geological controls on gas saturation in the yanchuannan coalbed methane field southeastern ordos basin china abstract the paper investigates lateral variation of gas saturation and its geological controls of the no 2 coal seam in the permian shanxi formation based on coal samples from 21 exploration wells in the yanchuannan coalbed methane cbm field southeastern ordos basin china the data set reveals that gas saturation of the no 2 coal seam shows a high lateral variation from 32 44 to 89 69 and that there is an overall trend in gas saturation with depth overprinted by four other factors 1 influence of faults 2 secondary biogenic gas generation 3 local top seal conditions and 4 variations in coal properties the reverse faults f1 and f2 are effective barriers horizontally for the hydraulic communication and divide our study area into relatively closed and recharge zones gas saturation of the relatively closed zone is generally higher than that in the recharge zone in the recharge gas saturation increases generally along the flow pathway of groundwater with the exceptions of the areas affected by secondary biogenic gas the stable isotope compositions suggest that late stage biogenic methane was generated via co 2 reduction associated with meteoric water recharge which significantly contributes to higher gas saturation than expected meanwhile the biogenic gas generation was is restricted to shallow depths the apparent variations in local areas of lithology of the overlying stratum next to the coal seam suggest that the top seal conditions are deteriorative which can cause gas dissipation and reduce gas saturation remarkably integrally for the variations in coal properties gas saturation has a general positive relationship with coalification and weak negative correlations with moisture content and ash yield but the relationships lacks statistical significances gas saturation is not associated with coal maceral in the study area

characterization of the micropore systems in high rank coal reservoirs of the southern sichuan basin china to gain a better understanding of the characteristics of micropore systems in high rank coal reservoirs 51 coal core samples collected from 16 wells were examined by maceral analysis proximate analysis scanning electron microscopy observation low temperature nitrogen gas adsorption and nuclear magnetic resonance nmr the results show that pores in coals can be divided into plant tissue hole blowhole dissolved pore and intercrystalline pore and they have three structure shapes open pore semiclosed pore and ink bottle pore the total specific surface area brunauer emmet teller bet ranges from 0 611 to 7 to averaged at the total pore volume barrett joyner halenda model bjh ranges from 0 0018 to 0 0001 to with an average of and it shows a good positive relationship with the adsorption amount shows a good positive relationship with the total and the average pore size ranges from 5 775 to 17 842 nm pores that are smaller than 5 nm make up the main contribution to the pore surface area and those larger than 10 nm contribute greatly to the pore volume inertinite rich coals have higher total specific surface area pore volume pore size and adsorption capacity than those in vitrinite rich coals lopingian coal reservoirs are characterized by low porosity and extremely low permeability obtained from nmr tests and the permeability has a positive correlation with the porosity the average permeability of inertinite is almost twice that of vitrinite

the composition and its impact on the methane sorption of lacustrine shales from the upper triassic yanchang formation ordos basin china abstract the organic geochemistry mineralogy and methane sorption of lacustrine shales of the upper triassic yanchang formation collected from the south eastern ordos basin were investigated to characterize them and clarify the effects of shale composition on their sorbed gas capacity these yanchang shales have recently been selected as a target area for shale gas exploration in typical terrestrial strata in china the two main sections of these shales containing type ii organic matters chang 7 and chang 9 have relatively high total organic carbon content toc of 2 10 the two shales also have similar mineralogies mainly comprising quartz clay minerals and feldspars both the chang 7 and chang 9 shales are generally in the oil window chang 9 is slightly more mature than chang 7 higher methane sorption capacity was observed for chang 9 than for chang 7 shales determined on a dried basis at 50 c methane sorption measurements were further performed on three samples from which the residual bitumen had been extracted and their corresponding kerogen fractions to gain insight into the effects of shale composition on methane sorption this was significantly higher in solvent extracted samples than in raw samples indicating that residual bitumen largely restricts methane sorption on such shales a positive correlation between the amount of clay minerals and methane sorption capacity of bulk rocks was evident suggesting that clay mineral content is relevant to methane sorption this result was also supported by the much higher methane sorption capacity of solvent extracted shales compared to the extracted kerogen from those shales when measured sorption data was normalized to toc values the effects of both residual bitumen and clay mineral on the methane sorption of bulk rocks have complicated the evaluation of methane sorption on organic matter in these mature shales

variations in pore characteristics in high volatile bituminous coals implications for coal bed gas content abstract the seelyville coal member of the linton formation pennsylvanian in indiana was studied to 1 understand variations in pore characteristics within a coal seam at a single location and compare these variations with changes occurring between the same coal at different locations 2 elaborate on the influence of mineral matter and maceral composition on mesopore and micropore characteristics and 3 discuss implications of these variations for coal bed gas content the coal is high volatile bituminous rank with r 0 ranging from 0 57 to 0 60 bet specific surface areas determined by nitrogen adsorption of the coals samples studied range from 1 8 to 22 9 m 2 g bjh adsorption mesopore volumes from 0 0041 to 0 0339 cm 3 g and micropore volumes determined by carbon dioxide adsorption from 0 0315 to 0 0540 cm 3 g the coals that had the largest specific surface areas and largest mesopore volumes occur at the shallowest depths whereas the smallest values for these two parameters occur in the deepest coals micropore volumes in contrast are not depth dependent in the coal samples examined for this study mineral matter content influenced both specific surface area as well as mesopore and micropore volumes it is especially clear in the case of micropores where an increase in mineral matter content parallels the decrease of micropore volume of the coal no obvious relationships were observed between the total vitrinite content and pore characteristics but after splitting vitrinite into individual macerals we see that collotelinite influences both meso and micropore volume positively whereas collodetrinite contributes to the reduction of mesopore and micropore volumes there are large variations in gas content within a single coal at a single location because of this variability the entire thickness of the coal must be desorbed in order to determine gas content reliably and to accurately calculate the level of gas saturation

variation in the chemistry of macerals in coals of the mist mountain formation elk valley coalfield british columbia canada abstract variations in elemental and molecular chemistry of macerals with vitrinite semifusinite and sporinite in particular are discussed for the coal seams of the mist mountain formation in the elk valley coalfield in western canada in the south elk valley coalfield carbon content of vitrinite oscillates around 85 and oxygen content increases gradually up section from seam a to c in the north elk valley coalfield carbon content in vitrinite shows marked variations from 70 to 85 between the samples and is lower than in the south elk valley coalfield which is consistent with a higher maturation level of south elk valley coalfield samples sulphur content is below 1 in both coalfields semifusinite in general has higher carbon and lower oxygen content than vitrinite whereas cutinite has higher carbon content than vitrinite and slightly higher or comparable to that of semifusinite functional group distributions show large variations between the seams and these variations are attributed mainly to differences in a primary depositional environment and only occasionally to later weathering and oxidation processes the results presented in this paper provide also information on the length and branching of aliphatic chains which for liptinite macerals is valuable from the oil generation viewpoint whereas for semifusinite it may help to understand reactive versus non reactive behaviour during coking

isotope variations of dissolved zn in the rio grande watershed usa the role of adsorption on zn isotope composition abstract in order to better understand the factors influencing zinc zn isotope composition in hydrological systems we analyzed the 66 zn of dissolved zn in the streams and groundwater of the upper and middle rio grande watershed in colorado and new mexico united states the stream water samples have a wider variation of 66 zn 0 57 to 0 41 relative to the jmc 3 0749 lyon standard than groundwater samples 0 13 to 0 12 and than samples from streams that are in close proximity to abandoned mining sites 0 24 to 0 40 regional changes of bedrock geology from primarily igneous rocks to primarily sedimentary rocks have no resolvable effect on the 66 zn of aqueous samples instead an increase in water ph from 7 5 to 8 5 corresponds to a considerable decrease in the 66 zn of dissolved zn r 2 0 37 p 0 003 n 22 consequently we link the observed zn isotope variations to the process of adsorption of zn onto suspended sediment and bedrock minerals average 66 zn adsorbed dissolved 0 31 our results are in good agreement with previous experimental and empirical studies suggesting that zn adsorption leads to a residual dissolved pool enriched in light zn isotopes given that anthropogenic zn sources can also be responsible for lowering of 66 zn and may overlap with the ph adsorption effect on 66 zn the latter needs to be carefully considered in future studies to differentiate between natural and anthropogenic factors influencing zn isotopes in this and other aquatic systems

evolution of methane sorption capacity of coal seams as a function of burial history a case study from the campine basin ne belgium based on extensive data sets of high pressure sorption isotherms and canister desorption data from two central european coal basins campine and ruhr basins a computational scheme has been developed to calculate the maximum coal bed methane cbm sorption capacity of coal seams as a function of pressure temperature and coal rank in addition the effects of in situ moisture content and maceral composition have been tentatively implemented using this algorithm it is possible to explicitly take into account variations in sorption capacity of the coal seams in sedimentary basins over geologic time as a function of burial history and thermal evolution the procedure has been applied to model the evolution and the present day coal bed methane content of the campine basin ne belgium it is demonstrated how the present day gas content of the campine basin is controlled by the burial history of the coal layers throughout geologic time the maximum gas sorption capacity typically occurs at a depth range between 500 and 1000 m during periods of uplift and erosion 250 and 90 ma before present the uppermost coal layers have lost methane due to a reduction of gas storage capacity while their storage capacity has increased during periods of burial 300 and 180 ma ago and present additionally the present day gas content is controlled by the gas generation history coal layers which have lost storage capacity during geologic time will stay undersaturated if not replenished by late stage e g microbial gas the gas content profile of test well kb206 in the ne campine basin established from canister desorption tests can be reproduced by assuming that undersaturation of the coals is due to erosion and re burial and that no significant gas generation e g microbial gas has taken place after the time of maximal burial isotopic data d 178 13c 59 indicate the presence of a small portion of microbial gas the absolute gas contents in this well are lower than the calculated maximum present day sorption capacity this may be due to an underestimation of the effect of water content on sorption capacity or result from degassing via nearby faults enforced by fluid circulation

high pressure methane and carbon dioxide sorption on coal and shale samples from the parana basin brazil abstract an experimental study has been conducted to assess the potential for coalbed methane production and carbon dioxide storage in coals carbonaceous shales and source rocks in the parana basin in brazil high pressure sorption tests with methane and carbon dioxide were performed on coal and carbonaceous shales from the santa terezinha coalfield and samples from two principal petroleum source rocks measured excess sorption capacities ranged from 0 03 to 0 47 mmol g for methane and 0 14 to 0 81 mmol g for carbon dioxide showing a decrease with decreasing organic matter content linear regression lines for methane sorption capacity vs toc extrapolated to approximately zero whereas for carbon dioxide the intercept of the regression line indicated a residual sorption capacity of 0 2 mmol g on the mineral matter present day gas contents of coals collected from the first cbm well in the santa terezinha coalfield correspond to 13 38 of the measured maximum sorption capacities carbon dioxide sorption capacities exceed methane sorption capacities by a factor of 1 9 to 6 9 for these coals free sorption capacities of the under saturated coals in combination with preferential sorption of carbon dioxide could favour co 2 enhanced methane recovery and co 2 storage in coals and shales of the study area based upon the calculated coal reserves gas contents and measured sorption capacities a total storage potential of 15 4 gt co 2 was estimated for an area of 20 40 km 2 in the santa terezinha coal field assuming a combined co 2 enhanced coalbed methane ecbm production and co 2 storage operation to fully evaluate the potential for carbon dioxide storage and coalbed methane production further studies are required to assess producibility of methane and efficiency of long term co 2 storage in the study area

