21 results on '"Horizontal stress"'
Search Results
2. Spatially Varying Stress State in the Central U.S. From Bayesian Inversion of Focal Mechanism and In Situ Maximum Horizontal Stress Orientation Data
- Author
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Ray Y. Chuang, Kaj M. Johnson, Grace Carlson, and John A. Rupp
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In situ ,Focal mechanism ,010504 meteorology & atmospheric sciences ,Geometry ,State (functional analysis) ,Orientation (graph theory) ,010502 geochemistry & geophysics ,01 natural sciences ,Stress (mechanics) ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Bayesian inversion ,Earth and Planetary Sciences (miscellaneous) ,Horizontal stress ,Geology ,0105 earth and related environmental sciences - Published
- 2018
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3. Changes in paleostress state along a subduction zone preserved in an on-land accretionary complex, the Yokonami mélange in the Cretaceous Shimanto Belt, Kochi, southwest Japan
- Author
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Yodai Ueda, Mio Eida, and Yoshitaka Hashimoto
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geography ,geography.geographical_feature_category ,Deformation (mechanics) ,Subduction ,Fault (geology) ,Cretaceous ,Paleostress ,Accretionary complex ,Stress (mechanics) ,Geophysics ,Geochemistry and Petrology ,Horizontal stress ,Petrology ,Geology ,Seismology - Abstract
A change in paleostress along a subduction zone plate interface in the shallow portion of a seismogenic zone was detected in an on-land accretionary complex, the Yokonami melange in southwest Japan, using the microfault inversion method. Microfaults were classified into two groups based on location: those occurring throughout the Yokonami melange and those occurring in the Goshikinohama fault zone, which is considered to be a fossil seismogenic fault and is located at the northern end of the Yokonami melange. Stresses obtained for these classified microfaults indicate that two different stress states exist for each deformation feature: one is subhorizontal σ1 and subvertical σ3 with a smaller stress ratio, and the other is subvertical σ1 and subhorizontal σ3 with a larger stress ratio. The difference between these stress states could be related to the horizontal stress change by stress drop after large earthquakes that were recently observed after the Tohoku-Oki great earthquake.
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- 2014
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4. State of stress in Texas: Implications for induced seismicity
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Jens-Erik Lund Snee and Mark D. Zoback
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010504 meteorology & atmospheric sciences ,Induced seismicity ,Structural basin ,010502 geochemistry & geophysics ,01 natural sciences ,Extensional definition ,Stress field ,Stress (mechanics) ,Geophysics ,Intraplate earthquake ,General Earth and Planetary Sciences ,Horizontal stress ,Growth fault ,Geology ,Seismology ,0105 earth and related environmental sciences - Abstract
Compilation of almost 200 new maximum horizontal stress (SHmax) orientations in Texas reveals a complex intraplate stress field. A large extensional stress province is associated with extensive growth faulting from northeastern Mexico to Louisiana. SHmax is subparallel to the coastline, following the strikes of the growth faults. In contrast, we observe a strike-slip/normal faulting regime with SHmax approximately E-W in much of west Texas and the Texas Panhandle, similar to the stress fields observed in northeast New Mexico and north-central Oklahoma. Within the Fort Worth Basin in northeast Texas, SHmax is NNE-SSW. The faulting regime transitions from strike-slip/normal faulting in the northern part of the basin to normal faulting with subequal horizontal principal stress magnitudes further south. Recent sites of apparently injection-related seismicity near Snyder/Cogdell (west Texas), Karnes City/Fashing (south Texas), the Dallas-Fort Worth metroplex, and Timpson (east Texas) involves fault slip compatible with local stress fields.
