ODP/TAMU carried out an in-house technical audit of the present derrick mounted DCS and also commissioned an independent safety assessment to comment upon the use of the DCS. Both reports gave it a fundamental clean bill of health from a safety and technical viewpoint, with associated recommendations for improvements.
In continuation of the TEDCOM recommended phasing of DCS work, the JOIDES Resolution Top Drive and Compensation System has been instrumented for collection of data during the range of coring and drilling operations. Data are being collected at present. Initial teething problems have been ironed out and Leg 170 is attempting full data gathering. This data collection is to be used to verify the controller system and simulation studies already completed, and proceed the DCS to a land test using the new controller. Some of the data collected may be unreliable due to the specification of the sensor. This is being investigated at present.
The primary heave compensator seals have been reviewed and options to change are now available. Measurements will be made on the condition of the cylinders during the June 1997 Halifax port call (Leg 174A) and two replacement options, plus re-packing with original type materials, will be the choices available. If at all possible the sensors presently fitted will remain in order that the performance of the compensator, with new seals, can be evaluated. The most favored seals can only be used if the cylinders are in good condition and this cannot be determined until inspection which will take place at the same time as replacement. An operation schedule has been developed.
The ultimate aim of the DCS is to operate it at the rig floor (DCS Phase 3). It has been proposed that work on the DCS in its present form stops, and consideration be given to using the immediate savings to purchase an Active Heave Compensator (AHC) system to act as the primary heave compensator. AHC has already been identified by TEDCOM as being useful to assist (together with low friction seals) in bringing the residual heave that the secondary compensator has to deal with, down to acceptable levels.
An AHC system will improve all coring activities on the JOIDES Resolution, and may allow the secondary active heave compensator on the current DCS design to be eliminated.
(See Technology and Engineering Development Committee (TEDCOM).)
[ Contents of the Semiannual Report, No. 2, June-November 1996 |
| Program Updates | New Initiatives | Project Summaries | Laboratory Working Groups |
| Panel Recommendations | Appendixes |
| Semiannual Report, No. 1, December-May 1996 ]