In a First Break paper out this month PGS and OilCo authors demonstrate how PGS Ultima produces more trustworthy results compared to conventional processing techniques in areas with imaging challenges.
The authors illustrate how this new simultaneous velocity and reflectivity workflow provides accurate and high-resolution attributes for better quantitative interpretation and reservoir analysis.
While the background velocity model is iteratively updated, an accurate estimate of the earth reflectivity is simultaneously generated. The resulting images show higher amplitude fidelity and higher signal-to-noise ratio.
Delivering Properties for Derisking Prospectivity
The inverted models can be used to calculate additional properties such as relative density, which is useful for improving prospectivity analysis. The simultaneous inversion products, i.e., velocity, reflectivity, and the derived relative impedance and density, besides improving individual lead evaluation, also provide better property constraints for QI and shallow anomaly interpretation. The inverted models and additional properties can be directly used to understand the petroleum system, reliably identify leads, and ultimately reduce exploration risk.
Velocity model (left) and relative density (right) model horizon extraction at the Jeffries lead from simultaneous inversion tool PGS Ultima.
Even though the two datasets are from Canada, the depth of the water column and the overall geology is quite different. However, improvement is observed using PGS Ultima on both examples and the results show significant structural improvements, more focusing, and better fault imaging compared to a conventional migration.
The simultaneous inversion takes advantage of the similarities between FWI and LSM. The scale separation based on an inverse scattering imaging condition updates the velocity and reflectivity with minimum crosstalk between the two models. Particularly, reflectivity changes caused by density variations are not erroneously mapped as velocity updates.
Read the full paper Estimating reliable earth properties from simultaneous velocity and reflectivity inversion
Future Work to Generate Angle Gathers
The current implementation of the simultaneous inversion is based on stacked vector reflectivity. The next development step is to extend the inversion to generate angle gathers, which can provide more properties to help quantitative interpretation of potential hydrocarbon prospects.
Learn More about PGS Ultima | Webinar from Nick Montevechhi, OilCo
Nick showcases the application of PGS Ultima in the frontier exploration areas of the Orphan and Salar Basins, offshore Newfoundland and Labrador. Nick says "The products from PGS Ultima show significant uplift over traditional velocity model building and imaging workflows. This increases confidence in the evaluation of the subsurface potential for frontier explorers."
Register here for the webinar Estimating Reliable Earth Properties and Understanding Prospectivity Offshore Newfoundland using PGS Ultima.
Contact a PGS expert
Please contact a member of our Canada team for more information.