Garden Banks 388 ROV Interface Systems
Authors: Granhaug Otto , Brewster David 
Published: October 2008

ROV systems integration has become an important part of the planning and implementation of deep water field development. This paper provides an overview of the GB 388 subsea development project and describes the ROV interface systems in use on the various subsea production components. The paper continues with an account of the purpose-built ROV system developed for the project. Finally, the paper describes in some detail the specialized ROVtooling and intervention systems that have been developed to assist in the installation, operation and maintenance of the subsea production equipment.

The subsea intervention solutions developed for the GB 388 development project have direct application to all deep water field development projects. ROV interface systems are anintegral part of current and future subsea completion technology.

PROJECT OVERVIEW

Enserch Exploration, Inc. (Enserch) is developing oil/gas reserves discovered in Garden Banks Block 388 (GB 388) in the U.S. Gulf of Mexico. The field uses subsea drilled and completed wells tied back to a floating production facility located directly above the subsea template/wells. The field is located in approximately 2,100 Feet of Sea Water (FSW).

The design capacity of the Floating Production Facility (FPF) is 40,000 BOPD and 120 MCFPD. The subsea wells are tied back to the FPF through a free-standing production riser with integral production and control lines. Oil and gas are separated and the gas stream is dehydrated onboard thePF. The processed oil and gas is piped through two 12' lines running from the subsea template to the Shallow WaterFacility (SWF) located in Eugene Island Block 315, where final processing takes place.

The subsea wells are drilled through a 24 slot subsea template by use of the drilling facilities on the floating production vessel. Four appraisal wells have already been drilled at the template location. Three of the four will be completed and tied-in to the main template structure. The template can accommodate 24 wells and up to 14 of those can be satellite wells.

The extensive use of subsea production technology combined with the 2,100 foot water depth, cause heavy reliance on diverless intervention through the use of Remotely Operated Vehicles (ROV). For the GB 388 subsea development, Enserch elected to use a new purpose built ROV system provided by the ROV contractor on a long term lease basis. The new ROV system incorporates state of the art systems design, combined with sufficient power capabilities and versatility to handle all the specific workrequirements of the project. The FPF was modified to provide an ROV handling system including a dedicated moonpool and cursor system for enhanced launch and recovery.

ROV expertise was brought in early in the development stage to provide input in areas of design, installation and operation of the subsea equipment with respect to ROV intervention. ROV representatives were involved in equipment design review and offered valuable input on the practicality of the ROV tooling and equipment interfacing. The ROV interface solutions and tooling arrived at during the engineering phase were later thoroughly tested.