A New 3D Compositional Model for Hydraulic Fracturing With Energized Fluids

摘要

While several 3D fracturing models exist for incompressible water-based fluids, none are able to capture the thermal and compositional effects that are important when using energized fluids such as CO_2, N_2, LPG, and foams. This paper introduces a new 3D, compositional, non-isothermal fracturing model. The new model predicts changes in temperature and fluid density. These changes are treated on a firm theoretical basis by using an energy-balance equation and an equation of state, both in the fracture and in the wellbore. The model is capable of handling any multicom-ponent mixture of fluids and chemicals. Changes in phase behavior with temperature, pressure, and composition can be modeled. A new simulator has been developed based on the compositional model presented in this paper. The simulator is validated for traditional fluid formulations against known analytical solutions and against a well-established commercial fracturing simulator. Results from the new simulator are then presented for energized fluids such as CO_2 and LPG. In particular, the compositional model shows how fluid expansion and viscosity reduction impact fracture growth. These effects are not captured by traditional fracturing simulators. The compositional tool is specifically suited for fracture design in formations in which energized fluids constitute a viable alternative to traditional fracturing fluids.