Abstract: We conducted a geomechanical case study to investigate the variations of in-situ stress and formation properties along two horizontal wells in the Woodford shale (WDFD), Oklahoma. The minimum horizontal stress (Shmin) indicated by the Instantaneous Shut-In Pressure (ISIP) of each frac stage, varies dramatically from stage to stage along both WDFD wells，which correlates well with the clay content. Variations of Shmin with lithology in these litho-facies can be plausibly explained by the viscous stress relaxation, which results in the diminishing difference between Sv and Shmin as the compliant component content increases. Prediction of Shmin through a viscoelastic model is in qualitative agreement with the measured ISIP values.
Biography: Dr. Xiaodong Ma is an Oberassistent (senior scientist) and lecturer at ETH Zürich. He is affiliated with the Swiss Competence Center for Energy Research – Supply of Electricity (SCCER-SoE) and the Department of Earth Sciences. His research interest lies in crustal stress, reservoir geomechanics, geothermal energy, and experimental rock mechanics. He is currently leading the geomechanics efforts of the Bedretto Underground Laboratory (BUL) for field experiments related to enhanced geothermal systems and induced seismicity.
Dr. Ma obtained his PhD degree in geological engineering (2014) from University of Wisconsin-Madison, and subsequently conducted post-Doctoral research at the Stress and Crustal Mechanics Group, Stanford University before joining ETH Zürich in 2017. He had previously tackled on a variety of geomechanical challenges, including the experimental characterization of the true triaxial mechanical response of porous sandstones, poroelastic behavior of unconventional reservoir rocks, and stress variation in shales and its effect on the effectiveness of hydraulic fracturing.
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