Modelling of Stress Refraction in Sediments Around the Peace River Arch, western Canada

Bell, J. S.; Lloyd, P F

doi:10.4095/126688

Cited by 11 publications

(7 citation statements)

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“…The predicted stress trajectory plot of Figure 7b is remarkably similar to the horizontal stress trajectory plot constructed for the western Canadian Basin breakout data by Bell and Babcock [1986, Figure 6]. In particular, the generally NE-SW trending fitted trajectories tend to refract around subsurface basement arches in the basin (see Bell and Lloyd [1989] for details).…”

Section: Stress Trajectory Mapssupporting

confidence: 74%

Smoothing and extrapolation of crustal stress orientation measurements

Hansen¹,

Mount²

1990

J. Geophys. Res.

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The theory and mechanics of a statistical smoothing algorithm for estimating stress fields based on observed data are described. Incorporated into the algorithm are tunable parameters which allow the user to adjust the smoothness and fidelity of the fitted stress field. In addition, the user has the option of using robustness weights, or to weight the predicted stress field by assigning quality ranks to each data point. Fitted stress fields can be displayed as either a gridded map (axes of maximum, or minimum, horizontal stress are shown as short bars located at each point in an evenly spaced grid), or as a stress trajectory map. Examples of predicted stress fields for southern California and western Canada, based on borehole elongation data, are displayed as stress trajectory maps. A predicted paleostress field for the Spanish Peaks intrusion complex in Colorado, based on vertical dike orientations, is displayed as a gridded map. The smoothing algorithm is not limited to the analysis of stress orientation data. Any data consisting of a set of undirected lines measured at discrete locations are appropriate for input; possible candidates include strain data, mineral or intersection lineations, and lineaments.

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Section: Stress Trajectory Mapssupporting

confidence: 74%

Smoothing and extrapolation of crustal stress orientation measurements

Hansen¹,

Mount²

1990

J. Geophys. Res.

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“…reported for the Peace River Arch in Alberta (Adams and Bell, 1991;Bell and Lloyd, 1989;Fordjor et al, 1983). Potential stress rotation is confirmed by several numerical studies (Bell and Lloyd, 1989;Grünthal and Stromeyer, 1992;Mantovani et al, 2000;Marotta et al, 2002;Spann et al, 1994;Tommasi et al, 1995;Zhang et al, 1994).…”

Section: Strength Contrastsupporting

confidence: 64%

Stress rotation – The impact and interaction of rock stiffness and faults

Reiter¹

2020

Preprint

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Abstract. It has been assumed, that the maximum compressive horizontal stress (SHmax) orientation in the upper crust is governed on a regional scale by the same forces that drive plate motion. However, several regions are identified, where stress orientation deviates from the expected orientation due to plate boundary forces (first order stress sources), or the plate wide pattern. In some of this regions a gradual rotation of the SHmax orientation has been observed. Several second and third order stress sources have been identified, which may explain stress rotation in the upper crust. For example lateral heterogeneities in the crust, such as density, petrophysical or petrothermal properties and discontinuities, like faults are identified as potential candidates to cause lateral stress rotations. To investigate several of the candidates, generic geomechanical numerical models are utilized. These models consist of up to five different units, oriented by an angle of 60° to the direction of contraction. These units have variable elastic material properties, such as Young's modulus, Poisson ratio and density. Furthermore, the units can be separated by contact surfaces that allow them so slide along these faults, depending on a selected coefficient of friction. The model results indicate, that a density contrast or the variation of the Poisson's ratio alone sparsely rotates the horizontal stress orientation (≦ 17°). Conversely, a contrast of the Young's modulus allows significant stress rotations in the order of up to 78°; not only areas in the vicinity of the material transition are affected by that stress rotation. Stress rotation clearly decreases for the same stiffness contrast, when the units are separated by low friction discontinuities (19°). Low friction discontinuities in homogeneous models do not change the stress pattern at all, away from the fault; the stress pattern is nearly identical to a model without any active faults. This indicates that material contrasts are capable of producing significant stress rotation for larger areas in the crust. Active faults that separates such material contrasts have the opposite effect, they rather compensate stress rotations.

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“…The north-westem part of Jutland is an area with severe salt tectonics (Madirazza et al, 1990), which may cause stress reorientation. This stress reorientation may either be due to lateral differences in the elastic parameters because of tangential stress orientations outside the salt dome (Schneider, 1985;Bell and Lloyd, 1989), or to vertical doming which results in a local radial stress pattern (Teufel and Farell, 1990). The Skive-2 well is situated on the northern flank of an oval salt pillow (Madirazza et al, 1990) whereas the SH orientation in the Thisted-3 well is parallels the salt pillow and thus does not fit their results.…”

Section: Downhole Variation Of Shmentioning

confidence: 99%

In situ stress determination from breakouts in the Tornquist Fan, Denmark

1996

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The Tornquist Fan, a fan‐shaped region in Denmark and Western Baltic, is situated in the transition zone between the Western and Northern European Stress Provinces. Breakout data from 20 wells (0.3–3.6 km) were analysed. The fan can be divided into three stress provinces: (i) The area south of the Rømø Fracture Zone is part of the Western European Stress Province and has NNW‐SSE orientation of the maximum horizontal stress, (ii) The sediment cover in the Nonvegian‐Danish Basin is dominated by ENE‐WSW orientated maximum horizontal stress, (iii) The maximum horizontal stress is sub‐parallel to the strike of the Sorgenfrei‐Tornquist Zone. Deviations from the regional stress field were observed in wells close to faults and salt diapirs. In wells south of the Sorgenfrei‐Tornquist Zone, breakout occurrence decreases with increasing age of the stratigraphic units. The downhole breakout distribution seems to correlate with lithology and thickness of the sediment layer.

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Modelling of Stress Refraction in Sediments Around the Peace River Arch, western Canada

Cited by 11 publications

References 0 publications

Smoothing and extrapolation of crustal stress orientation measurements

Smoothing and extrapolation of crustal stress orientation measurements

Stress rotation – The impact and interaction of rock stiffness and faults

In situ stress determination from breakouts in the Tornquist Fan, Denmark

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