Authors / CoAuthors
Johnston, S.W. | Goncharov, A.
Abstract
A method for calibrating seismic stacking velocities against velocities from well measurements has been developed to quantitatively assess the validity of stacking velocities in the vicinity of boreholes and to improve quality of stacking velocities for use in regional depth conversion of interpreted seismic horizons. Accurate depth conversion of seismic interpretation is vital for use as constraints in gravity modelling and in other basin modelling tasks. Examples of this methodology are given for the northern Perth Basin, Australia. The suggested workflow for calibrating seismic stacking velocities against well velocities in a simplified form 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 two-way time and depth domain 4. Resample all velocity datasets to the same two-way time intervals 5. Cross plot stacking velocity depths near a well site with corresponding well depths for equal two-way times 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 ±50 m down to the maximum well depth analysed (3.5 km below sea floor); this depth uncertainty translates into a modelled gravity anomaly error of about ±20 gu, which is acceptable for regional scale gravity modelling.
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nonGeographicDataset
eCat Id
73286
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
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2601
Australia
Keywords
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- External PublicationAbstract
- ( Theme )
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- seismic velocity
- ( Theme )
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- geophysics
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2012-01-01T00:00:00
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