A well test is an evaluation of a well to learn more about its production capacity and the characteristics of products drawn from the well. This term typically refers specifically to testing water wells, but it is also possible to perform tests on oil and gas wells. Firms specializing in well testing can offer a variety of services to customers and are often willing to travel to reach remote well sites. Fees for testing can vary depending on the types of tests that are necessary.
With a water well, one important concern is how much the well can produce. As the pump operates, pulling water out of the well, the water table starts to drop, a phenomenon known as drawdown. It is possible to draw down the contents of the aquifer too quickly by operating the pump at maximum capacity and draining the well dry. In a well test, a firm can determine how much water the pump can safely draw at any given time, pulling water out while allowing the aquifer to recover.
This results in a rating, providing information about the pumping capacity of the well. This can vary at different times of the year, such as during a dry season, when the water table drops more quickly because there is less water available to refill it. The well test determines how many households the well can reasonably supply. Testing technicians may also have concerns about depleting the water table to the point where neighboring wells cannot function, and must consider the needs of all households drawing on the aquifer, not just one.
It is also possible to conduct a well test for water safety. Testing firms can check for bacteria and other microorganisms along with contaminants like radon gas and chemicals. The company may test the water if the well owner has concerns about odor or color, or in response to health problems. This well test can include an inspection of the well to pinpoint the source of a problem and provide recommendations on addressing the issue.
Well test companies employ hydrologists, biologists, and other technicians with experience in water wells, water safety, and related topics. It may be necessary to test a well for capacity before it can be approved by building officials, and periodic testing to check on water safety is a good idea, to catch issues with the well water before they become a problem.
Oil and gas well testing involves similar activities to determine the capacity and quality of production. Petroleum engineers typically head up testing teams to evaluate new wells and examine older wells to determine which steps, if any, the company should take to repair a well or stimulate it to increase capacity.