Transient Pressure Well Test Analysis Based on Compressible Discrete Fracture Network

Shchipanov, Anton; Rusakov, S. V.

doi:10.3997/2214-4609.20146426

Cited by 6 publications

(10 citation statements)

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“…Bai et al (1999) are among the first who considered the effect of fracture deformation on permeability in flow simulations but they neglected the non-linearity of fracture deformation. Later, Pao and Lewis (2002), Shchipanov and Nazarov (2005), Zhao andChen (2006), Shchipanov andRusakov (2008), Khalili (2008), Bagheri and Settari (2008), Tao et al (2009), and Ranjbar et al (2011) incorporated fracture geomechanics into modeling of naturally fractured reservoirs. For example, Bagheri and Settari (2008) included the effect of fractured-media deformation into a dual porosity approach by incorporating dynamic tensor permeability for fractures.…”

Section: Introductionmentioning

confidence: 99%

Development of an Efficient Embedded Discrete Fracture Model for 3D Compositional Reservoir Simulation in Fractured Reservoirs

et al. 2013

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Summary Many naturally fractured reservoirs around the world have depleted significantly, and improved-oil-recovery (IOR) processes are necessary for further development. Hence, the modeling of fractured reservoirs has received increased attention recently. Accurate modeling and simulation of naturally fractured reservoirs (NFRs) is still challenging because of permeability anisotropies and contrasts. Nonphysical abstractions inherent in conventional dual-porosity and dual-permeability models make them inadequate for solving different fluid-flow problems in fractured reservoirs. Also, recent technologies for discrete fracture modeling may suffer from large simulation run times, and the industry has not used such approaches widely, even though they give more-accurate representations of fractured reservoirs than dual-continuum models. We developed an embedded discrete fracture model (DFM) for an in-house compositional reservoir simulator that borrows the dual-medium concept from conventional dual-continuum models and also incorporates the effect of each fracture explicitly. The model is compatible with existing finite-difference reservoir simulators. In contrast to dual-continuum models, fractures have arbitrary orientations and can be oblique or vertical, honoring the complexity of a typical NFR. The accuracy of the embedded DFM is confirmed by comparing the results with the fine-grid, explicit-fracture simulations for a case study including orthogonal fractures and a case with a nonaligned fracture. We also perform a grid-sensitivity study to show the convergence of the method as the grid is refined. Our simulations indicate that to achieve accurate results, the embedded discrete fracture model may only require moderate mesh refinement around the fractures and hence offers a computationally efficient approach. Furthermore, examples of waterflooding, gas injection, and primary depletion are presented to demonstrate the performance and applicability of the developed method for simulating fluid flow in NFRs.

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Section: Introductionmentioning

confidence: 99%

Development of an Efficient Embedded Discrete Fracture Model for 3D Compositional Reservoir Simulation in Fractured Reservoirs

et al. 2013

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“…Dynamic permeability variation affects behaviour of a pressure transient response and its derivative, which is clearily observed in comparison of sequential pressure drawdown and build-up (Shchipanov and Rusakov, 2008). The pressure transient analysis may also be used at the second stage to estimate dynamic fracture permeability and porosity.…”

Section: A New Approach To Deformable Fractured Reservoirmentioning

confidence: 99%

“…Flow simulation is usually carried out on a well test scale with conventional reservoir simulation software or specific tools focused on flow in discrete fracture network (e.g. Shchipanov and Rusakov, 2008).…”

Section: A New Approach To Deformable Fractured Reservoirmentioning

confidence: 99%

“…Pressure transient analysis was recently extended with new interpretation methods (Shchipanov and Rusakov, 2008), which account for the dynamic fracture properties. In this paper, a more general approach to describe dynamic fracture behaviour and a new workflow to characterize deformable fractured reservoirs are proposed and applied to improve description of the Ekofisk fracture network in reservoir simulation.…”

Section: Introductionmentioning

confidence: 99%

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A New Approach to Deformable Fractured Reservoir Characterization: Case Study of the Ekofisk Field

