Numerical Modeling of Nanotechnology-Boosted Chemical Enhanced Oil Recovery Methods

Since it was theorized more than 50 years ago, nanotechnology has become the perfect boost for existing old technologies. The unique properties exhibited by materials at these scales have a potential to improve the performance of mature oil fields along with enhanced oil recovery (EOR) processes. Regarding polymer flooding, the influence of the (macro) molecules’ architecture on the fluid properties has been lately stressed. This chapter presents the numerical simulation of the combination of both agents in a single, combined recovery process. The presence of the nanoparticles affects the rheological behavior and the rock’s wettability, increasing the organic phase mobility. Undesirable effects such as (nano) particle aggregation and sedimentation are also considered. The polymer’s architecture has a major influence on the recovery process, improving the rheological and viscoelastic properties. On the other hand, although nanoparticles improve the viscosity as well, its main mechanism is their adsorption onto the rock and wettability modification. This chapter shows the importance of a good polymer characterization for EOR, the potential of nanoparticles acting as a boost of traditional EOR processes, and the vital role CFD techniques play to assess the potential of these agents and the optimization of the recovery strategies

Influence of physical and rheological properties of sweeping fluids on the residual oil saturation at the micro- and macroscale

Oil recovery processes depend on many factors that can be altered in order to maximize the sweeping efficiency in porous media, and one of these is the rheology behavior of the displacing agent. Furthermore, scales in the recovery process should also be considered: from the macro- to microscale systems, in which capillary forces become predominant. It is also well-known the non-Newtonian behavior of polymer solutions used in Enhanced Oil Recovery (EOR) processes. This has been considered before, explaining how the polymer’s viscosifying properties enhance the displacing process. Recently, another property exhibit by polymer solutions started being considered: the viscoelasticity. The interaction between the (macro)molecules in the displacing phase generates a complex stress field which cannot be simply addressed by an increment in the shear viscosity. We present a 2D, multiphase simulation at macro- and microscale of a recovery process with different fluid models, showing that viscoelastic fluids increase the recovery performance due to the extra stresses generated by the polymer molecules, up to a 15.4% when compared to traditional waterflooding techniques. The viscosity of the displacing phase affects indeed the recovery efficiency, and moreover, the results also evidenced that not only the bulk viscoelasticity, but also the interfacial forces play a vital role in the microscopic sweeping efficiency in polymer EOR flooding processes. This can be used when determining the properties of future EOR agents to be synthesized

Numerical Study of Turbulent Flows over a NACA 0012 Airfoil: Insights into Its Performance and the Addition of a Slotted Flap

This work provides a comprehensive overview of various aspects of airfoil CFD simulations. The airflow around a 2D NACA 0012 airfoil at various angles of attack is simulated using the RANS SST turbulent flow model and compared to experimental data. The airfoil is then modified with a slotted flap and additionally the angle of the flap is altered. The flow model is subsequently coupled to a heat transfer model to compare the isothermal versus non-isothermal performance. The airfoil with the slotted flap shows increased Cl and and Cd values compared to the standard NACA 0012. Larger flap angles further increase the Cl and Cd. The lift and drag coefficients show no difference in the non-isothermal model compared to the isothermal model, indicating the isothermal model is sufficient for this system. The 3D model without wingtips shows a similar Cl to the 2D model as it effectively has an infinite span. Adding a wingtip reduces the lift coefficient, as the air can flow around the wingtip, increasing the pressure on top of the wing. Overall, these results match the behavior expected from wing theory well, showing how CFD can be effectively applied in the development and optimization of wings, flaps, and wingtips

