Carbon Footprint and Energy Intensity Assessment for Enhanced Oil Recovery (EOR) Based on Polymer Injection: A Colombian Case Study

Abstract

Abstract Chichimene is an oil field located in the Colombian eastern basin. Since 2014, enhanced oil recovery (EOR) through the water injection process has been carried out successfully in part of this field. A polymer injection pilot was carried out over five injection patterns to optimize this process as a promising strategy for polymer-based EOR in challenging reservoir conditions with high temperatures and heavy oil. Polymer injection started in 2015 in the first injection pattern, and it was extended between 2018 and 2019 to five injector wells covering different areas of the oil field. 21.65 MSTB of polymer-augmented water were injected (approximately 7,000 t of polymer). At the end of 2022, the incremental oil production had reached around 4.9 MBbls (Million barrels of oil), and it is expected to increase up to 6.9 MBbls, resulting in a 9.84% incremental oil recovery factor. Considerable incremental oil recovery concerning the pilot patterns’ production baseline and notable carbon and energy intensity improvements were observed. Life cycle GHG (Green House Gas) emissions and energy consumptions associated with the crude oil production chain were estimated. Moreover, a suitable calculation tool of carbon footprint and energy intensity related to each stage of crude oil recovery by polymer injection processes was performed. The main contributions of GHG emission and energy consumption for the polymer-based EOR process analyzed were linked to lifting, oil dehydration, water clarification treatment, and Injection systems. The contribution of each stage in the total carbon footprint of crude oil production was calculated for the polymer flooding and compared with oil baseline production. The carbon footprint of implementing the oil recovery project was calculated for eight years. The results show that the carbon intensity of the crude oil baseline production in the five patterns is close to 20 kg CO2-eq/BO (barrels of oil) on average. Nevertheless, EOR by polymer injection decreases to 19.3 kg CO2-eq/BO. Regarding the energy intensity, the oil baseline production of the five patterns achieved 8.5 kWh/BO; however, the specific energy consumption in the EOR process by polymer injection decreased to 6.7 kWh/BO. The reduction is attributed mainly to energy use optimization in crude oil lifting and enhanced water re-injection with polymer. Furthermore, the carbon intensity reduction could lead to more than 3,200 t of CO2-eq avoided and improve the energy performance of polymer-based EOR by more than 20% concerning the baseline case. Nevertheless, a significant potential GHG emissions reduction of more than 4,000 t CO2-eq could be expected for the whole impact of this project in the Chichimene field.