f Water well diagnostics

Wells are constructed for different purposes: water production, water injection, water level monitoring, water sampling, etc. Usually geological-hydrogeological planning, occasionally surface geophysical investigations, and well-logging measurements precede location and construction of wells. It is necessary to check the constructed wells several times during their lifetime. Immediately after construction it should be checked whether the well construction fulfills the specification described in the technical plan. Producing water wells should be checked regularly (in every 1-5 years according to the standards of different countries) from the point of view of construction, hydrodynamics and water/gas composition. When a change (above all deterioration) takes place in the well’s condition (the yield decreases, silting occurs, the water temperature changes, the water level sinks, etc.) checking measurement is required and based on this an intervention (change in operation, well repair, etc.). The original parameters of a well might be uncertain in the case of old wells. When the ownership changes or the purpose of the well’s operation is modified checked well data are required, therefore it is advisable to perform a complete set of well diagnostic measurements. Tools of production geophysics provide a possibility to carry out these investigations correctly. Some characteristic, interesting cases are presented, these demonstrate the wide variety of measurements executable in wells and the large amount of information obtainable in connection with well operation and well repair.