Assessment of Water Well Drilling Challenges in Ethiopia
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Date
2018-06-30
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Addis Ababa University
Abstract
The purpose of this study is to identify the main water well drilling and completion problem and explore viable solutions, in Ethiopia. The scope is limited to literature review, data from private and governmental drilling and consulting companies, technical training institutions and discussion with senior drilling professionals.In general 216 selected boreholes with the typical drilling problem were identified throughout the country with their GPS coordinates, target drilling depth and aquifer type. Analysis was made to categorize which kind of structural and hydrogeological setting is most vulnerable for the recorded well drilling challenge. The most prevalent drilling problems happened in Ethiopia include Well caving, drillpipe stacking, lost circulation, hole deviation, drillpipe failures, hole cleaning and personnel and equipment related problems.
Among the problems investigated in this paper, the main Ethiopian rift valley and the Tana basin are the areas with highest frequency of drilling challenges are encountered. Among the drilling challenges, well caving stands out as the major drilling challenge with 26.3% of the total occurrence. The frequency of lithology also clearly showed that 45% of drilling problems happening in Fractured and weathered basalt aquifer. Moreover, discussions with chief drillers and hydro-geologists in the field also unveiled the most of the drillers operating in the field lack basic standard training on the drilling of boreholes with various methods of drilling, using appropriate drilling fluids and troubleshooting when the major drilling challenges encountered on the field.
Hence, water well drilling crew and supervising hydro-geologists must have a proper acquaintance with different kinds drilling system. Furthermore, typical drilling fluid consumables which are highly recommendable for drilling of wells in different geologic and structural settings must be identified and accepted by the clients. The water well drilling firms and their technical staffs must also be familiar and willing to apply drilling fluids and polymers in order to minimize the risk of abandoning and failure of borehole construction. Selection of quality casings and screens are also crucial to minimize drilling challenges such as casing and well collapse. The technical specifications of drilling projects must also incorporate consideration of local hydrogeology and geological structures to prepare well designs and to select drilling methods and consumables.
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Assessment, Water Well, Drilling Challenges, Ethiopia