classification of huminite iccp system 1994 abstract in the new classification iccp system 1994 the maceral group huminite has been revised from the previous classification iccp 1971 int handbook coal petr suppl to 2nd ed to accommodate the nomenclature to changes in the other maceral groups especially the changes in the vitrinite classification iccp 1998 the new vitrinite classification iccp system 1994 fuel 77 349 358 the vitrinite and huminite systems have been correlated so that down to the level of sub maceral groups the two systems can be used in parallel at the level of macerals and for finer classifications the analyst now has according to the nature of the coal and the purpose of the analysis a choice of using either of the two classification systems for huminite and vitrinite this is in accordance with the new iso coal classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals

the pre quaternary history of fire abstract although evidence for land vegetation comes from the silurian and maybe even earlier the first record of fossil charcoal fusain is from the late devonian for this period there are only one or two isolated records not until the early carboniferous is there a record of extensive charcoal deposits mainly preserved in near shore clastic sediments which provide evidence of significant and widespread wildfires by the late carboniferous charcoal was common or abundant in a wide range of facies including tropical wetland peats wildfire played an important role in shaping the environment at this time the latest palaeozoic and early mesozoic records of charcoal are fewer whereas important deposits of late mesozoic age are found worldwide the occurrence of charcoal at the cretaceous tertiary boundary has been highlighted as evidence for a global fire following a meteorite impact but this interpretation is questionable charcoal has been widely reported from tertiary sediments and its appearance in the quaternary and recent is not solely as a result of human impact through the past 400 million years there have been major changes in atmospheric oxygen levels that affected fire intensity and frequency fire systems thus have a long history and their impact on shaping the environment is assessed

radium isotopes in the chesapeake bay 228ra and 226ra are enriched in waters of chesapeake bay through fluxes from the bottom sediments and desorption from particles entering the estuary the activity ratio of 228ra 226ra increases from 1 5 in the susquehanna river to 3 4 in waters of 15 20 salinity apparently much of the 228ra is supplied by diffusion from sediments within the bay while desorption from particles entering the bay is more important for 226ra because of the multiple inputs and long residence time of water in the bay no curvature is obvious in a plot of radium isotope concentration vs salinity

origin of minerals in joint and cleat systems of the pottsville formation black warrior basin alabama implications for coalbed methane generation and production coalbed methane is produced from naturally fractured strata in the lower pennsylvanian pottsville formation in the eastern part of the black warrior basin alabama major fracture systems include orthogonal fractures which consist of systematic joints in siliciclastic strata and face cleats in coal that strike northeast throughout the basin calcite and minor amounts of pyrite commonly fill joints in sandstone and shale and less commonly cleats in coal joint fill calcite postdates most pyrite and is a weakly ferroan coarse crystalline variety that formed during a period of uplift and erosion late in the burial history pyrite forms fine to coarse euhedral crystals that line joint walls or are complexly intergrown with calcite stable isotope data reveal large variations in the carbon isotope composition of joint and cleat fill calcite 10 3 to 24 3 peedee belemnite pdb but only a relatively narrow range in the oxygen isotope composition of this calcite 16 2 to 4 1 pdb negative carbon values can be attributed to 13c depleted co2 derived from the oxidation of organic matter and moderately to highly positive carbon values can be attributed to bacterial methanogenesis assuming crystallization temperatures of 2050c most joint and cleat fill calcite precipitated from fluids with 18o ratios ranging from about 11 to 2 standard mean ocean water smow uplift and unroofing since the mesozoic led to meteoric recharge of pottsville strata and development of freshwater plumes that were fed by meteoric recharge along the structurally upturned southeastern margin of the basin influxes of fresh water into the basin via faults and coalbeds facilitated late stage bacterial methanogenesis which accounts for the high gas content in coal and the carbonate cementation of joints and cleats diagenetic and epigenetic minerals can affect the transmissivity and storage capacity of joints and cleats and they appear to contribute significantly to interwell heterogeneity in the pottsville formation in highly productive coalbed methane fields joint and cleat fill calcite have strongly positive 13c values whereas calcite fill has lower 13c values in fields that are shut in or abandoned petrographic analysis and stable isotope geochemistry of joint and cleat fill cements provide insight into coalbed methane reservoir quality and the nature and extent of reservoir compartmentalization which are important factors governing methane production

bioassay for estimating the biogenic methane generating potential of coal samples abstract generation of secondary biogenic methane in coal beds is likely controlled by a combination of factors such as the bioavailability of coal carbon the presence of a microbial community to convert coal carbon to methane and an environment supporting microbial growth and methanogenesis a set of treatments and controls was developed to bioassay the bioavailability of coal for conversion to methane under defined laboratory conditions treatments included adding a well characterized consortium of bacteria and methanogens enriched from modern wetland sediments and providing conditions to support endemic microbial activity the contribution of desorbed methane in the bioassays was determined in treatments with bromoethane sulfonic acid an inhibitor of microbial methanogenesis the bioassay compared 16 subbituminous coal samples collected from beds in texas tx wyoming wy and alaska ak and two bituminous coal samples from pennsylvania pa new biogenic methane was observed in several samples of subbituminous coal with the microbial consortium added but endemic activity was less commonly observed the highest methane generation 80 mol methane g coal 56 scf ton or 1 75 cm 3 g was from a south tx coal sample that was collected from a non gas producing well subbituminous coals from the powder river basin wy and north slope borough ak contained more sorbed original methane than the tx coal sample and generated 0 23 mol g up to 16 scf ton or 0 5 cm 3 g new biogenic methane in the bioassay standard indicators of thermal maturity such as burial depth nitrogen content and calorific value did not explain differences in biogenic methane among subbituminous coal samples no original methane was observed in two bituminous samples from pa nor was any new methane generated in bioassays of these samples the bioassay offers a new tool for assessing the potential of coal for biogenic methane generation and provides a platform for studying the mechanisms involved in this economically important activity

