Spontaneous imbibition and wettability characteristics of Powder River Basin coal

Chaturvedi, Tanmay; Schembre, J.M.; Kovscek, Anthony R.

doi:10.1016/j.coal.2008.08.002

Cited by 69 publications

(45 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the above researchers used instrumental analysis methods to describe in detail the factors that inuence the wettability of coal and coal products in terms of nitrogen/ oxygen-containing functional groups, the dimensions of coal samples, the CO 2 content in coal and electrostatic interactions, [16][17][18][19] studies concerning relationships between the carbon chain structure on the surface of coal dust, carbon/oxygencontaining functional groups in coals and wettability still lack specicity.…”

Section: -5mentioning

confidence: 99%

Analysis of the microscopic mechanism of coal wettability evolution in different metamorphic states based on NMR and XPS experiments

Zhou

Han

2017

RSC Adv.

View full text Add to dashboard Cite

To investigate the evolution of carbon-and oxygen-containing groups during metamorphism and the influence of the structural variation of coal on its wettability, NMR and XPS were employed to study the two main elements, carbon and oxygen, in coal dust. Our results show that with an increase of the metamorphic degree, the number of highly reactive hydroxyl and carboxyl groups show a descending trend whereas the number of low reactivity ether and carbonyl groups increases. The number of carboncontaining groups gradually increases when the metamorphic degree increases, due to a clustering change process which includes an increase in the number of aromatic carbons (Ar-C, H) and a simultaneous decrease in the number of carboxyl carbons (-COOH), methylene carbons (CH 2 ) and ether based carbons (Ar-O, R-O). The reduction rate of carboxyl carbon (-COOH) is closest to the growth rate of aromatic carbon (Ar-C, H). The methyl (CH 3 ) and carboxyl (C]O) carbon evolve discontinuously with the metamorphic degree, which is different from the other carbon groups. Linearregression analysis suggests that the correlation coefficients between aromatic (Ar-C, H), ether (R-O), methylene (CH 2 ) and carboxyl (-COOH) carbons and wettability are 0.98, 0.97, 0.96 and 0.92, respectively, indicating that the main contribution to the wettability from carbon-containing groups comes from these groups. In contrast, hydroxyl oxygen (-OH) has a correlation coefficient as high as 0.98, and is a major contributor from the oxygen-containing groups.

show abstract

Section: -5mentioning

confidence: 99%

Analysis of the microscopic mechanism of coal wettability evolution in different metamorphic states based on NMR and XPS experiments

Zhou

Han

2017

RSC Adv.

View full text Add to dashboard Cite

show abstract

“…(1). On the other side, laboratory experiments on coal samples reported in the literature (Chaturvedi, 2009;Stopa, 1990) show that for small time, the mass of water imbibed by coal is proportional to square root of t. This corresponds to eq. (1) and moreover, this make it possible to obtain the C L experimentally (Stopa, 1990).…”

Section: Previous Workmentioning

confidence: 99%

“…During primary operations, coal is dewatered to initiate and accelerate methane desorption. However, the re-saturation of coal with water following CO 2 enhanced recovery operations is critical to the long-term, secure retention of CO 2 in the subsurface (Chaturvedi, 2009).…”

