Apparent permeability for gas transport in nanopores of organic shale reservoirs including multiple effects

Wang, Jing; Liu, Huiqing; Wang, Lei; Zhang, Hongling; Luo, Haishan; Gao, Yang

doi:10.1016/j.coal.2015.10.004

Cited by 81 publications

(36 citation statements)

References 46 publications

(68 reference statements)

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“…In addition, all these proposed models do not account for the dynamic changes of stress and adsorption layer as pressure declines (as reflected in Fig.3) in a fractured system, which can significantly overestimate the effects of molecule diffusion on gas production. Recent study (Wang et al 2015b) also reveals that under most real shale-gas-reservoir conditions, gas adsorption and the non-Darcy flow are dominant mechanisms in affecting apparent permeability, while the effects of surface diffusion caused by adsorbed gas can be largely overlooked. So in this article, molecule diffusion will not be discussed in the following derivations for matrix apparent permeability.…”

Section: Shale Gas Apparent Permeability Correctionmentioning

confidence: 99%

What Factors Control Shale-Gas Production and Production-Decline Trend in Fractured Systems: A Comprehensive Analysis and Investigation

Wang

2016

SPE Journal

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SummaryOne of the biggest practical problems with the optimization of shale gas stimulation design is estimating post-fracture production rate, production decline, and ultimate recovery. Without a realistic prediction of the production decline trend resulting from a given completion and reservoir properties, it is impossible to evaluate the economic viability of producing natural gas from shale plays.Traditionally, decline curve analysis (DCA) is commonly used to predict gas production and its decline trend to determine the estimated ultimate recovery (EUR), but its analysis cannot be used to analyze what factors influence the production decline trend due to lack of underlying support of physics, which make it difficult to guide completion designs or optimize field development.In this article, we presented a unified shale gas reservoir model, which incorporates real gas transport, nano-flow mechanisms and geomechanics into fractured shale system. This model is used to predict shale gas production under different reservoir scenarios and investigate what factors control its decline trend. The results and analysis presented in the article provide us a better understanding of gas production and decline mechanisms in a shale gas well with certain conditions of the reservoir characteristics. More in-depth knowledge regarding the effects of factors controlling the behavior of the gas production can help us develop more reliable models to forecast shale gas decline trend and ultimate recovery. This article also reveals that some commonly hold beliefs may sound reasonable to infer production decline trend, but may not be true in a coupled reservoir system in reality. IntroductionWith ever increasing demanding for cleaner energy, unconventional gas reservoirs are expected to play a vital role in satisfying the global needs for gas in the future. The major component of unconventional gas reservoirs comprises of shale gas. Shales and silts are the most abundant sedimentary rocks in the earth's crust and it is evident from the recent year's activities in shale gas plays that in the future shale gas will constitute the largest component in gas production globally, as conventional reservoirs continue declines (Energy Information Administration 2015). According to GSGI, there are more than 688 shales worldwide in 142 basins and 48 major shale basins are located in 32 countries (Newell 2011). Better reservoir knowledge and advancing horizontal drilling and hydraulic fracturing technologies make the production of shale gas resources economically viable and more efficient.

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Section: Shale Gas Apparent Permeability Correctionmentioning

confidence: 99%

What Factors Control Shale-Gas Production and Production-Decline Trend in Fractured Systems: A Comprehensive Analysis and Investigation

Wang

2016

SPE Journal

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“…In addition, all these proposed models do not account for the dynamic changes of stress and adsorption layer as pressure declines (as reflected in Fig.2) in a fractured system, which can significantly overestimate the effects of permeability enhancement on production and production decline trend (Wang 2016c). Recent study (Wang et al 2015b) also reveals that under most real shale-gas-reservoir conditions, gas adsorption and the non-Darcy flow are dominant mechanisms in affecting apparent permeability, while the effects of surface diffusion caused by adsorbed gas can be largely overlooked. So in this article, molecule diffusion will not be discussed in the following derivations for matrix apparent permeability.…”