organic matter mineral composition pore size and gas sorption capacity of lacustrine mudstones implications for the shale oil and gas exploration in the dongying depression eastern china because clay minerals and pore size distribution are important for oil and gas accumulation in lacustrine mudstone reservoirs this study aimed to characterize the pore size distribution in lacustrine mudstone reveal the importance of clay minerals in gas sorption capacity gsc provide insights into the primary gsc controls for lacustrine mudstones and discuss the shale oil and gas resource potential and possible risks in their future production a total of 256 core samples from the lower paleogene sequence of the dongying depression in the bohai bay basin in china were analyzed to determine organic richness and hydrocarbon generation potential a series of analyses was conducted on a suite of 28 mudstone samples from the s121 well to investigate the mineral composition pore size distribution and primary controls on gsc scanning electron microscopy and x ray diffraction were used to observe the microscopic characteristics and identify various minerals nitrogen adsorption experiments at low temperatures and a methane isothermal adsorption test were conducted to study the pore sizes and gas adsorption capacities experimental results show that the majority of the samples were rich in type ii and i kerogen with moderate to high hydrocarbon generation potential and are thermally mature in the main oil window the contents of illite and mixed layer illite smectite i s are high 40 in these lacustrine mudstones the pores were mainly thin long and bottleneck shaped and dominated by type iv and h2 hysteresis loop characteristics the abundance of quartz feldspar illite and mixed layer i s all presented a positive correlation with their brunauer emmett teller surface area and total pore volume whereas the abundance of carbonate minerals dominated by calcite showed a negative correlation the volume of micropores and clay minerals were the main factors controlling gscs the results highlight the importance of clay minerals including the illite and mixed layer i s in the lacustrine mudstones because of their considerable gsc high content of illite and mixed layer i s in lacustrine mudstone is in favor of gas storage whereas at the same time it is not conducive to shale gas development because of its reducing the brittleness of shale the paleogene of dongying depression has shale oil and gas resources however several key geological factors including pore size distributions pore diameters oil density and low brittleness may pose risks in shale oil and gas development

the importance of shale composition and pore structure upon gas storage potential of shale gas reservoirs abstract the effect of shale composition and fabric upon pore structure and ch 4 sorption is investigated for potential shale gas reservoirs in the western canadian sedimentary basin wcsb devonian mississippian d m and jurassic shales have complex heterogeneous pore volume distributions as identified by low pressure co 2 and n 2 sorption and high pressure hg porosimetry thermally mature d m shales 1 6 2 5 vro have dubinin radushkevich d r co 2 micropore volumes ranging between 0 3 and 1 2 cc 100 g and n 2 bet surface areas of 5 31 m 2 g jurassic shales which are invariably of lower thermal maturity ranging from 0 9 to 1 3 vro than d m shales have smaller d r co 2 micropore volumes and n 2 bet surface areas typically in the range of 0 23 0 63 cc 100 g co 2 and 1 9 m 2 g n 2 high pressure ch 4 isotherms on dried and moisture equilibrated shales show a general increase of gas sorption with total organic carbon toc content methane sorption in d m shales increases with increasing toc and micropore volume indicating that microporosity associated with the organic fraction is a primary control upon ch 4 sorption sorption capacities for jurassic shales however can be in part unrelated to micropore volume the large sorbed gas capacities of organic rich jurassic shales independent of surface area imply a portion of ch 4 is stored by solution in matrix bituminite solute ch 4 is not an important contributor to gas storage in d m shales structural transformation of d m organic matter has occurred during thermal diagenesis creating and or opening up microporosity onto which gas can sorb as such d m shales sorb more ch 4 per weight percent wt toc than jurassic shales inorganic material influences modal pore size total porosity and sorption characteristics of shales clay minerals are capable of sorbing gas to their internal structure the amount of which is dependent on clay type illite and montmorillonite have co 2 micropore volumes of 0 78 and 0 79 cc 100 g n 2 bet surface areas of 25 and 30 m 2 g and sorb 2 9 and 2 1 cc g of ch 4 respectively dry basis a reflection of microporosity between irregular surfaces of clay platelets and possibly related to the size of the clay crystals themselves mercury porosimetry analyses show that total porosities are larger in clay rich shales compared to silica rich shales due to open porosity associated with the aluminosilicate fraction clay rich sediments low si al ratios have unimodal pore size distributions

meso and microporosity of the subbituminous km2 coal seam soma turkey and its relationship with coal characteristics abstract this study focuses on meso and microporosity of the subbituminous km2 coal seam and its relation to coal characteristics the coal seam is being mined in an underground coal mine at the eynez sector in the soma basin western turkey the analysed coal samples are characterized by low moisture avg 8 2 on air dry basis and total s content avg 1 5 on dry basis and moderate ash yield avg 26 1 on dry basis the predominant maceral group is huminite in which telohuminite is the dominant maceral subgroup up to 57 1 vol on whole coal basis whereas liptinite and inertinite maceral groups occur in low but variable proportions mineralogically the samples are composed of quartz clay minerals kaolinite and illite carbonates pyrite and rarely feldspars and gypsum statistical and sem edx analyses indicate that the majority of elements have inorganic affinity particularly the aluminosilicate minerals the specific surface area and volume of mesopores and average mesopore size determined by low pressure n2 adsorption range widely throughout the studied seam section micropore characteristics analysed by low pressure co2 adsorption demonstrate that micropores are abundant and specific surface area and volume of micropores vary widely surface area and volume of mesopores are slightly higher in the lower part of the seam whereas the opposite was observed for surface area and volume of microspores these trends may imply that hydrostatic pressure has little impact upon mesopore characteristics although increased ash yields in the lower part of the seam suggest that minerals are the major contributor of coal mesopores furthermore total c contents and huminite macerals particularly telohuminite display positive correlations with micropore characteristics thus the variations in the microporosity are mainly correlated with the proportion of organic matter macerals in the analysed samples the contents of aluminosilicate affiliated elements display moderate to strong positive correlations with surface area and volume of mesopores and total s and b contents display weak positive correlations with surface area and volume of micropores the element b likely precipitated from porewater or intra seam solutions during coalification and was absorbed by macerals having abundant microporosity the abundance of micropores along with frequent disseminated pyrite crystals within the reactive macerals telohuminite group and higher total s contents in the upper parts of the seam could increase the risk of self heating therefore care should be taken to use caution when mining the upper part of the seam

the diavik waste rock project particle size distribution and sulfur characteristics of low sulfide waste rock three large scale instrumented waste rock piles were constructed at the diavik diamond mine in the northwest territories canada these experimental waste rock piles test piles are 15 m high and are part of an integrated field and laboratory research program to characterize and compare low sulfide waste rock and drainage at various scales during test pile construction samples of the 0 08 wt s for the higher s waste rock type the third test pile has a low permeability till layer and a low sulfide waste rock thermal layer covering a core of waste rock with average 0 082 wt s in the 0 08 wt s for the higher s waste rock particle size distributions for the lower and higher s waste rock are similar but the higher s waste rock has a higher proportion of fine grained particles sulfur determinations for discrete particle sizes of the 10 m scale from composite blast hole cuttings are lower than those calculated for the 0 05 wt s is of uncertain acid generating potential and effluent data indicate this waste rock generates acidic effluent whereas lower s waste rock does not produce acidic effluent consistent with the acid base accounting predictions

the diavik waste rock project measurement of the thermal regime of a waste rock test pile in a permafrost environment abstract the interior thermal regime of a field scale experimental waste rock pile in the northwest territories canada was studied test pile construction was completed in the summer 2006 and temperature data was collected continuously since that time to february 2009 the temperature data indicates the test pile cooled over the study period with an average heat energy release of 2 5 104 and 2 6 104 mj in 2007 and 2008 respectively the mean annual air temperature maat at the site was 8 9 c during the period between 2006 and 2009 with a permafrost table at a depth of 4 m in bedrock away from the pile because of this cold environment the upward movement rate of the 0 c isotherm into the test pile at its base was approximately 1 5 m a 1 during 2007 and 2008 thermistor strings installed immediately below the base of the test pile showed the test pile basal temperatures remained near and below 0 c during the study period furthermore due to low rates of sulfide mineral oxidation elevated temperatures in the interior of the test pile were not observed the average air velocity in the pore space in july 2007 and 2008 was about one third of that during january of each year based on temperature distributions therefore due to higher air velocity during the winter it is expected that heat transfer is greater during winter

revisiting steady state water flow in a saturated inclined soil slab mathematical models of flow in a saturated inclined soil slab with an impermeable lower boundary have contributed substantially to understanding of important processes in the environment one such process is movement of chemicals induced by interflow in sloping soil certain aspects of previous mathematical treatment regarding the inclined soil slab problem have however escaped scrutiny the original 1965 treatment includes a peculiar quadratic boundary condition term that applies over a vanishingly small fraction of the soil surface the quadratic term is shown to be unjustified and unnecessary in obtaining practical solutions mathematical solutions of two more general inclined slab geometries three dimensional and parallelogram slabs are presented and solved the solutions are illustrated in terms of figures showing selected flow paths and equipotentials

origin and accumulation of petroleum in deep precambrian reservoir in baxian sag bohai bay basin china abstract the baxian sag is a mature exploration area the exploitation of deep sedimentary formation is becoming increasingly important as the further development potential of shallow plays faces growing challenges the discovery of the niudong gas condensate field from deep precambrian reservoirs indicates that potentially significant hydrocarbon resources remain to be discovered in deeper stratigraphic units this study was undertaken to better understand the generation and accumulation of hydrocarbons in deep reservoirs through integrated petroleum geochemistry fluid inclusion analysis and source rock analysis geochemical parameters of condensate and gas suggest that condensate and gas in precambrian reservoir have similar thermal maturity and are directly derived from gas prone source rock at high maturity levels the regional structure section and hydrocarbon distribution indicate that gas condensate in the nd1 well is more likely derived from lacustrine source rock in the paleogene shahejie formation refined source kitchen analysis indicates that lacustrine source rocks in the shahejie formation display a high degree of heterogeneity including organo facies c d e and f differences in the nature and composition of the expelled petroleum exist between organo facies due to variations in kerogen composition the orderly spatial distributions of gas oil ratio gor api gravity and gas carbon isotopes denote that the various fronts expelled hydrocarbons at different maturity levels from different organo facies this reflects the dynamic scenario of petroleum migration and accumulation from kitchen to shallow reservoirs the precambrian reservoir in nd1 well has experienced multiple charging with hydrocarbon expulsion at different maturity levels while hydrocarbons of lower maturity have arrived into the shallower reservoirs condensate and gas expelled at high maturation levels have efficiently accumulated in deeper prospects

organic matter hosted pore system marcellus formation devonian pennsylvania the marcellus formation of pennsylvania represents an outstanding example of an organic matter om hosted pore system most pores detectable by field emission scanning electron microscopy fe sem are associated with om instead of mineral matrix in the two wells studied here total organic carbon toc content is a stronger control on om hosted porosity than is thermal maturity the two study wells span a maturity from late wet gas vitrinite reflectance ro 1 0 to dry gas ro 2 1 samples with a toc less than 5 5 wt display a positive correlation between toc and porosity but samples with a toc greater than 5 5 wt display little or no increase in porosity with a further increasing toc in a subset of samples 14 across a range of toc 2 3 13 6 wt the pore volume detectable by fe sem is a small fraction of total porosity ranging from 2 to 32 of the helium porosity importantly the fe sem visible porosity in om decreases significantly with increasing toc diminishing from 30 of om volume to less than 1 of om volume across the range of toc the morphology and size of om hosted pores also vary systematically with toc the interpretation of this anticorrelation between om content and sem visible pores remains uncertain samples with the lowest om porosity higher toc may represent gas expulsion pore collapse that was more complete as a consequence of greater om connectivity and framework compaction whereas samples with higher om porosity lower toc correspond to rigid mineral frameworks that inhibited compactional expulsion of methane filled bubbles alternatively higher toc samples may contain om low initial hydrogen index relatively unreactive that is less prone to development of fe sem detectable pores in this interpretation om type controlled by sequence stratigraphic position is a factor in determining pore size distribution