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- 2016
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5. Characterizing the Potential for Injection-Induced Fault Reactivation Through Subsurface Structural Mapping and Stress Field Analysis, Wellington Field, Sumner County, Kansas
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Drew R. Schwab, Michael H. Taylor, and Tandis S. Bidgoli
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010504 meteorology & atmospheric sciences ,Pore fluid pressure ,Slip (materials science) ,Induced seismicity ,010502 geochemistry & geophysics ,01 natural sciences ,Stress field ,Precambrian ,Geophysics ,Structural mapping ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Enhanced oil recovery ,Horizontal stress ,human activities ,Seismology ,Geology ,0105 earth and related environmental sciences - Abstract
Kansas, like other parts of the central U.S., has experienced a recent increase in seismicity. Correlation of these events with brine disposal operations suggests pore fluid pressure increases are reactivating preexisting faults, but rigorous evaluation at injection sites is lacking. Here we determine the suitability of CO2 injection into the Cambrian-Ordovician Arbuckle Group for long-term storage and into a Mississippian reservoir for enhanced oil recovery in Wellington Field, Sumner County, Kansas. To determine the potential for injection-induced earthquakes, we map subsurface faults and estimate in situ stresses, perform slip and dilation tendency analyses to identify well-oriented faults relative to the estimated stress field, and determine the pressure changes required to induce slip at reservoir and basement depths. Three-dimensional seismic reflection data reveal 12 near-vertical faults, mostly striking NNE, consistent with nodal planes from moment tensor solutions from recent earthquakes in the region. Most of the faults cut both reservoirs and several clearly penetrate the Precambrian basement. Drilling-induced fractures (N = 40) identified from image logs and inversion of earthquake moment tensor solutions (N = 65) indicate that the maximum horizontal stress is approximately EW. Slip tendency analysis indicates that faults striking
- Published
- 2017
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6. Factors controlling satiated relative permeability in a partially-saturated horizontal fracture
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Harihar Rajaram, Robert J. Glass, and Michael J. Nicholl
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Permeability (earth sciences) ,Geophysics ,Mathematical model ,General Earth and Planetary Sciences ,Geotechnical engineering ,Mechanics ,Horizontal stress ,Relative permeability ,Saturation (chemistry) ,Tortuosity ,Power law ,Reynolds equation - Abstract
Recent work demonstrates that phase displacements within horizontal fractures large with respect to the spatial correlation length of the aperture field lead to a satiated condition that constrains the relative permeability to be less than one. The authors use effective media theory to develop a conceptual model for satiated relative permeability, then compare predictions to existing experimental measurements, and numerical solutions of the Reynolds equation on the measured aperture field within the flowing phase. The close agreement among all results and data show that for the experiments considered here, in-plane tortuosity induced by the entrapped phase is the dominant factor controlling satiated relative permeability. They also find that for this data set, each factor in the conceptual model displays an approximate power law dependence on the satiated saturation of the fracture.
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- 2000
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7. A note on a method for measuring the transport properties of a formation using a single well
- Author
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Kent Novakowski, P. A. Lapcevic, Edward A. Sudicky, and J. Voralek
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geography ,Engineering ,Yield (engineering) ,geography.geographical_feature_category ,Field (physics) ,business.industry ,Mechanics ,Physics::Geophysics ,Ambient flow ,TRACER ,Geotechnical engineering ,Horizontal stress ,business ,Oil shale ,Matrix diffusion ,Water Science and Technology ,Water well - Abstract
For some subsurface investigations of contaminant transport, particularly those conducted in consolidated material, the costs related to well construction prohibit the installation of a comprehensive field of monitoring wells. To alleviate this problem for fractured, low-porosity formations, a method for measuring transport properties using a single well was developed. The method involves the injection of fluid and tracer over a short duration which establishes a radial source condition in the formation. Following this the ambient flow is allowed to carry the tracer back through the injection well where tracer concentration is monitored passively, in situ. To interpret the experimental results, a numerical model was adapted to account for the mass balance of solute in the source/monitoring well during the injection and monitoring periods. The model accommodates advection-dispersion, adsorption, decay, and matrix diffusion in a framework of fractures having a variety of geometries. To illustrate the use of the method, a field experiment was conducted using a single well which is intersected by a discrete horizontal fracture in a flat-lying shale and limestone formation. Interpretation of the results agreed well with the interpretation of other tracer experiments conducted previously in the same fracture plane. This suggests that the method may yield defensible estimates of transport properties such as matrix porosity and groundwater velocity in geological formations that are expensive and difficult to characterize.
