ABSTRACT
The joint inversion of seismic and electromagnetic data can be of great use to monitor the steam-assisted production of heavy oils in field conditions. Seismic velocity and complex conductivity laboratory measurements were performed on three heavy oil-bearing sands at confining and pore pressures similar to field conditions. One of the samples (8H) was initially oil-wet and the two other samples (5P-3A and P-1A) were initially water-wet. Low-frequency stress-strain measurements and complex conductivity measurements were performed during two heating cycles (at constant temperature, 10°C steps in the range 20°C–70°C). The temperature was first increased from 20°C–70°C simulating initial stage in a thermal recovery process. During this temperature increase, sample 8H changed to water-wet with a clear irreversible signature on the seismic and electrical data. Then the temperature was decreased and cycled a second time in the temperature range 20°C–70°C. The seismic and complex conductivity responses were found to be identical at each temperature for the temperature decrease of the first heating cycle and the second cycle. For the water-wet samples (5P-3A and P-1A), the compressional and shear velocities decreased with the increase of temperature and the in-phase and quadrature conductivities increased with the temperature with the same temperature sensitivity coefficient (). After these two heating cycles, we extracted the heavy oil from sample 8H and additional complex conductivity measurements were performed at different salinities to determine the two Archie’s exponents and . We found for the cementation exponent while the saturation exponent is given by when the sand is oil-wet and when the rock is water-wet. The power-law exponent for the quadrature conductivity of the water-wet samples is .