microfracturing and microporosity in shales shales are ubiquitous rocks in sedimentary basins where their low permeability makes them efficient seals for conventional oil and gas reservoirs and underground waste storage repositories waste waters co2 nuclear fuels moreover when they contain organic matter they form source rocks for hydrocarbons that may escape towards a more porous reservoir during burial a process referred to as primary migration and when the hydrocarbons cannot escape these rocks can be exploited as oil or shale gas reservoirs while the presence of fractures at the outcrop scale has been described the existence of fractures at smaller scales their link with microporosity the mechanisms that created them their persistence over geological times and their effect on the petrophysical properties of shales represent scientific challenges for which drillings in various sedimentary basins over the past decades may hold timely key data here we review and synthetize the current knowledge on how microfractures and micropores in shales can be imaged and characterized and how they control their anisotropic mechanical properties and permeability one question is whether such microfractures when observed in outcrops or in drilled core samples extracted from boreholes are related to decompaction and do not exist at depth another question is whether veins observed in shales represent microfractures that were open long enough to have acted as flow paths across the formation the mechanisms of microfracture development are described some have an internal origin fracturing by maturation of organic matter dehydration of clays while others are caused by external factors tectonic loading importantly the amount of microfracturing in shales is shown to depend strongly on the content in 1 organic matter and 2 strong minerals the nucleation of microfractures depends on the existence of mechanical heterogeneities down to the nanometer scale their propagation and linkage to create a percolating network will depend on the presence of heterogeneities at the meso to macro scales such percolating microfracture networks could control both the long term sealing capabilities of cap rocks and the further propagation of hydraulic fracturing cracks finally possible areas of research for describing the mechanism of microfracture formation in greater detail and how this impacts the transport and mechanical properties of shales are also discussed

accommodation based coal cycles and significant surface correlation of low accommodation lower cretaceous coal seams lloydminster heavy oil field alberta canada implications for coal quality distribution sequence stratigraphy and coal cycles based on accommodation trends were investigated in the coal bearing lower cretaceous mannville group in the lloydminster heavy oil field eastern alberta the study area is in a low accommodation setting on the cratonic margin of the western canada sedimentary basin geophysical log correlation of coal seams shoreface facies and the identification of incised valleys has produced a sequence stratigraphic framework for petrographic data from 3 cored and 115 geophysical logged wells maceral analysis telovitrinite reflectance and fluorescence measurements were taken from a total of 206 samples three terrestrial depositional environments were interpreted from the petrographic data ombrotrophic mire coal limnotelmatic mire coal and carbonaceous shale horizons accommodation based coal wetting and drying upward cycles represent trends in depositional environment shifts and these cycles were used to investigate the development and preservation of the coal seams across the study area the low accommodation strata are characterized by a high frequency occurrence of significant surfaces coal seam splitting paleosol and incised valley development three sequence boundary unconformities are identified in only 20 m 66 ft of strata coal cycle correlations illustrate that each coal seam in this study area was not produced by a single peat accumulation episode but as an amalgamation of a series of depositional events complex relations between the cummings and lloydminster coal seams are caused by the lateral fragmentation of strata resulting from the removal of sediment by subaerial erosion or periods of nondeposition syndepositional faulting of the underlying basement rock changed local accommodation space and increased the complexity of the coal cycle development this study represents a low accommodation example from a spectrum of stratigraphic studies that have been used to establish a terrestrial sequence stratigraphic model the frequency of changes in coal seam quality is an important control on methane distribution within coalbed methane reservoirs and resource calculations in coal mining a depositional model based on the coal cycle correlations as shown by this study can provide coal quality prediction for coalbed methane exploration reservoir completions and coal mining

the pore structural evolution of the marcellus and mahantango shales appalachian basin abstract the generation and primary migration of hydrocarbons in organic rich shale leaves void space in organic matter which is the porosity associated with organic matter commonly observed under scanning electron microscope sem in this study middle devonian black shale core samples were collected from three wells penetrating the organic rich marcellus shale and the organic lean mahantango formation in pennsylvania and west virginia pyrolysis ion milled sem and low pressure nitrogen adsorption analysis were conducted to investigate the organic richness and the properties of the pore system vitrinite reflectance ro values in the range of 1 36 2 89 represent a maturity spectrum covering the wet gas to post mature zones in general the pore system is composed of organic matter hosted pores and mineral hosted pores however the dominant pore types and pore sizes vary stratigraphically across lithology and abundance of organic matter all the organic matter observed in this study shows an amorphous occurrence pore space between mineral grains both silt size and clay size can be filled by organic matter which contains secondary porosity generated by thermal cracking of kerogen mineral hosted pores are concentrated in organic lean samples in which secondary organic matter could not fill most of the primary pore space the destruction of primary mineral hosted pores and the generation of secondary organic matter hosted pores were observed toc values show positive correlations with the porosity specific surface area and the abundance of micropores increasing thermal maturity correlates with a significant decrease of pore volume and surface area primarily through diminishing or vanishing of micropores the richness and thermal maturity of organic matter in organic rich devonian shale can be effective parameters for evaluation of reservoir quality and upscaling the appraisal

light volatile liquid and gas shale reservoir potential of the cretaceous shaftesbury formation in northeastern british columbia canada the geologic controls on reservoir properties and potential hydrocarbon volatile low molecular weight liquid and gas resources of the cretaceous shaftesbury formation in northeastern british columbia have been investigated maturity varies from the oil to dry gas window tmax 429 486c with increasing maturity and depth of burial toward the south the tmax in degrees celsius is the oven temperature at the peak generation of s2 during pyrolysis total organic carbon toc content ranges between 0 64 and 8 0 wt with an average of 2 2 wt the toc content distribution mirrors the trends in maturity with lower toc content in areas of high maturity kerogen is characterized as either type ii iii or type iii the quartz content ranges between 33 and 66 with higher quartz content in areas with lower toc content and greater maturities porosity ranges between 4 5 and 14 6 with higher porosities observed within shallower wells low quartz content or maturities or a combination of all three the porosity is reduced in high maturity samples by mechanical compaction and silica cementation total gas capacities range between 4 5 and 24 8 cm3 g and gas in place gip estimates are between 0 98 and 3 39 bcf section meter the calculated hydrocarbon generation is less than 3 6 bcf section meter with light liquid generation between 3 7 and 516 2 mmbo present day depths and organic maturity have strong influences on the hydrocarbon capacity more so than toc content deeper higher maturity samples in the south have the largest total gas capacity and gip estimates 0 98 3 39 bcf section meter maturity is within the dry gas window in the southern one third of the study area highest volumes of light liquid hydrocarbons are found within the less mature northern part of the study area

the diavik waste rock project design construction and instrumentation of field scale experimental waste rock piles the physicochemical processes that affect acid mine drainage amd in unsaturated waste rock piles and the capabilities of small scale laboratory experiments to predict amd from waste rock are not well understood an integrated laboratory and field study to measure and compare low sulfide waste rock and drainage characteristics at various scales has been initiated this paper describes the design construction and instrumentation of three field scale experimental waste rock piles test piles and six active zone lysimeters at the diavik diamond mine in the northwest territories canada the test piles are comprised of granitic and sulfide bearing metasedimentary waste rock excavated during open pit mining operations one test pile contains waste rock with a target s content of 0 08 wt s and the third test pile contains the higher sulfide waste rock 0 08 wt s and was re sloped and capped with a low permeability till layer and a low sulfide waste rock cover the first two test piles are approximately 15 m high with bases of 50 m by 60 m and the re sloped test pile has a larger base of 80 m by 125 m instrumentation was selected to measure matrix flow geochemistry of pore water and drainage gas phase o2 concentration temperature evolution microbiological populations waste rock permeability to air and thermal conductivity as well as to resolve mass and flow balances instrument locations were selected to characterize coupled physicochemical processes at multiple scales and the evolution of those processes over time instruments were installed at a density such that the number of instruments that survived construction 40 to 80 by instrument type was sufficient to allow adequate characterization of the physicochemical processes occurring at various scales in the test piles

mineral matter in coals cleat minerals and their origin in some coals from the english midlands abstract in four coal seam profiles from the cannock coalfield west midlands the cleat joint frequency is a function of lithotype greatest in vitarin and is inversely related to bed thickness the cleat minerals were studied 1 under the microscope optical and electron 2 by x ray diffraction and 3 chemically the minerals present are pyrite marcasite sphalerite galena sulphides quartz kaolinite silicates ankerite calcite carbonates and apatite this sequence has features in common with diagenetic sequences recorded in other rock types and it is concluded that the cleat minerals in coal form in response to pore fluid evolution and movement during burial diagenesis the elements are thought to originate from both the coal and the associated sediments mainly mudrocks similarities in diagenetic sequences are in part a reflection of the importance of organic maturation reactions in all the rock types in the sequence whereas differences are attributed to the dominance of these reactions in the coal itself

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

coal petrology and coal seam gas contents of the walloon subgroup surat basin queensland australia abstract core exploration and appraisal drilling over the last four years have targeted the juandah upper and taroom lower coal measures of the middle jurassic walloon subgroup of the injune creek group these wells have shown that the high volatile bituminous perhydrous coals of the walloon subgroup have gas contents of between 1 and 14 m 3 t and some wells have encountered gas flows at rates of over 30 000 m 3 day this recent work has confirmed the initial supposition that the coals within the walloon subgroup contain sufficient quantities of gas to be economically viable as a coal seam gas source coal volumes depth and structure have also been confirmed from the initial work what has become apparent during this work is the variability in gas content across each of the seams in the juandah and taroom coal measures and the variability in coal petrographic composition of these two units are controlled by many factors what has also become apparent is that the taroom coal measures have a lower average gas content than the overlying juandah coal measures the obvious conclusion is that the difference in gas content is related to a difference in coal petrology not only do the gas contents of these coal intervals differ their gas adsorption capacities also differ with the taroom coal measures coals displaying on average lower gas content and lower gas adsorption capabilities again the obvious cause would be coal petrological differences but the juandah and taroom coal measures coals have similar maceral percentages an understanding of the relationship between gas desorption gas adsorption and coal composition is vital in determining which areas in the basin offers the most economically viable targets for the commercialisation of coal seam gas in the surat basin

comparison of pore systems of clay rich and silica rich gas shales in the lower silurian longmaxi formation from the jiaoshiba area in the eastern sichuan basin china abstract the jiaoshiba area in the eastern sichuan basin hosts the largest commercial shale gas field in china with an annual production of 1 7 bcf the gases are primarily produced from the clay rich siliceous marine shales in the wufeng and longmaxi formations in this paper sixteen organic rich shale samples from a variety of lithofacies from the longmaxi formation in the jiaoshiba area were studied to evaluate the pore systems of clay rich shales by comparison with the silica rich gas shales the investigation includes the assessment of porosity and pore size distribution by means of shale bulk and skeletal density measurements low pressure n2 co2 gas adsorption and mercury intrusion the shale samples with different lithofacies have porosity values ranging from 3 25 to 5 65 and display similar fractional volumes of micropores mesopores and macropores and corresponding specific surface areas all three pore fractions contribute to the shales total pore volumes while the total specific surface areas are mainly contributed to by micropores and mesopores there is a positive correlation between pore volumes and toc contents indicating that the porosities in the shales are dominated by organic matter pores with toc content being the main parameter controlling pore development toc normalized pore volumes decrease with a further increase in the toc content from 1 6 to 4 2 this may be related to the fact that the toc rich shales are more susceptive to mechanical compaction clay mineral content appears to have little effect on the pore volume or specific surface area development in the shales shale samples with clay rich siliceous shale lithofacies display similar toc contents porosities and fractional volumes of all pore sizes and specific surface areas with those of the silica rich argillaceous and argillaceous siliceous mixed lithofacies this suggests that the marine shales with silica rich argillaceous and argillaceous siliceous mixed lithofacies from the longmaxi formation in the jiaoshiba area are capable of generating significant amount of pore spaces for shale gas storage

