A plot of excess pressure vs. time can be used to predict fracture-growth patterns only when both the viscosity of the fluid in the fracture and the stress at the fracture tip remain constant. This paper uses laboratory data and field examples to explain how increased friction owing to viscous slurries affects the interpretation of fracturing pressures.

Keywords:
viscosity, excess pressure, friction pressure, fluid viscosity, concentration, fracturing materials, proppant, high proppant concentration, upstream oil & gas, slurry viscosity
Subjects:
Fracturing materials (fluids, proppant), Hydraulic Fracturing, Reservoir Characterization, Reservoir geomechanics
Copyright 1991, Society of Petroleum Engineers
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