Interactions of multiple processes during CBM extraction: A critical review

Liu, Jishan; Chen, Zhongwei; Elsworth, Derek; Qu, Hao; Chen, Dong

doi:10.1016/j.coal.2011.06.004

Cited by 366 publications

(153 citation statements)

References 73 publications

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“…Furthermore, permeability is closely related to the cleat system of coal (Baghbanan and Jing, 2008;Liu et al, 2011;Somerton et al, 1975). As shown in Fig.…”

Section: Accepted M Manuscriptmentioning

confidence: 93%

Characterisation of mechanics and flow fields around in-seam methane gas drainage borehole for preventing ventilation air leakage: A case study

Zheng

Chen

Kizil

et al. 2016

International Journal of Coal Geology

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Coal Mine Methane (CMM) drainage via adopting in-seam horizontal boreholes is an effective way to decrease ventilation cost and production delay, ensure mining safety, reduce greenhouse gas emissions and increase the supply of energy resource.Ventilation air leakage into borehole, however, occurs frequently, which decreases the methane-drainage efficiency. Despite extensive anti-leakage method investigations, a very few studies have been focused on spraying air-proof materials on the roadway rib and optimizing borehole sealing along the borehole, along with taking the effects of sequential excavations of roadway and borehole into account. In this paper, based on data of a real coal mine, a fully coupled mathematical model was developed by incorporating coal permeability with coal mechanical properties and gas adsorption/desorption and was then implemented into a Finite Element software. This numerical simulation was used to analyse transient stress and dynamic air-leakage flow fields around the drainage borehole. Simulation results indicate that: (1) Four stress areas (І to IV) exist around the roadway based on different relief status of the tri-axial stress, and stress distributions around the borehole in those four areas are different from each other; (2) Based on different air-leakage degrees, on the roadway rib, there are four air-leakage levels around borehole. Meanwhile, there are four leakage areas along the borehole: FAA, SAA, HAA and VAA, and the optimal sealing length should be over 17m (exceeding HAA) to prevent air leakage. Air-leakage results in (2) are verified mutually with the mechanics outcomes in (1). Meanwhile, real data obtained from field experiments is introduced to validate the simulation results. All those outcomes can allow for the optimal design of the spraying area and order and borehole sealing, thus provide scientific basis for an integrated anti-air-leakage method including spraying air-proof materials on the roadway wall and sealing borehole effectively, to prevent ventilation air leakage and maximize methane drainage performance.

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“…Furthermore, permeability is closely related to the cleat system of coal (Baghbanan and Jing, 2008;Liu et al, 2011;Somerton et al, 1975). As shown in Fig.…”

Section: Accepted M Manuscriptmentioning

confidence: 93%

Characterisation of mechanics and flow fields around in-seam methane gas drainage borehole for preventing ventilation air leakage: A case study

Zheng

Chen

Kizil

et al. 2016

International Journal of Coal Geology

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“…The importance of sorption, permeability, multiple influencing factors, and relative permeability in coal seams are discussed in detail in various publications (e.g. Saulsberry et al, 1996;Karacan, 2008;Busch and Gensterblum, 2011;Liu et al, 2011;Clarkson et al, 2011). In addition, the effects of various mining and coal reservoir properties on potential emissions into mine workings during development mining of coal seams are discussed in Karacan (2008) using dynamic reservoir simulation.…”

Section: Significance and Objectivementioning

confidence: 99%

Production history matching to determine reservoir properties of important coal groups in the Upper Pottsville formation, Brookwood and Oak Grove fields, Black Warrior Basin, Alabama

Karacan

2013

Journal of Natural Gas Science and Engineering

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The Black Warrior Basin of Alabama is one of the most important coal mining and coalbed methane production areas in the United States. Methane control efforts through degasification that started almost 25 years ago for the sole purpose of ensuring mining safety resulted in more than 5000 coalbed methane wells distributed within various fields throughout the basin. The wells are completed mostly in the Pratt, Mary Lee, and Black Creek coal groups of the Upper Pottsville formation and present a unique opportunity to understand methane reservoir properties of these coals and to improve their degasification performances.The Brookwood and Oak Grove fields in the Black Warrior Basin are probably two of the most important fields in the basin due to current longwall coal mining activities. In this work, methane and water productions of 92 vertical wellbores drilled, some completed 20 years ago, over a current large coal mine district located in these two fields, were analyzed by history matching techniques. The boreholes were completed at the Mary Lee coal group, or at combinations of the Pratt, Mary Lee, and Black Creek groups. History matching models were prepared and performed according to properties of each coal group.Decline curve analyses showed that effective exponential decline rates of the wells were between 2% and 25% per year. Results of production history matching showed, although they varied by coal group, that pressure decreased as much as 80% to nearly 25 psi in some areas and resulted in corresponding decreases in methane content. Water saturation in coals decreased from 100% to between 20 and 80%, improving gas relative permeabilities to as much as 0.8. As a result of primary depletion, permeability of coal seams increased between 10 and 40% compared to their original permeability, which varied between 1 and 10 md depending on depth and coal seam. These results not only can be used for diagnostic and interpretation purposes, but can be used as parameter distributions in probabilistic simulations, as illustrated in the last section of this paper. They can also be used in conjunction with spatial modeling and geological considerations to calculate potential methane emissions in operating mines.

