Simple Elastic Inversiontm
“In a mathematical proof, elegance is the minimum number of steps to achieve the solution with greatest clarity. In dance or the martial arts, elegance is minimum motion with maximum effect. In filmmaking, elegance is a simple message with complex meaning. The most challenging games have the fewest rules, as do the most dynamic societies and organisations. An elegant solution is quite often a single tiny idea that changes everything.”
– The Elegant Solution: Toyota’s Formula for Mastering Innovation,
Matthew E. May, Free Press, 2007
OpenGeoSolutions has created an elegant solution, a new class of inversion technologies, which embodies simplicity on the far side of complexity.
- Faithful to the frequency content of the seismic data.
- Low frequency model can be added post inversion. (No need to rerun the inversion if the low frequency model changes.)
- Robust match to well log curves.
Simple Elastic Inversiontm uses a transformation of the Zoeppritz Equations enabling direct computation of elastic parameters that match corresponding filtered well log traces. These solutions are derived solely from the information carried by the seismic data and show trace to trace relative variation of the elastic parameter that is being calculated.
Simple Elastic Inversiontm requires three arbitrary angle/offset stacks and a well with dipole sonic and density over the inversion interval. Generated volumes include Density, Vp, Vs, Vp/Vs, AI, SI, GI, Kappa (Bulk Modulus), Mu (Shear Modulus), Youngs Modulus, Sigma (Poissons Ratio), Lambda (Lames Constant), Lambda Mu, Lambda Rho, and Mu Rho. Gamma-ray volumes are also possible dependent on the geological context.
The inverted volumes can serve as input to OpenGeoSolutions spectral analysis, Spectral Discontinuitytm and Spectral Inversion which may reveal subtle features not obvious on reflectivity data. Further estimation of the absolute values of the generated elastic parameters can be obtained by incorporating appropriate low frequency models.
Simple Elastic Inversiontm - A Brief Example
In this project area interpretation of the Muskwa formation is hampered by the poor acoustic impedence contrasts.
According to well logs, the top Muskwa should be clearly defined on Elastic Inversion results for Vp/Vs, Sigma, Lambda-Rho, and Lambda-Mu.
The logs also indicate that the Mid-Devonian should be seen on those elastic parameters that have a considerable shear component such as Vs, SI, GI, Mu, Youngs Modulus and Mu-Rho.
Working on the hypothesis that gamma-ray logs can indicate lithology changes...which in turn can indicate changes in elastic parameters, a band limited inversion of the gamma-ray was also conducted.
Acoustic Impedance - A challenge to interpret the Muskwa (Data Courtesy of Nexen Energy ULC)
Vp/Vs - Much better definition of the Muskwa (Data Courtesy of Nexen Energy ULC)
Shear Impedance - Much better definition of the Mid-Devonian (Data Courtesy of Nexen Energy ULC)
Gamma Ray - An interesting gamma-ray inversion (Data Courtesy of Nexen Energy ULC)