Akpo: A Giant Nigerian Deep Offshore Development
- Karen Bybee (JPT Assistant Technology Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- October 2010
- Document Type
- Journal Paper
- 39 - 41
- 2010. Offshore Technology Conference
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- 126 since 2007
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This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 20989, "AKPO: Early Completion of a Giant Nigerian Deep Offshore Development," by Francois Rafin, SPE, and Allain Laîne, Total S.A., originally prepared for the 2010 Offshore Technology Conference, Houston, 3-6 May. The paper has not been peer reviewed.
Akpo field was discovered in January 2000 and production started ahead of schedule in March 2009 in Block OML 130, 200 km offshore Nigeria in 1400-m water depth. The Akpo project faced the challenges of combining gigantic scale, new technological frontiers, world-scale industrial execution, scarcity of resources in booming years for the offshore industry, and setting new records of local content in an unstable Niger delta.
A unique hybrid gas-injection/gas-export development scheme was chosen to maximize hydrocarbon recovery with massive pressure maintenance and the extensive use of intelligent and selective completions and subsea multiphase-flow measurements.
The wellhead shut-in pressure of 430 bar and temperature of 116°C represented new frontiers for the deepwater industry.
To deliver a 72-slot, 44-well, 10-manifold, 14-steel-catenary-riser (SCR) subsea development in West Africa, the project strategy was to use generic and qualified systems and equipment. The Akpo field characteristics required several technological innovations and the development of existing technology such as:
- All-electric floating production, storage, and offloading (FPSO) vessel with a centralized control room on each topside module
- Inconel-clad SCRs with high-pressure/high-temperature flex joints
- One fully integrated control and safety system from wellbore to FPSO topside provided by a single contractor
- An internally flow coated 155-km-long gas-export line that increases the flow capacity by 20%, enabling (because of a reduced diameter) the use of seamless pipe
- Crushable foam and bursting disk to control the well annulus-pressure buildup, because no casing steel is available to withstand the stress at Akpo pressure and temperature conditions
- First 10¾-in. frac-pack runs in a single trip
- First use of 7-in. expandable screens for a subsea application
- Intelligent completions with downhole monitoring and control from the FPSO control room
- Automatic ultrasonic testing system for Akpo subsea pipelines, capable of detecting defects smaller than minimum acceptable
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