COMPARISON OF THE FLUTE HYDRAULIC CONDUCTIVITY PROFILING RESULTS WITH STRADDLE PACKER MEASUREMENTS

The FLUTe technique for location and mapping of the significant flow paths in a borehole using a flexible everting liner was reported earlier in several other papers. The method maps the significant flow paths in a borehole in 1-4 hrs. relatively independent of the borehole depth or diameter. The location of each flow path (e.g., fracture, or bedding plane) and the explicit measurement of the flow rate in each path in such a short time with the everting liner (10-15% of the typical time for discrete straddle packer testing of the entire hole) has obvious utility. However, the question is whether the FLUTe measurements are correct. This paper describes the techniques that have been developed to assess the FLUTe method and to make a careful comparison of FLUTe results with the packer tests of the same borehole. The FLUTe measurements provide much more spatial detail than discrete packer tests and therefore the FLUTe measurements were integrated over the same vertical interval as each packer test to provide the equivalent average packer value. The differences are obvious. The next step was to use the packer conductivity profile to calculate a synthetic liner vertical velocity in the borehole. The packer data provided a substantially higher synthetic liner velocity than the FLUTe liner measured velocity. A test of the comparison was performed by integrating the FLUTe data to provide an equivalent set of packer results, and then using the integrated FLUTe results to develop a synthetic liner velocity for comparison with the actual liner velocity measured with hole depth. The comparison was nearly perfect, suggesting that there are no errors in the comparison methods used. The conclusion is that the straddle packer testing provided excessively high conductivities in the highly fractured regions of the boreholes due to leakage past the packers. There is no leakage component in the liner measurement method. The everting liner measurement method seems to provide more accurate results than the packer testing for highly fractured holes. However, the straddle packer tests can measure to lower conductivities in the low flow regions of the borehole than are practical for the everting liner method. The low cost of the everting liner measurement method and the data quality should provide a significant advantage in remediation and monitoring designs.