zn and cu isotopic variability in the alexandrinka volcanic hosted massive sulphide vhms ore deposit urals russia abstract copper and zn isotope ratios of well characterized samples from three ore facies in the devonian alexandrinka volcanic hosted massive sulphide vhms deposit southern urals were measured using multi collector icp ms mc icp ms and show variations linked to depositional environment and mineralogy the samples analysed derived from a hydrothermal metasomatic vein stockwork b a hydrothermal vent chimney and c reworked clastic sulphides as the deposit has not been significantly deformed or metamorphosed after its formation it represents a pristine example of ancient seafloor mineralization variations in 65 cu where 65 cu 65 cu 63 cu sample 65 cu 63 cu standard 1 1000 and 66 zn where 66 zn 66 zn 64 zn sample 66 zn 64 zn standard 1 1000 of 0 63 and 0 66 respectively are significantly greater than analytical uncertainty for both isotope ratios 0 07 2 very limited isotopic fractionation is observed in primary cu minerals from the stockwork and chimney whereas the zn isotopic composition of the stockwork varies significantly with the mineralogy chalcopyrite bearing samples from the stockwork have lighter 66 zn by 0 4 relative to sphalerite dominated samples which may be due to equilibrium partitioning of isotopically light zn into chalcopyrite during its precipitation 66 zn also showed significant variation in the chimney with an enrichment in heavy isotopes toward the chimney rim of 0 26 which may be caused by changing temperature hence fractionation factor or raleigh distillation post depositional seafloor oxidative dissolution and re precipitation in the clastic sediments possibly coupled with leaching led to systematic negative shifts in cu and zn isotope compositions relative to the primary sulphides copper shows the most pronounced fractionation consistent with the reduction of cu ii to cu i during supergene mineralization however the restricted range in 65 cu is unlike modern sulphides at mid oceanic ridges where a large range of cu isotope of up to 3 has been observed rouxel o fouquet y ludden j n 2004 copper isotope systematics of the lucky strike rainbow and logatchev sea floor hydrothermal fields on the mid atlantic ridge econ geol 99 585 600 zhu x k o nions r k guo y belshaw n s rickard d 2000 determination of natural cu isotope variation by plasma source mass spectrometry implications for use as geochemical tracers chem geol 163 139 149

evaluating the gas content of coals and isolated maceral concentrates from the paleocene guasare coalfield venezuela abstract this work presents the results from evaluating the gases sorbed by coal samples extracted from the paleocene guasare coalfield marcelina formation northwestern venezuela as well as by their distinct maceral concentrates the aim of this work has been to obtain an initial experimental main value of the gas content per unit weight of high volatile bituminous a coal samples from the open pit paso diablo mine an additional goal was to study differences in the ch 4 storage ability of the distinct maceral groups forming part of the coal matrix both the coal samples and the maceral concentrates were studied by thermogravimetric analysis tga in order to determine the temperature to be used in subsequent experiments on line analyses of hydrocarbons c 1 c 2 c 3 and co 2 yielded gas concentrations plus 13 c values thermogenic gas is prevalent in the guasare coals with vitrinite reflectance r o values from 0 65 to 0 88 the amount of gas retained in the coals and maceral concentrates was measured with a special device that allows determination of the volume of gas sorbed by a solid sample subjected to controlled thermal treatment the average coalbed gas concentration obtained was 0 51 cm 3 g the following list of maceral concentrates shows the relative capacity for the volume of sorbed gas per unit weight inertinite low density vitrinite liptinite high density vitrinite it is concluded that the gas volumes retained in the distinct maceral concentrates are not controlled by porosity but rather by their microscopic morphology

pore structure evolution of low rank coal in china abstract in china low rank coalbed methane cbm resources are in the early stage of exploration the evolution of pore structure for these coals around the first coalification jump is incomplete here systematic experiments were conducted to analyze the reservoir of low rank coal lignite and subbituminous coal from china s major low rank basins thus revealing the pore structure evolution of low rank coal in china scanning electron microscopy sem demonstrates that there are obvious differences in the pore types of different rank coals well developed cell lumina provides a large amount of macropore space in coals with ro

hydrogeologic factors affecting gas content distribution in coal beds gas content in coal is not fixed but changes when equilibrium conditions within the reservoir are disrupted therefore gas content distribution in coal varies laterally within individual coal beds vertically among coal beds in a single well and within thicker coal beds major hydrogeologic factors affecting gas content variability include gas generation coal properties and reservoir conditions gas generation affects gas content variability on a regional scale whereas coal properties influence gas content distribution on a regional and local scale reservoir conditions affect gas content more locally within specific fields or individual wells the potential for high gas content is controlled directly by the amount of thermogenic and secondary biogenic gases generated from the coal which in turn are controlled by burial history maceral composition and basin hydrodynamics variability in mineral matter ash and moisture content sorption behavior among macerals diffusion coefficients and permeability result in heterogeneous gas content distribution gas content decreases with decreasing pressure and temperature and coal beds become undersaturated with respect to methane during basin uplift and cooling gas content generally increases where conventional and hydrodynamic trapping of coal gases occur and may decrease in areas of active recharge with downward flow potential and or convergent flow where there is no mechanism for entrapment

organic petrology geochemistry gas content and gas composition of middle pennsylvanian age coal beds in the eastern interior illinois basin implications for cbm development and carbon sequestration abstract fifty four samples of coal and organic rich roof shale strata were collected as part of a coal bed methane exploration program following canister desorption to document gas contents the samples were analyzed by geochemical and petrographic methods coal samples were found to have moderate ash yields avg 13 5 dry basis and high total sulfur contents avg 4 3 dry basis the average gas content was 1 91 m3 ton petrographically the coals were dominated by vitrinite macerals avg 81 6 mmf especially telovitrinite by comparison liptinite avg 7 1 mmf and inertinite macerals avg 11 3 mmf were minor in occurrence coal samples ranged from high volatile c to high volatile a bituminous in rank avg ro maximum 0 76 shale samples had higher ash yields avg 76 1 dry basis though total sulfur contents were comparable to the coal samples avg 4 2 dry basis gas contents were lower than the corresponding coal samples avg 0 65 m3 ton petrographically the shale samples contained decreased amounts of vitrinite avg 25 6 mmf and higher amounts of liptinite avg 45 4 mmf and inertinite avg 29 0 mmf macerals relative to the coal samples gas obtained from coal and shale beds in the illinois basin was relatively pure high ch4 content limited data also indicated that illinois basin coals have the ability to adsorb fairly significant amounts of co2 this suggests that co2 injection to enhance methane production ecbm and or to sequester co2 may have some potential mineralization in the coals could negatively impact cbm production but it was found that the majority of the mineralization was present in the roof strata

zinc isotope variations in deep sea carbonates from the eastern equatorial pacific over the last 175 ka the carbonate fraction of sediment core odp 849 leg 138 located in the eastern equatorial pacific mostly consisting of coccoliths was separated and analyzed for its zn isotopic composition the overall variation in zn isotopic composition as determined by multiple collector magnetic sector inductively coupled plasma mass spectrometry was found to be on the order of 1 expressed in 66zn where xzn xzn 64zn sample xzn 64zn standard 1 103 and x 66 67 or 68 over the last 175 ka the analytical precision was 0 04 and the overall reproducibility was usually better than 0 07 the zn isotopic composition signal exhibits several marked peaks and a high frequency variability a periodogram of the 66zn signal showed two periodicities of 35 2 and 21 2 ka we suggest that the latter is caused by the precession of the earth s axis of rotation the periodogram exhibits a minimum at 41 1 ka thus showing that the zn isotopic composition is independent of the obliquity in the eastern equatorial pacific the range of 66zn values observed for the carbonate fraction of odp 849 overlaps with the range observed for fe mn nodules in the world s oceans which suggests that seawater carbonate zn isotope fractionation is weak we therefore assume that most of the zn isotope variability is a result of the selective entrainment of the light isotopes by organic matter in the surface ocean the odp 849 66zn record seems to follow the changes in the insolation cycles changes in the late summer fall equatorial insolation modulate the intensity of the equatorial upwelling hence the mixing between deep and surface waters we propose that during decreased summer fall equatorial insolation when a steep thermocline can develop el nino like conditions the surface waters cannot be replenished by deep waters and become depleted in the lighter zn isotopes by biological activity thus resulting in the progressive increase of the 66zn values of the carbonate shells presumably in equilibrium with surface seawater

characterizing the shale gas resource potential of devonian mississippian strata in the western canada sedimentary basin application of an integrated formation evaluation devonian mississippian strata in the northwestern region of the western canada sedimentary basin wcsb were investigated for shale gas potential in the subsurface thermally mature strata of the besa river horn river muskwa and fort simpson formations attain thicknesses of more than 1 km 0 6 mi encompassing an area of approximately 125 000 km2 48 300 mi2 and represent an enormous potential gas resource total gas capacity estimates range between 60 and 600 bcf section of particular exploration interest are shales and mudrocks of the horn river formation including the laterally equivalent lower besa river mudrocks muskwa formation and upper besa river formation which yield total organic carbon toc contents of up to 5 7 wt fort simpson shales seldom have toc contents above 1 wt horn river and muskwa formations have excellent shale gas potential in a region between longitudes 122w and 123w and latitudes 59n and 60n national topographic system nts 94o08 to 94o15 in this area which covers an areal extent of 6250 km2 2404 mi2 average toc contents are higher 3 wt as determined by wire line log calibrations and have a stratal thickness of more than 200 m 656 ft gas capacities are estimated to be between 100 and 240 bcf section and possibly greater than 400 tcf gas in place a substantial percentage of the gas capacity is free gas caused by high reservoir temperatures and pressures muskwa shales have adsorbed gas capacities ranging between 0 3 and 0 5 cm3 g 9 6 16 scf t at reservoir temperatures of 60 80c 140 176f whereas besa river mudrocks and shales have low adsorbed gas capacities of less than 0 01 cm3 g 0 32 scf t liard basin region because reservoir temperatures exceed 130c 266f potential free gas capacities range from 1 2 to 9 5 cm3 g 38 4 to 304 scf t when total pore volumes 0 4 6 9 are saturated with gas the mineralogy has a major influence on total gas capacity carbonate rich samples indicative of adjacent carbonate platform and embayment successions commonly have lower organic carbon content and porosity and corresponding lower gas capacity 1 toc and 1 porosity seaward of the carbonate slave point edge muskwa and lower besa river mudrocks can be both silica and toc rich up to 92 quartz and 5 wt toc and most favorable for shale gas reservoir exploration because of possible fracture enhancement of the brittle organic and siliceous rich facies however an inverse relation between silica and porosity in some regions implies that zones with the best propensity for fracture completion may not provide optimal gas capacity and a balance between favorable reservoir characteristics needs to be sought

