Abstract
We investigate how combined use of time-lapse PP and PS seismic stacks
can be utilized for discrimination between pressure and saturation
changes. The theory is based on a combination of the well-known Gassmann
and Hertz-Mindlin models. To simulate the amplitudes on PP and PS
sections we compute the stacked reflection coefficients within a
given angular span. Cross-plotting the PP and PS amplitude changes
against the pressure and saturation changes, enables simultaneous
estimation of pressure and saturation changes. The method is tested
on a realistic 2D finite-difference time-lapse seismic dataset from
the Gullfaks Field. The uncertainties in the estimated saturation
and pressure changes are expressed by the uncertainties in PP and
PS stack amplitudes. We find that this method is strongly dependent
on the in situ stress conditions, and especially that low values
for the initial effective pressure mean low discrimination sensitivity.
Users
Please
log in to take part in the discussion (add own reviews or comments).