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Woods Hole Group Current Profiling Systems in the Gulf of Mexico

Drilling rigs operating in the deep waters of the US Gulf of Mexico (GOM) are required to make current profile measurements through the upper 1000 meters of the water column and to provide those profiles in near-real-time to a public database hosted by the National Data Buoy Center (NDBC). The requirement applies to all rigs operating in water depths exceeding 400 meters. The measurements are used to support rig operations, inform future production platform and riser designs, and improve understanding of physical oceanographic processes in the GOM.

Seadrill West Auriga drillship - Length overall ˜250m

To satisfy these requirements, Woods Hole Group has installed and is operating current profiling systems on multiple drill ships, including four modernized systems for BP America. Installation of a fifth system is expected to be completed by the end of October, 2014, and we anticipate beginning construction of a sixth system this winter. This growing list of Woods Hole Group installations now exceeds 10% of the industry fleet of mobile drilling units (MODUs) in the GOM. Just prior to publication, Woods Hole Group personnel were on-board the Ensco DS3, another drill ship, completing hydraulic and computer connections prior to system testing and commissioning.

Woods Hole Group Launch and Recovery System on the Ensco DS4 in the GOM

Woods Hole Group has a 15+ year history of rig system work, including in Indonesia, Australia, West Africa, Trinidad, and offshore Brasil. The first of the more modern current profiling systems was designed by the Oceanography and Measurement Systems (OMS) team of Woods Hole Group in 2009. It was installed on the Deep Ocean Clarion (since renamed the DS4) in 2010, which subsequently spent several years operating offshore Brasil before returning to the GOM in 2014. The advantages were well received by the industry. During factory acceptance testing in Houston the first system was described by the customer as “a game changer”. That did not stop Woods Hole Group from improving the design for the systems that followed:

  1. The Woods Hole Group design takes advantage of an OO38 Underwater Electronics Assembly (UWEA), which can be submerged with the transducer. Using these cables, winches with slip-rings, and an articulated A-frame, fewer personnel at much reduced risk of injury can more quickly launch and recover the instruments with little risk of equipment damage.
  2. To overcome space limitations aboard rigs that constrain placement of the system components to locations high above the water, Woods Hole Group designed a gantry deployment system welded to a cantilevered platform. An A-frame lowers a sled with the 2 current meters (ADCPs) below the dynamic positioning thrusters extending below the keel. All of this increases measurement quality, and can be accomplished by a single operator and a spotter/safety observer in minutes and with minimized risk of injury.
  3. The winches and A-frame are hydraulically driven from an operator control stand positioned to afford a clear view of the deck area and the water below.
  4. The electronic components of the system, principally the sensors, data connections, and measurement displays, are automatically controlled by Woods Hole Group’s Integrated Remote Monitoring System (IRMS) software and do not require action by the operator. The system will independently detect when it is in the water and will begin making measurements.
  5. There are two current meters that profile current speed and direction from the water surface to a depth of 1000 meters. The instruments are powered, controlled, and deliver data through the electro-mechanical cables, from which the 1500 lbs sled and instrument assembly is suspended.
  6. The ADCP PC, running Woods Hole Group’s IRMS and a small suite of commercial software packages, controls the system, provides local and remote operator interfaces (the latter through a secure internet connection), generates data displays available throughout the rig to support real-time operations, and automatically transfers data to NDBC and Woods Hole Group.
  7. Currently under development is a Woods Hole Group GOM Rigs website, which will provide the rigs and users on-shore with additional real-time data displays, archival data, and downloadable data tables and images designed to meet the operational needs of rig crews.
Woods Hole Group Integrated Remote Monitoring System operator display

Woods Hole Group also designed and installed the mechanical components of launch and recovery systems (LARS) on multiple other drill ships. For instance, the system on the Pacific Drilling Pacific Santa Ana for Chevron features rigid vertical rails along which a carriage carries the ADCP. Carriage position is controlled with a winch and the ADCP can be positioned close to the deck for maintenance. When deployed to the bottom of the rails, the ADCP is held rigidly and cannot rotate or swing. This stable platform provides the highest possible data quality and minimizes the risk of equipment damage in rough weather or high currents.

Electronics enclosure control and monitoring interface

After installations are completed and systems become operational, Woods Hole Group personnel regularly visit each rig, performing standard and preventive maintenance, ensuring the systems continue to operate smoothly, and providing operational training to rig crews. GOM rig systems have been a successful undertaking for Woods Hole Group. Our designs and services are well regarded and, with a number of new-build rigs scheduled to begin GOM operations in the next few years, there is promise of a growing market.

Submitted by:

Todd Morrison
Senior Ocean Engineer

Contact Information:
Woods Hole Group
81 Technology Park Drive
East Falmouth, MA 02536

Bruce Magnell
Sr. Scientist/
Oceanographer

David Szabo
Manager/
Sr. Oceanographer

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