Interpretation of simulated falloff tests

A study was made of the method for determination of swept volume and the proper average temperature to use for interpretation of combustion falloff data using the ''pseudo-steady'' state concept. Two thermal simulators were used for this study to include non-uniform reservoir temperature and variable saturation effects. Skin and storage effects were not included. Interpretation of the data was based on the finding that, because of the very large contrast between the conductivity of the gas in the swept volume and that in the unswept sand ahead, transient effects caused by the swept volume would be characteristic of a section of very high transmissivity (kh/..mu..). This implied that the transition period characteristics of the falloff data will form a straight Cartesian line whose slope will be related to the swept volume. This follows from the concept of ''pseudo-steady'' state. Results obtained from the analysis of simulated data showed good agreement between calculated swept volume and actual swept volume. However, the swept volume was found to include both the burned volume and also the high gas saturation zone ahead of the combustion front. Thus a volume correction is necessary to relate the swept volume to the burned volume. In addition, averagemore » temperatures within the swept volume were calculated so that the appropriate physical properties can be included in the interpretation. Graphs which can be used to make these corrections are presented for use in interpreting similar field falloff data. Although a one-dimensional radial model was used for this study, the concept should apply in multi-dimensional cases where gravity override is common.« less