The purpose of this appendix is to present a simple simulation example of a two-zone, single-phase interference test (Fig. A-1), which can be run in just a few seconds on most simulators. This is an example of an interference test between an active well with variable injection and production rates and an offset observation well in a different zone. The model input (including a simple Cartesian grid) can be obtained from the authors for testing of various matching algorithms. It has a number of unknown parameters such as the area and transmissibility between the two zones, which must be determined through history matching because it cannot be easily solved analytically. The number of variables to be determined is quite small, so it lends itself to many different history-matching algorithms. An experienced reservoir engineer should be able to obtain a match in a few hours. The only data to match is the pressure of an observation well. The history-matching parameters to be varied would be (1) net pay, permeability, and gas porosity of the two zones, (2) initial pressure, and (3) location and transmissibility of communication between the two zones as illustrated in Fig. A-1. Fig. A-2 illustrates a simple Cartesian grid that can be used to obtain a match.

For this example, there is little ambiguity on what most engineers would consider a good match. Fig. A-1 shows a high-quality match. The pressure trend and absolute values should be matched within a few tenths of a psi pressure difference over all times. Fig. A-3 shows sensitivity of model pressure to changes in various parameters. Appendix B provides an example automated history match for this problem. The manual case shown here and the automated case shown in Appendix B provide two possible solutions. The final parameters are not given so as to not bias alternative approaches.