Design, operation, and data analysis for a wireline packer system in open boreholes, with field-test results from Belvidere, Illinois

A wireline-operated packer was designed for use with a standard geophysical logging system. The packer probe consists of a downhole packer inflated with water removed from the borehole by an in-line submersible pump, and a differential pressure transducer calibrated to measure the hydraulic-head difference between the zones above and below the packer. Analysis of the packer data is based on a numerical model that predicts the water levels above and below the packer for a given set of aquifer zones of specified hydraulic head and transmissivity. Various computations are used to indicate the sensitivity of the packer measurements to the hydraulic head and transmissivity contrasts between aquifer zones.

The wireline-packer probe was field tested in a series of open-bedrock boreholes in Belvidere, Illinois, at a site where vertical hydraulic-head differences are produced in a horizontally stratified aquifer by water production from an underlying aquifer. Analysis of the wireline-packer data produced estimates of hydraulic-head gradient and aquifer-zone transmissivity consistent with results from straddle-packer hydraulic tests. However, the wireline-packer data also indicated that there are significant variations of vertical hydraulic gradient with depth, and that the gradient is sharply reversed near the bottom of the boreholes. This result is consistent with upward ambient flow measured on previous occasions near the bottom of these boreholes, and has important consequences for the monitoring of ground-water flow at the study site.