development of web based organic petrology photomicrograph atlases and internet resources for professionals and students abstract with advances in web applications organic petrography and other related disciplines are in need of updated online resources and educational tools to aid professionals and students in the identification and interpretation of macerals the u s geological survey usgs organic petrology laboratory along with usgs eastern energy resources science center information technology staff have developed five web atlases containing images of organic matter in geologic materials 1 an american society for testing and materials astm atlas 2 an organic petrology taxonomy for international classification optic of coal macerals atlas 3 an interactive gulf coast photomicrograph web atlas i map 4 an organic material in shales atlas shale and 5 an interactive blue white ultraviolet uv light atlas light each web atlas contains images of macerals with associated sample and petrographic data collected by the usgs these webpages will provide means to preserve and circulate petrographic data collected by the usgs for coal and shale samples from all over the world

the genesis of coal from the viewpoint of coal petrology abstract the genesis of the microscopic constituents of coal macerals and of maceral associations microlithotypes representing various coal facies is discussed in the light of recent advances that have been made in the study of coals and modern peats peat microscopy especially promoted the understanding of humification and biological gelification both of which are decisive for the genesis of huminites vitrinites in brown coals and hard coals respectively microbial activity during peatification has been documented by chemists microbiologists and petrologists and recently by electron microscopical observations in coals this activity leads to the incorporation of lipid substances into the humic matter and later influences the chemical physical and technological properties of vitrinites geochemical gelification transforms the huminites of brown coals into the vitrinites of bituminous coals and is probably caused by the onset of bitumen generation in coal in this process the hydrogel brown coal is transformed to the bitumogel bituminous coal coal as a source rock for oil has become an important research subject for coal petrologists and oil exploration the formation of more or less liquid bitumen and its later cracking to gaseous hydrocarbons leads to the coalification jumps of the macerals especially liptinites and vitrinites and to the generation of secondary macerals like exsudatinite bitumen and micrinite dead carbon bituminization in coal has been revealed by the use of fluorescence microscopy which also found the presence of new liptinite macerals bituminite fluorinite and exsudatinite and suggests a higher proportion of algal material in coals than was thought earlier the genesis of various types of inertinite macerals will probably become an increasingly important subject of research especially with regard to rank inertinites that seem to attain their high inertinitic reflectance initially during coalification besides the origin of macerals the origin of various coal facies in terms of maceral associations is considered in relation to the palaeogeographic depositional milieu the peat forming vegetation palaeoclimate water and nutrient supply acidity marine and calcareous influence and fire with examples from euramerican carboniferous coals gondwana coals and tertiary brown coals vegetation water and oxygen supply eh conditions are most important for the generation of coal facies vegetation has been reconstructed with the help of palaeobotany including palynology cuticular analysis and wood anatomy in brown coals and with the study of petrified permineralized peats preserved in coal balls the microscopical investigations of botanically recognizable plant remains isolated from coals or accompanying rocks has been especially informative however the results of palynological and cuticular analyses should be evaluated with caution considering the varying resistance of palynomorphs and cuticles and in the case of palynomorphs their possible extrapaludal origin microscopical studies of modern peats that were derived from different types of vegetation growing in different hydrological environments have been very helpful in interpreting coal facies especially in brown coals the much disputed origin of brown coal lithotypes is considered in detail for hard coals there seems to be agreement that coal layers rich in vitrites and liptinite poor clarite were deposited in wet forest swamps that microlayered liptinite rich clarites are sub aquatic humic muds and that inertinite rich durites represent oxidized peats the origin of liptinite rich durites is controversial either subaquatic muds or oxidized peats the latter perhaps from raised bogs a recent trend in the literature is the assumption that many if not all mineable coal seams have been deposited in raised bogs under ombrogenous oligotrophic conditions although raised bogs with a dense arborescent vegetation are known from borneo it seems not probable that most seams which were deposited in foredeeps or steadily sinking graben zones are of ombrogenous origin although a succession from relatively wet and eutrophic to relatively dry and oligotrophic conditions may be true for occasional seams but as in modern peats striking changes of coal facies are commonly caused by hydrological events e g inundations as a consequences of crevasses or of fires that burned the peat the origin of the inertinite rich gondwana coals is discussed in relation to their specific climatic conditions and a comparison with sub arctic peats is recommended coals influenced by marine and calcareous conditions are characterized by high contents of sulfur and pyrite as well as by hydrogen rich vitrinites with a relatively low reflectance and high fluorescence all due to a strong bacterial activity in peats of low acidity proposals for further research are made in the conclusions

coupled hydrology and biogeochemistry of paleocene eocene coal beds northern gulf of mexico thirty six formation waters gas and microbial samples were collected and analyzed from natural gas and oil wells producing from the paleocene to eocene wilcox group coal beds and adjacent sandstones in north central louisiana usa to investigate the role hydrology plays on the generation and distribution of microbial methane major ion chemistry and cl br relations of wilcox group formation waters suggest mixing of freshwater with halite derived brines high alkalinities up to 47 8 meq l no detectable so4 and elevated 13c values of dissolved inorganic carbon up to 20 5 vienna peedee belemnite vpdb and co2 up to 17 67 vpdb in the wilcox group coals and adjacent sandstones indicate the dominance of microbial methanogenesis the 13c and d values of ch4 and carbon isotope fractionation of co2 and ch4 suggest co2 reduction is the major methanogenic pathway geochemical indicators for methanogenesis drop off significantly at chloride concentrations above 1 7 mol l suggesting that high salinities inhibit microbial activity at depths greater than 1 6 km formation waters in the wilcox group contain up to 1 6 modern carbon a14c to at least 1690 m depth the covariance of d values of co produced h2o and ch4 indicate that the microbial methane was generated in situ with these late pleistocene or younger waters the most enriched carbon isotope values for dissolved inorganic carbon dic and co2 and highest alkalinities were detected in wilcox group sandstone reservoirs that were co2 flooded in the 1980s for enhanced oil recovery leading to the intriguing hypothesis that co2 sequestration may actually enhance methanogenesis in organic rich formations

