ACM/DAB/O:Reports/Processing/S6144/939 © TESLA-IMC International Limited Teck Ireland February 2011
REPORT
on
2D SEISMIC PROCESSING AT BALLINALACK
for
TECK IRELAND LIMITED
by
TESLA-IMC INTERNATIONAL LIMITED
FEBRUARY 2011
Prepared by: S Ali Approved by:
TESLA-IMC International Limited Unit 2 Nix’s Hill
Nix’s Hill Industrial Estate
Alfreton Derbyshire
DE55 7GN
Telephone: 01773 838950
Facsimile: 01773 836492
email: [email protected]
All geophysical work carried out by TESLA-IMC International is based on long experience and
well founded expectation that it will prove beneficial to the client. However, TESLA-IMC
International can accept no liability for consequential loss of any kind resulting from the
interpretation of geophysical data.
ACM/DAB/O:Reports/Processing/S6144/939 2 © TESLA-IMC International Limited
Teck Ireland February 2011
CONTENTS
Page No
LIST OF ILLUSTRATIONS ...................................................................................... 3
1.0 INTRODUCTION ............................................................................................ 4
2.0 SEISMIC LINE ACQUISITION SUMMARY................................................ 5
3.0 PROCESSING SUMMARY ............................................................................ 6
3.1 Processing Sequence for Post Stack Time Migration ............................. 6
3.2 Processing Sequence for Pre-Stack Time Migration .............................. 7
4.0 DISCUSSION OF BASIC PROCESSING PARAMETERS .......................... 7
4.1 Pre-stack Processes .................................................................................. 7
4.2 Post Stack Processes ................................................................................ 9
5.0 SUMMARY OF PROCESSING STAGES AND CONCLUSIONS ............. 10
6.0 PERSONNEL................................................................................................. 11
7.0 DISTRIBUTION ............................................................................................ 11
APPENDIX A CD Listing
ACM/DAB/O:Reports/Processing/S6144/939 3 © TESLA-IMC International Limited
Teck Ireland February 2011
LIST OF ILLUSTRATIONS
Table
1. Summary of Acquisition Parameters
Figures (Power Point Slides)
1. Elevation Statics Stack without Pre-processing
2. 3D Refraction Statics Model (Receiver Domain) Elevations
3. 3D Refraction Statics Model (Shot Domain) Elevations
4. 3D Refraction Statics Model (Receiver Domain) Statics
5. 3D Refraction Statics Model (Shot Domain) Statics
6. Refraction Statics Stack without Pre-processing
7. Refraction Statics Stack with Pre-processing
8. Refraction Statics Stack with First Velocity Analysis
9. First Residual Statics Stack with Second Velocity Analysis
10. Second Residual Statics Stack
11. Final Stack with Trim Statics
12. Filter Test
13. Final Filtered Stack
14. Post Stack Time Migrated Stack (Filtered)
15. Pre-stack Time Migrated Stack (Filtered)
16. Line TK-10-01 Raw Shot Record with sweep length 28 seconds
17. Line TK-10-02 Raw Shot Record with sweep length 14 seconds
Enclosure
1. CDP location map Scale 1:25,000
ACM/DAB/O:Reports/Processing/S6144/939 4 © TESLA-IMC International Limited
Teck Ireland February 2011
1.0 INTRODUCTION
Two lines totalling 4.7km of 2D seismic data were processed by TESLA-IMC International
Ltd using Landmark ProMAX V2003.19.1 processing software and Green Mountain
Geophysics (GMG) Millennium Suite refraction statics software. Processing was carried out
at the TESLA-IMC International processing centre at Alfreton, Derbyshire in the UK.
This project included the processing of two lines, which were acquired by TESLA-IMC in
May 2010, using a vibroseis energy source. These lines were regarded as test lines to
determine optimum acquisition and processing parameters.
The parameter details for this project are given in the Acquisition Summary of this report (see
Table 1).
Data quality of line 01 was much better than line 02. An important difference in the
acquisition parameters was the 28 second sweep length on line 01 compared with 14 second
sweep length on line 02, as well as the 5m group interval on line 01 compared with 10m
interval on line 02. Maximum trace fold on line 01 was 300 and 90 on line 02. Line 01 was
also recorded cross country whereas line 02 was on a main road with traffic noise. Figures 16
and 17 are screen dumps of the raw shot records of each line, illustrating the difference in the
data quality.
