A large independent oil and gas producer 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. 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.

Subject
Electric current, Salt formation, Coatings, Voltage, Correlation, Cathodic protection, Cathodic current, Tools, Cathodic current density, Anodic current, Cement, External corrosion, Well casings
Keywords:
Axial current, casing inspection log, cathodic protection, down hole inspection, external casing failure, radial current density, well casing
Government work published by the Association for Materials Protection and Performance (AMPP) with permission of the author(s). Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2003
GOV
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