Deformation of Athabasca oil sand at low effective stresses under varying boundary conditions

Samieh, Ahmed M.; Wong, R.C.K.

doi:10.1139/t97-048

Cited by 38 publications

(15 citation statements)

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“…Because of its shallow depth and the stress paths encountered in the recovery processes, the understand-ing of its geomechanical properties at low effective stress is important for design of the recovery processes. Samieh and Wong (1997) conducted some drained triaxial compression tests on undisturbed Athabasca oil sand specimens at low effective stresses ranging from 5 to 750 kPa. Details of site location, core sampling, specimen preparation, and testing procedures are presented by Samieh (1995).…”

Section: Introductionmentioning

confidence: 97%

“…Details of site location, core sampling, specimen preparation, and testing procedures are presented by Samieh (1995). Samieh and Wong (1997) found that the stress-strain responses observed in drained triaxial compression are dependent on the test boundary conditions and specimen slenderness ratio. Various shear-banding patterns were observed in the sheared specimens.…”

Section: Introductionmentioning

confidence: 99%

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Mobilized strength components of Athabasca oil sand in triaxial compression

Wong¹

1999

Can. Geotech. J.

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Dense uncemented Athabasca oil sand specimens exhibit unusually high peak strength, dilation with severe softening, and residual strength in drained triaxial compression tests. Computer tomography scanning, X-ray imaging, and scanning electron microscopy techniques are used to examine the microstructural features of the sheared specimens, such as interlocked structure, shear-banding pattern, and porosity distributions inside and outside shear bands. The characteristics of these microstructural features are used to explain the macrodeformation responses observed in the triaxial compression tests. Mobilization of strength components derived from interlocked structure, dilation, rolling, and critical state are analyzed for pre-peak, post-peak softening, and residual states.Resumé : Lors d'essais de compression triaxiale drainée, les échantillons de sable bitumineux dense et non cimenté d'Athabasca indiquent une résistance de pic anormalement élevée, un comportement dilatant avec radoucissement sévère et une résistance résiduelle. On a utilisé des techniques de balayage tomographique par ordinateur, d'imagerie aux rayons X et de microscopie électronique à balayage (MEB) pour étudier les propriétés micro-structurales des échantillons cisaillés, comme la structure imbriquée, le motif des bandes de cisaillement, les répartitions de la porosité à l'intérieur et à l'extérieur de ces dernières. On s'est ensuite servi des caractéristiques de ces propriétés microstructurales pour expliquer les réponses en macro-déformation observées lors des essais de compression triaxiale. La mobilisation des composantes de la résistance qui dérivent de la structure imbriquée, de la dilatance, du chevauchement par roulement et de l'état critique a été analysée pour des états avant pic, après pic avec radoucissement et pour l'état résiduel.Mots clés : sables bitumineux, structure imbriquée, bande de cisaillement, état critique.[Traduit par la Rédaction] Wong 735 Fig. 3. Computer tomography images of (a) intact specimen, and specimens with lubricated ends sheared at (b) 20 kPa and (c) 600 kPa.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Mobilized strength components of Athabasca oil sand in triaxial compression

Wong¹

1999

Can. Geotech. J.

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“…Many researchers have used experimental methods to (i) develop a constitutive model to predict the effective stress/strain behavior of drained and recompacted oil sands [8][9][10], (ii) characterize the shear strength and permanent deformation behavior [3,[11][12][13], and (iii) study the microscopic structure [1,5]. The outcome of these testing procedures predicts the macromechanical stress/strain response of the formation.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical and microstructural DEM modeling of the viscoelastic behavior of oil sands

Gbadam¹,

Frimpong²

2017

Adv Mater Sci

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Oil sand is a composite material of quartz aggregates, bitumen, water, and air void in which the bitumen exhibits a time and temperature dependent behavior under loading. The soil skeleton (quartz aggregates) comprises dense, highly incompressible, uncemented fine interlocked grains exhibiting low in-situ void ratio, and high shear strengths and dilatancy under low normal stresses. In this work, a two-dimensional discrete element method (DEM) is developed to model the viscoelastic response of an oil sand formation. A digital sample of the oil sand with varying particle shapes and sizes were built using the discrete element software PFC2D. The oil sand microstructure was captured from an electron scanning micrograph image of a 14.5% bitumen content Athabasca oil sand. The micromechanical approach is based on discretizing the oil sands microstructure and modeling particle interactions (contacts) of its constituents at microscale. The quartz aggregates, water, and bitumen included in the digital samples were modeled using different contact models. Rheological data for the bitumen was obtained from a stress/strain controlled rheometer equipped with a parallel plate. This data was used to calibrate the parameters of the viscoelastic contact models among the different material phases. The resulting parameters of Burger's model were used to simulate the micromechanical behavior of the material. A 2D DEM model with two temperatures and three loading frequencies subjected to a constant amplitude sinusoidal compression tests was simulated. The results of the study show a good agreement between the model prediction and the measured dynamic modulus and phase angle. This indicates that the linear viscoelastic DEM model developed is capable of simulating timedependent behavior of oil sands material. Additionally, the effect of rate of loading and temperature on the deformational mechanics of the material was evident in the dynamic modulus determination.

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“…Much research during the past 30 years has recognized the importance of geomechanics in SAGD and CSS, which are both broadly used in Canadian oil-sand reservoirs. Extensive experimental studies by Dusseault and Morgenstern (1978), Agar et al (1987), Scott and Seto (1986), Kosar et al (1987), Oldakowski (1994), Scott et al (1994), Chalaturnyk (1996), Samieh and Wong (1997), and Touhidi-Baghini (1998) established a very good understanding of the geomechanical behavior of oil sand under thermal and nonthermal conditions and its influence on hydraulic properties such as absolute permeability and porosity. These results opened the window for further studies in numerical modeling.…”

Section: Introductionmentioning

confidence: 99%

The Role of Geomechanical Observation in Continuous Updating of Thermal-Recovery Simulations With the Ensemble Kalman Filter

Azad

Chalaturnyk

2013

SPE Journal

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In-situ thermal methods such as steam-assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS) are widely used in oil-sand reservoirs. The physics of such thermal processes is generally well-understood, and it has been shown that rock properties are highly influenced by the geomechanical behavior of the reservoir during these recovery processes. Geomechanics improves the process dynamically, and its response can depict the progress of production within a reservoir. However, the potential of geomechanical monitoring is not usually practiced. With increased implementation of highly instrumented wells and communication technologies providing real-time monitoring data from different sources, combining available data into reservoir geomechanical simulations can improve updating numerical models and the prediction process. This research explores effective uses of geomechanical observation data for history matching and types of geomechanical observation sources adequate for thermal recovery. The ensemble Kalman filter (EnKF), combined with an iterative geomechanical coupled simulator, has been chosen as the data-assimilation algorithm to update the model continuously on the basis of geomechanical observations and production data. The results show that considering geomechanical modeling and observation improves history matching when geomechanical behavior plays a role in the process.

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Deformation of Athabasca oil sand at low effective stresses under varying boundary conditions

Cited by 38 publications

References 4 publications

Mobilized strength components of Athabasca oil sand in triaxial compression

Mobilized strength components of Athabasca oil sand in triaxial compression

Micromechanical and microstructural DEM modeling of the viscoelastic behavior of oil sands

The Role of Geomechanical Observation in Continuous Updating of Thermal-Recovery Simulations With the Ensemble Kalman Filter

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