The lines were processed to a datum of 50m above Mean Sea Level using a one layer, pseudo
3D refraction statics model. The lines were processed in SEG polarity, minimum phase and
the data processing was supervised by A C Mann of TESLA-IMC.
The coordinate system used in processing was Irish National Grid TM65.
ACM/DAB/O:Reports/Processing/S6144/939 5 © TESLA-IMC International Limited Teck Ireland February 2011
2.0 SEISMIC LINE ACQUISITION SUMMARY
Table 1
Summary of Acquisition Parameters
Line No.
Recv
Total
FFID
min
CDP
max
CDP
Total
CDP
Source
int (m)
Receiver
int (m)
CDP
int
(m)
No.
Chan
Xmin
(m)
Source
Sweep
(Hz)
Sweep
Length
(s)
Dt
(ms)
Record
length
(s)
CDP
Line Length
(km)
TK-10-01 403 151 2 332 331 5 5 2.5 403 2.5 Vibroseis 28 1 2.0 0.825
20-140
TK-10-02 424 189 3 778 776 20 10 5 300 5 Vibroseis 14 1 2.0 3.875
20-140
Total CDP line length (km) = 4.70
ACM/DAB/O:Reports/Processing/S6144/939 6 © TESLA-IMC International Limited Teck Ireland February 2011
3.0 PROCESSING SUMMARY
3.1 Processing Sequence for Post Stack Time Migration
Transcription from SEG Y to ProMAX internal format
2D CDP crooked line binning
Geometry Assignment
Trace edit – Editing of bad traces
First Break Picking
True Amplitude Recovery, using 6dB/sec correction
Surface Wave Noise Attenuation (Receiver and Source domains), using a velocity of
2000m/s
Linear Noise Attenuation using a velocity of 340 m/s
Bandpass Filter
Deconvolution (Predictive, minimum phase) – Standard deconvolution, operator
length 80ms and prediction distance (gap) of 20ms
Pseudo 3D Refraction Statics Analysis and application to final datum elevation of
50m above Mean Sea Level, using a one layer solution and a replacement velocity of
2000 m/s
First interactive Velocity analysis, at least every 500m
Residual Statics Correction - Maximum Power algorithm, maximum static allowed
+/- 10ms
Second interactive velocity analysis, at least every 250m
Residual Statics correction (Second Pass) – Maximum Power, maximum static
allowed +/- 10ms
First mis-tie QC using Kingdom interpretation software
Normal Moveout correction – Using Final stacking velocities
Residual Statics (3rd
pass), non surface consistent (Trim Statics)
Mute – selection and application of final top mute
CDP Stack
Second mis-tie QC using Kingdom interpretation software
FX Deconvolution – Random noise attenuation
Finite Difference Time Migration using 45 dip and averaged interval velocities
derived from smoothed final stacking velocities
Time Variant Bandpass Filtering
Final Scaling - AGC applied using a gate length of 300ms
ACM/DAB/O:Reports/Processing/S6144/939 7 © TESLA-IMC International Limited Teck Ireland February 2011
3.2 Processing Sequence for Pre-Stack Time Migration
Input Second pass Residual Statics applied data
Common offset binning
Pre-stack Kirchhoff Time Migration
Third Interactive Velocity analysis, at least every 250m
Normal Moveout correction - Using Final Stacking Velocities
Mute selection and application of final top mute
CDP Stack
FX Deconvolution - Random noise attenuation
Time Variant Bandpass filtering
Final Scaling – AGC applied using a gate length of 300ms
4.0 DISCUSSION OF BASIC PROCESSING PARAMETERS
4.1 Pre-stack Processes
The following pre-stack processing was applied to the data:
Transcription from SEG Y to internal ProMAX format.
The original raw data provided for all lines were in SEG Y format, which were subsequently
converted to ProMAX internal format for processing. During this stage the raw shot records
were displayed on screen to enable a QC of the raw data. This consisted of:
1. Identification of missing shot records
2. Identification of bad shot records
3. Identification of any repeated FFID’s (Field File Identification Number)
4. Assessing the total number of channels
5. Removal of auxiliary traces
6. Assessing record length
7. Assessing data polarity
Geometry Assignment / Installation
ProMAX geometry database files were created using the information obtained from provided
survey/observer logs. Information loaded into the trace headers includes:
1. Group Interval
2. Shot Interval
3. Shot Point Range
4. Receiver Range
5. FFID Range
6. Gap Size
7. Number of channels
8. Minimum / maximum offset
9. Navigation (both for Source and Receiver)
10. Spread Type
ACM/DAB/O:Reports/Processing/S6144/939 8 © TESLA-IMC International Limited Teck Ireland February 2011
The raw data, observers logs and navigation data were provided by the TESLA-IMC field
crew.
