Applications V(P)/V(S) and AVO modeling for monitoring heavy oil cold production

Simultaneous extraction of oil and sand during the heavy oil cold production generates high porosity channels termed "wormholes". The development of wormholes causes reservoir pressure to fall below the bubble point, resulting in dissolved-gas coming out of solution to form foamy oil. Both foamy oil and wormholes are believed to be two key factors in the enhancement of cold heavy oil production. In enhanced oil recovery, it is important to map cold production reservoir changes due to wormholes and foamy oil. It is the purpose of this thesis to use seismic monitoring methods to map cold production footprints.; The presence of small amounts of gas trapped in the foamy oil can dramatically decrease the fluid bulk modulus, reducing the P-wave velocity of saturated sands, while slightly increasing the S-wave velocity. The Vp /Vs ratio and Poisson's ratio have a subsequent reduction.; The viscosity of heavy oil is primarily a function of oil gravity and temperature. Increasing the temperature will decrease sample's viscosity, causing both bulk and shear moduli to decrease approximately linearly with increasing temperature. Moreover, the frequency also plays an important role for seismic waves in heavy oil. For heavy oil in the 10-20 API range at ambient temperature of 20°C, the shear modulus is negligible and heavy oil still acts like a liquid at seismic frequencies, especially after cold production. Gassmann's equation can still help us understand the seismic response of heavy oil reservoirs for pre- and post-cold production.; The Vp/Vs ratio is a function of both fluid bulk modulus and porosity. For unconsolidated sands with high porosity, pore fluids have a significant influence on final V p/Vs ratio. Due to the dramatic reduction of fluid's bulk modulus after heavy oil cold production, the Vp/V s ratio will have a detectable reduction, even though the increasing porosity from wormholes slightly increases the Vp/V s ratio. For unconsolidated sands, the lower pore pressure and increasing differential pressure will also tend to decrease the final Vp/Vs ratio. (Abstract shortened by UMI.)...