State-of-the-Art of In-Depth Fluid Diversion Technology: Enhancing Reservoir Oil Recovery by Gel Treatments

Abstract

Abstract In contrast to near-wellbore conformance control applications, polymer gels are applied in injector wells for reservoir scale applications for in-depth fluid diversion (IFD). Novel gel systems include weak gels, sequential injection for in-situ gels, colloidal dispersion gels, preformed gels, and microgels. The objective of an IFD process is to modify the prevailing reservoir inflow profile by gel treating the reservoir to significantly reduce effective permeability of high permeability zones that would otherwise dominate the water uptake. The weak gels or gel particles are treated as a flowing fluid and are custom-made for reservoirs with fractures or high permeability zones. The very weak gels form near the wellbore region, but continue to propagate into the reservoir. The gels eventually stop propagating deeper into reservoir due to the variation in pressure gradients and pore structures. The subsequent injection of fluids, water or chemical solutions, will redirect predominate flow paths to unswept reservoir zones, which improves oil sweep efficiency by waterflood (or chemical flood); thus, leading to enhanced oil recovery. The technology presents distinctive advantages to high-salinity and high-temperature reservoirs as compared to polymer flooding due to stability of cross-linked gel structures. This paper presents a state-of-the-art review of IFD technologies including weak gels, sequential injection for in-situ gels, colloidal dispersion gels (CDG), microgels, and preformed particle gels (PPG). Moreover, a solution to the challenges of IFD applications in high-salinity and high-temperature reservoirs is presented.