Cleats and their relation to geologic lineaments and coalbed methane potential in Pennsylvanian coals in Indiana

Solano-Acosta, Wilfrido; Mastalerz, María; Schimmelmann, Arndt

doi:10.1016/j.coal.2007.02.004

Cited by 81 publications

(27 citation statements)

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“…They identified four groups of cleats that correspond to the following: Group 1 and 2 are macrocleats, measured in deci-and centimetres, respectively; Group 3 consists of mesocleats, measured in millimetres; and Group 4 are microcleats, measured in micrometers (cf. table 1 of Solano-Acosta et al, 2007). In the present study, only macrocleats belonging mainly to Group 2 of Ammosov & Eremin (1963) are described.…”

Section: Genetic Cleat Classificationmentioning

confidence: 73%

“…This is in contrast to hard coal, which are intensively examined, among other reasons because they contain coalbed methane -CBM (e.g. McCulloch et al, 1974McCulloch et al, , 1976Close & Mavor, 1991;Close, 1993;Law, 1993;Karacan & Okandan, 2000;Su et al, 2001;Solano-Acosta et al, 2007;Dawson & Esterle, 2010;Paul & Chatterjee, 2011). The present contribution is the first to focus purely on discontinuities within the Miocene MPLS-1 of central Poland.…”

Section: Introductionmentioning

confidence: 85%

“…In contrast, the latter type represents cleats resulting from external forces such as tectonics. Regardless of the suggested 'endogenic' processes, at least the cleat orientation seems to be controlled by the tectonic stress field (Laubach et al, 1998;Su et al, 2001;Solano-Acosta et al, 2007;Dawson & Esterle, 2010;Paul & Chatterjee, 2011; and references therein).…”

Section: Genetic Cleat Classificationmentioning

confidence: 99%

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What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

Widera

2014

Geologos

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Cleats (fractures, joints) are discontinuities in coals, including lignites. They are important in mining activity because of their gas and water permeability in hard coal, and mainly because of their water permeability in lignites. As opposed to hard-coal cleats, lignite cleats have not been studied in detail before. The present contribution does so, using as an example the 1st Middle-Polish Lignite Seam (MPLS-1) in the Jóźwin IIB opencast mine in central Poland. It should be mentioned here that any remarks in the present contribution concerning MPLS-1 refer exclusively to this lignite seam in the Jóźwin IIB opencast mine.The investigated discontinuities consist of two sets, i.e. the face and butt cleats, which are roughly oriented NW-SE and NE-SW, respectively. The mean spacing of the face cleats is ~12.4 cm, while the mean spacing of the butt cleats is ~12.8 cm. The maximum average aperture is ~4.9 mm for the face cleats and ~4.1 mm for the butt cleats. The cleat spacing and aperture do not depend on the lignite thickness, but the cleat spacing increases with increasing mineral-matter and xylite content, whereas the aperture increases when the contents decrease. The regional folding and local salt diapirism tentatively explain the formation of the orthogonal system of the lignite cleats, partly because of the parallelism of the face cleats and the major tectonic directions in central Poland.

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Section: Genetic Cleat Classificationmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 85%

Section: Genetic Cleat Classificationmentioning

confidence: 99%

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What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

Widera

2014

Geologos

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“…A typical micro-cleat aperture range is between 6-250 µm (Dawson and Esterle, 2010;Kumar et al, 2011;Laubach et al, 1998;Mazumder et al, 2006;Solano-Acosta et al, 2007). Cleat aperture is contingent upon the opposing effects of: increasing effective net stress (reduction in aperture) and gas desorption from the coal matrix (increase in aperture).…”

Section: General Materials and Methodsmentioning

confidence: 99%

“…Blockage B demonstrates a scenario where the gas pressure is insufficient to rupture S. Thus preferential flow pathways are created in the cleat network. Figure taken from Teng et al (2016 The focus on the micro-cleat, which can range from 6-260 μm (Dawson and Esterle, 2010;Kumar et al, 2011;Laubach et al, 1998;Mazumder et al, 2006;Solano-Acosta et al, 2007), was selected in this thesis for several reasons. 1) Surface wettability which may induce a residual liquid film will have a greater influence on the absolute flow permeability of micro-cleats compared to larger fractures.…”

