| Multiphase flow through porous media has been an area of interest of many researchers for about sixty years. The difficulties lie in the complexity of solving the governing equation. In the last 15 years, researchers have attempted to use pseudofunctions to simplify and solve the governing equation. This method provides a study for linearizing the governing equation by applying the concept of pseudofunctions (i.e., multiphase pseudopressure and pseudotime) so that the available single-phase solutions can be used. This study shows that since the pseudofunctions are in definite integral forms, the upper and the lower limits of integration must be chosen appropriately. Bottomhole pressure and average reservoir pressure are the lower and upper limits of the multiphase pseudopressure, respectively. A time variable parameter and the forecasted time are the lower and upper limits of the multiphase pseudotime, respectively.;This study is directed towards application rather than theory. We apply pseudofunctions that have been previously developed for the multiphase flow equation to two types of inner boundary conditions: constant total production rate and constant flowing bottomhole pressure. We also tested the proposed method for a pressure buildup test using superposition. Our results show that for both inner boundary conditions, the proposed method works well in some cases and fails for others. In particular, the proposed method produced results with shapes similar to the simulated pressure buildup profiles but the pressure levels were not the same. These discrepancies varied considerably and did not appear correlative. This topic remains a subject for further study. |