a theoretical analysis of interflow of water through surface soil horizons with implications for movement of chemicals in field runoff steady interflow of water in the near surface saturated soil horizons which are the important nonpoint sources of applied agricultural chemicals appearing in field runoff is investigated theoretically analytical solutions are obtained for some relevant cases of interflow in a sloping layered soil having a subsoil of lower permeability analysis is made for the effect of the relative permeability of the subsoil and of the depth of the subsoil above an impermeable base varying from zero to infinity in relation to different ratios of slope length to soil profile depth solutions and analyses are also extended to a case where flow through the topsoil is saturated and steady but where the subsoil is still accepting a constant downward flux of water uniformly over all its area the solutions are for a rectangularly bounded tilted flow medium but for long slopes the details of the flow medium boundaries at the top and bottom ends should have negligible effects on overall flow the results show that the interflow through each horizon of a layered soil profile can be approximated by a one dimensional darcian flow parallel to the slope if the ratio of slope length to soil profile depth is greater than about 6 to 10 this extends the finding reported earlier in the literature for a uniform soil for an extreme case of a sloping soil with a semi infinitely deep subsoil on an impermeable base the interflow through the topsoil if it is highly conductive compared to the subsoil can still be treated as a one dimensional flow for such cases the movement of soil chemicals with interflow can be described as a one dimensional miscible displacement process a uniformly constant downward flux of water into the subsoil decreases interflow through the topsoil the extent of the decrease depends upon the land slope and the relative conductivity of the subsoil of even greater significance for chemical transport is the finding that the cross section of the topsoil through which the interflow traverses and picks up its chemical load is drastically reduced by downward leakage even when the subsoil conductivity is two orders of magnitude smaller than that of the topsoil a simplified prediction of this region of interflow is deduced from the results by representing this wedge shaped area by an equivalent rectangle the chemical movement for a first order estimation in field application may still be approximated as a one dimensional displacement

influence of chemical properties on ch4 adsorption capacity of anthracite derived from southern sichuan basin china abstract this study aimed to determine the effects of high rank coal chemical properties on ch4 adsorption capacity a total of 24 core samples of anthracite from 11 coalbed methane wells in southern sichuan basin china were examined systemically using maceral analysis proximate and ultimate analyses total sulfur content test and ch4 isotherm adsorption experiment results show that vitrinite group macerals are the most abundant maceral group followed by inertinite and inorganic mineral matter of these coals vitrinite and inertinite rich coals have the similar average langmuir volume under dry ash free basis vldaf and no positive or negative correlation was found between vldaf and vitrinite and inertinite content in addition there is a weakly negative relationship between inorganic mineral matter and ch4 adsorption capacity effects of coal elements by ultimate analysis such as c element and the atomic ratios of h c o c and n c on ch4 adsorption capacity were studied ch4 adsorption capacity has positive correlation with c element content h c atomic ratio and n c atomic ratio respectively but negative with o c atomic ratio effects of four proximate analysis parameters moisture ash fixed carbon and volatile matter content on ch4 adsorption capacity were also studied moisture ash and volatile matter content negatively affect ch4 adsorption respectively and fixed carbon content has exactly the opposite effect principle component regression analyses for the set of elements and proximate analysis parameters show that c o ash and fixed carbon content are the important influence factors on ch4 adsorption capacity

investigations on the methane sorption capacity of marine shales from sichuan basin china abstract high pressure methane sorption isotherms measured at 30 50 and 80 c and pressure up to 20 mpa were measured on lower silurian marine shales from sichuan basin of china the effect of total organic carbon content temperature thermal maturity mineral composition and pore structure on methane sorption capacity has been investigated a linear combination approach has been developed to predict the langmuir sorption capacity of shales based on the mass fractions of their organic and inorganic components this information can be used to estimate the in situ sorption capacity of shale layers as a function of burial depth formation pressure and temperature and composition methane sorption capacity of the dry shales shows a positive relationship with toc and specific surface area the langmuir pressure decreases with increasing maturity but the toc normalized langmuir sorption capacity of over mature shales also decreases with increasing thermal maturity this may be related to the carbonization of highly over mature organic matter for the samples investigated approximately 16 3 46 7 average 28 6 of the methane sorption can be attributed to clay minerals and 46 5 81 5 to average 67 6 organic matter in these shales respectively using the linear combination approach the calculated langmuir sorption capacity function matches the measured values reasonably methane sorption capacity computed as a function of depth for a mean hydrostatic pressure gradient of 0 01 mpa m and a geothermal gradient of 0 03 c m shows a rapid increase and reaches a maximum between 900 and 1800 m followed by a slow decrease with increasing depth at shallow burial depths 900 1800 m sorption capacity is controlled by the geothermal gradient higher geothermal gradients result in a steeper decline of sorption capacity

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

effects of igneous intrusions on coal petrology pore fracture and coalbed methane characteristics in hongyang handan and huaibei coalfields north china article i nfo the effects of igneous intrusions have proved to be important for the exploration and development of coalbed methane in many coal basins however the studies of the influences of localized intrusions on coalbed meth ane reservoirs are still insufficient in the context of five typical dike sill intrusion patterns i e dike cut through dike cut in floor intrusion by sill roof intrusion by sill and dual intrusions of roof and floor by sills this study investigates the changes of coal organic composition and pores fractures resulting from igneous intrusions the influences of igneous intrusions on coal composition mainly include the decrease of vitrinites especially telocollinite and the increase of inertinites contents as well as the formation of secondary devolatilization vacuoles and of exogenous desiccation microfractures the vacuoles have size of 0 1 10 m and the microfractures are commonly developed with a wide space and a significantly short length the microfractures typically have irregular dendritic filamentous and turtleback textures and densi ties of hundreds per 9 cm 2 the influences of igneous intrusions on coal pores and fractures vary significantly depending on the intrusion patterns the coal ranks after the intrusion and the nature of the adjacent forma tion surrounding the intrusion for the coals with a vrr 4 2 the intrusion significantly reduced the coal pore development for the coals with a vrr from 2 1 4 2 the development of the coal pores improved with decreasing distance to the contact for the coals with a vrr b2 1 the intrusion resulted in a slight improvement of the coal pore development a possible explanation for the increasing gas content near the intrusion is that the secondary vacuoles and microfractures induced an increase in the gas storage capacity and in the permeability of the coal reservoir the detailed intrusion patterns of sills and dikes contribute to the formations of the coalbed methane accumulation in coal seams and to the coal generated gas accumula tion in the reservoir of the highly permeable surrounding rocks

the role of the residual bitumen in the gas storage capacity of mature lacustrine shale a case study of the triassic yanchang shale ordos basin china abstract the role of the residual bitumen in the shale gas storage capacity is investigated for potential terrestrial shale gas reservoirs in the yanchang area southern ordos basin china the upper triassic organic rich yanchang shales comprise of thermally mature chang 7 shale average toc 5 12 wt type i ii1 kerogen tmax 443 458 c ro 0 83 1 02 and relatively mature chang 9 shale average toc 4 40 wt type i ii1 kerogen tmax 443 476 c ro 0 88 1 10 the mineralogy of yanchang shales is dominated by clay minerals average 48 85 and quarts average 31 7 a series of low pressure nitrogen adsorption desorption and high pressure methane sorption experiments were conducted on pretreated fresh drilling cores including three groups of core samples one original group one group extracted by dichloromethane and the other group extracted by trichloromethane selected from yanchang shales to demonstrate the role of the residual bitumen in the shale gas potential low pressure nitrogen sorption method was used to elucidate the effect of the residual bitumen on the pore structure of yanchang shales the results show that the specific surface area and pore volume and pore surface area of shale samples after the extraction greatly increase and their growth was closely related with pores of 30 nm and

sorption of methane on lignite from polish deposits abstract coal samples from miocene lignite deposits ortholignite ece un 2002 in belchatow adamow konin and turow poland were analyzed to determine the relationships between coal properties and gas capacity investigations presented here addressed the occurrence of methane sorbet in lignite deposits within poland s largest penetrated lignite deposits e g belchatow adamow turow and konin lignite samples collected from surface mines were detritic coal with variable contents of xylites the highest level of xylites up to 25 vol was found in carbon samples taken from the belchatow deposit samples from other mines contained no more than 10 vol xylites petrographic compositions were dominated by huminite group macerals 73 88 vol with atrinite densinite and texto ulminite a porous form of ulminite inertinite groups were less important components 4 8 vol isotherms were determined for methane sorption at 298 k with test pressure ranges below 1 2 mpa at a pressure of 1 0 mpa the largest gas capacity of approximately 1 7 dm3 stp kg was found in the sample from belchatow this result may have been attributable to differences in the porosity of the samples the porosity of the sample from belchatow was twice as high as the porosities of the other coal samples this variation in porosity resulted from the lithologic and maceral composition of the coal sample that contained substantial quantities of porous textinite and texto ulminite the thermal sorption equation was used to determine the limiting values of isosteric enthalpy of sorption which suggested weak interactions between methane and the lignite matrix the residual gas capacity of the tested samples was also determined all samples exhibited a high residual methane bearing capacity which may not only cause methane to be released from coal at a pressure of 1 bar but also may pose a gas risk during mining operations

experimental study on the petrophysical variation of different rank coals with microwave treatment to maximize coalbed methane recovery the reservoir is often stimulated because of its low permeability an exploratory study on improving coal porosity and permeability by microwave treatment was proposed pore size distribution of four unconstrained coals lignite subbituminous bituminous and anthracite before and after microwave treatment were evaluated using the nuclear magnetic resonance with continuous exposure to microwaves the pore size distribution of coals especially the lignite coal extends and the pore volume and connectivity increase in addition coal porosity and permeability evaluated based on the schlumberger doll research model increase by 33 72 and 73 181 respectively the mechanism was revealed by combining p wave tests thermal imaging and x ray computed tomography scanner the moisture and minerals bounded in pores are selectively heated and then detached and as a result the pore structure is opened continued exposure to microwaves rapidly converts the mobilized moisture into super heated steam under the steam pressure pores and fractures generally expand borrowing from microwave assist oil recovery we presented a conceptual design of a cbm extraction borehole with microwave irradiation

historical variations in the isotopic composition of atmospheric zinc deposition from a zinc smelter abstract in order to test the usefulness of stable zinc isotopes as an atmospheric source tracer we analyzed the zinc isotopic composition of two sediment cores taken at 1 km distance of the former zinc smelter in lommel belgium the peat bog lake sediments accumulate mainly atmospheric particles have high organic matter contents 12 60 wt are anoxic and highly contaminated with heavy metals up to 4 7 wt zn and 1 1 wt pb with a sulfide mineralogical control on mobility down core variations in 66 zn relative to the jmc 3 0749l standard were small ranging from 0 07 to 0 39 but are nevertheless eight times the external reproducibility of 0 04 good agreement was found between the two cores and despite 30 zn mobilization to deeper layers no evidence of associated diagenetic zn isotope fractionation was found sediments deposited in the early 20th century have 66 zn of 0 30 0 05 2sd n 5 and a shift takes place between 1945 and 1950 to 66 zn values of 0 14 0 09 2sd n 7 in the 2nd half of the century in order to understand this shift in 66 zn we analyzed 32 ore grade sphalerite zns samples from african australian and european origin together with 29 published 66 zn values for ore grade zns we find remarkably homogeneous isotopic compositions which when averaged for mining location gives 66 zn of 0 16 0 20 2sd n 10 mines n 61 analyses early 20th century zn deposition with 66 zn of 0 30 is significantly different p 66 zn of 0 16 we suggest that this reflects the presence of an atmospheric smelting residue slag component enriched in the heavy zn isotopes due to rayleigh type fractionation during zn refining

the diavik waste rock project initial geochemical response from a low sulfide waste rock pile abstract three large scale experimental waste rock piles test piles were constructed and instrumented at the diavik diamond mine in the northwest territories canada as part of an integrated field and laboratory study to measure and compare physical and geochemical characteristics of experimental low sulfide waste rock piles at various scales this paper describes the geochemical response during the first season from a test pile containing 0 053 wt s bulk drainage chemistry was measured at two sampling points for ph eh alkalinity dissolved cations and anions and nutrients the geochemical equilibrium model minteqa2 was used to interpret potential mineral solubility controls on water chemistry the geochemical response characterizes the initial flushing response of blasting residues and oxidation products derived from sulfides in waste rock exposed to the atmosphere for less than 1 year sulfate concentrations reached 2000 mg l 1 when ambient temperatures were 10 c and decreased as ambient temperatures declined to 1 as total caco 3 suggesting all available alkalinity is consumed by acid neutralizing reactions concentrations of al and fe were 1 respectively trends of ph and alkalinity and the calculated saturation indices for al and fe oxy hydroxides suggest that dissolution of al and fe oxy hydroxide phases buffers the ph the effluent water showed increased concentrations of dissolved mn 1 ni 1 co 1 zn 1 cd 1 and cu 1 as ambient temperatures increased manganese is released by aluminosilicate weathering ni and co by pyrrhotite fe 1 x s oxidation zn and cd by sphalerite oxidation and cu by chalcopyrite cufes 2 oxidation no dissolved metals appear to have discrete secondary mineral controls changes in so 4 ph and metal concentrations indicate sulfide oxidation is occurring and effluent concentrations are influenced by ambient temperatures and possibly increasing flow path lengths that transport reaction products from previously unflushed waste rock

