A model of fluid expulsion from compacting tight sedimentary rocks based on the Toggle-Switch algorithm

Wangen, Magnus

doi:10.1016/j.acags.2022.100079

Cited by 3 publications

(3 citation statements)

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“…Dynamic fluid transport has been numerically modelled with cellular automata in several studies (Miller & Nur, 2000;Bons and van Milligen, 2001;de Riese et al 2020;Hooker & Fisher, 2021;Wangen, 2022). Miller and Nur (2000) and Bons and van Milligen (2001) both showed that fluid flow self-organizes as soon as a critical state is reached, which activates hydrofracturecontrolled fluid flow as a ballistic fluid transport mode, resulting in power-law distributed frequencies of hydrofracture sizes.…”

Section: B5 Dynamics Of Crustal-scale Flow In Hydrofracturesmentioning

confidence: 99%

“…Miller and Nur (2000) and Bons and van Milligen (2001) both showed that fluid flow self-organizes as soon as a critical state is reached, which activates hydrofracturecontrolled fluid flow as a ballistic fluid transport mode, resulting in power-law distributed frequencies of hydrofracture sizes. Wangen (2022) utilized the same approach to model fluid expulsion from compacting sediments. In reality, transport of fluid through the crust is never exclusively diffusive Darcian, or intermittent hydrofracture flow only, but rather a combination of the two end members (e.g.…”

Section: B5 Dynamics Of Crustal-scale Flow In Hydrofracturesmentioning

confidence: 99%

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A review of natural hydrofractures in rocks

et al. 2022

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Hydrofractures, or hydraulic fractures, are fractures where a significantly elevated fluid pressure played a role in their formation. Natural hydrofractures are abundant in rocks and are often preserved as magmatic dykes or sills, and mineral-filled fractures or mineral veins. However, we focus on the formation and evolution of non-igneous hydrofractures. Here we review the basic theory of the role of fluid pressure in rock failure, showing that both Terzaghi’s and Biot’s theories can be reconciled if the appropriate boundary conditions are considered. We next discuss the propagation of hydrofractures after initial failure, where networks of hydrofractures may form or hydrofractures may ascend through the crust as mobile hydrofractures. As fractures can form as a result of both tectonic stresses and an elevated fluid pressure, we address the question of how to ascertain whether a fracture is a hydrofracture. We argue that extensional or dilational fractures that formed below c. 2–3 km depth are, under normal circumstances, hydrofractures, but at shallower depth they may, but must not be hydrofractures. Since veins and breccias are often the products of hydrofractures that are left in the geological record, we discuss these and critically assess which vein structures can, and which do not necessarily, indicate hydrofracturing. Hydrofracturing can suddenly and locally change the permeability in a rock by providing new fluid pathways. This can lead to highly dynamic self-organization of crustal-scale fluid flow.

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Section: B5 Dynamics Of Crustal-scale Flow In Hydrofracturesmentioning

confidence: 99%

Section: B5 Dynamics Of Crustal-scale Flow In Hydrofracturesmentioning

confidence: 99%

A review of natural hydrofractures in rocks

et al. 2022

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“…In the work of Maghous et al [21], a relatively better version of activation-deactivation is applied to model sedimentary basin growth by modifying the solid and fluid density within the mesh elements. Wangen et al [22] made use of toggle switch cellular automation method to model fluid expulsion along with local microfracturing and redistribution of pore fluid. In this context, the numerical model we propose in this work is more sophisticated and accurate, as we get rid of explicit bookkeeping of the boundary location and no explicit activation/deactivation of any region or modifications of material properties in the mesh elements is needed.…”

Section: Introductionmentioning

confidence: 99%

A Novel Phase-Field Based Formulation of Interface Evolution during Mechanical Compaction of Sedimentary Basins

Bhagat¹,

Jin²,

Rudraraju³

2022

Preprint

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A novel phase-field method based numerical approach to modeling the compaction process of sedi- ments is presented. Water-logged rock or soil sediments are deposited on the water basins over time and the increasing volume of the sediment compacts under its own weight and external pressure. Coupled evolution of mass conservation, Darcy flow, and the viscoelastic constitutive response, in conjunction with the evolution of porosity and permeability, make this problem highly non-linear and involve moving boundaries. We adopt a phase-field approach to represent the moving sediment interface, and the underlying multiphasic model permits for studying compaction in dynamically evolving sediments. This approach does not necessitate a change of domain sizes as is the case of existing traditional models of sedimentation but rather treats sedimentation growth as a problem of interface motion. We first model a classical compaction problem in 1D to compare with existing results in the literature, and then extend the framework to 2D to model the compaction process taking place under the influence of gravity. The model is then extensively applied to understand the effect of the sediment initial state and the sediment material properties on the compaction process and its spatiotemporal evolution. Lastly, a strong validation of our phase-field treatment results against predictions from traditional methods of solving open boundary sediment compaction problems, and a good agreement between the conventional understanding and the numerical predictions of porosity dependence on the fluid pore pressure for various cases of geological interest, are used to demonstrate the applicability and scalability of this novel numerical framework to model more advanced sediment compaction problems and geometries.

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