WTFM – Pumping tests in fractured media

Identifying hydraulic characteristics and transport properties of fractured reservoirs requires development of specific models that take into account (i) heterogeneity of environment, i.e. presence of major conductive fractures, which delimit capacitive matrix blocks containing weakly open, dead-end or isolated fractures, and (ii) geometric arrangement of major conductive fracture network, which dominates flow at scale of pumping tests. These two main aspects are taken into account by combining generalized radial flow with fractional dimensions, with double-porosity theory, including diffusion in the second porosity, transient inter-porosity exchange and inter-porosity skin effect, or with drainance. Implementation of this nD model, with fractional n, usefully extends field of application of usual 1D/2D/3D double-porosity or drainance models, to a wide range of fracture network connection levels. Although fracture geometry and properties are not taken into account one by one or by directional families, they are accounted for by average properties and by impact that overall network has on hydrodynamic behavior. Accuracy of coupled transient behavior analysis is enhanced by taking into account skin and well capacity effects. Multi-stage pumping tests are modeled using superposition principle. Use of these different options enables reconstruction of a wide range of pumping test curves, characteristic of various media, with a limited number of parameters.