Abstract

Up to now, only one study has provided a global model for the fracture calibration test, but this model included only normal closure with homogenous reservoir behavior after closure. Recent work has revealed new models for abnormal before-closure leakoff behaviors. This study combines normal and abnormal leakoff behaviors with a more general after-closure reservoir model that incorporates a wellbore storage analog and dual-porosity heterogeneity.

The new global model will mimic the previously successful strategy using splines to connect fully general before- and after-closure behaviors.

The resulting model permits highly insightful sensitivity studies addressing plausible combinations of abnormal leakoff behaviors and likely after-closure features. For instance, parameters that can be quantitatively determined include flow friction, fracture dimensions, leakoff coefficient, natural fracture properties, fracture closure pressure, and permeability, formation pressure, etc. Field data will be matched before and after closure using the new global model.

Matches with field data reflect highly enhanced understanding of the nature of hydraulic fracturing and naturally fractured flow mechanisms that have not been possible up to now and that greatly refine well design strategies. Compared with the traditional piecewise before- and after-closure analysis, many more parameters can be quantified from the complete global fracture model, and it provides more insight on the main fracturing design and post-treatment production estimation. The global history match ensures consistence and validity of the model well beyond what can be achieved with isolated before- or after-closure analysis.

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