pressure transients within mcs mesohighs and wake lows by animating enhanced coarse surface pressure observations of 12 1985 preliminary regional experiment for storm scale operational research meteorology pre storm mesoscale convective systems mcss the authors exposed 92 transitory highs and lows living within virtually all of the systems mesohighs and wake lows a quasi lagrangian feature following not material following analysis of the pressure fields produced five primary results first these transients with magnitudes of a few millibars horizontal dimensions of order 100 km and average lifetimes of about 2 h collectively composed spatial and temporal envelopes that contributed at least part of the total pressure field within mesohighs and wake lows transients did not apparently favor formation or dissipation in any location of the envelopes second as the mcss matured the difference between each complex s transitory highs mean pressure and transitory lows mean pressure increased in 78 of the conclusive cases apparently one frequent role of mcss is locally to magnify storm scale pressure gradients third transient paths reflect the frequent symmetric to asymmetric metamorphoses of the mcss fourth the temporal fluctuations of the numbers and apparent sizes of transients within a composite mcs partially support theories of mcs upscale evolution finally the composite s transient numbers and apparent sizes varied almost identically with time in a pattern that closely resembles the fluctuation of stratiform and convective volumetric rain rates of mcss

geological interpretation of gas content trends walloon subgroup eastern surat basin queensland australia abstract the middle jurassic walloon subgroup is a prolific low rank coal seam gas csg resource in the surat basin australia this study applied a regionally consistent stratigraphic framework model to open file gas desorption and coal property data from 69 cored csg wells to assess spatial trends in gas content and test the influence of large scale geological heterogeneity on present day gas distribution continued successful exploration and production and possible future microbial regeneration of the walloon csg resource require an improved understanding of the controls on gas content distribution across the core region of production in the eastern surat basin the walloon subgroup can be subdivided into upper juandah and lower taroom coal measures separated by a relatively coal barren and sandstone dominated unit tangalooma sandstone within these units lateral variation in coal character is high precluding a regionally agreed coal group or seam correlation while the total dataset shows a general increase in gas content dry ash free d a f with increasing depth as a function of hydrostatic pressure there is considerable scatter in the distribution within individual wells gas content follows one of three trends gas content either 1 increases 2 increases then decreases or 3 decreases with depth trend 2 parabolic wells predominate with the gas content maxima coinciding with the tangalooma sandstone regardless of depth as such gas content layering follows rather than cross cuts the stratigraphy in the majority of wells the change in gas content with depth between the different units and the wells was used to identify domains of different gas gradients which could relate to differing gas saturations and geological setting the well profiles and gas gradients were analysed against available open file coal quality data without strong correlation to rank or type parameters the majority of very high gas gradient values occur in coals within or above the tangalooma sandstone suggesting that it forms a regional scale barrier both to possible gas migration from underlying and higher rank coals and to meteoric and biogenic recharge from above increased ethane values in the upper taroom and tangalooma csg support this interpretation alternatively this distribution may be the result of alternating adsorption desorption cycles linked to burial and uplift the wells containing the highest mean gas gradients span a range of subtle rank and structural domains but generally occur in structural highs under topographic lows with hydrostatic head wells from smaller scale anticlines not associated with topographic surface lows mainly exhibit lower mean gas gradients the study significantly expands the number of published gas content trends and proposes several factors influencing their formation and geographical distribution the results form the basis for future targeted sampling to test for gas origins migration retention and biogenic recharge processes within the surat basin

global adjoint tomography first generation model we present the first generation global tomographic model constructed based on adjoint tomography an iterative full waveform inversion technique synthetic seismograms were calculated using gpu accelerated spectral element simulations of global seismic wave propagation accommodating effects due to 3d anelastic crust mantle structure topography bathymetry the ocean load ellipticity rotation and self gravitation frechet derivatives were calculated in 3d anelastic models based on an adjoint state method the simulations were performed on the cray xk7 named titan a computer with 18 688 gpu accelerators housed at oak ridge national laboratory the transversely isotropic global model is the result of 15 tomographic iterations which systematically reduced differences between observed and simulated three component seismograms our starting model combined 3d mantle model s362ani kustowski et al 2008 with 3d crustal model crust2 0 bassin et al 2000 we simultaneously inverted for structure in the crust and mantle thereby eliminating the need for widely used crustal corrections we used data from 253 earthquakes in the magnitude range 5 8 mw 7 0 for the first 12 iterations we combined 30 s body wave data with 60 s surface wave data the shortest period of the surface waves was gradually decreased and in the last three iterations we combined 17 s body waves with 45 s surface waves we started using 180 min long seismograms after the 12th iteration and assimilated minor and major arc body and surface waves the 15th iteration model features enhancements of well known slabs an enhanced image of the samoa tahiti plume as well as various other plumes and hotspots such as caroline galapagos yellowstone and erebus furthermore we see clear improvements in slab resolution along the hellenic and japan arcs as well as subduction along the east of scotia plate which does not exist in the starting model point spread function tests demonstrate that we are approaching the resolution of continental scale studies in some areas for example underneath yellowstone this is a consequence of our multi scale smoothing strategy in which we define our smoothing operator as a function of the approximate hessian kernel thereby smoothing gradients less wherever we have good ray coverage such as underneath north america

