Stress and Pore Pressure in Mudrocks Bounding Salt Systems

Nikolinakou, M. A.; Flemings, Peter B.; Heidari, Mahdi; Hudec, Michael R.

doi:10.1007/s00603-018-1540-z

Cited by 10 publications

(12 citation statements)

References 53 publications

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“…A related element of many experimental and numerical model results was bed thinning and lengthening during folding above and adjacent to diapirs (e.g., Lemon, 1985;Davison et al, 1993;Alsop et al, 1995;Alsop, 1996;Schultz-Ela, 2003;Nikolinakou et al, 2018a). This was also the case for experimental-model halokinetic megaflaps (Callot et al, 2016), which are minibasin-scale zones of upturned and thinned strata (Rowan et al, 2016).…”

Section: Salt Stocks/wallsmentioning

confidence: 93%

“…The increase in horizontal stress and decrease in concentric (hoop) stress in the upper parts of diapirs (Fig. 3c) has been invoked to cause radial faulting due to lateral expansion of the diapir, so-called stem push (e.g., Luo et al, 2012;Nikolinakou et al, 2014Nikolinakou et al, , 2017Nikolinakou et al, , 2018aHeidari et al, 2017). Similarly, elevated in situ shear stress resulting from increased pore pressure adjacent to a diapir just above a dipping permeable bed may be great enough to cause shearing of diapir-flanking strata (Heidari et al, 2019).…”

Section: Salt Stocks/wallsmentioning

confidence: 99%

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Folding and fracturing of rocks adjacent to salt diapirs

Rowan

Muñoz

Giles

et al. 2020

Journal of Structural Geology

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Section: Salt Stocks/wallsmentioning

confidence: 93%

Section: Salt Stocks/wallsmentioning

confidence: 99%

Folding and fracturing of rocks adjacent to salt diapirs

Rowan

Muñoz

Giles

et al. 2020

Journal of Structural Geology

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“…Heidari et al. 2019; Nikolinakou, Flemings, et al., 2018). The constitutive formulation does not account for strain softening of faulting.…”

Section: Modelling Uncertainties and Limitationsmentioning

confidence: 99%

“…2008; Nikolinakou et al. 2018). Poromechanical (geomechanical) models, in particular, incorporate coupled porous fluid flow and the full stress tensor in modelling the compression behaviour and strength of sediments.…”

Section: Introductionmentioning

confidence: 99%

Geologically constrained evolutionary geomechanical modelling of diapir and basin evolution: A case study from the Tarfaya basin, West African coast

Hooghvorst

Nikolinakou

Harrold³

et al. 2021

Basin Research

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We systematically incorporate burial history, sea floor geometry and tectonic loads from a sequential kinematic restoration model into a 2D evolutionary geomechanical model that simulates the formation of the Sandia salt diapir, Tarfaya basin, NW African Coast. We use a poro-elastoplastic description for the sediment behaviour and a viscoplastic description for the salt. Sedimentation is coupled with salt flow and regional shortening to determine the sediment porosity and strength and to capture the interaction between salt and sediments. We find that temporal and spatial variation in sedimentation rate is a key control on the kinematic evolution of the salt system. Incorporation of sedimentation rates from the kinematic restoration at a location east of Sandia leads to a final geomechanical model geometry very similar to that observed in seismic reflection data. We also find that changes in the variation of shortening rates can significantly affect the present-day stress state above salt. Overall, incorporating kinematic restoration data into evolutionary models provides insights into the key parameters that control the evolution of geologic systems. Furthermore, it enables more realistic evolutionary geomechanical models, which, in turn, provide insights into sediment stress and porosity.

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“…We estimate stresses around a submarine salt body below the Sigsbee Escarpment in Mad Dog Field, deepwater Gulf of Mexico (Figure 8a). The strain and stress states of the rocks in this region can differ significantly from those developed under purely vertical, uniaxial strain because the salt body and the significant topography at the Sigsbee Escarpment significantly affect both the magnitude and the orientation of principal stresses in adjacent rocks (Fredrich et al, 2003; Heidari et al, 2017; Nikolinakou, Flemings, et al, 2018). The magnitude and extent of salt and topography's effects on stresses depend on the mechanical behavior of the rocks.…”

Section: Geological Applicationsmentioning

confidence: 99%

Modified Cam‐Clay Model for Large Stress Ranges and Its Predictions for Geological and Drilling Processes

2020

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We modify the Modified Cam-Clay (MCC) model for large stress ranges encountered in geological applications. The MCC model assumes that the friction angle (ϕ) and the slope of the compression curve (λ) of a mudrock are constant and thus predicts constant values for the lateral effective stress ratio under uniaxial, vertical strain (K 0) and undrained strength ratio (S u σ′ v). However, experimental work shows that λ, ϕ, and S u σ′ v decrease and K 0 increases substantially with stress over large stress ranges (e.g., up to 100 MPa). We incorporate the stress dependency of λ and ϕ into the MCC model and use the new model to predict S u σ′ v and K 0 ratios. The modified model, with only one additional parameter, successfully predicts the stress dependency of these ratios. We encode the modified model and use it for finite-element analysis of a salt basin in the deepwater Gulf of Mexico. The stresses that the new model predicts around salt differ significantly from those predicted using the original model. We incorporate the stress dependency of the friction angle into the analytical models developed for critical tapers, wellbore drilling, and the stability of submarine channel levees. We show that the decrease of the friction angle with stress (1) results in a concave surface for critical wedges, (2) shifts the drilling window to higher mud weights and makes it narrower for a vertical wellbore, and (3) causes deep-seated failure of submarine channel levees at lower angles. Our study could improve in situ stress and pore pressure estimation, wellbore drilling, and quantitative understanding of geological processes.

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Stress and Pore Pressure in Mudrocks Bounding Salt Systems

Cited by 10 publications

References 53 publications

Folding and fracturing of rocks adjacent to salt diapirs

Folding and fracturing of rocks adjacent to salt diapirs

Geologically constrained evolutionary geomechanical modelling of diapir and basin evolution: A case study from the Tarfaya basin, West African coast

Modified Cam‐Clay Model for Large Stress Ranges and Its Predictions for Geological and Drilling Processes

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