Details of the acquisition design, processing, deterministic inversion via several methods and final interpretation are discussed in McCrank and Lawton (2009) and McCrank (2008). IntroductionĪ 3D vertical component seismic survey was conducted at the Alder Flats location in June 2007. The modelling shows that the effect of short-path multiple reflections, built up in the seismic pulse from the stacked coal sub-zones, could cause a phase delay in the reflected energy of the deepest coals and which would explain the results of the inversion. This phenomena is possibly explained by the results of synthetic modelling that investigates the effects of short-path multiple reflections.
However, while the inversion appears to be accurate at the level of the shallow-most coals, at the deeper coal subzones a thin but significant sub-zone is not detected in the inversion, even when the inversion is constrained by the well data. As well, the multiple model realizations provide a range of acoustic impedance and net coal-thickness estimates that can be used to quantify uncertainty in the results. The mean of the realizations gives a highly resolved estimate of the acoustic impedance. The inversion provides multiple model realizations each of which honors the seismic data, the well data and the geostatistics. A geostatistical inversion is conducted in an attempt to improve the inversion resolution and assess model uncertainty. Additionally, the thin sub-zones of the Ardley Coals are not differentiated in the inversion. Deterministic inversion of the data shows a band-limited acoustic impedance result that over estimates the very low impedance of the coals as well as overestimating the thickness of the coal zones.
A 3D seismic data set was acquired near Alder Flats, Alberta, to image several coal zones of the Ardley Coals.
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