Technology and Engineering Development Committee (TEDCOM)

October 1996

TEDCOM recommendations to PCOM

TEDCOM Recommendation 96-2-1: Active Heave Compensation

TEDCOM will advise PCOM, by the December 1996 meeting regarding Active Heave Compensation (AHC) which could be fitted to the JOIDES Resolution to improve coring.

TEDCOM Recommendation 96-2-2: HDS

The Hammer Drill Project should be closely monitored and be slowed down if good information and favorable results for a JOIDES Resolution operation are not forthcoming from SDS, rather than trying to attain a product for an engineering test leg in 1997.
Action: Two TEDCOM panel members will monitor the progress of this project.

December 1996

Recommendations from DCS Subcommittee meeting-DCS Recommendation

• At the last TEDCOM meeting, ODPTAMU proposed deferral of currently planned work on the DCS secondary compensator system and purchase of a commercially available system to provide active compensation to the JOIDES Resolution primary drill string compensator, which is now passive. TEDCOM requested its DCS subcommittee to review this proposal in depth and make its recommendation to PCOM. The DCS subcommittee developed these recommendations:
• DCS Phase 3B and succeeding steps should be put on hold.
• ODP should proceed with simulations including active primary compensation as applied to the JOIDES Resolution.
• ODP should proceed with obtaining detailed proposals and competitive bids from Retsco, et. al. for the system.
• Provisional with available funding and satisfactory simulation results, a high quality active heave compensation system should be procured and installed on the JOIDES Resolution.
• A continuing level of effort by ODP on DCS system and alternatives should be retained.

The JOIDES Resolution present passive drill string compensator absorbs 75%-80% of vessel heave with 2500m of API drill string riser attached to the sea floor. Addition of AHC is expected (guaranteed by prime candidate vendor) to increase this to about 90%, and actual performance may be in range of 95%. With this, there is some possibility that much of DCS coring could be accomplished without need of a secondary heave compensator and would provide the large advantage of moving the DCS operator down to the rig floor level. Even if secondary compensator for DCS is eventually required, it could be accomplished more readily. Additional advantages of a more everyday nature for AHC include the following:

1. Core recovery is expected to be improved in all formations, especially under high heave conditions.
2. Capability for landing of equipment on the sea floor, e.g., guide bases, CORKs, reentries, bare rock spudin should be improved.
3. Capability for improved operation of a wider range of coring and evaluation tools, e.g., logging is possible.

HDS recommendation

• ODPTAMU proposes to carry out a three stage testing program of the SDS 12 ¼" diameter water percussion drill.
  Bench testing in Australia (motor only) January 1997.
• Downhole drilling tests in Norway (motor and bit only) January 1997.
• Sea trials on the Resolution (hammer, bits, drillin casing system) July 1997.
• Success in these three steps would be followed by development of larger and smaller hammers for routine applications.

Subcommittee recommendations to PCOM

• PCOMs full support of this planned test sequence, assuming timeliness and tool success at each prior stage.
• More refined analysis of drill string/casing behavior during set down for barerock spud-in.
• Moderate advance expenditures to maintain timeliness of succeeding steps.

[ 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 ]