Fitness-for-service Assessment Of Drilling Pipe And Its Sortware Development

Fitness-for-service assessment of drill pipe is the quantitative evaluation for the drill pipes containing defects to determine whether they can be used and how they should be used continually. This paper summarizes the research and development situation on the following aspects: the significance and the basic theory of fitness-for-service assessment of drill pipe, the methods dealing with the undetermined problems during the assessment, prediction for fatigue service life of drill pipe, and so on. It discusses the calculating methods of mechanical and material performance parameters. The functions of developed fitness-for-service assessment software of drill pipe: (1) safety status assessment of damaged drill pipes (FAD assessment and limit defect dimension curve); (2) fatigue service life prediction of drill pipe; (3) safety reliability and risk assessment of drill pipe; (4) operation limits of drill pipe. Full-scale fatigue test of drill pipe and borehole tests of drill pipes containing defects prove the reliability of assessment methods and software posed in this paper.Utilizing the computer technology and combining the research results of material science and mechanics, this paper discusses the fitness-for-service assessment technology of drill pipe, and fills up the empty of this field in China. This technology has the magnificent economic and social benefits for oil and gas industry.