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Subsea completion systems
Drilling is not the only challenge to deepwater drilling economics. Current deepwater technology trends almost exclusively require huge discoveries and unprecedented production rates to ensure acceptable rates of return. Advancements in subsea completion technologies have the potential to reduce costs and improve economics.
Modular subsea completion systems
One method to reduce the high development capital expenditures associated with deepwater environments that is being explored (Fig. 1) is a modular system designed for easy retrieval to the surface using diverless techniques for:
- Repair and maintenance
- Process reconfiguration
- Equipment upgrade
The system reconfiguration will be accomplished by a workboat instead of a drillship. As a result, the cost of the reconfiguration, or “intervention,” could be reduced as much as $200,000 per day compared with systems accomplishing similar functions. This reduction in capital expenditures associated with intervention is expected to make many smaller reservoirs economically viable.
Three-phase pumps have been used with limited success to pump deepwater production to separation facilities. However, one characteristic of the deepwater Gulf of Mexico (GOM) is the significant topographic relief, occasionally reaching 1,000 ft in one 9-sq-mile lease. Such relief results in subsea pipelines acting as separators. As a result, severe slugging phenomena have been reported in cases of extended pipeline distance and elevation change. Separating the liquid and gas very near the subsea wellheads is expected to significantly reduce pumping problems, required pumping horsepower, and many problems associated with hydrate production.
- 2001 SPE Applied Technology Workshop. 2001. Subsea Processing, Houston, 6–7 May.
Noteworthy papers in OnePetro
R. Lopez 2005. Field Trials of an All-Electric Subsea Completion System, Offshore Technology Conference, 2 May-5 May. 17392-MS. http://dx.doi.org/10.4043/17392-MS
B.F. Baugh 1989. The Economic and Design Impact of Standardized ROV and Diver Interfaces on Subsea Completion Systems, Offshore Technology Conference, 1-4 May. 6044-MS. http://dx.doi.org/10.4043/6044-MS
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