Abstract
The primary purpose of hydraulic fracturing is to provide highly conductive paths from the reservoir to the wellbore. This is accomplished by pumping fracturing fluids at extreme pressures to create fractures in the reservoir rock. In addition to creating the fractures, the fluid is used to carry proppant into the fractures to keep them open for flow after the pressure is relieved.
The performance of fracturing fluids is generally determined by their ability to 1) create fracture width and length with minimal loss of energy caused by friction, 2) efficiently transport proppant through the tubulars and deep into the fracture, 3) keep the proppant suspended to help distribute proppant vertically in the fracture, 4) break on a planned schedule to permit rapid and efficient flowback without producing back the proppant, and 5) perform all of these goals economically.
There are several good methods available to determine fluid efficiencies, proppant transport properties, and fluid break times that are important to a stimulation engineer when designing fracture treatments. However, there are few methods available that adequately simulate post-fracturing fluid recovery that provides the expected well cleanup rate, efficiency, and impairment of proppant pack conductivity.
This paper presents the development of a laboratory method that permits the determination of post-fracture cleanup parameters of a fluid system under realistic reservoir conditions. Fluid rheology and fluid recovery data are presented that compare commonly used fracturing fluid systems with a variety of breakers and proppant types. The use of this data should aid stimulation engineers in the selection of the optimum fluid system, breaker package, and proppant combination for specific reservoir conditions.
