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Velocity Analysis and Depth Conversion in the Offshore Northern Perth Basin

The northern Perth Basin is an elongate sedimentary basin, located off the southwestern margin of Australia. The basin is prospective for petroleum resources, but is relatively under-explored, and the nature of the sediment-basement contact is relatively unknown due to a high degree of structuring and deep basement depth inhibiting seismic imagining. Accurate depth conversion of seismic interpretation is vital for use as constraints in gravity modelling and in other basin modelling tasks, but depth conversion requires good quality seismic velocity information. The number and distribution of wells with velocity information in the northern Perth Basin is poor, but there exists a large amount of seismic stacking velocities. Seismic stacking velocities are an outcome of seismic processing and are thus not a direct measurement of the speed of sound in rocks. To improve the quality of stacking velocities we propose a methodology to calibrate stacking velocities against well velocities, which is as follows:


1. Check each velocity dataset for errors

2. Modify the datum of each dataset to the sea floor

3. Convert all datasets to TWT and depth domain

4. Resample all velocity datasets to the same depth intervals

5. Cross plot stacking velocity depths near a well site with corresponding well depths

6. Fit a linear polynomial to this cross-plot (higher order polynomials were tried also), and determine calibration coefficient from the gradient of the polynomial.

7. Grid calibration coefficients

8. Multiply depths derived from stacking velocities by calibration coefficient grid


An assessment of depth conversion errors relative to wells shows that this methodology improves depth conversion results to within ±50m; this depth uncertainty translates into a gravity anomaly error of about ±20 gu, which is acceptable for regional scale gravity modelling.

Simple

Identification info

Date (Publication)
2011-01-01T00:00:00
Citation identifier
Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/73001

Cited responsible party
Role Organisation / Individual Name Details
Publisher

Geoscience Australia

Canberra
Author

Johnston, S.W.

1
Author

Goncharov, A.

2
Name

Record

Issue identification

2012/033

Point of contact
Role Organisation / Individual Name Details
Custodian

ED

Owner

Commonwealth of Australia (Geoscience Australia)

Custodian

Commonwealth of Australia (Geoscience Australia)

Voice
Topic category
  • Geoscientific information

Extent

N
S
E
W


Maintenance and update frequency
Unknown

Resource format

Title

Product data repository: Various Formats

Website

Data Store directory containing the digital product files

Data Store directory containing one or more files, possibly in a variety of formats, accessible to Geoscience Australia staff only for internal purposes

Keywords
  • GA Publication

  • Record

Theme
  • seismic velocity

Theme
  • marine

Keywords
  • AU-WA

Australian and New Zealand Standard Research Classification (ANZSRC)
  • Earth Sciences

Keywords
  • Published_External

Resource constraints

Title

Creative Commons Attribution 4.0 International Licence

Alternate title

CC-BY

Edition

4.0

Website

http://creativecommons.org/licenses/

Access constraints
License
Use constraints
License

Resource constraints

Title

Australian Government Security ClassificationSystem

Edition date
2018-11-01T00:00:00
Website

https://www.protectivesecurity.gov.au/Pages/default.aspx

Classification
Unclassified
Language
English
Character encoding
UTF8

Distribution Information

Distributor contact
Role Organisation / Individual Name Details
Distributor

Commonwealth of Australia (Geoscience Australia)

Voice
OnLine resource

Download the Record (pdf)

Download the Record (pdf)

Distribution format
  • pdf

Resource lineage

Statement

Unknown

Hierarchy level
Non geographic dataset
Other

GA Publication

Description

Source data not available.

Metadata constraints

Title

Australian Government Security ClassificationSystem

Edition date
2018-11-01T00:00:00
Website

https://www.protectivesecurity.gov.au/Pages/default.aspx

Classification
Unclassified

Metadata

Metadata identifier
urn:uuid/b0140d6f-15ce-55d6-e044-00144fdd4fa6

Title

GeoNetwork UUID

Language
English
Character encoding
UTF8
Contact
Role Organisation / Individual Name Details
Point of contact

Commonwealth of Australia (Geoscience Australia)

Voice

Type of resource

Resource scope
Document
Name

GA Record

Alternative metadata reference

Title

Geoscience Australia - short identifier for metadata record with

uuid

Citation identifier
eCatId/73001

Metadata linkage

https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/metadata/b0140d6f-15ce-55d6-e044-00144fdd4fa6

Date info (Revision)
2018-04-20T06:11:48
Date info (Creation)
2011-10-25T00:00:00

Metadata standard

Title

AU/NZS ISO 19115-1:2014

Metadata standard

Title

ISO 19115-1:2014

Metadata standard

Title

ISO 19115-3

Title

Geoscience Australia Community Metadata Profile of ISO 19115-1:2014

Edition

Version 2.0, September 2018

Citation identifier
https://pid.geoscience.gov.au/dataset/ga/122551

 
 

Spatial extent

N
S
E
W


Keywords

marine seismic velocity

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