3C Seismic and VSP: Converted waves and vector wavefield applications


Book Description

3C seismic applications provide enhanced rock property characterization of the reservoir that can complement P-wave methods. Continued interest in converted P- to S-waves (PS-waves) and vertical seismic profiles (VSPs) has resulted in the steady development of advanced vector wavefield techniques. PS-wave images along with VSP data can be used to help P-wave interpretation of structure in gas obscured zones, of elastic and fluid properties for lithology discrimination from S-wave impedance and density inversion in unconventional reservoirs, and of fracture characterization and stress monitoring from S-wave birefringence (splitting) analysis. The book, which accompanies the 2016 SEG Distinguished Instructor Short Course, presents an overview of 3C seismic theory and practical application: from fundamentals of PS-waves and VSPs, through to acquisition and processing including interpretation techniques. The emphasis is on unique aspects of vector wavefields, anisotropy, and the important relationships that unify S-waves and P-waves. Various applications and case studies demonstrate image benefits from PS-waves, elastic properties and fluid discrimination from joint inversion of amplitude variations with offset/angle (AVO/A), and VSP methods for anisotropic velocity model building and improved reservoir imaging. The book will be of interest to geophysicists, geologists, and engineers, especially those involved with or considering the use of AVO/A inversion, fracture/stress characterization analyses, or interpretation in gas-obscured reservoirs.







Advances in Geophysics


Book Description

Advances in Geophysics is a highly-respected publication in the field of geophysics. Since 1952, each volume has been eagerly awaited, frequently consulted, and praised by researchers and reviewers alike. Now with over 50 volumes, the series contains much material still relevant today – truly an essential publication for researchers in all fields of geophysics. Provides high-level reviews of the latest innovations in geophysics Written by recognized experts in the field Presents an essential publication for researchers in all fields of geophysics




Land Seismic Case Studies for Near-Surface Modeling and Subsurface Imaging


Book Description

Written for practicing geophysicists, “Land Seismic Case Studies for Near-Surface Modeling and Subsurface Imaging” is a comprehensive guide to understanding and interpreting seismic data. The culmination of land seismic data acquisition and processing projects conducted by the author over the last two decades, this book contains more than nearly 800 figures from worldwide case studies—conducted in both 2D and 3D. Beginning with Chapter 1 on seismic characterization of the near-surface, Chapter 2 presents near-surface modeling by traveltime and full-wave inversion, Chapter 3 presents near-surface modeling by imaging, and then Chapter 4 includes detailed case studies for near-surface modeling. Chapter 5 reviews single- and multichannel signal processing of land seismic data with the key objective of removing surface waves and guided waves that are characterized as coherent linear noise. Uncommon seismic data acquisition methods, including large-offset acquisition in thrust belts to capture the large-amplitude supercritical reflections, swath-line acquisition, and joint PP and SH- SH seismic imaging are highlighted in Chapter 6, and Chapter 7 presents image-based rms velocity estimation and discusses the problem of velocity uncertainty. The final two chapters focus exclusively on case studies: 2D in Chapter 8 and 3D in Chapter 9. An outstanding teaching tool, this book includes analysis workflows containing processing steps designed to solve specific problems. Essential for anyone involved in acquisition, processing, and inversion of seismic data, this volume will become the definitive reference for understanding how the variables in seismic acquisition are directly reflected in the data.




Advances in ocean bottom seismology


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S-wave Velocity Estimation Using Converted-wave VSP Data


Book Description

One of the key benefits of zero-offset vertical seismic profile (VSP) is to provide accurate velocity information in the vicinity of boreholes. For 3-component VSP, we usually pick the first break times of direct downgoing S-wave to estimate the S-wave velocity. However, the direct downgoing S-wave arrivals may be too weak to pick precisely. To mitigate this disadvantage, I present a new S-wave velocity estimation method using converted (P-to-S) waves in VSP data. Traveltimes of the strongest converted PS-wave are used to build an S-wave velocity model. Two synthetic traveltime datasets are generated and used to test the method. The first one, without noise, is used to investigate the sensitivities of results to different initial models. The inversion results are slightly different: the RMS error between the true velocity and the inverted velocity varies from 1 m/s to 10 m/s for different initial models. The second test, with random noise, explores the sensitivities of results to errors in picked traveltimes. Results show that the RMS error of output velocity varies from 2 m/s to 92 m/s when the RMS error of input traveltimes ranges from 0.1 ms to 8 ms. In addition to the synthetic tests, real 3-component zero-offset VSP and offset VSP datasets from the Huabei oil field, China are examined using the proposed method. The VSP survey used a dynamite source and 3-component receivers, with the receiver depth from 360 m to 2020 m. The inversion results show that, from 360 m to 900 m depths, the S-wave velocity derived from offset VSP fits quite well with that obtained from zero-offset VSP. The Vp/Vs is approximated 2.8 and the lithology is mudstone with sandstone. From 910 m to 2020 m, the S-wave velocity derived from offset VSP is close to that from zero-offset VSP. The Vp/Vs is around 1.7 and the lithology is primarily limestone and dolomite.




Petroleum Geology


Book Description

Accompanying DVD-ROM includes "links between the text and an extensive selection of core photographs and seismic animations illustrating the many exploration models described."




Planning Land 3-D Seismic Surveys


Book Description