PRACTICAL USE OF BOREHOLE SEISMIC IN EXPLORATION

1984 ◽  
Vol 24 (1) ◽  
pp. 429
Author(s):  
F. Sandnes W. L. Nutt ◽  
S. G. Henry
Keyword(s):  
Seismic Data ◽  
Seismic Profile ◽  
Seismic Survey ◽  
Vertical Seismic Profile ◽  
Direct Signal ◽  
Seismic Fault ◽  
Time Calibration ◽  
Vsp Data ◽  
Borehole Seismic ◽  
Processing Techniques

The improvement of acquisition and processing techniques has made it possible to study seismic wavetrains in boreholes.With careful acquisition procedures and quantitative data processing, one can extract useful information on the propagation of seismic events through the earth, on generation of multiples and on the different reflections coming from horizons that may not all be accessible by surface seismic.An extensive borehole seismic survey was conducted in a well in Conoco's contract area 'Block B' in the South China Sea. Shots at 96 levels were recorded, and the resulting Vertical Seismic Profile (VSP) was carefully processed and analyzed together with the Synthetic Seismogram (Geogram*) and the Synthetic Vertical Seismic Profile (Synthetic VSP).In addition to the general interpretation of the VSP data, i.e. time calibration of surface seismic, fault identification, VSP trace inversion and VSP Direct Signal Analysis, the practical inclusion of VSP data in the reprocessing of surface seismic data was studied. Conclusions that can be drawn are that deconvolution of surface seismic data using VSP data must be carefully approached and that VSP can be successfully used to examine phase relationships in seismic data.

Integrated prestack depth migration of vertical seismic profile and surface seismic data from the Rocky Mountain Foothills of southern Alberta, Canada

Geophysics ◽  
2003 ◽  
Vol 68 (6) ◽  
pp. 1782-1791 ◽  
Author(s):  
M. Graziella Kirtland Grech ◽  
Don C. Lawton ◽  
Scott Cheadle
Keyword(s):  
Seismic Data ◽  
Rocky Mountain ◽  
Velocity Model ◽  
Seismic Profile ◽  
Vertical Seismic Profile ◽  
Prestack Depth Migration ◽  
Data Set ◽  
Depth Migration ◽  
Southern Alberta ◽  
Vsp Data

We have developed an anisotropic prestack depth migration code that can migrate either vertical seismic profile (VSP) or surface seismic data. We use this migration code in a new method for integrated VSP and surface seismic depth imaging. Instead of splicing the VSP image into the section derived from surface seismic data, we use the same migration algorithm and a single velocity model to migrate both data sets to a common output grid. We then scale and sum the two images to yield one integrated depth‐migrated section. After testing this method on synthetic surface seismic and VSP data, we applied it to field data from a 2D surface seismic line and a multioffset VSP from the Rocky Mountain Foothills of southern Alberta, Canada. Our results show that the resulting integrated image exhibits significant improvement over that obtained from (a) the migration of either data set alone or (b) the conventional splicing approach. The integrated image uses the broader frequency bandwidth of the VSP data to provide higher vertical resolution than the migration of the surface seismic data. The integrated image also shows enhanced structural detail, since no part of the surface seismic section is eliminated, and good event continuity through the use of a single migration–velocity model, obtained by an integrated interpretation of borehole and surface seismic data. This enhanced migrated image enabled us to perform a more robust interpretation with good well ties.

Imaging below a complex overburden with borehole-seismic data

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. S135-S150
Author(s):  
Jakob B. U. Haldorsen ◽  
Leif Jahren
Keyword(s):  
Economic Evaluation ◽  
Seismic Data ◽  
Seismic Profile ◽  
Profile Data ◽  
Vertical Seismic Profile ◽  
S Waves ◽  
Critical Information ◽  
Measured Polarization ◽  
Borehole Seismic

We have determined how the measured polarization and traveltime for P- and S-waves can be used directly with vertical seismic profile data for estimating the salt exit points in a salt-proximity survey. As with interferometry, the processes described use only local velocities. For the data analyzed in this paper, our procedures have confirmed the location, inferred from surface-seismic data, of the flank of a steeply dipping salt body near the well. This has provided us more confidence in the estimated reservoir extent moving toward the salt face, which in turn has added critical information for the economic evaluation of a possible new well into the reservoir. We also have found that ray-based vector migration, based on the assumptions of locally plane wavefronts and locally plane formation interfaces, can be used to create 3D reflection images of steeply dipping sediments near the well, again using only local velocities. Our local reflection images have helped confirm the dips of the sediments between the well and the salt flank. Because all parameters used in these processes are local and can be extracted from the data themselves, the processes can be considered to be self-sufficient.

