3-D Local Radon Power Spectra for Seismic Attribute Extraction

Conference paperIn this paper we discuss a method for volume attribute extraction that is based on a new type of local Radon power spectrum. The new algorithm results in robust and geologically meaningful volume attributes, such as volume dip and azimuth. Seismic volume attribute analysis greatly facilitates the interpretation of large 3-D seismic data volumes. However, horizon attribute maps are generally more easy to interpret than volume attribute images, which are usually time slices or cross-sections. We show that, for dip estimation, the volume attribute image is very similar to the horizon dip map

3-D Local Radon power Spectra for seismic Attribute Extraction

In this paper we discuss a method for volume attribute extraction that is based on a new type of local Radon power spectrum. The new algorithm results in robust and geologically meaningful volume attributes, such as volume dip and azimuth. Seismic volume attribute analysis greatly facilitates the interpretation of large 3-D seismic data volumes. However, horizon attribute maps are generally more easy to interpret than volume attribute images, which are usually time slices or crosssections. We show that, for dip estimation, the volume attribute image is very similar to the horizon dip map

Decomposition of seismic signals via time-frequency representations

Conference PaperIn this paper we discuss the use of a time-frequency representation, the Wigner distribution, for the decomposition and characterization of seismic signals. The advantage of the Wigner distribution over other representations, such as the wavelet and sliding window Fourier transform, is its sharp localization properties in the time-frequency plane. However, the Wigner distribution is a not a linear transformation. This non-linearity complicates the use of the Wigner distribution for time-frequency filtering and decomposition. We present an optimization method for the reconstruction of a time signal from its Wigner distribution. The reconstruction technique enables a decomposition of a signal into its time-frequency components, where the reconstructed components are stripped off from the signal one by one. The method is illustrated a real data example. We also demonstrate how the decomposition can be used for suppression and enhancement of events in the time-frequency plane

Scaling propagation phenomena as result of an externally applied isotropic stress on an aeolian Rotliegend sandstone sample.

Introduction As stated by Dake (1978) the overburden pressure in a reservoir can be equated to the sum of the fluid pressure and the grain or effective pressure. From this it follows that a decrease of fluid pressure during production can be directly related to an increase of formation pressure. In our experimental study we relate stress, in the 0-82 MPa region, to full ultrasonic wave forms. We do this to gain insight in the possibility to monitor stress in reservoirs, using time-lapse seismics. This technique measures differences in seismic response, as a result of production. We perform experiments on aeolian Rotliegend sandstone with comparable characteristics as the reservoir rock of the Dutch gas fields. Sample specification The test material used is an aeolian Upper Rotliegend sandstone, outcrop material quarried near Magdeburg in Germany. This sample rock was chosen because the reservoir quality is comparable to the Rotliegend sandstone of e.g. the Du

Decomposition of seismic signals via time-frequency representations

In this paper we discuss the use of a time-frequency representation, the Wigner distribution, for the decomposition and characterization of seismic signals. The advantage of the Wigner distribution over other representations, such as the wavelet and sliding window Fourier transform, is its sharp localization properties in the time-frequency plane. However, the Wigner distribution is a not a linear transformation. This non-linearity complicates the use of the Wigner distribution for time-frequency ltering and decomposition. We present an optimization method for the reconstruction of a time signal from its Wigner distribution. The reconstruction technique enables a decomposition of a signal into its time-frequency components, where the reconstructed components are stripped o from the signal one by one. We illustrate the method with a real data example. We also show how the decomposition can be used for suppression and enhancement ofevents in the time-frequency plane

A new elastic model for ground coupling of geophones with spikes

Ground coupling are terms that describe the transfer from seismic ground motion to the motion of a geophone. In previous models, ground coupling was mainly considered as a disk lying on top of a half-space, not considering the fact that in current practice geophones are spiked and are buried for optimal response. In this paper we introduce a new model that captures the spike added to the geophone and models the effect of geophone burial. The geophone is modeled as a rigid, movable cylinder embedded in a half-space near or at the surface. The coupling problem is then tackled by a scattering approach using the elastic form of reciprocity; we consider the vertical component only. The main feature in the coupling function is a resonance whose location and shape depend on the different parameters of the geophone and the soil. In accordance with previous models, adding mass reduces the frequency of resonance. However, we show that pure mass loading assumption is too restrictive for standard geophones. Our new model shows that increasing the spike radius and length decreases the frequency of resonance and the resonance is more peaked. Furthermore, burying the geophone decreases the frequency of resonance, but when one takes into account that the soil at depth is more compact, then the behavior is as observed in practice — namely, an increase in frequency of resonance. As for the properties of the soil, the shear-wave velocity has the largest effect; when increased, it shifts the frequency of resonance to the high-frequency end as desired.GeotechnologyCivil Engineering and Geoscience