Trace Edit
Each shot was displayed on screen and any appropriate bad traces were edited.
True Amplitude Recovery (TAR)
Tests were carried out for TAR including; dB/sec, Time raised to a power and spherical
divergence correction. After a comparison of results, 6dB/sec correction was used.
Surface Wave Noise Attenuation using a velocity of 2000 m/s was applied both in shot
and receiver domains. Also we applied a second pass of linear noise attenuation, using a
velocity of 340 m/s.
Deconvolution
After testing Predictive Deconvolution (Minimum Phase) was applied using an operator
length of 80ms and prediction distance of 20ms.
3D Refraction Static corrections and application:
Static corrections were applied to the seismic data to compensate for the effects of
variations in elevation, weathering thickness, weathering velocity and reference to a
processing datum. The GMG Millennium Suite Refraction Statics software was used for
calculating and output of pseudo 3D static solutions, for input into each ProMAX seismic
line database. Correction to a final datum of 50m above Mean Sea Level was carried out
using a replacement velocity of 2000 m/s.
First Interactive Velocity Analysis
Velocities were interactively picked using the ProMAX Velocity Analysis module,
consisting of a Semblance, NMO-animated super gather (11 CDP’s), dynamic stack
panel, stack panels and an interval velocity graph. The first velocity analysis was carried
out at least every 500m.
Residual Statics Correction (First Pass) using Maximum Power Autostatics
Surface consistent residual autostatics were run with one gate. The gate was 500ms wide,
centred at around 500ms. The pilot trace smash was 11 CDPs and the maximum static
allowed was +/- 10ms.
Second Interactive Velocity Analysis
Velocities were interactively picked using the ProMAX Velocity Analysis module and
were located at least every 250m.
Residual Statics Correction (Second Pass) using Maximum Power Autostatics
Surface consistent residual autostatics were run with one gate. The gate was 500ms wide,
centred at around 500ms. The pilot trace smash was 11 CDPs and the maximum static
allowed was +/- 10ms.
Common Offset DMO
DMO (Dip moveout) was tested but it degraded the stack, therefore, was not included in
the sequence.
ACM/DAB/O:Reports/Processing/S6144/939 9 © TESLA-IMC International Limited Teck Ireland February 2011
Normal Moveout Correction
NMO was applied using the Final Stacking Velocities.
Top Mute Application
A final Top Mute was interactively picked on NMO corrected CDP gathers to remove the
first breaks and the NMO stretch.
CDP Stack
The data was sorted in CDP domain, stacked and shifted to the final datum.
4.2 Post Stack Processes
FX Deconvolution
FX Deconvolution was tested and applied to the data to reduce the residual random noise
in the stack data.
Post Stack Time Migration
Finite Difference (Implicit) Post Stack Time Migration was run on each line. The velocity
functions were derived from the stacking velocities, which were first smoothed and then
converted to interval velocities and averaged (single function). The migration velocities
were scaled down if necessary for better imaging. The maximum angle of dip to migrate
was 45 degrees.
Time Variant Bandpass Filter
Bandpass filter tests were carried out on line TK-10-01. The time variant bandpass filter
was chosen and applied to all lines as follows:
Final Scaling
After testing, an AGC using a gate length of 300ms was chosen and applied to the data.
TWT (ms) Frequency (Hz)
0-200 25-30-90-100
300-900 20-25-70-80
1000-2000 20-25-50-60
ACM/DAB/O:Reports/Processing/S6144/939 10 © TESLA-IMC International Limited Teck Ireland February 2011
5.0 SUMMARY OF PROCESSING STAGES AND CONCLUSIONS
Ten significant processing stages on line TK-10-01 are illustrated and these examples show
the gradual enhancement of the primary reflection data through increasing processing effort.
Stage 1 (Figure 1): Elevations Statics stack without pre-processing applied.
Stage 2 (Figure 6): Refraction Statics stack without pre-processing applied.
Stage 3 (Figure 7): Refraction Statics stack with pre-processing applied.
Stage 4 (Figure 8): Refraction Statics stack with First Velocity Analysis.
Stage 5 (Figure 9): First Residual Statics stack after Second Velocity Analysis.
Stage 6 (Figure 10): Second Residual Statics stack.
Stage 7 (Figure 11): Final Stack with Trim Statics.
