A dynamic-pulse pseudo-pressure method to determine shale matrix permeability at representative reservoir conditions

Fan, Kunkun; Dong, Mingzhe; Elsworth, Derek; Li, Yajun; Yin, Chuancun; Li, Yanchao

doi:10.1016/j.coal.2018.04.011

Cited by 20 publications

(15 citation statements)

References 61 publications

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“…The permeability of sediments is an important parameter for the experimental and numerical simulation of in situ gas hydrate extraction (Wang et al, ). Permeability, which describes the seepage capacity of fluid in porous media, determines the recovery efficiency of gas and water (Fan et al, ). Hydrate exists as a solid in the pores of porous media.…”

Section: Introductionmentioning

confidence: 99%

Study on the Effects of Heterogeneous Distribution of Methane Hydrate on Permeability of Porous Media Using Low‐Field NMR Technique

Hou

Zhao

et al. 2020

JGR Solid Earth

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The permeability of sediments is an important parameter that effects flow characteristics of the gas and water in the process of natural gas hydrates development. The distribution of gas hydrate is generally heterogeneous in porous media. It poses a great challenge to the permeability measurement of hydrate‐bearing sediments. To study the effect of heterogeneous distribution of methane hydrate on the permeability of porous media, methane hydrate formation in the sandstone and permeability measurement was carried out using a low‐field nuclear magnetic resonance (NMR) measurement system in situ conditions. The spatial distribution of methane hydrate in the core samples was determined by combining the T2 distribution with magnetic resonance imaging. The results show that the distribution of methane hydrate is heterogeneous in the core samples. The temporal and spatial variation of permeability happens in the process of hydrate dissociation. The heterogeneity of methane hydrate distribution severely affects the analysis of permeability change. Considering the heterogeneity of methane hydrate distribution, a new method was proposed to obtain the quantitative relationship between hydrate saturation and relative permeability based on magnetic resonance imaging and the equivalent seepage capacity method. The results show that the relative permeability models obtained by this method agree better with experimental results. The optimum coefficients of relative permeability models obtained by equivalent seepage capacity method change significantly in contrast with the direct fitting method. The variation of the optimum coefficient is up to 300% in this study. The model coefficients are related to the pore characteristic of hydrate‐free porous media.

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Section: Introductionmentioning

confidence: 99%

Study on the Effects of Heterogeneous Distribution of Methane Hydrate on Permeability of Porous Media Using Low‐Field NMR Technique

Hou

Zhao

et al. 2020

JGR Solid Earth

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“…Previous studies indicate that a linear relationship between pseudo-pressure m(P) and pressure P appears during the primary half stage of the pressure drop (Ettehadtavakkol and Jamali, 2016;Fan et al, 2018b). If the gas desorption capacity ρ wads -P curve at each substantive production stage can be described linearly, the F D -m(t) relationship can be approximated as (Crank, 1975;Ettehadtavakkol and Jamali, 2016):…”

Section: Permeability Determinationmentioning

confidence: 99%

“…Both average absolute error (AAE) and average absolute relative error (AARE) are used to estimate the accuracy of the calculated results, which are defined as (Feng et al, 2014;Fan et al, 2018b):…”

Section: Permeability Determinationmentioning

confidence: 99%

Radial Permeability Measurements for Shale Using Variable Pressure Gradients

Fan

Sun²,

Elsworth

et al. 2020

Acta Geologica Sinica (Eng)

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Shale gas is becoming an important component of the global energy supply, with permeability a critical controlling factor for long‐term gas production. Obvious deviation may exist between helium permeability determined using small pressure gradient (SPG) methods and methane permeability obtained under actual field production with variable pressure gradients (VPG). In order to more accurately evaluate the matrix permeability of shale, a VPG method using real gas (rather than He) is established to render permeability measurements that are more representative of reservoir conditions and hence response. Dynamic methane production experiments were performed to measure permeability using the annular space in the shale cores. For each production stage, boundary pressure is maintained at a constant and the gas production with time is measured on the basis of volume change history in the measuring pump. A mathematical model explicitly accommodating gas desorption uses pseudo‐pressure and pseudo‐time to accommodate the effects of variations in pressure‐dependent PVT parameters. Analytical and semi‐analytical solutions to the model are obtained and discussed. These provide a convenient approach to estimate radial permeability in the core by nonlinear fitting to match the semi‐analytical solution with the recorded gas production data. Results indicate that the radial permeability of the shale determined using methane is in the range of 1×10−6 – 1×10−5 mD and decreases with a decrease in average pore pressure. This is contrary to the observed change in permeability estimated using helium. Bedding geometry has a significant influence on shale permeability with permeability in parallel bedding orientation larger than that in perpendicular bedding orientation. The superiority of the VPG method is confirmed by comparing permeability test results obtained from both VPG and SPG methods. Although several assumptions are used, the results obtained from the VPG method with reservoir gas are much closer to reality and may be directly used for actual gas production evaluation and prediction, through accommodating realistic pressure dependent impacts.

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“…e relation between permeability and porosity is described by the cubic law, which can be expressed as follows [27][28][29]:…”

Section: Porosity and Permeability Of The Unloading Coal Seammentioning

confidence: 99%

Rational Boreholes Arrangement of Gas Extraction from Unloaded Coal Seam

Fan

Sheng

Zhang

et al. 2018

Advances in Civil Engineering

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In order to enhance gas extraction from unloaded coal seam by drilling borehole in the floor roadway, the mechanism of stress relief improving permeability by protective coal seam mining was analyzed. Based on the multiphysics field theory, the hydraulic-mechanical coupling model of gas extraction in the unloading coal seam was established, and the gas extraction process by drilling borehole in the floor roadway in the overburden of Panyi Coal Mine 1551 (1) panel was simulated. The influence of different drilling arrangements on the gas extraction effect was analyzed. The results show that the permeability of protected coal seams is characterized by zoning and can be divided into the permeability-enhanced zone, the permeability-reduced zone, and the original permeability zone according to the stress state of coal seam. Under the condition of uniform borehole distribution, the gas pressure decreased slowly in the permeability-reduced zone and is still greater than 0.74 MPa after 180 days of extraction, and there is a large extraction blind area in the protected panel. Under the condition of nonuniform borehole distribution arrangement according to the characteristics of permeability zoning, the effective extraction area can almost cover the protected panel, and the blind extraction area is reduced by 91.22% when compared to uniform borehole distribution. These can provide a reference for unloading gas extraction under similar conditions.

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A dynamic-pulse pseudo-pressure method to determine shale matrix permeability at representative reservoir conditions

Cited by 20 publications

References 61 publications

Study on the Effects of Heterogeneous Distribution of Methane Hydrate on Permeability of Porous Media Using Low‐Field NMR Technique

Study on the Effects of Heterogeneous Distribution of Methane Hydrate on Permeability of Porous Media Using Low‐Field NMR Technique

Radial Permeability Measurements for Shale Using Variable Pressure Gradients

Rational Boreholes Arrangement of Gas Extraction from Unloaded Coal Seam

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