Existing pressure test solutions for naturally fractured reservoirs neglect the macroscopic pore system permeability, the wellbore storage and skin factors of the observation wells, and are limited either to single-swells in infinite domains or to concentric wells in circular reservoirs.

In this paper, two solutions for interpreting interference pressure tests in naturally fractured reservoirs are presented. The model on which these solutions are based incorporates both macroscopic fracture and pore system permeabilities, an improved unsteady interporosity flow model, and allows for wellbore storage and skin factors of the wells. In the first solution, the pressure response of a shut-in observation well to arbitrarily varying unsteady pressure fields is considered under the assumption that the observation well affects the flow field only locally. In the second solution, a general technique for exactly solving the governing equations for fluid flow in naturally fractured reservoirs with multiple non-concentric circular boundaries is first developed. The procedure is then specialized to two circular boundaries to determine the pressure changes induced in a circular reservoir by an eccentric flowing well with wellbore storage and skin. These two solutions, used together, will enable the development of pressure tests for determining the location of the center of a circular reservoir in addition to its radius and its hydraulic properties.

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