The vast majority of time an operator runs a cable-tool rig, they either make a hole or drive casing into the ground. On occasion though, the operator needs to remove or pull casing from the ground. Three instances that come to mind include:
- Setting a telescoping screen,
- Removing a bent lower section of casing to replace it,
- And, heaven forbid, drilling a dry hole.
Operators have several methods for successfully pulling or removing casing. Here, I start with easiest and go to most difficult.
Using a Casing Reel
In situations where casing remains close to the surface, say 50 or 60 feet, operators can simply use a casing reel if the rig has one. (Some cable-tool rigs have only drilling and sand reels, so this method won’t work with them.) The driller simply grabs the casing with an elevator, which I wrote about last time, a chain or even a sling made of steel cable. This method depends on the formations drilled through. If these formations consist of clay, pulling by casing reel works. If the casing encounters a lot of sand, which grips the casing tightly, this may not be possible.
Small cable-tool rigs used for water wells usually have a casing reel capacity of from 5,000 to 14,000 pounds. Some large rigs may have a capacity in excess of 100,000 pounds, but these rigs rarely get used on 4-, 5- or 6-inch water wells.
When pulling casing by this method, pay attention to mast capacity. I know of a small cable-tool rig quite popular in the Midwest for 4-, 5- and 6-inch wells that had a bad design flaw. The upper section of the telescoping mast could easily bend. Other than that flaw, I generally still view these rigs built by a well-known manufacturer as well engineered for a long life. I ran a couple myself. But I heard of many drillers who would bend the mast, sometimes severely.
Bumping the Casing
If conditions not favorable to using a casing reel, we need to use kinetic energy. In this method, we use the energy in the tool string to pound upward, or “bump,” the casing. The simplest way to do this involves a pipe-pulling plug — sometimes called a knocker head. This device consists of a thick steel plug with a slot in it. The operator lowers the tools into the hole and slides the pulling head over the drill cable. The pulling head then screws into the top coupling of the casing. The operator then starts the spudding action and raises the tools to a point where they hit the pulling head at the top of the stroke. Some rigs have an adjustment in the character of the stroke so that, when pulling pipe, the tools have a fast upstroke and a slow downstroke — just the opposite of the drilling motion.
This pulling head gives you a cheap and easy way to bump pipe out of the ground, but has more effectiveness in not-so-severe pulls. Note also that pipe-pulling plugs were limited to casing from 3-inch through about 10- or 12-inch — which covered most any water well drilling in Michigan.
Using a pulling head has one major downside. It can batter the neck of the rope socket, making it nearly impossible to fish for this part of the tool string if it sticks or the cable breaks at the socket. However, some smart designer came up with a heavy sleeve with a slot in it that also fit over the drilling line and rests on the shoulder of the socket. This eliminates battering the neck of the socket. We used this type of protector on all our rigs and found it effective at keeping the fishing neck of the socket in good shape.
Using Pipe-Pulling Jars
The next tool in the toolbox the driller has to pull casing is pipe-pulling jars. Jars consists of a drill stem 4- or 5-feet long with tapered male and female joints. Near the lower joint but above the square, you find an enlarged section that gives it a good-sized shoulder. Operators can use that shoulder to bump against a head, which is something like an extra heavy drive head screwed into the top coupling. You install these jars between the drill stem and the socket and they work much like the pulling head mentioned earlier (but with some extra weight).
When using pipe-pulling jars, you can also add drive clamps to the upper square. If you do and end up breaking the drill line while bumping casing, the drill string falls harmlessly on the drive clamps. If the drill line breaks while using a pulling head, the whole tool string goes to the bottom of the hole almost instantly. Anything in the hole, like a well screen and perhaps a weight to hold it down when using a neoprene seal on the screen, would be destroyed.
I had this happen one time in my career and it sure made a huge impression on me. Without too much difficulty, I retrieved the drill string, the screen weight and the remains of the screen. After restringing the tools to the drill line, I successfully set the screen a second time only to get an unsuccessful well. I had to pull the screen again and go deeper. This happened over 50 years ago and I can replay the scene in my mind as I write this. I had a pipe pulling jars for my rigs, and found it more effective than a pulling head but not much more. It also took a longer time to rig up, as you had to make and break joints to install it in the tool string. These pipe-pulling jars are available from one manufacturer from 4-inch casing up to and including 16-inch.
I plan to discuss other methods to pull casing with a cable tool rig in my next column. In the meantime, every driller I know is extremely busy — no matter what type of rig he runs. Some of them even have work scheduled out through next spring, which sounds too busy to me.
Locally, we have had some warm weather and some cool and seasonal rains seem to have tapered off, although lawns still look green and field crops look great. Until next time, work hard, work safe and enjoy life on occasion.
For more John Schmitt columns, visit www.thedriller.com/schmitt.
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