TITLE PAGE Title: Seismic and Rockphysics Diagnostics of Multiscale Reservoir Textures

As part of our study on “Relationships between seismic properties and rock microstructure”, we have studied 1. Methods for detection of stress-induced velocity anisotropy in sands. 2. We have initiated efforts for velocity upscaling to quantify long-wavelength and short-wavelength velocity behavior and the scale-dependent dispersion caused by sediment variability in different depositional environments. TABLE OF CONTENTS TITLE PAGE. 1 DISCLAIMER . 2 ABSTRACT. 3 TABLE OF CONTENTS. 4 LIST OF GRAPHICAL MATERIALS. 5 INTRODUCTION. 6 PAPER 1 . 7 PAPER 2 . 8 BIBLIOGRAPHY . 34 LIST OF GRAPHICAL MATERIALS Paper 1: Total of five figures in paper. 7 Paper 2: Total of nine figures in paper. 8 INTRODUCTION In this quarter, we submit results of our research on: pore textural mapping and its relation to centimeter-scale core measurements of impedance and measurements of seismic properties of unconsolidated sediments at very low effective pressures. The special effect of stress anisotropy on velocity anisotropy is investigated. Two papers have been submitted for publication. This report presents preprints of our research relevant to this project on impedance mapping, soft-sediment measurements, stress anisotropy, and scale effects. PAPER 1 Vega, S. , Prasad, M. , Mavko, G. , and Nur, A. , Detection of stress-induced velocity anisotropy in sands. Submitted to GRL In this paper, we present a preliminary study on stress-induced velocity anisotropy in two different sands. We describe the method used for sample preparation, and the polyaxial apparatus used for velocity, strain, and stress measurements. Furthermore, we examine the velocity response as a function of stress in different directions of applying uniaxial strain test to the samples. The strains and velocities of the two sands are also compared. We show that stress-induced velocity anisotropy exists and is detectable in sands. A stress anisotropy of 87% corresponds to a velocity anisotropy of 29%-34%, and there is a linear dependency of velocity anisotropy on stress anisotropy in the sands. Paper 1: Total of five figures in paper PAPER 2 Mukerj, T. , and Prasad, M. Image processing of SAM data to estimate textural scales and anisotropy: abbreviated form submitted for the SEG Annual Conference to be held in Dallas in October 2003. We apply different statistical methods for characterizing heterogeneity and textures from scanning acoustic microscope (SAM) images of shale microstructures. Characterizing and understanding the microgeometry, their textures, scales, and textural anisotropy is important for better understanding the role of microgeometry on effective elastic properties. We analyzed SAM images from Bakken shale, Bazhenov shale, and Woodford shale. Our analysis, based on spatial autocorrelation functions shows that there is a small positive correlation between the degree of heterogeneity and the mean spatial correlation length of the microstructure. The textural anisotropy ranges from 10% to 80%. There is considerable variability within each image, as well as from one image to another. A singular value decomposition (SVD) spectral analysis showed that the shale microstructures have characteristics in common with fractal stochastic images. We also obtain a correlation between maturity and textural heterogeneity. The textural heterogeneity increases with increasing maturity (decreasing kerogen content), while there is a general decrease in textural anisotropy with maturity. The accompanying paper A4 in this volume relates the textural characteristics obtained from image processing to characteristics obtained from ultrasonic measurements. Paper 2: Total of nine figures in paper Detection of stress-induced velocity anisotropy in sands Sandra Vega, Manika Prasad, Gary Mavko, and Amos Nur Stanford Rock Physics Laboratory Abstract In this paper, we present a preliminary study on stress-induced velocity anisotropy in two different sands. We describe the method used for sample preparation, and the polyaxial apparatus used for velocity, strain, and stress measurements. Furthermore, we examine the velocity response as a function of stress in different directions of applying uniaxial strain test to the samples. The strains and velocities of the two sands are also compared. We show that stress-induced velocity anisotropy exists and is detectable in sands. A stress anisotropy of 87% corresponds to a velocity anisotropy of 29%-34%, and there is a linear dependency of velocity anisotropy on stress anisotropy in the sands.In this paper, we present a preliminary study on stress-induced velocity anisotropy in two different sands. We describe the method used for sample preparation, and the polyaxial apparatus used for velocity, strain, and stress measurements. Furthermore, we examine the velocity response as a function of stress in different directions of applying uniaxial strain test to the samples. The strains and velocities of the two sands are also compared. We show that stress-induced velocity anisotropy exists and is detectable in sands. A stress anisotropy of 87% corresponds to a velocity anisotropy of 29%-34%, and there is a linear dependency of velocity anisotropy on stress anisotropy in the sands.