Evaluation of Pressure Derivative Algorithms for Well-Test Analysis Freddy Humberto Escobar; Freddy Humberto Escobar Universidad Surcolombiana Search for other works by this author on: This Site Google Scholar Juan Miguel Navarrete; Juan Miguel Navarrete Hydrocarbon Services Ltd. Search for other works by this author on: This Site Google Scholar Hernãn Dario Losada Hernãn Dario Losada Hydrocarbon Services Ltd. Search for other works by this author on: This Site Google Scholar Paper presented at the SPE International Thermal Operations and Heavy Oil Symposium and Western Regional Meeting, Bakersfield, California, March 2004. Paper Number: SPE-86936-MS https://doi.org/10.2118/86936-MS Published: March 16 2004 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Escobar, Freddy Humberto, Navarrete, Juan Miguel, and Hernãn Dario Losada. "Evaluation of Pressure Derivative Algorithms for Well-Test Analysis." Paper presented at the SPE International Thermal Operations and Heavy Oil Symposium and Western Regional Meeting, Bakersfield, California, March 2004. doi: https://doi.org/10.2118/86936-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Western Regional Meeting Search Advanced Search ProposalPressure well tests performed during any stage of the life of a well are a very important tool to obtain fundamental reservoir characteristics. Also, they are one of the closest views obtained from the reservoir. Well testing is so important that an estimative of hydrocarbon reserves can be obtained. Also, it is possible to determine reservoir flow capacity and distance to discontinuities, among several applications.Currently, pressure derivative analysis used in well testing is a very versatile procedure for reservoir characterization. However, this parameter is affected by the noise produced by turbulence, the tool itself, and the mathematical procedure involved. Therefore, it is important to properly use numerical tools to filter data. The pressure derivative function has become the most popular technique to interpret well pressure data but it suffers of noise since it is based on numerical differentiation on discrete pressure data points. The threepoint central-finite different scheme has been widely used to estimate pressure derivatives. Noise occurs when consecutive points are used. It makes difficult to carry out an interpretation. Then, it is convenient to choose points further separated from each other to reduce the noise. However, if the points are so apart, the pressure derivative will be distorted. The Spline function is a powerful tool to calculate pressure derivative data for well test applications. Its continuous character and its polinomial behavior make it very effective to mitigate noise. It matches well to the expected form of the curve.In this paper, an evaluative analysis of the pressure derivative is presented. It is performed by comparing the results from different algorithms (Spline, Bourdet, Horne, Simons, Clark and Van Golf-Racht, first degree and second degree polynomials), and observing theoretical pressure vs. time data with those provided by the chosen analytical solutions. It was found that the Spline function provides the best results to estimate pressure derivative data. Besides, the recommended procedure consists of differentiating the data and, then, filtering and/or smoothing them.INTRODUCTIONCurrently, application of pressure derivative to analyze well pressure test is one of the most versatile procedures. However, pressure derivative is affected by the noise coming from several sources; therefore, it is so import to define the most appropriate algorithm to estimate pressure derivative and to use adequate tools for data filtering.The oil industry has been exposed to recent technology advances involving both higher pressure recorder resolution and the versatility to handle the information. This makes the information processing to be a much shorter task than it used to be.In spite of these achievements, it does not exist a procedure to indicate a clear way to analyze the information. Actually, there are several mathematic algorithms to calculate the pressure derivative curve as a function of time for well pressure analysis, but there is not certainty in either the optimum method and the criteria to appropriately utilize them.Basically, the purpose of this work is to analyze the most common methods reported in the literature to calculate the pressure derivative function with and without noise effect. The impact of filtering the pressure data was also studied. Comparison of numerical pressure derivative for different reservoir and well configurations to analytical pressure derivative was performed to observe the deviation error between these two parameters. Keywords: noise, vertical well, average error, procedure, spe 86936, algorithm, derivative behavior, pressure transient testing, pressure derivative function, horne Subjects: Formation Evaluation & Management, Pressure transient analysis, Drillstem/well testing This content is only available via PDF. 2004. 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