the zinc stable isotope signature of waste rock drainage in the canadian permafrost region leachate from a well instrumented experimental scale waste rock pile test pile at the diavik diamond mine northwest territories was monitored the well characterized waste rock consists of granite pegmatitic granite and biotite schist with an average total sulfur and carbonate carbon concentration of 0 053 and 0 027 wt respectively the leachate emerging from the southern basal drain of the waste rock pile has been monitored since 2007 the zinc stable isotope footprint was characterized alongside standard monitoring parameters during two field seasons may to november 2011 and 2012 the ph ranged between 4 3 and 6 8 and carbonate alkalinity was low or undetectable 35 mg l 1 caco3 the ph was governed by the oxidation of sulfide minerals and the dissolution of primary carbonate minerals and secondary al and fe oxyhydroxysulfates and hydroxides dissolved al and fe concentrations averaged 6 78 mg l 1 and 175 g l 1 respectively the main processes controlling zn concentrations in the range of 0 4 and 4 7 mg l 1 average 2 2 mg l 1 were the oxidative dissolution of sphalerite zns and the attenuation by secondary fe and al hydroxides zinc isotopes were fractionated mass dependently zinc isotope ratios ranging between 0 16 and 0 18 average 0 05 n 43 were consistent with values reported for sphalerite from other deposits the deviations in isotope ratios 0 36 were significant in comparison to analytical uncertainties 0 06 zinc isotope ratios and concentrations were largely uncorrelated suggesting that the processes affecting zn mobility had little or no impact on the zn isotope signature these data suggest that the zn isotope ratios of the waste rock leachate may be used as a fingerprint to track anthropogenic mine derived zn sources in an environment under fluctuating ph temperature and ionic strength

coal reservoir characteristics and coalbed methane resource assessment in huainan and huaibei coalfields southern north china abstract the huaibei and huainan coalfields in southern north china contain abundant coalbed methane cbm resources 1 1 10 12 m 3 net accumulated thicknesses of all minable coal seams are 18 32 m in huainan and 8 18 m in huaibei coalfields coal rank in the huainan coalfield high volatile a and b bituminous r o 0 65 0 85 is generally controlled by geothermal metamorphism in comparison coal rank in the huaibei coalfield varies from high volatile a bituminous to semi anthracites 0 8 to 2 8 r o and is controlled by the influence of the cretaceous yanshanian magmatic metamorphism in both coalfields coal reservoirs have low permeability values of 0 0013 0 224 md and porosity of 0 9 10 9 pores in coals are dominated by those with diameter 2 in both coalfields the abundance of microfractures in coals is related to the coal structures commonly more abundant in sheared coals 200 per 9 cm 2 than in the normally structured coals 2 the in place gas content is generally 8 16 m 3 t in huaibei and 10 30 m 3 t in huainan coalfields these data yield an estimated in place cbm resource of 375 247 10 9 m 3 for the huaibei and 722 677 10 9 m 3 for the huainan coalfields based on the cbm resource investigation and reservoir evaluation the most prospective target areas for cbm production are evaluated which include the nanping taoyuan mines of the southern suxian deep coal district and zhuxianzhuang and luling mines in eastern suxian area of the huaibei coalfield and the area around the panji 2 mine in panji xieqiao coal mining districts in the huainan coalfield

fractionation of cu fe and zn isotopes during the oxidative weathering of sulfide rich rocks abstract we measured the fe cu and zn isotopic compositions of the fluids generated during leaching experiments with pyrite chalcopyrite and sphalerite rich rocks and with a sphalerite mineral separate our study demonstrates that the oxidative weathering of sulfide rich rocks can produce substantial variations in fe 1 75 to 1 0 56 fe solution pyrite rock and cu 0 0 to 2 0 65 cu solution chalcopyrite rock isotopes and small variations in zn isotopes 0 0 to 0 2 66 zn solution sphalerite in the fluid phase relative to the rock for the fe and cu systems we suggest that isotopic fractionation is caused by electron exchange driven e g fe ii fe iii and cu i cu ii redox reactions at the surfaces of the sulfide minerals that occur during air and aqueous chemical reactions under acidic conditions these reactions tend to enrich the fluid phase in the heavier fe and cu isotopes however under circumneutral ph conditions the fe isotopic composition in solution was controlled by the precipitation of fe iii oxide phases which enriched the solution in the lighter fe isotopes this investigation provides a preliminary framework for interpreting the impact of sulfide oxidation reactions on the distributions of stable fe cu and zn isotopes in natural waters

bituminous coal seams from underground mines in the zonguldak basin nw turkey insights from mineralogy coal petrography rock eval pyrolysis and meso and microporosity abstract the zonguldak basin contains the main bituminous coal reserves of turkey ca 1 4 gt and several coal seams are mined in underground coal mines within the basin this study focuses on coal petrography mineralogy rock eval pyrolysis and the meso and microporosity characteristics of the coal samples collected from several late carboniferous pennsylvanian bituminous coal seams in the basin forty channel samples were collected from various coal seams in underground mines at the armutcuk zonguldak and amasra coalfields in the zonguldak basin the studied coal samples have low total moisture contents avg 2 3 on as received basis low total s contents avg 0 5 on dry basis and relatively high ash yields avg 21 2 on dry basis the random vitrinite reflectance values 0 69 1 21 and gross calorific values avg 33 0 mj kg on dry ash free basis indicate that the coal samples are of high volatile c bituminous to medium volatile bituminous coal minerals identified by xrd in bulk coal samples are clay minerals mainly kaolinite and rarely illite and chlorite quartz and carbonates calcite dolomite and siderite in a few samples pyrite and feldspar were also identified the sem edx analyses performed on the carbon coated polished blocks imply that the carbonate minerals are mainly epigenetic whereas the silicate minerals are generally syngenetic in origin the results of low pressure n2 adsorption analysis indicate that the bet surface areas 1 1 5 5 m2 g and mesopore volumes 0 003 0 011 cm3 g vary within a wide range the results of the low pressure co2 adsorption analyses show that micropores are abundant in the coal samples however the bet surface areas 10 41 78 11 m2 g and micropore volumes 0 010 0 049 cm3 g vary widely among the three coal mines and different coal seams our results suggest that variations in the mesopore characteristics are mainly controlled by mineral matter while microporosity is controlled by a combination of organic matter maceral compositions and coal rank of the studied coal seams

determination of molybdenum isotope fractionation by double spike multicollector inductively coupled plasma mass spectrometry 1 molybdenum isotopic compositions are precisely determined by mc icp ms measurements using a mo double spike the double spike is added prior to chemical purification so that laboratory and instrumental mass fractionations are separated from natural mass dependent fractionation fractionation is determined on four mo mass ratios providing an internal consistency check the external standard reproducibility is at 0 06 per mil on the 98mo 95mo ratio 2 standard deviation using a normal microconcentric nebuliser with a cyclonic spray chamber the minimum quantity of mo is 1 g for high precision results a hydrothermal molybdenite shows fractionation of 0 3 per mil on the 98mo 95mo ratio relative to our standard johnson matthey 1000 g ml 0 3 icp standard solution lot 602332b fine grained sediments show fractionation of 0 1 and 0 3 per mil on the 98mo 95mo ratio the observed mo isotope fractionation is small but resolvable with the presented high resolution technique

study on coalbed methane accumulation characteristics and favorable areas in the binchang area southwestern ordos basin china article the binchang area of southwestern ordos basin is one of the most promising areas for low rank coalbed methane cbm in china this work investigates the jurassic yanan formation coal and cbm geology and accumulation characteristics of cbm in the southwestern ordos basin based on data from 46 wells and labo ratory measurements of 14 coal samples from 7 mines the results show that coal rank in the binchang area is mainly sub bituminous a and high volatile c bituminous 0 46 0 73 ro coals are dominated by inertinite 14 7 85 6 less abundant are vitrinite 8 5 77 7 and liptinite 1 5 15 2 minerals are found only in small amounts 0 4 8 3 permeability is between 0 04 and 25 3 md and porosity ranges from 2 4 to 20 1 most coal pores are less than 100 nm in diameter making them favorable for gas adsorption but unfavorable for gas permeability pore morphology is represented mainly by micro and mesopores with a well connected and ink bottle shaped narrow throat and wide body morphology these coals are charac terized by a high adsorption volume of more than 3 0 10 3

storm water hydrograph separation of run off from a mine tailings impoundment formed by thickened tailings discharge at kidd creek timmins ontario the kidd creek cu zn sulphide mine is located near timmins ontario mill tailings are thickened and deposited as a thickened slurry in a circular conical shaped pile with an area of approximately 1200 ha deposition of tailings as a thickened slurry results in a relatively uniform grain size distribution and hydraulic conductivity and a thick tension saturated zone above the water table the tailings are drained by numerous small ephemeral stream channels which have developed in a radial pattern during storms water from these streams collects in catchment ponds where it is held before treatment the contribution of tailings pore water to the run off is of interest because of the potential for discharge of pore water containing high concentrations of fe ii acidity metals and so4 to the stream hydraulic head measurements measurements of water table elevation and groundwater flow modelling were conducted to determine the mechanisms responsible for tailings pore water entering the surface streams chemical hydrograph separation of storm run off in one of these streams during three rainfall events using na and cl as conservative tracers indicates that the integrated tailings pore water fraction makes up between less than 1 and 20 of the total hydrograph this range is less than the maximum fraction of tailings pore water of 22 65 reported for run off from a conventional tailings deposit at this site preferential flow through permeable fractures may be the dominant mechanism causing discharge of tailings pore water to storm run off estimates of the mass of fe ii that discharges to the surface run off from the pore water range up to 2800 mg s 1 during a moderate intensity long duration rainfall event the greatest potential for discharge of significant masses of solutes derived from the pore water exists during long duration rainfall events when the water table rises to the surface over large areas of the tailings impoundment

