Energy and Environment

High permeability pathways triggered by subsurface storage operations

Raess, L. , Yarushina, V.M. , Simon, N.S.C. , Podladchikov, Y.Y.
Second EAGE Workshop on Geomechanics and Energy, Celle (Germany), 2015-10-13--10-15
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High permeability fluid flow pathways are widely observed in nature, and their formation occurs on both geological and human timescales. Outcrop study as well as interpretation of seismic cross-section show clear evidences of these multi-scale vertical pipe features, where unconsolidated to loose material is present inside. Even if well documented, their formation process remains still not answered yet. We propose a physically consistent 3D two-phase model of focusing fluid flow that allow the formation of such vertical high permeability channels. Viscous or creep rheology is the key feature to explain this formation process. Our result show that the proposed mechanism triggers pipe formation where permeability increases over two orders of magnitude in impermeable shale, and with propagation speed close to 2 meters per year in these usual ceiling rocks. Our results are in good accordance with the values needed to explain the fast vertical breakthrough of CO2 plume in the layered Sleipner saline aquifer.
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