(28b) Use of Nanoparticles to Control Formation Damage Due to Fines Migration in the Production - State of the ART

The migration of fine particles occurs when the existing balance in the interaction between the rock and the reservoir fluid is altered due to the viscous and interfacial forces that promote the movement of particles weakly adhered to the pores. This can occur during the reservoir's different phases of crude oil recovery, such as drilling, production, hydraulic fracturing, and workover operations^[1]. It usually occurs during the production stage, when the fluid within the reservoir moves towards the wellbore and the fluid velocity increases. As the fluid reaches the critical flow rate, the fine particles (density <1400 kg/m³, diameter <37 microns)^[2], present in the formation, break off and are absorbed by the fluid. However, minerals in the porous medium (clays, amorphous silica, quartz, etc.), can also cause damage due to acceptable migration.

Fine particles deposited along flow channels can promote or obstruct fluid flow within the reservoir. These particles are not always small enough to pass through the pore throat, becoming trapped and accumulating in smaller pore spaces or thinner pore throats (Figure 1a). This causes clogging of the pores and decreased permeability, thus reducing the production rate. This event is one of the main reasons for the decrease in the productivity of oil and gas wells, affecting the profitability of the projects. This article is aimed at a bibliographic review of the use of nanoparticles, in those cases associated with formation damage resulting from the migration of fines, developed by various researchers in the production stage. The forms and techniques applied for its control are considered to group the existing scientific evidence on the topic and consider the research recommendations.

The migration of fines involves three main steps: the presence of fine particles in the rock or weakly cemented to the porous matrix that can be released and mobilized^[3]; the breakdown mechanism leading to the destruction of fines; and trapping of fines at specific locations due to wettability, ion attraction, or bridging^[4]. The study of the movement of particles in a porous medium is complex due to the nature and complexity of the forces that control the movement of particles within it. A porous medium consists of a solid part with many microscopic pores inside, plus the throats or gaps between them. This network of narrow conduits is the path through which the fluid can cross the medium^[5]. Oil fields are initially produced by a natural impulse, which decreases with increasing production and finally reduces at the end of primary production. In other words, the extraction of oil fluids and connate formation water leads to an increase in the local formation pressure or effective stress, which acts on the reservoir rock, causing a decrease in the local pore pressure to counteract these forces. According to the fines migration theory ^[6], each (refined) particle traveling along the pore channel is considered with four forces acting on the pore wall (Figure 1b and Figure 1c). Other forces responsible for separating the fines are the Van der Waals attractive forces, the Born repulsive forces, the double layer phenomenon, and the hydrodynamic forces that overcome the detachment of fine particles in the porous medium. That is, when the total interaction energy between the particle and the porous surface becomes positive, then the repulsive forces are more significant than the attractive forces, which occurs at the moment when the fines are released^[7].

Various mechanisms occur during production, among which the adsorption of particles on the exterior of the rock or its surface stands out, a product of Brownian movement and electrostatic interaction between the migrating particles and the exterior or solid surface of the pores^[8]. Various researchers have studied the effect of different factors on producing fines, such as salinity, flow rate, pH, residual oil saturation, temperature, wettability, crude oil polarity, and flow fractional water and crude oil^[9].

Different methods have been reported in the literature to solve the problems of formation damage resulting from the migration of fines. These methods have been applied; however, some have failed, others have been ineffective, and others include nanoparticles (NPs). The latest have reported good results as inhibitors and stabilizers of fines migration, due to its unique characteristics, such as its high surface/volume ratio, which gives it the particularity of having a large contact area and, consequently, an increase in the surface energy of the particle^[10].

In addition, nanoparticles have a high resistance to degradation in media with high salinities and temperatures^[11]. This suggests that the nanoparticles can be adapted to the reservoir conditions, allowing an adequate flow of them through the pores of the reservoirs, also facilitating the treatment within the porous medium to control damage to the formation by migration of particles ^[12]. Table 1 summarizes some research on nanoparticles that inhibit and stabilize formation damage due to fines migration. According to the laboratory investigations and field applications shown in Table 1, no evidence that using NPs causes a deterioration in permeability. NPs represents an advantage compared to other chemicals and techniques used to control the migration of fines in formations.

Conclusions

The fine particles present in the porous medium tend to migrate. These particles can be retained or deposited within the pore matrix; therefore, they can reduce the porosity and permeability of the porous medium and cause damage to the formation. As the pressure in the reservoir spaces is depleted at the pore level, the effective stress increases. This increased stress compresses the reservoir pore configurations, inducing greater particle detachment. The literature review suggests that applying NPs could become an integral part of the oil extraction processes that, in the cases evaluated, potentially improve the oil production stage, providing an effective solution to control the migration of fines. It is essential to note that the effectiveness of this method may depend on several factors, including the specific wellbore and formation conditions, as well as the implementation strategy.