a survey of the microbial populations in some australian coalbed methane reservoirs isotopic data indicate that coalbed methane cbm in many australian reservoirs comprise secondary biogenic gas however little is known of the microbes active in these reservoirs therefore for the first time in australia a preliminary culture independent survey of the prokaryotic microbial composition of some of these reservoirs was undertaken to provide a basis for an understanding of the origin of the observed biogenic gas four water and three coal samples from the east coast of australia were examined for their prokaryotic diversity by 16s rdna analysis dna was extracted from the samples and amplified using bacterial and archaeal selective primers and the resulting amplicons were cloned and sequenced dna amplicons derived from gram negative bacteria predominated relatively few archaeal and gram positive bacterial sequences were amplified from the original samples by and large coal samples yielded almost exclusively archaeal and proteobacterial amplicons whereas the water samples contained amplicons derived from the remaining proteobacteria e and bacteroidetes amplicons from three genera of archaea were observed none of which were genuine methanogens although the dominant genus archaeoglobus is reported to have some weak methanogenic activity further integrated studies of microbiology hydrochemistry gas geochemistry and geology of cbm reservoirs are continuing in order to better understand the parameters for methane production in eastern australian basins

microbial controls on the origin and evolution of coal seam gases and production waters of the walloon subgroup surat basin australia abstract the walloon subgroup coal seam gas csg play in the surat basin queensland is australia s pre eminent onshore gas field concerted multi disciplinary research is underway investigating the distribution origin and composition of waters and gases in this dominantly microbial csg reservoir to guide both continued production and potential microbially enhanced coal bed methane mecom applications however prior to the present research a detailed study of co produced waters and gases from across the surat basin was not available in the public domain this study tested whether co produced water compositional and stable isotopic data show relationships with production gas stable isotope compositions to elucidate further evidence for microbial co2 reduction and explore the down dip geochemical evolution of walloon coal bed waters and gases a total of 41 wells were sampled with 50 water and 25 gas samples spanning the 3 major production areas of the surat basin detailed isotopic and hydrochemical analysis of these samples revealed distinct spatial trends between the different production locales water compositions were distinct for each of the production regions reflecting the different lithologies of adjacent recharge zones differing fluid rock interactions likely different microbial consortia and the extent of methanogenesis on the western side of the basin near roma waters were the freshest with the lowest median values for alkalinity 861 mg l and cl 588 mg l and a 13cdic of 14 2 on the eastern side of the basin the kogan nose waters were the most saline with the highest median values for na 1955 mg l cl 2280 mg l and 13cdic 20 0 also in the east in the present gas fairway the undulla nose waters had the highest median alkalinity 1841 mg l and were found to have a na excess median 1050 mg l and a lower than expected median 13cdic 14 0 co mingled produced methane carbon isotope values 13c 57 0 to 44 5 from both the upper juandah and lower taroom coal measures plot within the mixed thermogenic microbial genetic field by contrast deuterium isotopic difference 2h h2o ch4 values and cross plots of 2h h2o and 18o h2o suggest that microbially mediated co2 reduction is the dominant methane generation process in situ at a given depth the undulla nose waters in the east are more depleted in 2h and 18o than elsewhere in the surat basin which may suggest these samples have been more heavily impacted by water rock microbial reactions 14c values from the 3 production regions 0 115 to 1 769 pmc age 32 400 to 50 000 years before present b p suggest that walloon coals likely recharged in the last 50 000 years limit of radiocarbon dating consistent with these dates 2h h2o and 18o h2o values for the surat basin 2h 32 to 56 18o 5 9 to 9 0 echo the stable isotopic composition of meteoric waters during the initial part of the last glacial period in southeast queensland based on a strong correlation between 2h ch4 and 2h h2o we suggest that methane was generated since the late pleistocene pca analysis showed a degree of positive correlation between total alkalinity and both the 13cdic median 14 2 and 13c ch4 median 52 1 vectors that is consistent with finite reservoir effects the results inform ongoing studies of gas distribution and origins and mecom potential in the surat basin and underpin a broader study examining aquifer interactions

