Research and Development of Advanced Coiled-Tubing Construction and Performance

Abstract

This paper describes joint industry project DEA107, in which BP plc, Amoco, Eni SpA. Div. Agip, Scottish Enterprise Operations, and Japan Natl. Oil Corp. (JNOC) participated. Objectives of this project were to investigate and to report on the low-cycle fatigue phenomena of coiled tubing (CT), to present a rational fatiguelife prediction model for CT, and to develop an advanced CT which could be applied to CT drilling of deep wells. In this paper, the effect of various factors on the cyclic bending performance of parent CT materials is predicted in relation to ballooning and low-cycle fatigue phenomena; corrosion and low-cycle fatigue phenomena of CT after long-term exposure in a mud environment are discussed, followed by fatigue performance and improvement of circumferential joining techniques.A trial section of advanced CT of 2 3 /8-in. outer diameter (OD) and 0.190-in. wall thickness (WT) with a total length of 3,000 ft was manufactured by means of joining short lengths of seamless tubing using the amorphous diffusion bonding (ADB) technique. A CT drilling test at the JNOC Kashiwazaki test field in Japan was completed successfully using this advanced CT.