A Hole in Your Pocket; Mitigating Corrosion Perforations of Well Casings in Corrosive Formations with Advanced Technology Epoxies

Abstract

!!paper is an overview of coated and non-coated well casings in corrosive formations. Failure trend studies of externally un-coated well casings indicate a prevalence of external casing failures due to corrosive formations. Some casing failures have been documented in as little as twenty-four months. Well casings coated with advanced technology epoxies have improved the service life of these wells significantly. This paper describes the key learnings from these applications. ! Current successes in hydraulic fracturing techniques have lead to an extraordinary increase in drilling activity around the world. This recent boom in drilling activity has caught the attention of the general public and government regulators alike. One concern of particular interest is the use and protection of fresh water resources. Modern completion techniques require large amounts of fresh water to fracture hydrocarbon producing zones. There is also growing concern from the general public about completion chemicals and production fluids potentially contaminating freshwater sources. Maintaining casing integrity is essential to oil and gas production as well as protecting freshwater zones. Historically, Operators have employed several methods to isolate wellbores and production fluids from freshwater zones. Many of these protection methods have been used with differing amounts of success depending on casing design and metallurgy, cementing practices, wellbore geology and numerous other factors. One isolation method that is often overlooked is protective coatings for the externals of well casing. !coatings have commonly been used in the Oil & Gas industry for decades as the first line of defense against corrosion. Coatings are known to be an effective and economically efficient method for protecting metal structures against the effects of corrosive environments. They are used on everything from the rig floor to pipelines and just about everything in between. Why is it then, that we overlook protective coatings as a corrosion control method for well casing? Well casing is often exposed to the following corrosive conditions: ! ∞ Microbiologically-Influenced Corrosion (MIC)