Drilling Consolidated Material

Drilling Consolidated Material

Once the casing is in place, you then attach your tricone bit or hammer, whichever you are going to use, with the proper size bit onto your drill rods and put them back in the hole to the bottom. However, as you approach the bottom you should apply air to the hammer or drill bit as it is quite common for the pipe to have a plug of overburden in it when you go back into the hole after setting the pipe. By rotating and blowing as you re-enter the hole, you blow it out the top and do not plug up your bit. This would readily clear the hole, allowing your bit to sit down on the new rock formation at the bottom of the hole.

If at this point you are drilling with a roller type rock bit, you need to apply a very heavy down-pressure. Start a slow rotation of approximately 10 to 20 rpm to cut the rock, assuming that it is very hard rock. The softer the rock the faster the machine would be rotating and the lighter the pressure that would be needed to cut the formation.

You continue on in this manner drilling as you did in the overburden, with one exception. It is important that a stabilizer rod be used, whenever a tricone is used with heavy down-pressure, to prevent the hole from becoming crooked. A stabilizer rod is a short drill rod which is much larger in diameter and, in most instances, has several ridges on it that would almost take up the full diameter of the hole. The purpose of these ridges is to hit against the side of the hole to prevent the hole going crooked by holding the bit perfectly straight, yet still allowing room for the cuttings to come up beside the stabilizer.

In most cases where the rock is very hard you will be drilling with the air hammer instead of a tricone and the hammer tends to take the place of the stabilizer. Also, you could not run the hammer with heavy down-pressure. You would merely keep enough down-pressure on the hammer to keep it from bouncing up rather than having the bit bounce down when the piston strikes the bit.

You will continue drilling in this manner, adding drill rods, until you reach the desired depth or obtain the desired amount of water. As you get deeper into the hole the weight of the drill rods increases the need for applying pressure. At a depth of approximately 200 feet you reach the point where the weight on the bit is becoming too great for hammer use from the weight of the drill rods alone and it then becomes desirable to hold up slightly on the drill rods to prevent their full weight from resting on the bit. Of course as you get deeper it is necessary to hold more and more weight off the hammer.

With either type of drilling, as you go into the hole you find that a heavy cloud of rock dust will be blowing out the top. You should keep this dust away from the pipe to give you a safe footing. Then, depending on which type of equipment being used, you will either start injecting water into the air so that it will travel down the drill pipe and out the bit to cause dampening of the dust to keep it from blowing, or you will have a dust collector from which a suction hose is placed around the drill pipe where it exits from the well. The dust is then sucked into the dust collector and separated from the air. On the dust collector type machine, it is the helper's job to periodically empty the dustbin.

While the drilling is proceeding the bits are usually sharpened, if they are sharpened at all in the field. While the driller is sharpening the bit which was used on the previous job you should observe him carefully to learn how he goes about sharpening bits. A good helper, after a period of approximately two weeks, should be in a position to start sharpening bits under the close supervision of the driller so that he can learn this important part of the drilling operation. When not busy with sharpening bits and emptying the dustbin, you should be cleaning up the tools you have been using. In particular, as soon after the casing is set, you should clean up the bit that was used to drill through the overburden. Both the cutter portion of it, the bearings, and the threaded portion of it should be cleaned. Then apply a thread protector on it and place the bit back on the machine where it is normally kept ready for use at the next job. One of the most important things that a good helper can do is to keep all the hand tools and drilling tools clean and ready for immediate use at all times.