Antialiasing condition and filter for the reciprocity equation of correlation type

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. WB219-WB224 ◽  
Author(s):  
Weiping Cao ◽  
Gerard T. Schuster
Keyword(s):  
Seismic Data ◽  
Seismic Profile ◽  
Numerical Results ◽  
Numerical Implementation ◽  
Vertical Seismic Profile ◽  
Vsp Data ◽  
And Migration

An antialiasing formula has been derived for interferometric redatuming of seismic data. More generally, this formula is valid for numerical implementation of the reciprocity equation of correlation type, which is used for redatuming, extrapolation, interpolation, and migration. The antialiasing condition can be, surprisingly, more tolerant of a coarser trace sampling compared to the standard antialiasing condition. Numerical results with synthetic vertical seismic profile (VSP) data show that interferometry artifacts are effectively reduced when the antialiasing condition is used as a constraint with interferometric redatuming.

scholarly journals Subsalt Depth Imaging Using 3-D VSP Technique in the Ras El Ush Field, Gulf of Suez, Egypt

GeoArabia ◽  
1999 ◽  
Vol 4 (3) ◽  
pp. 363-378
Author(s):  
Mohammed A. Badri ◽  
Taha M. Taha ◽  
Robert W. Wiley
Keyword(s):  
Seismic Data ◽  
Seismic Profile ◽  
Poor Quality ◽  
Gulf Of Suez ◽  
Geological Model ◽  
Vertical Seismic Profile ◽  
Depth Imaging ◽  
Vsp Data ◽  
Basement High ◽  
Definition Of

ABSTRACT In 1995 oil was discovered in the pre-Miocene Matulla and Nubia Sandstones in the Ras El Ush field, Gulf of Suez, Egypt. The discovery was based on an aeromagnetic anomaly from a basement high. After drilling several delineation wells, based on a geological model, it became evident that the field is very complex as it is broken into tilted and rotated compartmental blocks by two perpendicular fault systems. Also the 2-D seismic data were of poor quality beneath the thick Miocene South Gharib Evaporite. Since part of the field lies below shallow-water, 3-D seismic was considered to be too costly. When a delineation well did not encounter the reservoir, due to an unanticipated fault, a 2-D walkaway Vertical Seismic Profile (VSP) was acquired. It clearly revealed the presence of a cross fault. The success of the 2-D VSP in imaging the fault led to the acquisition of the first Middle East 3-D VSP survey in the following well. A downhole, tri-axial, five geophone array tool was used to acquire the 3-D VSP. The 3-D volume of the final migrated VSP data provided the means for the reliable mapping of horizons beneath the South Gharib Evaporite. These maps improved the definition of the field and helped detect previously unrecognized prospective blocks. Four further successful delineation wells confirmed the 3-D VSP interpretation.

An integrated surface seismic/seismic profile case study: Simonette area, Alberta

Geophysics ◽  
1993 ◽  
Vol 58 (11) ◽  
pp. 1676-1688
Author(s):  
Ronald C. Hinds ◽  
Neil L. Anderson ◽  
Richard Kuzmiski
Keyword(s):  
Seismic Data ◽  
Cost Effective ◽  
Seismic Profile ◽  
Viable Alternative ◽  
Target Area ◽  
Vertical Seismic Profile ◽  
Subsurface Geology ◽  
Well Location ◽  
Vsp Data

