Dear readers, I’m writing this in very early January 2013 and although you will read this a little later, I hope you had a prosperous and safe holiday. In southern Michigan we have a nice covering of snow, perhaps 4-inches deep, and the weather has not been too bad-although it did get down to single digits on the thermometer on the evening of New Year’s Day.
Those of you who live in cold climates are no doubt familiar with ice fishing where folks go out on the frozen lakes, cut holes in the ice and drop in a line. What you really want for this activity is a fishing shanty, which is some sort of a building or shelter to keep the wind off and keep one warm. You can buy models that are mounted on sleds and can be easily collapsed and taken off the ice at the end of the day, and those are pretty cozy. Some folks just build something out of cheap wood and leave it in place. Some are quite elaborate, with heaters, padded chairs and TVs. In the spring every year, someone will forget to get his shanty as the ice melts and it will sink, at least partially.
To be safe out on the ice it needs to be about 4-inches thick. We have not had really cold weather and, with snow as an insulator, most of our lakes in southern Michigan have about 2 inches of ice-an unsafe amount to even walk on. Sadly on the news the other evening we learned of a fellow who went through and drowned-his body recovered by the local safety folks-a sad, sad event. But this sad event reminded me that I had planned some articles about cable tool fishing. Actually, in late summer, I got a short letter from a driller with some questions about this type of problem, and he mentioned that he had never seen an article on this subject.
Before I go any farther, please understand that I am only relating personal experiences and discussions that I have had with other drillers. Neither I nor National Driller make any claims or guarantees about fishing tools, methods or procedures. As I said, this is just one driller to another in a friendly manner.
Perhaps the most common fishing job of all is not really fishing out tools but loosening them up. This we would call loosening a stuck tool string. This most commonly occurs when a driller is not, repeat not, running drilling jars on his tool string. As the drill bit is upset at its bottom end to be brought to full gauge or diameter it forms a tapered shoulder at that point. If we drill in a formation that has small stones or pebbles, once in a great, great while a stone will wedge the drill bit against the casing or actually the drive shoe. The tool string will not fall and no matter how hard one pulls on the drill line, the string will not move.
The solution to this problem is a quite simple one and that is to run a tool called a jar bumper. This is a device made of steel in a U shape that slides down the drill line when attached to the sand line. Upon encountering the stuck tool string, the jar bumper is raised several feet to start with and allowed to free fall to hit the top of the tool string. Most drilling tool catalogs recommend that the drill line be kept tight and when the jar bumper hits the tools it will stretch the drill line, move the tool string downward a little bit and our annoying pebble or stone will fall away. If the first blow isn’t successful, repeated blows from the bumper are necessary, letting this tool fall a little farther each time.
In my own experience, I had better luck by allowing the drill line to be slightly slack. The jar bumper would then drive the drill string down a little bit causing the desired effect and allowing our stone or pebble to fall away. When the tools are loosened the bumper is removed and the driller can go back to drilling. The bromide or quick and dirty rule that I used was, if the tools got stuck twice within a short time the ground was trying to tell me something and it was time to put the drilling jars on.
Now this brings up a matter than can cause considerable discussion, and that is whether or not to use drilling jars regularly. As I have mentioned in earlier articles, most drillers are highly opinioned on many topics including, “what’s the best pickup, the best drill rig and the best tasting beer.” I know some drillers who hardly ever ran drilling jars. I was one of them. I know other drillers, good ones in fact, who always ran drilling jars even when drilling in the same formations that the “no jars” guys did.
I recall a manufacturer of cable tool rigs, who made many thousands of them, recommending that drilling jars never be run when casing was being driven. I know some of you will strongly disagree and others will agree. Most likely, whether or not to run drilling jars has a lot to do with the formation being drilled. Certainly in bedrock formations, I believe that jars should always be run, but I do know of some guys who drilled shale formations without jars.
Jar bumpers are made in a couple of styles, one long and skinny, the other short, fat and heavier. In my opinion a jar bumper is absolutely essential to the equipment roster of every cable tool drilling rig.
Another use of the jar bumper is to free stuck jars. It would certainly work for that, although in my years of drilling I don’t recall ever having stuck jars. If, for whatever reason, the jar bumper will not loosen the tool string, the driller is into a much more complicated situation and is then actually fishing for tools rather than loosening them. I will address fishing for a tightly stuck string in my next article and also how to proceed if the drilling cable breaks.
As I said at the beginning, we have had a decent winter here in Michigan and hope it has been that way wherever you are. Continue to work both profitable and safely. ND