Lessons Learned From Recent CCS Well Construction Projects

Abstract

Carbon Capture and Storage (CCS) wells are constructed using standard oilfield equipment and generally supervised by oilfield personnel; however, the goals of CCS wells are much different than a typical oil and gas well. The standard to which wellbore integrity is held in CCS wells is higher than the standard for a conventional oil and gas well because they are regulated by the US EPA as part of the Underground Injection Control (UIC) program. The methods used for evaluation are more sophisticated as well including detailed logging and integrity characterization. From the initial well planning and all the way through well construction process it has to be emphasized that the goal of the well drilling is to drill a hole that will facilitate a successful cementing operation; i.e., as straight and as close to gauge as possible. A slight change in penetration rate or different pump pressures can adversely affect the borehole as well as the cement integrity for the entire well.

Recent experience with CCS well construction highlights challenges. Three CCS monitoring wells were constructed recently as part of a project called “Establishing an Early Carbon Dioxide Storage (ECO₂S) Complex in Kemper County, Mississippi” (Project ECO₂S). UIC requirements specify that the long-string casing be cemented to surface, to simplify cementing operations each well was cemented in a single stage. Single-stage cementing required balancing the slurry properties and density with set cement properties and CO₂ resistance. The integrity of each of the wells was assessed considering the geologic setting using open-hole logs, the hole conditions, casing setting and centralization details, cement pumping data, and cased-hole integrity logs.

Two wells had cement returns surface. One well lost much of the cement to the surrounding formations (no returns to surface). Technical contributions of this work include how detailed logging can be used to identify contaminated cements, how cement operations and hole conditions can be designed reduce poor cement outcomes, how to balance operational needs for successful cementing with long term requirements of the well and how cultural differences in planning and operations between oil and gas and CCS can affect integrity. Overall, the results of the Project ECO₂S well integrity assessment provides lessons learned to construction of CCS and other wells that may need to be constructed to withstand CO₂ exposure including CO₂-EOR wells.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018