ABSTRACT

With the development of marine oil&gas exploration technology, flexible risers are frequently used in marine engineering.The paper introduces key procedures and measuring methods of the off shore experiment of this new-type non-metallic composite flexible risers. It inspects the actual experimental operating performance, anti-tension and anti-compression strength, reliability, etc. Results indicate that non-metallic composite flexible risers perform well in anti-bending and anti-compression. It present an atypical catenary shape in water. Bending curvature near the touch down point increases obviously; the top tension is effected by bulge process and wave-current. The bigger the internal pressure is, the smaller the tensile force is. Because of buoyant force, the tensile force along the axis decreases gradually; the internal pressure shared by skeleton layer among all the layers is the largest, arriving at 54.5%.

INTRODUCTION

In recent years, there are more and more oil-gas explorations and production activities. Applying new technology and developing present technology are becoming the theme of modern ocean engineering field. The increase of world petroleum industry and frontier of technology innovation are gradually depending on oil and gas exploitation in deep water (Krishnan, Asher, Kan, and Popelar, 2016). Deep-sea risers are the key parts in connecting subsea production systems and surface unit. In structural shape, deep-sea risers can be divided into Steel Catenary Riser(SCR), Top Tension Riser(TTR), Flexible Riser and Hybrid Riser (Dumitrescu, Pulici and Trifon, 2003). The development of flexible risers may be dated back to late 1970s. Although it started late, it developed promptly. High-rigidity spirals inside the compound structures can strengthen metal layer to guarantee density and the low-rigidity polymer sealant can ensure the integrity of the fluid. In the outside and inside loading conditions, these layers can glide mutually to ensure that flexible risers are equipped with the feature of low warp rigidity (Bectarte and Coutarel, 2004). Besides, spirals can be replaced by various materials to strengthen metal layers in order to improve and enhance mechanical properties. Because of these features, flexible risers are becoming the focus of risers worldwide in recent years. In the area of riser laying technology, the experiment of marine risers were conducted through special experimental equipment including pipelaying vessel, etc. Due to sea current and waves, the progressing of pipelaying vessels will lead to the change of pipeline stress, therefore various riser laying methods are formed. The forms mostly used are S-Shaped laying(Baker and McClure, 2002), roll-shaped laying (Choi, 1999), J-shaped laying (Féret, and Bournazel, 1987), trailer-laying (Li, Zhong, Jiang, He, and Sun, 2016), etc. The paper depends on the actual and correct evaluation of system performance in the process of experiment through roll-shaped laying. This evaluation not only explores the details of technology and the function limits of every designing, but also analyzes the reliability of the designing and the interface requirements, and the cost. The paper introduces the process of new non-metallic composite flexible risers installation experiment, analyzes the measured data and confirms the posture, stress and law of motion.

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