Chevron Corp., ConocoPhillips, ExxonMobil Corp., and Royal Dutch Shell PLC announced in July plans to engineer, construct, and deploy equipment designed to improve capabilities for containing a potential future underwater blowout in the Gulf of Mexico (OGJ Online, July 21, 2010).
The companies said the advantages of the system over the current response equipment include being preengineered, constructed, tested, and ready for rapid deployment in the deepwater Gulf of Mexico. The system's objective is to contain the oil with no flow to the sea in water depths up to 10,000 ft and in weather conditions and flow rates that exceed those realized during the Macondo well blowout.
The companies plan to maintain the system in readiness so that it can be mobilized within days and fully operational within weeks.
Implementation
The companies said that they initially will invest about $1 billion for constructing the new subsea and modular process equipment and they have designated ExxonMobil to lead the engineering, procurement, and construction of the system's components.
Their plan is to secure existing equipment and make it available within 6 months and complete the new system within 18 months.
The companies will form a new nonprofit organization, the Marine Well Containment Co., to operate and maintain the system. They are encouraging other Gulf of Mexico operators to participate in the new organization.
System components
Components of the system include a containment assembly, a capture caisson, a riser, hydraulic-electric controls, chemical injection, a subsea manifold, quick riser and umbilical disconnects, subsea dispersant injection, and surface components (see figure).
The companies said that the newly designed and fabricated subsea containment assembly will create a permanent connection and seal to prevent oil from escaping into the water. The assembly will have a suite of adapters and connectors to interact with various interface points such as the wellhead, blowout preventer stack, lower marine riser package, and casing strings, including any well design and equipment used by various operators in the Gulf of Mexico. Also the assembly will have a design that prevents hydrate formation and blockage.
Another part of the system is a capture caisson assembly for enclosing, if required, a damaged connector or leak outside the well casing. Once installed, the containment and caisson assemblies will create a seal with the seabed to prevent seawater from entering the system.
The captured oil will flow through a flexible pipe to a riser assembly with a seabed foundation. The riser is a vertical pipe with buoyancy tanks and a flexible pipe configured to connect to the capture vessels.
The subsea manifold with an umbilical will have hydraulic-electric controls and chemical injection capabilities such as for injecting hydrate inhibitors. The manifold also will distribute oil to multiple riser assemblies if more than one capture vessel is needed.
The riser assemblies and umbilicals will have quick disconnects for being released from the capture vessels in case of hurricanes so that all subsea equipment will stay in place. The system will allow the vessels to reconnect and be operational within days after the weather event.
The system also will have a component for injecting dispersant into the subsea containment assembly, if required.
The capture vessels for the system will have the capability to process, store, and offload the oil to shuttle tankers.
The plan includes construction of modular process equipment for installation on the capture vessels. The modules will connect to the riser assembly, separate oil from gas, flare the gas, and safely store and offload oil to shuttle tankers that will be US-flagged and Jones Act compliant.
Correction In "Design optimizes sour-crude production facility" by S.G. Alborzi and J. Hargreaves (OGJ, Aug. 2, 2010, p. 76), the title of Fig. 1 should have read "Multistage separation without rvp control." |
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