Southwest Research Institute®

San Antonio, Texas

3DStress®Stress Management Through Better Understanding

Founded in 1947 as an inde-pendent, nonprofit researchand development organization,Southwest Research Instituteprovides a significantresearch, engineering, andtesting resource for industry,business, and government.The Institute uses a multidisci-plinary, integrated approach tosolving complex problems inscience and applied tech-nology. As part of a long-heldtradition, patent rights arisingfrom sponsored research atthe Institute are often assignedto the client. SwRI generallyretains the rights to Institute-funded advancements.

Because Southwest ResearchInstitute (SwRI) is a multi-disciplinary research anddevelopment organization, itsscientists and engineersdevelop highly functionalapproaches to solve scientificand technical problems.

The SwRI-developed 3DStress®is an advanced software tool tointeractively analyze the ten-dency for faults and fractures toslip or dilate, based on a user-specified three-dimensional (3D)stress state. Evaluating stressesand their effects on faults andfractures is crucial to animproved understanding of:

n Fault reactivation

n Earthquake hazard

n Fault and fracture transmissivity

n Fault and fracture mineralization paths

n Fault-sealing behavior

n Tunnel and well-bore stability

n Structural geology interpretations

The 3DStress software program provides a powerful tool for predicting:

n Fault sealing

n Hydrocarbon migration routes

n Potential fracture controlled permeability

Uses of the 3DStress software include:

n Oil and gas prospect risk assessment

n Slip vector calculation for three-dimensional reconstructions

n Production planning strategy for fractured reservoirs

n Stress-state sensitivity analysis

n Well bore and tunnel stability analyses

©2007 Southwest Research Institute. All rights reserved. Southwest Research Institute, SwRI,and 3DStress are registered marks inthe U.S. Patent and Trademark Offices.

An Equal Opportunity Employer M/F/D/V

Committed to Diversity in the Workplace

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About the cover: 3DStresscolors fractures inter-secting a tunnel accordingto their slip tendency.

The Institute-developed 3DStress software features:

n Interactive graphical user interface

n Multiple levels of data input, including:

l Tabular fault and fracture orientation data

l Fault trace maps

l Well-bore data

l Density and fluid pressure gradients

l Three-dimensional seismic reflectioninterpretations

l Three-dimensional stress volume information

n Estimation of slip and dilation tendency

n Mohr circle tool for stress analysis

n Failure envelope tool for rock property analysis

3DStress software displays faults and frac-tures in three-dimensional space and colorsthem based on the following criteria:

Slip tendency: the ratio of the shear stress to the normal stress on a fault or fracturesurface:

Dilation tendency: the likelihood for a faultor fracture to dilate based on the three-dimensional stress conditions and iscomputed as:

3DStress provides an interactive tool for determiningstresses on faults and fractures, used in assessingtraps, planning wells, and characterizing faults andfractures in hydrocarbon and geothermal reservoirs.

The SwRI-developed3DStress is also used

in evaluating stability of drifts and

other undergroundexcavations in faulted

and fractured rock.

Leakage factor: similarto dilation tendency, butthe leakage factor takesinto account detailedinformation on fluidpressure and tensilestrength of fault-zone orfracture-filling material.

Slip direction: In addi-tion to slip and dilationtendency, 3DStress com-putes the expected slipdirections on faults andfractures, informationthat is crucial for accu-rate restorations, faultseal, and permeabilityanalysis.

3DStressInteractivity

To provide an environ-ment for effective inter-pretation, the softwareoffers a variety of inter-active tools, including:n A user interface for

interactive control ofthe input stressorientations and magnitudes

n Display of two-dimensional trace maps, and three-dimensionalcutoff lines and surface representations of faults and fracturescolored by slip or dilation tendency, orleakage factor

n Control of the stress field, with faultsand fractures displayed

n A lower hemisphere equal-angle stereo-graphic projection that displays fractureand fault orientations, which arecolored based on the computed sliptendency, dilation tendency, or leakagefactor

n User-defined stress fields to computethe likelihood of fault slip or fracturedilation based on the orientation of thefault or fracture

In complexly faulted areas, 3DStress can beused to distinguish fault populations andfaults that may have formed contemporane-ously during past stress conditions.Alternatively, 3DStress can be used tointerpret the contemporary stress field byinteractively optimizing the slip tendency and slip direc-tions on known active faults or to identify faults that are likely to be active or inactive in a known stress field.

Users can interactively control the stress field and viewthe results on the displayed faults and fractures.

In these fault maps of Yucca Mountain, Nevada, the slip tendency (left) anddilation tendency (right) are calculated using the present day stress field.

The combination of visual display map and the length-weighted rosediagram provides a powerful interpretation tool for geoscientists.

SwRI Business Development • San Antonio, Texas • (210) 522-2122 • Fax: (210) 522-3496 • E-mail: bd@swri.org

Southwest Research Institute is an independent, nonprofit, applied engineering and physical sciences research and developmentorganization using multidisciplinary approaches to problem solving. The Institute occupies more than 1,200 acres and providesnearly two million square feet of laboratories, test facilities, workshops, and offices for more than 3,000 employees who performcontract work for industry and government clients.

We welcome your inquiries.For additional information, please contact:

Kevin J. Smart, Ph.D., Manager 210.522.5859, Email: ksmart@swri.org

David A. Ferrill, Ph.D., Director 210.522.6082, Email: dferrill@swri.org

Space Science & Engineering Division Southwest Research Institute6220 Culebra Road, P.O. Drawer 28510 San Antonio, Texas 78228-0510Web Site: swri.org

geoscience.swri.org

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through innovative scienceand technology