An alternate approach to downhole corrosion mitigation

Surface casing of the oil wells can cause serious hazards and possible blowout as a result of early corrosion. In different areas in the world, surface casing collapses as a result of downhole corrosion, casing cracking, and rupture under high-pressure-corrosion. Surface casings or conductor pipes cannot be excavated deep for repair because of safety concerns. Corrosion problems of the surface casing result from non-fined manufactured joints, presence of salt water in some formation beds, and the cement section that isolates formation from the casing. In the shallow part of the casing, corrosion can result from either local or areal electrochemical reaction. Since cement is an isolator between casing and formation, its presence and composition is crucial for the casing protection. In this paper, possible cement composition that mitigates casing corrosion will be discussed. Also presented will be corrosion tools that can clearly detect the defect in cement jobs.