(754c) Optimization of EOR in Horizontal Fracturing through Injection of Recovered CO2 from Amine Sweetening Process

Rajib Mukherjee, Sepehr Arbabi*

Department of Chemical Engineering, University of Texas Permian Basin, TX 79762

*corresponding: sepehr.arbabi@utpb.edu

Abstract

Injection of CO2 into a suitable reservoir has long been practiced for co-optimization of enhanced oil recovery (EOR) and CO2 sequestration [1]. Recently, economic optimization of EOR through injection of gas, which is otherwise flared, to stimulate oil production as well as sequestration of the injected gas have been studied [2]. The injection process is generally carried out in multiple huff and puff stages. Even though EOR through gas injection may result in capture of the gas in-situ, a substantial amount of the injected gas flows back with production of the oil and gas from the wells. It has been found that when CO2 is used for EOR, the amount of CO2 increases significantly in the produced gas following EOR process. The CO2 can be recovered during natural gas processing through amine sweetening process. In this presentation, EOR through injection of acid gas recovered during gas processing have been studied to understand the economic and environmental implications of recovered acid gas injection in shale oil developments, which is otherwise vented. A surrogate model-based optimization is proposed to integrate the development of a shale oil and gas reservoir along with EOR projects. The framework optimizes decisions such as drilling scheduling, workover of depleted production wells, natural gas processing unit, location of injection sites, injection rates, and duration of EOR operations. The EOR is implemented in the Bakken formation through a reservoir with 10 wellpads and a modular amine sweetening processing unit. EOR in the subsurface is modeled through compositional reservoir simulation with its production functions scaled and utilized as input to the simulation for gas processing on the surface. It is found that and as much as 50 % of the injected gas can be reused in subsequent stages of EOR. Results also show the expected enhancement in oil production and recovery factor. Sensitivity analysis was also performed to find the importance of different operational variables on the EOR efficiency.

Keywords: carbon management, process design and development, carbon capture & storage, environmental sustainability

[1] Wang, X., van’t Veld, K., Marcy, P., Huzurbazar, S., & Alvarado, V. (2018). Economic co-optimization of oil recovery and CO2 sequestration. Applied Energy, 222, 132-147.

[2] Calderón, A. J., & Pekney, N. J. (2020). Optimization of enhanced oil recovery operations in unconventional reservoirs. Applied Energy, 258, 114072.