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2019 Distinguished Instructor
Short Course | Manika Prasad
Physics and Mechanics of Rocks: A Practical Approach

Course Duration
One day

Intended Audience• Seismic imagers and interpreters who want to learn how fluids,

stress, and other environmental effects change seismic signatures;• Geophysicists who wish to derive rock properties and constrain

well-to-seismic ties;• Geologists and sedimentologists looking to develop predictive models

of sedimentary environments and stratigraphic events;• Reservoir engineers to build porosity, permeability and fluid coveragemodels for reservoir simulations using 3D and 4D seismic data;• Basin modelers and completions engineers to evaluate stresses fromwell log and seismic data;• Geoscientists performing formation evaluation and well logging
interpretations; and• Basin managers and team leaders who wish to evaluate accuracy ofpredictions and understand risk and errors in models.

Prerequisites (Knowledge/Experience/Education Required)

Attendees should have an understanding of basic rock properties, suchas porosity, permeability, sediment compositions and depositions, andstructural geology. It will be helpful to have familiarity, but not necessarily
expertise in seismic properties. The accompanying textbook will include
mathematical details, data, and problem solutions for mineral modulus
calculations, rock stiffness calculations for textural symmetries, velocity
binning in flow zones, pore stiffness, and Gassmann fluid substitution. The
lecture will focus on fundamental rock physics principles, applications,and analysis of results.

Course Outline

The course is organized into two main sections: Section I. Rock Physics
Fundamentals (introductory section) and II. Advanced Topics in RockPhysics (application section):
I. Rock physics fundamentals: In this section, I willa. review fundamental principles underlying rock physics, and		 rock properties;
b. investigate the effects of fluids on rock properties;
c. derive basic rock physics correlations and explain why and how they work;d. review rock properties that can be mapped with remote sensing.

SMConnecting the World of Applied Geophysics

II. Advanced Topics in Rock Physics: In this section, the student isintroduced toa. poroelasticity;b. attenuation and dispersion;c. geomechanics;d. complex electrical conductivity and permeability;
e. investigate the causes for complications and deviations from		 basic correlations;f. examine existing empirical and theoretical models;g. discuss selected case studies in rock physics.

Learner Outcomes

On completion of the course, the learner should be able to:• Describe and explain the applications of rock physics for reservoir
characterization, formation evaluation, and field monitoring.
• Identify and evaluate existing and potential technologies applicable torocks physics and rock mechanics for reservoir/formation studies.
• Identify, list, and describe physical properties of rock, and relate theseproperties to the mechanical behavior of the rocks.
• Interpret and predict the effect of mineral properties (e.g. clayminerals) on load-bearing capacity and strength of rocks.
• Integrate and model elastic wave propagation, electrical conductivity
and fluid flow in rocks.
• Evaluate and assess errors in experimental data, the uncertainty, andthe value of theoretical models.
• Develop expertise in rock physics interpretations of seismic andelectrical conductivity to identify fluids and quantify saturations.
• Gather key strengths in rock physics interpretations by developing
a broad understanding of existing or potential technology transfers
between engineering and earth science fields that relate rock physics toreservoir geophysics and reservoir engineering.
• Gain knowledge and expertise to understand physical and mechanicalbehavior of rocks through examples of stress dependent changes instrains, seismic velocity, electrical conductivity, and pore structure.
• Interpret rock physics and rock mechanics data and model elastic wave
propagation, electrical conductivity, and fluid flow in rocks.
• Assess errors in experimental data; assess the uncertainty and thevalue of rock physics models.

seg.org/DISC

2019 Distinguished Instructor Short Course — Manika Prasad
Physics and Mechanics of Rocks: A Practical Approach
These learning objectives will allow geoscientists and engineers to:• Distinguish major trends in and control factors for velocity andimpedance changes in the subsurface.
• Describe and evaluate velocity and impedance data for changes influids and stresses.
• Apply basic rock physics techniques to evaluate reservoirs.
• Identify and select the best practice workflows when using rock physics

for seismic interpretations.
• Analyze complex conductivity data to interpret reservoir properties.