Section: Introductionmentioning

confidence: 99%

Analytical Model of Water Flow in Coal with Active Matrix

Siemek¹,

Stopa²

2014

Archives of Mining Sciences

View full text Add to dashboard Cite

This paper presents new analytical model of gas-water flow in coal seams in one dimension with emphasis on interactions between water flowing in cleats and coal matrix. Coal as a flowing system, can be viewed as a solid organic material consisting of two flow subsystems: a microporous matrix and a system of interconnected macropores and fractures. Most of gas is accumulated in the microporous matrix, where the primary flow mechanism is diffusion. Fractures and cleats existing in coal play an important role as a transportation system for macro scale flow of water and gas governed by Darcy's law. The coal matrix can imbibe water under capillary forces leading to exchange of mass between fractures and coal matrix. In this paper new partial differential equation for water saturation in fractures has been formulated, respecting mass exchange between coal matrix and fractures. Exact analytical solution has been obtained using the method of characteristics. The final solution has very simple form that may be useful for practical engineering calculations. It was observed that the rate of exchange of mass between the fractures and the coal matrix is governed by an expression which is analogous to the Newton cooling law known from theory of heat exchange, but in present case the mass transfer coefficient depends not only on coal and fluid properties but also on time and position. The constant term of mass transfer coefficient depends on relation between micro porosity and macro porosity of coal, capillary forces, and microporous structure of coal matrix. This term can be expressed theoretically or obtained experimentally.Keywords: two-phase flow, coal, imbibition, mathematical modeling, analytical solution W artykule zaprezentowano nowy model matematyczny przepływu wody i gazu w jednowymiarowej warstwie węglowej z uwzględnieniem wymiany masy między systemem szczelin i matrycą węglową. Węgiel jako system przepływowy traktowany jest jako układ o podwójnej porowatości i przepuszczalności, składający się z mikroporowatej matrycy węglowej oraz z systemu szczelin, spękań i ewentualnie największych porów. Przepływowi w systemie szczelin towarzyszyć może wymiana masy z matrycą, której intensywność zależy m.in. od właściwości węgla i warunków panujących w układzie przepływowym. W szczególności matryca węglowa może pochłaniać wodę pod wpływem sił kapilarnych, co wpływa na przepływ w szczelinach. W artykule zostało zaproponowane równanie różniczkowe cząstkowe opisujące nasycenie wodą w systemie szczelin z uwzględnieniem wymiany masy z matrycą pod wpływem sił kapilarnych. Podano dokładne rozwiązanie analityczne, które może być zastosowane w praktyce inżynierskiej. Zauważono, że szybkość wymiany masy między szczelinami i matrycą wyraża się formułą analogiczną do prawa stygnięcia Newtona, ale w analizowanym przypadku współczynnik wymiany masy zależy nie tylko od właściwości węgla i płynów ale również od położenia i czasu. Stały człon tego współczynnika może być obliczony teoretycznie lub wyznaczony eksperymentalnie.Słowa kluczowe: prz...

show abstract

“…Figure 2.14: Sessile drop contact angle measurements which show increased water wettability of coal with an increased fluid pH (Chaturvedi et al, 2009).…”

Section: Relative Permeability Curvesmentioning

confidence: 99%

“…Experimentally measured relative permeability using coal cores in the laboratory under steady or unsteady methods detail a cross-point water saturation fraction in the relative permeability curve exceeding 0.5, implying coal is water wet (Conway et al, 1995a;Durucan et al, 2013;Ham and Kantzas, 2011;Purl et al, 1991;Rahman and Khaksar, 2007;Shen et al, 2011 (Kaveh et al, 2012;Saghafi et al, 2014), gas desorption (Ham and Kantzas, 2008;Ham and Kantzas, 2011), mineral matter (Gosiewska et al, 2002b) and liquid characteristics including ion concentration (Albijanic et al, 2010;Mishra et al, 2002) and pH (Chaturvedi et al, 2009). Coal rank is also another important factor that contributes to coal wettability, as high rank coal, such as anthracite are not water-wet, yet low rank coal like peat has both a high moisture content and is waterwet (Moore, 2012).…”

Section: Research Problemmentioning

confidence: 99%

The Effect of Water Occlusion on Gas Production in Coal

Mahoney¹

View full text Add to dashboard Cite

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...

show abstract

Spontaneous imbibition and wettability characteristics of Powder River Basin coal

Cited by 69 publications

References 11 publications

Analysis of the microscopic mechanism of coal wettability evolution in different metamorphic states based on NMR and XPS experiments

Analysis of the microscopic mechanism of coal wettability evolution in different metamorphic states based on NMR and XPS experiments

Analytical Model of Water Flow in Coal with Active Matrix

The Effect of Water Occlusion on Gas Production in Coal

Contact Info

Product

Resources

About