Estimating Multiphase-Flow Properties From Dual-Packer Formation-Tester Interval Tests and Openhole Array Resistivity Measurements

Abstract

Summary Multiphase flow and production cuts are affected significantly by relative permeabilities under reservoir conditions. However, their in-situ determination is practiced only in isolated instances, and these have used array resistivity logging. Although wireline dualpacker formation testers provide direct flow tests, analysis thus far has been confined to the determination of single-phase permeability and anisotropy. In this paper, we present a methodology to integrate the formation-tester pressure and water-fraction measurements with openhole array resistivity measurements to obtain zonal relative permeabilities of oil and water. It has been demonstrated previously that the filtrate-invasion process, although uncontrolled, contains quantitative information about fractional flow. The sampling process is similar; it is described by the multiphase/multicomponent flow equations for which the initial condition is set by the invasion process. Geometrically, while the invasion process is largely cylindrical, the sampling process is not. To combine the two, we parameterize the invasion problem in terms of multiphase-flow properties and drilling-fluid loss and carry out a simulation exercise, including generation of resistivity logs. The fractional-flow parameters estimated by matching the observed resistivity logs are then used for modeling fluid sampling with a formation tester. Simultaneous matching of the simulation results with the observed water-cut and pressure data allowed for further refinement of the relative permeability curves. A field example of the application of this methodology will be discussed.