Optimization of Enhanced Oil Recovery in Heterogeneous Reservoirs Using Hybrid Surfactant-Polymer Nanofluid Flooding

Project Abstract

This study proposes a novel hybrid surfactant-polymer nanofluid flooding approach to optimize enhanced oil recovery (EOR) in heterogeneous reservoirs, addressing the challenges of mobility ratio mismatch, capillary trapping, and low sweep efficiency typical of conventional EOR methods. The research integrates experimental, numerical, and theoretical analyses to evaluate the performance of surfactant-nanoparticle assemblies and polymer-nanofluid systems under reservoir-relevant conditions, including high salinity, variable temperatures, and rock-fluid interactions. A bespoke nanofluid formulation combines a low-surface-tension surfactant with functionalized nanoparticles to stabilize microemulsions and modify interfacial rheology, while a viscoelastic polymer is engineered to withstand adsorption and shear degradation. The abstracted mechanism hinges on interfacial tension reduction, favorable rheology modification, and controllable wettability alteration to promote displacing efficiency in heterogenous pore networks characterized by wide permeability contrasts and multiple natural fractures. Laboratory core flooding experiments across sandstone and carbonate matrices quantify oil recovery improvement, capillary-entry pressure reduction, and breakthrough behavior under a range of flow rates, salinities, and temperatures. Interfacial tension measurements, contact angle assessments, and zeta potential analyses illuminate interactions among oil, rock, surfactant, polymer, and nanoparticles, guiding the optimization of circular- and radial-flow configurations. A coupled upscaling framework, employing pore-network modeling and continuum-scale reservoir simulation, translates microscale heterogeneity and time-dependent nanofluid transport into field-scale predictions of oil recovery, pressure response, and injectivity. Sensitivity analyses identify critical parameters, including nanoparticle concentration, surfactant dose, polymer molecular weight, salinity tolerance, and adsorption losses, enabling robust design of injection strategies that minimize environmental footprint and operational costs. The study also investigates the sustainability and economic viability of the hybrid formulation by performing lifecycle assessments and techno-economic analyses, comparing the proposed method against conventional chemical EOR, polymer flooding, and low-salinity waterflooding. Results demonstrate notable gains in ultimate oil recovery, particularly in zones with low permeability streaks and high residual oil saturation, where traditional methods underperform. The nanofluid enhances sweep efficiency by stabilizing emulsions, reducing interfacial tension to the order of 10-3 to 10-4 mN/m, and sustaining favorable mobility control through viscoelastic polymer behavior and nanoparticle-assisted wettability alteration. Field-pertinent guidelines for implementation are developed, including optimization of slug size, cycle timing, well placement, and monitoring strategies based on real-time data analytics. The research advances the understanding of synergistic interactions in hybrid nanofluid systems and provides a scalable methodology for deploying next-generation EOR solutions in heterogeneous reservoirs, with potential implications for extending field life, improving recovery factors, and reducing the carbon intensity of hydrocarbon production. The outcomes contribute to a transferable framework for evaluating complex nanofluid-assisted EOR technologies under diverse reservoir settings and operational constraints.

Project Overview

What This Project Is About

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The project explores how we can improve oil recovery from rock formations that are not uniform in their properties. It looks at using a special mix of tiny particles and chemicals carried in water (hybrid surfactant-polymer nanofluid) to help push more oil out of difficult-to-access areas. The goal is to understand how this mixture behaves in real rocks and how it can be optimized to work better in varied reservoirs.

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The Problem It Addresses

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Objectives of the Project

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1. Review existing oil recovery methods and the role of nanofluids, surfactants, and polymers.
2. Explain how rock heterogeneity affects oil displacement.
3. Design a hybrid nanofluid formulation suitable for heterogeneous rocks.
4. Assess the mobility control and oil-wetting changes caused by the treatment.
5. Evaluate environmental and economic feasibility considerations.

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What You Will Do Step by Step

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1. Study background literature on EOR, nanofluids, and polymer flooding.
2. Collate rock and fluid property data relevant to heterogeneity.
3. Develop a simple experimental setup or numerical model to test nanofluid behavior.
4. Prepare and test a hybrid surfactant-polymer nanofluid formulation in simulations or bench experiments.
5. Analyze how the formulation changes oil recovery under different rock conditions.
6. Assess cost, scalability, and environmental implications.
7. Summarize findings and discuss practical guidelines for field pilots.

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Expected Outcome