2H modified and optimised the design of a prefabricated rigid jumper kit and provided Tullow with a solution that reduced procurement and fabrication time and costs.
FIELDS Jubilee REGION Offshore Ghana WATER DEPTH 1,200m
Background
Tullow Ghana’s Jubilee field is located in the West Cape Three Points block, offshore Ghana. The development consists of subsea production systems and SURF equipment tied back to an FPSO. Rigid well jumpers provide an interface for transporting fluids between the wells and the subsea structures.
Tullow wanted to fabricate and install new and replacement jumpers on the Jubilee field using prefabricated jumper kit left over from another project. Tullow contracted 2H to assess the suitability of the prefabricated rigid jumper kits and line pipe materials.
2H’s Role – Assessing Jumper Suitability
The 2H team started by reviewing jumper specifications to determine the suitability of the line pipe for jumper application. We performed strength and VIV analysis to confirm that the jumper design met the necessary design codes. We evaluated the existing water injection and production jumpers in the Jubilee field, then optimized the jumper shape and configuration to achieve a working jumper structure with the available equipment.
Execution
As part of the design activities, we performed a displacement controlled strength analysis and vortex induced vibration (VIV) fatigue analysis to assess the acceptability of jumper design. To overcome design challenges, we used metrology survey data of the jumpers to reduce conservativism in design, fabrication and installation tolerances, combined with the use of buoyancy modules to reduce jumper loads. We optimised jumper shapes and buoyancy distribution to minimise stress in the jumper and to reduce buoyancy module requirements. We defined VIV suppression strake requirements for each jumper to meet target design life using a VIV assessment we carried out using in-house software tools.
Results
2H provided the client with the working configurations for several jumpers. The final configurations did use the prefabricated kit, significantly minimising procurement and fabrication time and costs.
