Controlling corrosion in production tubing is essential for maintaining production and for preventing loss of well control. Materials for use downhole have to meet criteria for corrosion resistance and also mechanical requirements. The potential corrosion rate can be estimated and the risks of sulphide stress corrosion cracking (SSCC) assessed on the basis of the anticipated environmental conditions and flow regime. Material options for tubing can then be consid- ered on the basis of published corrosion test data and also field experience. Candidate materials may be tested under the precisefield conditions expected in order to ensure that overconservative choices are not made. Corrosion inhibitors, coated carbon steel, andfibre reinforced plastic tubing have temperature, pow regime, and mechanical limitations. Specific cowosion resistant alloys (CRAs) have environmental limitations with respect to temper- ature, hydrogen sulphide, and chloride content. Details offeld experience with all of these material options are given. There exists a large amount of experience with CRAs for downhole applications. Correctly selected CRAs have a good track record of service, even for hostile. H,S containing conditions. There are afew limited examples of CRA clad tubing. This product may be one that needs re-evaluation as it offers potential for economtc use of costly but effective CRAs.
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