Computer processing of vertical seismic profile data

Geophysics ◽  
1983 ◽  
Vol 48 (3) ◽  
pp. 272-287 ◽  
Author(s):  
Myung W. Lee ◽  
Alfred H. Balch
Keyword(s):  
Seismic Profile ◽  
Computer Processing ◽  
Acoustic Properties ◽  
Well Logs ◽  
Seismic Exploration ◽  
Profile Data ◽  
Seismic Profiles ◽  
Vertical Seismic Profiles ◽  
Processing Techniques ◽  
Rock Parameters

Vertical seismic profiles (VSP) are a powerful tool in a variety of seismic exploration situations. Only after extensive computer processing of the raw field data, however, can the full value of this tool be realized. With the help of processing, relations between important rock parameters and acoustic properties can sometimes be established and highly reliable ties from well logs to surface seismic profiles can usually be obtained. The basic theory of the processing techniques is well known. However, the techniques used in processing standard surface seismic profiles usually must be modified to adapt them to the unique conditions associated with VSPs. Processing procedures, and their relevance to the interpretation of VSP and surface seismic profile data, are described.

The use of vertical seismic profiles in seismic investigations of the earth

Geophysics ◽  
1982 ◽  
Vol 47 (6) ◽  
pp. 906-918 ◽  
Author(s):  
A. H. Balch ◽  
M. W. Lee ◽  
J. J. Miller ◽  
Robert T. Ryder
Keyword(s):  
Surface Profile ◽  
Acoustic Properties ◽  
Seismic Exploration ◽  
Seismic Profiles ◽  
Stratigraphic Sequence ◽  
Multiple Channel ◽  
Vertical Seismic Profiles ◽  
Surface Profiling ◽  
The Earth ◽  
Porous Zone

During the past 8 years, the U.S. Geological Survey has conducted an extensive investigation on the use of vertical seismic profiles (VSP) in a variety of seismic exploration applications. Seismic sources used were surface air guns, vibrators, explosives, marine air guns, and downhole air guns. Source offsets have ranged from 100 to 7800 ft. Well depths have been from 1200 to over 10,000 ft. We have found three specific ways in which VSPs can be applied to seismic exploration. First, seismic events observed at the surface of the ground can be traced, level by level, to their point of origin within the earth. Thus, one can tie a surface profile to a well log with an extraordinarily high degree of confidence. Second, one can establish the detectability of a target horizon, such as a porous zone. One can determine (either before or after surface profiling) whether or not a given horizon or layered sequence returns a detectable reflection to the surface. The amplitude and character of the reflection can also be observed. Third, acoustic properties of a stratigraphic sequence can be measured and sometimes correlated to important exploration parameters. For example, sometimes a relationship between apparent attenuation and sand percentage can be established. The technique shows additional promise of aiding surface exploration indirectly through studies of the evolution of the seismic pulse, studies of ghosts and multiples, and studies of seismic trace inversion techniques. Nearly all current seismic data‐processing techniques are adaptable to the processing of VSP data, such as normal moveout (NMO) corrections, stacking, single‐and multiple‐channel filtering, deconvolution, and wavelet shaping.

Traveltime inversion of offset vertical seismic profiles—A feasibility study

Geophysics ◽  
1984 ◽  
Vol 49 (3) ◽  
pp. 250-264 ◽  
Author(s):  
L. R. Lines ◽  
A. Bourgeois ◽  
J. D. Covey
Keyword(s):  
Inverse Method ◽  
Synthetic Data ◽  
Real Data ◽  
Seismic Profile ◽  
Inversion Method ◽  
Earth Model ◽  
Seismic Profiles ◽  
Traveltime Inversion ◽  
Vertical Seismic Profiles ◽  
Inversion Techniques

Traveltimes from an offset vertical seismic profile (VSP) are used to estimate subsurface two‐dimensional dip by applying an iterative least‐squares inverse method. Tests on synthetic data demonstrate that inversion techniques are capable of estimating dips in the vicinity of a wellbore by using the traveltimes of the direct arrivals and the primary reflections. The inversion method involves a “layer stripping” approach in which the dips of the shallow layers are estimated before proceeding to estimate deeper dips. Examples demonstrate that the primary reflections become essential whenever the ratio of source offset to layer depth becomes small. Traveltime inversion also requires careful estimation of layer velocities and proper statics corrections. Aside from these difficulties and the ubiquitous nonuniqueness problem, the VSP traveltime inversion was able to produce a valid earth model for tests on a real data case.

