Numerical Modeling of Hydraulic Fracturing in Oil Sands

Hydraulic fracturing is a widely used and ecient technique for enhancing oil extraction from
heavy oil sands deposits. Application of this technique has been extended from cemented rocks
to uncemented materials, such as oil sands. Models, which have originally been developed
for analyzing hydraulic fracturing in rocks, are in general not satisfactory for oil sands. This
is due to a high leak-o in oil sands, which causes the mechanism of hydraulic fracturing to
be dierent from that for rocks. A thermal hydro-mechanical fracture nite element model is
developed, which is able to simulate hydraulic fracturing under isothermal and non-isothermal
conditions. Plane strain or axisymmetric hydraulic fracture problems can be simulated by this
model and various boundary conditions, such as specied pore pressure/
uid
ux, specied
temperature/heat
ux, and specied loads/traction, can be modeled. The developed model has
been veried by comparing its results to existing analytical and numerical solutions for thermoelastic
consolidation problems. The model has been used to simulate a laboratory experiment
of hydraulic fracture propagation in oil sands. The results from the numerical model are in
agreement with experimental observations. The numerical model and laboratory experiments
both indicate that, for uncemented porous materials, such as sands (as opposed to rocks), a
single planar fracture is unlikely to occur and a system of multiple fractures or a fracture zone
consisting of interconnected tiny cracks should be expected.