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Fluid Injection Induced Rock Failure Under True Tri-Axial Stress Condition

April 24, 2020 @ 2:00 pm - 3:00 pm

Zhou, Xue Jun (John), Research Associate, Mewbourne School of Petroleum & Geological Engineering of
the University of Oklahoma, Norman

What to Expect

After a short overview of the different types of laboratory tests that Dr. Zhou has conducted in the rock mechanic laboratory at the University of Oklahoma, the focus will be given to the tests of fluid injection induced rock (granite and schist) failures under true tri-axial stress condition. These tests revealed that fluid injection induced fractures are always opened against the direction of the minimum principal stress and sub-parallel with respect to the maximum principal stress. For a relatively homogenous and intact sample, a totally new fracture is initiated from the spot of the stress concentration, and a higher injection fluid pressure might be needed to open such fracture. The process is violent as demonstrated by a large number of AE events, and the opened fracture can create a larger void space instantaneously. The shear angle of the fracture is governed by the intrinsic rock property and satisfy the correlation with the internal friction angle. For a heterogeneous sample with embedded foreign matters (such as quartz vein), the interface between different materials usually present a weak zone, and thus, a relatively lower fluid injection pressure can cause the coalescence of these weak spots to form a new fracture. This process seems to be much less violent as evidenced by much less acoustic events. The orientation and location of the fracture are impacted by the distribution of these weak spots, and the created shear angle is different from what is expected for a homogeneous sample.

Speaker Bio

Zhou, Xue Jun (John) is a research associate working in the rock mechanic lab with Prof. Ghassemi in the Mewbourne School of Petroleum & Geological Engineering of the University of Oklahoma (2014-present). He has lab experience for different tests on different types of rocks, including poro-elastic tests, AE characterization of fluid injection induced failure under true triaxial condition, creep of shale and rock salt under high temperature, brittleness evaluation by recording Class I and Class II failure, etc. He had been a postdoc at Virginia Tech’s Geosciences Department for 3 years before OU. Working with Prof. Burbey, a hydrogeologist, his research was focused on the three-dimensional deformation of ground and earthquake due to fluid injection in deep formations. He got his PhD (Geological engineering) from the Harold Hamm School of Geology & Geological Engineering of the University of North Dakota (UND). Working with his advisor Dr. Zeng Zhengwen and other students, a novel rock mechanic testing facility was developed to conduct CO2 sequestration related tests. He has a Master’s degree in Mining from Montana Tech, a diploma in mining from British Columbia Institute of Technology (BCIT) of Canada and a bachelor degree (Information Engineering) from XiDian University of China.


Tim Kneafsey