Abstract

This study presented the pressure behaviour of a well located in multilayered bounded square and crossed by a vertical fracture (uniform flux or infinite conductivity). It was found that pressure function and its derivative and fractional flow from different layers are mainly controlled by the fracture extension into the formation. The effects of transmissibility and storativity on fractural flow and pressure derivatives are significant. Such effect on pressure functions are insignificant. Therefore, type curves of pressure functions can not be used in evaluation reservoir characteristics while those of pressure derivative can be used for this purpose. The nature of the fracture was found to have minor effects on different parameters included in this study. It was found that type curves of buildup pressure function can be used only for very small values of fracture extension and production time.

Introduction

The literature review presented in Reference 1 indicated that many papers were published handling the different situations of multilayered reservoirs2–12 while others treated fractured homogeneous reservoirs13–20. None of these studies treated the case of fractured multilayered bounded reservoirs. Such reservoirs are common, although. The thickness, permeability and the porosity may vary from layer to layer. Thus differential depletion might exist between different layers. It is of prime interest to have a technique to analyze test data of such reservoirs. A previous study treated the case of infinite acting reservoirs1. The main aim of this study is to handle the case of a vertically fractured well located in a bounded square drainage area, the mathematical equations were developed to express the pressure and its derivative for both drawdown and buildup testing and fractional flow from different layers. Type curves for pressure for different reservoir conditions. A test example is presented to show the application of the techniques presented in this study.

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