###### Abstract
According to this theory, gravity and buoyancy forces are ignored, and the stability of the nanofluid depends only on the total interaction energy between nanoparticles. The total energy is the sum of Van der Waals attractive force and electrical double layer repulsive force. As nanoparticles approach each other, the distance between them changes, and that changes the total interaction energy. Van der Waals attractive energy increases as the nanoparticles get closer, and when it becomes stronger than the electrical double layer repulsive force, nanoparticles will form a cluster. The clusters will form sediment if they reach a large enough size [2]. Numerous factors, including nanoparticles' size and concentration, the dielectric constant of the base fluid, and zeta potential of the nanoparticles, affect the total potential energy between the nanoparticles [2; 20] and affect nanofluid stability. The pH value of the nanofluid and its zeta potential are correlated [2; 21]. When a material is submerged in an electrolyte solution, it is usually charged because of the adsorption of ions on the material's surface, or ionization of dissociable surface groups. Ions that determine the material's surface charge are called potential-determining ions or PDIs [21]. As mentioned, the zeta potential affects the total interaction energy and causes the pH control method to affect the performance of nanofluids and permeability damage. The pH condition for less retention and permeability damage should satisfy the following two conditions:  
* The pH value is far from the point of zero charge, so the corresponding zeta potentials of nanoparticles and rock surface are high. When the pH value is at or near the point of zero charge, the nanofluid loses its stability because of the weak repulsive force [8]. * The pH value is higher or lower than the point of zero charge so that the signs of zeta potentials of nanoparticles and rock surface match each other. Not satisfying these conditions eventually results in an attractive total potential energy that results in low nanofluid stability and high adsorption of nanoparticles on the rock surface. Carbon dioxide (CO\({}_{2}\)) gas on its own is used in several enhanced oil recovery methods, such as water alternating gas (WAG), huff and puff, and continuous gas injection [22]. CO\({}_{2}\) injection is a win-win strategy to improve oil production and reduce greenhouse gas emissions by sequestering CO\({}_{2}\) inside the oil reservoir formations [22; 23]. Furthermore, the ability of CO\({}_{2}\) gas to dissolve in water and produce carbonic acid (H\({}_{2}\)CO\({}_{3}\)) can be exploited for pH control [24]. A large number of research studies related to using nanoparticles in the oil and gas industry have focused on silicon dioxide (SiO\({}_{2}\)) nanoparticles [4; 5]. However, other types of commercially available nanoparticles have promising potentials. Among these types is aluminum oxide (Al\({}_{2}\)O\({}_{3}\)) nanoparticles, which have proven to be effective for enhanced oil recovery applications [5; 6; 10]. However, similar to the other types of nanoparticles, Al\({}_{2}\)O\({}_{3}\) nanoparticles tend to cause permeability damage. In the case of Al\({}_{2}\)O\({}_{3}\) nanoparticles, changing the pH of the base fluid (increasing or decreasing the concentration of H\({}^{+}\) ions) changes the surface charge and zeta potential, as displayed in Figure 1[25], which changes the stability and interaction energy between Al\({}_{2}\)O\({}_{3}\) nanoparticles and the rock surface. This study experimentally investigated the efficiency of the pH control method for reducing the permeability damage caused by the injection of Al\({}_{2}\)O\({}_{3}\) nanofluids. The study involved performing core flooding experiments at various pH conditions and comparing the permeability damage results. DLVO theory calculations, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis were performed to confirm and evaluate nanoparticle retention.