Well Performance Prediction of a Well Experiencing Changes in Completion

Well Performance Prediction of a Well Experiencing Changes in Completion T. Marhaendrajana; T. Marhaendrajana Schlumberger Oilfield Services Search for other works by this author on: This Site Google Scholar J. Desroches J. Desroches Schlumberger Oilfield Services Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Gas Technology Symposium, Calgary, Alberta, Canada, April 2002. Paper Number: SPE-75667-MS https://doi.org/10.2118/75667-MS Published: April 30 2002 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Marhaendrajana, T., and J. Desroches. "Well Performance Prediction of a Well Experiencing Changes in Completion." Paper presented at the SPE Gas Technology Symposium, Calgary, Alberta, Canada, April 2002. doi: https://doi.org/10.2118/75667-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 Unconventional Resources Conference / Gas Technology Symposium Search Advanced Search AbstractThis paper presents a new semi-analytical method to predict the production performance of a well stimulated by acid or hydraulic fracture treatment. The new method considers the production history before stimulation, in contrast to current analytical methods that ignore the production history of the "old" well. The initial condition of the "new" well is based upon an "assumed stabilized condition" of the old well.The superposition technique has been extensively used in the literature to model production history (i.e., variable flow rate and variable bottomhole pressure history) and predict well performance. There has not been a detailed study using analytical or semi-analytical solutions that includes the change in well completion (well model change) and that investigates the influence of the production history of the unstimulated well on the well performance prediction of the "stimulated" well. This paper addresses both issues.The semi-analytical method presented here considers changes in well completion, which are becoming more frequent as recompletions become more common. We present validations of this approach using a numerical reservoir simulator for oil and gas reservoirs in which the wells are recompleted with a hydraulic fracture treatment after some initial production.IntroductionThe effect of production history on the analysis of well performance data has been investigated by many authors for years. Horner1 provides a method for treating the variable-rate case based on the application of the superposition theorem. This method requires knowledge of production history as a function of time. Van Everdingen and Meyer2 also presented the use of the general superposition for analyzing pressure buildup data preceded by variable production rate history. More applications of the van Everdingen and Meyer method can be found in Whitson and Sognesand.3 Odeh and Jones4 use a superposition method based on the logarithmic solution, which should be used only during a radial flow regime.The drawback of using full superposition is that the computation is lengthy when there are many significant rate changes. In addition, the complete rate history may not always be available.A simple method was proposed by Horner1 to obtain an equivalent producing time by dividing the total cumulative production by the last established rate, which is later known as material balance time. Although Horner did not present a theoretical justification for this method, it is still used by the majority of reservoir analysts today.The theoretical justification of the material balance time was presented by Blasingame et al.5 The authors showed that the material balance time concept is rigorously accurate for "stabilized flow" or a pseudosteady-state-like flow regime. The lower bound for the start of the stabilized flow is the time to reach pseudosteady state for a constant rate production. This means that any new transient introduced by large changes in rate after this time will eventually die and that stabilized flow will dominate.To our knowledge, the effect of production history has not been investigated for a case where the well completion changes (i.e., the well model changes). This paper examines this phenomenon and provides a semi-analytical method for predicting the well performance under this condition by implementing the material balance time approach. The primary application of this method is the evaluation of the performance of a proposed recompletion.Approximate Solution for a Well Experiencing Changes in CompletionFig. 1 is an illustration of a well experiencing changes in completion. The well model change may represent a conventional vertical well that is hydraulically fractured or otherwise recompleted. Well model 1 refers to the unstimulated well that has been produced up to t = t2, with rates q1 and q2. At t = t2, the well is stimulated and is produced with rate q3. In a case where the well is not stimulated (well models are the same), this problem reduces to a variable-rate problem. Keywords: production control, completion, fluid dynamics, unstimulated well, gas case, permeability, production monitoring, bottomhole, semi-analytical solution, well performance prediction Subjects: Well & Reservoir Surveillance and Monitoring, Reservoir Fluid Dynamics, Formation Evaluation & Management, Flow in porous media, Drillstem/well testing, Well performance, inflow performance This content is only available via PDF. 2002. Society of Petroleum Engineers You can access this article if you purchase or spend a download.

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