Potential Application of Silica Nanoparticles for Wettability Alteration of Oil–Wet Calcite: A Mechanistic Study

Abstract

Oil recovery from carbonate reservoirs can be enhanced by altering the wettability from oil-wet toward water-wet state. Recently, silica nanoparticle (SNP) suspensions are considered as an attractive wettability alteration agent in enhanced oil recovery applications. However, their performance along with the underlying mechanism for wettability alteration in carbonate rocks is not well discussed. In this work, the ability of SNP suspensions, in the presence/absence of salt, to alter the wettability of oil-wet calcite substrates to a water-wet condition was investigated. In the first step, to ensure that the properties of nanofluids have not been changed during the tests, stability analysis was performed. Then, low concentration nanofluids were utilized, and transient as well as equilibrium behavior of wettability alteration process were analyzed through contact angle measurement. Moreover, a mechanism for a wettability alteration process was proposed and verified with different tools. Results showed that the SNP suspensions could effectively change the wetness of strongly oil-wet calcite to water wet (e.g., from 156° to 41.7° at 2000 mg/L nanofluid). This ability was enhanced by increasing concentration, time, and salinity. Two equations were proposed to predict the equilibrium and transient contact angles with a good agreement. Analyzing the transient behavior of the wettability alteration indicated that the rate constant increased from 0.0019 to 0.0021 h–1 with the increase in nanofluid concentration from 500 to 1000 mg/L. It was further increased to 0.0026 h–1 for 1000 mg/L in 0.05 M electrolyte solution. The partial release of carboxylate groups from the oil-wet calcite surface and their replacement with SNP was suggested to be the responsible mechanism for wettability alteration. Surface equilibria and interaction studies, Fourier transform infrared spectroscopy, and scanning electron microscopy provided verification in support of the proposed mechanism. The enhanced wettability alteration in the electrolyte media was attributed to the role of Na+ ions facilitating the adsorption and release of SNP and stearates, respectively. In addition, the presence of electrolyte favorably affected the position of the system’s equilibria.

A review of nanomaterials for nanofluid enhanced oil recovery

“…2. The same wettability alterations by nanoparticles and the nanoparticle mixture were also reported by Giraldo et al, 17 Maghzi et al 18 and Dehghan Monfared et al 12 According to above literatures, wettability alteration can be affected by particle size, cosurfactants, pH value and ion strength. 10 We have also noticed that some researchers claimed SiO 2 nanoparticles can also be applied as an augmented injection agent.…”

“…Wettability alteration is a well-known practice for oil-wet and mix-wet formation enhanced oil recovery. 11,12 Formation surface contacted and reacted with underground oil reserve for millions of years before recovery processes were developed, so reservoirs normally show oil-wet or mix-wet formations. By changing formation wettability, capillary force will decrease and mobility of the oil phase will be enhanced.…”

“…Examining results obtained from laboratories, it appears that nanooodings techniques have advantages over conventional ooding techniques for oil emulsication, wettability alteration and foam stabilization, and they possess unique mechanisms for oil displacement. 6,12,17,27 Before practical application, however, nanomaterials must be assessed to determine if they satisfy a criterion to carry out an enhanced oil recovery operation successfully without causing damage to the reservoir. Following are several factors that can affect nanoooding quality: Nanomaterial structure A major concern of applying nanoparticles in EOR is material swelling causing formation jamming and formation damage 71 especially for unmodied clay nanomaterials with layered structures which can be intercalated with formation water.…”

The effect of nanoparticles on reservoir wettability alteration: a critical review

“…3). In this regard, many researchers have pointed out that nanofluid can modify the wettability of rock surface (Dehghan Monfared et al 2016). Nanoparticles are adsorbed on the rock surface and form nanotextured surfaces, which changes the rock morphology and makes it semi-homogeneous (Al-Anssari et al 2017).…”

Effect of Silica Nanoparticles on Fluid/Rock Interactions during Low Salinity Water Flooding of Chalk Reservoirs

“…Nanofluid are prepared in brines and some studies have investigated the combined role of salinity and NPs on the wettability change process [51] and NP adsorption on mineral surfaces [52]. Hendraningrat and Torsaeter [51] stated that nanofluid flooding is sensitive to water salinity especially in the presence of divalent ion (Ca 2+ and Mg 2+ ).…”