Shchipanov

Kollbotn

Surguchev

et al. 2010

Proceedings of SPE EUROPEC/EAGE Annual Conference and Exhibition

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Production from a fractured reservoir is generally governed by the fracture network conductivity, which may be altered by changes in reservoir pressure. A new approach to naturally fractured reservoir description accounts for the variation in the fracture properties caused by the effective stress change. The basis of the proposed approach is a compressible discrete fracture network (CDFN) model with stress dependent fracture aperture and hence porosity and permeability. The new approach allowed us to develop a workflow to evaluate the stress dependent fracture properties. This workflow includes inverse and direct problem solutions. The inverse problem consists of interpretation of pressure transient well tests and production history integrating geomechanical effects. The results of core analyses, production logging and wellbore imaging provide important information for the CDFN characterization. The direct problem consists of numerical flow simulation focused on calibration of the obtained fracture properties to match well test data. Using the workflow, one can determine stress or pressure dependent fracture parameters to be used in single and dual porosity reservoir simulations.Using available field data, the proposed approach allowed us to improve characterization of the Ekofisk fracture network. The seafloor subsidence and chalk compaction observed at Ekofisk have initiated extensive studies of the reservoir geomechanics. The geomechanical effects were integrated in the reservoir characterization using the developed workflow. A decrease in well productivity and fracture conductivity due to pressure decline was obtained from the pressure transient and production analyses. This allowed us to describe the dynamic behavior of the fracture permeability and porosity. These fracture properties were then used in reservoir simulation. The simulation results have given evidence that dynamic reservoir behavior has an effect on multiphase flow comparable to well placement and relative permeability effects.

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“…Bai et al (1999) are among the first who considered the effect of fracture deformation on permeability in flow simulations but they neglected the non-linearity of fracture deformation. Later, Pao and Lewis (2002), Shchipanov and Nazarov (2005), Zhao and Chen (2006), Shchipanov and Rusakov (2008), Khalili (2008), Bagheri and Settari (2008), and Tao et al (2009) incorporated fracture geomechanics into modeling of naturally fractured reservoirs. For example, Bagheri and Settari (2008) included the effect of fractured-media deformation into a dual porosity approach by incorporating dynamic tensor permeability for fractures.…”

Section: Introductionmentioning

confidence: 99%

Coupled Geomechanics and Flow Simulation for an Embedded Discrete Fracture Model

et al. 2013

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The effect of geomechanics on fluid flow is more crucial in fractured reservoirs due to presence of fissures, which might be more stress-sensitive than the rock matrix. The flow characteristics of fractures are significantly affected by effective normal stress exerting on them. In spite of extensive experimental and field studies that have demonstrated the dynamic behavior of fractures, fracture properties have been often treated as static parameters in the simulations of naturally fractured reservoirs. Realistic modeling of production in fractured systems requires including the dynamic behavior of fractures into a discrete fracture model.We have incorporated the dynamic behavior of fractures into an embedded discrete fracture model, called EDFM. The coupled model allows inclusion of the impact of stress regime on fluid flow in a 3D discrete fracture network. We use empirical joint models to represent normal deformation of pre-existing natural fractures and couple them with the EDFM approach. Using these models, the aperture and permeability of an arbitrary-oriented fracture become functions of the effective normal stress acting on the fracture plane. In addition, we allow for fracture-conductivity tables to model dynamic behavior of propped hydraulic fractures in stimulated reservoirs.We present several examples in this study to show the applicability and performance of the coupled geomechanics-EDFM approach for the simulation of naturally fractured reservoirs. We examine the effect of pressure-dependent fracture properties on production leading to the conclusion that fracture deformation, caused by effective stress changes, substantially affects hydrocarbon recovery. Our simulations show that the significance of such effects on production strongly depends on parameters controlling the deformation behavior of fractures. Simulations also show that creating sufficiently highconductivity fractures during stimulation treatment of unconventional reservoirs can mitigate the adverse effect of hydraulic fracture closure on production to a good extent. Furthermore, the coupled geomechanics-EDFM approach does not degrade the computational performance of EDFM, which is a promising new approach for modeling discrete fractures in a robust and efficient manner.

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Transient Pressure Well Test Analysis Based on Compressible Discrete Fracture Network

Cited by 6 publications

References 0 publications

Development of an Efficient Embedded Discrete Fracture Model for 3D Compositional Reservoir Simulation in Fractured Reservoirs

Development of an Efficient Embedded Discrete Fracture Model for 3D Compositional Reservoir Simulation in Fractured Reservoirs

A New Approach to Deformable Fractured Reservoir Characterization: Case Study of the Ekofisk Field

Coupled Geomechanics and Flow Simulation for an Embedded Discrete Fracture Model

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