Geomechanical and Thermal Reservoir Simulation Demonstrates SAGD Enhancement Due to Shear Dilation

Collins, P.M.; Carlson, M.R.; Walters, D.A.; Settari, A.

doi:10.2523/78237-ms

Cited by 9 publications

(11 citation statements)

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“…1 (modified from Yuan et al 2011a). The fracturing results in a continuous dilated zone embedded with many unconnected microcracks instead of linear apertures (Chhina and Agar 1985;Kry et al 1992;Collins et al 2002;Yuan et al 2011a). In this regard, the term ''hydraulic fracturing'' is more appropriately described as ''water injection'' for the case concerned.…”

Section: Introductionmentioning

confidence: 95%

“…This dilation-oriented water injection has obtained success in the stimulation of the Alberta oil sand (Collins et al 2002;Collins 2005). The marine-facies Alberta oil sand reservoirs experienced preconsolidation by historical loading of a 2-3 km thick glacial ice sheet during the Quaternary period, which was equal to 20-30 MPa overburden pressure, and a subsequent transformation of tangential to interpenetrative grain contact (Clark 1980, Oldakowski 1994Yuan et al 2011a), leading to its high shear strength and distinct dilative behavior at low confining pressures (Barnes 1980;Barnes and Dusseault 1981).…”

Section: Introductionmentioning

confidence: 96%

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Experimental Investigation on Dilation Mechanisms of Land-Facies Karamay Oil Sand Reservoirs under Water Injection

et al. 2015

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The success of steam-assisted gravity drainage (SAGD) is strongly dependent on the formation of a homogeneous and highly permeable zone in the land-facies Karamay oil sand reservoirs. To accomplish this, hydraulic fracturing is applied through controlled water injection to a pair of horizontal wells to create a dilation zone between the dual wells. The mechanical response of the reservoirs during this injection process, however, has remained unclear for the land-facies oil sand that has a loosely packed structure. This research conducted triaxial, permeability and scanning electron microscopy (SEM) tests on the field-collected oil sand samples. The tests evaluated the influences of the field temperature, confining stress and injection pressure on the dilation mechanisms as shear dilation and tensile parting during injection. To account for petrophysical heterogeneity, five reservoir rocks including regular oil sand, mud-rich oil sand, bitumen-rich oil sand, mudstone and sandstone were investigated. It was found that the permeability evolution in the oil sand samples subjected to shear dilation closely followed the porosity and microcrack evolutions in the shear bands. In contrast, the mudstone and sandstone samples developed distinct shear planes, which formed preferred permeation paths. Tensile parting expanded the pore space and increased the permeability of all the samples in various degrees. Based on this analysis, it is concluded that the range of injection propagation in the pay zone determines the overall quality of hydraulic fracturing, while the injection pressure must be carefully controlled. A region in a reservoir has little dilation upon injection if it remains unsaturated. Moreover, a cooling of the injected water can strengthen the dilation potential of a reservoir. Finally, it is suggested that the numerical modeling of water injection in the Karamay oil sand reservoirs must take into account the volumetric plastic strain in hydrostatic loading.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 96%

Experimental Investigation on Dilation Mechanisms of Land-Facies Karamay Oil Sand Reservoirs under Water Injection

et al. 2015

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“…In Equation 11, it is assumed that the pressure is conducted through the cold oil sands by the effective mobility of the water phase. It must be noted that by reducing the effective stresses, the strength and stiffness of the oil sand formation is reduced (Collins et al, 2002b). In this study the reduction in stiffness of oil sand as a result of reduction in effective stresses is neglected.…”

Section:   mentioning

confidence: 95%

Modifications to Butler Theory for Geomechanical Effects at the Edge of SAGD Steam Chamber. Part I: Drained Condition

Irani¹,

Gates

2013

All Days

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Steam-assisted gravity drainage (SAGD) has been demonstrated to be a successful thermal recovery technique for recovering bitumen from oil sand reservoirs where the viscosity of the bitumen is typically hundreds of thousands to millions of centipoise. High pressure and high temperature steam injection cause significant stress changes at the edge of the steam chamber including shear dilation which, in turn, can enhance the absolute permeability. The importance of considering geomechanical effects in SAGD process has been extensively discussed in the literature but geomechanical effects have been neglected in the classic SAGD analytical models. All analytical models are typically incapable of fully predicting actuall SAGD production rates without using a correction factor; this can be a result of neglecting geomechanical effects. In the research documented here, we examine geomechanical enhancement at the edge of steam chamber where the oil sand has been sheared under thermal stimulation. We describe a mechanism and evaluate the oil drainage parallel to the interface of steam chamber caused by permeability enhancement from thermal stresses. Finally, we present a modified Butler's Theory that includes geomechanical effects. The results are directly applicable to understanding the geomechanical effects on oil drainage flow at the edge of SAGD chamber.