Multichannel Wiener deconvolution of vertical seismic profiles

Geophysics ◽  
1994 ◽  
Vol 59 (10) ◽  
pp. 1500-1511 ◽  
Author(s):  
Jakob B. U. Haldorsen ◽  
Douglas E. Miller ◽  
John J. Walsh
Keyword(s):  
Least Squares ◽  
Amplitude Spectrum ◽  
Seismic Source ◽  
Seismic Profile ◽  
Signal Spectrum ◽  
Seismic Profiles ◽  
Vertical Seismic Profiles ◽  
Vsp Data ◽  
Zero Offset ◽  
Noise Signature

We describe a technique for performing optimal, least‐squares deconvolution of vertical seismic profile (VSP) data. The method is a two‐step process that involves (1) estimating the source signature and (2) applying a least‐squares optimum deconvolution operator that minimizes the noise not coherent with the source signature estimate. The optimum inverse problem, formulated in the frequency domain, gives as a solution an operator that can be interpreted as a simple inverse to the estimated aligned signature multiplied by semblance across the array. An application to a zero‐offset VSP acquired with a dynamite source shows the effectiveness of the operator in attaining the two conflicting goals of adaptively spiking the effective source signature and minimizing the noise. Signature design for seismic surveys could benefit from observing that the optimum deconvolution operator gives a flat signal spectrum if and only if the seismic source has the same amplitude spectrum as the noise.

Tomographic determination of three‐dimensional seismic velocity structure using well logs, vertical seismic profiles, and surface seismic data

Geophysics ◽  
1987 ◽  
Vol 52 (8) ◽  
pp. 1085-1098 ◽  
Author(s):  
Stephen K. L. Chiu ◽  
Robert R. Stewart
Keyword(s):  
Velocity Structure ◽  
Seismic Velocity ◽  
Random Noise ◽  
Three Dimensional ◽  
Real Data ◽  
Well Logs ◽  
Seismic Profiles ◽  
Vertical Seismic Profiles ◽  
The Earth ◽  
Vsp Data

A tomographic technique (traveltime inversion) has been developed to obtain a two‐ or three‐dimensional velocity structure of the subsurface from well logs, vertical seismic profiles (VSP), and surface seismic measurements. The earth was modeled by continuous curved interfaces (polynomial or sinusoidal series), separating regions of constant velocity or transversely isotropic velocity. Ray tracing for each seismic source‐receiver pair was performed by solving a system of nonlinear equations which satisfy the generalized Snell’s law. Surface‐to‐borehole and surface‐to‐surface rays were included. A damped least‐squares formulation provided the updating of the earth model by minimizing the difference between the traveltimes picked from the real data and calculated traveltimes. Synthetic results indicated the following conclusions. For noise‐free cases, the inversion converged closely from the initial guess to the true model for either surface or VSP data. Adding random noise to the observations and performing the inversion indicated that (1) using surface data alone allows reconstruction of the broad velocity structure but with some inaccuracy; (2) using VSP data alone gives a very accurate but laterally limited velocity structure; and (3) the integration of both data sets produces a more laterally extensive, accurate image of the subsurface. Finally, a field example illustrates the viability of the method to construct a velocity structure from real data.

A guide to current uses of vertical seismic profiles

Geophysics ◽  
1985 ◽  
Vol 50 (12) ◽  
pp. 2473-2479 ◽  
Author(s):  
Michael L. Oristaglio
Keyword(s):  
Seismic Exploration ◽  
Significant Advance ◽  
Small Scale ◽  
Seismic Profiles ◽  
Surface Source ◽  
Reflection And Transmission ◽  
Reflected Waves ◽  
Vertical Seismic Profiles ◽  
Transmission Properties ◽  
The Earth