organic petrology and coalbed gas content wilcox group paleocene eocene northern louisiana abstract wilcox group paleocene eocene coal and carbonaceous shale samples collected from four coalbed methane test wells in northern louisiana were characterized through an integrated analytical program organic petrographic analyses gas desorption and adsorption isotherm measurements and proximate ultimate analyses were conducted to provide insight into conditions of peat deposition and the relationships between coal composition rank and coalbed gas storage characteristics the results of petrographic analyses indicate that woody precursor materials were more abundant in stratigraphically higher coal zones in one of the cbm wells consistent with progradation of a deltaic depositional system holly springs delta complex into the gulf of mexico during the paleocene eocene comparison of petrographic analyses with gas desorption measurements suggests that there is not a direct relationship between coal type sensu maceral composition and coalbed gas storage moisture as a function of coal rank lignite subbituminous a exhibits an inverse relationship with measured gas content this result may be due to higher moisture content competing for adsorption space with coalbed gas in shallower lower rank samples shallower 600 m coal samples containing less moisture range from under to oversaturated with respect to their ch4 adsorption capacity

organic geochemistry and petrology of subsurface paleocene eocene wilcox and claiborne group coal beds zavala county maverick basin texas usa abstract coal samples from a coalbed methane exploration well in northern zavala county maverick basin texas were characterized through an integrated analytical program the well was drilled in february 2006 and shut in after coal core desorption indicated negligible gas content cuttings samples from two levels in the eocene claiborne group were evaluated by way of petrographic techniques and rock eval pyrolysis core samples from the paleocene eocene indio formation wilcox group were characterized via proximate ultimate analysis in addition to petrography and pyrolysis two indio formation coal samples were selected for detailed evaluation via gas chromatography and fourier transform infrared ftir and 13c cpmas nmr spectroscopy samples are subbituminous rank as determined from multiple thermal maturity parameters elevated rank relative to similar age coal beds elsewhere in the gulf coast basin in the study area is interpreted to be a result of stratigraphic and or structural thickening related to laramide compression and construction of the sierra madre oriental to the southwest vitrinite reflectance data along with extant data suggest the presence of an erosional unconformity or change in regional heat flow between the cretaceous and tertiary sections and erosion of up to 5 km over the cretaceous the presence of liptinite rich coals in the claiborne at the well site may indicate moderately persistent or recurring coal forming paleoenvironments interpreted as perennially submerged peat in shallow ephemeral lakes with herbaceous and or flotant vegetation however significant continuity of individual eocene coal beds in the subsurface is not suggested indio formation coal samples contain abundant telovitrinite interpreted to be preserved from arborescent above ground woody vegetation that developed during the middle portion of mire development in forested swamps other petrographic criteria suggest enhanced biological chemical and physical degradation at the beginning and end of indio mire development fluorescence spectra of sporinite and resinite are consistent and distinctly different from each other attributed to the presence of a greater proportion of complex asphaltene and polar molecules in resinite gas chromatography of resinite rich coal shows sesquiterpenoid and diterpenoid peaks in the c14 17 range which are not present in resinite poor coal quantities of extracts suggest bitumen concentration below the threshold for effective source rocks 30 50 mg hydrocarbon g total organic carbon hc g toc saturate aromatic and pristane phytane pr ph ratios are different from values for nearby tertiary reservoired crude oil suggesting that the indio coals are too immature to source liquid hydrocarbons in the area however moderately high hi values 200 400 mg hc g rock may suggest some potential for naphthenic paraffinic oil generation where buried more deeply down stratigraphic structural dip extractable phenols and c20 alkanes are suggested as possible intermediates for acetate fermentation in microbial methanogenesis which may however be limited by poor nutrient supply related to low rainfall and meteoric recharge rate or high local sulfate concentration

geological controls on gas content distribution of coal seams in the kinik coalfield soma basin turkey abstract the miocene soma coal basin may be one of the most promising areas for low rank coalbed methane in turkey so far the coalbed methane potential of the coal seams in the kinik coalfield soma basin has not been adequately studied a systematic investigation was performed on the gas content distribution of the kp1 and km2 coal seams and its geological controls which has been based on the geological data and the experimental results of 84 coal samples taken from 37 coal exploration wells in the kinik coalfield soma basin samples were analyzed in terms of coal properties and gas content the gas content was measured by the direct method based on the canister desorption test the gas content of the kp1 and km2 coal seams range from 0 90 to 2 61 m3 t and 0 51 to 3 86 m3 t respectively on as received basis with increasing trend from west to east areas in both seams diffusivity values of the kp1 and km2 coal seams vary from 2 84 10 5 min 1 to 56 4 10 5 min 1 and from 0 64 10 5 min 1 to 54 3 10 5 min 1 respectively the gas content of the kp1 seam has not been correlated with the coal properties whereas the gas content of the km2 seam has positive correlation with fixed carbon content and gross calorific value and negative correlation with moisture and ash content normal faults are well developed in the study area play an important role at gas migration causing gas dissipation and reduced gas content of each coal seam in the northern part the low gas content may result from the combined effects of the geological structure thickness of overlying unit burial depth and coal thickness in the southern part the gas content of coal seams is controlled by the combined effects of relatively favorable factors including fewer normal faults thicker overlying unit high burial depth and thick coal seam the variation of the gas content for the coal seams is a comprehensive reflection of geological factors with each coal seam has its own pattern of gas distribution and this should be considered for the future coalbed methane exploration and development studies in soma basin

radium isotopes in the orinoco estuary and eastern caribbean sea radium isotopes provide a means of identifying the source of freshened waters in the ocean and determining the time elapsed since these waters were in the estuary we present evidence that during april waters from the amazon mixing zone pass within 50 km of the mouth of the orinoco river these amazon waters are characterized by a lower 228ra 226ra activity ratio ar than are waters from the orinoco at similar salinities during autumn the increased discharge of the orinoco displaces the freshened amazon waters seaward yet the two can be distinguished clearly within the caribbean sea waters of orinoco origin carry a characteristic radium signature including excess activities of 224ra this isotope may be used to estimate the time elapsed since the waters were removed from contact with sediments current speeds based on 224ra dating ranged from 15 to 33 cm s during april the radium isotopes also provide an assessment of sediment mixing in the estuary during low discharge april considerable mixing of older sediment by physical or biological processes or dredging maintained high activities of 228ra in the estuary and produced the highest 228ra 226ra ar s yet measured in any estuary during high discharge september a large fraction of the 228ra was derived from desorption from fresh sediment rather than mixing of older sediments activities of 224ra were high in the estuary during both high and low discharge indicating that considerable mixing of recently introduced sediment must occur during each period the high 224ra 228ra ar s measured in september imply that the same sediments were being resuspended during high discharge and that there was little exposure of older sediments which had been stored in the estuary for months to years during april 224ra and 228ra activities in the water were about equal indicating that most of the sediment being resuspended had been stored in the estuary long enough to reestablish radioactive equilibrium in the 232th decay series i e 20 years

