Abstract
Enhanced oil recovery (EOR) in naturally fractured reservoirs presents significant challenges, particularly when addressing water production and the inefficiency of CO₂ displacement due to finger channeling. This research explores polymer-assisted CO₂ huff-n-puff processes to address these issues as a conformance control strategy. The motivation stems from the critical need to improve oil recovery while minimizing water cut and optimizing injected gas utilization in reservoirs, which is vital for the sustainability of oil extraction practices.The study employs a compositional reservoir simulator (CMG GEM) to design and analyse various scenarios of polymer-assisted carbon dioxide (CO₂) enhanced oil recovery. The methodology involves initial reservoir depletion for 589 days, followed by a one-month polymer injection phase, during which the polymer is allowed to set by shutting the well. Subsequently, a huff-n-puff process is conducted, iteratively increased from three to five cycles, with additional polymer injections introduced after the second cycle. Key parameters such as polymer molar ratio, reservoir porosity, permeability, gas-oil ratio (GOR), and gas production rates were evaluated to assess the effectiveness of this approach.
The results demonstrate a reduction in percentage water cut, gas production rate, and gas oil ratio, with a consequent increase in oil recovery factor when polymer conformance was introduced in the huff-n-puff process. These effects, therefore, highlight the potential of polymer conformance as a viable method to enhance CO₂ huff-n-puff in an enhanced oil recovery operation. A rigorous understanding of the physical processes influencing these operations was achieved, along with insights into the effects of various parameters on maximizing hydrocarbon recovery while effectively minimizing water production. These findings contribute to the growing knowledge on conformance control and provide valuable insights for optimizing oil recovery processes in naturally fractured reservoirs. There is also a belief that polymer materials used in enhanced oil recovery are cheap and eco-friendly, especially biodegradable and bio-based, environmentally friendly polymers. This also further reiterates its advantages and importance in this research.
Keywords: Enhanced oil recovery; carbon dioxide huff-n-puff; polymer conformance, polymer injection, oil reservoir, gas-oil-ratio, water cut.
| Date of Award | 1 Jul 2025 |
|---|---|
| Original language | English |
| Supervisor | Jebraeel Gholinezhad (Supervisor) & Oghenovo Okpako (Supervisor) |