Full‐waveform processing and interpretation of kilohertz cross‐well seismic data

Geophysics ◽  
1993 ◽  
Vol 58 (9) ◽  
pp. 1248-1256 ◽  
Author(s):  
Ashraf A. Khalil ◽  
Robert R. Stewart ◽  
David C. Henley
Keyword(s):  
Oil Recovery ◽  
Seismic Data ◽  
Shear Waves ◽  
Synthetic Seismograms ◽  
Oil Field ◽  
S Wave ◽  
Sonic Log ◽  
The Cross ◽  
Interval Velocities ◽  
The Individual

High‐frequency, cross‐well seismic data, from the Midale oil field of southeastern Saskatchewan, are analyzed for direct and reflected energy. The goal of the analysis is to produce interpretable sections to assist in enhanced oil recovery activities ([Formula: see text] injection) in this field. Direct arrivals are used for velocity information while reflected arrivals are processed into a reflection image. Raw field data show a complex assortment of wave types that includes direct compressional and shear waves and reflected shear waves. A traveltime inversion technique (layer stripping via ray tracing) is used to obtain P‐ and S‐wave interval velocities from the respective direct arrivals. The velocities from the cross‐well inversion and the sonic log are in reasonable agreement. The subsurface coverage of the cross‐well geometry is investigated; it covers zones extending from the source well to the receiver well and includes regions above and below the source/receiver depths. Upgoing and downgoing primary reflections are processed, in a manner similar to the vertical seismic profiling/common‐depth‐point (VSP/CDP) map, to construct the cross‐well images. A final section is produced by summing the individual reflection images from each receiver‐gather map. This section provides an image with evidence of strata thicknesses down to about 1 m. Synthetic seismograms are used to interpret the final sections. Correlations can be drawn between some of the events on the synthetic seismograms and the cross‐well image.

scholarly journals Anisotropy extraction using a deviated well in the Mahanadi Basin, East Coast of India

2019 ◽  
Vol 10 (3) ◽  
pp. 911-918
Author(s):  
Biplab Kumar Mukherjee ◽  
G. Karthikeyan ◽  
Karanpal Rawat ◽  
Hari Srivastava
Keyword(s):  
Seismic Data ◽  
East Coast ◽  
Velocity Model ◽  
P Wave ◽  
S Wave ◽  
Gardner Equation ◽  
East Coast Of India ◽  
Nonlinear Fitting ◽  
Sonic Log ◽  
Mahanadi Basin

Abstract Shale is the primary rock type in the shallow marine section of the Mahanadi Basin, East Coast of India. Shale, being intrinsically anisotropic, always affects the seismic data. Anisotropy derived from seismic and VSP has lower resolution and mostly based on P wave. The workflow discussed here uses Gardner equation to derive vertical velocity and uses a nonlinear fitting to extract the Thomsen’s parameters using both the P wave and S wave data. These parameters are used to correct the sonic log of a deviated well as well as anisotropic AVO response of the reservoir. The presence of negative delta was observed, which is believed to be affected by the presence of chloride and illite in the rock matrix. This correction can be used to update the velocity model for time–depth conversion and pore pressure modelling.

scholarly journals 2D Seismic Structural and Stratigraphic Study of Kirkuk Group Formation in Amara Oil Field- Southeastern Iraq

2021 ◽  
pp. 3942-3951
Author(s):  
Ali K. Jaheed ◽  
Hussein H. Karim
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Sedimentary Basin ◽  
Group Formation ◽  
Structural Features ◽  
Field Structure ◽  
Synthetic Seismograms ◽  
Oil Field ◽  
Well Logs ◽  
Depth Maps

The Amarah Oil field structure was studied and interpreted by using 2-D seismic data obtained from the Oil  Exploration company. The study is concerned with Maysan Group Formation (Kirkuk Group) which is located in southeastern Iraq and belongs to the Tertiary Age. Two reflectors were detected based on synthetic seismograms and well logs (top and bottom Missan Group). Structural maps were derived from seismic reflection interpretations to obtain the location and direction of the sedimentary basin. Two-way time and depth maps were conducted depending on the structural interpretation of the picked reflectors to show several structural features. These included three types of closures, namely two anticlines extended in the directions of S-SW and NE, one nose structure (anticline) in the middle of the study area,  and structural faults in the northeastern part of the area, which is consistent with the general fault pattern. The seismic interpretation showed the presence of some stratigraphic features. Stratigraphic trap at the eastern part of the field, along with other phenomena, such as flatspot (mound), lenses, onlap, and toplap, were detected as indications of potential hydrocarbon accumulation in the region.

