Years ago — well, it was the ’80s — we received a call from a West Coast customer who was having thread problems on his new Driltech rig. After a couple of months, some of his threads were becoming damaged to the point that they would no longer shoulder, and some were really difficult to break. I made arrangements to meet the local Driltech rep at the Sacramento airport.
Meanwhile, all the possibilities were running through my head. Was this a case where we made a bunch of bad threads? Or, maybe we made one bad thread whose damage was migrating through the entire drill string? Maybe the threads were good, but we damaged them during the welding, cleaning and painting process. Maybe the operator damaged the threads. Maybe they were using generic grease instead of a good grade of tool joint compound. What if I cannot find the cause?
It was enough to keep anyone awake at night.
I packed up a thread gage and dial caliper, and flew west. Bob Freeman with Driltech picked me up at the airport and we headed east. We rode in style, as the only car he could rent was a Cadillac.
Around here in south central Pennsylvania, a “mountain” might be 2,300 feet in elevation. As we drove east on I-80, I noted the elevation signs: 3,000 feet, 4,000 feet and then 5,000 feet. Wow. I hadn’t been so high and still on the ground since my college days.
We exited the interstate and headed down a narrow road. We soon pulled off into a driveway that led to a cabin for a campground. The rig was a couple of hundred yards away on a new site, but there was no road. Freeman and I proceeded to drive through the forest in the Cadillac until we found the rig. They were drilling a new well.
Once on site, I looked over all the pin threads I could see. They all showed some thread damage — a lot of rough spots. Some had severe damage from galling. Many were on a spectrum between those two conditions. I saw no evidence of stabbing. I checked out their tool joint compound, and it was good and kept clean.
Freeman and I stood back and watched the drilling operation for about an hour or so. We did not see anything outside of good drilling operations. But, while they added a new drill pipe, I took a closer look. As the operator guided the new pipe onto the one in the table, he carefully rotated up to the shouldering point. When they lacked a 16th-of-an-inch from shouldering, the holding wrench went to one side. You could actually see the strain as more torque was needed to complete the shouldering. This was a sure sign of a problem.
Was it because of existing thread damage, or was something else not quite right? Typically, when adding drill pipe, the operator takes a new joint from the carousel and then lowers it to the connection on the drill rod held in the table. I noted that it took more than a nudge for the operator to push the new pipe into alignment with the one in the table. The rig was level, but something was not right.
I then noticed that the split table was open and an inch or two short of being where it should be. I asked the driller if that is the way it always had been. No, he answered. They had sent out their deck bushing for repair and were using a bushing from another rig. It was bigger, so they had to open the table and then squeeze it to keep it in place.
I kind of grimaced and gave the driller a raised-eyebrow look. He then said: “What was I thinking?”
The substitute bushing’s hole was not properly aligned with the drive spindle. Every make up and break out put undue pressure on one side of the connections. I believe that this was causing undue wear, which led to the problems. When you need to open your table to run large diameter pipe or casing, the head is no longer aligned with the center of this larger table opening. In theory, you would need to shim out the head to bring it into alignment.
The customer put a new top sub on the rig. Most of the drill pipe was repaired by a local shop, but they also purchased some new pipe. No further thread damage was noted and all drilled happily ever after … as far as I know.
Freeman and I headed back to Sacramento and he dropped me off at the airport. It was a good trip. This is one of my better experiences troubleshooting drill pipe problems. I saw new scenery, met a new friend, discovered a new cause of thread problems and met one embarrassed driller. Finding a substitute bushing was a good idea that was not thought through — kind of like when I put in a dog door so I would not have to let the dog in and out. It became a raccoon door and an opossum door and then a stray cat door. I guess I should have thought that through a little more.
Sometimes a solution fixes one problem, but introduces new ones. You might install a dog door, only to find a raccoon sitting on your microwave one morning. Or, you might end up spending money to fix and replace drill pipe because of a decision about a deck bushing. These are all problems created by solutions to other problems. Changes can reverberate through your operations. Take some time and think through your solutions.
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