Surfactant–Polymer Flooding: Influence of the Injection Scheme

The use of standard enhanced oil recovery (EOR) techniques allows for the improvement of oilfield performance after waterflooding processes. Chemical EOR methods modify different properties of fluids and/or rock to mobilize the remaining oil. Moreover, combined techniques have been developed to maximize the performance by using the joint properties of the chemical slugs. A new simulator is presented to study a surfactant–polymer flooding, based on a two-phase, five-component system (aqueous and oleous phases with water, petroleum, polymer, surfactant, and salt) for a 2D reservoir model. The physical properties modified by these chemicals are considered as well as the synergy between them. The analysis of the chemical injection strategy is deemed vital for the success of the operations. This plays a major role in the efficiency of the recovery process, including the order and the time gap between each chemical slug injection. As the latter is increased, the flooding tends to behave as two separate processes. Best results are found when both slugs are injected overlapped, with the polymer in first place which improves the sweeping efficiency of the viscous oil. This simulator can be used to study different chemical combinations and their injection procedure to optimize the EOR process

Surfactant-Polymer Interactions in a Combined Enhanced Oil Recovery Flooding

The traditional Enhanced Oil Recovery (EOR) processes allow improving the performance of mature oilfields after waterflooding projects. Chemical EOR processes modify different physical properties of the fluids and/or the rock in order to mobilize the oil that remains trapped. Furthermore, combined processes have been proposed to improve the performance, using the properties and synergy of the chemical agents. This paper presents a novel simulator developed for a combined surfactant/polymer flooding in EOR processes. It studies the flow of a two-phase, five-component system (aqueous and organic phases with water, petroleum, surfactant, polymer and salt) in porous media. Polymer and surfactant together affect each other’s interfacial and rheological properties as well as the adsorption rates. This is known in the industry as Surfactant-Polymer Interaction (SPI). The simulations showed that optimum results occur when both chemical agents are injected overlapped, with the polymer in the first place. This procedure decreases the surfactant’s adsorption rates, rendering higher recovery factors. The presence of the salt as fifth component slightly modifies the adsorption rates of both polymer and surfactant, but its influence on the phase behavior allows increasing the surfactant’s sweep efficiency

Surfactant flooding: The influence of the physical properties on the recovery efficiency

Enhanced Oil Recovery (EOR) processes aim at increasing the performance and operative life of oilfields while newer, greener and more efficient energy sources are developed. Among the chemical EOR techniques, surfactant flooding is one of the most well-known methods, applied mainly in low- and medium-viscosity oilfields. Surfactants diminish the interfacial energy between the oleous and aqueous phases, reducing the forces responsible of the capillary trapping phenomenon and mobilizing the remaining oil. This paper presents the study of a novel two-dimensional surfactant flooding simulator for a four-component (water, petroleum, chemical, salt), two-phase (aqueous, oleous) system in porous media. It is aimed mainly at discussing the influence of the physical phenomena present in the reservoir during the recovery, namely: rock compressibility, diffusion, capillary pressure and adsorption. The system is numerically solved using a second-order finite difference method using the IMPEC (IMplicit Pressure and Explicit Concentration) scheme. The oil recovery factor was negatively affected when these phenomena were considered, being strongly sensitive to the adsorption. The other phenomena decreased the efficiency of the process to a lesser extent, whilst the capillary pressure did not affect significantly the flooding performance. The presence of salt in the reservoir rendered the adsorption process more relevant, with water-in-oil emulsions being more sensitive to the presence of this fourth component. This paper shows the importance of the design and optimization of chemical agents to be used in EOR before its field application

Simulation of Polymer Chemical Enhanced Oil Recovery in Ghawar Field

This paper presents a 2D model of the Ghawar field and investigates the flow behavior in the field during secondary and tertiary recoveries using a simplified well scheme. For the latter, the focus is on chemical Enhanced Oil Recovery (EOR), using polymer solutions. The difference in efficiency between secondary and tertiary recovery and the influence of factors such as degradation are analyzed and presented. Furthermore, the influence of oil viscosity on the recovery factor is investigated as well as the efficiency of the well placement of the model studied. In order to do this, a combined shear-thinning/-thickening model, the Unified Viscosity Model (UVM), is used. COMSOL Multiphysics is used in order to study the model, combining the fluid flow and mass transfer in one study, showing the interdependence of both physics transport phenomena. The results show how the influence of the polymer properties and the rock formation affect the recovery behavior. The particle tracing study allows us to determine the percentage of the chemical agent recovered in the producing wells. This paper shows how EOR agents works coupled with advanced numerical models in real-scale fields