Jetting Gravel-Packed Wells 2

Install the undercutter and necessary drill pipe in the drill hole and attach the circulation water hose. Lower the undercutter to the area to be worked and turn on the water pressure. A suitable amount of drilling compound must be kept in the work water. This tool is worked slowly up and down and turned back and forth to undercut the desired opening for the gravel pack.

While this is being done, the well screen, well pipe and gravel are being prepared for installation. When the undercutting is complete, the pipe is removed slowly from the drill hole, at the same time, being sure to keep the drill hole filled with water.

Install the well screen and well pipe in the well and secure at proper placement. If the well is shallow, the water hose may be connected to the top of the well to slowly pump some water through the screen. Uniform gravel may be poured evenly down the side of the well or down a tremie pipe if deeper. It may be better to pump the gravel through the inner pipe and bottom valve until the desired level is reached some dimension above the screen area. Then remove the inner gravel pipe. It may be desirable to install a gravel fill pipe for future needs before filling the space between the well pipe and the drill hole.

If no casing is used, mix clay with the drilling mud from the well and pack the well between the well pipe and the drill hole - or fill the area with concrete mix to the surface. The starter casing may be removed if desired.

Next, pump some water from the well. It is desirable to wash the gravel and sides of the drill hole and start the flow of water as soon as possible. The amount of development needed varies, but it must cleanse the drill hole walls and the gravel to develop the flow. Development must be continued until the well is sand free.

After pumping some water and cleaning the well with the pump, it is desirable to fill and pump the well several times. A high-pressure water jet, made similar to the undercutter to fit in the well screen, is excellent for cleaning the sands and mud pack from the drill hole walls. This is repeatedly worked up and down and continuously turned to force high pressure water out through the screen and back in, above and below the tool. It is also helpful if some additional water is pumped from the well at the same time. An air jet blast through the same tool at the same time also aids the process.

If more development is needed, a surge plunger will help to set the sands and aid development. It is sometimes necessary to use chemicals to dissolve and help remove substances from the well and water veins. After development the well should be thoroughly disinfected with the 50 ppm chlorine solution and the well capped or plugged until the pump is installed.

There are many ways to employ jetting principles to water well work; these have been some of them.