Frequency Content Of Seismic Data Research Articles

Ground roll attenuation based on an empirical curvelet transform

In the field of seismic exploration, ground roll seriously affects the deep effective reflections from subsurface deep structures. Traditional curvelet transform cannot provide an adaptive basis function to achieve a suboptimal denoised result. In this paper, we propose a method based on empirical curvelet transform (ECT) for ground roll attenuation. Unlike the traditional curvelet transform, this method not only decomposes seismic data into multiscale and multi-directional components, but also provides an adaptive filter bank according to frequency content of seismic data itself. So, ground roll can be separated by using this method. However, as the frequency of reflection and ground roll components are close, we apply singular value decomposition (SVD) in the curvelet domain to differentiate the ground roll and reflection better. Examples of synthetic and field seismic data reveal that the proposed method based ECT performs better than the traditional curvelet method in terms of the suppression of ground roll.

Investigation of Preprocessing for Seismic Attenuation Profiling to Image the Earthquake Swarm Associated with the 2000 Eruption of the Miyakejima Volcano in Japan

By using profiling that focuses on seismic attenuation instead of reflectivity, we investigate geological structures in volcanic areas and fractured areas, where seismic reflections are difficult to observe. A previous study successfully visualized the hypocenter distribution of the earthquake swarm associated with the 2000 Miyakejima eruption from the seismic attenuation profile of a seismic line. However, any significant geologic features were not figured out on other nearby lines. In this paper, we re-evaluated our preprocessing of the seismic reflection data, which are the input for the seismic attenuation profiling method, with an eye toward improving frequency preservation. First, deconvolution was excluded from the preprocessing sequence, because it can potentially change the frequency content of seismic data. Second, a very small NMO stretching factor of 0.1, which does not allow reflections to stretch more than 10%, was adopted to minimize the frequency distortion by NMO correction. As a result, clear high-attenuation anomalies showed up on seismic attenuation profiles of the other nearby lines, which are consistent with typical geological features known in the study area: earthquake swarm and volcanic activity. This paper demonstrates that appropriate preprocessing was able to improve the accuracy of imaging geological structures by seismic attenuation profiling.

Resolving subtle stratigraphic features using spectral ridges and phase residues

Seismic interpretation is dependent on the quality and resolution of seismic data. Unfortunately, seismic amplitude data are often insufficient for detailed sequence stratigraphy interpretation. We reviewed a method to derive high-resolution seismic attributes based upon complex continuous wavelet transform pseudodeconvolution (PD) and phase-residue techniques. The PD method is based upon an assumption of a blocky earth model that allowed us to increase the frequency content of seismic data that, for our data, better matched the well log control. The phase-residue technique allowed us to extract information not only from thin layers but also from interference patterns such as unconformities from the seismic amplitude data. Using data from a West Texas carbonate environment, we found out how PD can be used not only to improve the seismic well ties but also to provide sharper sequence terminations. Using data from an Anadarko Basin clastic environment, we discovered how phase residues delineate incised valleys seen on the well logs that are difficult to see on vertical slices through the original seismic amplitude.

Geophysical methods of oil and gas exploration in cambrian and precambrian sedimentary rocks of the Siberian Platform

The Siberian Platform is the largest hydrocarbon-bearing sedimentary basin in the USSR. The conditions encountered in geophysical exploration in this basin are uniquely difficult. This very old sedimentary complex is characterised by abrupt changes in physical properties reflecting the presence of dolerites and tuffs, changes in salt thickness, and complex structure. Petroleum traps are controlled by low amplitude structures in the salt complex, although reservoir properties are variable, so that most traps are stratigraphic. This leads to the use of frequency content of seismic data to identify traps and electrical and time domain EM techniques to confirm the presence of the traps.