A petroleum geologist's guide to seismic reflection. (2011)

• Record Type: Book
• Other Titles: Guide to seismic reflection
• Further Information: Note: William Ashcroft.
• Other Names: Ashcroft, W. A (William A.)
• Contents: Preface xi Acknowledgements xiii Part I Basic topics and 2D interpretation. 1 Introduction and overview 3 1.1 Exploration geophysics in petroleum exploration 3 1.2 The principle of seismic reflection surveying 3 1.3 Overview of the seismic reflection industry 4 1.4 A brief history of seismic surveying 5 1.5 Societies, books and journals 5 2 Geophysical signal description 6 2.1 Overview 6 2.2 Cosine waves 6 2.3 Signals and spectra 8 2.4 Periodic waveforms: Fourier series 8 2.5 Seismic wavelets 9 2.6 Wavelet characteristics: time and frequency domains 10 2.7 Digitization of signals 12 2.8 Fourier description of space-dependent quantities 13 Tutorials: 13 Tutorial 2.1 Consolidating ideas of frequency and phase shift 13 Tutorial 2.2 Fourier summation of a periodic waveform 14 Tutorial 2.3 The transition from periodic waveform to wavelet: program FOURSYN 15 Tutorial 2.4 Amplitude and phase-shift changes in the wavelet: program FOURSYN 15 3 Data acquisition 17 3.1 General points 17 3.2 Seismic sources and receivers 17 3.3 Static corrections 18 3.4 Recording and presentation of data 18 3.5 Common mid-point (CMP) shooting 19 3.6 The attack on noise 20 3.7 3D surveys 22 4 Seismic wave propagation 24 4.1 Introduction 24 4.2 P-wave 24 4.3 Controls on P-wave velocity 24 4.4 P-wave waveforms 26 4.5 Shear waves and surface waves 26 4.6 P-wave attenuation 27 4.6.1 Spherical spreading 27 4.6.2 Frequency-dependent attenuation 27 4.7 P-wave transmission paths 27 4.7.1 Wavefronts and raypaths for a single interface 28 4.7.2 Reflection coefficient and wavelet polarity 29 4.7.3 Ray-tracing in seismic modelling 29 Tutorials: 30 Tutorial 4.1 P- and S-wave particle motion on screen: program PSWAVE 30 Tutorial 4.2 Basic measurements of time, velocity and depth 30 Tutorial 4.3 Drawing the reflection wavefront from Huygens's Principle 30 Tutorial 4.4 Calculating typical reflection coefficients from well data 31 5 The process of reflection 33 5.1 Introduction 33 5.2 Fresnel zones 33 5.3 Fresnel zones and the seismic reflection 33 5.4 Faults and diffractions 34 5.5 Hyperbolae on stacked time sections 35 5.6 The reflection as a summation of hyperbolae 36 5.7 Resolution of the seismic reflection method 36 5.8 Multiple reflections: common modes 37 5.9 Multiples: the scale of the problem 38 Tutorials: 39 Tutorial 5.1 Seismic expression of a ‘point’ reflector 39 Tutorial 5.2 Water-layer multiples spoil a deep reservoir interval: program CMPGATHER 39 6 Velocity analysis, CMP stacking and post-stack migration 41 6.1 General points 41 6.2 Definitions of seismic velocity: well data 41 6.3 Velocities from seismic data: Vrms 42 6.4 Velocities from seismic data: Vstack 42 6.5 Velocity analysis 44 6.6 Errors in seismic-derived velocities 44 6.7 Multiple suppression by CMP stacking 45 6.8 Stacking the whole section: a make-or-break process 45 6.9 Some stacking refinements 45 6.9.1 NMO stretch 45 6.9.2 Weighted stacking 46 6.10 Migration: the fundamental idea 46 6.10.1 Map migration 46 6.11 Full-waveform migration 47 6.11.1 Migration by Kirchhoff diffraction stack 47 6.11.2 Migration by wave equation 47 6.12 Migration example: 2D section 48 Tutorials: 49 Tutorial 6.1 Velocities from well data 49 Tutorial 6.2 NMO correction, CMP stacking and velocity analysis: program NMOSTAK 50 Tutorial 6.3 Picking stacking velocities from a velocity spectrum: programs VELSPEC and SEGY2D 51 Tutorial 6.4 Suppression of multiples by CMP stacking: program NMOSTAK 51 Tutorial 6.5 How multiples appear on a velocity spectrum: program VELSPEC 51 