8.6 Production-Well Completion

Production-well completion could easily comprise another chapter, but is included here as a comparison to monitoring-well completion. Proper pro-duction-well completion allows well yields to be maximized while maintaining efficiency. This also leads to confidence in the results from aquifer testing (Chapters 9 and 10).

A general question regarding well completion is: Are we testing the aquifer or the well? An aquifer capable of producing a fair amount of water may be hindered by drilling practices, choice of well-completion materials, or well-development technique. This may result in poor well performance. Another type of problem arises when well-completion materials are preselected before there is a proper knowledge of the aquifer properties. A slot size or packing material is used that is similar to other wells in the area when they may not be appropriate. This is an inefficient use of resources. Just because a well may be designed to yield a particular quantity of water, the aquifer may be incapable of doing so.

The best way to tell what the aquifer is like is to drill a small diameter pilot or test hole. Larger-diameter production wells can then be drilled with a good knowledge of where the production zones are. If the cable-tool drilling method is used and the target aquifer is known to be productive, production diameter casing may be used from the beginning. This approach can also be used for "drill and drive" rotary methods. Samples from the production zone can be collected and analyzed to...