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“…Analogue CSG sensitivity studies suggests the geological parameters which most significantly control reservoir performance are permeability, gas content and saturation, and coal layer thickness and lateral continuity . Similar to conventional gas fields, permeability is central to controlling the deliverability of CSG wells; however, in CSG fields, reservoir scale permeability is predominantly achieved via a network of fractures termed cleats (Liu et al 2011). As water is pumped out reservoir pressure is reduced to below the critical desorption pressure, allowing gas to diffuse into the cleat network where it will flow in a manner described by Darcy's Law.…”

Section: Surat Basin Coals As Csg Reservoirsmentioning

confidence: 99%

“…The permeability of fractures cannot be reliably measured in the lab and instead field based pressure transient analysis (e.g. build-up, fall-off test) is required to estimate the aggregate permeability of the reservoir (Liu et al 2011). In most high rank coals (e.g.…”

Section: Permeabilitymentioning

confidence: 99%

An investigation of numerical facies models for coal seam gas reservoirs; Walloon Subgroup, Surat Basin

Shields¹

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The Walloon Subgroup (WSG) represents a prolific coal seam gas (CSG) resource which, in part, underpins three large CSG to liquefied natural gas (LNG) projects operating along the Australian east coast. These mega-projects require long term forecasts of gas production, predictions which are often derived via the dynamic simulation of numerical reservoir models. Reservoir models consist of hierarchical collections of inter-related rock and fluid parameters. The facies model, representing palaeogeography, serves as the foundation of this linkage as it defines the three-dimensional (3D) geometry and distribution of coal seams. This thesis is comprised of complimentary studies aimed at investigating and enhancing the predictive capability of numerical facies models in the Walloon Subgroup.A preliminary screening study investigates CSG production behaviours to understand how reservoir parameters, including the distribution and continuity of coal layers, impact the predictions output by reservoir models. A database of open-source reservoir properties was compiled and used to construct representative reservoir models for three CSG development areas present along the WSG productive fairway in the eastern Surat Basin. Simulation experiments using these models confirms that the distribution and lateral continuity of coal facies are a significant control upon the late-stage production behaviour of CSG wells -a finding which provides impetus for further detailed investigation of WSG facies models.Construction of predictive facies models requires a comprehensive understanding of regional depositional trends, local facies architectures and depositional processes as well as computer routines able to translate this information into numerical 3D grids. Present gaps in the industry's understanding of the WSG highlight the requirement for further studies aimed at 1) refinement of the WSG's regional stratigraphic and palaeogeographic models, 2) delineation of the WSG's reservoir scale internal alluvial architecture, 3) identification of the processes or mechanisms controlling reservoir-scale facies relationships within the WSG and 4) development of workflows better able to represent alluvial facies in numerical reservoir models. The focus of this dissertation is to explore these conceptual gaps leading to improved numerical facies models of the WSG.Investigation of WSG facies models began with a regional study integrating newly available borehole image log data with sedimentological interpretations from cored wells and regional correlations to test and refine existing basin-wide palaeogeographic models for the WSG. This analysis offers a glimpse into fluvial styles and palaeoflow orientations present within the basin's interior and was 2 used to identify regional trends describing the spatial and temporal distribution of alluvial depositional styles. Synthesis of stratigraphic, sedimentological and palaeoflow interpretations developed during this study suggests the presence of a SE oriented trunk drainage system during depo...

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Interactions of multiple processes during CBM extraction: A critical review

Cited by 366 publications

References 73 publications

Characterisation of mechanics and flow fields around in-seam methane gas drainage borehole for preventing ventilation air leakage: A case study

Characterisation of mechanics and flow fields around in-seam methane gas drainage borehole for preventing ventilation air leakage: A case study

Production history matching to determine reservoir properties of important coal groups in the Upper Pottsville formation, Brookwood and Oak Grove fields, Black Warrior Basin, Alabama

An investigation of numerical facies models for coal seam gas reservoirs; Walloon Subgroup, Surat Basin

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