Estimation of naturally fractured oil reservoir properties using the material balance method

In fractured reservoirs, a large variation of permeability due to the presence of fractures leads to changes in the production mechanism compared to conventional reservoirs. Hence, an appropriate model with the ability to describe the reservoir properly can provide a more confident prediction of its future performance. One of the features of a representative model is the number and height of the matrix blocks. The determination of these two parameters is one of the decisive steps in the calculation of an accurate amount of oil production from these reservoirs. In fact, matrix height shows its effect as a gravity force, which is one of the driving mechanisms. If the matrix height is less than the threshold height, it will have a significant inuence on production. The aim of this study is, therefore, to obtain mathematical relations that are able to estimate the matrix height from material balance analysis. In this study: (a) The Havlena and Odeh straight line form of the material balance equation has been extended to analyze the behavior of naturally fractured reservoirs, and (b) Equations that can be used to estimate the matrix height are obtained for the Warren-Root and Kazemi models.