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

carboniferous coals of the zonguldak basin northwest turkey implications for coalbed methane potential we investigated the carboniferous coals in the zonguldak basin northwest turkey using a multidisciplinary approach including petrographical and geochemical analyses gas adsorption and gas content measurements artificial maturation experiments on selected coals and one dimensional 1 d modeling of the basin evolution and hydrocarbon generation the main emphasis was set on the definition of coalbed methane cbm generation capability and adsorption capacity of the coals considering these properties of coals and the amount and composition of gas within the coal seams we carried out a comprehensive evaluation of the cbm potential of the basin three areas in the basin namely armutcuk zonguldak and amasra were investigated separately for their cbm potential from the standpoint of petroleum oil and or gas generation the coals in the armutcuk and amasra areas are located within the oil generation window the coals of the zonguldak area are located within the oil and gas generation window computer aided basin modeling using a basin specific kinetic data set of hydrocarbon generation from coals suggests that significant quantities of gas have been generated only in the zonguldak area modeling results also indicate that major gas generation from the base of the westphalian a kozlu formation in the zonguldak area occurred between 80 and 42 ma during the late cretaceous early eocene prior to basin inversion that started at 42 ma and continues at present the predicted amount of generated coalbed gas from coal seams in the gas generation zone is several times higher than the adsorption capacity of the respective seams a certain amount of this gas controlled by the adsorption capacity is stored within the coal seams where it is generated gas generated in excess of storage capacity obviously would have been expelled from the coal part of the expelled gas is accumulated in coal seams located above the gas generation zone however the coal seams within and above the gas generation zone are undersaturated with respect to their adsorption capacity the undersaturation is probably caused by remigration of gas that is desorbed because of pressure decrease during basin inversion of more than 2500 m 8203 ft over the last 42 m y the rest of the gas generated within the coal seams and expelled first because of the overflow of adsorption capacity and then because of the desorption during basin inversion has either migrated to source conventional gas reservoirs or has been lost to the surface during basin inversion because the basin has not been explored for conventional gas reservoirs a conclusive mass balance cannot yet be performed despite basin inversion and remigration of gas some coal seams still contain gas amounts of up to 10 cm 3 g of coal indicating a cbm potential

geochronology and stratigraphy of late pleistocene lake cycles on the southern bolivian altiplano implications for causes of tropical climate change large paleolakes 33 000 60 000 km2 that once occupied the high altitude poopo coipasa and uyuni basins in southern bolivia 18 22 s provide evidence of major changes in low latitude moisture in these now dry or oligosaline basins extensive natural exposure reveals evidence for two deep lake and several minor lake cycles over the past 120 k y fifty three new u th and 87 new 14c dates provide a chronologic framework for changes in lake level deposits from the ouki deep lake cycle are extensively exposed in the poopo basin but no deep lakes are apparent in the record between 98 and 18 1 ka the ouki lake cycle was 80 m deep and nineteen u th dates place this deep lake cycle between 120 and 98 ka shallow lakes were present in the terminal uyuni basin between 95 and 80 ka salinas lake cycle at ca 46 inca huasi lake cycle and between 24 and 20 5 ka sajsi lake cycle the tauca deep lake cycle occurred between 18 1 and 14 1 ka resulting in the deepest 140 m and largest lake in the basin over the past 120 ka multiple 14c and u th dates constrain the highest stand of lake tauca along a topographically conspicuous shoreline between 16 4 and 14 1 ka a probable post tauca lake cycle the coipasa produced a 55 m deep lake that is tentatively dated between 13 and 11 ka we suggest that paleolakes on the bolivian altiplano expanded in response to increased moisture in the amazon and enhanced transport of that moisture onto the altiplano by strengthened trade winds or southward displacement of the intertropical convergence zone itcz pole to equator sea surface temperature sst and atmospheric gradients may have influenced the position of the itcz affecting moisture balance over the altiplano and at other locations in the amazon basin links between the position of the itcz and the ca 23 ka precessional solar cycle have been postulated march insolation over the altiplano is a relatively good fit to our lake record but no single season or latitude of solar cycling has yet to emerge as the primary driver of climate over the entire amazon basin temperature may influence altiplano lake levels indirectly as potentially dry glacial periods in the amazon basin are linked to dry conditions on the altiplano intensification of the trade winds associated with la nina like conditions currently brings increased precipitation on the altiplano and deep lake development during the tauca lake cycle coincided with apparently intense and persistent la nina like conditions in the central pacific this suggests that sst gradients in the pacific are also a major influence on deep lake development on the altiplano

