Rock Deformation and Fluid Transport
Our laboratory currently houses several mechanical and transport systems, dedicated to test natural rocks samples at in-situ conditions. We aim to identify the mechanisms that control bulk rock deformation, and how this relates to larger scale fault movement and fluid transport. Our scale of focus therefore varies from the crustal scale to the reservoir scale. At the moment, we mainly test unconventional reservoir rocks such as shales and coal.
The following people in the Zoback Stress and Crustal Mechanics Group regularly work in the lab: Maytham Al Ismail, Yves Gensterblum, Arjun Kohli (Lab Manager), Xiadong Ma, Fatemeh Rassouli (Safety manager) and Wei Wu. The work in our own mechanical and transport lab is combined with high resolution image analysis performed at the Stanford Nanocharacterization Lab, but also at other locations. Very frequently our lab results support reservoir geomechanics interpretations made by others in the Zoback group.
GCTS RTR-1000 | Triaxial system capable of rock deformation experiments up to confining and pore pressures up to 140 MPa (20000 psi), with a maximum axial load of 1000 kN. The cell accepts samples with a diameter of up to 75 mm (3 inch) with a length of two times the diameter, and can hold different types of sensors including internal load cells, LVDT’s, and ultrasonic transducers. A heating system enables experiments up to 150 °C. At the moment, we use the machine to assess frictional properties of shales (AK), as well as to understand the formation of compaction bands in pure sand (ES).
NER Autolab 2000 | Recently upgraded, triaxial system capable of testing under confining pressures up to 200 MPa (29000 psi). Since we test mainly using gases as pore fluids, we use a separate Quizix pump to generate He, CO2, CH4, and N2 pore pressures up to 10 MPa (1500 psi). The NER cell accepts either one- or two-inch core samples and holds an internal load cell, LVDT’s, and an ultrasonic transducer. All experiments in this system run under room temperature. We use this system to investigate mechanisms of time-dependent deformation of shales (SH and YY).
Thermally-controlled permeability system | Set-up consisting of a Temco core holder, coupled to a Quizix pump and a manually operated confining pressure cylinder. All components are enclosed in a sealed polystyrene box, which is thermally controlled by two heaters and a powerful fan. We are capable of running experiments with the following maximum testing conditions: 41 MPa (6000 psi) confining pressure, 34 MPa (5000 psi) fluid pressure and a constant temperature of 40 °C. We use this system to assess the mechanisms of fluid transport in gas shales (RH and SH).
Manometric adsorption system | Various pressure cells submerged in a temperature bath, and coupled with an Argilent MicroGC to determine chemical composition of gas mixtures. The system is used to determine CO2, Kr, CH4, and N2 sorption of gas shales (RH).
Sone, H and M.D. Zoback, Mechanical properties of shale-gas reservoir rocks — Part 1: Static and dynamic elastic properties and anisotropy, Geophysics, v. 78, no. 5 (September-Octorber 2013), D381-D392.
Sone, H and M.D. Zoback, Mechanical properties of shale-gas reservoir rocks — Part 2: Ductile creep, brittle strength, and their relation to the elastic modulus, Geophysics, v. 78, no. 5 (September-October 2013), D393–D402.
Kohli, A.H. and M.D. Zoback, Frictional properties of shale reservoir rocks, J. Geophys. Res. Solid Earth, v. 118, 1–17, 17 August, 2013. doi:10.1002/jgrb.50346, 2013
Yang, Y. and Zoback, M.D., The Effects of Gas Adsorption on Swelling, Visco-plastic Creep and Permeability of Sub-bituminous Coal, ARMA 11-433, in 45th US Rock Mechanics / Geomechanics Symposium held in San Francisco, CA, June 26-29, 2011.
Sone, H., Zoback, M.D, Visco-plastic Properties of Shale Gas Reservoir Rocks, ARMA, 11-433, in 5th U.S. Rock Mechanics / Geomechanics Symposium, San Francisco, California, June 26 - 29, 2011.
*Chang, C. and M.D. Zoback, Viscous creep in room-dried unconsolidated Gulf of Mexico shale (II): Development of a viscoplasticity model, Journal of Petroleum Science and Engineering, v.72, 50-55.
Sone, H. and M.D. Zoback, Strength, creep and frictional properties of gas shale reservoir rocks, paper presented at 44th US Rock Mechanics Symposium and 5th US-Canada Rock Mechanics Symposium, Salt Lake City, Utah, June 27-30, 2010, paper ARMA 10-463.
Hagin, P.N. and M.D. Zoback, Inverting for creep strain parameters of uncemented reservoir sands using arbitrary stress-strain data, paper presented at 44th US Rock Mechanics Symposium and 5th US-Canada Rock Mechanics Symposium, Salt Lake City, Utah, June 27-30, 2010, paper ARMA 10-171.
*Chang, C. and M.D. Zoback, Viscous creep in room-dried unconsolidated Gulf of Mexico shale (I): Experimental results, Journal of Petroleum Science and Engineering, v. 69, 239-246
*Hagin, P., Sleep, N.H. and M.D. Zoback, Application of rate-and-state friction laws to creep compaction of unconsolidated sand under hydrostatic loading conditions, Jour. Geophys. Res., 112, DOI:10.1029/2006JB004286.
*Hagin, P. and M.D. Zoback, A dual power law model for prediction and monitoring of long-term compaction in unconsolidated reservoir sands, Geophysics,72(5),E165-E173.