Posted on May 01, 2017
All, For your possible interest, please find the recently accepted paper to the ‘Interpretation‘ Journal of the SEG in the link below along with four key references. Thank you. Warmest best regards, Art
A direct inverse method for subsurface properties: the conceptual and practical benefit and added-value in comparison with all current indirect methods, for example, AVO and FWI
Direct inverse methods solve the problem of interest, and in addition they communicate whether the problem of interest is the problem that we (the seismic industry) need to be interested in. When a direct solution doesn’t result in an improved drill success rate, we know that the problem we have chosen to solve is not the right problem —- since the solution is direct and cannot be the issue. On the other hand with an indirect method, if the result is not an improved drill success rate, then the issue can be either the chosen problem, or the particular choice within the plethora of indirect solution methods, or both. The inverse scattering series (ISS) is the only direct inversion method for a multidimensional subsurface. Solving a forward problem in an inverse sense is not equivalent to a direct inverse solution. All current methods for parameter estimation, e.g., AVO and FWI, are solving a forward problem in an inverse sense and are indirect inversion methods. The direct ISS method for determining earth material properties, defines both the precise data required and the algorithms that directly output earth mechanical properties. For an elastic model of the subsurface the required data is a matrix of multi-component data, and a complete set of shot records, with only primaries. With indirect methods any data can be matched: one trace, one or several shot records, one component, multi-component, with primaries only or primaries and multiples. Added to that are the innumerable choices of cost functions, generalized inverses, and local and global search engines. Direct and indirect parameter inversion are compared. The direct ISS method has more rapid convergence and a broader region of convergence. The difference in effectiveness increases as subsurface circumstances become more realistic and complex and in particular with band-limited noisy data.