Assessing the Riser Concepts for a Deepwater FPSO

With oil and gas reserves moving into deeper waters Floating Production Units (FPUs) have been widely used for production purpose. Selection of FPU for deepwater field development is mainly governed by factors like water depth, location of field, environmental conditions, deck space requirements, storage requirements and offloading requirements etc. Amongst all the available FPU alternatives, ship shaped FPSO has dominated the concept selection and are generally used in marginal and remote fields lacking pipeline infrastructure. Selecting riser concept for FPSO stationed in deepwater has posed challenges due high hydrostatic pressure and large vessel payload. The most common riser concepts for aforementioned are free hanging flexible riser, Steel Catenary Riser (SCR) and Hybrid Riser Tower (HRT).The condition is worsened if besides deepwater, FPSO is also stationed in harsh environmental conditions. This is due to large offsets and dynamics of FPSO which are directly transferred to the riser's base. To cope up with this situation offshore industry has focused on concepts like Steel Lazy Wave Riser (SLWR), Single Hybrid Riser (SHR) and Buoyancy Supported Riser (BSR).