Planning Production Casing Strings for Deep Well Completions

ABSTRACT Production casing for deep high pressure corrosive environment wells requires special planning. The criteria by which production casing is chosen for wells shallower than 20,000' is quite different for deeper wells. If the worst case condition for internal pressure is a tubing leak, then the most accurate method of predicting shut-in tubing pressure must be employed. The use of the appropriate restricted yield materials is advisable in many high pressure completion systems, even in areas not normally associated with sulfide stress cracking problems. Uniaxial design analysis is not sufficient to adequately predict load condition in deep high pressure completion systems. A triaxial stress analysis should be performed to insure the yield strength of the material is greater than the worst case stress condition for the most cost effective size/material combination. A casing connection that has demonstrated performance under extreme combined loads should be chosen to insure the integrity of the production casing system.