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DSSS: Hydraulic Fracturing: Theory – Reality – Uncertainty

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More Information:  Maurice Dusseault is a Professor of Geological Engineering, Earth and Environmental Sciences Department, University of Waterloo, teaching rock mechanics and oil production methods.  He carries out research in geomechanics in mining and oil and gas development, oil production technologies, and deep waste disposal technologies using hydrofracturing.  Current interests include CO2 sequestration, hydraulic fracturing, biosolids injection, leaky wells, and thermo-hydraulic-mechanical coupling issues.  He has co-authored two textbooks with John Franklin (former International Society for Rock Mechanics President) and 500 full text articles.  He works widely with industry and governments as an advisor and professional instructor and was a Society of Petroleum Engineers Distinguished Lecturer in 2002-2003, visiting 19 countries and 28 separate SPE sections.  The Petroleum Geomechanics Commission of the International Society for Rock Mechanics was formed in October 2011, and his involvement as its president is intended to develop this area of rock mechanics.

Abstract:  Hydraulic fracturing (HF) has emerged as an important enabling technique in development of shale oil and shale gas, geothermal energy exploitation, and slurried solids disposal at depth.  For example, the City of Los Angeles is injecting biosolids sludge on a trial basis into a depleted reservoir 1350 m deep under HF conditions as a means of treatment, with potential for harvesting generated methane.

The challenge facing the geomechanics community is development of a deep understanding and analysis methods for HF in naturally fractured (jointed) rock masses such as igneous rocks, petroliferous carbonates, and shale oil and shale gas reservoirs.  Scale is critical: at the tip, local fabric dominates propagation; when fracture length is large, global propagation is dominated by the large-scale principal compressive stresses.  Fluid density, viscosity and injection rate affect propagation, and in many cases, induced displacements can change the local principal stress values and lead to secondary fracture arms, an important factor in developing fracture networks.

Maurice will discuss what we can and cannot yet do in HF simulation and design.  Changes of direction, stress alterations, buoyancy effects, and stress field variations in situ will be discussed.  There are no easy answers, the goal of the talk will be to cast some clarity on the physical mechanisms involved in hydraulic fracturing in rock masses with strong fabric, and see what options are available for engineers to pursue in design and implementation of HF technologies.