ABSTRACT
A large-slot flow apparatus for investigating hydraulic fracturing fluid flow and proppant transport phenomena has been jointly developed by the Gas Research Institute (GRI), the Department of Energy (DOE), and The University of Oklahoma. A series of tests were performed to confirm the operational readiness of this apparatus to perform the many functions for which it was designed. This paper describes results obtained from the verification tests, particularly in terms of the proper functioning of instrumentation and control systems under a wide range of operating conditions. Tests performed were: flow of crosslinked gels, high-temperature (200 and 225pF) flow tests, high-pressure (1,000 psi) flow tests to confirm proper operation of a unique throttling valve, effect of pressure on perforation pressure loss, and dynamic fluid-loss tests with permeable facings at 1,000 psi.
Verification tests listed above were performed and the large-scale, high-pressure, fracture-flow simulator was found to be fully functional in nearly every respect. Functionality was established by comparing flow data from the simulator to conventional viscometric results whenever possible. Some surprises, in terms of both flow cell response and fluid behavior, were found during the course of verification testing. For example, there was the discovery that crosslinked gels exhibit a slip-like flow phenomenon in the simulator. This latter phenomenon was discovered while using the variable width capability of the apparatus. A methodology was developed which allows collection of meaningful flow data in the presence of this slip-like phenomenon. An additional surprise was the discovery that there was no effect of elevated pressure on the perforation pressure loss, as some industry critics have suggested.
