A Downhole Flowmeter for a Better Definition of Well Hydraulics

The Electromagnetic Borehole Flowmeter (EBF) provides a new, simple, cost-effective method for determining the vertical profile of horizontal influx into a well in granular media and groundwater flow in fractured rock. Flow data are recorded at discrete positions in screened wells or uncased boreholes. Vertical resolution of one-foot increments is typical, but the system can be used in a trolling mode to provide a continuous trace. The EBF uses a basic law of physics, Faraday's Law of Induction, to measure flow rates in a well. Through complex signal processing, the instrument system detects extremely low flow rates and also measures flows over a wider range than other available flowmeters. It is designed for testing in wells with a diameter as small as 5.08 centimeters (two inches). This instrument system has been used to record the influx distribution in water supply wells, but it has been used primarily to support environmental studies of contaminated groundwater.