Subsea jumper is an important component of underwater production system. In deep water, vertical M-shape rigid jumper with simple installation is mostly used. Fatigue damage assessment is an important part in the design of M-shape jumper, which usually includes three aspects: vortex induced vibration fatigue, thermal cycle fatigue and fatigue during transportation and installation. This paper mainly introduces the causes, simplified calculation method and analysis process of vortex induced vibration fatigue and thermal cycle fatigue damage. An engineering example is given to illustrate above methodologies.
Jumpers are important components of subsea oil and gas production systems, which are used to connect subsea structures, such as manifolds, trees, pipeline end termination (PLET), pipelines and riser bases via subsea connectors.
Based on API RP 17R (2015), subsea jumpers are divided into rigid jumper and flexible jumper. Flexible jumper is designed and manufactured by a few international production suppliers, which is connected with Flexible pipe connector and specified gooseneck. It has the advantages of high structural flexibility, excellent fatigue design life and unlimited length. The disadvantages are high material cost, long procurement period and limited ROV access space. The rigid jumper is welded by conventional carbon steel pipe or clad pipe. It stands out due to its common material, convenient construction and installation, large ROV access space and low cost. The vertical M-shape jumper structure with good adaptability is mostly used for deep-water jumper. Typical schematic diagram of rigid jumper and flexible jumper are shown in Figure 1 and Figure 2 respectively.
Fatigue damage assessment is an important part in the design of deep-water M-shape jumper. It is necessary to numerically calculate or reasonably predict the fatigue damage caused by various factors to verify whether it can meet the requirements of design life. If not, appropriate mitigation measures need to be considered to reduce fatigue damage, such as adjust jumper configuration, or add VIV strakes, etc.
