Lamda-mu-rho technique as a viable tool for litho-fluid discrimination - The Niger-Delta example

Abstract

The focus of this paper is to discriminate fluid and lithology in the tertiary Niger Delta using the Lamda-mu-rho technique. This involves the use of basic rock Physics, Amplitude Variation with Offset (AVO), and seismic amplitude inversion to show the effectiveness of this technique in an oil sand reservoir. The data used in this study include pre-stack seismic data and well log data. The result shows the effectiveness of this technique for litho-fluid discrimination irrespective of the geological setting. For over a decade, there has been a lot of interest in the extraction of information from Amplitude Variations with Offset (AVO) for the determination of fluid content of reservoirs.The work of Goodway et al, 1997, Gray and Anderson, 2000 have shown with great success the Lambda-murho technique for litho- fluid discrimination. This has wide application in exploratory work and development of reservoirs in various geological settings. Despite the robustness of their work, David Gray 2001 suggested the extraction of the fundamental rock properties l and m with the exclusion of density term r.The work was found to be an improvement on Goodway’s method in that it produced data that were less noisy and stable (Quakenbush et al., 2006). Reservoir characterization requires the detection, identification, and quantification of thickness, porosity, permeability, and fluid content. Unfortunately, many of these reservoir parameters are not derivable from seismic data. The only elastic parameters derivable from seismic data are the Lame’s Constant (l,m), velocity, poisson’s ratio and impedances. This is due to the fact that these mentioned parameters are directly responsible for seismic amplitude variation. In this paper, a simultaneous inversion of prestack seismic data was done with a view to obtaining the acoustic and shear impedances. The aim was to verify Goodway et al. (1997) technique as a viable tool for discriminating oil sand from shales within a reservoir in the Niger Delta region of Nigeria. Key words: Fluid, lithology, Niger Delta, AVO, Lamda-mu-rho, discrimination.