a relatively low permeability (7.1 mD) sandstone core. The salinity of the postflush water was also considered to mitigate the destructive impact. Al-NF was formulated by dispersing alumina nanoparticles (Al-NPs) in an aqueous solution of sodium dodecylbenzene sulfonate (SDBS) at its critical micelle concentration (CMC, 0.1 wt %). The formation damage, inherent to Al-NF injection, was evaluated by core-flooding tests. The assays consisted of the injection of 1 PV Al-NF (0.05 wt %) at the trail of which postflush at different salinities was flooded. The study found that the salinity of the postflush has an effect on the formation damage and oil recovery factor (RF). A chase water with a salinity concentration of 3 wt % sodium chloride (NaCl) produced an RF of 8.7% compared to a base case of water-flooding with a pressure drop of up to 13 MPa across the core (70 mm in length). These results pertained to the deposition of Al-NPs at the injection end. However, lowering the postflush salinity to 1 wt % NaCl mitigated the formation damage as evidenced by the decrease in pressure (35%) and an increase in RF to 17.2%.

Nanocomposite and Nanofluids: Towards a Sustainable Carbon Capture, Utilization, and Storage

“…However, combing both the sonication and the magnetic stirring could prolong the stability of the nanofluid. Furthermore, Nguele et al [43] and later Ngo et al [47] reported that bubbling gas during the preparation could further enhance the stability regardless the type of base fluid (Figure 5).…”

“…With the presence of salt at the interface, the excess surface concentration turns positive from which results a low contact angle (Figure 7a) and higher IFT (Figure 7b). An oil production scenario in which the salt concentration is large, the salting-out effect seems to prevail [47].…”

“…Ngo et al monitored the stability of aluminabased nanofluid by combining colorimetry and spectrophotometry[47].…”

“…Figure 3.Monitoring alumina-based NFs stability using UV-Vis spectroscopy and 1-(-2pyridylazo)-2-naphthol, PAN.Adapted with permission from[47]. Copyright (2020) American Chemical Society.…”

“…Figure 7.Influence formation salinity on wettability and IFT alteration. (a) Wettability alteration modified from adapted with permission from[47]. Copyright (2020) American Chemical Society.…”