How many ways can you build a water well? Water wells can be drilled using the open-hole, packer, or gravel pack method. Probably as many as there are wells, but generally speaking, there are three types: ...
Probably as many as there are wells, but generally speaking, there are three types:
The first type is open-hole completion. Usually, an open-hole completion is when you have casing that is installed to keep the well from collapsing. It also helps to keep out contaminants. It's set inside the bore hole. Surface-cased wells are wells that the casing extends just below the surface usually 10 or 20 feet deep. A surface completed well could have a 10 foot casing in it or it could have a 360 foot casing in it. The actual production, the rock or the sand or whatever they produce with the water is left uncased, and it simply migrates into the bore hole and is there available to the pump. It doesn't have to go through any casing; it just falls into an empty hole. That can be done in areas where you don't have a big problem with collapsing wells.
The next type of completion of well is called a packer method. A packer completion method is where a well is cast all the way to the bottom of the hole. That's where we still have the 400 foot well with the water produced from 360 to 400 foot. We would put perforations in the casing in that section between 360 and 400 foot. If the water could travel into the bore hole into the perforations in the casing, it would be available inside the casing to be formed. Usually if this is done, we would use what's called a packer or a shale trap on the outside of the casing. Its job is to catch any contaminants, any kind of cave-ins or anything like that.
The third type of completion is the most common. It's called gravel pack. You usually have to drill little bit larger diameter holes for a gravel pack well. You set your perforated casing down where the water is produced. The perforations are tiny holes a hundredth of inch or two hundredths of an inch in thickness, and you don't have any kind of packer on the outside of the casing. Okay. But you pull gravel on the outside of the casing. If that gravel migrates down and sits between the bore hole wall and the casing wall, it will stop any solids like clay or sand from migrating into the casing. Any water that tries to migrate though goes right to the gravel and into the casing. On top of the gravel you will usually only gravel pack to 360 or 340 feet (just to the water producing zone on the outside of the casing). Then on the inside and above the gravel you will place either a clay field or a concrete field to keep anything like contaminants or sewage from migrating down the outside of the casing and getting into the production area.
