Abstract
Assessment of well integrity has become more important for CCS and CO2-EOR as it has become apparent that wells represent the most likely migration pathway for CO2 to leave a CCS storage unit or a CO2-EOR reservoir. Although wells represent a migration pathway, they are also the best vehicle for employing technology monitoring CO2 injection and storage. This contradiction of being a potential migration path and key monitoring technology leads to a need to understand how monitoring wells may be similar or different in comparison to other types of wells with respect to migration risk. The maturation and completion US Department of Energy sponsored research projects presents an opportunity to assess the integrity of monitoring wells that have been exposed to injected CO2. This paper discusses an integrity assessment of two monitoring wells in an operating CO2-EOR flood in Mississippi, USA. It provides an early assessment of how monitoring equipment affects well integrity and isolation capacity. Each of the monitoring wells in this study were similarly constructed using both fiberglass and conventional steel casing. Each of the wells was instrumented with multiple monitoring technologies including, electrodes, pressure gauges, and temperature sensors on the outside of the casing. Control lines and cables were run from the surface on the outside of the long-string casing in each well to communicate with the monitoring equipment. A comprehensive logging, testing, and sampling program was developed to assess integrity in both wells. Ultrasonic well mapping was used to create radial maps of the location of cement, liquid, and gas behind the casing. Cement bond logging provided information on the casing-to-cement and cement-to-formation bonds for the long-string section. The logs showed that the monitoring equipment attached to the long-string casing is visible as continuous low acoustic impedance features and may represent a leakage risk. Cased-hole sidewall cores were collected and provided some validation of the log results and provide local information on the isolation capacity of the wells. The combination of information from the log data sets and cores was used to assess isolation capacity. The results of the study show that careful design and assessment of the materials used in monitoring well construction, the types of monitoring technology, and the location of monitoring technology within a well needs to be conducted with limiting migration potential and maximizing well integrity as objectives.
Recommended Citation
A. Duguid et al., "Well Integrity Assessment of Monitoring Wells at an Active CO2-EOR Flood," Energy Procedia, vol. 114, pp. 5118 - 5138, Elsevier, Jan 2017.
The definitive version is available at https://doi.org/10.1016/j.egypro.2017.03.1667
Department(s)
Geosciences and Geological and Petroleum Engineering
Publication Status
Open Access
Keywords and Phrases
Acoustic Impedance; Cased Hole; CBL; CCS; CO -EOR 2; Leakage; Risk; Sidewall Cores
International Standard Serial Number (ISSN)
1876-6102
Document Type
Article - Conference proceedings
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2024 Elsevier, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Publication Date
01 Jan 2017
