SEDCO 709--FIRST DYNAMICALLY STATIONED SEMI-SUBMERSIBLE
SEDCO 709, the world's first dynamically positioned semi-submersible commenced drilling before the summer of 1977. Part I of this article describes the dynamic stationing and related control systems involved in the operation of the rig. Preliminary design and testing, a basic control scheme for azimuthing thrusters known as "pinwheel moment" and the dynamic-stationing environmental limitations are described. The position reference system and the computerized power management system are also described. The former involves a Honeywell RS7 acoustic position reference system of which two are used, each computing the vessel position based on separate hydrophone arrays and subsea beacons. The latter system monitors and records more than 1,000 data points around the vessel as well as making stability and load calculations, performs data reduction and runs drilling programs, apart from controlling the power plant. Part II of the article describes the Data Management System which helps reduce maintenance costs. Part III describes the controls which are specially designed for deepwater guidelines re-entry and the blowout preventer (BOP) system. Innovations in marine riser design and the multiplex telemetry for stack control are described. SEDCO 709 is also provided with emergency controls in the event of a drive-off and a third back-up consisting of an acoustic BOP control system. The rig uses second generation re-entry techniques that focus on a combination sonar and television re-entry tool.
- The document also includes Volume 12, January, 1977.
Gulf Publishing CompanyBox 2608
Houston, TX USA 77001
- Publication Date: 1976-12
- Pagination: 9 p.
- Ocean Industry
- Volume: 11
- Publisher: Gulf Publishing Company
- TRT Terms: Data processing; Drilling; Drilling ships; Dynamic positioning; Offshore drilling platforms; Risers (Geology); Semisubmersibles; Thrusters; Underwater construction
- Uncontrolled Terms: Data management
- Old TRIS Terms: Deep water drilling; Drill ships; Marine risers; Positioning control systems
- Subject Areas: Marine Transportation; Operations and Traffic Management;
- Accession Number: 00174223
- Record Type: Publication
- Source Agency: British Ship Research Association
- Files: TRIS
- Created Date: May 31 1978 12:00AM