Applications of Harmonic Pulse Testing to Field Cases (SPE 154048)

Harmonic pulse testing is a well testing technique in which the injection or production rate is varied in a periodic way. The pressure response to the imposed rates, both in the pulser well and in the observer wells, can be analyzed in the frequency domain to evaluate the reservoir properties. The advantages of this type of test is that dedicated well testing surface equipment is not required and that the test can be performed during ongoing field operations. In an earlier study we demonstrated that the harmonic pulse testing methodology can be used to evaluate the development of effective permeability and total compressibility even for such a heterogeneous case as resulting from a water injection scenario. The analysis can be performed using a numerical simulator in the Fourier domain, by which heterogeneities can be explicitly taken into account. As time-stepping is not required in such a simulation, the calculation can be performed much faster. In the present paper we report on the application of the methodology to two field cases. In the first case a gas storage reservoir was operated with a day-night injection-shutin scenario. Data analysis could prove that the reservoir was homogeneous and that a minor fault identified by the seismic was not hindering hydraulic communication between the pulser and the observer wells. The second case was a harmonic test experiment in three groundwater wells which was reported earlier, but where the analysis was inadequate. The theory used was insufficient to consistently explain all the measurements, likely to be affected by strong reservoir heterogeneity. Only with our novel methodology it was possible to investigate the effects of heterogeneity. We demonstrate that a heterogeneity in the form of high-permeability streaks adequately describes the test results.