Interface prediction ahead of the excavation front by the tunnel-seismic-while-drilling (TSWD) method

Geophysics ◽  
2007 ◽  
Vol 72 (4) ◽  
pp. G39-G44 ◽  
Author(s):  
Lorenzo Petronio ◽  
Flavio Poletto ◽  
Andrea Schleifer
Keyword(s):  
Seismic Data ◽  
Reference Signal ◽  
Tunnel Boring Machine ◽  
S Wave ◽  
Tunnel Boring ◽  
Vertical Seismic Profiling ◽  
Mechanical Excavation ◽  
Seismic Sensors ◽  
Interface Prediction ◽  
Interval Velocities

Predicting geologic interfaces ahead of a tunnel front is of major importance when boring tunnels. Unexpected variations in ground properties can cause problems for tunnel-boring advance and risk for human safety. The tunnel-seismic-while-drilling (TSWD) method utilizes noise produced during mechanical excavation to obtain interpretable seismic data. This passive method uses accelerometers mounted on the advancing tunnel-boring machine (reference signals) together with seismic sensors located along and outside the tunnel. Data recorded by fixed sensors are crosscorrelated with the reference signal and sorted by offset. Similar to reverse vertical seismic profiling, crosscorrelated TSWD data are processed to extract the reflected wavefield. During mechanical excavation of a [Formula: see text] tunnel through upper Triassic dolomite, a survey was performed to predict geologic interfaces. Faults intersecting the tunnel were observed on seismic TSWD data and later were confirmed by geostructural inspection. P- and S-wave interval velocities obtained by TSWD data along the bored tunnel were used to compute dynamic rock moduli to support tunnel completion.

Nonlinear pairwise alignment of seismic traces

Geophysics ◽  
2004 ◽  
Vol 69 (6) ◽  
pp. 1552-1559 ◽  
Author(s):  
Christopher L. Liner ◽  
Robert G. Clapp
Keyword(s):  
Seismic Data ◽  
Field Data ◽  
Pairwise Alignment ◽  
Optimization Method ◽  
Synthetic Seismograms ◽  
Amino Acid Sequences ◽  
Global Alignment ◽  
Global Optimization Method ◽  
S Wave ◽  
Alignment Problem

Seismic trace alignment is a recurring need in seismic processing and interpretation. For global alignment via static shift, there are robust tools available, including crosscorrelation. However, another kind of alignment problem arises in applications as diverse as associating synthetic seismograms to field data, harmonizing P‐ and S‐wave data, residual NMO, and final multilevel flattening of common image gathers. These cases require combinations of trace compression, extension, and shift—all of which are time variant. The difficulty is to find a mapping between the traces that is in some senseoptimum. This problem is solved here using a modified form of the Needleman‐Wunsch algorithm, a global optimization method originally developed for aligning amino acid sequences in proteins. Applied to seismic traces, this algorithm provides a nonlinear mapping of one seismic trace onto another. The method extends to multitrace alignment since that problem can be broken down into a cascade of pairwise alignments. Seismic implementation of the Needleman‐Wunsch algorithm is a promising new tool for nonlinear alignment and flattening of seismic data.

A case study showing the value of multioffset synthetic seismograms in seismic data interpretation

2016 ◽  
Vol 4 (4) ◽  
pp. T455-T459 ◽  
Author(s):  
J. Helen Isaac ◽  
Don C. Lawton
Keyword(s):  
Seismic Data ◽  
Upper Cretaceous ◽  
Normal Incidence ◽  
High Amplitude ◽  
Synthetic Seismogram ◽  
Synthetic Seismograms ◽  
Seismic Survey ◽  
Research Station ◽  
S Wave ◽  
Low Amplitude

