Update of the Enchova Field 10-Well Subsea Production System
Authors: Reimert L.E. , Gray D.J. , Machado Z.L. 
Published: December 2007

The Enchova field template production system is now in the completion stages in the Campos basin offshore Brazil. This paper reviews Enchova development and summarizes the 10-well subsea production system. Design evolutions since the production system. Design evolutions since the concept first was disclosed are presented, as are the steps remaining to bring the template system on full production. production.

Introduction

The Enchova field development-about 120 miles (200 km) northeast of Rio de Janeiro in the Campos basinhas been one of the more important examples of marginal field development using early subsea production techniques. The second well drilled production techniques. The second well drilled surprised Brazil by showing the highest potential production rate known in the country. Eager to learn production rate known in the country. Eager to learn more about the newly discovered reservoir and at the same time increase the country's oil production, Petroleo Brasileiro S.A. (Petrobras) decided to Petroleo Brasileiro S.A. (Petrobras) decided to proceed in stages. Consequently, this first proceed in stages. Consequently, this first confirmation well was brought into production only 5 months after equipment was ordered (Fig. 1).

Phase 1 Phase 1 The drilling semisubmersible Sedco 135D was converted to a floating production platform for this first phase. Production flowed to the surface through a test tree suspended inside the blowout-preventer (BOP) stack and riser. Oil and gas were separated, and the gas was flared. Processed crude then was transferred through a floating hose to a nearby moored tanker. During this time, two more confirmation wells were drilled. Commercial shows prompted Petrobras to proceed to the next phase, prompted Petrobras to proceed to the next phase, which brought these wells on production (Fig. 2).

Phase 2 Phase 2 The second phase, more ambitious than the first, contracted another semisubmersible, Penrod 72, for conversion to a floating production platform. Like Sedco 135D, Penrod 72 was anchored over one well and brought crude oil to the surface through a BOP production tree. However, a second well was brought production tree. However, a second well was brought on production through a wet subsea tree at a record water depth of 610 ft (186 m). Crude oil flowed 1.7 miles (2.74 km) to Penrod 72 through a free-hanging flexible flow-line/riser system. The riser system included a control line umbilical for communication between the tree and Penrod 72. Processed crude from the two wells was transported through an 8-in. (203-mm) flexible flow-line/riser to a monobuoy tanker loading facility 2 miles (3.2 km) away. A second 8-in. (203-mm) flexible flow-line/riser was connected between Penrod 72 and Sedco 135D [a distance of 1.9 miles (3.1 km)] which permitted optional tanker loading facilities from both vessels.It is important to note that three new technologies - the subsea tree, the flexible production riser system, and the monobuoy tanker production riser system, and the monobuoy tanker facility-were introduced to offshore Brazil in this phase. Equally important is that Phase 2 production phase. Equally important is that Phase 2 production was brought on stream only 1 year after equipment was ordered (Fig. 3).

JPT

P. 1289