- Published
- 1998
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8. Changes in orientation of near-surface stress field as constraints to mantle viscosity and horizontal stress differences in eastern Canada
- Author
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Patrick Wu
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Stress field ,Viscosity ,Tectonics ,Geophysics ,Rheology ,Surface stress ,General Earth and Planetary Sciences ,Horizontal stress ,Geodesy ,Holocene ,Mantle (geology) ,Geology - Abstract
Observations indicate that the orientation of the stress field in Eastern Canada has changed significantly during the last 9,000 years. If this temporal rotation of stress orientation is due to changes of the dominant stress component from rebound stress 9,000 years ago to tectonic stress at the present, then this rotation in stress orientation can be used to constrain mantle viscosity and the difference between the horizontal tectonic (principal) stresses. Rebound stress in a Maxwell earth due to the application of a realistic ice load is calculated with the Finite Element method and is superposed on tectonic stress to give the total stress. It is demonstrated that large tectonic stress differences (>10 MPa) or high viscosity (≥ 1022 Pa-s) in the lower-mantle cannot explain this temporal stress rotation because in the former case, stress orientation is determined by the static tectonic stress while for the latter case, rebound stress continues to dominate the current stress orientation.
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- 1996
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9. Correction to 'Principal horizontal stress orientations prior to the 2011 Mw9.0 Tohoku-Oki, Japan, earthquake in its source area'
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Yoshinori Sanada, Yuzuru Yamamoto, Weiren Lin, Yoshitaka Hashimoto, Saneatsu Saito, and Toshiya Kanamatsu
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Geophysics ,Breakout ,Source area ,Principal (computer security) ,General Earth and Planetary Sciences ,Horizontal stress ,Geology ,Seismology - Published
- 2011
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10. Rupture process of four medium-sized earthquakes that occurred in the Gulf of California
- Author
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Yuji Yagi, Roberto Ortega, Luis Quintanar, Héctor E. Rodríguez-Lozoya, and Cecilio J. Rebollar
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Seismometer ,Atmospheric Science ,Ecology ,Seismic moment tensor ,Borehole ,Paleontology ,Soil Science ,Forestry ,Slip (materials science) ,Aquatic Science ,Oceanography ,Strike-slip tectonics ,Geodesy ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Seismic moment ,Horizontal stress ,Aftershock ,Geology ,Seismology ,Earth-Surface Processes ,Water Science and Technology - Abstract
[1] Four medium-sized earthquakes (M w Global CMT project 5.5, 5.6, 5.9, 6.3; hereinafter named Topolobampo, Angel de la Guarda, San Lorenzo, and Loreto earthquakes, respectively) located in the Gulf of California Extensional Province were studied to obtain their kinematic rupture processes. A network of broadband seismic stations located around the Gulf of California recorded the events (Network of Autonomously Recording Seismographs-Baja and Red Sismica de Banda Ancha). Inversion of the seismic moment tensor and body waveform modeling were used to obtain the fault geometry and slip distribution on the fault plane, respectively. From these analyses, we obtained source depths of the order of 5.5 ± 0.5 km. We found also that the source rupture processes of the Topolobampo and Angel de la Guarda events have simple moment rate functions and source time durations of 5.0 ± 1.2 and 4.2 ± 1.2 s, respectively. The Topolobampo event was a right-lateral strike-slip event, and Angel de la Guarda was a normal event. The San Lorenzo and Loreto shocks show a rather complex rupture, with source time durations of 7.5 ± 1.2 and 9.0 ± 1.2 s, respectively. For these earthquakes, we tested the resolution of numerical results, performing an extra inversion with smoother waveforms. The new inversions do not show the separated patches of slip, as in the first analysis, but the slip distribution has an elongated shape not characteristic of simple events. We cannot therefore conclude rupture propagation for the San Lorenzo event, although the extent of the patch for the Loreto earthquake agrees with aftershock locations. Estimates of source time durations for these earthquakes are at the upper limit of the values found for earthquakes elsewhere. Directions of P axes are in the same order of magnitude as the maximum horizontal stress obtained for the socalled Gulf of California stress province from borehole elongations, focal plane solutions, and fault slip data.
