CO2 Injection Wells:
Class II Wells
(required for CO2 EOR Service)
vs.
Class VI Wells
[required for CO2 storage (geological storage) objectives]
Since more and more companies are evaluating mature oil fields, around the world, for their potential for CO2 enhanced oil recovery (EOR) and/or CO2 geosequestration projects, one should keep in mind that those mature oil fields may have wells that have compromised well integrity concerns due to application/age of wells and operating history, etc. In addition, these mature oil fields may have many legacy wells that may have been improperly plugged and abandoned providing a potential conduit for escape of reservoir fluids to groundwater aquifers or to the surface. Therefore, after one has selected one or more mature oil fields, in the region of interest, that meet one’s selection criteria from geology and production/reservoir perspective, one should evaluate those selected oil fields from a life cycle well integrity perspective, to assure that injected fluids will remain confined to the target injection intervals and not pose a risk to human health and the environment.
The high-level and seasoned well integrity consultants of A&A Consulting Team are available to conduct due diligence, including, but not limited to, the following:
- Evaluate the current status of wells and determine which existing wells have adequate well integrity to meet fluid (CO2) injection standards (from a life cycle well integrity perspective)
- Determine which wells will require workover(s) to enable these wells to meet the regulatory and well integrity requirements for fluid (CO2) injection service
- Develop drilling and completion programs for new and/or infill wells
Although presently the well evaluation objective may be for CO2-EOR service only, but looking down the road, one may want to do the evaluation for both CO2-EOR service as well as for CO2 storage (geological sequestration) objectives. Since the well construction and regulatory requirements are much more stringent for Class VI wells [required for CO2 storage (geological sequestration) objectives] as compared to Class II wells (required for CO2-EOR service), with an increased emphasis on materials of construction (tubulars) and CO2-resistant cements to address the long-term corrosive characteristics of CO2.
The expertise and experience of the high-level and seasoned well integrity consultants of A&A consulting Team has been focused on Life Cycle Well Integrity (that covers all phases – drilling / operations / interventions / plugging and abandonment) for all types of wells – including Class II wells (required for CO2-EOR service) and Class VI wells [required for CO2 storage (geological sequestration) objectives]. A&A Consulting Team’s technical excellence combined with a deep understanding of regulatory and environmental aspects (with impacts on potential liabilities during an oilfield property acquisition / transfer) will be of critical value to our client’s oilfield evaluation and acquisition project teams.
A few examples of the recent work performed by the high-level and seasoned well integrity consultants of A&A consulting Team are listed below:
- Conducted evaluation of existing water injection wells for conversion to CO2-EOR service in an active oilfield. Focus of evaluation was to determine whether these wells are mechanically sound to maintain their well integrity during CO2 injection and will meet regulatory approval for service as CO2-injection wells in CO2 EOR project. Review included: Well construction, drilling and completion details, materials of construction – tubulars and cements, past performance history including any well interventions/workovers/conversions, etc. along with injection performance history.
- Conducted evaluation of existing wells (both producers and injectors) to assess risks related to well integrity concerns and potential risks from an environmental liability perspective (for the purpose of oil field property acquisition).
- Presented SPE Webinar “Life Cycle Well Integrity of CO2 Storage Wells: Engineering Imperatives for Success”.
- Presented SPE Section Lecture on “Comparative Summary of Conventional O&G Injectors, CO2-EOR Project Injectors, and CO2-Storage Project Injectors”.
- Prepared Technical Report “Well Engineering and Injection Regularity in CO2 Storage Wells”, for IEAGHG, UK. A major focus of the Report was to incorporate lessons learned/knowledge gained from CO2 EOR operators from well integrity and injectivity perspectives and transfer this knowledge to maintaining life cycle well integrity of CO2 storage wells.
To put the high-level and seasoned geology, reservoir, Production, and well integrity consultants, and other subject matter experts (SME), of A&A Consulting Team to work on your company's challenging oilfield evaluation and acquisition, CO2-EOR and/or CO2 geosequestration, projects, please Contact Us.