Abstract

Rock physics is an interdisciplinary branch of geophysics that explains
geophysical remote sensing data, such as seismic wave velocities orelectrical conductivity in the context of mineralogy, fluid content, andenvironmental conditions. Thus, rock physics interpretations often require
input from physics, geology, chemistry, chemical engineering, and otherfields. For example, seismic waves in cemented rocks travel faster thanin loose sediments. Since the physical behavior of rocks controls theirseismic response, rock physics brings a key knowledge that helps with theinterpretation of rock properties, such as porosity, permeability, texture,and pressure. Rock physics employs indirect geophysical data, such as
seismic impedance, sonic log velocities, laboratory measurements, andpetrophysical information about porosity, fluid type, and saturation inreservoir characterization, evaluation, and monitoring. Typically, rock physics
is used by anyone doing a monitoring survey to map fluids from 4D seismic;
petroleum engineers doing reservoir simulations; geologists evaluating
over-pressures and making basin models. For all such purposes, anunderstanding of wave propagation is required to relate seismic properties(e.g. velocity and attenuation) to physical properties of rocks and to evaluate
seismic data in terms of subsurface petrophysical parameters. For example,
an application of rock physics is seen in 4D seismic data (i.e. repeatedseismic data acquired from the same field), where fluid saturation changes
are evaluated from the changes in velocity using fluid-substitution models.
Another rock physics application is for example to understand and predict
the effect of clay minerals on load-bearing capacity and strength of rocks
using fundamental knowledge about the properties of clay minerals (e.g.
CEC, surface area, dispersibility, charge, sorption, plasticity, etc.), the clay
water content, as well as the effects of their distribution within the rock.
Thus, an effective prediction of rock properties from indirect measurements
requires a solid understanding of the physical behavior of rocks under in situ
conditions of pore and confining pressures and fluids saturations.

SMConnecting the World of Applied Geophysics

During this one-day short course, I will provide the earth scientist andengineer with the fundamental basis of rock physics to describe thephysical processes that govern the response of rocks to external stresses
that are essential for reservoir characterization. The course will also offer
practical guidance to better analyze existing data. A major goal of thiscourse is to offer practical instruction and provide working knowledge in theareas of rock physics and rock mechanics for rock characterization.
Mature fields can be reborn. Overlooked deeper and shallower objectives
as well as new play concepts reinvigorate oil fields where the acerageis held and the infrastructure is in place. 5D interpolation reinvigorates
legacy seismic surveys. In North America, technical innovations including
horizontal drilling and hydraulic fracturing may directly target the sourcerock, or drill tight or highly heterogeneous parts of the reservoir too
expensive to produce from vertical wells. Our analysis becomes morestatistical, where the experience obtained from tens if not hundreds ofwells can be correlated to volumetric attributes. Using core to generate
reservoir-specific templates, seismic attributes can be statiticallycorrelated to brittleness, total organic carbon, rate of penetration, andexpected ultimate recovery.
In this one day short course, I will illustrate these concepts by example,
showing modern workflows based on interactive interpretation and display
as well as those aided bymachine learning.

Instructor Biography

Manika Prasad has been at Colorado School of Mines (CSM) for the past
14 years, and previously at Stanford University, and University of Hawai’i.
She received her BS from Bombay University and MS and PhD from Kiel
University in Germany. Prasad’s main interests lie in understanding
microstructural controls on geophysical data. She is the recipient of theVirgil Kauffman Gold Medal in 2017, Outstanding Educator Award (2015),
and the AAPG-SEG Distinguished Lecturer Award (2012). Known as the“mud queen” among her peers and students, she pioneered the integral
research in source rich rock and fluid properties using tools and techniquesfrom geoscience and engineering domains. In addition to teaching andresearch duties at CSM, Prasad serves as Associate Editor for Geophysics
and is Second Vice President of SEG.

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