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Seismic to well ties
Accurate calibration between seismic data in the time domain and well data in the depth domain is essential for confident inversion results. We use a suite of AVO modelling and wavelet estimation tools designed for varying degrees of well control and data quality, allowing unnecessary assumptions to be discarded in favour of unbiased, robust wavelet estimates.
To calibrate seismic data obtained in the time domain to well data obtained in the depth domain, a detailed time-depth analysis followed by wavelet estimation must be performed. This also requires an accurate evaluation of the angle dependent reflectivity response for the extraction of a reliable wavelet.
Our suite of AVO modelling and wavelet estimation tools is designed for varying degrees of well control and data quality. With these tools, unnecessary assumptions can be discarded, allowing for an unbiased and more reliable wavelet estimation.
"A reliable seismic-to-well tie is the calibration point for the entire inversion workflow. If the time-depth relationship, angle-dependent reflectivity and wavelets are wrong, the inversion may look precise — but it will not be reliable."
Qeye's wavelet estimation techniques
Qeye’s wavelet estimation workflow includes a set of proprietary technologies designed to produce high-quality, angle-dependent wavelets for reliable seismic inversion.
The workflow typically includes:
- Calculation of angle-dependent reflectivity series from relevant well logs
- Well-to-seismic tie
- Single-well or multi-well wavelet estimation for each angle stack and vintage
The angle reflectivity calculation starts with resampling the relevant well logs, typically sonic, shear sonic and density. Optional inputs such as elastic moduli and compressibilities can also be included when Backus averaging is required.
Log resampling is based on a check-shot and visually constrained depth-to-time conversion using linear or cubic spline functions. Where appropriate, physically consistent velocities can be used. To avoid aliasing, a non-equidistant zero-phase Butterworth filter is applied before interpolation to the regular seismic time sampling.
The depth-to-two-way-time conversion can also include Backus averaging to account for dispersion effects. This often reduces the need for manual visual tie adjustments.
Qeye supports both single-well and multi-well wavelet estimation. The multi-well workflow can be performed in two ways:
Multi-well simultaneous estimation
A single wavelet is estimated by optimally fitting the input well reflectivities and seismic data simultaneously, using the selected estimation method.
Multi-well independent estimation
Wavelets are estimated independently for each well and then combined by averaging their amplitude and phase spectra.
This flexible workflow enables consistent wavelet estimation across angle stacks and vintages, supporting robust 3D and 4D AVO inversion.