Spectral Inversion / Count Between Thresholds (CBT)
An analytic trace by trace inversion of amplitude spectra reveals the underlying subsurface layering architecture. We analytically transform spectral interference to layer stacking patterns. This allows us to quantitatively characterize reflective boundaries and thicknesses of layers. This process does not require a background model or well-constraints. It only requires the seismic data and a horizon that is roughly conformable to the zone of interest. Once the inversion is complete, well-data can be overlain for QC and benchmarking.
The layering dataset can be used within conventional interpretation software as a seismic
volume:
- to pick layer boundaries
- to overlay well and cultural information
- to integrate the defined layering within the team's existing interpretation framework.
- to investigate layer thickness
OGS spectral inversion reveals 3-D layering distribution, If AVO products such as Elastic Inversion are deemed useful for lithology and fluid prediction, then spectral inversion of such products will provide better resolved characterization of the lithology and fluid distribution.
Count Between Thresholds (CBT) takes advantage of the probabilistic nature of Spectral Inversion. Spectral Inversion amplitude represents prediction confidence. The higher the amplitude (positive or negative) the greater the confidence in the prediction. Thresholding the layering solution, with respect to prediction confidence enables insights into the geometry, thickness and connectivity of the subsurface architecture.
Spectral Inversion (Data Courtesy of Nexen and CNOOC)
Count Between Thresholds (Data Courtesy of Nexen Energy ULC)