Estimation of reservoir properties of the haynesville shale by using rock-physics modelling and grid searching

Abstract

This study presents a workflow that combines an isotropic and an anisotropic effective medium model with a grid-search method to invert for the reservoir properties (porosity, composition and pore shape) of the Haynesville Shale. The reservoir properties inverted from this workflow closely matched the observed data, and they provide very useful information in determining locations with relatively high porosities and relatively large fractions of brittle components favourable for hydraulic fracturing. The isotropic effectivemedium model represents a complex medium as a single homogeneous medium by including grains and pores of different shapes and sizes. The anisotropic effectivemedium model introduces vertical transversely isotropicmedia through aligned fractures. After building the relationships between the reservoir properties and P- and S-wave velocities,we used grid searching to obtain porosity, composition and pore shape distributions conditioned by the rock-physics models. The modelled seismic velocities that satisfied criteria from objective functions provided estimated reservoir properties. The porosity and composition estimations at the well location matched the observations from log and core data quite well. The pore shape estimation suggested that the pores, cracks and fractures within theHaynesville Shale have elongated shapes. Future application of thisworkflow at the seismic scale will provide continuous spatial distributions of these reservoir properties. © The Authors 2013 Published by Oxford University Press on behalf of The Royal Astronomical Society.