Rock Physics Templates for Thin Sands Reservoirs - An Approach for Upscaled RPTs

Abstract

Summary Rock Physics Templates (RPTs) have been commonly used as a guide for quantitative interpretation of elastic rock properties ( Avseth, 2005 ). They allow to relate rock properties to the geological and petrophysical properties of potential reservoir facies. RPTs are commonly built using the log scale log data, and most of the time, porosity, fluid and lithology effects are considered the main drivers in the elastic rock properties response. However, there are several cases where reservoir thickness and seismic resolution can affect considerably the equivalent elastic reservoir response after upscaling, so the standard log scale RPTs may no longer be valid for seismic QI interpretation. Proper upscaling techniques would be necessary so that the RPTs can reflect the seismic frequency content. In this work we proposed a new methodology for generating upscaled RPTs using Backus average and assuming multiple 3-layer models with a variable sand body interbedded between two thick shales. A case study from Tertiary oil bearing thin sands in the Gulf of Mexico will be shown.