Practical Seismic Data Analysis

From the previous chapters the reader should have become acquainted with many of the basic skills of seismic data analysis. Any practice of seismic data processing utilizes some of these skills to solve particular problems, and uses special tools to address more focused issues. Everyone in this field will encounter special issues in his/her career; hence knowing the common features of some special topics is very useful. In this chapter several special processing topics are reviewed to show the use of the basic data processing skills that we have learned, and to expose the reader to some widely seen processing topics. Each of these topics deals with issues associated with a particular problem or property. The first section introduces the issues involved in four aspects of seismic data acquisition: monitoring of source signals including fracking-induced micro-seismicity; monitoring background noises; seismic illumination analysis; and preservation of low-frequency signals. The second section is on suppression of multiple reflections, which is of service to many conventional seismic imaging methods that use only primary reflections. After defining common types of multiples, three classes of multiple suppression methods are introduced. The first is based on the differential moveout between primaries and multiples; the second exploits the periodicity of the multiples; and the third reduces all surface-related multiple energy via pre-stack inversion. The next section reviews the basics in seismic anisotropy, a property of the medium that causes a variation of the speed of seismic waves as a function of the traversing angle. Information on seismic anisotropy helps in improving the fidelity of seismic imagery in fault imaging, and in detecting the dominant orientations of fractures. The fourth section briefly covers multi-component seismic data processing, with an analysis of its pros and cons and with illustrations in wavefield separation, converted wave processing, and VSP data processing. The final section introduces the processing aspect of seismic attributes, including a variety of localized attributes, geometric attributes, and texture attributes, plus related processing in seismic-to-well tie and impedance inversion. To become an expert in the practice of these and other topics in seismic data processing, the reader must learn the fundamentals of seismic wave and ray theory, common issues in seismic data acquisition, processing and interpretation, and spend some time in processing and utilizing field seismic data.