  In thermally enhanced recovery processes like cyclic steam stimulation (CSS)
or steam assisted gravity drainage (SAGD), continuous steam injection entails
changes in pore fluid, pore pressure and temperature in the rock reservoir,
that are most often unconsolidated or weakly consolidated sandstones. This in
turn increases or decreases the effective stresses and changes the elastic
properties of the rocks. Thermally enhanced recovery processes give rise to
complex couplings. Numerical simulations have been carried out on a case study
so as to provide an estimation of the evolution of pressure, temperature, pore
fluid saturation, stress and strain in any zone located around the injector and
producer wells. The approach of Ciz and Shapiro (2007) - an extension of the
poroelastic theory of Biot-Gassmann applied to rock filled elastic material -
has been used to model the velocity dispersion in the oil sand mass under
different conditions of temperature and stress. A good agreement has been found
between these predictions and some laboratory velocity measurements carried out
on samples of Canadian oil sand. Results appear to be useful to better
interpret 4D seismic data in order to locate the steam chamber.

Geophysics