No abstract

No abstract

No abstract

No abstract

In a carbon dioxide (CO 2) enhanced oil recovery (EOR) operation, CO 2 is injected into a hydrocarbon reservoir to enhance hydrocarbon production. Much of this CO 2 is recycled for reinjection when the hydrocarbons are produced; however, a large amount is permanently stored in the reservoir. If a CO 2-EOR operation intends to claim CO 2 storage credit for this stored CO 2, it needs to demonstrate that the CO 2 is safely stored in the subsurface by strategically deploying monitoring technologies. For the operation to maintain profitability goals, these monitoring technologies also need to be cost-effective. If the safety of the CO 2 storage is demonstrated, the project will be classified a carbon capture, utilization, and storage (CCUS) project. The main goal of CO 2-EOR is oil production, not CO 2 storage. Because CO 2-EOR originated as an oil production technique, the EOR process is subject to a less stringent regulatory environment than CCUS projects. These differences in the CO 2 storage accounting and the regulatory environment mean that CO 2-EOR projects need to demonstrate the long-term containment of CO 2 within the reservoir with additional monitoring in order to claim any CO 2 emission credits. Converting a CO 2-EOR project to a CCUS project requires a tailored site-specific approach. The methodology employed will differ from project to project due to differences in project risk, geology, operations history, and regulatory environment. This paper takes the CO 2-EOR Weyburn-Midale Field (WMF) as a case study to rank monitoring strategies that may be required to shift the WMF from CO 2-EOR to CCUS. This study consisted of an in-depth review of the identified risks, the potential leakage pathways, various regulatory requirements, and the already deployed monitoring techniques. The goal was to develop a risk-, economic-, and regulatory-based monitoring technology ranking system that is suitable for the WMF. While specific to the WMF, the methodology presented here can be adapted by other CO 2-EOR operators who endeavor to demonstrate that the non-recycled portion of the CO 2 injected into the formation(s) by their project(s) is permanently stored.