Modeling and Design of Steel Catenary Pipeline for Sardar-e Jangal Gas Field in Caspian Sea under Random Wave

Offshore petroleum production began in the shallow waters. As these reservoirs have been exploited mean while increasing of oil and gas demand, the petroleum industry has been moving to the deep waters. Whereas our country (Iran) has been located in fringes of Caspian Sea deep water, therefore study and research in this area is increasingly essential. Marine risers are the main components of the drilling and extraction of oil and gas in the offshore platforms. Hence the study of the riser lines under the specific environmental and loading conditions is mandatory to achieve optimal design of offshore oil platform. The movement of floating and semi-submersible rig causes the stress and displacement of the touchdown Point (TDP) in marine risers. Therefore, determining the exact response of steel catenary risers (SCRs) at the TDP is an important parameter to approximate the behavior of the riser. Also, it can be used to investigate the phenomenon of fatigue and corrosion caused by movements of risers in the touch down zone.In this paper, after obtaining the minimum wall thickness and diameter required by design codes according to the harsh climatic conditions, a steel catenary riser on soft clay in 700 m depth of water is modeled and analyzed using the commercial software OrcaFlex. The dynamic response of the riser is investigated. A fully 3D non-linear time domain finite element with a robust meshing technique has been applied to simulate the arbitrarily large deflections of the flexible from the initial configuration. A simple lumped mass element is used which greatly simplifies the mathematical formulation and allows quick and efficient development of the program to include additional force terms and constraints on the system. Finally, the proper marine riser thickness suitable for Sardar-e Jangal Gas Field in Caspian Sea has been proposed.

Keywords:

Steel catenary riser , Wall thickness , Touchdown point , OrcaFlex