Problems in casing collapse

Abstract

The principal cause of casing collapse in the Bolivar Coastal field is compaction of the Miocene producing section and the resultant subsidence of the overlying sediments. The problems discussed concern methods of repairing wells with damaged casing as well as preventive measures being taken or proposed for new wells and workovers. Repairs to existing wells involve chiefly operational problems in placing re-liners, milling and sidetracking, and redrilling. Preventive measures are discussed both for wells completed in the compaction zone and those completed in sands below the compaction zone. These measures include the use of slip joints, corrugated casing, plastic pack, and stress relieving. Illustrations of the various methods of combating collapse are presented.