Service Conditions and Current R & D Situation of Oil Tubing and Casing（Part Ⅱ）

Taking the actual circumstances of oil fields into consideration, domestic OCTG manufacturers and the end-users have been closely cooperating in R & D activities, which has tremendously speeded up the localization pace of OCTG production, and brought about radical improvement on production capacity, types and sizes as well as quality of the oil tubing and casing. Briefed here in the article are mechanical and environmental service conditions of tubing and casing columns and types of and causes for failures of the oil tubing and casing. Also presented are the progress and current situation relating R & D of oil tubing and casing products. It is proposed that development of non-API steel grade tubing and casing with premium thread connections and spe-cial-purposed OCTG should be strengthened. Critical technical issues that need to be solved are pointed out. Finally it is emphasized to build up relevant evaluation criteria and methods in a rather scientific way.