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- 2008
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11. Stress orientation inferred from shear wave splitting in basement rock at Cajon Pass
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T. L. Henyey, Peter Leary, and Yong-Gang Li
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Stress (mechanics) ,Seismic anisotropy ,Geophysics ,San andreas fault ,Orientation (geometry) ,General Earth and Planetary Sciences ,Geophone ,Shear wave splitting ,Horizontal stress ,Polarization dependent ,Geology ,Seismology - Abstract
S-waves generated by mode conversion of P-waves from surface compressional sources and recorded by oriented geophones at depths between 1300 and 1820 meters in the Cajon Pass scientific drillhole arrive at higher apparent velocities when polarized along the direction N70°E than when polarized in the orthogonal direction. The observed polarization dependent velocities are consistent with seismic anisotropy due to in situ fractures or cracks that are preferen tially aligned N70°E (subnormal to the San Andreas fault). This result is consistent with the maximum principal horizontal stress direction at Cajon Pass also being subnormal to the San Andreas fault.
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- 1988
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12. Characteristics of regional stresses in Alaska and neighboring areas
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K. Aki, H. Pulpan, Guy Tytgat, and N. N. Biswas
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geography ,Geophysics ,geography.geographical_feature_category ,Archipelago ,technology, industry, and agriculture ,population characteristics ,General Earth and Planetary Sciences ,social sciences ,Horizontal stress ,health care economics and organizations ,geographic locations ,Geology ,Seismology - Abstract
Earthquake focal mechanisms for a selected group of crustal earthquakes located in Alaska and neighboring areas have been compiled from various sources and regional characteristics of the horizontal stress have been deduced for the region from the mechanism solutions. The results show that the compressional stress regime of southern coastal areas continues inland through central Alaska and extends in a northeast direction. The western part of Alaska, including Chukotka and the Bering Sea adjoining Alaska and the Aleutian Island chain constitute a tensional stress regime.
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- 1986
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13. In situ stress orientation near the San Andreas Fault: Preliminary results to 2.1 km depth from the Cajon Pass Scientific Drillhole
- Author
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Gadi Shamir, Colleen A. Barton, and Mark D. Zoback
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Stress field ,Geophysics ,San andreas fault ,Shear stress ,Borehole ,General Earth and Planetary Sciences ,Slip (materials science) ,In situ stress ,Horizontal stress ,Anisotropy ,Seismology ,Geology - Abstract
Stress-induced wellbore breakouts were analyzed in the Cajon Pass Scientific Drillhole (4.3km NE of the San Andreas fault) to determine the orientation of the principal horizontal stresses, using borehole televiewer digitized data. In the depth interval 1750-2115 m the mean orientation of the maximum horizontal stress is 073°. The scatter in the orientation of breakouts is as much as ±37°, and variations occur with wavelengths of few hundred meters in this interval, reflecting either true changes in stress orientation with depth or the variability of rock anisotropy. All the measured orientations, however, result in left-lateral shear stress resolved onto planes parallel to the San Andreas fault, contrary to its post Miocene right-lateral slip of ∼ 300 km. The stress orientation is consistent, however, with reported left lateral displacement across the Cleghorn fault (3 km northeast of, and possibly subparallel to the San Andreas near Cajon Pass) since the Pleistocene. The Cajon Pass stress orientation may reflect the current state of stress across the San Andreas fault, in which case it should change prior to right lateral slip on this fault, or a shallow local perturbation to the San Andreas stress field, in which case it should rotate couterclockwise with depth. Determination of the stress orientations at greater depths in the Cajon Pass drillhole will better sample the near field of the San Andreas fault and help resolve this question.