Tutorial 6.6 Migration by ray-tracing 52 7 Interpretation of two-dimensional (2D) surveys for structure 53 7.1 Introduction 53 7.2 Linking well geology to the seismic section 53 7.2.1 Sonic log or continuous velocity log (CVL) 53 7.2.2 Time-depth plot 53 7.2.3 Making the link: synthetic seismogram 54 7.3 Choosing reflections to pick 54 7.4 Picking reflections 55 7.5 Sideswipe 55 7.6 A sideswipe example: fault diffractions 56 7.7 Preparing structure maps in TWT 57 7.8 Time to depth conversion 58 7.8.1 Velocity as an analytical function of depth 59 7.8.2 Time-depth conversion strategies 59 7.9 Examples of time-depth conversion 59 7.9.1 Southern North Sea: Rotliegend sandstone target 59 7.9.2 Central North Sea: Paleocene sands target 60 7.9.3 West Sole field, southern North Sea 60 Tutorials: 60 Tutorial 7.1 Constructing a synthetic seismogram from well-log data: program SYNTH 60 Tutorial 7.2 Matching a synthetic seismogram to seismic data: program IMAGES 62 Tutorial 7.3 Picking reflections along a 2D section from the Moray Firth, northern North Sea basin 62 Tutorial 7.4 Time to depth conversion, West Sole Field, southern North Sea Basin 70 Part II Seismic input to reservoir characterization. 8 Better images of the subsurface 81 8.1 Introduction 81 8.2 Reflection point dispersal, conflicting dips and DMO 81 8.3 Prestack time migration (PSTM) 82 8.3.1 Common-offset sections and the Cheops pyramid 82 8.3.2 PSTM and image gathers 83 8.3.3 The limitations of PSTM: lateral variations in velocity 85 8.4 Prestack depth migration (PSDM) 85 8.4.1 Velocity-depth model based on layers 87 8.4.2 Velocity-depth model based on tomography 87 8.5 Anisotropy: the ultimate refinement in velocity 89 8.6 Velocity-depth ambiguity 90 8.7 Future migration technique: Kirchhoff or wave extrapolation? 91 8.8 3D migration 91 8.9 3D seismic interpretation 93 8.10 Growth and impact of 3D seismic surveys 94 Tutorials: 95 Tutorial 8.1 Reflection point dispersal 95 Tutorial 8.2 Lateral mis-location from time migration 96 Tutorial 8.3 3D data: vertical section and time-slice 97 9 Modifying the seismic waveform 98 9.1 Introduction 98 9.2 Testing an electronic filter: the impulse response 98 9.3 Digital filters: convolution 98 9.4 Cross-correlation and auto-correlation 101 9.5 Frequency filtering by convolution 102 9.6 The seismogram as a convolution 103 9.7 Deconvolution 103 9.8 Designing deconvolution operators 104 9.9 Predictive deconvolution 105 9.10 Wavelet processing 105 9.11 Frequency-domain processing 105 9.12 Data processing and the fragility of bandwidth 106 Tutorials: 107 Tutorial 9.1 Digital filtering by hand 107 Tutorial 9.2 The power of the Vibroseis technique: program SIGPROC 107 Tutorial 9.3 Testing the seismic response of a geological model: program SYNTH 108 10 Refining reservoir architecture from seismic data 109 10.1 Introduction: the reservoir model 109 10.2 Refining reservoir environment: seismic stratigraphy and facies analysis 109 10.2.1 Sequences and system tracts 109 10.2.2 Picking seismic sequence boundaries 109 10.2.3 Seismic facies analysis 110 10.2.4 Sedimentary units as 3D volumes 110 10.2.5 Multi-attribute
• Publisher Details: Place of publication not identified : Wiley-Blackwell
• Publication Date: 2011
• Extent: 1 online resource (176 pages)
• Subjects: 622.1828; Seismic reflection method; Petroleum -- Prospecting
• Languages: English
• ISBNs: 9781444397864
• Access Rights: Legal Deposit; Only available on premises controlled by the deposit library and to one user at any one time; The Legal Deposit Libraries (Non-Print Works) Regulations (UK).
• Access Usage: Restricted: Printing from this resource is governed by The Legal Deposit Libraries (Non-Print Works) Regulations (UK) and UK copyright law currently in force.