A New Compositional Model for Hydraulic Fracturing With Energized Fluids

Traditional fracturing models regard fracturing fluids as a single-component, single-phase fluid. This assumption is clearly incorrect for energized fluids where phase changes and mass transfer between phases play important roles in controlling fluid rheology, leakoff, and fracture geometry. A model is developed to simulate hydraulic fracturing with energized fluids. Compositional balances allow tracking of the changes in phase behavior and fluid properties. Such as rheology and multiphase leakoff. An energy balance is implemented in order to consider temperature changes during fracturing. Phase behavior has been taken into account through an equation-of-state (EOS) formulation. These compositional- and phase-behavior effects are coupled with a geomechanical model for fracture propagation. It is shown that phase behavior and leakoff can change the composition and fluid rheology in the fracture significantly. This has a dramatic effect on the fracture geometry. Phase-behavior changes are coupled closely to the temperature and pressure changes in the fracture. The temperature, phase behavior, and partitioning of components in the liquid and gas phases have a significant effect off fracture dimensions. For example, shorter and wider fractures can be obtained by foaming an energized fluid. With the model presented, these temperature, pressure, and composition changes can now be modeled accurately and incorporated into the fracture growth and geometry.