A Fractal Permeability Model Coupling Boundary-Layer Effect for Tight Oil Reservoirs

Wang, Fuyong; Liu, Zhichao; Liang, Jenn‐Tai; Wang, Congle; Guo, Hu

doi:10.1142/s0218348x17500426

Cited by 30 publications

(11 citation statements)

References 31 publications

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“…Limited efforts have been made in the literature to investigate the dynamic capillary pressure in a hydraulic fractured porous media, especially the experimental studies. Moreover, it is observed that tight rocks are associated with large boundary layer effect on fluid flow, and such phenomenon is also required to be considered when integrating the dynamic effect in these rocks.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the dynamic capillary pressure during displacement process in fractured tight rocks

Chen

et al. 2019

AIChE Journal

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This work investigates the dynamic capillary pressure during the displacement process in fractured tight rocks, through specially designed experiments on fractured and intact core samples. The dynamic capillarity coefficient of matrix and the multiphase flow behaviors are also obtained. Results have shown that the dynamic capillary pressure of the matrix becomes around 5-20% higher after the fracturing treatment. The lower and less variable values of dynamic capillarity coefficient of matrix illustrate a weakened dynamic effect and a more uniform displacement front. Moreover, time derivative of water saturation is increased significantly with fractures. Finally, oil relative permeability after fracturing is lower than its value of the intact core at high water saturations. A dynamic capillarity coefficient model for matrix, which includes the influence of fractures, is derived and verified with the average R 2 more than 0.95. This wok helps to understand and predict multiphase flow in fractured tight porous media.

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Section: Introductionmentioning

confidence: 99%

Investigation of the dynamic capillary pressure during displacement process in fractured tight rocks

Chen

et al. 2019

AIChE Journal

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“…Fractal dimension is the main tool to characterize the complex structure of the fractal object, and the introduction of which is the novelty of fractal theory. It can be easily noticed from existing fractal research that the relationship between the fractal dimensions of the research objects and other physical parameters is the focus of many studies [43,44].…”

Section: The Box-counting Methods and Fractal Dimensionmentioning

confidence: 99%

Flow Simulation of Artificially Induced Microfractures Using Digital Rock and Lattice Boltzmann Methods

Yang

Liu

et al. 2018

Energies

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Abstract:Microfractures have great significance in the study of reservoir development because they are an effective reserving space and main contributor to permeability in a large amount of reservoirs. Usually, microfractures are divided into natural microfractures and induced microfractures. Artificially induced rough microfractures are our research objects, the existence of which will affect the fluid-flow system (expand the production radius of production wells), and act as a flow path for the leakage of fluids injected to the wells, and even facilitate depletion in tight reservoirs. Therefore, the characteristic of the flow in artificially induced fractures is of great significance. The Lattice Boltzmann Method (LBM) was used to calculate the equivalent permeability of artificially induced three-dimensional (3D) fractures. The 3D box fractal dimensions and porosity of artificially induced fractures in Berea sandstone were calculated based on the fractal theory and image-segmentation method, respectively. The geometrical parameters (surface roughness, minimum fracture aperture, and mean fracture aperture), were also calculated on the base of digital cores of fractures. According to the results, the permeability lies between 0.071-3.759 (dimensionless LB units) in artificially induced fractures. The wide range of permeability indicates that artificially induced fractures have complex structures and connectivity. It was also found that 3D fractal dimensions of artificially induced fractures in Berea sandstone are between 2.247 and 2.367, which shows that the artificially induced fractures have the characteristics of self-similarity. Finally, the following relations were studied: (a) exponentially increasing permeability with increasing 3D box fractal dimension, (b) linearly increasing permeability with increasing square of mean fracture aperture, (c) indistinct relationship between permeability and surface roughness, and (d) linearly increasing 3D box fractal dimension with increasing porosity.

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“…The geometry of a fracture network is related to the fractal controlling parameters, and the multi-level bifurcated geometry of a fractal fracture better represents fractures of different orders and branches. Fuyong et al [21,22] investigate fluid flow in fractal porous media and propose simulation method for the permeability of porous media based on the multiple fractal models.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Fluid Flow through Fractal-Based Discrete Fractured Network

Wang

et al. 2018

Energies

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Abstract:In recent years, multi-stage hydraulic fracturing technologies have greatly facilitated the development of unconventional oil and gas resources. However, a quantitative description of the "complexity" of the fracture network created by the hydraulic fracturing is confronted with many unsolved challenges. Given the multiple scales and heterogeneity of the fracture system, this study proposes a "bifurcated fractal" model to quantitatively describe the distribution of induced hydraulic fracture networks. The construction theory is employed to generate hierarchical fracture patterns as a scaled numerical model. With the implementation of discrete fractal-fracture network modeling (DFFN), fluid flow characteristics in bifurcated fractal fracture networks are characterized. The effects of bifurcated fracture length, bifurcated tendency, and number of bifurcation stages are examined. A field example of the fractured horizontal well is introduced to calibrate the accuracy of the flow model. The proposed model can provide a more realistic representation of complex fracture networks around a fractured horizontal well, and offer the way to quantify the "complexity" of the fracture network in shale reservoirs. The simulation results indicate that the geometry of the bifurcated fractal fracture network model has a significant impact on production performance in the tight reservoir, and enhancing connectivity of each bifurcate fracture is the key to improve the stimulation performance. In practice, this work provides a novel and efficient workflow for complex fracture characterization and production prediction in naturally-fractured reservoirs of multi-stage fractured horizontal wells.

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A Fractal Permeability Model Coupling Boundary-Layer Effect for Tight Oil Reservoirs

Cited by 30 publications

References 31 publications

Investigation of the dynamic capillary pressure during displacement process in fractured tight rocks

Investigation of the dynamic capillary pressure during displacement process in fractured tight rocks

Flow Simulation of Artificially Induced Microfractures Using Digital Rock and Lattice Boltzmann Methods

Numerical Simulation of Fluid Flow through Fractal-Based Discrete Fractured Network

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