Recent work provided a model for the fracture calibration test in a homogeneous reservoir and an interpretation methodology that enables determination of the formation permeability. The previous study used a rate-dependent skin for the filtercake resistance. Pressure drop in the formation was modeled using a closed form solution for linear flow. The need to analyze tests conducted in naturally fractured reservoirs has motivated the work in this paper.
To model dual-porosity reservoir heterogeneity, the linear flow closed form solution was replaced by an analytical solution. The heterogeneous model uses a standard pressure transient model formulation while incorporating the filtercake resistance from the previous work.
Analysis of data from fracture calibration tests in naturally fractured reservoirs shows that the homogeneous model fails to capture transient behavior attributed to natural fractures. Sensitivity studies using the new model illustrate the pressure falloff response behavior and show what can be determined from the failoff analysis.