Biogenic gas

Reynolds BC, Frank M, HaUiday AN (2006) Silicon isotope fractionation during nutrient utilization in the North Pacific. Earth Planetary Sci Letters 244 431 143 Rice DD, Claypool GE (1981) Generation, accumulation and resource potential of biogenic gas. Am Assoc Petrol Geol Bull 65 5-25... 

Current hydrated gas estimates are made for biogenic gas associated with in-place generation that tends to be more uniformly distributed. We have no general factual data about the extent of hydrate distribution in the vicinity of submarine seepages (Ginsburg and Soloviev, 1998, p. 165). 

Similarly, if channels are available, biogenic gas may migrate to regions within the hydrate stability envelope. Most of the gas was of biogenic origin in the hydrate core recovered from the Northwest Eileen State Well Number 2, one of the first wells to recover hydrates (Collett, 1983). The biogenic source is likely to predominate for hydrates in permafrost (Kvenvolden, Personal Communication,... 

October 19,1988), in addition to biogenic dominance in ocean hydrates (Dillon and Max, 2000), with sporadic mixtures of biogenic and thermogenic gas in Alaska, Russia, offshore Canada, and the Gulf of Mexico. It is possible to have both means (in place generation and fast fluxes) of supplying biogenic gas, indicated by Kvenvolden et al. (1984) and Kvenvolden and Claypool (1985) at DSDP Site 570 in the Middle America Trench. 

Found by BSR and GHOZ zones Usually structure I, biogenic gas hydrates Usually associated with shales, not fauna Represented by Blake Ridge hydrates... 

The hydrate recovered consisted of methane ( 99%), with minor to trace amounts of carbon dioxide (1.22%), ethane (86 ppmv), propane (2 ppmv), with a volumetric ratio of methane to water of 154. The chlorinity concentration (57.2 mM) of water collected indicated that the sample was a mixture of 10% pore water and 90% freshwater. The gas water ratio exceeded 170, higher than any previously reported for in situ hydrates. The C1/C2 ratio was 11,500, compared to a headspace value three times lower however, both gas ratios indicate biogenic gas. 

Amouroux, D., Roberts, G., Rapsomanikis, S., and Andreae, M. O. (2002) Biogenic gas (CH4, N2O, DMS) emission to the atmosphere from near-shore and shelf waters of the north-western Black Sea. Estuar. Coastal Shelf Sci. 54, 575-587. 

Martens, C.S., and Chanton, J.P. (1989) Radon as a tracer of biogenic gas equilibration and transport from methane-saturated sediments. J. Geophys. Res. 94, 3451-3459. 

The total organic carbon balance for lakes on the central Amazon floodplain can be examined by comparing total inputs due to primary production and external loading with total losses (Table 14.4). The combined input of organic carbon due to primary production, river import and local runoff was estimated at 117.3 Tg C yr. Combined losses due to biogenic gas emission and... 

With natural gas being a mixture of such structurally simple compounds, options available for correlation purposes are limited. Gas chromatography provides an indication of the distribution of the components present in the namral gas sample from which the ratio of methane/C2+ fraction can be determined. This is measure of the wetness of the gas and in certain cases can provide a measure of the maturity of the gas. The ratio needs to be combined with carbon and isotope ratio data to obtain the most useful information. A gas can be dominated by methane and, from the chromatogram alone, it is impossible to determine whether this is biogenic gas or a high maturity gas. As a result of thousands of... 

One of the drawbacks of using this technique is the need to freeze the canned samples if they cannot be analysed within one or two weeks of their collection. Failure to follow this procedure can create problems because of the generation of biogenic gas in the cans or the bacterial oxidation of the hydrocarbon gases to carbon dioxide. 

The presence of butanes in the sniffer data clearly separates the southern gas-producing trend from the area to the north of Block A-252. The grids over both Block A-152 and Block A-198 and the profile data north of Block A-252 exhibit a clear lack of propane and butane anomalies. The presence of mainly methane in the northern area suggests that these anomalies are derived from biogenic gas sources. 

SHALLOW BIOGENIC GAS COALHEU CAS THERMAL CAS OVER MATURED GAS... 

Mechalas, B.J., 1974. Pathways and environmental requirements for biogenic gas production in the ocean. In I.R. Kaplan (Editor), Natural Gases in Marine Sediments. Plenum, New York, NY, pp. 11—25. 

Adams, D. F., S. O. Farwell, M. R. Pack and E. Robinson (1981b). Biogenic gas emissions from soils in Eastern and Southeastern United States. J. Air Pollut. Control Assoc. 31, 1083-1089. 

The methane carbon isotopic compositions of Magnolia free and associated gases are invariably significantly lighter than that predicted from a simple maturity sequence. This is discussed below in the context of biogenic gas. 

Phase fractionation is responsible for development of the saturated gas-condensates at Magnolia and has resulted from the mixture of biogenic methane and thermogenic fluids. The relatively low pressure reservoirs that contain a large biogenic gas component are saturated. Fractionation in these cases probably occurred in situ, as undersaturated thermogenic fluids mixed with previously-emplaced biogenic gas (of unknown but probably low saturations). Two phase systems formed when, as a result, saturation pressures exceeded reservoir pressures. 

Edman, J. D., Jameson, E. W., Perkins, T. M. Guthrie, G. E. 2001. Mississippi Canyon 348 some reservoir engineering considerations regarding development of a deepwater biogenic gas accumulation. Society of Petroleum Engineers, Paper No. 71611. 

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