Relative permeabilities of gas and water for different rank coals

Shen, Jian; Qin, Yong; Wang, Geoff; Fu, Xuehai; Wei, Chongtao; Bo, Lei

doi:10.1016/j.coal.2011.03.001

Cited by 97 publications

(60 citation statements)

References 31 publications

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“…The two well-known relatively permeability models of Brooks and Corey (1966) and Van Genuchten (1980), have been developed for unconsolidated and consolidated porous media, respectively. Laboratory experiments have been conducted to investigate the permeability of different coal with steady-state and unsteady-state methods (Durucan et al, 2013;Shen et al, 2011). In another approach, relative permeability has been determined by history matching with field production data (Zhou, 2012).…”

Section: Highlightmentioning

confidence: 99%

Fully coupled two-phase flow and poromechanics modeling of coalbed methane recovery: Impact of geomechanics on production rate

Rutqvist

Oldenburg

et al. 2017

Journal of Natural Gas Science and Engineering

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This study presents development and application of a fully coupled two-phase (methane and water) and poromechanics numerical model for the analysis of geomechanical impact on coalbed methane (CBM) production. The model considers changes in two-phase fluid flow properties, i.e., coal porosity, permeability, water retention, and relative permeability curves through changes in cleat fractures induced by effective stress variations and desorptioninduced shrinkage. The coupled simulator is first verified for poromechamics coupling and simulation parameters of a CBM reservoir model are calibrated by history matching against one year of CBM production field data from Shanxi Province, China. Then, the verified simulator and calibrated CBM reservoir model are used for predicting the impact of geomechanics on production rate for twenty years of continuous CBM production. The simulation results show that desorption-induced shrinkage is the dominant process in increasing permeability in the near wellbore region. Away from the wellbore, desorptioninduced shrinkage is weaker and permeability is reduced by pressure depletion and increased effective stress. A sensitivity analysis shows that for coal with a higher sorption strain, a larger initial Young's modulus and smaller Poisson's ratio promote the enhancement of permeability as well as the production rate. Moreover, the conceptual model of the cleat system, whether dominated by vertical cleats with permeability correlated to horizontal stress or with permeability correlated to mean stress can have a significant impact on the predicted production rate. Overall, the study clearly demonstrates and confirms the critical importance of considering geomechanics for an accurate prediction of CBM production. (1) A fully coupled two-phase flow and poromechanics model for methane recovery (2) Simulation parameters are calibrated by history matching against field data (3) The geomechanics behaviors significantly affect the prediction of CBM production

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Section: Highlightmentioning

confidence: 99%

Fully coupled two-phase flow and poromechanics modeling of coalbed methane recovery: Impact of geomechanics on production rate

Rutqvist

Oldenburg

et al. 2017

Journal of Natural Gas Science and Engineering

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“…Most laboratory studies that report relative permeability in coals measured by steady state or unsteady state core flooding methods derive a crossover point water saturation fraction (S w ) exceeding 0.5, which is usually interpreted as the coal being water wet or hydrophilic (Conway et al, 1995;Durucan et al, 2013;Ham and Kantzas, 2011;Purl et al, 1991;Rahman and Khaksar, 2007;Shen et al, 2011). However, a problem with this standard approach is that it reports an average relative permeability for the core which assumes that the core has a uniform composition, homogenous wetting state and that the effects of capillary pressures are negligible.…”

Section: Introductionmentioning

confidence: 99%

The effect of rank, lithotype and roughness on contact angle measurements in coal cleats

Mahoney

Rufford

Johnson

et al. 2017

International Journal of Coal Geology

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“…For such flow systems it may be more appropriate to use straight-line relative permeability relationships since capillary effects are considered negligible in segregated flow. Shen et al (2011) investigated the relative permeabilities to gas and water in different rank coals selected from South Qinshui Basin, China under various gas/water saturations through water replacement with methane using an unsteady-state method.…”

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confidence: 99%