Two-phase fluid-flow modeling in a dilatant crack-like pathway

Rozhko, Alexander Y.

doi:10.1016/j.petrol.2016.08.018

Cited by 16 publications

(27 citation statements)

References 47 publications

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“…(A) Partially saturated crack (modified after: Rozhko ), plane‐strain (2D) approximation. The wetting fluid phase symmetrically occupies the crack tips while the non‐wetting phase is in the centre.…”

Section: Rock Physics Modelmentioning

confidence: 99%

“…An analytical solution describing equilibrium stresses and displacements around partially saturated cracks can be found in (Rozhko ). The half‐opening of the crack aperture at a given contact line location is calculated as follows (Rozhko ):

\begin{matrix} true \\ right w_{a} & = & left \frac{b}{p_{cl}} true(p_{cl} + σ + p_{we} \\ left + ((), \frac{π - 2 β - 2 \cot (β) \ln [cos (β)]}{π}) p_{cap} true) prefixsin (β) . \end{matrix}

…”

Section: Rock Physics Modelmentioning

confidence: 99%

“…The capillary pressure is calculated using equation and the Laplace equation,

p_{cap} = \frac{γ \cos (θ)}{w_{a}}

, as follows (Rozhko ):

\begin{matrix} true \\ right p_{cap} & = & left \frac{π}{4} (p_{cl} + σ + p_{we}) \\ left \times \frac{1 - \sqrt{1 - 8 p_{cl} \frac{γ \cos false(θ false)}{π b} \frac{false(β + \cot false(β false) \ln false[prefixcos false(β false) false] - π / 2 false)}{{false(p_{cl} + σ + p_{we} false)}^{2} prefixsin (β)}}}{β + \cot false(β false) \ln false[prefixcos false(β false) false] - π / 2}, \end{matrix}

where p cl is the crack closure pressure, calculated as (Rozhko ):

p_{cl} = \frac{b E}{2 a (1 - v^{2})},

where E and v are Young's modulus and Poisson's ratio of the rock around a crack. The angle β in equations and defines the location of the contact line:

cos false(β false) = \frac{c}{a} .

…”

Section: Rock Physics Modelmentioning

confidence: 99%

“…The total volume of partially saturated crack is calculated as (Rozhko ):

V_{tot} = π a b (1 + \frac{σ + p_{we} + (1 + \frac{sin (2 β) - 2 β}{π}) p_{cap}}{p_{cl}}) .

…”

Section: Rock Physics Modelmentioning

confidence: 99%

“…The volume of the wetting fluid inside the partially saturated crack is calculated as (Rozhko ):

\begin{matrix} true \\ right {\overset{V}{true}}_{we} & = & left π a b ((), 1 + \frac{σ + p_{we} + p_{cap} ((), 1 + \frac{4}{π} ([], \frac{β sin false(2 β false) - β^{2} + 2 co s^{2} false(β false) \ln false[\cos (β) false]}{2 β - sin (2 β)}))}{p_{cl}}) \\ left \times \frac{false(2 β - \sin false(2 β false) false)}{π} . \end{matrix}

…”

Section: Rock Physics Modelmentioning

confidence: 99%

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Contact line friction and surface tension effects on seismic attenuation and effective bulk moduli in rock with a partially saturated crack

Rozhko

Bauer

2018

Geophysical Prospecting

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The effect of surface phenomena occurring at the interfaces between immiscible fluids and a solid on the seismic attributes of partially saturated rocks has not yet been fully studied. Meanwhile, over the past two decades considerable progress has been made in the physics of wetting to understand effects such as contact line friction, contact line pinning, contact angle hysteresis, and equilibrium contact angle. In this paper, we developed a new rock physics model considering the aforementioned effects on seismic properties of the rock with a partially saturated plane‐strain crack. We demonstrated that for small wave‐induced stress perturbations, the contact line of the interface meniscus will remain pinned, while the meniscus will bulge and change its shape through the change of the contact angles. When the stress perturbation is larger than a critical value, the contact line will move with advancing or receding contact angle depending on the direction of contact line motion. A critical stress perturbation predicted by our model can be in the range of ∼102−104 Pa, that is typical for linear seismic waves. Our model predicts strong seismic attenuation in the case when the contact line is moving. When the contact line is pinned, the attenuation is negligibly small. Seismic attenuation is associated with the hysteresis of loading and unloading bulk moduli, predicted by our model. The hysteresis is large when the contact line is moving and negligibly small when the contact line is pinned. Furthermore, we demonstrate that the bulk modulus of the rock with a partially saturated crack depends also on the surface tension and on the contact angle hysteresis. These parameters are typically neglected during calculation of the effecting fluid moduli by applying different averaging techniques. We demonstrate that contact line friction may be a dominant seismic attenuation mechanism in the low frequency limit (<∼10 Hz) when capillary forces dominate over viscous forces during wave‐induced two‐phase fluid flow.