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- 1988
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14. Stress-induced borehole elongation: A comparison between the four-arm dipmeter and the borehole televiewer in the Auburn Geothermal Well
- Author
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Richard A. Plumb and Stephen H. Hickman
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Atmospheric Science ,Ecology ,Stress induced ,Borehole ,Paleontology ,Soil Science ,Forestry ,Aquatic Science ,Oceanography ,Geophysics ,Hydraulic fracturing ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Calipers ,Comminution ,Elongation ,Horizontal stress ,Geothermal gradient ,Geology ,Seismology ,Earth-Surface Processes ,Water Science and Technology - Abstract
The nature and origin of borehole elongation recorded by the four-arm dipmeter calipers is studied utilizing information obtained from hydraulic fracturing stress measurements and borehole televiewer data taken in a well located in Auburn, New York. A preferred orientation N10°W-S10°E, ±10° and a less prominant E-W orientation of borehole elongation, was observed on two runs of the dipmeter. Comparisons of borehole geometry determined using the televiewer and the dipmeter show that both tools give the same orientation of borehole elongtion provided that the zone of elongation is longer than 30 cm. Comparisons of dipmeter caliper data with orientation of in situ stress and natural fractures, obtained from hydrofracturing tests and televiewer data show that the N10°W-S10°E borehole elongations (1) are axisymmetric, (2) are aligned with the minimum horizontal stress Sh, and (3) are not associated with natural fractures intersecting the well. These elongations are interpreted as stress-induced well bore breakouts. The E-W elongation direction is characterized by an asymmetric borehole cross section in thinly bedded rocks and is not caused by breakouts. This asymmetric geometry can be discriminated from breakouts using the oriented electric measurements provided by the dipmeter. This study demonstrates that the dipmeter can be used to determine the orientation of Sh (by mapping breakouts), confirming the results of earlier less detailed studies, and provides a firm basis for mapping regional stress patterns using existing dipmeter data.
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- 1985
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15. Can the state of stress be determined from hydraulic fracturing data?
- Author
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P. E. Gretener
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Atmospheric Science ,Well stimulation ,Soil Science ,Aquatic Science ,Oceanography ,law.invention ,Stress (mechanics) ,Hydraulic fracturing ,Geochemistry and Petrology ,law ,Earth and Planetary Sciences (miscellaneous) ,Geotechnical engineering ,Horizontal stress ,Earth-Surface Processes ,Water Science and Technology ,Ecology ,Paleontology ,Forestry ,Mechanics ,State (functional analysis) ,Overburden pressure ,Geophysics ,Pressure measurement ,Space and Planetary Science ,Comminution ,Geology - Abstract
In 1957 Hubbert and Willis demonstrated that under favorable conditions two principal stresses can be determined from hydraulic fracturing data. More recently Scheidegger [1960, 1962], Dunlap [1963], and Kehle [1964] have determined all three principal stresses from such data. The latter authors concluded that the maximum horizontal stress is either of the same order of or in many instances appreciably greater than the overburden pressure. It can be shown, however, that the high values for the maximum horizontal stress are a consequence of the assumptions rather than of the data on which the computations are based.
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- 1965
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16. Crustal stress research: Highlights of the Fall AGU Session
- Author
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Bezalel C. Haimson
- Subjects
Stress (mechanics) ,Focal mechanism ,QUIET ,General Earth and Planetary Sciences ,In situ stress ,Horizontal stress ,Crustal stress ,Geology ,Seismology - Abstract
An interpretive map of the orientation of minimum horizontal stress for the contiguous United States, based on in situ stress measurements, geological data, and earthquake focal mechanism solutions, indicated that the state of stress within the plate is not uniform. The tectonically active western United States was shown to possess a complicated stress pattern, but even in the relatively quiet eastern and central parts of the country, several major variations in orientation of stress were apparent. A new study, based on measurements in North America, Africa, and Australia, revealed that, on the average, maximum sheer stress increases linearly with depth to at least 5 km, with no indication of leveling off.
