PUMP DEPARTMENT
Anderson Water Services
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| Pumping Test and Well Yield Under the heading "Bailing or Pumping Test" on older logs or "Well Test" on newer logs are the parameters necessary to help establish the initial efficiency of your well. These parameters include: the Test Rate, Pre-Pumping Static Level, Feet of Drawdown and Duration of Test. The Test Rate is the rate in gallons per minute that water was either pumped or bailed from the well. A bailer is a long tube the driller uses to remove water and/or sediment from the well. The Pre-Pumping Static Level is the level to which water has stabilized in the well with no outside force acting upon it (the well is not pumping water). Subtracting the static water level from the total depth of the well results in the feet of water in the well. A five inch diameter well will store approximately one gallon per foot of water while a six inch diameter well will store approximately 1.5 gallons per foot of water. Feet of drawdown refers to the difference in feet between the pre-pumping static water level and the final pumping level measured by the driller at the end of the well test. For example, if a well has a 50 foot static water level and a final pumping level of 75 feet, the Feet of Drawdown would be 25. If the water level remains constant during pumping, the water is being replenished at the same rate it is being pumped. This would be a very efficient well. In general, wells with lesser drawdowns will be more efficient wells. Wells with higher or total drawdowns are often very inefficient, low yielding wells. The "Duration of Test" is A cone of depression is formed whenever a well is pumped. This cone of depression is best described as a three dimensional cone surrounding the well that represents the volume of water removed as a result of pumping. This cone is deepest and steepest near the wellbore and flattens out as distance from the well increases. Generally speaking, the larger the withdrawal, the larger the cone. Since no two cones of depression are ever identical, it is necessary to perform a pumping test to determine the size and shape of the cone. The figure below illustrates these concepts. |
| Submersible pumps is a pump which has a hermetically sealed motor close-coupled to the pump body. The whole assembly is submerged in the fluid to be pumped. The advantage of this type of pump is that it can provide a significant lifting force as it does not rely on external air pressure to lift the fluid. Working principle ESP systems are effective for pumping produced fluids to surface. A system of mechanical seals are used to prevent the fluid being pumped from entering the motor and causing a short circuit. The pump can either be connected to a pipe, flexible hose or lowered down guide rails or wires so that the pump sits on a "ducks foot" coupling, thereby connecting it to the delivery pipework. |
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