a relationship between the carbon and hydrogen content of coals and their vitrinite reflectance abstract an empirical relationship between carbon and hydrogen contents of coals and their measured vitrinite reflectances r v max henceforth r o determined from published data for 210 samples of australian coals from more than 60 different seams shows that r o depends upon both the carbon and hydrogen content via the equation r o 5 035 0 0804 c 0 184 h this equation allows prediction of the change in r o when the carbon and or hydrogen content vary the equi reflectance lines plotted on a seyler chart using this equation allow prediction of the variable suppression of r o caused by changes in hydrogen content

the interaction of a pacific cold front with shallow air masses east of the rocky mountains abstract the study presented here describes the interactions that occurred between an advancing pacific cold front and shallow gulf of mexico and arctic air masses situated east of the rocky mountains during the verification of the origins of rotation in tornadoes experiment vortex field campaign on 17 18 april over oklahoma and adjacent states these interactions were driven largely by the complex topography of the region four air masses of distinctly different origin i e pacific polar high altitude continental gulf of mexico and arctic and the boundaries that separated them i e pacific cold front dryline and arctic front were observed within the experimental domain this event produced more than 1 million worth of damage in the experimental domain due to severe weather a dense network of ground based in situ and remote observing systems and two research aircraft equipped with in situ sensors and doppler radars gathered data that allowed the authors to document the passage of a vigoro

patterns of precipitation and mesolow evolution in midlatitude mesoscale convective vortices abstract surface pressure manifestations of mesoscale convective vortices mcvs that traversed oklahoma during the periods may august 2002 05 are studied using the weather surveillance radar 1988 doppler wsr 88d the oklahoma mesonet and the noaa profiler network data forty five mcvs that developed from mesoscale convective systems mcss have been investigated 28 62 of which exhibit mesolows detectable at the surface within this group three distinct patterns of precipitation organization and associated mesolow evolution have been identified the remaining 17 38 of the cases do not contain a surface mesolow two repeating patterns of precipitation organization are identified for the latter group the three categories of mcvs possessing a surface mesolow are as follows nineteen are classified as rear inflow jet mcvs and tend to form within large and intense asymmetric mcss rear inflow into the mcs enhanced by the development of an mcv on the left hand side relative to system motion pro

adjoint tomography of the southern california crust using an inversion strategy based on adjoint methods we developed a three dimensional seismological model of the southern california crust the resulting model involved 16 tomographic iterations which required 6800 wavefield simulations and a total of 0 8 million central processing unit hours the new crustal model reveals strong heterogeneity including local changes of 30 with respect to the initial three dimensional model provided by the southern california earthquake center the model illuminates shallow features such as sedimentary basins and compositional contrasts across faults it also reveals crustal features at depth that aid in the tectonic reconstruction of southern california such as subduction captured oceanic crustal fragments the new model enables more realistic and accurate assessments of seismic hazard

impact of high resolution fwi in the western black sea revealing overburden and reservoir complexity the western black sea wbs is now an area of active petroleum exploration and several seismic surveys have been acquired to support the ongoing activity seismic imaging in the wbs is challenging due to the presence of complex overburden such as canyons shallow gas channels and complex shallow stratigraphy such overburden complexities create amplitude dimming and wipeouts in the images and cause structural distortions of the reservoir units conventional velocity model building and seismic migration methods are not optimal for addressing such challenges full wavefield inversion fwi technology was applied to overcome the complex seismic imaging challenges in the wbs and to support the exploration and development program to date a suite of fwi products has been used to identify shallow hazards derisk prospects optimize well placement perform accurate resource estimation and support development planning unlike traditional seismic migration generated fwi products are not simply depictions of

on the role of density and attenuation in three dimensional multiparameter viscoacoustic vti frequency domain fwi an obc case study from the north sea 3 d frequency domain full waveform inversion fwi is applied on north sea wide azimuth ocean bottom cable data at low frequencies 10 hz to jointly update vertical wave speed density and quality factor q in the viscoacoustic vti approximation we assess whether density and q should be viewed as proxy to absorb artefacts resulting from approximate wave physics or are valuable for interpretation in the presence of soft sediments and gas cloud fwi is performed in the frequency domain to account for attenuation easily multiparameter frequency domain fwi is efficiently performed with a few discrete frequencies following a multiscale frequency continuation however grouping a few frequencies during each multiscale step is necessary to mitigate acquisition footprint and match dispersive shallow guided waves q and density absorb a significant part of the acquisition footprint hence cleaning the velocity model from this pollution low q perturbations correlate with low velocity zones associated with soft sediments and gas cloud however the amplitudes of the q perturbations show significant variations when the inversion tuning is modified this dispersion in the q reconstructions is however not passed on the velocity parameter suggesting that cross talks between first order kinematic and second order dynamic parameters are limited the density model shows a good match with a well log at shallow depths moreover the impedance built a posteriori from the fwi velocity and density models shows a well focused image with however local differences with the velocity model near the sea bed where density might have absorbed elastic effects the fwi models are finally assessed against time domain synthetic seismogram modelling performed with the same frequency domain modelling engine used for fwi