On the basis of conventional surface seismic data, the 13–15–63–25W5M exploratory well was drilled into a low‐relief Leduc Formation reef (Devonian Woodbend Group) in the Simonette area, west‐central Alberta, Canada. The well was expected to intersect the crest of the reef and encounter about 50–60 m of pay; unfortunately it was drilled into a flank position and abandoned. The decision to abandon the well, as opposed to whipstocking in the direction of the reef crest, was made after the acquisition and interpretive processing of both near( and far‐offset (252 and 524 m, respectively) vertical seismic profile (VSP) data, and after the reanalysis of existing surface seismic data. The near‐ and far‐offset VSPs were run and interpreted while the drill rig remained on‐site, with the immediate objectives of: (1) determining an accurate tie between the surface seismic data and the subsurface geology; and (2) mapping relief along the top of the reef over a distance of 150 m from the 13–15 well location in the direction of the adjacent productive 16–16 well (with a view to whipstocking). These surveys proved to be cost‐effective in that the operators were able to determine that the crest of the reef was out of the target area, and that whipstocking was not a viable alternative. The use of VSP surveys in this situation allowed the operators to avoid the costs associated with whipstocking, and to feel confident with their decision to abandon the well.

Dual-well 3D vertical seismic profile enabled by distributed acoustic sensing in deepwater Gulf of Mexico

2015 ◽  
Vol 3 (3) ◽  
pp. SW11-SW25 ◽  
Author(s):  
Han Wu ◽  
Wai-Fan Wong ◽  
Zhaohui Yang ◽  
Peter B. Wills ◽  
Jorge L. Lopez ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Velocity Model ◽  
Seismic Profile ◽  
Seismic Survey ◽  
Vertical Seismic Profile ◽  
Acoustic Sensing ◽  
Velocity Models ◽  
Vsp Data ◽  
Distributed Acoustic Sensing

We have acquired and processed 3D vertical seismic profile (VSP) data recorded simultaneously in two wells using distributed acoustic sensing (DAS) during the acquisition of the 2012 Mars 4D ocean-bottom seismic survey in the deepwater Gulf of Mexico. The objectives of the project were to assess the quality of DAS data recorded in fiber-optic cables from the surface to the total depth, to demonstrate the efficacy of the DAS VSP technology in a deepwater environment, to derisk the use of the technology for future water injection or production monitoring without intervention, and to exploit the velocity information that 3D VSP data provide for evaluating and updating the velocity model. We evaluated the advantages of DAS VSP to reduce costs and intrusiveness, and we determined that high-quality images can be obtained from relatively noisy raw 3D DAS VSP data, as evidenced by the well 1 image, probably the best 3D VSP image we have ever seen. Our results also revealed that the direct arrival traveltimes can be used to assess the quality of an existing velocity model and to invert for an improved velocity model. We identified issues with the DAS acquisition and the processing steps to mitigate them and to handle problems specific to DAS VSP data. We described the steps for conditioning the data before migration, reverse time migration, and postmigration processing to reduce noise artifacts. We outlined a novel first-break picking procedure that works even in the absence of a strong first arrival and a velocity diagnosis method to assess and validate velocity models and velocity updates. Finally, we determined potential applications to 4D monitoring of fluid movement around producer or injector wells, identification of active salt movements, and more accurate imaging and monitoring of complex structures around the wells.

An integrated surface and borehole seismic case study: Fort St. John Graben area, Alberta, Canada

Geophysics ◽  
1993 ◽  
Vol 58 (11) ◽  
pp. 1662-1675
Author(s):  
Ronald C. Hinds ◽  
Richard Kuzmiski ◽  
Neil L. Anderson ◽  
Barry R. Richards
Keyword(s):  
Seismic Data ◽  
Seismic Profile ◽  
Well Log ◽  
Data Set ◽  
Seismic Control ◽  
Subsurface Geology ◽  
Vsp Data ◽  
Borehole Seismic ◽  
Sandstone Facies

