While the first subsea production system was installed in a shallow water environment (West Cameron field in Gulf of Mexico, by Shell in 55ft water depth, 1961), subsea development concept has been more synonymous with deepwater development. It has not been a development concept of choice for shallow water development in Middle East and Asia mainly due to the perception that it has higher life cycle cost and difficult to intervene.
Subsea production concept can be a competitive option vis-à-vis topsides production concept in certain circumstances. More often than not, project economics dictates that development capital expenditure (CAPEX) requires to be as low as practicable; and pre-investment in the initial phase of the project development needs to be carefully managed to minimize its impact on CAPEX and net present value (NPV). Subsea production system are inherently fit-for-purpose and provide an ideal opportunity for project owners to assess the potential of the particular field before deciding to proceed with full-scale development in the subsequent phase.
The fact that there is a large number of shallow-water subsea production systems installed and operated worldwide in the last 30 years provide sufficient track record, lifecycle cost and reliability data that could be used by field development and front end engineers in coming up with a feasible development concept with attractive NPV.
Subsea production system in a shallow water environment is a proven concept predominantly due to the following factors:
Provide alternative development option where fixed structures are not cost-effective:
a) Where development costs may not justify the CAPEX for a platform
b) Where brownfield expansion requires low well counts
Optimize drilling program:
a) If field reservoir areas are not reachable by deviated drilling from surface wells, producing hydrocarbon from multiple fixed structures might not be economically feasible
b) Subsea completion and production system offer better flexibility in term of field layout and well top-hole positioning
Accelerated development cycle:
a) Average 15-18 month to first oil from approval of Field Development Plan (FDP)
b) Capital Investment is returned in a more timely manner
Minimize cost on extended well testing-Longer well testing operations from a floating vessel with a lower cost are possible
Improved health, safety and environmental (HSE) performance - Removes people from offshore, potential to reduce visual and environmental impact
This paper will demonstrate that subsea development is a matured concept that can be attractive for shallow water applications.