Investigation of immiscible CO2and C1injection and comparison with water injection for enhanced oil recovery in naturally fractured reservoirs

The fractured low permeability reservoirs develop complex fracture network. As the of waterflooding recovery heightens, excessive high injection pressures and excessive water injection rate will result in open, initiation, propagation and coalescence of micro-fracture, connecting injection with production form the high permeability zone, which results in a one-way onrush of waterflooding, water cut in oil well water rise quickly, causing a severe oil well flooding and channeling, thereby reducing the ultimate oil recovery efficiency. The effect of the waterflooding seepage within natural fracture on fracture initiation is studied and analyzed here, applying the theory of rock fracture mechanics to analyze the interaction of fracture system for naturally fractured reservoirs in waterflooding developing process, studying the mechanical mechanism of opening, initiation, propagation and coalescence of natural fracture under injection pressure, which is important theoretical significance for studying the distribution law of fracture and defining appreciate water injection mode and injection pressure in the process of injection development of the naturally fractured reservoir and for delaying the directivity water break-through and water flooding rate of oil well in the process of injection development.

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Oil Recovery and Sequestration Potential of Naturally Fractured Reservoirs During CO2Injection

Energy & Fuels ◽

10.1021/ef900361n ◽

2009 ◽

Vol 23 (8) ◽

pp. 4025-4036 ◽

Cited By ~ 27

Author(s):

J. J. Trivedi ◽

T. Babadagli

Keyword(s):

Oil Recovery ◽

Fractured Reservoirs ◽

Naturally Fractured Reservoirs ◽

Sequestration Potential ◽

Naturally Fractured

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

SPE Journal ◽

10.2118/154246-pa ◽

2013 ◽

Vol 19 (02) ◽

pp. 289-303 ◽

Cited By ~ 172

Author(s):

Ali Moinfar ◽

Abdoljalil Varavei ◽

Kamy Sepehrnoori ◽

Russell T. Johns

Keyword(s):

Fluid Flow ◽

Oil Recovery ◽

Fractured Reservoirs ◽

Naturally Fractured Reservoirs ◽

Fracture Model ◽

Continuum Models ◽

Fine Grid ◽

Discrete Fracture Model ◽

Discrete Fracture ◽

Naturally Fractured

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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