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

the diavik waste rock project water flow through mine waste rock in a permafrost terrain abstract a field experiment is being carried out at the diavik diamond mine in northern canada to investigate the influence of unsaturated flow behavior on the quality of drainage from mine waste rock piles in a region of continuous permafrost this paper is part of a series describing processes affecting the weathering of waste rock and transport of reaction products at this site here the focus is on unsaturated water flow and its role in mass loading two 15 m high instrumented test piles have been built on 60 m by 50 m collection systems each consisting of lysimeters and a large impermeable high density polyethylene hdpe liner collection lysimeters are installed nearby to investigate infiltration in the upper 2 m of the waste rock porosity water retention curves and hydraulic conductivity functions are estimated from field measurements and for samples ranging in size from 200 cm3 to 16 m3 net infiltration in 2007 is estimated to have been 37 of the rainfall for mean annual rainfall conditions early season infiltration freezes and is remobilized as the waste rock thaws wetting fronts migrate at rates of 0 2 0 4 m d 1 in response to common rainfall events and up to 5 m d 1 in response to intense rainfall pore water and non reactive solutes travel at rates of

evaluation of geological features for deep coalbed methane reservoirs in the dacheng salient jizhong depression china abstract the dacheng salient of the northeast jizhong depression is one of the most promising areas for deep coalbed methane cbm development in china this work investigates the permo carboniferous c p taiyuan and shanxi formation coals and cbm geology and gas accumulation characteristics in the dacheng salient based on field data from 24 wells and laboratory measurements of eight coal samples and eight mudstone and sandstones from exploration well d1 1 the results show that the coal rank in the dacheng salient is a high volatile c bituminous coal to low volatile bituminous coal 0 54 1 85 r o controlled by the magmatism in the region the coals vary from 2 94 to 8 58 in porosity and 0 263 m 2 g to 2 6 m 2 g in bet surface area the in situ permeability is low normally less than 0 5 10 3 m 2 methane isothermal adsorption measurements of five coal samples reveal that their maximum adsorption capacity on an as received basis varies from 17 13 to 25 98 m 3 t with an apparent relationship with ash yield the roof and floor of coal seams are mainly mudstone with minor quantities of sandy mudstone and carbonate all have the ability to be suitable cap rocks with adequate sealing capacity and large breakthrough pressure the in place gas content range from 10 23 to 1 41 m 3 t with a decreasing trend from no 3 to no 6 coal seam group in the d1 1 well due to effects by the active ground water near the east jinghai dacheng fault however the gas content and the gas saturation increase with burial depth and ground water salinity and decrease with coal rank finally based on a comprehensive analysis of coal thickness gas content hydrogeology conditions roof floor and depth properties this study reveals that the best prospective target areas for cbm production are the south central parts of the dacheng salient at1200 1600 m in depth

geological controls and estimation algorithms of lacustrine shale gas adsorption capacity a case study of the triassic strata in the southeastern ordos basin china abstract high pressure methane adsorption experiments on a series of triassic lacustrine shale moisture equilibrated samples from the southeastern ordos basin china were conducted at pressure up to 20 mpa two of which were measured at 30 c 40 c 50 c 60 c and 70 c and seven were performed under reservoir temperature from 48 c to 62 c to investigate the effect of organic matter content maturity mineralogical compositions and reservoir conditions temperature and pressure on the methane sorption capacity the total organic carbon contents tocs range from 0 91 wt to 6 11 wt the thermal maturities as inferred from rock eval analysis range from low mature to high mature the minerals of the shale samples are dominated by clays 36 57 wt and quartz 19 44 wt for the entire shale samples the dominant clay minerals are mixed layer illite smectite with some illite and no smectite exists corresponding to a stage of late diagenesis the studied samples have n2 bet surface areas ranging between 1 47 and 9 21 m2 g and pore volumes of 0 013 0 034 cm3 g the methane sorption capacities of moisture equilibrated shale samples show a positive correlation with toc contents and bet surface areas no relationship was observed between the clay contents and methane sorption capacities indicating that clay minerals do not significantly contribute to methane sorption capacity in these organic shales the langmuir pressure pl increases exponentially with temperature and the langmuir volume vl decreases linearly with temperature a computational scheme has been developed to calculate the methane sorption capacity of shales as a function of toc content temperature and pressure based on langmuir sorption isotherm function using this algorithm methane sorption capacity of organic shales as function of depth can be obtained due to the predominating effect of pressure the methane sorption capacity increases with depth initially through a maximum and then decreases due to the influence of increasing temperature at a greater depth the maximum gas sorption capacity typically occurs at a depth range between 400 and 900 m with toc content increasing the maximum methane sorption capacities of organic shales and the corresponding depths increase

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

high heat flow effects on a coalbed methane reservoir east kalimantan borneo indonesia abstract the balikpapan formation miocene age in sangatta east kalimantan is thick 1500 m containing abundant coal seams that range in thickness from less than a meter to over 5 m coal seams are distributed throughout the section and may represent 5 to 7 of the total formation thickness measured gas contents range from

shale gas accumulation potential of the upper cretaceous qingshankou formation in the southeast songliao basin ne china abstract the purpose of this paper is to provide both quantitative and qualitative visual analyses of the nanometer scale pore systems of immature and early shales as well as to discuss the biogenic shale gas accumulation potential of the upper cretaceous section of the songliao basin to achieve these goals mineralogical compositions were determined using transmitted and reflected light petrography x ray diffractometry and scanning electron microscopy sem while the nanostructure morphology and pore size distributions psds were quantified using field emission scanning electron microscopy fe sem and low pressure nitrogen gas adsorption lp n2ga the results of these analyses indicate that nanometer scale pores are well developed in the immature and low maturity shale and that these shales contain many types of reservoir pores the mudstone layer of the qingshankou formation k2qn contains a high permeability characteristic and good rock fracturing conditions while it is also thick 9 m in thickness and rich in fine organic matter overall analysis of the entire formation using source rock and reservoir evaluations indicate that the first member of the qingshankou formation k2qn1 has a greater shale gas accumulation potential than the second and third members of the qingshankou formation k2qn2 3

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

hydrodynamic and stratigraphic controls for a large coalbed methane accumulation in ferron coals of east central utah abstract upper cretaceous coals within the ferron sandstone member of the mancos shale contain large volumes of coalbed methane coals at the northern end of the 80 mile long 129 km ferron trend have produced more than 200 billion cubic feet bcf 5663 10 6 m 3 of coalbed methane with daily production of 260 million cubic feet per day mmcfd 7 36 10 6 m 3 day from 470 wells during november 2000 core data from exploratory wells drilled along trend to the south indicate that the gas content of the coals decreases dramatically from north to south even though the rank and maturity of the coals decreases only slightly the area with lowest gas content correlates with the outcrop of the ferron coals hydrodynamic studies have shown that the ferron coals are aquifers that are recharged from the wasatch plateau to the west regional mapping indicates that the productive fields are large stratigraphic traps where the coals pinchout updip into tight marine shales to the east much of the produced gas is secondary biogenic gas and migrated thermogenic gas that has moved from the wasatch plateau and south margin of the uinta basin respectively further south near the town of emery coals are present at the surface but most of the gas has been flushed out of the coals due to reduction of reservoir pressure and active water flow from the west therefore the entire ferron trend probably contained tremendous volumes of stratigraphically trapped coalbed methane before uplift and erosion exposed the southern coals to the atmosphere

possible controls of hydrogeological and stress regimes on the producibility of coalbed methane in upper cretaceous tertiary strata of the alberta basin canada the coalbed methane potential and producibility of any coal bearing strata are strongly affected by the hydrogeological regime of formation waters and by coal permeability which in turn depends on the effective stress regime of the coals peat that accumulated in the alberta basin during the late cretaceous and early tertiary led to the formation of coal deposits that may contain significant coalbed methane resources the flow of formation waters plays an important role in the maintenance and producibility of this resource the present day flow is driven by gravity topography and erosional rebound and is controlled by rock permeability and the presence of gas saturated sandstones the estimated gas in place in the tertiary upper cretaceous coals decreases significantly with stratigraphic age ranging between less than 2 bcf mi2 in the lower coal zones and 12 bcf mi2 in the uppermost coals the gas content especially of the deeper coals is lower than would be expected for the corresponding coal rank and burial depth most likely because the underpressuring has caused the release of gas from the coals and accumulation in adjacent sands the shallow coals although of low rank may contain important amounts of late stage biogenic methane the salinity of formation water in shallow coal seams where the flow is driven by topography is low generally less than 1500 mg l although in places it reaches 3000 5000 mg l the salinity of formation water in the deeper underpressured strata in the west central part of the basin is significantly higher reaching 18 000 mg l this affects treatment and or disposal strategies with regard to the water produced concurrent to coalbed methane the producibility of this resource depends on coal permeability which decreases west southwestward with increasing burial depth from the order of several darcys in the shallow zones to millidarcys in the deep zones the minimum effective stress which affects coal permeability by closing fractures increases west southwestward from zero at the erosional edge of these strata to approximately 20 mpa near the rocky mountain deformation front fractures including those in coal seams will generally be vertical and will propagate on a southwest northeast axis along the direction of the maximum horizontal stress in a direction generally perpendicular to the rocky mountain deformation front considering the hydrogeological and stress regimes in conjunction with estimations of the gas content in coals the region with probably good coalbed methane potential and producibility are the ardley coal zone in the scollard formation and maybe to a lesser extent the coal zones of the stratigraphically deeper edmonton and belly river groups along their respective subcrop in central and southern alberta the deep edmonton and belly river strata in western and central alberta have most likely a reduced coalbed methane potential as a result of lower gas content and of low permeability these regional considerations need to be applied against local studies of coal thickness rank permeability and gas content to identify the best targets for coalbed methane exploration and production

preliminary evaluation of the coalbed methane production potential and its geological controls in the weibei coalfield southeastern ordos basin china article i nfo the coalbed methane cbm geology resource and production potential in the weibei coalfield southeastern ordos basin are studied based on geological surveys and laboratory measurements the results showed that coal rank varies both laterally and vertically and changes from volatile bituminous coals in the margin to anthracites towards the basin 1 6 2 5 ro coals are composed of 60 85 vitrinite 15 40 inertinite and a trace amount of minerals methane isothermal adsorption measurements of 20 coal samples revealed that the maximum adsorption capacity on a dry and ash free basis of coals which are affected by coal rank coal maceral coal lithotype and especially to the moisture content varies from 13 91 to 29 54 m 3 t estimated gas contents range from 0 to 15 m

on the effects of petrographic composition on coalbed methane sorption abstract the effect of petrographic composition on the methane sorption capacity has been determined for a suite of coals and organic rich shales subbituminous and bituminous coals were separated into bright and dull lithotypes by hand picking the methane sorption capacities range between 0 5 and 23 9 cm 3 g at a pressure of 6 mpa the low volatile bituminous canmore coal and the anthracite sample have the highest capacities with the natural coke having the lowest for low rank coals there is no significant difference between bright and dull samples except for one coal with the dull sample having a greater sorption capacity than its bright equivalent for higher rank coals the bright samples have a greater methane capacity than the dull samples and the difference between sample pairs increases with rank the boghead coal samples have the highest sorption capacities in the liptinite rich coals suite and are higher than subbituminous to medium volatile bituminous samples pore size distribution indicates that methane is held as solution gas in liptinite rich coals and by physical sorption in micropores in liptinite poor coals these contrasting processes illustrate that liptinite rich samples need to be independently assessed the positive relationship between reactive inertinite content and methane sorption capacity occurs within the subbituminous to medium volatile bituminous coals because the reactive inertinite is structurally similar to vitrinite and have a higher microporosity than non reactive inertinite reactivity of inertinite should be assessed in cbm studies of dull coals to provide a better understanding of petrographic composition effects on methane capacity

zinc isotope and transition element dynamics accompanying hydrozincite biomineralization in the rio naracauli sardinia italy abstract the rio naracauli in sw sardinia drains part of the ingurtosu zn pb mining district and contains extreme concentrations of dissolved zn at near neutral ph in the upper reaches of the stream ph alkalinity and zn concentrations are such that hydrozincite zn 5 co 3 2 oh 6 precipitates in a biologically mediated process facilitated by a microalga chlorella sp and a cyanobacterium scytonema sp values of 66 zn in water and solid samples ranged from 0 35 to 0 5 relative to the jmc 3 0749 lyon standard and closely follow a mass dependent fractionation line two composite samples of sphalerite the primary ore mineral in the ingurtosu deposits had an average 66 zn of 0 15 similar to sphalerite measured elsewhere in hydrothermal mineral deposits zinc isotope measurements of the stream water and the hydrozincite forming in the stream show a consistent preference for the heavy isotope 66 zn in the hydrozincite relative to 64 zn synthetic hydrozincites produced without added bacteria have 66 zn identical to the dissolved zn thus suggesting a biologically mediated mineralization process in rio naracauli the average fractionation hdz water is 0 35 the magnitude of which is consistent with other studies and suggests an extracellular mechanism of the biomineralization process zinc concentration and dissolved 66 zn steadily decrease in the reach of the stream where the biomineralization occurs the biomineralization process also leads to the sequestration of pb cu and ni in the hydrozincite lattice and the coeval precipitation of an amorphous cdco 3 solid prompting the suggestion that if optimized the biomineralization process might represent a feasible passive remediation strategy for streams with high zn and other metals and with near neutral ph