Section: Research Problemmentioning

confidence: 99%

The Effect of Water Occlusion on Gas Production in Coal

Mahoney¹

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Relative permeability is of fundamental importance to understand and model the flow of hydrocarbons and water in porous rocks including coal, and thus relative permeability is critical in prediction of commercial gas and water production rates from coal seam gas (CSG) reservoirs.Despite relative permeability being a primary parameter for determining reservoir performance, the fundamental physics of how or where water may occlude or block cleats in a coal seam, and thereby interfere with gas production rates, is not fully understood. This project aims to improve the understanding of water occlusion in CSG reservoirs through fluid experiments with model coal cleats and to evaluate the potential impact of water occlusion of reservoir performance.The aim of this thesis is to develop a new experimental methodology that can be used identify the main control factors that affect wettability in coal. There are two key objectives to satisfy the thesis aim 1) develop methods to make artificial channels in coal and 2) create a world first microfluidic device that assess micro scale flow through coal cleats, known as the cleat flow cell (CFC). The initial features to be evaluated will include: lithotype, surface roughness, surface composition, specifically chemical functional groups and pressure. oxygen plasma with a photolithography process to make the desired pattern on coal surface, UV Laser ablation, mechanical machining, a mechanical scratch technique, and a chemical etching technique that used potassium permanganate (KMnO4). Characteristics of the artificial channels were assessed using a surface step profiler, scanning electron microscopy, micro-Raman spectroscopy and light microscopy. A sixth methodology to create an artificial channel using pressed coal powder was also used as a means of evaluating the influence of the surface chemistry on the wetting behaviour, without the interference of surface topography.In Chapter Five, I report the effect of rank and lithotype on the wettability of coal in microfluidic experiments in two types of artificial microchannels; (1) reactive ion etched (RIE) channels and (2) die-cast channels prepared by pressing powdered lithotype concentrates. Contact angles and entry pressures of air and water in the artificial cleats were measured in imbibition experiments performed iii with a CFC. The relative contact angles measured in CFC imbibition experiments were in the range 110 -140° in the RIE channels and 85°-115° in the pressed discs, which are larger contact angles than measured on the flat bulk surfaces of these samples by the conventional sessile drop technique (58°-85°). The CFC observations show that the surface roughness of coal in inertinite-rich dull bands effects contact angle and the entry pressure of the air-water interface differently to the vitrinite-rich bright bands, with both lithotypes presenting unique wetting states. Drainage experiments revealed a thin residual water film on the inertinite cleat wall, not observed on the smoother vitrinite channel. were hydr...

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Refracturing field tests for enhanced coalbed methane production with gas wettability alteration

Lin

Zhao

et al. 2021

Int J Energy Res

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Summary Gas wettability alteration (GWA) technology has been used for better methane drainage underground. Our previous field tests of underground fracturing demonstrated a large increase in coalbed methane (CBM) production compared with those in the boreholes fractured without GWA treatments. However, the general drainage rate of each fracturing borehole with GWA treatment is not high enough because no proppant was used in the underground fracturing. To this end, field tests of surface refracturing in two CBM wells (Wells A‐2 and 4) were conducted with an innovative fracturing measure with GWA treatments and elongated coal‐like proppants in XJ coal mine, Yangquan, China. The water and CBM production with the novel and the conventional fracturing technologies were compared and analyzed. The field test results showed that the CBM production with the novel refracturing technologies (29 697 and 26 844 m3 for Wells XJ‐2 and 4) is greater than those with conventional refracturing (22 746 m3 for Well XJ‐6) and initial‐fracturing (25 297.4 and 2847.2 m3 for Wells XJ‐2 and 4). The significant increase in CBM production demonstrates that the novel fracturing technology could be applied for enhanced CBM production.

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Cleats and their relation to geologic lineaments and coalbed methane potential in Pennsylvanian coals in Indiana

Cited by 81 publications

References 28 publications

What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

The Effect of Water Occlusion on Gas Production in Coal

Refracturing field tests for enhanced coalbed methane production with gas wettability alteration

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