An experimental study of the flow of gas along synthetic faults of varying orientation to the stress field: Implications for performance assessment of radioactive waste disposal

Cuss, R.J.; Harrington, J.F.; Noy, D.J.; Sathar, Shanvas; Norris, Simon

doi:10.1002/2014jb011333

Cited by 15 publications

(10 citation statements)

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“…It was seen in test ASR_BigCCS_01 that flow reduced during the first step of reloading, possibly as a result of shear. Fracture transmissivity was seen to reduce in OPA as a result of shear for a planed fracture (Cuss et al 2009(Cuss et al , 2011 and for a realistic fracture Cuss et al , 2015. , showed that shear reduced fracture transmissivity by approximately one order of magnitude.…”

Section: Discussionmentioning

confidence: 92%

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Cyclic loading of an idealized clay‐filled fault: comparing hydraulic flow in two clay gouges

et al. 2016

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faulting/fracturing in the same basin will have formed during the depletion of the reservoir. 39Therefore in many geological settings both natural and induced discontinuities will have 40 formed. 41Fluid flow in argillaceous materials, whether through the bulk rock or along discontinuities, 42is closely related to the mechanical state of the caprock. In particular, the role of faults and 43 fractures as potential conduits or barriers to fluid flow is likely to be of critical importance to 44 seal integrity in Carbon Capture and Storage (CCS) sites. In addition, recent studies [Zoback 45 & Gorelick, 2012] and on-going developments relating to induced seismicity [Green, et al. 46 2011] in other industries have also highlighted the importance of a thorough understanding of 47 the potential for, and controls on, fault reactivation behavior. 57Faulted geological settings are complex systems that are borne out of multiple episodes of 58 deformation, in the form of faulting, subsidence and exhumation, and altered stress regimes. 59This means that faults cannot be viewed as static features over geological time. Nor can they 60 be considered static on CO 2 injection time scales, as complex pore-pressure histories and 61 chemical alteration-driven deformation may also have an impact on caprock systems. As 62 such, time is a significant factor in fault sealing. 63On the long time-scales of interest in CCS, cross-reservoir fluid migration may lead to 64 changes in stress-state long after injection ceases. The response of new or previously-sealed 65 discontinuities exposed to these dynamic conditions, may be significant. Noy et al. [2012] 66 demonstrated that pore-pressure perturbations, resulting from the injection of CO 2 , may 67 persist for significant periods (~300 years) after the injection phase. These perturbations are 68 likely to be particularly large in magnitude within the immediate vicinity of injection, but are 69 also demonstrably of concern 'a considerable distance outside the CO 2 footprint at the end of under an elevated pore-pressure condition, (ii) critically oriented faults with the potential for 74 reactivation (as compared to those far from critically stressed), or faulting with the potential 75 for infrequent but significant seismicity. 76Additionally, both near-and far-field discontinuities may be exposed to a range of changing 77 fluid chemistries during the evolution of a storage site, from CO 2 -rich fluids to the migration 78 of brines at the periphery of the pressure pulse. In contrast to reservoir rocks, the 79 phenomenon of clay swelling is of major importance to the sealing behavior of argillaceous 80 cap-rocks [Horseman et al., 2005; Tsang et al., 2005], with the potential to notably affect 81 transmissivity of discontinuities. CO 2 has been shown to markedly impact on the swelling 82 properties of clays [Espinoza & Santamaria, 2012], but there is a paucity of data relating to 83 the impact on shale swelling properties and, in particular, the potential effects for fault 84 seal...

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Section: Discussionmentioning

confidence: 92%

“…, ) and for a realistic fracture (Cuss & Harrington ; Cuss et al . , ). Cuss & Harrington (), Cuss et al .…”

Section: Discussionmentioning

confidence: 99%

Cyclic loading of an idealized clay‐filled fault: comparing hydraulic flow in two clay gouges

et al. 2016

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“…Experiments on synthetic fault gouge composed of pure kaolinite found that, although fault orientation does have an effect on gas entry pressure, non-optimally orientated faults can also experience flow (Cuss et al 2015). In addition, reactivation of a fault will not necessarily increase the permeability of the fault plane because in some materials, such as weakly cemented sand, initial dilation and continued shearing will result in the formation of low-porosity/low-permeability material (Bjørlykke et al 2005).…”

Section: Discussionmentioning

confidence: 99%

Carbon dioxide storage in the Captain Sandstone aquifer: determination of in situ stresses and fault-stability analysis

