Publication Date:
2012-05-01
Description:
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 (0.021±0.002/°C). 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 m and n. We found m=1.56±0.04 for the cementation exponent while the saturation exponent is given by n=1.93±0.07 when the sand is oil-wet and n=1.65±0.07 when the rock is water-wet. The power-law exponent for the quadrature conductivity of the water-wet samples is p=1.18±0.58.
Print ISSN:
0016-8033
Electronic ISSN:
1942-2156
Topics:
Geosciences
,
Physics
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