- Published
- 1980
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17. Focal mechanisms and the state of stress on the San Andreas Fault in southern California
- Author
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Lucile M. Jones
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Atmospheric Science ,Soil Science ,Aquatic Science ,Elastic-rebound theory ,Fault (geology) ,Oceanography ,Stress (mechanics) ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,P-wave ,Horizontal stress ,Earth-Surface Processes ,Water Science and Technology ,geography ,Focal mechanism ,geography.geographical_feature_category ,Ecology ,San andreas fault ,Paleontology ,Forestry ,Overburden pressure ,Geophysics ,Space and Planetary Science ,human activities ,Seismology ,Geology - Abstract
Focal mechanisms have been determined from P wave first motion polarities for 138 small to moderate (2.6 ≤ M ≤ 4.3) earthquakes that occurred within 10 km of the surface trace of the San Andreas fault in southern California between 1978 and 1985. On the basis of these mechanisms the southern San Andreas fault has been divided into five segments with different stress regimes. Earthquakes in the Fort Tejon segment show oblique reverse sup on east-west and northwest striking faults. The Mojave segment has earthquakes with oblique reverse and right-lateral strikesup motion on northwest strikes. The San Bernardino segment has normal faulting earthquakes on north-south striking planes, while the Banning segment has reverse, strike-sup, and normal faulting events all occurring in the same area. The earthquakes in the Indio segment show strike-slip and oblique normal faulting on northwest to north-south striking planes. These focal mechanism data have been inverted to determine how the stresses acting on the San Andreas fault in southern California vary with position along strike of the fault. One of the principal stresses is vertical in all of the regions. The vertical stress is the minimum principal stress in Fort Tejon and Mojave, the intermediate principal stress in Banning and Indio, and the maximum principal stress in San Bernardino. The orientations of the horizontal principal stresses also vary between the regions. The trend of the maximum horizontal stress rotates over 35°, from N15°W at Fort Tejon to N20° at Indio. Except for the San Bernardino segment, the trend of the maximum horizontal stress is at a constant angle of about 65° to the local strike of the San Andreas fault, implying a weak fault. The largest change in the present stress state occurs at the end of the rupture zone of the 1857 Fort Tejon earthquake. It appears that the 1857 rupture ended when it propagated into an area of low stress amplitude, possibly caused by the 15° angle between the strikes of the San Jacinto and San Andreas faults. The strong correlation between present state of stress and segmentation in previous earthquakes suggests that the stress state is important in controlling rupture propagation.
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- 1988
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18. Results of the multiwell experiment in situ stresses, natural fractures, and other geological controls on reservoirs
- Author
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Paul T. Branagan, David A. Northrop, Lawrence W. Teufel, Norman R. Warpinski, Allan R. Sattler, and John C. Lorenz
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Stress field ,Permeability (earth sciences) ,Natural gas ,business.industry ,Permeability measurements ,General Earth and Planetary Sciences ,Geotechnical engineering ,Natural fracture ,Horizontal stress ,Petrology ,Anisotropy ,business ,Geology - Abstract
Hundreds of millions of cubic meters of natural gas are locked up in low-permeability, natural gas reservoirs. The Multiwell Experiment (MWX) was designed to characterize such reservoirs, typical of much of the western United States, and to assess and develop a technology for the production of this unconventional resource. Flow-rate tests of the MWX reservoirs indicate a system permeability that is several orders of magnitude higher than laboratory permeability measurements made on matrix-rock sandstones. This enhanced permeability is caused by natural fractures. The single set of fractures present in the reservoirs provides a significant permeability anisotropy that is aligned with the maximum in situ horizontal stress. Hydraulic fractures therefore form parallel to the natural fractures and are consequently an inefficient mechanism for stimulation. Successful stimulation may be possible by perturbing the local stress field with a large hydraulic fracture in one well so that a second hydraulic fracture in an offset well propagates transverse to the natural fracture permeability trend.