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Section: Rock Physics Modelmentioning

confidence: 99%

\begin{matrix} true \\ right w_{a} & = & left \frac{b}{p_{cl}} true(p_{cl} + σ + p_{we} \\ left + ((), \frac{π - 2 β - 2 \cot (β) \ln [cos (β)]}{π}) p_{cap} true) prefixsin (β) . \end{matrix}

…”

Section: Rock Physics Modelmentioning

confidence: 99%

“…The capillary pressure is calculated using equation and the Laplace equation,

p_{cap} = \frac{γ \cos (θ)}{w_{a}}

, as follows (Rozhko ):

\begin{matrix} true \\ right p_{cap} & = & left \frac{π}{4} (p_{cl} + σ + p_{we}) \\ left \times \frac{1 - \sqrt{1 - 8 p_{cl} \frac{γ \cos false(θ false)}{π b} \frac{false(β + \cot false(β false) \ln false[prefixcos false(β false) false] - π / 2 false)}{{false(p_{cl} + σ + p_{we} false)}^{2} prefixsin (β)}}}{β + \cot false(β false) \ln false[prefixcos false(β false) false] - π / 2}, \end{matrix}

where p cl is the crack closure pressure, calculated as (Rozhko ):

p_{cl} = \frac{b E}{2 a (1 - v^{2})},

where E and v are Young's modulus and Poisson's ratio of the rock around a crack. The angle β in equations and defines the location of the contact line:

cos false(β false) = \frac{c}{a} .

…”

Section: Rock Physics Modelmentioning

confidence: 99%

“…The total volume of partially saturated crack is calculated as (Rozhko ):

V_{tot} = π a b (1 + \frac{σ + p_{we} + (1 + \frac{sin (2 β) - 2 β}{π}) p_{cap}}{p_{cl}}) .

…”

Section: Rock Physics Modelmentioning

confidence: 99%

“…The volume of the wetting fluid inside the partially saturated crack is calculated as (Rozhko ):

\begin{matrix} true \\ right {\overset{V}{true}}_{we} & = & left π a b ((), 1 + \frac{σ + p_{we} + p_{cap} ((), 1 + \frac{4}{π} ([], \frac{β sin false(2 β false) - β^{2} + 2 co s^{2} false(β false) \ln false[\cos (β) false]}{2 β - sin (2 β)}))}{p_{cl}}) \\ left \times \frac{false(2 β - \sin false(2 β false) false)}{π} . \end{matrix}

…”

Section: Rock Physics Modelmentioning

confidence: 99%

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Contact line friction and surface tension effects on seismic attenuation and effective bulk moduli in rock with a partially saturated crack

Rozhko

Bauer

2018

Geophysical Prospecting

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Modeling of natural fracture initiation and propagation in basin sedimentation context

2017

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During sedimentation, buried rocks are subjected to an increase in vertical stress. This increase leads to a decrease of porosity that is commonly called mechanical compaction. Indeed, the mechanical compaction depending on its rate and on the permeability of the burden rocks can induce significant overpressures. Thus, a competition is initiated between the dissipation of fluid overpressure and sedimentation rate and may result in fracture initiation. The present study deals with the initiation and propagation of natural fracture in sealing formations. A particular emphasis is put on mode I fracture propagation. An analytical solution of the pressure and stresses in a sealing formation is proposed under sedimentation by superposing two problems of poroelasticity. This analytical solution and a damage criterion are used to predict the initiation and propagation of the fracture. The damage parameter affects both the mechanical and hydraulic openings of the fracture, and the flow in the fracture is described by Poseuille's law. The fracture propagation and growth are studied by numerical simulations based on a finite element code dedicated to fractured porous media called Porofis. Interactions between hydraulic and mechanical processes are also studied, and a sensitivity study is carried out in order to find the most important parameters involved in natural fracturing under sedimentation.

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Water, CO2 and Argon Permeabilities of Intact and Fractured Shale Cores Under Stress

Noort

Yarushina

2018

Rock Mech Rock Eng

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As shale is the caprock over many reservoirs targeted for CO 2 storage, shale permeability to CO 2 has become an important concern. Measurements of this permeability need to be performed under in-situ conditions, with realistic temperatures, confining pressures and fluid pressures, and the effects of variables such as pressure, temperature, and shale moisture content need to be thoroughly addressed. Furthermore, the exposure of wet shale to dry CO 2 can lead to, for example, dehydration and two-phase flow, that in turn affect permeability. This paper reports shale permeability measurements performed on two shale core plugs from Svalbard, under in-situ pressure and temperature conditions relevant for CO 2 storage, using argon, CO 2, and water as the permeate, and using both transient pulse and constant flow techniques. Permeability was found to be dependent mainly on effective confining pressure and on shale moisture content. The following was observed: (1) permeability decreased with increasing effective confining pressure; (2) permeability to water was lower than permeability to Ar or CO 2 ; (3) shale moisture content had a strong inhibiting effect on the flow of Ar and CO 2 ; (4) when a high CO 2-flow was applied to a shale sample containing a hydrous pore fluid, a breakthrough effect occurred; and (5) in the presence of pore water, compaction creep can occur, causing a permanent decrease in permeability.

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Two-phase fluid-flow modeling in a dilatant crack-like pathway

Cited by 16 publications

References 47 publications

Contact line friction and surface tension effects on seismic attenuation and effective bulk moduli in rock with a partially saturated crack

Contact line friction and surface tension effects on seismic attenuation and effective bulk moduli in rock with a partially saturated crack

Modeling of natural fracture initiation and propagation in basin sedimentation context

Water, CO2 and Argon Permeabilities of Intact and Fractured Shale Cores Under Stress

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