In my experience, the most popular method of developing wells drilled with a cable tool rig is the surge block. This tool, in cross section, looks like a hamburger sandwich with steel plates as the bun and a piece of rubber belting or similar material as the burger. Some surge blocks are made like a double decker hamburger with 3 steel “buns” and two “burgers.” This tool is attached to the cable tool string in place of the drill bit and lowered into the well below the water line. Then, the spudding action is started. This tool supposedly moves the water in the well and the well screen back and forth, breaking up bridges of sand and bringing finer particles into the screen.
Bailing and jetting are two popular development methods available to drillers. Source: iStock
Blocking and Bailing
After running the surge block for a period of time—and experience dictates what this time is, the driller removes this tool and goes down inside the screen with the proper size bailer and removes accumulated sand. The surge block is then run back in and used another time, followed by bailing, followed by more surging until little or no sand enters the well screen. The well is then test pumped until clear, the capacity gets noted and the development process is over.
I have a surge block and, frankly, never had a whole lot of success with it. Did it improve well capacity? Yes, it did to a certain degree, but never what I had hoped for. I often wondered if my block was made correctly, but it sure seemed to be made according to drawings and information I was able to access. Another point here is to be careful with the bailing process inside the well screen; this is especially true if the well has a high static level. I once completed a domestic well in a difficult area where wells were commonly too shallow to be safe or produced a very minimal amount of very bad water. Neither of these conditions was very desirable.
I managed to find a good sand and gravel aquifer at a little over 100 feet. The static level was about 5 feet below ground surface and the well had good capacity for the size of casing I had used. I had successfully test pumped the well and decided to go down in the screen to clean out any accumulated sand. After doing this, I ran my dart valve bailer, which is intending to bail out twice the capacity of the casing, and the job would be done. Much to my chagrin, I bailed the casing empty. Careful measurement indicated that I had “sucked” the screen up into the casing its full length where it would produce no water at all.
I had to reset the screen after pulling it out using a handy-dandy little tool shown to me by a good driller friend who is now running a well rig in the sky or, perhaps, heaven. The lesson learned is that if you are going into the screen with a bailer, come out very slowly until the bailer clears the screen body and riser pipe, and then you can bring it to the top at full speed.
Another method of developing screens is the use of a jetting tool. I have been told by people that I respect as knowledgeable about drilling that this is “the way” to develop. This tool is a short piece of pipe that is plugged on one end and into which small holes are drilled. It is attached to the bottom of either regular steel pipe or drill pipe. The tool is lowered into the screen and a pump at the top pumps water under pressure through the holes, through the screen and out into the formation. This supposedly loosens up the formation. The drawback of this system is you have to have an external source of water to feed the pump. The pipe is rotated and the tool is slowly brought to the top of the screen in steps.
After a period of jetting the tool is withdrawn to the surface and the screen cleaned out. This jetting can also be accomplished using compressed air, and that is a favorite of rotary drillers using the mud method. Another important factor in this system is to have a pump with high pressure capability; I have a tool like this in my inventory and, frankly, never had much success with it—at least not the success I hoped for. I think the pump I used was not nearly as robust as it should have been.
Probably every driller has his own pet method of development and some are pretty unique. My dad and I rigged up a Rube Goldberg system for 4-inch wells that included 2-inch drop pipe with 4-inch leathers attached, one facing up and one facing down. This was attached to the bottom of 2-inch drop pipe with a section of smaller pipe going down into the screen. We lowered the leathers until they were near the top of the screen and then put a plunger down in the 2-inch pipe and went to pumping out of it, but only after we suspended our drop pipe on the front spring from an automobile.
In action, this thing looked like the brain child of a mad scientist. But it worked. It was especially helpful when pumping after introducing phosphates into the formation to break up native clays. The use of this product, phosphates, is a whole other subject that I am not going to get into. Perhaps someday in the future or, if you are really interested, you can contact me through National Driller and we can talk about it or write back and forth. Using this tool, either with phosphates or not, we had cases where we increased production to 10 times the original and, to be fair, we had a few cases where it appeared to do no good at all.
I have gone to some length on this subject and could possible write a small booklet about screen development. I am going to quit this topic right here and move onto some other things that are not very popular anymore, although they still work. I will leave readers guessing what those things are and you can read about them in my next column.
As this is written in late January, we have had some really strange weather in Michigan. About 10 days ago, we had a huge snowstorm coupled with high winds and actual temperatures of 15 to 20 degrees below zero Fahrenheit. I had a drift 22 inches deep across the front of my shop, over 80 feet. A few days later most of this melted in 40-degree temperatures and the unpaved roads turned to mush and mud. Today, it is about 12 degrees and we have had more snow so the ground is pure white—not the best weather to be drilling in.