A baseline 3D3C seismic survey was acquired in May 2014 at a Field Research Station in Southern Alberta, Canada, which is the site of experimental [Formula: see text] injection into an Upper Cretaceous sandstone at approximately 300 m depth. We have created synthetic seismograms from sonic and density logs to identify reflectors seen on the processed seismic data. The high-amplitude positive response (peak) at the top of the Upper Cretaceous Milk River Formation sandstone on the normal incidence PP synthetic seismogram does not match the response seen on the migrated PP seismic data, which is a very low amplitude peak. For such a high impedance, low Poisson’s ratio sandstone, the Zoeppritz equations predict a high-amplitude reflection coefficient at zero offset, then a decrease in amplitude, and even a change in polarity with increasing source-receiver offset. To match the stacked seismic data better, we have created offset synthetic seismograms using P- and S-wave sonic logs and density logs. The character of the top Milk River reflection on the seismic data stacked using all offset traces resembles that observed on the stacked offset synthetic seismogram, which is a similar low-amplitude peak. The character of the top Milk River reflection on the seismic data stacked using only near-offset traces to 250 m looks like that seen on the normal incidence synthetic seismogram.

Seismicity in the Rangely, Colorado, area: 1962-1970

1973 ◽  
Vol 63 (5) ◽  
pp. 1557-1570 ◽  
Author(s):  
James F. Gibbs ◽  
John H. Healy ◽  
C. Barry Raleigh ◽  
John Coakley
Keyword(s):  
Seismic Data ◽  
Water Injection ◽  
Seismic Energy ◽  
Seismic Signal ◽  
Oil Field ◽  
P Wave ◽  
S Wave ◽  
Uinta Basin ◽  
Wave Measurements

abstract Seismic data recorded for a 7-year period at the Uinta Basin Observatory were searched for earthquakes originating near an oil field at Rangely, Colorado, 65 km ESE of the observatory. Changes in the number of earthquakes recorded per year appear to correlate with changes in the quantity of fluid injected per year. Between November 1962 and January 1970, 976 earthquakes were detected near the oil field by the UBO station; 320 earthquakes were larger than magnitude 1. Richter local magnitudes are estimated from both S-wave and P-wave measurements; a method based on the duration of the seismic signal is used to estimate the magnitude of the larger shocks. Magnitude of the two largest shocks was 3.4 and 3.3. The total seismic energy released was 1017 ergs. During this same period, the energy used for water injection, measured at the wellhead, was 1021 ergs.

Anisotropy effects in P-wave and SH-wave stacking velocities contain information on lithology

Geophysics ◽  
1986 ◽  
Vol 51 (3) ◽  
pp. 661-672 ◽  
Author(s):  
D. F. Winterstein
Keyword(s):  
Seismic Data ◽  
P Wave ◽  
Sh Wave ◽  
S Wave ◽  
Velocity Anisotropy ◽  
Midland Basin ◽  
Wave Data ◽  
Event Times ◽  
Interval Velocities ◽  
Constituent Layer

Depths calculated from S-wave stacking velocities and event times almost always exceed actual depths, sometimes by as much as 25 percent. In contrast, depths from corresponding P-wave information are often within 10 percent of actual depths. Discrepancies in depths calculated from P- and S-wave data are attributed to velocity anisotropy, a property of sedimentary rocks that noticeably affects S-wave moveout curves but leaves the P-wave relatively unaffected. Two careful studies show that discrepancies in depths, and hence in constituent layer thicknesses, correlate with lithology. Discrepancies ranged from an average of 13 percent (Midland basin) to greater than 40 percent (Paloma field) in shales, but were within expected errors in massive sandstones or carbonates. Hence anisotropy effects are indicators of lithology. Analysis of seismic data involved determining interval velocities from stacking velocities, calculating layer thicknesses, and then comparing layer thicknesses from S-wave data with thicknesses from P-wave data. When the S-wave thicknesses were significantly greater than the P-wave (i.e., outside the range of expected errors), I concluded the layer was anisotropic. I illustrate the technique with data from the Paloma field project of the Conoco Shear Wave Group Shoot.

