REPORT on 2D SEISMIC PROCESSING AT BALLINALACK for TECK...

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.

mailto:[email protected]

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



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



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


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


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


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.


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


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.


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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