fate of injected co2 in the wilcox group louisiana gulf coast basin chemical and isotopic tracers of microbial brine rock co2 interactions the 2800 sandstone of the olla oil field is an oil and gas producing reservoir in a coal bearing interval of the paleocene eocene wilcox group in north central louisiana usa in the 1980s this producing unit was flooded with co2 in an enhanced oil recovery eor project leaving 30 of the injected co2 in the 2800 sandstone post injection this study utilizes isotopic and geochemical tracers from co produced natural gas oil and brine to determine the fate of the injected co2 including the possibility of enhanced microbial conversion of co2 to ch4 via methanogenesis stable carbon isotopes of co2 ch4 and dic together with mol co2 show that 4 out of 17 wells sampled in the 2800 sandstone are still producing injected co2 the dominant fate of the injected co2 appears to be dissolution in formation fluids and gas phase trapping there is some isotopic and geochemical evidence for enhanced microbial methanogenesis in 2 samples however the co2 spread unevenly throughout the reservoir and thus cannot explain the elevated indicators for methanogenesis observed across the entire field vertical migration out of the target 2800 sandstone reservoir is also apparent in 3 samples located stratigraphically above the target sand reservoirs comparable to the 2800 sandstone located along a 90 km transect were also sampled to investigate regional trends in gas composition brine chemistry and microbial activity microbial methane likely sourced from biodegradation of organic substrates within the formation was found in all oil fields sampled while indicators of methanogenesis e g high alkalinity 13c co2 and 13c dic values and oxidation of propane were greatest in the olla field likely due to its more ideal environmental conditions i e suitable range of ph temperature salinity sulfate and iron concentrations

heat flow in the gulf coastal plain forty four new heat flow values from panhandle florida southwestern georgia southern alabama mississippi and louisiana range from 13 mw m sup 2 0 3 hfu 1 hfu 1 mu cal cm sup 2 s sup 1 41 8 mw m sup 2 in florida and alabama to 88 mw m sup 2 2 1 hfu in northern louisiana in general the values depict the eastern gulf coastal plain as an area with low to normal continental heat flow that increases from east to west anomalously low heat flow 13 33 mw m sup 2 0 3 0 8 hfu characterizes northcentral florida southwestern georgia and southern alabama while in northern louisiana 13 measurement sites yield values ranging from 50 mw m sup 2 1 2 hfu to 88 mw m sup 2 2 1 hfu distinctive disruptions in the temperature depth profiles attributed to convective effects within aquifers are limited in magnitude and extent and do not alter the geothermal gradient computations the region of relatively high heat flux in northern louisiana is coincident with an area underlain by cenozoic alkalic igneous rocks of the monroe uplift and an abnormal concentration of radiogenic heat sources within that body is postulated as the cause of the thermal anomaly

organic geochemical and petrographic characteristics of tertiary coals in the northwest sarawak malaysia implications for palaeoenvironmental conditions and hydrocarbon generation potential abstract tertiary coals from mukah and balingian coalfields in the northwest sarawak malaysia were investigated to evaluate their regional rank variation petroleum generative potential and to reconstruct the palaeoenvironment conditions during peat accumulation the tertiary coals are characterized by high total organic carbon contents toc and yield of bitumen extraction ranging from 31 3 to 55 9 wt and 25 724 9 92 143 7 ppm respectively meet the standard as a good source rock potential the mukah and balingian coals were generally plotted in an area of type iii kerogen and mixed type ii iii kerogens with hi values between 90 and 289 mg hc g toc whereby the coals were derived from plant materials of terrigenous origin this shows that the balingian coals are dominated by type iii terrigenous kerogen while mukah coals are dominated by type ii iii kerogens and are thus considered to be generate mainly gas prone and limited oil prone this is also supported by macerals composition and open system pyrolysis gas chromatography py gc the mukah and balingian coals are thermally immature in rang from lignite to sub bituminous c rank possessing huminite reflectance in the range of 0 26 0 39 this immaturity has a considerable influence on the proximate analysis particularly on relatively high moisture and volatile matter contents and relatively low fixed carbon content petrographically it was observed that the mukah and balingian coals are dominated by huminite with low to high amounts of liptinite and relatively low amounts of inertinite pointing to predominantly anaerobic deposition conditions in the paleomires with limited thermal and oxidative tissue destruction the palaeoenvironment conditions of the coals are generally interpreted as a lower deltaic plain wet peat swamp depositional setting which are generally characterised by low tpi and high gi values and are plotted on the marsh field of the diessel s diagram this is usually consistent with generate relatively high ash yield as is the case of the mukah and balingian coals

relationship between petrographic and chemical properties and coal seam geometry hance seam breathitt formation southeastern kentucky the upper hance coal seam in southeastern kentucy was used as a template to examine the spatial distribution of ash yield sulfur content and petrographic constituents relative to the geometry of the deposit geometric characteristics include thinning and splitting of the two main benches leaders and riders analytical data showed the thick non split portions of the coal body to be low in ash and sulfur as well as vitrinite content whereas the thinned and split margins were higher in ash sulfur and vitrinite content these relationships suggest that thick non split portions of the upper hance peat accumulated in areas isolated from detrital influx while thinner marginal peat was subject to intermittent flooding from adjacent channels marginal peat was derived from larger trees which flourished at the mire s edge in the presence of adequate nutrients whereas only stunted vegetation subsisting in the nutrient depleted center contributed to interior peat accumulation ponds formed on the sparsely vegetated mature surface of the bog s interior the petrographic and chemical character of the hance coal body is analogous to ombrogenous domed peats which characteristically contain higher concentrations of inorganics at the periphery of the deposit

