The Friction Measuring Tool: Real-Time Estimates of Sandface Pressure During Fracture Treatments

This paper describes a Friction Measuring Tool (FMT) and how it is used to estimate pressure loss from friction in the wellbore while a foam fracture treatment is being pumped. Combined with standard surface equipment, such as densitometers, flowmeters, and pressure transducers, this tool (located on the surface) offers real-time estimates of bottomhole treating pressures during the fracture treatment. Field examples are presented comparing calculated bottomhole treating pressures, based on the FMT, to actual pressures measured with downhole electronic pressure gauges (installed in the casing just below the treated zone) during stimulation treatments. In addition to the provided field examples which verify application of the FMT, the theory and mathematical background underlying the use of the FMT are described. Construction of the tool, actual use in the field, and trouble-shooting are also presented. This tool is also applicable to foam for coiled tubing operations or stable foam drilling. Development of the FMT is one product of a cooperative research program sponsored by the Gas Research Institute (GRI) where one of the broad research objectives is improved stimulation techniques.