Passive seismic study at an oil and gas field in Voitsdorf, Austria
Published in
Workshop on Passive Seismic Limassol, Cyprus
Date of publication
22 March 2009
Abstract
Low-frequency (< 10 Hz) spectral anomalies observed in the ambient seismic wave field at the Earth’ surface have recently been used as hydrocarbon (HC) indicators (Dangel et al. 2003; Graf et al. 2007, and references therein). The main observation is an energy anomaly in the low frequency band of passive seismic data approximately between 1 and 6 Hz. At the surface, above the reservoir, spectral energy is elevated compared to positions off the reservoir. Most of these empirical observations are based on the vertical component of ground motion only. However, Saenger et al. (2007) and Lambert et al. (2008) have introduced vertical-to-horizontal spectral ratios (V/H-ratios) for the same purpose. Spectral ratios are especially useful because they are more stable than single component, or absolute, spectra (Bard 1999, and references therein). Motivated by these observations, a passive seismic survey has been carried out over an explored oil and gas field near Voitsdorf, Austria. We use this field as a test site to investigate correlations between anomalies of four different spectral attributes and the HC reservoir locations. We compare the results of a survey done in April 2007 with preliminary results of a survey done in April 2008 in order to test the results for consistency and reproducibility.