Vertical seismic profiles (VSPs) are small‐scale seismic surveys in which geophones are lowered into a well to record waves traveling both down into the earth (direct waves from the surface source and downgoing multiples) and back toward the surface (primary reflections and upgoing multiples). VSPs thus contain information about the reflection and transmission properties of the earth with a coverage that depends upon the geometry of the VSP experiment and the structure near the well. This article describes the uses of VSPs in seismic exploration that have been published in the last three years and is designed to complement the more detailed surveys by Hardage (1983) and Balch and Lee (1984). When the earth is horizontally layered, the well is vertical, and the source is close to the wellhead, upgoing and downgoing waves recorded by the VSP travel vertically, and the VSP can be used to calibrate surface seismic sections by providing the time‐to‐depth curve and allowing a detailed analysis of reflection and transmission properties of the earth at a given location. These applications rely heavily on signal processing to separate the upgoing and downgoing waves and to study their relationships to data recorded at the surface. When the earth varies laterally or when the source is offset from the well, the VSP can be used to complement surface surveys by providing high‐resolution images of structure near the well. Current work has concentrated on forming images from the reflected waves by the methods of common‐depth‐point (CDP) stacking and migration. Tomographic methods for inverting the traveltimes and amplitudes of transmitted waves are also being developed and will become important when downhole arrays and powerful downhole sources are available. The most significant advance in the next few years, however, will be the development of a reliable three‐axis tool with internal devices for determining both the orientation of the tool and the quality of its coupling to the borehole wall.

scholarly journals The Challenge of Interpreting 3-D Seismic in Shaybah Field, Saudi Arabia

GeoArabia ◽  
1998 ◽  
Vol 3 (2) ◽  
pp. 209-226
Author(s):  
Mohammed N. Alfara ◽  
Edgardo L. Nebrija ◽  
Michael D. Ferguson
Keyword(s):  
Saudi Arabia ◽  
Sand Dunes ◽  
Seismic Profiles ◽  
Well Control ◽  
Vertical Seismic Profiles ◽  
Weak Reflection ◽  
Correction Problem ◽  
Zero Offset ◽  
Borehole Seismic ◽  
Processing Techniques

ABSTRACT The giant Shaybah field, situated in the northeastern Rub’ Al-Khali Desert in Saudi Arabia, was discovered in 1968. 2-D seismic and well control were used at the time to delineate the field. A 3-D seismic program was launched in 1993 to develop a detailed geological picture of the field. Over 120 million seismic traces, covering an area of about 1,100 square kilometers, were acquired in flat sabkhas and high sand dunes. The dunes, exceeding 200 meters in height in places, posed a severe statics correction problem. Up to 200 milliseconds of time correction was sometimes applied to the seismic traces in order to compensate for sand-related statics. Also, as verified by vertical seismic profiles, the reservoir level was severely obscured by strong multiples. In addition to complex topography and multiples, the 3-D structural seismic interpretation had to overcome two further problems. First, the lithology of the gas-capped Shu’aiba reservoir consists predominantly of carbonates which are sealed by a denser, compacted shale. The decrease in density and increase in velocity, at the top of the Shu’aiba reservoir, result in a weak reflection. Second, the top of the Shu’aiba reservoir undulates as a result of rudist build-ups and therefore is not conformable with its base. For these reasons, the top of the Shu’aiba reservoir cannot be mapped as a “phantom” of the much better reflection from the base of the reservoir. To resolve the uncertainties described above, borehole seismic measurements (specifically offset and zero-offset vertical seismic profiles in vertical wells) were incorporated. These additional measurements provided the required calibration of the seismic, and hence the validation of the structural interpretation. These borehole surveys continue to serve as a reference for on-going efforts to further improve the data quality using more advanced processing techniques.

New insights into the structure of the Sudbury Igneous Complex from downhole seismic studies

2002 ◽  
Vol 39 (6) ◽  
pp. 943-951 ◽  
Author(s):  
David Snyder ◽  
Gervais Perron ◽  
Karen Pflug ◽  
Kevin Stevens
Keyword(s):  
Seismic Data ◽  
Seismic Profile ◽  
Seismic Profiles ◽  
Igneous Complex ◽  
Impact Melt ◽  
Vertical Seismic Profiles ◽  
Sudbury Igneous Complex ◽  
Common Depth Point ◽  
Deformation Models ◽  
The Impact

New vertical seismic profiles from the northwest margin of the Sudbury impact structure provide details of structural geometries within the lower impact melt sheet (usually called the Sudbury Igneous Complex) and the sublayer norite layer. Vertical seismic profile sections and common depth point transformation images display several continuous reflections that correlate with faults and stratigraphic boundaries logged from drill cores. Of four possible mechanisms that explain repeated rock units, late-stage flow or normal faulting that occurred within the last layers to cool and crystallize might best explain the observations, especially the most prominent reflectors observed in the seismic data. These results reaffirm previously proposed two-stage cooling and deformation models for the impact melt sheet.

