Optimization of Enhanced Oil Recovery using Hybrid CO2-Nanoparticle Foam Flooding in Depleted Reservoirs

Project Abstract

This study presents a comprehensive evaluation of a hybrid CO2-nanoparticle foam flooding approach to enhance oil recovery in depleted reservoirs, integrating experimental, numerical, and techno-economic analyses to establish a viable field-scale implementation framework. The core objective is to quantify the incremental oil recovery, optimize foam stability and mobility control, and understand the interactions among CO2, surfactants, and nanoparticles under reservoir conditions, including high salinity, high pressure, and elevated temperature environments. Laboratory experiments were conducted to synthesize and characterize stable foam formulations using a range of nanoparticles (silica, alumina, and silica-coated magnetic particles) and surfactants compatible with CO2-rich brines. Coreflood experiments in carbonate and sandstone plugs simulating depleted reservoirs assessed displacing efficiency, trapping mechanisms, relative permeability alteration, and resistance factors at representative reservoir temperatures (60–120°C) and pressures (20–40 MPa). The results demonstrated that hybrid foam systems significantly reduced gas mobility, lowered CO2 channeling, and enhanced oil displacement efficiency by promoting favorable interfacial rheology, wettability alteration, and segregated transport pathways that impede gas breakthrough. A dynamic reservoir model incorporating capillary desaturation, foam generation kinetics, gas-liquid partitioning, and nanoparticle transport was developed and validated against experimental data, enabling sensitivity analyses of foam quality, gas slippage, salinity, nanoparticle concentration, and injection rate. The modeling framework was employed to simulate field-scale scenarios, revealing substantial oil recovery gains with manageable adverse effects on injection pressure and foam stability when optimized parameters—foam quality between 0.2 and 0.6, nanoparticle concentration in the range of 0.01–0.1 wt%, and CO2 slug sizes aligning with reservoir heterogeneity—were implemented. Economic viability was evaluated through a discounted cash flow analysis, accounting for CO2 sourcing, nanoparticle synthesis, surfactant consumption, surface facility adjustments, and potential CO2 sequestration credits. Sensitivity analyses highlighted that the most significant economic drivers are CO2 availability, foam longevity, and incremental oil production rate, while the principal technical challenges include nanoparticle retention near the wellbore, long-term stability under complex brine chemistries, and scale-up from corefloods to heterogeneous reservoirs. The study proposes a delineated workflow for field deployment, including a screening framework to identify suitable reservoirs, a pilot design with monitoring plans for foam in-situ behavior, and risk mitigation strategies addressing phase separation, emulsification risk, and environmental considerations. The findings indicate that the hybrid CO2-nanoparticle foam system can markedly improve sweep efficiency and ultimate oil recovery in depleted reservoirs, while maintaining acceptable operational risks when designed with robust particle selection, compatible surfactants, and temperature- and salinity-tolerant formulations. This work contributes a quantitative, integrated methodology for assessing foam-assisted CO2 EOR schemes, offering a pathway toward scalable implementation and informed decision-making in mature oil fields facing declining production.

Project Overview

What This Project Is About

---

This project looks at ways to recover more oil from old wells by combining two approaches: using CO2 gas to push oil and tiny particles that help foam to block high-flow paths in the rock. The goal is to use a hybrid foam system that travels through depleted reservoirs more effectively and reduces the amount of oil left behind.

---

---

The Problem It Addresses

---

---

---

Objectives of the Project

---

1. Review how current enhanced oil recovery (EOR) methods work and where they fail in depleted reservoirs.
2. Explain what CO2-nanoparticle foam is and how it could improve oil displacement.
3. Model the flow of the hybrid foam in simple rock-like systems.
4. Assess potential benefits, costs, and environmental considerations of the method.
5. Suggest practical guidelines for laboratory testing and pilot studies.

---

---

What You Will Do Step by Step

---

1. Study background literature on CO2 flooding and nanoparticle-stabilized foams.
2. Define a simple experimental setup to test foam stability and oil recovery in core samples.
3. Run small tests varying foam composition, gas flow, and rock properties.
4. Collect data on oil recovered, pressure behavior, and foam stability.
5. Analyze data to identify trends and optimal conditions.
6. Compare results with traditional methods to evaluate improvements.
7. Discuss practical challenges and safety considerations.
8. Prepare a concise report of findings and recommendations.

---

---

Expected Outcome