This paper presents new analytical solutions to unsteady state and pseudo-steady state flow in naturally fractured reservoirs whose boundaries can better be approximated by elliptical rather than linear or radial coordinates. While elliptical flow may occur in several geometric systems, fractured reservoirs are believed to exhibit elliptical flow behavior, particularly during the transitional period. Directional permeability inherent in fractured reservoirs creates reservoir anistropy. Flow from anistropic reservoir towards a circular wellbore will be elliptical rather than radial.

In this study the pressure pattern of naturally fractured reservoir is considered to develop under the assumption that allows matrix to fracture cross flow to result from a diffusion mechanism of fluid transfer through the matrix. The constant rate pressure distribution equations developed in this study were coupled to skin and wellbore storage parameters.

Type curves which can be used for well test analysis were generated with results of various analytical solutions. In the second part of this study, presented in the part two paper several field pressure data were analyzed using these type curves and the results compared with those obtained from type curves generated using radial or linear model solutions.

You can access this article if you purchase or spend a download.