This paper introduces a strategy and methodology for the wireline measurement of permeability that is consistent with the geological structure observed at the wellbore. The strategy involves new technology; real-time data acquisition and interpretation in parallel utilizing high resolution borehole images and a multiprobe formation tester. The multiprobe tester differs from its single probe counterpart in that it has an additional two probes, displaced from the flowing probe, at which the pressure is monitored. In homogeneous formations this configuration permits the direct determination of both horizontal and vertical mobilities; in laminated formations such a tool allows the study of potential permeability barriers and their effect on vertical fluid movement. As part of the method, we introduce a new interpretation for the multiprobe tester based on flow regime identification using the pressures obtained at the observation probes.
Application of the method is demonstrated using data obtained from two field tests. In addition to electrical and nuclear logs, electric borehole images were obtained over the intervals of interest. The borehole images were used at the wellsite to identify several potential barriers to vertical flow and to choose the test points for the multiprobe formation tester. Subsequently these intervals were tested to determine the effect of the barriers on vertical communication. Additional multiprobe measurements were made in relatively unstratified zones to allow a comparison.
The results of one example indicate that features appearing as permeability barriers at the wellbore may not have large lateral extent and therefore do not act as barriers to vertical flow. The other example shows that the converse may also be true, in that, features which are observed to be thin at the wellbore can have considerable lateral extent and be significant barriers.