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

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 custommade 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.

Comprehensive Guidelines for the Application of In-Situ Polymer Gels for Injection Well Conformance Improvement Based on Field Projects

“…Sheng (2011) mentioned that weak gels have a high resistance to flow but are still able to flow so can be injected deep into the reservoir. Han et al (2014) provided similar ideas and referred to WGs and CDGs as flowing gel processes. Furthermore, Song et al (2002) and Lu et al (2010) pointed out that WGs are oil-displacement agents in addition to their function as blocking agents.…”

“…2. Han et al (2014) have categorized a gel system as a weak gel if it has a storage modulus (G ' ) less than 1 dyne/cm 2 . 3.…”

Application of Polymer Based Nanocomposites for Water Shutoff—A Review

“…The two differ in their mechanism of enhancing recovery whereby polymer flooding maximizes penetration into low permeability zones that are saturated with oil while gel treatment maximizes entry into well swept high permeability streaks to shut off water [8]. Han et al [9] classifies the gel treatments into three, based on the conformance problem addressed-i.e., water shut off, profile modification, and in-depth flow diversion. Water shut off treatments are the focus of this review.…”

Self-adaptive preferential flow control using displacing fluid with dispersed polymers in heterogeneous porous media

“…Laboratory core experiments have demonstrated their EOR performance, and the excellent capability of dispersed polymers for EOR has been ascribed to the plugging and diverting effect (Bai et al 2007b;Wang et al 2012;Abdulbaki et al 2014;Han et al 2014;Wu et al 2015). Researchers figured out the importance of size matching between the particles and pore throats for plugging.…”