VTI documented

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 237-245 ◽  
Author(s):  
D. F. Winterstein ◽  
G. S. De
Keyword(s):  
Seismic Data ◽  
Transversely Isotropic ◽  
Seismic Profile ◽  
Oil Field ◽  
Central Basin ◽  
S Wave ◽  
West Texas ◽  
Wave Splitting ◽  
Vertical Propagation ◽  
Central Basin Platform

Shear‐wave (S‐wave) seismic data indicate that rocks of McElroy oil field on the Central Basin Platform of West Texas are transversely isotropic with a vertical symmetry axis (VTI). Although geophysicists from time to time had anticipated or assumed that sedimentary rock was VTI, no one had shown that any sedimentary section actually was VTI. The proof at McElroy comes from a nine‐component, near‐offset vertical seismic profile (VSP) combined with a ring of 15 offset VSPs spaced about 24° apart at offsets of about 460 m. S-wave splitting at VSP frequencies was negligible for vertical propagation to a depth of 885 m but reached about 12 ms for nonvertical propagation from the offset source locations. Crossed‐dipole log data supported the VSP result for vertical propagation but found two layers of vertically birefringent rock at depth whose thicknesses were below VSP resolution.

scholarly journals Insights to enhance the examination of tool marks in human cartilage

2021 ◽  
Author(s):  
Matthias Weber ◽  
Anja Niehoff ◽  
Markus A. Rothschild
Keyword(s):  
Light Microscope ◽  
Cross Correlation ◽  
Costal Cartilage ◽  
Correlation Coefficients ◽  
Human Cartilage ◽  
Cut Marks ◽  
Tool Marks ◽  
The Cross ◽  
Cleaning Methods ◽  
The Individual

AbstractThis work deals with the examination of tool marks in human cartilage. We compared the effectiveness of several cleaning methods on cut marks in porcine cartilage. The method cleaning by multiple casts achieved the significantly highest scores (P = 0.02). Furthermore, we examined the grain-like elevations (dots) located on casts of cut cartilage. The results of this study suggest that the casting material forms these dots when penetrating cartilage cavities, which are areas where the strong collagen fibres leave space for the chondrocytes. We performed fixation experiments to avoid this, without success. In addition, 31 casting materials were compared regarding contrast under light-microscope and 3D tool marks scanner. Under the light-microscope, brown materials achieved significantly higher values than grey (P = 0.02) or black (P = 0.00) whereas under the 3D scanner, black materials reached higher contrast values than grey (P = 0.04) or brown (P = 0.047). To compare the accuracy and reproducibility of 6 test materials for cartilage, we used 10 knives to create cut marks that were subsequently scanned. During the alignment of the individual signals of each mark, the cross-correlation coefficients (Xmax) and lags (LXmax) were calculated. The signals of the marks in agarose were aligned with significantly fewer lags and achieved significantly higher cross-correlation coefficients compared to all tested materials (both P = 0.00). Moreover, we determined the cross-correlation coefficients (XC) for known-matches (KM) per material. Agarose achieved significantly higher values than AccuTrans®, Clear Ballistics™, and gelatine (all P = 0.00). The results of this work provide valuable insights for the forensic investigation of marks in human costal cartilage.

scholarly journals Design Approach for Reducing Cross-Axis Sensitivity in a Single-Drive Multi-Axis MEMS Gyroscope

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 902
Author(s):  
Hussamud Din ◽  
Faisal Iqbal ◽  
Byeungleul Lee
Keyword(s):  
Microelectromechanical Systems ◽  
Reduction Rate ◽  
Design Technique ◽  
Matching Method ◽  
Mems Gyroscope ◽  
Mode Split ◽  
The Cross ◽  
The Individual ◽  
Cross Axis ◽  
Ratio Matching

In this paper, a new design technique is presented to estimate and reduce the cross-axis sensitivity (CAS) in a single-drive multi-axis microelectromechanical systems (MEMS) gyroscope. A simplified single-drive multi-axis MEMS gyroscope, based on a mode-split approach, was analyzed for cross-axis sensitivity using COMSOL Multiphysics. A design technique named the “ratio-matching method” of drive displacement amplitudes and sense frequency differences ratios was proposed to reduce the cross-axis sensitivity. Initially, the cross-axis sensitivities in the designed gyroscope for x and y-axis were calculated to be 0.482% and 0.120%, respectively, having an average CAS of 0.301%. Using the proposed ratio-matching method and design technique, the individual cross-axis sensitivities in the designed gyroscope for x and y-axis were reduced to 0.018% and 0.073%, respectively. While the average CAS was reduced to 0.045%, showing a reduction rate of 85.1%. Moreover, the proposed ratio-matching method for cross-axis sensitivity reduction was successfully validated through simulations by varying the coupling spring position and sense frequency difference variation analyses. Furthermore, the proposed methodology was verified experimentally using fabricated single-drive multi-axis gyroscope.

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