The deltaic sandstones of the basal Kiskatinaw Formation (Stoddard Group, upper Mississippian) were preferentially deposited within structural lows in a regime characterized by faulting and structural subsidence. In the Fort St. John Graben area, northwest Alberta, Canada, these sandstone facies can form reservoirs where they are laterally sealed against the flanks of upthrown fault blocks. Exploration for basal Kiskatinaw reservoirs generally entails the acquisition and interpretation of surface seismic data prior to drilling. These data are used to map the grabens in which these sandstones were deposited, and the horst blocks which act as lateral seals. Subsequent to drilling, vertical seismic profile (VSP) surveys can be run. These data supplement the surface seismic and well log control in that: 1) VSP data can be directly correlated to surface seismic data. As a result, the surface seismic control can be accurately tied to the subsurface geology; 2) Multiples, identified on VSP data, can be deconvolved out of the surface seismic data; and 3) The subsurface, in the vicinity of the borehole, is more clearly resolved on the VSP data than on surface seismic control. On the Fort St. John Graben data set incorporated into this paper, faults which are not well resolved on the surface seismic data, are better delineated on VSP data. The interpretive processing of these data illustrate the use of the seismic profiling technique in the search for hydrocarbons in structurally complex areas.

An algebraic reconstruction technique for weakly anisotropic velocity

Geophysics ◽  
1988 ◽  
Vol 53 (12) ◽  
pp. 1613-1615 ◽  
Author(s):  
R. R. Stewart
Keyword(s):  
Seismic Data ◽  
Field Experiments ◽  
Sedimentary Rocks ◽  
Seismic Profile ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Laboratory Measurements ◽  
Vertical Seismic Profile ◽  
Velocity Anisotropy ◽  
Vsp Data

Laboratory measurements and field experiments indicate that many sedimentary rocks display velocity anisotropy (Robertson and Corrigan, 1983; White et al., 1983; Thomsen, 1986; Winterstein, 1986; Gaiser et al., 1987). Accounting for anisotropy is proving important in several areas including the processing and interpretation of shear‐wave data (Lynn and Thomsen, 1986; Bush and Crampin, 1987) and the integration of vertical seismic profile (VSP) data and surface seismic data (Chiu and Stewart, 1987a).

On: “An integrated surface and borehole seismic case study: Fort St. John Graben area, Alberta, Canada,” by R. C. Hinds, R. Kuzminski, N. L. Anderson, and B. R. Richards (November 1993 GEOPHYSICS, 58, p. 1662–1675).

Geophysics ◽  
1994 ◽  
Vol 59 (7) ◽  
pp. 1171-1171
Author(s):  
Miodrag M. Roksandic
Keyword(s):  
Case History ◽  
Seismic Profile ◽  
Interesting Case ◽  
Well Log ◽  
Profile Data ◽  
Vertical Seismic Profile ◽  
Vsp Data ◽  
Integrated Interpretation ◽  
Borehole Seismic

Hinds et al.’s paper is an interesting case history describing the acquisition and interpretive processing of VSP data and presenting an integrated interpretation of well log, surface seismic, and vertical seismic profile data. However, a question of principle arises. What is an integrated interpretation?

Q estimation from vertical seismic profile data and anomalous variations in the central North Sea

Geophysics ◽  
1985 ◽  
Vol 50 (4) ◽  
pp. 615-626 ◽  
Author(s):  
S. D. Stainsby ◽  
M. H. Worthington
Keyword(s):  
North Sea ◽  
Pulse Width ◽  
Spectral Ratio ◽  
Seismic Profile ◽  
Seismic Attenuation ◽  
Recording Equipment ◽  
Vertical Seismic Profile ◽  
High Attenuation ◽  
Vsp Data ◽  
Central North Sea

Four different methods of estimating Q from vertical seismic profile (VSP) data based on measurements of spectral ratios, pulse amplitude, pulse width, and zeroth lag autocorrelation of the attenuated impulse are described. The last procedure is referred to as the pulse‐power method. Practical problems concerning nonlinearity in the estimating procedures, uncertainties in the gain setting of the recording equipment, and the influence of structure are considered in detail. VSP data recorded in a well in the central North Sea were processed to obtain estimates of seismic attenuation. These data revealed a zone of high attenuation from approximately 4 900 ft to [Formula: see text] ft with a value of [Formula: see text] Results of the spectral‐ratio analysis show that the data conform to a linear constant Q model. In addition, since the pulse‐width measurement is dependent upon the dispersive model adopted, it is shown that a nondispersive model cannot possibly provide a match to the real data. No unambiguous evidence is presented that explains the cause of this low Q zone. However, it is tentatively concluded that the seismic attenuation may be associated with the degree of compaction of the sediments and the presence of deabsorbed gases.

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