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“…Literature has documented numerous geomechanical studies for the SAGD process (Agar, 1984;Vaziri, 1989 and1990;Settari, 1989 and1992;Settari et al 1992;Fung et al 1994;Chalaturnyk, 1996;Ito and Suzuki, 1996;Touhidi-Baghini, 1998;Collins et al, 2002;Li et al 2004;Du and Wong, 2007;Yin et al 2009;Huang et al 2010). Agar (1984) conducted a geotechnical testing of undisturbed Alberta oil sands at elevated temperature and pressures in his PhD thesis.…”

Section: Geomechanical Modeling In Sagd Processmentioning

confidence: 97%

Numerical Simulation of ES-SAGD Process in Athabasca Oil Sands with Top Water and Gas Thief Zones

et al. 2011

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Overlying top water and gas thief zones have a detrimental effect on the Steam-Assisted Gravity Drainage (SAGD) recovery process since steam penetrates into these zones which results in great heat loss. Due to the presence of these top thief zones, recovering bitumen by the SAGD process has become challenging for the Athabasca oil sands.Numerical simulations, laboratory experiments and field production data have demonstrated that oil production tends to decrease as the depletion of top gas occurs; also, heat loss to the overlying thief zone will be more significant when a top water zone is present. Indeed, SAGD is a coupled geomechanical, thermal and fluid flow problem because continuous steam injection changes reservoir pore pressure and temperature, which can alter the effective stress in-situ. Therefore, to represent the physics of thermal flow and soil geomechanics, a coupled geomechanical simulation that solves the flow and stress equation simultaneously in the reservoir is crucial for modeling the SAGD process.The objective of this paper is to construct a 3D geostatistical model for the Surmont pilot and implement coupled geomechanical modeling for the SAGD process aiming at investigating the impact of dilation and thermal expansion on the surface subsidence and bitumen recovery. Reasonable history match of oil and water rates has been achieved and steam chamber profiles have been conformed to the field data from the observation wells. An Expanding Solvent Steam-Assisted Gravity Drainage (ES-SAGD) process has been investigated on a full field-based heterogeneous simulation model using an optimal solvent mixture. Finally, geomechanical effects on the ES-SAGD process are investigated through an iterative coupling approach. IntroductionThe negative impacts of top water and gas cap on SAGD performance have been previously presented and discussed in the literature (Good et al. 1997;Nasr et al. 2000;Law et al. 2000). Both experimental and simulation approaches were conducted to determine SAGD steam chamber growth in the presence of a top thief zone. It was observed that the overlying top water and gas thief zones have a detrimental effect on the Steam Assisted Gravity Drainage (SAGD) recovery process since steam penetrates into these zones and results in great heat loss (AEUB, 1998). Thermal SAGD simulations models have been constructed and successfully matched using the computer assisted history-matching approach. The optimization strategies have been proposed in terms of the operating pressure and subcool control. Furthermore, ES-SAGD possibilities have been investigated using different solvent mixture co-injected with steam. Through a sensitivity study, an optimal solvent mixture has been proposed for this case with a top thief zone.SAGD is a coupled geomechanical, thermal and fluid flow problem because continuous steam injection changes reservoir pore pressure and temperature, which can alter the effective stress in-situ. Dilation behavior associated with volumetric strains is triggered by the continuous stea...

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Geomechanical and Thermal Reservoir Simulation Demonstrates SAGD Enhancement Due to Shear Dilation

Cited by 9 publications

References 1 publication

Experimental Investigation on Dilation Mechanisms of Land-Facies Karamay Oil Sand Reservoirs under Water Injection

Experimental Investigation on Dilation Mechanisms of Land-Facies Karamay Oil Sand Reservoirs under Water Injection

Modifications to Butler Theory for Geomechanical Effects at the Edge of SAGD Steam Chamber. Part I: Drained Condition

Numerical Simulation of ES-SAGD Process in Athabasca Oil Sands with Top Water and Gas Thief Zones

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