Paper: Well Casing Cathodic Protection Evaluation Program In The Spraberry (Trend Area) Field

Pioneer Natural Resources is currently undertaking a study of well casing failures in the Spraberry (Trend Area) Field located primarily in Midland County, Texas. Failure trend studies indicate a high incidence of external casing failures in the San Andres formation, a known saltwater-bearing and saltwater disposal formation that generally has substantial H2S content. Several well casings were selected as candidates for down-hole inspection logs to determine if cathodic protection could be a viable solution to the external corrosion problem. "Test" cathodic protection systems were installed and down-hole tools were utilized both prior to and after energizing the systems to assess the external condition of the well casing. Anodic/cathodic areas and axial current flow patterns identified on the logs were correlated to previously conducted cement bond logs, casing inspection logs and gamma ray/neutron logs as well as areas of externally coated casing. Based on logging results and economic evaluation, implementation of a cathodic protection pilot project commenced on November 27, 2001