Section: Correction For Gas Apparent Permeability In Nano-poresmentioning

confidence: 99%

A Numerical Study of Thermal-Hydraulic-Mechanical Simulation With Application of Thermal Recovery in Fractured Shale-Gas Reservoirs

Wang

2016

SPE Reservoir Evaluation &Amp; Engineering

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Shale gas is playing an important role in transforming global energy markets with increasing demands for cleaner energy in the future. One major difference in shale gas reservoirs is that a considerable amount of gas is adsorbed. Up to 85% of the total gas within shale may be found adsorbed on clay and kerogen. How much of the adsorbed gas can be produced has a significant impact on ultimate recovery. Even with improving fracturing and horizontal well technologies, average gas recovery factors in U.S. shale plays is only ~30% with primary depletion. Adsorbed gas can be desorbed by lowering pressure and raising temperature, reservoir flow capacity can be also influenced by temperature, so there is a big prize to be claimed using thermal stimulation techniques to enhance recovery. To date, not much work has been done on thermal stimulation of gas shale reservoirs.In this article, we present general formulations to simulate gas production in fractured shale gas reservoirs for the first time, with fully coupled thermal-hydraulic-mechanical (THM) properties. The unified shale gas reservoir model developed in this study enable us to investigate multi-physics phenomena in shale gas formations. Thermal stimulation of fractured gas reservoirs by heating propped fractures is proposed and investigated. This study provides some fundamental insight into real gas flow in nano-pore space and gas adsorption/desorption behavior in fractured gas shales under various in-situ conditions and sets a foundation for future research efforts in the area of enhanced recovery of shale gas reservoirs.We find that thermal stimulation of shale gas reservoirs has the potential to enhance recovery significantly by enhancing the overall flow capacity and releasing adsorbed gas that cannot be recovered by depletion, but the process may be hampered by the low rate of purely conductive heat transfer, if only the surfaces of hydraulic fractures are heated.

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“…The greatest growth is predicted for shale gas production, increasing from 16% of total production in 2009 to an expected 45% in 2035 in the United States. . However, shale gas reservoir has very low permeability, so the horizontal drilling and the hydraulic fracturing technique have been widely used for increasing the production of shale gas, by increasing the drainage area and creating the artificial fractures, respectively .…”

Section: Introductionmentioning

confidence: 99%

A novel evaluation on fracture pressure in depleted shale gas reservoir

Zhao

Yuan²,

Feng

et al. 2018

Energy Science & Engineering

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Fracture pressure is the key parameter both for horizontal drilling and hydraulic fracturing in the shale gas reservoir. Reservoir depletion will push for the change of the fracture pressure. Previous studies showed that fracture pressure will be decreased with reservoir depletion, which is not suitable for the anisotropic shale gas reservoir. Aiming at resolving this problem, a novel evaluation was established, which can be used to evaluate the influence on fracture pressure of the reservoir depletion, the anisotropy, and the well inclination. The results showed that the fracture pressure will be increased for the strongly anisotropic reservoir with reservoir depletion, and the fracture pressure has a tiny difference between the various anisotropic reservoirs before reservoir depleted, but a larger difference will appear after reservoir depleted, at the later depletion period, the fracture pressure is higher for the stronger anisotropic one. When the anisotropy and the depletion are both the same, the fracture pressure for the higher deviated well is lower. The method and the results can provide a theoretical basis both for the drilling and hydraulic fracturing in depleted shale gas reservoir.

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Apparent permeability for gas transport in nanopores of organic shale reservoirs including multiple effects

Cited by 81 publications

References 46 publications

What Factors Control Shale-Gas Production and Production-Decline Trend in Fractured Systems: A Comprehensive Analysis and Investigation

What Factors Control Shale-Gas Production and Production-Decline Trend in Fractured Systems: A Comprehensive Analysis and Investigation

A Numerical Study of Thermal-Hydraulic-Mechanical Simulation With Application of Thermal Recovery in Fractured Shale-Gas Reservoirs

A novel evaluation on fracture pressure in depleted shale gas reservoir

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