Scenario Evaluation for Subsea Production System

Scenarios for a subsea production system are evaluated considering technical feasibility, operational reliability and financial return for the investment. A case study based on an offshore gas field is adopted as well as three associated subsea production scenarios in order to perform the relevant analyses which could lead to the recommendation of the best option. The field is located at a distance of 160 km from the Brazilian coast at the water depth of 500 m, decreasing to 180 m at 140 km from the coast and then progressively up to the beach. Three different scenarios for the subsea production systems are proposed. Semi-submersible (scenario 1) distant 160 km from the coast at water depth of 500 m and the subsea arrangement constituted of eight satellite wells. Jacket platform (scenario 2) distant 140 km from the coast at water depth of 180 m. Scenario 3 is a Subsea to Beach system (without platform). Initially, general arrangements for the subsea production systems are implemented to establish the respective equipment locations. Flow assurance has been considered in order to avoid hydrate formation which could block the lines and stop production. Risk assessment for the proposed subsea production systems are performed using fault tree analyses. The selected top event is either total or partial production loss. Finally a cost analysis is performed for the system life cycle, including both capital (CAPEX) and operational (OPEX) expenditures. Based on these assessment analyses the best arrangement for the subsea production system is recommended.