Williams

Fellgett

Quinn

2016

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The Lower Cretaceous Captain Sandstone Member of the Inner Moray Firth has significant potential for the injection and storage of anthropogenic CO 2 in saline aquifer parts of the formation. Pre-existing faults constitute a potential risk to storage security owing to the elevated pore pressures likely to result from large-scale fluid injection. Determination of the regional in situ stresses permits mapping of the stress tensor affecting these faults. Either normal or strike-slip faulting conditions are suggested to be prevalent, with the maximum horizontal stress orientated 33°-213°. Slip-tendency analysis indicates that some fault segments are close to being critically stressed under strike-slip stress conditions, with small pore-pressure perturbations of approximately 1.5 MPa potentially causing reactivation of those faults. Greater pore-pressure increases of approximately 5 MPa would be required to reactivate optimally orientated faults under normal faulting or transitional normal/strike-slip faulting conditions at average reservoir depths. The results provide a useful indication of the fault geometries most susceptible to reactivation under current stress conditions. To account for uncertainty in principal stress magnitudes, high differential stresses have been assumed, providing conservative fault-stability estimates. Detailed geological models and data pertaining to pore pressure, rock mechanics and stress will be required to more accurately investigate fault stability.

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“…The relationship between in situ stress and fluid flow in faults is well established, with critically stressed faults aligned favourably to the stress tensor perceived as being most likely to be hydraulically conductive and posing a greater risk to seal integrity. While this has been shown not to be true in all cases (Laubach et al 2004;Sathar et al 2012;Cuss et al 2015), a number of studies from a variety of settings worldwide (Barton et al 1995;Wiprut & Zoback 2000;Finkbeiner et al 2001;Hennings et al 2012) indicate that it is useful to adopt as a general rule in assessing seal integrity, at least in the absence of evidence regarding specific fault properties. In a study of fluid flow in naturally occurring fractures at the Soultzsous-Forets Hot Dry Rock geothermal site in France, Evans (2005) showed that while all flowing fractures were observed to be critically stressed, a large number of similarly stressed fractures were not hydraulically conductive.…”

Section: Controls On Caprock Integritymentioning

confidence: 99%

Impact of in situ stress and fault reactivation on seal integrity in the East Irish Sea Basin, UK

Williams

Gent

Fellgett

et al. 2018

Marine and Petroleum Geology

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Despite having been affected by several stages of exhumation during the Cretaceous and Cenozoic, the contemporary stress state of the East Irish Sea (EISB) is poorly characterised. As the basin is mature in terms of exploitation of hydrocarbons, future exploration beyond the conventional Sherwood Sandstone Group reservoir (Triassic) necessitates a greater understanding of the in situ stress field, while proposed natural gas storage and carbon sequestration schemes also require detailed stress field information. Using petroleum well data, the in situ stress field of the EISB has been characterised to assess the mechanical seal integrity. A strike-slip stress regime most-likely prevails in the basin, meaning the Maximum Horizontal Stress (SHmax) is the greatest of the principal stresses. Interpretation of stress orientation data suggests that SHmax is oriented 152˚ ± 12˚, consistent with mean stress orientations across the wider region associated with plate boundary forces. Some degree of structural control appears to influence the orientation of SHmax, with orientations locally aligned sub-parallel to major Permo-Triassic basin-bounding faults. Fault reactivation risk is evaluated through modelling the pore pressure increase required to induce failure on pre-existing faults. Vertical faults striking 30˚ from SHmax are optimally-oriented to become reactivated under elevated pore pressure conditions. For any project relying on an element of fault seal for the containment of buoyant fluids at the average reservoir depth of 800 m, pore pressure increase should be less than 3.3 MPa to avoid reactivating pre-existing optimally-oriented faults. Higher pressure increases would be required to initiate reactivation of faults with other orientations. Vertical faults striking perpendicular to SHmax are least likely to become reactivated, and in the absence of halite, seal integrity would instead be limited by caprock strength and capillary-entry pressure. Major faults affecting the basin have been analysed for their slip tendency (ratio of shear to normal stress), which provides an indication of their susceptibility to become reactivated. Although the analysis is limited due to lack of an accurate 3D representation of the fault network, the results suggest that many of the fault orientations observed in the EISB exhibit high slip tendencies, including N-S striking faults to the north and west of the East Deemster Fault, where the SHmax orientation is NW-SE. Faults striking perpendicular to SHmax, such as the Lagman Fault, are least likely to become reactivated due to higher normal stresses that inhibit frictional sliding, while faults striking parallel or very close to SHmax also exhibit low slip tendency as they are not subjected to significant shear stresses.

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An experimental study of the flow of gas along synthetic faults of varying orientation to the stress field: Implications for performance assessment of radioactive waste disposal

Cited by 15 publications

References 15 publications

Cyclic loading of an idealized clay‐filled fault: comparing hydraulic flow in two clay gouges

Cyclic loading of an idealized clay‐filled fault: comparing hydraulic flow in two clay gouges

Carbon dioxide storage in the Captain Sandstone aquifer: determination of in situ stresses and fault-stability analysis

Impact of in situ stress and fault reactivation on seal integrity in the East Irish Sea Basin, UK

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