Improved Prediction of Oil Recovery From Waterflooded Fractured Reservoirs Using Homogenization

Salimi, Hamidreza; Bruining, J.

doi:10.2118/115361-pa

Cited by 23 publications

(24 citation statements)

References 35 publications

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“…In this paper, we extend our previous work [44][45][46] on upscaling waterdrive recovery in fractured reservoirs to include non-equilibrium effects in capillary pressures and relative permeabilities. The two mostused non-equilibrium theories are due to Barenblatt and Hassanizadeh.…”

Section: Physical Modelmentioning

confidence: 92%

“…The numerical procedure described below is an extension of the method used by Arbogast [5] and Salimi and Bruining [42,44] for the sugar-cube model. The difficulty arises due to the coupling of flow in the vertical direction, which is important in the upscaled-VFR model.…”

Section: Numerical Solutionmentioning

confidence: 99%

“…Virtually, all reservoirs contain at least some natural fractures [1,32]. However, from the point of view of reservoir modeling, a fractured reservoir is defined as a reservoir in which naturally occurring fractures have a significant effect on fluid flow [42][43][44][45][46]. We only consider reservoirs where fluid flow occurs predominantly in a connected-fracture network and do not consider the case of limited connectivity and cases in which fractures act as a barrier to fluid flow.…”

Section: Introductionmentioning

confidence: 99%

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Upscaling of fractured oil reservoirs using homogenization including non-equilibrium capillary pressure and relative permeability

Salimi

Bruining

2011

Comput Geosci

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Recovery from incompletely water-wet fractured reservoirs can be extremely low. A reason for the low recovery is related to wetting issues, whereas the reason for slow recovery can be the non-equilibrium behavior of capillary pressure. One of the non-equilibrium theories is developed by Barenblatt et al. and it modifies both capillary pressure and relative permeabilities. The other theory is developed by Hassanizadeh et al. and it only deals with non-equilibrium effects for capillary pressure. To incorporate non-equilibrium in larger-scale problems, we apply homogenization to derive an upscaled model for fractured reservoirs in which the nonequilibrium effects are included. We formulate a fully implicit three-dimensional upscaled numerical model. Furthermore, we develop a computationally efficient numerical approach to solve the upscaled model. We use simulations to determine the range of delay times and capillary-damping coefficients for which discernable effects occur in terms of oil recovery. It is shown that at low Peclet numbers, i.e., when the residence time of the fluids in the fracture is long with respect to the imbibition time, incorporation of delay times of the order of few months have no significant effect on the oil recovery. However, when the Peclet number is large, the delay times reduce the rate of oil recovery. We discuss for which values of the delay time (Barenblatt) and capillary-damping coefficient (Hassanizadeh), significant delays in oil production occur.

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Section: Physical Modelmentioning

confidence: 92%

Section: Numerical Solutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Upscaling of fractured oil reservoirs using homogenization including non-equilibrium capillary pressure and relative permeability

Salimi

Bruining

2011

Comput Geosci

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“…Moreover, we compare the upscaled results for the aggregated columns with results obtained for sugar cube models described in a previous paper (Salimi and Bruining 2009), for various Peclet numbers (capillary diffusion time in matrix columns/residence time in fractures) and gravity numbers. Furthermore, we compare with results from the effective permeability model, which in principle is a conventional single-porosity model.…”

Section: Introductionmentioning

confidence: 95%

Upscaling in Vertically Fractured Oil Reservoirs Using Homogenization

Salimi

Bruining

2009

Transp Porous Med

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Flow modeling in fractured reservoirs is largely confined to the so-called sugar cube model. Here, however, we consider vertically fractured reservoirs, i.e., the situation that the reservoir geometry can be approximated by fractures enclosed columns running from the base rock to the cap rock (aggregated columns). This article deals with the application of the homogenization method to derive an upscaled equation for fractured reservoirs with aggregated columns. It turns out that vertical flow in the columns plays an important role, whereas it can be usually disregarded in the sugar cube model. The vertical flow is caused by coupling of the matrix and fracture pressure along the vertical faces of the columns. We formulate a fully implicit three-dimensional upscaled numerical model. Furthermore, we develop a computationally efficient numerical approach. As found previously for the sugar cube model, the Peclet number, i.e., the ratio between the capillary diffusion time in the matrix and the residence time of the fluids in the fracture, plays an important role. The gravity number plays a secondary role. For low Peclet numbers, the results are sensitive to gravity, but relatively insensitive to the water injection rate, lateral matrix column size, and reservoir geometry, i.e., sugar cube versus aggregated column. At a low Peclet number and sufficiently low gravity number, the effective permeability model gives good results, which agree with the solution of the aggregated column model. However, ECLIPSE simulations (Barenblatt or Warren and Root (BWR) approach) show deviations at low Peclet numbers, but show good agreement at intermediate Peclet numbers. At high Peclet numbers, the results are relatively insensitive to gravity, but sensitive to the other conditions mentioned above. The ECLIPSE simulations and the effective permeability model show large deviations from the aggregated column model at high Peclet numbers. We conclude that at low Peclet numbers, it is advantageous to increase the water injection rate to improve the net present value. However, at high Peclet numbers, increasing the flow rate may lead to uneconomical water cuts.

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“…Moreover, for heterogeneous layered fractured reservoirs, which are even more adversely affected by capillary effects, miscible flooding adds the advantage of interfacial tension elimination and thus enhancing the drainage rate and microscopic sweep efficiency. On the other hand, due to the existence of highly conductive and interconnected fracture networks, viscous forces are usually negligible compared to gravity forces (Salimi and Bruining 2010). Consequently, gravity (convection) drive and diffusion/dispersion drive are considered to be the dominant mechanisms responsible for the miscible recovery from fractured reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Interactions between Matrix and Fracture in Miscible Solvent Flooding of Fractured Reservoirs

Amerighasrodashti¹,

Farajzadeh²,

Verlaan³

et al. 2013

Proceedings

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SUMMARYMiscible solvent injection has received increasing attention in recent years as an efficient method to improve oil recovery from fractured reservoirs. Due to the large permeability difference between fracture and matrix, the success of this method depends to large extent on the degree of enhancement of the mass exchange rate between the solvent flowing through the fracture and the oil residing in the matrix. A series of experiments have been conducted to investigate the mass transfer rate between the fracture and the matrix. Different scenarios have been considered to examine the effect of flow rate, matrix permeability, fracture aperture, and oil properties. To this end a porous medium (fully saturated with oil) is placed in a vertical core holder that can be used in a CT scanner, to simulate the matrix. A small slit between the porous medium and the core holder simulates the fracture. The interaction between the matrix and fracture is visualized for solvent flooding by means of CT-Scanning, which can be used to validate theories of enhanced transfer in fractured media. The experimental data are compared with a simulation model that takes diffusive, gravitational and convective forces into account.

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Improved Prediction of Oil Recovery From Waterflooded Fractured Reservoirs Using Homogenization

Cited by 23 publications

References 35 publications

Upscaling of fractured oil reservoirs using homogenization including non-equilibrium capillary pressure and relative permeability

Upscaling of fractured oil reservoirs using homogenization including non-equilibrium capillary pressure and relative permeability

Upscaling in Vertically Fractured Oil Reservoirs Using Homogenization

Dynamic Interactions between Matrix and Fracture in Miscible Solvent Flooding of Fractured Reservoirs

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