Coal bed

The unconventional reserves of natural gas occur principally in the form of recoverable methane from coal beds. As of 1991, reserves of coal bed methane totaled 8.6 EJ (8.2 x 10 Btu), principally in the states of Alabama, Colorado, and New Mexico (16). 

The gas reservoirs located ia very deep waters, ia coal beds, and ia tight sands are now more accessible. Fifteen percent of the U.S. gas supply ia 1992 was derived from tight sand formations and 1.4 x 10 of coal-bed methane was added to the proven reserves (22). In 1992, U.S. proven reserves were placed at 4.67 x 10 ia the lower 48 states, and it was estimated that the identified gas resource ia the United States and Canada exceeds 3.4 X 10. Based on the 1992 rate of natural gas consumption, the United States has between 8 and 10 years of proven reserves and a domestic... 

There are, however, a variety of other sources of methane that have been considered for fuel supply. Eor example, methane present in coal (qv) deposits and formed during mining operations can form explosive mixtures known as fire damp. In Western Europe, some methane has been recovered by suction from bore holes drilled in coal beds and the U.S. Bureau of Mines has tested the economic practicaUty of such a system. Removal of methane prior to mining the coal would reduce explosion ha2ards associated with coal removal. As much as 11.3 x 10 (400 trillion (10 ) cubic feet or 400 TCE) of... 

The first commercial operation of the Lurgi process was in Germany in 1936 using brown coal. The reactor was modified to stir the coal bed to permit utilization of bituminous coal. One plant was built at the Dorsten Works of Steinkohlengas AG, and the Sasol plants were built in South Africa to provide synthesis gas for Hquid fuels. 

The three main types of reactors shown in Fig. 27-6 are in aclual commercial use the moving bed, the fluidized bed, and the entrained bed. The moving bed is often referred to as a. fixed bed because the coal bed is kept at a constant height. These differ in size, coal feed, reactant and product flows, residence time, and reaction temperature. 

Non-conventional gas is natural gas found in unusual underground conditions, such as very impermeable reservoirs which require massive stimulation in order to be recovered, or in underground occurrences of gas hydrates, or dissolved in formation water, or coal-bed methane, or gas from in-situ gasification of coal. 

Carboniferous 345 Myr Climate cools, marked latitudinal gradients. Extensive forests of early vascular plants, especially club mosses, horsetails, ferns. Coal beds form. Amphibians diversify first reptiles appear. Radiation of early insect orders... 

The production of natural gas from coal typically requires a stimulation with hydraulic fracturing. Basic studies on the effectiveness of various treatment methods for coal-beds have been presented in the literature [398,1424]. 

To estimate the large-scale storage capacity of 45 important coal basins during Enhanced Coal Bed Methane Recovery (ECBM) in China, Li et al. used an equation which can be modified to a simpler form without considering the different coal bed basins [63, 79]. 

In coal bed capacity estimation, the Langmuir equation provides a simple and efficient relation for single layer low-pressure conditions. In the case of high pressure and high temperature, Bi Langmuir, extended Langmuir, Sips, Langmuir-Freundlich, Toth, UNILAN, two-dimensional... 

PhungQ.H., Kyuro S., et al. Numerical simulation of C02 enhanced coal bed methane recovery for a Vietnamese coal seam. 2010 Journal of Novel Carbon Resource Science 2 1-7. 

The changes that occur with solid residence time in the hot-rod reactor were not very pronounced because only the nonvolatile portion of the oil remaining on the coal bed would be expected to undergo secondary reactions such as aromatization and loss of heteroatoms. However, the oils from the hot-rod reactor were also compared with those obtained in a rotating autoclave with much longer solid and vapour residence times and the changes with residence time were more noticeable in this case as can be seen in Table II. 

Displacing the methane tied up in deep unmineable coal adds another small carbon sink to the portfolio of options and this process is called enhanced coal bed methane recovery. When injected into a coal bed, C02 can replace adsorbed methane. By doing so, coal beds can serve as a C02 reservoir and a source for methane production (Parson and Keith, 1998). This method is attractive in the sense that most of the injected C02 will be immobilized by either physical or chemical adsorption on the coal surface. 

Just as oil, natural gas is also categorised as conventional and unconventional. Unlike crude oil, however, natural gas deposits are normally classified according to the economic or technical approach, i.e., all occurrences that are currently extract-able under economic conditions are considered conventional, whereas the rest are termed unconventional. Conventional natural gas includes non-associated gas from gas reservoirs in which there is little or no crude oil, as well as associated gas , which is produced from oil wells the latter can exist separately from oil in the formation (free gas, also known as cap gas, as it lies above the oil), or dissolved in the crude oil (dissolved gas). Unconventional gas is the same substance as conventional natural gas, and only the reservoir characteristics are different and make it usually more difficult to produce. Unconventional gas comprises natural gas from coal (also known as coal-bed methane), tight gas, gas in aquifers and gas hydrates (see Fig. 3.17). It is important to mention in this context so-called stranded gas , a term which is applied to occurrences whose extraction would be technically feasible, but which are located in remote areas that at the moment cannot (yet) be economically developed (see Section 3.4.3.1). 

In fact, coal-bed methane is an explosive hazard in underground mining operations and for safety reasons has traditionally been vented with mines fresh air circulation. Since the 1970s, methane captured from underground mining has increasingly been used to supplement local gas supplies (WEA, 2000). 

Storage in coal seams Storage in salt caverns Storage in abandoned mines Enhanced coal-bed methane production Storage in unminable coal seams... 

Stanton, R., Flores, R., Warwick, P. D., Gluskoter, H. and Strieker, G. D. (2001). Coal bed sequestration of carbon dioxide. Proceedings of the First National Conference on Carbon Sequestration, 14-17 May 2001. Washington, DC. 

Compressed-air energy storage Corporate average fuel economy California Air Resources Board Coal-bed methane Combined cycle gas turbine Carbon/carbon dioxide capture and storage Clean development mechanism Chlorofluorocarbon Computable general equilibrium Compressed gaseous hydrogen Combined heat and power... 

ECBM EGR EIA EOR EPR Enhanced coal-bed methane Enhanced gas recovery Energy Information Administration (US DOE) Enhanced oil recovery European Pressurised Water Reactor Evolutionary Power Reactor... 

Proven reserves of conventionally reservoired natural gas in the United States total about 5.35 Tm (189 Tft ). An additional 0.53 Tm (18.7 Tft ) of proven reserves are in coal bed methane deposits. Production in 2003 was about 0.54 Tm (19.1 Tft ), over 75 percent... 

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