Completion procedures in the Permian Basin, especially in limestone, dolomite, and reef formations, can be tremendously important in determining a well's producing rate and economic return. Every well should be considered as a separate problem, with due thought given to the need for control. Among the controls which should be provided by the completion procedure are control of gas, control of water, control for completion treatments, control for secondary recovery, control of work over costs, and control of expense during completion and subsequent production.
Engineering analysis and mature thought should be used in order to obtain the best possible completions.
Oil was first found in West Texas approximately 30 years ago when almost all drilling was done with cable tools. Most of the early drilling was done on surface-indicated structures, and the pays found were shallow. The wells were drilled without fluid in the hole and, on many of the more prolific wells, the first indication of the pay zone was the sight of the tools blowing out of the hole.
Extensions to these fields were completed by setting pipe above the pay zone, and then drilling in with cable tools. Because many of the fields discovered early in the development of West Texas have very effective vertical and horizontal permeability, a well completed in them did not have to do much more than scratch the top of the pay in order to get at least fair drainage to the well bore. If the pay had a rather high pressure, it was often impossible to do much more than scratch the top of the pay before the well started producing. If the field had a natural gas cap, it was common practice to allow the well to blow gas to the air until the gas cap was dissipated and the well started making oil.
Logging on these wells was of the most elementary type and drillers' logs were often the only information that was available to show the productive zones. This caused many people to feel that there might not be drainage of any zones not left in open hole since they could not be certain of the location of these productive zones.