3DStress® provides a user-friendly and interactive tool to investigate geologic stress states and effects on developing and reactivating faults and fractures. Components include Mohr circle plots with Hoek-Brown failure criteria, stress-ratio plots, stereonet and 3-dimensional visualization tools to enable the user to illustrate hypothetical situations or complex real-world fault and fracture systems, and a patented stress inversion algorithm that does not require slip direction information.
3DStress is used in the oil and gas, and geothermal industries, and by regulators of drilling and high-level radioactive waste disposal.
The software's straightforward interactive and intuitive approach to stress analysis makes it especially useful in the classroom.
3DStress Applications (click to expand):
- Intuitive understanding of the stress tensor
Slip tendency is the ratio of the shear stress to the normal stress on a fault or fracture surface:
Dilation tendency is the likelihood for a fault or fracture to dilate based on the 3D stress conditions and is computed as:
Leakage factor is similar to dilation tendency, but it takes into account detailed information on fluid pressure and tensile strength of fault-zone or fracture-filling material.
In addition to slip and dilation tendency, 3DStress computes the expected slip direction by finding the maximum shear stress for the fault surface.
Simply changing the magnitude of σ2 can significantly alter the range of likely fault orientations.
- Seismic hazard assessment
3DStress and slip tendency analysis have been used to identify possible seismic sources in the evaluation of high level radioactive waste disposal sites and engineered geothermal systems.
Natural seismicity associated with the Little Skull Mountain earthquake near Yucca Mountain, Nevada:
Analysis uses a vertically varying stress state developed in part by inverting the focal mechanisms obtained from the main shock and aftershock sequence, 3-dimensional models of range bounding faults and published fault trace maps.
- Fault seal analysis
High slip tendency portions of faults and fractures are more conductive of fluids than other parts. Decreasing formation pressure can decrease a fault’s ability to transmit fluid.
- Induced seismicity evaluation
Reservoir stimulation for both hydrocarbon and geothermal energy production can induce earthquakes. 3DStress has been used to successfully plan and interpret stimulation programs in geothermal and hydrocarbon reservoirs.
- Stress inversion
3DStress uses a patented stress inversion technique to estimate stress states from fault orientations and displacement using slip tendency analysis. Fault displacement can be broadly defined as measured slip, throw, fault area, seismic magnitude, or seismic semblance. Applications include paleostress analysis, microseismicity and hydraulic fracturing stress estimation, and use of natural seismicity to estimate crustal stress states.
- Geothermal reservoir characterization
Fault patterns and stress changes expected during geothermal energy production can be modeled and the slip tendency patterns can help predict likely fluid pathways through the reservoir.
- Hydraulic fracturing/well completion design and analysis
Natural fractures can sometimes be targeted for reactivation during hydraulic fracturing, slip tendency analysis can help identify those parts of a well that are most likely to be reactivated during “fracking.”
- Fracture network and reservoir permeability anisotropy
Because fractures experiencing high slip tendency are more transmissive of fluid than others, a slip tendency analysis can provide information on which fractures within a complex system are more likely to be an active part of the permeability architecture.
3DStress used to identify the most transmissive fractures in a fracture network.
- Importance of the intermediate principal stress
The magnitude of the intermediate principal stress can have a very important effect on the orientations and number of factures and faults that are potentially active in a stress state. This can affect the permeability architecture and the strength of the rock mass.
Ferrill, D. A., Winterle, J., Wittmeyer, G., Sims, D., Colton, S., Armstrong, A., Morris, A. P., 1999. Stressed Rock Strains groundwater at Yucca Mountain, Nevada: GSA TODAY, v. 9, p. 1–8.
McFarland, J., Morris, A. P., Ferrill, D. A., 2012. Stress inversion using slip tendency. Computers & Geosciences, v. 41, p. 40–46.
Moeck, I., Kwiatek, G., Zimmermann, G., 2009, Slip tendency, fault reactivation potential and induced seismicity in a deep geothermal reservoir. Journal of Structural Geology, v. 3, p. 1174–1182.
Morris, A. P., Ferrill, D.A., Henderson, D.B., 1996. Slip Tendency and Fault Reactivation: Geology, v. 24, p. 275–278.
Morris, A. P., Ferrill, D. A. , 2009. The importance of the effective intermediate principal stress (σ΄2) to fault slip patterns. Journal of Structural Geology, v. 31, p. 950–959.
Morris, A. P., Smart, K. J., Ferrill, D. A., Reisch, N. E., Cowell, P. F., 2012, Production-induced fault compartmentalization at Elk Hills field, California. American Association of Petroleum Geologists Bulletin v. 96, p. 1001–1015.
Earth sciences and engineering • stress analysis • computer modeling • visualization technology • geologic faults • geologic fractures • slip tendency • dilation tendency • leakage factor • seismic hazard analysis • fault hazard analysis • geomechanics • reservoir engineering • structural geology • slip direction • hydrocarbon trap evaluation