A fully coupled multiscale shale deformation-gas transport model for the evaluation of shale gas extraction

Cao, Peng; Liu, Jishan; Leong, Yee-Kwong

doi:10.1016/j.fuel.2016.03.055

Cited by 130 publications

(94 citation statements)

References 34 publications

(49 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nine fractured fractures with infinite conductivity are symmetrical about horizontal wells. For reservoir simulations with the 2D geometry, the hydraulic fractures are treated as one‐dimensional line by representing the fractures as the interior boundaries of matrix . The geometric model of reservoir and the main parameter used in calculation are shown in Figure and Table , respectively.…”

Section: Model Solution and Results Analysismentioning

confidence: 99%

Numerical simulation of a coupled gas flow and geomechanics process in fractured coalbed methane reservoirs

Zhang

Chen³

et al. 2019

Energy Science & Engineering

View full text Add to dashboard Cite

The pores and throats of coal seam are narrow, and the permeability is very low. It is a porous medium with complicated deformation mechanism. In the process of gas production, the change of stress, pore pressure, gas adsorption and desorption will lead to the change of grains, pore volume, and the seepage capacity of coal seam. Based on the theory of poroelastic and seepage mechanics, a physical model of fractured horizontal well and a coupled mathematic model of coal deformation and gas flow are established. The dynamic change model of permeability is deduced too. The development characteristics and laws of coalbed methane are numerically simulated by using numerical analysis software Comsol Multiphysics. Finally, the sensitivity of the key parameters in the model and the influence of the fracture parameters are analyzed. The results show that the application of fractured horizontal well is an effective measure to increase production of coalbed reservoirs; with the increase of Langmuir volumetric strain constant, fracture half‐length, and the numbers of fracture, the production of coalbed methane is increasing. In the case of constant total fracture length, number, and spacing, when fracture half‐lengths are long and short interlaced distribution, the production is the highest and it is the best fracture distribution pattern. The study provides a theoretical basis for the further study of coalbed deformation, gas migration, efficient, and rational development of coalbed methane reservoirs.

show abstract

Section: Model Solution and Results Analysismentioning

confidence: 99%

Numerical simulation of a coupled gas flow and geomechanics process in fractured coalbed methane reservoirs

Zhang

Chen³

et al. 2019

Energy Science & Engineering

View full text Add to dashboard Cite

show abstract

“…A history matching with field production data on a Barnett shale has performed. The field production and simulation data are adopted from literature (Cao, Liu and Leong, 2016;Yu and Kamy Sepehrnoori, 2014). The detailed reservoir and fluid parameters are shown as in Fig.…”

Section: Case 3: History Matching and Production Forecastmentioning

confidence: 99%

“…Also, the effect of these mechanism on practical well performance is not clear. To the best of our knowledge, almost all existing numerical models for shale gas reservoir are implemented in in-house simulators or commercial simulators (Jiang and Younis, 2015, Cao et al, 2016, Wang et al, 2017and Akkutlu et al, 2018. Hence, it is necessary to develop a flexible and generic open-source framework to fill this gap.…”

Section: Introductionmentioning

confidence: 99%

MRST-Shale: An Open-Source Framework for Generic Numerical Modeling of Unconventional Shale and Tight Gas Reservoirs

Wang¹

2020

Preprint

View full text Add to dashboard Cite

We present a generic and open-source framework for the numerical modeling of the expected transport and storage mechanisms in unconventional gas reservoirs. These unconventional reservoirs typically contain natural fractures at multiple scales. Considering the importance of these fractures in shale gas production, we perform a rigorous study on the accuracy of different fracture models. The framework is validated against an industrial simulator and is used to perform a history-matching study on the Barnett shale. This work presents an open-source code that leverages cutting-edge numerical modeling capabilities like automatic differentiation, stochastic fracture modeling, multi-continuum modeling and other explicit and discrete fracture models. We modified the conventional mass balance equation to account for the physical mechanisms that are unique to organic-rich source rocks. Some of these include the use of an adsorption isotherm, a dynamic permeability-correction function, and an embedded discrete fracture model (EDFM) with fracture-well connectivity. We explore the accuracy of the EDFM for modeling hydraulically-fractured shale-gas wells, which could be connected to natural fractures of finite or infinite conductivity, and could deform during production. Simulation results indicates that although the EDFM provides a computationally efficient model for describing flow in natural and hydraulic fractures, it could be inaccurate under these three conditions: 1. when the fracture conductivity is very low. 2. when the fractures are not orthogonal to the underlying Cartesian grid blocks, and 3. when sharp pressure drops occur in large grid blocks with insufficient mesh refinement. Each of these results are very significant considering that most of the fluids in these ultra-low matrix permeability reservoirs get produced through the interconnected natural fractures, which are expected to have very low fracture conductivities. We also expect sharp pressure drops near the fractures in these shale gas reservoirs, and it is very unrealistic to expect the hydraulic fractures or complex fracture networks to be orthogonal to any structured grid. In conclusion, this paper presents an open-source numerical framework to facilitate the modeling of the expected physical mechanisms in shale-gas reservoirs. The code was validated against published results and a commercial simulator. We also performed a history-matching study on a naturally-fractured Barnett shale-gas well considering adsorption, gas slippage & diffusion and fracture closure as well as proppant embedment, using the framework presented. This work provides the first open-source code that can be used to facilitate the modeling and optimization of fractured shale-gas reservoirs. To provide the numerical flexibility to accurately model stochastic natural fractures that are connected to hydraulically-fractured wells, it is built atop other related open-source codes. We also present the first rigorous study on the accuracy of using EDFM to model both hydraulic fractures and natural fractures that may or may not be interconnected.

show abstract

“…For most low permeability reservoirs, hydraulic fracturing and horizontal drilling are the key techniques to extract natural gas. Gas production in shale reservoirs is attributed to the conductivity of the matrix and fracture systems [1,2]. However, the long-term gas production from these reservoirs is known to be a function of fluid transport in the shale matrix and strongly influenced by the fluid transport process in the inorganic matrix, kerogen and fractures [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Impact of Local Effects on the Evolution of Unconventional Rock Permeability

Ma¹,

Li²,

Zhang

et al. 2019

Energies

Self Cite

View full text Add to dashboard Cite

When gas is extracted from unconventional rock, local equilibrium conditions between matrixes and fractures are destroyed and significant local effects are introduced. Although the interactions between the matrix and fracture have a strong influence on the permeability evolution, they are not understood well. This may be the reason why permeability models in commercial codes do not include the matrix-fracture interactions. In this study, we introduced the local force to define the interactions between the matrix and the fracture and derived a set of partial differential equations to define the full coupling of rock deformation and gas flow both in the matrix and in the fracture systems. The full set of cross-coupling formulations were solved to generate permeability evolution profiles during unconventional gas extraction. The results of this study demonstrate that the contrast between the matrix and fracture properties controls the processes and their evolutions. The primary reason is the gas diffusion from fractures to matrixes. The diffusion changes the force balance, mass exchange and deformation.

show abstract

A fully coupled multiscale shale deformation-gas transport model for the evaluation of shale gas extraction

Cited by 130 publications

References 34 publications

Numerical simulation of a coupled gas flow and geomechanics process in fractured coalbed methane reservoirs

Numerical simulation of a coupled gas flow and geomechanics process in fractured coalbed methane reservoirs

MRST-Shale: An Open-Source Framework for Generic Numerical Modeling of Unconventional Shale and Tight Gas Reservoirs

Impact of Local Effects on the Evolution of Unconventional Rock Permeability

Contact Info

Product

Resources

About