Stage 8 (Figure 12): Bandpass filter test.
Stage 9 (Figure 13): Final Filtered Stack with the application of final bandpass filters and
scaling.
Stage 10 (Figure 14): Post Stack Finite Difference Time Migration.
The GMG refraction statics solution improved reflection continuity by removing surface
static anomalies, which were not previously fully resolved by elevation statics. The
combination of interactive velocity picking, first and second applications of Surface
Consistent Autostatics (Residual Statics) greatly improved the resolution of the data. The
static adjustments were small in both cases, making small improvements in reflection
continuity within the well constrained autostatics solution. The data were found to be very
velocity sensitive.
Finite Difference Time Migration was applied post stack. A single migration velocity
(interval) function was calculated for each line.
Post stack FX Deconvolution was applied to the data; this reduced swinging artefacts
generated from residual noise.
Pre-stack time migration tests showed better results on line 01 with better data quality than
line 02.
ACM/DAB/O:Reports/Processing/S6144/939 11 © TESLA-IMC International Limited Teck Ireland February 2011
6.0 PERSONNEL
The following processing personnel worked on this project,
M M Ali – Senior Seismic Processor
S Ali – Seismic Processor
R Goodwin – Seismic Processor
Phil Eaton – Geologist (first break picking)
7.0 DISTRIBUTION
Teck Ireland Ltd (2 copies)
TESLA-IMC International Archive (1 copy)
APPENDIX A
APPENDIX A
CD Listing
1. Processing Report.pdf
2. PowerPoint slides (Report Figures)
3. ASCII CDP X and Y
Source X and Y
Receiver X and Y
4. SEG Y: Filtered Stacks
5. SEG Y: Post Stack Time Migrated Stacks
6. SEG Y: Pre- stack Time Migrated Stacks
!( 50
!( 100
!( 150
!( 200
!( 250
!( 300
!( 2
!( 332
!( 50
!( 100
!( 150
!( 200
!( 250
!( 300
!( 350
!( 400
!( 450
!( 500
!( 550
!( 600
!( 650
!( 700
!( 750
!( 3
!( 778
TK-10-02
TK-10-01
TK-10-02
TK-10-01
232000
232000
233000
233000
234000
234000
235000
235000
236000
236000
26500
0
26500
0
26600
0
26600
0
26700
0
26700
0
±1:10,000
@ A2
0.1 0 0.1 0.2 0.3 0.4 0.5 0.60.05
Kilometers
0.1 0 0.1 0.20.05
Miles
Coordinate System: TM65 Irish GridProjection: Transverse Mercator
Datum: TM65False Easting: 200,000.000000
False Northing: 250,000.000000Central Meridian: -8.000000
Scale Factor: 1.000035Latitude Of Origin: 53.500000
Units: Meter
Teck IrelandBallinalack
CDP Location Map Key:
Date: 08/02/2011 Reference: Processing report
D:\ARCGIS\Seismic\teck\ballinalack\ballinalack.mxd
None required.
Figure 1 : Elevation Statics Stack without Pre-processing
Line TK-10-01
Figure 2: 3D Refraction Statics Model (Receiver Domain) Elevations
Figure 3 : 3D Refraction Statics Model (Shot Domain) Elevations
Figure 4 : 3D Refraction Statics Model (Receiver Domain) Statics
Figure 5 : 3D Refraction Statics Model (Shot Domain) Statics
Figure 6 : Refraction Statics Stack without Pre-processing
Line TK-10-01
Figure 7 : Refraction Statics Stack with Pre-processing
Line TK-10-01
Figure 8 : Refraction Statics Stack with First Velocity Analysis
Line TK-10-01
Figure 9 : First Residual Statics Stack with Second Velocity Analysis
Line TK-10-01
Figure 10 : Second Residual Statics Stack
Line TK-10-01
Figure 11 : Final Stack with Trim Statics
Line TK-10-01
Figure 12 : FILTER Test – CDP Range 91-190
Line TK-10-01
Figure 13 : Final Filtered Stack
Line TK-10-01
Figure 14 : Post Stack Time Migrated Stack (Filtered)
Line TK-10-01
Figure 15 : Pre-Stack Time Migrated Stack (Filtered)
Line TK-10-01
Figure 16 : Line-01, RAW SHOT Record with Sweep Length 28 seconds
Line TK-10-01
Line TK-10-02
Figure 17 : Line-02, RAW SHOT Record with Sweep Length 14 seconds
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