Time-dependent brittle creep as a mechanism for time-delayed wellbore failure

Schoenball, Martin; Sahara, David P.; Köhl, Thomas

doi:10.1016/j.ijrmms.2014.05.012

Cited by 48 publications

(17 citation statements)

References 38 publications

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“…Drilling and production operations, such as hydrofracturing jobs in shale reservoirs, usually result in large disturbances of the reservoir formations and are often associated with time-dependent changes in the structure, mechanical, and transport properties of the rocks. Thus, over time, fracture apertures evolve (Kassis & Sondergeld, 2010;Polak et al, 2003), production declines (Patzek et al, 2013), subsidence sometimes occurs (Chang et al, 2014), wellbore stability may be affected (Schoenball et al, 2014), and, in some cases, the altered effective stresses may trigger induced seismicity (Davies et al, 2013;Ellsworth, 2013). Poroelastic deformation is a possible source of time-dependent behavior, as shown for reservoir subsidence (Altmann et al, 2010), wellbore stability (Ghassemi & Zhang, 2004), or induced seismicity (Segall & Lu, 2015), but time dependence may also originate from the inelastic creep within shales.…”

Section: Introductionmentioning

confidence: 99%

Creep Deformation in Vaca Muerta Shale From Nanoindentation to Triaxial Experiments

et al. 2019

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We tested samples cored from the Vaca Muerta shale reservoir using nanoindentation (2 min) and triaxial (12 hr) creep experiments in which confining pressure and differential stresses were <40 MPa. In all cases, we observed transient creep wherein strain increased as the logarithm of time. Creep was always compactional, led to increased moduli, was triggered by changes in either hydrostatic or deviatoric stress, and occurred under loads well below the failure stress. Our results are consistent with yield cap models proposed to describe shear‐enhanced compaction of sandstones and carbonates, assuming that the yield surface depends on strain rate. We compared our results to earlier studies that observed the transition from transient creep to approximately constant strain rate behavior. If short‐term creep can be quantified by a creep modulus, C, and long‐term creep, after a transition time, tc, by a linear viscosity, η, then η = Ctc. Owing to heterogeneity, the local values of Young's and creep moduli, E and C, measured during nanoindentation, varied by several orders of magnitude. Simple averaging of the indentation results overestimated E and C, as compared to their triaxial counterparts. The kinetics of log time creep, which is seen in various materials and loading circumstances, has been represented by a simple conceptual model incorporating the interplay of viscoelastic elements with widely distributed characteristic times. Thus, we argue that log time creep is an emerging phenomenon, independent of the identities of the underlying physical mechanisms.

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Section: Introductionmentioning

confidence: 99%

Creep Deformation in Vaca Muerta Shale From Nanoindentation to Triaxial Experiments

et al. 2019

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“…An analogous model was applied to explain the reduction of fracture aperture in granites subject to hydrothermal dissolution and precipitation (Yasuhara et al, 2011). Subcritical cracking, the primary bond-breaking process for the near-surface rock (Eppes & Keanini, 2017), and brittle creep models have been successfully used to predict delayed failure in a variety of lithologies (Brantut et al, 2012(Brantut et al, , 2013Stefanou & Sulem, 2014) and to simulate borehole spalling and breakout (Schoenball et al, 2014). So far, however, no model accounts for both the effects of chemical reactions on rock stiffness and strength and the effects of fracturing on chemical weathering.…”

Section: Introductionmentioning

confidence: 99%

Mineral Weathering and Bedrock Weakening: Modeling Microscale Bedrock Damage Under Biotite Weathering

et al. 2019

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Bedrock weakening is of wide interest because it influences landscape evolution, chemical weathering, and subsurface hydrology. A longstanding hypothesis states that bedrock weakening is driven by chemical weathering of minerals like biotite, which expand as they weather and create stresses sufficient to fracture rock. We build on recent advances in rock damage mechanics to develop a model for the influence of multimineral chemical weathering on bedrock damage, which is defined as the reduction in bedrock stiffness. We use biotite chemical weathering as an example application of this model to explore how the abundance, aspect ratio, and orientation affect the time‐dependent evolution of bedrock damage during biotite chemical weathering. Our simulations suggest that biotite abundance and aspect ratio have a profound effect on the evolution of bedrock damage during biotite chemical weathering. These characteristics exert particularly strong influences on the timing of the onset of damage, which occurs earlier under higher biotite abundances and smaller biotite aspect ratios. Biotite orientation, by contrast, exerts a relatively weak influence on damage. Our simulations further show that damage development is strongly influenced by the boundary conditions, with damage initiating earlier under laterally confined boundaries than under unconfined boundaries. These simulations suggest that relatively minor differences in biotite populations can drive significant differences in the progression of rock weakening. This highlights the need for observations of biotite abundance, aspect ratio, and orientation at the mineral and field scales and motivates efforts to upscale this microscale model to investigate the evolution of the macroscale fracture network.

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“…The research on the stability of the wellbore in creep formation is mainly in the salt rock stratum and the soft mudstone stratum. Schoenball et al 16 conducted multi-stage loading creep experiments on clay and carbonate-rich shale in unconventional natural gas reservoirs. Infante and Chenevert 13 studied the stress change of salt rock during the wellbore shrinkage process in deep formation.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the variation law of caliper logging data, they established the inversion analysis method of elastic parameters and viscous parameters of salt rock formations. Schoenball et al 16 conducted multi-stage loading creep experiments on clay and carbonate-rich shale in unconventional natural gas reservoirs. Their experiments found that the shale samples have the same creep trend regardless of the loading history.…”

Section: Introductionmentioning

confidence: 99%

Wellbore shrinkage during drilling in methane hydrate reservoirs

Yan

Yang

Yan³

et al. 2019

Energy Science & Engineering

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Methane hydrates as a clean and abundant energy source, have attracted the attention of the world. However, the instability of hydrate reservoirs makes it difficult to drill production wells. After drilling, the creep properties of hydrate reservoir would cause wellbore shrinkage, which will affect the drilling safety. This study is to analysis law of wellbore shrinkage after a hydrate well drilled. The results demonstrate that wellbore shrinkage mainly results from plastic deformation and creep deformation. The largest and smallest values are separately found in the directions of the maximum and minimum horizontal in‐situ stress. With the increase of initial in‐situ stress ratio, wellbore shrinkage linearly rise. Under the condition of low horizontal in‐situ stress ratio, wellbore shrinkage is mainly determined by creep deformation. Under the condition of high horizontal in‐situ stress ratio, wellbore shrinkage commonly depends on plastic deformation and creep deformation. With deepening methane hydrate reservoirs, wellbore shrinkage shows a nonlinear increase. For formations with higher hydrate saturation, larger wellbore shrinkage would occur. The research results can provide a theoretical basis for the selection of drilling method while drilling in hydrate formations.

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Time-dependent brittle creep as a mechanism for time-delayed wellbore failure

Cited by 48 publications

References 38 publications

Creep Deformation in Vaca Muerta Shale From Nanoindentation to Triaxial Experiments

Creep Deformation in Vaca Muerta Shale From Nanoindentation to Triaxial Experiments

Mineral Weathering and Bedrock Weakening: Modeling Microscale Bedrock Damage Under Biotite Weathering

Wellbore shrinkage during drilling in methane hydrate reservoirs

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