pore characteristics of wilcox group coal u s gulf coast region implications for the occurrence of coalbed gas abstract pore characteristics of 27 subbituminous coal samples 16 mesh splits from the paleocene eocene wilcox group of north louisiana ouachita and caldwell parishes and south texas zavala county were examined in relation to desorbed gas content coal gas of the wilcox group is primarily biogenic in origin thermogenic gas also may be present in some areas on an as received basis desorbed gas contents range from 0 59 to 1 28 m 3 t for ouachita parish samples 0 37 to 5 19 m 3 t for the caldwell parish samples and 0 02 to 0 06 m 3 t for the zavala county samples for louisiana coal samples micropore surface area and volume are correlated to the desorbed gas content of the wilcox group coal correlations r 0 50 and 0 47 respectively suggesting that micropore surface area and volume are important in terms of gas holding capacity adsorption by micropores appears to be the primary form of gas storage for the louisiana coal samples micropore surface area and volumes also are strongly correlated with the carbon ash yield ratio r 0 97 and 0 94 respectively indicating that gas sorption occurs primarily on organic matter mineral matter appears to reduce the sorption capacity of the coal micropore width decreases with depth r 0 63 probably as the result of increasing pressure and coal rank with depth for the louisiana coal samples mesopore surface area is negatively correlated with the carbon ash yield ratio r 0 70 suggesting that mesopores are preferentially associated with mineral matter average mesopore size is correlated with desorbed gas r 0 80 for the relatively shallow ouachita parish samples average depth 441 m 1446 ft these results suggest that the permeability of the wilcox coal is greater in the shallow stratigraphic intervals compared to deeper intervals additionally mesopore size decreases with depth r 0 80 for ouachita parish coal samples negative correlations of gas with mesopore surface area r 0 74 and mesopore volume r 0 56 strongly suggest that gas is not adsorbed in mesopores and that free gas may be present in larger mesopores macropores or fractures of the wilcox coal results also suggest that moisture in ouachita parish samples is present in mesopores moisture in mesopores may have blocked gas adsorption the low gas south texas samples average depth 313 m 1026 ft are markedly different from the louisiana samples specifically micropore surface area and micropore volume are negatively correlated with desorbed gas for the texas samples r 0 21 and 0 36 respectively geologic or environmental conditions probably were not conducive to the generation or storage of microbial gas in the zavala county coals the geologic settings i e salinity of formation water groundwater recharge permeability of coal of each study area are important factors that need to be considered in relation to the potential for generation or storage of microbial gas in south texas tectonic stress may have led to a reduction in permeability in the wilcox group coal creating an unfavorable environment for the generation or preservation of microbial gas the subbituminous rank of the zavala coals is also too low for significant thermogenic gas generation to have occurred

variation in permeability with lithotype and maceral composition of cretaceous coals of the canadian cordillera abstract the permeability of high and medium volatile bituminous cretaceous coal at the megascopic and microscopic scale is investigated utilizing a pressure decay permeameter the order of decreasing permeability with lithotype is bright average 4 1 md banded 0 79 md fibrous 0 50 md banded dull 0 14 md and dull 0 016 md bright coals are the most permeable because of associated macro fracturing cleat banded dull coal permeability generally increases with increasing vitrinite content the lowest permeabilities occur in dull coals with a high mineral and inertinite content fibrous coal has a higher permeability than dull coal of the same rank due to the abundance of macroporous fusinite in fibrous coal dull coal permeability decreases with an increase in rank but these results are overshadowed by compositional variability between samples pressure decay measurements are more reliable for dull lithotypes as these lithotypes do not fracture as easily during sample preparation although measured permeabilities are optimistic due to the relaxation of stress upon exposure of coal to atmospheric pressure the results obtained are representative of the range of permeabilities of coal lithotypes and provide insight into the variability in permeability that may exist at high effective stress in the subsurface

controls on methane sorption capacity of indian coals details of methane sorption properties of some indian coals ranging in rank from high volatile bituminous c 0 62 ro max to medium volatile bituminous coal 1 46 ro max were investigated to determine the major factors influencing gas adsorption capacity and desorption rate variables studied included moisture content mineral matter content rank and coal type maceral composition adsorption isotherm analysis of dry coals showed that adsorption capacity followed a second order polynomial trend with rank equilibrium moist samples showed a linear increase in adsorption capacity with rank and had a significantly reduced adsorption capacity compared to the dry coals with the reduction being related to the moisture content mineral matter acted as a simple diluent to the gas adsorption capacity of the coals and was found to be nonadsorbent adsorption capacity moist was reduced by 0 32 cm3 g 10 ft3 gas t for every 1 increase in the ash yield bright and dull coal lithotypes showed strong separation in their adsorption capacities on an as analyzed basis with the bright coals adsorbing greater quantities of gas on a dmmf basis however no relationship was observed between coal type and gas storage capacity comparison of maceral composition with adsorption capacity dry confirmed this observation effective diffusivity de of methane through the coal was seen to be affected by coal type and rank effective diffusivity de decreased as rank increased which is related to the increasing microporous nature of the coal bulk coals tested had 2 3 times larger effective diffusivities than bright coals and dull coals had intermediate rates the larger de values for the bulk coals may be related to the presence of collodetrinite coupled with mineral matter which acts as higher permeability pathways for the gas compared with the high ash dull coals dominated by inertinite macerals differences were noted with similar age permian australian coals where methane adsorption capacities were larger and coal type had a stronger influence on adsorption capacity begin page 202

influence of lamprophyre sills on coal metamorphism coalbed gas composition and coalbed gas occurrence in the tongxin minefield datong coalfield china abstract magmatic intrusions in coal bearing strata can significantly change the physical and chemical properties of the intruded coal lamprophyre intrusions are extensive in coal seams 3 5 and 8 of the carboniferous permian coal bearing strata in the southeastern and southwestern regions of the tongxin minefield datong coalfield china they appear primarily as sills of varying magnitudes with thicknesses ranging from 0 15 to 23 51 m in this area coals can be classified as unaffected normal geothermal gradient and intrusion affected unaffected coals are of high volatile bituminous rank with values of maximum vitrinite reflectance ranging from 0 7 to 0 9 whereas intrusion affected coals have values of maximum vitrinite reflectance ranging from 0 9 to 7 2 a marked decrease in the degree of coalification can be observed with increasing distance from the lamprophyre intrusions near the intrusion coal contacts high volatile bituminous coals have been thermally altered to form natural coke the carbonate contents in intrusion affected coals 0 2 46 1 are significantly higher than those of the unaffected coal 0 2 0 the coalbed gases of coal seams 3 5 and 8 are highly variable in both their molecular compositions and overall gas contents their co2 volumes vary from 0 01 to 6 55 m3 t daf higher co2 values are found in the coals affected by intrusions and roughly decrease with increasing distance from the lamprophyre igneous intrusions toward the central region of the minefield these variations in gas compositions are mainly related to magmatic activity the coalbed gas contents in coal seams 3 5 and 8 range from 1 48 to 16 43 m3 t on a dry ash free basis the positive correlation observed between gas content and the ratio of co2 ch4 co2 occurs only in intrusion affected coals lamprophyre intrusions have negative effects on ch4 content in the study area since co2 has a higher adsorption capacity than ch4 c2h6 and n2 the injection of gaseous co2 derived from magmatic intrusions can effectively displace ch4 rich reservoir gas in addition there is a positive correlation between ash content and gas content on a dry ash free basis ash content is positively correlated with the ratio of co2 ch4 co2 occurring only in intrusion affected coals massive secondary carbonates that filled in the cleats act as small scale impermeable seals which provide a sealing effect both on gas contents and gas compositions during uplift

