Geochemical Modeling of Low Salinity Polymer Flooding for Carbonate Rocks

The demand for global energy has been continuously increasing, and the oil and gas (O&G) industry is a significant supplier of energy required to meet this demand. However, the industry faces challenges due to regulatory constraints and exploration complexity, which have made it necessary to maximize oil recovery from existing fields. Enhanced Oil Recovery (EOR) techniques have shown great potential in increasing oil recovery from reservoirs that were produced by conventional primary and secondary recovery methods. Chemical Enhanced Oil Recovery (cEOR) techniques, specifically Polymer flooding, have proven valuable in improving the macroscopic sweep efficiency and changing rock and fluid interactions at a reasonable technical and economic cost. To appropriately select a suitable polymer, it is essential to understand the impact of diffusion, polymer adsorption, and geochemical interactions between the polymer, brine, and rock phases. The main objective of this study is to propose a mechanistic model that captures the physicochemical aspects of polymer flow in porous media through a geochemical perspective using a coupled reservoir flow and geochemical numerical simulator (MRST-IPhreeqc simulator) for applications in carbonate rocks. The study developed a mechanistic model using MRST reservoir flow and the IPhreeqc geochemical simulator, with the MRST polymer module modified to model key parameters such as polymer viscosity, adsorption, IPV, RRF, hydrolysis, and shear effects. Surface Complexation Modeling from IPhreeqc was integrated to model Indiana limestone carbonate rocks and introduced a polymer species of ATBS sulfonated polymer for interaction within the MRST simulator for Low Salinity Polymer (LSP) flooding paradigm. The adsorption equilibrium is captured through thermodynamic reactions and flow equations. The updated simulator was validated against experimental tests for carbonate rocks. The results prove the simulator’s effectiveness in modeling the main mechanisms of LSP. This study offers insights into geochemical, reservoir flow, and adsorption in polymer flooding. The integration of geochemical factors is crucial for optimizing polymer flooding in the Middle East’s harsh carbonate reservoir conditions, enhancing regional oil recovery.