The cost implications of using corrosion resistant alloys (CRAS) for downhole tubing are often significant when assessing the viability of corrosive high temperature fields. The possibility of using internal coating materials to protect carbon steel is therefore a viable option. As part of a progmrnme of work aimed at reducing well costs, the corrosion protection and mechanical properties afforded by a range of thin film coating materials have been investigated. The initial work involved evaluating the coatings corrosion protection in aggressive downhole conditions using high pressure autoclaves. Having established the ability to provide corrosion protection, the next stage was to assess the mechanical resistance to wireline abrasion and tool damage during downhole interventions. Problems associated with the use of thin film coatings downhole and recent concerns over the performance of CRAS are also discussed.
Kevwords: Internal coatings, production tubulars, corrosion resistant alloys, aggressive downhole conditions, oil and gas production, galvanic corrosion.