characterization of gas shale pore systems by porosimetry pycnometry surface area and field emission scanning electron microscopy transmission electron microscopy image analyses examples from the barnett woodford haynesville marcellus and doig units the nanometer scaled pore systems of gas shale reservoirs were investigated from the barnett marcellus woodford and haynesville gas shales in the united states and the doig formation of northeastern british columbia canada the purpose of this article is to provide awareness of the nature and variability in pore structures within gas shales and not to provide a representative evaluation on the previously mentioned north american reservoirs to understand the pore system of these rocks the total porosity pore size distribution surface area organic geochemistry mineralogy and image analyses by electron microscopy were performed total porosity from helium pycnometry ranges between 2 5 and 6 6 total organic carbon content ranges between 0 7 and 6 8 wt and vitrinite reflectance measured between 1 45 and 2 37 the gas shales in the united states are clay and quartz rich with the doig formation samples being quartz and carbonate rich and clay poor higher porosity samples have higher values because of a greater abundance of mesopores compared with lower porosity samples with decreasing total porosity micropore volumes relatively increase whereas the sum of mesopores and macropore volumes decrease focused ion beam milling field emission scanning electron microscopy and transmission electron microscopy provide high resolution 5 nm images of pore distribution and geometries image analysis provides a visual appreciation of pore systems in gas shale reservoirs but is not a statistically valid method to evaluate gas shale reservoirs macropores and mesopores are observed as either intergranular porosity or are confined to kerogen rich aggregates and show no preferred orientation or align parallel with the laminae of the shale networks of mesopores are observed to connect with the larger macropores within the kerogen rich aggregates

zinc isotope variation in hydrothermal systems preliminary evidence from the irish midlands ore field little is known about the range or controls on the zinc isotope composition of terrestrial materials and no systematic studies have been carried out on ore forming systems we have obtained zinc isotope data from 19 sphalerite samples formed over a range of well constrained precipitation conditions from the irish zn pb ore field the results reveal variation in 66zn where 66zn 66zn 64zn sample 66zn 64zn standard 1 1000 from 0 17 to 1 33 per mil relative to the lyon jmc 3 0749l zinc standard this variation is significant compared to the external reproducibility 0 12 2 and the data show very good mass dependency with 67zn and 68zn values thus natural variations in the zinc isotope composition of these ore minerals can be resolved our results span the entire range of 66zn values measured on terrestrial geologic samples to date the data suggest that variations in the primary source rock composition or precipitation temperature are unlikely to be important controls on the zinc isotope composition of sphalerite in the ore field we suggest that the variation is most likely due to a kinetic fractionation involving the preferential incorporation of light zinc isotopes in sphalerite precipitated rapidly under disequilibrium conditions however we cannot rule out the possibility of mixing of zinc derived from two isotopically distinct sources the significant variation in zinc isotope compositions we have observed in the irish ore field confirms that such fractionations can provide new insights into mineralizing processes in the earth s crust

a preliminary study on the pore characterization of lower silurian black shales in the chuandong thrust fold belt southwestern china using low pressure n2 adsorption and fe sem methods although lower silurian black shales within and around the sichuan basin have received renewed attention during the past few years because of their potential prospectivity for shale gas studies associated with shale gas reservoir evaluation are still rare in this study eight black shale core samples were collected from a well drilled recently in the chuandong thrust fold belt southwestern china and their geochemistry and pore structures were investigated using low pressure n2 adsorption analysis and field emission scanning electron microscopy fe sem observations the results show that the black shales have total organic carbon toc values ranging from 1 01 to 3 98 and their equivalent vitrinite reflectance values are in the range of 2 84 3 05 both mineral matrix and organic matter pores are well developed with pore sizes ranging from several to several hundred nanometers the total porosity for the eight samples ranges from 2 60 to 4 74 and the percentages of organic matter pores are estimated to be in the range of 31 62 the total surface area ranges from 5 06 m2 g to 19 32 m2 g and the micropore 2 nm surface area estimated by the t plot method ranges from 3 13 m2 g to 9 27 m2 g the toc values have positive relationships with the total porosity total surface area and the micropore 2 nm volume and surface area indicating toc may be an effective parameter for shale gas reservoir evaluation in the studied area

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

effect of subsoil conductivity and thickness on interflow pathways rates and source areas for chemicals in a sloping layered soil with seepage face abstract the effects of relative hydraulic conductivities and thicknesses of topsoil and subsoil layers and leakage rate of a compact base material on the saturated steady water flow through a sloping soil to an outflow face interflow were investigated theoretically the water was assumed to be supplied from the surface at a rate adequate to keep the entire soil saturated simplified descriptions of the interflow characteristics were sought wherever possible a gram schmidt orthonormalization procedure of w l powers d kirkham and g snowden provided a potential theory solution of the problem even though the outflow seepage face existed over two soil layers as reported earlier by the present authors for a nonlayered soil two regions of water entry and flow could be distinguished when the base material was not leaky 1 flow in the main body of soil region 1 and 2 additional infiltration and flow near the seepage face region 2 for a slope length soil depth ratio of 20 or greater the flow in region 1 could be approximated as a one dimensional flow downslope in each soil layer the length of slope that contributed to flow in region 2 was linearly related to the ratio of the hydraulic conductivity of the subsoil to that of the topsoil a subsoil of higher conductivity than that of the topsoil increased several fold the rate of infiltration and interflow and the soil both topsoil and subsoil volume that was traversed by interflow near the seepage face it also increased the area and rates of water entry and flow through the topsoil near the upper end of the slope a significant finding of this analysis is that the transport of topsoil chemicals to field runoff will be speeded up from certain now predictable portions of the slope length when the underlying base material was leaky some water entering the soil surface seeped into the base material and the soil volume traversed by the interflow was greatly reduced amounts of chemicals carried to the outflow face would also be reduced there were several situations of base leakage rates soil conductivities and thicknesses considered for leakage rates of practical interest the source areas and the soil volume traversed by the interflow could be predicted adequately by a simple procedure the total rates of water interflow in both the nonleaky and leaky base cases could be predicted adequately from known reference values of a nonlayered soil by using a weighted average hydraulic conductivity of the layered profile however for prediction of chemicals transported with interflow knowledge of the flow directions and rate variation along the slope length will be required

determining provenance of marine metal pollution in french bivalves using cd zn and pb isotopes abstract cadmium zn and pb isotopic compositions mc icp ms and elemental concentrations hr icp ms have been used to distinguish between natural and anthropogenic sources of these metals in bivalves collected from the coastlines of france english channel atlantic and mediterranean coasts the cd isotopic signatures 114cd 1 08 to 0 52 exhibited by bivalves from the coastlines of france excluding those from ne france are within the range of those exhibited by bivalves from the usa east coast 114cd 1 20 to 0 54 this indicates the high prevalence of industry as well as the low natural contributions of cd from north atlantic waters in both regions thus the significance of anthropogenic cd sources is similar these significant anthropogenic contributions are identified for bivalves with a large range in tissue cd concentrations importantly french bivalves from the gironde estuary and marennes oleron basin regions of historic and modern importance for oyster farming respectively exhibited the highest cd levels of the study their cd isotopic signatures indicate historical smelting emissions remain the primary cd source despite the cessation of local smelting activities in 1986 and subsequent remedial efforts no significant variability is observed in the 66zn values of the french bivalves 0 53 with the exception of the much heavier compositions exhibited by oysters from the polluted gironde estuary 1 19 1 27 lead isotopes do not fractionate during processing like cd and zn they can therefore be used to identify emissions from industrial processes and the consumption of unleaded gasoline and diesel fuel as metal sources to french bivalves cadmium and zn isotopes are successfully used here as tracers of anthropogenic processing emissions and are combined with pb isotope fingerprinting techniques to identify metal sources

methanogenic pathways of coal bed gas in the powder river basin united states the geologic factor abstract coal bed gas of the tertiary fort union and wasatch formations in the powder river basin in wyoming and montana u s was interpreted as microbial in origin by previous studies based on limited data on the gas and water composition and isotopes associated with the coal beds to fully evaluate the microbial origin of the gas and mechanisms of methane generation additional data for 165 gas and water samples from 7 different coal bed methane bearing coal bed reservoirs were collected basinwide and correlated to the coal geology and stratigraphy the c1 c2 c3 ratio and vitrinite reflectance of coal and organic shale permitted differentiation between microbial gas and transitional thermogenic gas in the central part of the basin analyses of methane 13c and d carbon dioxide 13c and water d values indicate gas was generated primarily from microbial co2 reduction but with significant gas generated by microbial methyl type fermentation aceticlastic in some areas of the basin microbial co2 reduction occurs basinwide but is generally dominant in paleocene fort union formation coals in the central part of the basin whereas microbial methyl type fermentation is common along the northwest and east margins isotopically light methane 13c is distributed along the basin margins where d is also depleted indicating that both co2 reduction and methyl type fermentation pathways played major roles in gas generation but gas from the latter pathway overprinted gas from the former pathway more specifically along the northwest basin margin gas generation by methyl type fermentation may have been stimulated by late stage infiltration of groundwater recharge from clinker areas which flowed through highly fractured and faulted coal aquifers also groundwater recharge controlled a change in gas composition in the shallow eocene wasatch formation with the increase of nitrogen and decrease of methane composition of the coal bed gas other geologic factors such as burial thermal and maturation history lateral and vertical continuity and coalification of the coal beds also played a significant role in controlling methanogenic pathways and provided new perspectives on gas evolution and emplacement the early stage gas produced by co2 reduction has mixed with transitional thermogenic gas in the deeper central parts of the powder river basin to form old gas whereas along the basin margins the overprint of gas from methyl type fermentation represents new gas thus a clear understanding of these geologic factors is necessary to relate the microbiological biogeochemical and hydrological processes involved in the generation of coal bed gas

zn isotopes as tracers of anthropogenic pollution from zn ore smelters the riou mort lot river system article i nfo zn values up to 1 49 zn extraction yields for these samples were calculated using presumable conservative elements fe ca mg k na and mn and vary from 95 4 to 99 4 extraction yields are related to the intensity of zn isotopic fractionation different rayleigh isotope fractionation scenarios for zn refining yielded ore tailings ranging from 1 00012 to 1 00062 the 66 zn of the riou mort sediments downstream from

use of isotope ratios to assess sources of pb and zn dispersed in the environment during mining and ore processing within the orlovka spokoinoe mining site russia element concentrations element ratios and pb and zn isotope data are reported for different geologic samples barren and ore bearing granites and host rocks technogenic products ore concentrates and tailings and biologic samples lichens and birch leaves from the orlovka spokoinoe mining district eastern transbaikalia russia with the aim to trace the sources of pb and zn at a local level within the mining site lichens and birch leaves were used as receptors of contamination within the mining site pb zr and zn zr values indicated pb and zn enrichment relative to host rocks zn isotope data of 15 geologic and 11 lichen samples showed different zn isotopic signatures with the total range for the geologic suite of 0 4 to 1 2 and for lichens of 0 4 to 1 4 in 66zn relative to lyon jmc zn standard the source of isotopically heavy zn within the orlovka spokoinoe mining site could be potentially associated with long range atmospheric aerosols that also contributed pb to the studied mining site our results demonstrated that zn isotopes might be used as new tools for zn source assessment