Thanks to parallel computing and multi core processors, attributes computation is now fully integrated in the interpretation workflow and becomes a precise help to reveal geological features through the seismic data. PaleoScan™ proposes a large panel of attributes that can be obtained either from volumes or surfaces. Depending on the input data and the type of calculation, attributes will highlight either stratigraphy or structure. Data comparison can be performed by using interactive co-rendering data and synchronised views.
Moreover, frequency decomposition to increase the image resolution (see color blending tools) and spectral blueing to increase the seismic vertical resolution, are also available. For custom filtering, formula can be edited in a calculator offering a real time preview.
A various range of seismic attributes are available in 4 main categories
- Basic: represents simple filters, classically used to condition data such as Similarity, RMS amplitude, 3D Smoothing, Derivatives (1st and 2d), ...
- Complex: based on the Hilbert transform. These attributes are sensitive to either stratigraphic features and high amplitude contrasts (Envelope, Sweetness, Instant. Phase and Frequency, etc.)
- Frequency: based on the Fourier Transform (Low Pass, Band Pass and High Pass), including various filters..
- Structural : they are either related to a gradient vector field, directly calculated from the seismic (Variance, coherency, dip, curvature, chaos, fault probability..) or from the geologic time volume (fault throw, dip, azimuth, curvature, 3D gradient deepest descent gradient…), which is sensitive enhances fault network and can be used to refine the structural interpretation.
- Stratigraphic: mainly dependent on the derivatives of the geologic time volume, such as the thinning, which represents the vertical derivative of the geological model and highlights any stratigraphic discontinuity such as erosion, channel, canyon incision
Surface attributes computed directly from the horizon stack are also available and allow a detailed analysis of stratigraphic objects and enhance the fault network. Dip angle, Azimuth Variations, Curvature, deepest descent gradient can be computed in real time and become a drastic help to enhance major and subtle faults, where seismic image has a poor resolution.
Custom formulae can be edited in an intuitive calculator and applied on volumes, horizons or well logs, in a simple and intuitive interface. Real time preview, formula editing and saving options are also available.
Spectral Blueing method helps the interpretation of seismic areas with too low amplitude values. It is a quick technique which can be easily applied on seismic data and improves the vertical resolution of seismic volumes. Following the same workflow as Coloured Inversion, this method is based on reflectivity time series computed from acoustic impedance well logs. It defines an operator used to increase the vertical resolution of seismic data.
Thanks to the interactivity of the PaleoScan™ software, the operator can be estimated in real time and quickly convolved to the seismic volume. The operator is obtained within the following workflow:
- Average seismic spectrum estimation
- Wells reflectivity spectra in a log/log scale
- Wells impedance spectra in a log/log scale
- Fitting of a trendline through these spectra
- Compute the operator amplitude spectrum
- Zero phase rotation