Past viscoelastic surfactant (VES) gelled fluids used for fracpacking and conventional hydraulic fracturing have primarily relied on external or reservoir conditions to break (reduce) the fluids gel viscosity. This paper describes an internal phase breaker system developed for breaking viscoelastic surfactant gelled fluids. Laboratory rheological data is presented that shows controlled viscosity reduction can be achieved from 80°F to 225°F by the use of two or three aqueous breaker solutions. The mix waters evaluated were KCl, CaCl2, and ASTM synthetic seawater. The results show that break times typical for polymeric fluids can now be achieved for VES gelled fluids.

Keywords:
fluid modeling, concentration, proppant, ve gel break test, fracturing fluid, fluid system, ve gelled fluid, gptg 0, hydraulic fracturing, break test
Subjects:
Drilling Fluids and Materials, Hydraulic Fracturing, Fluid Characterization, Drilling fluid management & disposal, Frac and pack, Fracturing materials (fluids, proppant), Fluid modeling, equations of state, Sand Control, Completion Operations
Copyright 2005, Society of Petroleum Engineers
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