We made a total of four milling runs and eight fishing attempts to try to remove the failed drill pipe and BHA from the hole. Each deployment is documented in the body of this report. We used both 8-7/8" and 9-1/2" overshots in our fishing attempts. We used a 6-7/8" basket grapple and mill control to engage the upset connection on the 5" drill pipe tool joint (7" OD) on the first attempt and ultimately recovered 497 m of 5" drill pipe. For all subsequent fishing operations, we used a 5" basket grapple and mill control to try to engage the tube body of the failed 5" drill pipe. These attempts were all unsuccessful. We considered using a taper tap fishing tool to attempt engagement of the inside diameter of the fish, but this was ruled out for several reasons. First, the failed end of the tube was crushed where the pipe buckled upon impact with the seafloor. Unless the milling attempts were successful we would not have been able to engage the fish internally. Second, the taper tap had no way to circulate to the bottom of the fish, which was likely firmly stuck in the hole at that point. If the fish was engaged with the tap, and was indeed stuck in the hole, we had no jars in the string and no way to disengage the tap. To prevent sidetracking the fish, we fabricated a wall hook from a 9-1/2" extension sub and an 8-7/8" extension sub. This would not have been a problem if the 5" basket grapples and mill controls for the 9-1/2" overshot had been available, but they were only available for the 8-7/8" size overshot. In addition, we had some incompatibility associated with the 8-7/8" overshot hardware that limited our tool make-up. We had one top sub with a 6-5/8" box and another with an old Hycalog box thread dating back to the Glomar Challenger days. We really did not want to run the Hycalog thread because the fish weight was nearly 100K w/o overpull, and the thread possibly could see some bending loads for which it was not designed. The bottom threads on the top subs were different, so we ended up with only one overshot bowl that would screw onto the stronger top sub and two that would only fit the weaker top sub. In addition, the extension subs we had would not make up to the stronger top sub. After the first run the Hycalog box thread was damaged (egged and shoulder damage) and was very hard to make up on later runs. It was the only option, however, when we wanted to run an extension sub to try to swallow the fish deeper.

We returned all of the 8-7/8" overshot parts to shore. We felt that this was the most practical way to solve the thread incompatibility problems and get things back in shape for future potential fishing jobs.

The following 9-1/2" overshot parts were used on Leg 176 and were either damaged or lost: One each OF2020 lip guides, one each OF0132 mill control, one each OF0035 basket grapple, one each OF0140 inner seal, one each OF0630 9-1/2" Extension Sub, and one each OF2023 flat bottom guide.

The following list of overshot parts would help out future fishing operations:

1. 2 each — 9-1/2" OD lip guides for the 8-7/8" overshot
2. 2 each — mill controls for the 9-1/2" overshot assembly
3. 2 each — basket grapples for the 9-1/2" overshot assembly
4. 1 each — 9-m long 8-7/8" extension sub
This would allow fishing the next tool joint instead of trying to fish a damaged tube. It would have to have heavy duty thread protectors on it because it would be stored in the riser hold. Also a short crossover would be good to allow running a 9-1/2" overshot with the long extension sub.
5.Beef up our inventory of lip guides for both the 8-7/8" and 9-1/2" overshots.
6.Do away with the Hycalog top subs altogether. This is a really poor connection for fishing operations. It also requires running a long bit sub as a crossover, which is also weak because it is bored out for the float and bearing. We also have the same connection for one of the 9-1/2" overshot assemblies that needs to be replaced.
7. Sort out the thread compatibility problems with the 8-7/8" overshot top sub to bowl.
8.Provide a junk mill with an extreme concave face to center a drill pipe tube better and not allow it to fall so easily off the fish you are attempting to dress.

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