Design of Marine Drilling Risers

MOCS is assisting Huisman in the development of a new Marine Drilling Riser (MDR) for different depths and pressure ratings. Huisman is a worldwide operating company with extensive experience in the design and manufacturing of heavy construction equipment for world’s leading on- and offshore companies. Huisman’s product range can be divided into six main categories: cranes, pipelay equipment, drilling equipment, winches, vessel designs, and specials, ranging from stand-alone components to highly engineered integrated systems.

Throughout the development of the new Marine Drilling Riser, analysis has been conducted on the riser string and details of a single joint.
The global string analyses are conducted in a static and a dynamic time domain environment. These environments are used to assess the:
– Subsea stack displacement when running through splash zone
– Maximum top tension when running to the required water depth
– Subsea stack displacement when landing it
– Operational envelope during connected, drilling and before emergency disconnect
– Maximum occurring stresses during connection, drilling and emergency disconnect
– Dynamic behaviour during a recoil incident
– Dynamic behaviour and maximum tension in case of a soft and hard handoff when waiting on weather
Envelope assessments are performed on the slip joint extension, maximum upper and lower flexible joint angle for the operational phase. Each assessment is done according to rules and regulations defined by e.g. API and DNV. For the elaboration of these analysis OrcaFlex and ANSYS are used as software packages where additional solving routines are programmed in different languages to improve efficiency and solving speed.
The local joint analyses are performed by means of ANSYS APDL and Workbench. For fast assessments beams and shells are used and solids are used when more detail is required. Assessments are performed on the maximum occurring stresses, dynamical excitation, buoyancy contact, local buckling (wrinkling) and global buckling.

Martijn BaasDesign of Marine Drilling Risers