Water Well Journal

April 2016

Water Well Journal

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mean a significant cost burden over the life of the well. Improper development can also jeopardize the produced water quality. Reduced or impacted flow, common elements in a poorly developed well, can result in hydrologically isolated zones within the well. These inactive areas often harbor larger populations of anaerobic growth. In addition to nuisance organisms such as sulfate-reducing bacteria that produce hydrogen sulfide odors, many environmental coliforms take up resi- dence in these areas. As long as the flow profile is impacted, the anaerobic pres- ence can continue to haunt produced water quality despite even the best dis- infection efforts. The remnants of drilling fluids within the well and borehole aquifer interface can impact microbial populations too. Many of the polymers used to enhance drilling muds contain phosphates. As the polymers degrade over time, minor phosphate residuals are released into the well, oftentimes resulting in macronutri- ents or stimulants for bacterial activity. The same polymers impacting micro- bial growth can result in discoloration of the produced water, imparting a tint to it from fine particulates in suspension. Beyond an aesthetic problem, fine par- ticulates can be problematic for newer water treatment systems. Membrane filtration, reverse osmosis, and other forms of advanced treatment are particu- larly susceptible to sediment influence. These influences not only degrade the treatment systems, but can cause considerable expense in operation and maintenance. Effective Development Effective development is a function of proper well screen, gravel pack, and wellbore size selection. Improper sizing of any one of these components can have an impact on the development energy transfer needed to maximize the efficiency of the well. Developing efficiency is achieved by the effective application of energy and will more than likely require multiple forms of energy—for example, mechan- ical and chemical—to achieve the in- crease in efficiency desired in a new well. As such, development is a process in which various means and methods are employed with one purpose in mind, which is to make a well as efficient as feasible. Albert Einstein once said, "Every- thing should be as simple as possible and no simpler." In that light, defining development is perhaps easier if consid- ered as "the minimum effort required to obtain the highest percentage efficiency feasible, and no less." There will be a point of diminishing returns, and often that point is when the specific capacity of the well does not increase relative to the amount of time and effort employed in developing the well. Development could also be consid- ered as complete when the well effi- ciency is no longer increasing relative to the effort put into increasing it. If we use specific capacity as a limited anal- ogy to well efficiency, we can then redefine development as being "more complete when the specific capacity is no longer increasing relative to the effort put into increasing it." As stated previously, there is a rela- tionship between the development of efficiency and the time expended to develop it. Lack of sufficient develop- ment time and lack of an effective means of measuring increasing, stable, or decreasing development success are two of the first challenges to proper well development. There is a belief most wells in the same area will take about the same amount of well development, particu- larly rig development time. A recurring theme is a need for effective utilization of enough energy in the correct place, as a foundational concept of well develop- ment. Some individuals hold four to six hours of airlifting a well is sufficient pre-development, and any residual de- velopment needed will be accomplished by pumping. Unfortunately, this is more often not the case. Clear water, or the lack of visual turbidity, is an insufficient indicator of sufficient development. On several oc- casions, downhole video surveys con- ducted in a newly developed well prior to the rig demobilizing from the site re- vealed there was considerable drilling fluid, residual drill cuttings, or fill present in the well. Monitoring discharge from a well under development. Photo courtesy of Ned Marks, Terrane Resources Co., Stafford, Kansas. DEVELOPMENT from page 23 24 April 2016 WWJ waterwelljournal.com A good development program often includes multiple methods, including both mechanical and chemical efforts.

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