Abstract Seventeen papers based on talks and posters presented at 7IWSA are included in this book: In “General constitutive relations for layered media,” Schoenberg provides a combination of matrix algebra and group theory to offer a formalism for evaluating of the properties of the unique homogeneous anisotropic medium that is statically equivalent to a stationary distribution of homogeneous, but generally anisotropic, fine layers. The method is valid for systems representing fluid permeability, heat conductivity, and electrical properties such as electrical conductivity, dielectric permittivity, and magnetic permeability. Additionally, the formalism extends to higher dimensional elastic layered systems so that bi-anisotropic electromagnetic and piezoelectric layered systems can be studied. “Upscaling: Elastic anisotropy from ultrasonic laboratory measurements to borehole seismic surveys,” by Hornby, applies the equivalent media theory of Backus (1962) to resolve discrepancies in anisotropic parameters for transversely isotropic media derived from ultrasonic laboratory measurements and seismic-scale VSP surveys. Hornby argues that the inversion of laboratory experiments generally leads to larger values of the δ parameter of Thomsen (1986), as well as smaller values for the normalized anisotropy parameter η proposed by Alkalifah and Tsvankin (1994). The difference is attributed to the effect of fine-scale layering on the larger wavelength VSP measurements. Hornby tests this hypothesis by the upscaling of elastic constants determined from in-situ depth-continuous borehole measurements. Although borehole measurements cannot resolve the complete set of elastic constants, remaining parameters are estimated from representative laboratory measurements of borehole samples. The resulting values for the anisotropic parameters δ and η are comparable to those determined from the VSP survey with remaining differences attributed to the effect of unresolved finer-scale layering. In “Can we separate the effects of anisotropy and structure from surface seismic data?” Kuehnel and Li offer a practical method of correcting traveltimes for reflections in transversely isotropic media. They present a method of decomposing the traveltime equation for a reflected wave in a transversely isotropic layer in terms of dip and anisotropy, based on the traveltime of individual wavetype using an iterative procedure applied to a ray-tracing code. In “ P -wave traveltime anomalies below a dipping anisotropic thrust sheet,” Leslie and Lawton raise the awareness of the complications that can arise from this common subsurface configuration and begin to quantify the anisotropic effect in depth migration. Results from physical modeling and numerical ray tracing show that isotropic depth migration and velocity analysis produce significant artifacts in the synthetic data from such a model. Therefore, it is suggested that care be taken when using the isotropic assumption in depth migration even with the presence of mild anisotropy.

Abstract Papers in this volume explore the potential of a variety of seismic inversion methods applied to the same data set. They cover a wide range of topics, including effects of rock properties on seismic response, preparation of seismic data for AVO analysis, and a variety of AVO and inversion methods. The papers are an extension of a 1994 SEG postconvention workshop.

Abstract With more than 75 color illustrations, this book demonstrates the utility of VSP processing and interpretation. In Chapter 1, ȜAcquisition Considerations,” the authors describe how VSP surveys differ from other borehole and surface seismic methods and define the geometries and nomenclatures used throughout the book. In Chapter 2, “Integrated Interpretive Processing,” they describe the interpretive processing methodology and processing procedures applied to the VSP data incorporated into the case histories in Chapters 3 through 6. The basic mathematics behind the wavefield separation, deconvolution, and far-offset processing of VSP data are reviewed in more detail in the appendix. Chapters 3 through 6 are case studies of carbonate reef and sandstone exploration plays from the western Canadian Sedimentary Basin. For each case study, the authors discuss the relevant geology and the interpretation of the existing seismic coverage prior to the drilling of the VSP well, the well results and the rationale behind recording the VSP data, the reevaluation of the surfaceseismic coverage based on the VSP and associated well control, and the utility of the respective VSP survey.

Abstract This book provides a bibliography of the material available concerning geophysical applications of spectral analysis. There are in all 1,483 numbered references. In addition to methodical developments, this bibliography includes geophysical applications.

Abstract This book is devoted to one important aspect of development of physical foundations of the seismic method — the theory of edge diffraction phenomena. Thoese phenomena occur when conditions of the regular wave reflection/transmission change sharply. Though these phenomena drew the attention of many scientist for many decades, their real influence on the resolution ability of the seismic method was truly understood rather recently due to interpretation of seismic data in block structures. Clearly, to develop seismic method for investigation of such structures without developing the theory of edge diffraction phenomena is impossible. The latter is the aim of this book. The seismic method is based on the fundamental laws of continuum mechanics. These laws describe the behavior of wavefields on the microscopic level, i.e., in the form of differential equations of motion. Integrating these equations under some initial conditions or boundary conditions, makes possible acquisition of all necessary information on the wavefield in the given situation. However, the working base of the seismic method consists of not only the differential equations of motion themselves but of some general and simple enough consequences of their solutions, which are formulated in the form of physical principles and l aws. The latter include the concepts of wave, Fermat’s principle, the law of conservation of the energy flux, and the reflection/transmission laws. Essentially these laws and principles must form a system of concepts sufficient for the solution of some class of typical interpretation problems. In fact, these principles and laws form the physical fo ndation of the seismic method.