Reservoir detection

Hydrocarbon reservoir detection by interpretation of microtremor wavefields on large arrays

(PhD Stefano Maranò)

Hydrocarbon-bearing geological structures might cause characteristic modifications of the ambient vibration background noise. This question is adressed in a project supported by the Commission for Technology and Innovation (CTI) together with the company SpectraSeis. The link between observations and geological structure can only be made by understanding the wavefield that is recorded. This requires the simultaneous recording and analysis of ambient vibration wave-fields on arrays. Such methods have been developed in the past, and they have been applied to study soft-sediment surface deposits for seismic hazard analysis.

The analysis of all three components of ground motion is addressed. Analysis of such recordings targets to distinguish between standing waves (global resonances) and propagating surface waves (Love- and Rayleigh-waves) as well as body waves (SH and PSV). By adapting array configurations during the measurements in the field, the identification of the wave-types with the corresponding propagation velocity and direction is optimized and allows to determine the source region of the waves and their possible origin. From the wave characteristics, structural information can be inverted that allows to improve structural models. The development of a real-time system for array measurements is part of the project.

Measurement overview of a large array in the St. Galler Rheintal, recording signals from active sources used for seismic exploration. The yellow lines correspond approximately to the path covered by vibroseis trucks.

LINK TO PARTNERS

Spectraseis AG - http://www.spectraseis.com

Signal and Information Processing Laboratory, ETH Zurich - http://www.isi.ee.ethz.ch