TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractInterpretation of pressure transient data using the derivative curve has proven to be an effective method for quantifying and qualifying well/reservoir information. Analyzing pressure response data affected by multiple rate changes is well understood and readily done using this standard approach. Daily production data (Time-Rate-Pressure) adheres to the same physics and theoretical description as standard multi-rate drawdown data. Therefore, this form of data can be analyzed in a similar manner. This paper shows that the multiple flow rates and pressures forming production data can be transformed into an equivalent single rate data set for direct analysis using standard methods based on the associated derivative curve. The transformation requires nothing more than careful superposition and the calculation of the normal radial flow derivative curve. We show that this approach avoids two of the biggest difficulties with using rate-time type curves for the analysis of production data: the lack of methods for determining the regions in the data representing the proper flow regimes to apply the appropriate analysis, and the calculation of the correct pseudoequivalent production time function.A method for incorporating a derivative smoothing technique is included to improve the ability to interpret field data, which can often be erratic and difficult to analyze. After a brief presentation of the necessary theory, the applicability of this approach using both simulated examples and field data will be demonstrated.

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