the producibility of coalbed methane from wilcox coals in louisiana abstract the producibility model for coalbed methane contains six controls they are 1 gas content 2 permeability 3 tectonic and structural setting 4 depositional setting 5 hydrology and 6 coal rank and gas generation gas content in central louisiana coalbed methane basin celcom coals was proven in 1989 when the torch operating company perforated the no 3 greer well sec 21 t14n r4e the well immediately began flowing gas 50 000 cfg d and 65 bbls water d the 3 greer flowed approximately 2 8 mmcfg over a three month period and was plugged permeability is indicated by the separation approximately 2 ohms of the 16 short normal and the 40 conductivity curves in most but not all e logs strongly developed spontaneous self potential sp in many e logs further indicates permeability tectonic and structural setting the celcom is situated between the sabine uplift and lasalle arch on the west southwest the d arbonne platform on the northwest and the monroe uplift on the northeast this location effected control on the wilcox depositional environments depositional setting the coals of the celcom were likely deposited on top of abandoned delta sequences prograding gulfward hydrology the coals of the celcom do not outcrop at the surface and therefore are not recharged with percolating ground water which must be removed during production the thick cane river shale section overlying the wilcox separates the brackish and fresh water sands of the sparta and cockfield from the saline waters of the wilcox the coals have been compacted through the burial process and the amount and type of contained water is not known although it is probably salt water coal rank and gas generation cores taken in equivalent sections in concordia parish louisiana reveal a vitrinite reflectance value of ro 0 45 a coal rank of bituminous

coalbed methane characteristics of gates formation coals northeastern british columbia effect of maceral composition the majority of research reported on methane adsorption characteristics of coal seams has focused on vitrinite rich coals however western canadian coals are more inertinite rich than those of the western united states and are shown to differ in gas adsorption characteristics the influence of maceral composition upon gas adsorption characteristics of medium volatile coal samples from the middle cretaceous gates formation of northeastern british columbia was investigated lithotype coal facies samples were analyzed for surface area maceral and mineral composition and methane adsorption standard coal analyses were also performed proximate low temperature ash and equilibrium moisture the vitrinite content of the samples analyzed ranges from 18 to 95 vol min ral matter free the ash yield varies from 4 4 to 33 7 wt both maceral composition and mineral matter content have an important influence on adsorption characteristics as indicated by carbon dioxide surface areas and methane adsorption isotherms on a mineral matter free basis the amount of methane adsorbed generally increases with vitrinite enrichment the lowest methane adsorption occurs in the sample with the highest inertinite content carbon dioxide surface areas of the lithotypes range from 87 to 176 m2 g on a raw coal basis and from 99 to 184 m2 g on a mineral matter free basis surface area generally decreases with increased mineral matter content and increases with increased vitrinite content the increase in adsorption of both methane and carbon dioxide with increased vitrinite concentration is interpreted a resulting from differences in the pore size distribution of vitrinite and inertinite vitrinite is predominantly microporous whereas inertinite is meso to macroporous the monolayer volumes of carbon dioxide as calculated from the dubininradushkevich equation are higher than those of methane as determined from the langmuir equation but are correlated the methane adsorption isotherms and surface area data indicate that the maceral compositional variations in coal are at least as significant as coal rank in determining the potential volume of adsorbed methane and thus the coalbed methane potential of a deposit

the characteristics of coal reservoir pores and coal facies in liulin district hedong coal field of china the composition rank coal facies and coal pore structure characteristics of 15 coal samples were investigated systemically using methods of lithotype analysis maceral analysis proximate analysis mercury porosimetry analysis and nitrogen adsorption analysis these samples were directly collected from the working faces of no 4 8 9 seams in liulin district eastern margin ordos basin china four types of paleoenvironment including a wet forest swamp an intergradation forest swamp a drained forest swamp and a fresh water peat swamp were distinguished by lithotype and merceral analysis an r cluster analysis was performed to demonstrate the correlations between the coal facies and the pore structures the results showed that coal rank is the primary factor affecting the development of micropores and transition pores whereas coal facies control the development of seepage pores in similar coalification conditions especially in a local district and in a seam this work suggests that the vertical variations observed in coal properties macerals vitrinite reflectance mineral matters porosity bet specific area pore size distributions and pores connectivity were controlled by groundwater level fluctuations indicated by variations in the ground water index gwi in the ancient mires due to different accommodation and peat accumulation rates comparison of the porosity characteristics of various coal reservoirs developed in various coal facies indicates that wet forest swamp facies is favorable to the formation of a coalbed methane reservoir because of reasonable pore structure and good connectivity intergradation forest swamp facies rank the second and drained forest swamp facies are less advantageous

bituminite a tem view abstract an illinois coal high volatile bituminous b of carboniferous age containing typical bituminite has been examined by transmission electron microscopy tem to supplement observations with the light microscope with tem the bituminite has a fine fairly regular structure including voids of a characteristic shape this structure is almost certainly inherited from a botanical precursor and is thought to represent much altered remains of former colonies of algae probably green algae the present remains contain abundant lipid rich globules and probably also include matter of algal and bacterial origin which cannot be resolved even at tem resolutions