- Published
- 1988
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19. World stress map: International workshop on the European contribution
- Author
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Birgit Müller, Larry Mastin, and Mary Lou Zoback
- Subjects
Plate tectonics ,San andreas fault ,Near critical ,General Earth and Planetary Sciences ,Crust ,Crustal stress ,Seismic risk ,Horizontal stress ,Geology ,Seismology - Abstract
Ever since the recognition of plate tectonics as a major Earth process, maps of the orientation of stress in Earth's crust have given us one of the most direct clues to the forces that drive plate movements. We now know from these maps that stress orientations are consistent on a regional scale, that the boundaries between provinces of uniform stress direction generally coincide with major physiographic and structural boundaries, and that for many regions the orientation of the maximum compressive horizontal stress generally coincides with directions of plate motion [e.g., Zoback and Zoback, 1989]. On a regional scale, maps of crustal stress have provided striking evidence of the low strength of plate margin at the San Andreas Fault in California [M. D. Zoback et al, 1988]. In industry, maps of stress orientations have been used to plan secondary recovery projects for oil and gas [Bell and Babcock, 1986] and evaluate seismic risk near critical facilities [e.g., Stock et al., 1985].
- Published
- 1989
- Full Text
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20. In situ stress determination by hydrofracturing: A fracture mechanics approach
- Author
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Ahmed S. Abou-Sayed, C. E. Brechtel, and Rodney J. Clifton
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Atmospheric Science ,Ecology ,Shale gas ,West virginia ,Paleontology ,Soil Science ,Forestry ,Fracture mechanics ,In situ stress ,Aquatic Science ,Oceanography ,Geophysics ,Hydraulic fracturing ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Geotechnical engineering ,Comminution ,Horizontal stress ,Oil shale ,Geology ,Earth-Surface Processes ,Water Science and Technology - Abstract
The in situ stress field was determined at a depth of 837 m (2745 feet) in Devonian Shale ('gray' shale) within the Rome Basin in West Virginia. Logging data and laboratory observations of core samples reveal vertical cracks oriented at N50/sup 0/-60/sup 0/E. Because of these cracks and their preferred orientation a new approach based on fracture mechanics concepts is used to evaluate the in situ stresses from the field and laboratory data. The resulting prediciton of the maximum horizontal stress (sigma/sub H/max) is compared to the maximum horizontal stress predicted by Haimson and Fairhurst's (1967) method; the latter method appears to overestimate the value of this stress component because the effect of loading the faces of any preexisting crack is neglected.
- Published
- 1978
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21. Stress directions in eastern North America determined to 4.5 km from borehole elongation measurements
- Author
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John W. Cox and Richard A. Plumb
- Subjects
Atmospheric Science ,Ecology ,Borehole ,Paleontology ,Soil Science ,Forestry ,Aquatic Science ,Structural basin ,Oceanography ,Stress (mechanics) ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Elongation ,Horizontal stress ,Geomorphology ,Directional analysis ,Seismology ,Geology ,Earth-Surface Processes ,Water Science and Technology - Abstract
Stress directions have been determined to depths of 4.5 km in eastern North America from borehole elongation measured by dipmeter calipers in 47 wells. The average maximum horizontal stress directions are eastern Canada, N54°E ± 7°; Appalachian Basin, N58°E ± 8°; and the Illinois Basin, N89°W ± 5°. Stress directions determined for the Illinois and Appalachian basins are in agreement with published interpretations from hydraulic fractures and earthquake fault plane solutions. New results from eastern Canada and the Appalachian Basin show that stress directions are everywhere consistent with the Midcontinent stress province. These data suggest that the maximum horizontal stress does not rotate from the ENE Midcontinent trend to NW near the Atlantic coast. A directional analysis of hydraulic fractures, petal-centerline fractures, and natural fractures from the Appalachian Basin shows that borehole elongation is systematically aligned perpendicular to the directions of hydraulic fractures, centerline fractures, and northeast striking natural fractures but is not systematically aligned with northwest striking natural fractures. These observations indicate that borehole elongations provide reliable stress orientations.
- Published
- 1987
- Full Text
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