Natural Gas Storage Seismic Monitoring
Résumé
IFP Energies nouvelles, CGGVeritas and GDF Suez have conducted together, since 1980, a
series of seismic monitoring experiments in order to detect and follow the movements of
the gas plume in natural gas geologic storages. Surface and well seismic surveys were
carried out at different stages of the storage life. Permanent receiver arrays have been
set down in wells. Permanent sources have been designed. Sources and receivers have been
used to follow continuously the storage cycle during several years, providing time
measurement accuracy within a tenth of a millisecond. Gas intrusion into an aquifer leads to an increase in the arrival times of reflections
beneath the storage reservoir and to a variation of the reflection amplitudes at top and
bottom of the reservoirs. Progressive variations of the seismic parameters may be followed during the initial
infill period. Further movements of the gas plume with the annual in/out cycles are more
difficult to follow, because of the simultaneous presence of gas and water in the pores.
Arrival time variations of some tenths of a millisecond may be detected and measured.
Saturations, using accurate picking of the arrival times, can be estimated in favourable
cases. Because of the higher density of carbon dioxide, when stored in a supercritical phase,
sensitivity of the seismic parameters, velocity, density and acoustic impedance to
saturation variations will be about twice smaller for CO2 storages than it is
for methane.
Domaines
Physique [physics]
Origine : Publication financée par une institution
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