geological controls on coalbed methane reservoir capacity and gas content the influence of coal composition and rank on coalbed methane reservoir capacity gas content and gas saturation have been investigated for a series of australian canadian and united states coals globally there is no or little correlation between coal rank and methane adsorption capacity as commonly assumed although in particular basins there are general trends with rank and composition micropore1 capacity and surface area determined from low pressure carbon dioxide adsorption isotherms 0 c decrease and then increase with rank passing through a minimum in the high volatile bituminous coal rank there is no consistent variation in modal micropore size or size distribution with rank for suites of isorank coals there is a poor permian bulli and wongawilli seams australia to good positive correlation gates formation coal seams lower cretaceous canada between vitrinite content and methane adsorption capacity dry ash free and as received bases for each isorank coal suite there is a good correlation between micropore capacity and abundance of vitrinite and high pressure methane adsorption capacity comparison of coals of similar composition but from different isorank suites indicates however that the coals with the highest methane adsorption capacity do not necessarily have the highest micropore capacity such results are counterintuitive most pore volume available for methane adsorption is generally assumed to be microporosity it is suspected that moisture prevents methane from accessing some microporosity or competes with methane for adsorption space carbon dioxide micropore capacity which is performed on a dry basis may thus not reflect the microporosity available for gas adsorption in moisture equilibrated coals alternatively because of differing physical and chemical properties of carbon dioxide and methane apparent microporosity available to carbon dioxide due to greater energy of adsorption may not be available to methane total desorbed gas from canister analyses of sydney basin australian coals suggests that most coals are under saturated for a small data set the degree of saturation is negatively correlated with permeability r 0 78 suggesting preferential gas leakage from the higher permeability coals which are vitrite rich some degree of under saturation is probably the result of increased reservoir capacity as a consequence of uplift of the coal seams and thus lower temperatures following gas generation rates of desorption are correlated with total gas content r 0 79 but do not correlate with rank or any compositional parameter

the influence of depositional environments on coal petrographic composition of the lower kittaning seam western pennsylvania abstract lateral variations in maceral composition of the lower kittanning seam can be explained in terms of differential preservation of plant materials which is influenced by the ph eh of water within the peat swamp and by the rate of subsidence within the central part of the basin high telocollinite contents are observed this type of vitrinite represents large well preserved pieces of woody tissue whose preservation was favored by rapid burial towards the margins of the basin high desmocollinite contents are seen slower burial combined with the influx of neutral oxygenated fresh water permitted decomposition of the precursor materials producing this highly degraded type of vitrinite vertical variations in telocollinite and desmocollinite content can also be related to burial rates and ph eh conditions within the swamp throughout the basin high telocollinate contents observed in the lower part of the seam resulted from rapid burial under relatively low ph conditions continued high rates of subsidence led to an influx of neutral ph oxidizing waters associated with the encroaching marine environment under these new conditions more degradation of plant tissues occurred producing the high desmocollinite contents observed in the upper part of the seam this effect was most pronounced in the center of the basin an alternative explanation would be a change in vegetation type in response to the changing conditions the high desmocollinite content would then reflect a shift to a community dominated by smaller possibly herbaceous plants in addition to a change in vitrinite type towards the top of the seam a decrease in total vitrinite content and increases in total liptinite and inertinite contents are observed the increase in liptinite content is due to either 1 the higher resistance to decomposition of liptinite precursor materials when compared to vitrinite precursors in the more neutral conditions or 2 a change from a dominantly arborescent vegetation to a more herbaceous one the increase in inertinite results from an increase in transported material inertodetrinite and or an increase in the formation of inertinite macerals such as degrado fusinite possibly in response to the encroaching marine conditions an additional control on maceral composition is the level of metamorphism of the coal total liptinite content decreases towards the southeast in this area the coal has attained a sufficiently high rank that the reflectance of liptinite macerals approaches that of vitrinite thus making their identification difficult

biogenic origin of coalbed gas in the northern gulf of mexico coastal plain u s a new coal gas exploration and production in northern louisiana and south central mississippi gulf of mexico basin is focused on the wilcox group paleocene eocene where the depth to targeted subbituminous c to high volatile c bituminous coal beds ranges from 300 to 1680 m and individual coal beds have a maximum thickness of about 6 m total gas content generally excluding residual gas of the coal beds ranges from less than 0 37 cm3 g as analyzed or raw basis 1 2 cm3 g dry ash free basis daf at depths less than 400 m to greater than 7 3 cm3 g as analyzed basis 8 76 cm3 g daf in deeper 1 500 m parts of the basin about 20 wilcox coal gas wells in northern louisiana produce from 200 to 6485 m3 of gas day and cumulative gas production from these wells is approximately 25 million m3 as of december 2006 u s geological survey assessment of undiscovered technically recoverable gas resources in the gulf of mexico coastal plain including northern and south central mississippi indicates that coal beds of the wilcox group contain an estimated mean total 109 3 million m3 3 86 trillion ft3 of producible natural gas to determine the origin of the wilcox group coal gases in northern louisiana samples of gas water and oil were collected from wilcox coal and sandstone reservoirs and from under and overlying late cretaceous and eocene carbonate and sandstone reservoirs isotopic data from wilcox coal gas samples have an average 13cch4 value of 62 6 vpdb relative to vienna peedee belemnite and an average dch4 value of 199 9 vsmow relative to vienna standard mean ocean water values of 13cco2 range from 25 4 to 3 42 vpdb produced wilcox saline water collected from oil conventional gas and coalbed gas wells have dh2o values that range from 27 3 to 18 0 vsmow these data suggest that the coal gases primarily are generated in saline formation water by bacterial reduction of co2 shallow 150 m wilcox coal beds containing freshwater have little or no biogenic gas molecular and isotopic analyses of gas samples collected from conventional gas and oil wells suggests that both biogenic and thermogenic gases are present in and adjacent to the wilcox intervals that contain biogenic coal gases oil probably sourced from thermally mature down structural dip parts of the wilcox group is produced from sandstones within the coal bearing interval gas chromatograms of c10 saturated hydrocarbons from wilcox oils show a depletion of n alkanes probably resulting from biodegradation of the oil isotopic composition of the gases associated with the oils is of mixed themogenic and biogenic origin average 13cch4 44 4 vpdb and average dch4 182 4 vsmow