Discrete fracture networks modeling of shale gas production and revisit rate transient analysis in heterogeneous fractured reservoirs

Wang, Hanyi

doi:10.1016/j.petrol.2018.05.029

Cited by 38 publications

(11 citation statements)

References 49 publications

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“…In addition, DFITs in most low permeability formations demonstrate extremely long after-closure linear flow behavior, which can only happen without the pressure interference of adjacent fractures. So, unless the "networks of pre-existing natural fractures" already exist in the first place, such as in coalbed methane (CBM) or some heavily fractured carbonate reservoirs, that exhibit highly stress-sensitive permeability in DFIT analysis (Wang and Sharma 2019a;2019b) or rate transient analysis (Wang 2018), it seems that the "fracture network" may occur much less common than we expected in unconventional reservoirs.…”

Section: Fig18 the Analogy Between Multi-fracturing Within A Certaimentioning

confidence: 87%

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Wang

2019

Journal of Natural Gas Science and Engineering

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All reservoirs are fractured to some degree. Depending on the density, dimension, orientation and the cementation of natural fractures and the location where the hydraulic fracturing is done, pre-existing natural fractures can impact hydraulic fracture propagation and the associated flow capacity. Understanding the interactions between hydraulic fracture and natural fractures is crucial in estimating fracture complexity, stimulated reservoir volume (SRV), drained reservoir volume (DRV) and completion efficiency. However, what hydraulic fracture looks like in the subsurface, especially in unconventional reservoirs, remain elusive, and many times, field observations contradict our common beliefs. In this study, a global cohesive zone model is presented to investigate hydraulic propagation in naturally fractured reservoirs, along with a comprehensive discussion on hydraulic fracture propagation behaviors in naturally fractured reservoirs. The results indicate that in naturally fractured reservoirs, hydraulic fracture can turn, kink, branch and coalesce, and the fracture propagation path is quite complex, but it does not necessarily mean that fracture networks can be created, even under low horizontal stress difference, because of strong stress shadow effect and flow-resistance dependent fluid distribution. Perhaps, 'complex fracture', rather than 'fracture networks', is the norm in most unconventional reservoirs.

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Section: Fig18 the Analogy Between Multi-fracturing Within A Certaimentioning

confidence: 87%

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Wang

2019

Journal of Natural Gas Science and Engineering

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135

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“…In propped fractures, the stress distribution after closure can substantially influence the crushing or embedment of proppants and the resulting conductivity (Warpinski 2010). Those stress dependent fracture conductivity not only impact hydrocarbon production, but also disturb our rate transient analysis (RTA) of production data (Wang 2017b). In addition, the changes of fracture stiffness/compliance during closure can have a significant impact on the determination of in-situ stress using diagnostic fracture injection tests (DFITs) or flow back tests.…”

Section: Fig1 Example Of Fracture Surface Roughness Pattern (Van Dammentioning

confidence: 99%

A non-local model for fracture closure on rough fracture faces and asperities

Wang

Sharma

2017

Journal of Petroleum Science and Engineering

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Natural fractures, hydraulic fractures, and acid etched fractures have some degree of fracture surface roughness. These surface asperities are largely responsible for the hydraulic conductivity of these fractures. This paper presents a model to quantify the fracture closure process that is crucial to predicting the stress dependent conductivity of fracture networks in unconventional reservoirs and estimating the minimum in-situ stress using fracture injection tests. Past studies that have investigated the fracture closure process have assumed the fracture surfaces to be two parallel plates closing in uniformly on rough surfaces and asperities. In reality hydraulically induced fractures are wider in the middle and narrower near the fracture tip. As a result, asperities on the rough fracture surfaces come into contact near the fracture tip well before they do near the middle of the fracture. The evolution of the entire fracture geometry and its impact on stress redistribution and dynamic fracture closure behavior has not yet been investigated.In this paper, we present a method and general algorithms to model the dynamic closure behavior of a hydraulic fracture while accounting for the initial fracture shape, rough fracture surfaces and deformation of asperities in contact. Analytic solutions from linear elastic fracture mechanics for three fracture models (PKN, KGD and radial fracture geometry) are coupled with a general contact law to show that the fracture closure process is a gradual, non-local process, which occurs at the fracture edges initially and then moves progressively to the center of fracture, as the fluid pressure inside the fracture declines. Our study also reveals that the minimum in-situ stress should not be picked at the occurrence of mechanical closure as conventional practice suggests.

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“…Modeling groundwater flow and solute transport in fractured rocks is essential in engineering, geology, and hydrogeology studies. Many applications, including gas/oil transport within the fractured system in the shale formation, artificial fractures by hydraulic fracturing methods for increasing the connectivity of a fracture system, and enhanced geothermal system (EGS) in hot and dry formations, have been widely investigated based on the knowledge of flow and transport in the fractured rocks [1][2][3][4]. In the procedures of site characterization investigation for the spent nuclear fuel final disposal, the solute transport in the fractured systems plays an essential role because the critical issue has been focused on the release of radionuclides from the deposition holes (DHs) in the disposal facility to the human environment, i.e., the biosphere [5,6].…”

Section: Introductionmentioning

confidence: 99%

Numerical Assessment of the Hybrid Approach for Simulating Three-Dimensional Flow and Advective Transport in Fractured Rocks

Lee

et al. 2021

Applied Sciences

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This study presents a hybrid approach for simulating flow and advective transport dynamics in fractured rocks. The developed hybrid domain (HD) model uses the two-dimensional (2D) triangular mesh for fractures and tetrahedral mesh for the three-dimensional (3D) rock matrix in a simulation domain and allows the system of equations to be solved simultaneously. This study also illustrates the HD model with two numerical cases that focus on the flow and advective transport between the fractures and rock matrix. The quantitative assessments are conducted by comparing the HD results with those obtained from the discrete fracture network (DFN) and equivalent continuum porous medium (ECPM) models. Results show that the HD model reproduces the head solutions obtained from the ECPM model in the simulation domain and heads from the DFN model in the fractures in the first case. The particle tracking results show that the mean particle velocity in the HD model can be 7.62 times higher than that obtained from the ECPM mode. In addition, the developed HD model enables detailed calculations of the fluxes at intersections between fractures and cylinder objects in the case and obtains relatively accurate flux along the intersections. The solutions are the key factors to evaluate the sources of contaminant released from the disposal facility.

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Discrete fracture networks modeling of shale gas production and revisit rate transient analysis in heterogeneous fractured reservoirs

Cited by 38 publications

References 49 publications

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

A non-local model for fracture closure on rough fracture faces and asperities

Numerical Assessment of the Hybrid Approach for Simulating Three-Dimensional Flow and Advective Transport in Fractured Rocks

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