World Oilfield Forum
Feb. 8th, 2013
In the course of my fishing duties, up here in the Bakken, I have run into a problem that is enough to make a fisherman pull out his already thinning hair.
I often get a simple pick-up job to retrieve a tubing anchor and 2 or 3 joints of tubing. Easy job. Except, the fish doesn't weigh much and the rig has tied back the dead line to the drum. This forces the rig to use 'pad mounted' weight indicators.
The way this joke works is, there are 2 load sensors under the derrick legs. They pretend to weigh the derrick, the block, the floor, the tongs, and however many hands happen to be on the floor at any given time.
In good weather, which doesn't happen too often around here, the resolution is around two to five thousand pounds. It gets worse below zero. I might as well be looking at a weather vane as a weight indicator.
This makes it very difficult to tell whether I have picked up the fish.
Of course the company man is standing right there, asking whether I have caught the fish or not. Since it is impossible to tell, I just tell them to trip out, and we'll see... If I've got it, fine. If I missed the catch, a prayer meeting with the company man is in my future. And the costs go up...
I spent a fair amount of time thinking about this. I realized that I needed to know the weight of the string, rather than all that other equipment that has nothing to do with the weight of the fish.
My solution was to build a hollow, wireless load cell. I drop a short pup joint through it and latch the elevators under it. We screw it into the string and pick up. It reads on a screen in my hand, within 100lbs. Since most everybody uses 2 7/8 EUE tubing up here, I built the first model to fit this tubing. With other tubing sizes, I use a cross-over. I can confirm the catch of very light fish, and save the rig crew another trip.
After discussing the engineering with my partner (a scary-smart guy) and the company that built the unit for us, we got the first unit in hand. I took it on my own fishing jobs, and offered it to the customers for free, so I could test it. It went very well, with some minor adjustments, and now it is on the books. I don't sell them, I rent them, just like jars. We formed a company to produce and market the tool.
We have discovered other uses, also. When setting tubing anchors, it is important to pull the right stretch weight to prevent rod-box wear, or tubing buckling. It also prevent premature shear-out of the anchor, something a weather vane weight indicator won't do.
When milling, it is extremely important to maintain an accurate WOB. This is easily done. When I get to bottom, and tag the fish, I pick up and slack off to establish my drag weights, then toggle the hand-held unit to read WOB. I put it in front of the driller and tell him how much weight I need on my mill. Whether it is 200, 500, or 1500lbs he can keep my mills performing as designed.
It is also very useful for jarring, especially near the upper limits of string tensile strength. I'm not weighing the block, the floor or anything else. I know what I can pull on a string, and I have a very precise way of knowing.
We're hoping this tool will take off soon. If you need it, give me a call.
Wayne (912) 223-6521