In-well hydraulics of the electromagnetic borehole flowmeter: Further studies

The electromagnetic borehole flowmeter (EBF) is finding increasing applicat ion as a method for measuring hydraulic conductivity (K) distributions. A r ecent paper details an experimental/theoretical study of the effect of in-w ell hydraulics on calculated K distributions based on EBF measurements (Din widdie et al. 1999). Results showed that minimizing head loss associated wi th flow through the meter was the key to producing accurate K values. Using the same experimental procedures, the previous study has been extended to develop data from a larger diameter (1 inch) EBF, and to determine if an EB F can be calibrated effectively without using an inflatable packer to force all flow through the meter annulus. Both experiments were aimed at produci ng low head loss conditions. Results show that overall calibration can be a ccomplished in the absence of a packer, which reduces head losses to nonmea surable levels, and use of the 1-inch EBF with a packer reduces head losses by a factor of 16 when compared with the 0.5-inch EBF studied by Dinwiddie et al. (1999).