Double Porosity Model with Transient Interporosity Flow for the Response of Tracers in Naturally Fractured Reservoirs, Considering Constant Mass Flux Injection

Abstract

In tracer test interpretation, fissured reservoirs are commonly referred to as double porosity systems: different approaches have been proposed for analyzing their well tracer concentration responses. This work presents a double porosity model with transient fracture-matrix transfer using constant massic flow for the interpretation of the observed tracer response in the producing wells for continously injection of a tracer.

A new parameter is presented which represent the gradient of mass flow that governs the transfer fracture-matrix and it is used to characterize the porous media. The solution was obtained in Laplace¥s space for the proposal mathematical model. The numerical inversion was carried out with Stehfest¥s algorithm
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The values of the numerical inversion were used to generate the “type curve”, presented in terms of the dimensionless groups obtained from the approximate analytical solution. Ekofisk field data was matched to this tracer response type curve to determine parameters of practical interest, such as size block matrix, “in situ” mixing coefficient in the fractures.