Mid-Continent Section

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Frictional properties of reservoir rocks during high-velocity slip


Micro-seismic events have been a known byproduct of hydraulic fracturing and oil/gas production. Knowing the frictional properties of reservoir rocks during dynamic seismic events is essential for understanding and controlling the induced seismicity. My MS research project is collaboration between the University of Oklahoma and ConocoPhillips to determine reservoirs frictional properties at earthquake conditions. The project focuses on testing rock samples from five different formations within three separate reservoirs. Core fragments from these reservoirs were fragmented into sand-size grains, and then sheared in a Confined ROtary Cell (CROC) as dry or water- saturated granular material. Shearing is conducted at slip velocity and slip-distance similar to natural earthquakes, namely slip-velocity of 0.005 m/s to 0.6 m/s and distances of 1.25 m to 7 m. We conducted about 70 initial experiments and the preliminary results show that the friction coefficient range widely from very low (∼ 0.1) to very high (∼1.2) with strong dependence on the main mineralogical groups (calcite, quartz, clay). Future work will be devoted to: (1) investigation of the dynamic friction dependence on the slip-velocity, in particular the characterization of velocity-weakening and/or velocity-strengthening, (2) correlation between friction and sample mineralogy and (3) apply the experimental results to seismicity characteristics during hydro-fracturing.