Synthetic finite‐offset vertical seismic profiles for laterally varying media

Geophysics ◽  
1985 ◽  
Vol 50 (4) ◽  
pp. 627-636 ◽  
Author(s):  
George A. McMechan
Keyword(s):  
Drill Hole ◽  
Seismic Profile ◽  
Rock Properties ◽  
Seismic Profiles ◽  
One Dimensional ◽  
Vertical Seismic Profiles ◽  
Vsp Data ◽  
Lateral Variations ◽  
Lateral Structure

The analysis of vertical seismic profile (VSP) data is generally directed toward determination of rock properties (such as velocity, impedance, attenuation, and anisotropy) as functions of depth (that is, in a one‐dimensional model). If VSPs are extended to include observations from sources at multiple, finite offsets, then lateral variation in structure near the drill hole can be studied. Synthetic offset VSPs are computed by an acoustic finite‐difference algorithm for two‐dimensional models that include the main types of structural traps. These show that diagnostic lateral variations can be detected and interpreted in VSPs. In a VSP, lateral structure variations may produce changes in the type and number of arrivals, in amplitudes, in time and phase shifts, in interference patterns, in curvature of arrival branches, and in the focusing and defocusing of energy. All of these effects are functions of the positions of the source(s) and receiver(s); numerical modeling is a potentially useful tool for interpretation of VSP data from laterally varying structure.

Migration-based filtering: Applications to geophysical imaging data

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. S219-S228 ◽  
Author(s):  
Jianjian Huo ◽  
Binzhong Zhou ◽  
Qing Zhao ◽  
Iain M. Mason ◽  
Ying Rao
Keyword(s):  
Seismic Profile ◽  
Stoneley Wave ◽  
Imaging Data ◽  
Seismic Profiles ◽  
Coherent Signals ◽  
Vertical Seismic Profiles ◽  
Full Waveform ◽  
Ground Roll ◽  
Geophysical Imaging ◽  
Sonic Logging

Migration is used to collapse “diffractions,” i.e., to focus hyperbolic events that appear in the space-time of a seismic profile — into spots of finite area in the image space. These usually represent scattering objects. However, there are situations in which some of the energy can be focused by migration, and muted without significantly damaging the remaining echoes. Demigration or forward modeling then restores the remaining data, and the removed signals can be rebuilt by subtracting these restored data from the original records. This process can be classified as migration-based filtering. It is demonstrated by synthetic and field data that this filter can be used for suppressing unwanted coherent signals or separating/extracting wavefields of interest: (1) the suppression of ground roll in seismic shot gathers, (2) the suppression of axially guided arrivals in borehole radar profiles, (3) suppressing the direct arrivals to enhance Stoneley-wave reflections in full-waveform sonic logging data, and (4) separating up- and downgoing waves in vertical seismic profiles.

Wave‐field transformations of vertical seismic profiles

Geophysics ◽  
1987 ◽  
Vol 52 (3) ◽  
pp. 307-321 ◽  
Author(s):  
Liang‐Zie Hu ◽  
George A. McMechan
Keyword(s):  
Fourier Transform ◽  
Wave Field ◽  
Seismic Profile ◽  
Seismic Profiles ◽  
P Waves ◽  
S Waves ◽  
Vertical Seismic Profiles ◽  
Slice Theorem ◽  
Vsp Data ◽  
T Domain

Vertical seismic profile (VSP) data may be partitioned in a variety of ways by application of wave‐field transformations. These transformations provide insights into the nature of the data and aid in the design of processing operations. Transformations are implemented in a reversible sequence that takes the observed VSP data from the depth‐time (z-t) domain through the slowness‐time intercept (p-τ) domain (by a slant stack), to the slowness‐frequency (p-ω) domain (by a 1-D Fourier transform over τ), to the wavenumber‐frequency (k-ω) domain (by resampling using the Fourier central‐slice theorem), and finally back to the z-t domain (by an inverse 2-D Fourier transform). Multidimensional wave‐field transformations, combined with k-ω, p-ω, and p-τ filtering, can be applied to wave‐field resampling, interpolation, and extrapolation; separation of P-waves and S-waves; separation of upgoing and downgoing waves; and wave‐field decomposition for isolation, identification, and analysis of arrivals.

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