Lambda-rho Poisson’s ratio multiplication as a seismic fluid indicator and a review of mapping subsurface fluids with elastic properties

Abstract Elastic parameters, their combinations, and cross-plots are frequently used for mapping subsurface fluids in exploration, appraisal, and development of hydrocarbons, and in other areas where monitoring produced and injected fluids is essential, such as in time-lapse seismic or carbon capture storage. Seismic interpreters worked with different seismic data sets, i.e., inversion products, amplitude versus offset (AVO) volumes, or angle stacks. The study discussed how interpreters approximated relative values (reflectivities) of common elastic properties from seismic data by weighting angle stacks or as chi-angle projections from AVO parameters. Furthermore, a review of lambda-rho and Poisson’s ratio multiplication was presented as a fluid indicator. It was demonstrated how the product approximated two other important fluid indicators: the moduli difference and the fluid-rho method and illustrated how it generated a nonlinear gain to boost fluid signal, significantly enhanced the sensitivity for discrimination. This multiplication acted as a double-gate filter for fluid detection because both parameters had to decrease simultaneously in the presence of hydrocarbons. A re-parameterization of the AVO equation was proposed to extract reflectivities of lambda-rho, Poisson’s ratio, and density simultaneously from prestack data. This review and case study helped to increase awareness of the importance of using elastic properties in seismic mapping of subsurface lithologies and fluids.