interactions between a developing mesoscale convective system and its environment part i observational analysis this paper is the first in a two part series in which the interactions between a growing mesoscale convective system mcs and its surrounding environment are investigated the system studied here developed in northeastern colorado on 19 july 1993 and propagated into kansas as a long lived nocturnal mcs high resolution dual doppler and surface mesonet data collected from this system are discussed in part i while the results of a numerical simulation are discussed in part ii the observations show that organized mesoscale surface pressure and flow features appeared very early in the lifetime of this system long before the development of any trailing stratiform precipitation most of the stratiform anvil advected ahead of the convective line in the strong upper tropospheric westerlies in accordance with this most of the mid and upper tropospheric storm relative flow behind the line remained westerly or rear to front despite the westerlies the strongest flow perturbations with respect to the ambient winds developed to the rear of the line the structure of these perturbations was similar to the upper tropospheric front to rear and midtropospheric rear to front flows typically found in more mature leading line trailing stratiform systems the presence of these perturbations on the upwind side of the convective line indicates that gravity wave propagation was primarily responsible for their development

mesoscale vertical motions near nocturnal convection initiation in pecan abstractradiosonde measurements from the plains elevated convection at night pecan 2015 field campaign are used to diagnose mesoscale vertical motions near nocturnal convection initiation ci these ci events occur in distinctly different environments including ones with 1 strong forcing for ascent associated with a synoptic cold front and midtropospheric short wave 2 nocturnal low level jets interacting with weaker quasi stationary fronts or 3 the absence of a surface front or boundary altogether radiosonde derived vertical motion profiles in each of these ci environments are characterized by low to midtropospheric ascent the representativeness of these vertical motion profiles is supported by distributions of corresponding mesoscale averages from model produced 0 6 h ensemble forecasts thermodynamic data from radiosondes are then analyzed along with selected model ensemble members to elucidate the role of the vertical motions on subsequent ci in a case with strong forcing for mesoscale asce

observations of elevated convection initiation leading to a surface based squall line during 13 june ihop_2002 abstract the evolution of a mesoscale convective system mcs observed during the international h2o project that took place on the great plains of the united states is described the mcs formed at night in a frontal zone with four initiation episodes occurring between approximately 0000 and 0400 local time radar radiosonde and surface data together show that at least three of the initiation episodes were elevated occurring from moist conditionally unstable layers located above the boundary layer which had been stabilized by previous mcss initiation occurred in northwest southeast oriented lines where a southerly nocturnal low level jet terminated generating elevated convergence one initiation episode was observed using the s band dual polarization doppler radar s pol and occurred at the intersection of this convergence zone with a propagating wave calculations of the scorer parameter were consistent with wave trapping downdrafts from the developing convection generated both waves and bores w

the stratigraphic distribution of inertinite abstract the paper presents the results of an investigation into the stratigraphic distribution of inertinite in humic coals ranging from the silurian to the neogene periods this range equals the time span during which both land plants and atmospheric oxygen evolved the survey is based on a literature study of inertinite in coals covering a variety of depositional environments and climates in all continents the inertinite percentages listed in this paper have been arranged in stratigraphic order they are the mean values based on mineral free whole coal compilations maceral compositions listed in the literature for individual subsections have been averaged to represent complete coal seams beds although this might not have been always possible due to some ambiguity in the published record moreover not all of the published and unpublished information could be used because of poor sample description obscure geographic origin or insufficient stratigraphic information the results show that there have been times in the geological past e g during the late permian in which coals were particularly rich in inertinite compared with other times e g during much of the late tertiary in which many coals contained very little inertinite occasionally such primary global trends were modulated by a diffuse distribution of inertinite percentages that correspond to differences in climate depositional settings e g active orogenic margins versus tectonically inactive shelf margins and other local or regional variations although various mechanisms for the generation of inertinite have been proposed in the past the overall pattern in its stratigraphic distribution supports the notion of incomplete combustion as the main source of inertinite in coal this points to secular variations in the atmospheric oxygen content as an explanation for the global changes in the inertinite distribution while differential subsidence and climatically influenced reaction rates governed regional and local variations in inertinite percentages

upscale evolution of mcss doppler radar analysis and analytical investigation abstract the development of two small mesoscale convective systems mcss in northeastern colorado is investigated via dual doppler radar analysis the first system developed from several initially isolated cumulonimbi which gradually coalesced into a minimal mcs with relatively little stratiform precipitation the second system developed more rapidly along an axis of convection and generated a more extensive and persistent stratiform echo and mcs cloud shield in both systems the volumetric precipitation rate exhibited an early meso scale convective cycle a maximum and subsequent minimum followed by reintensification into a modest mature stage this sequence is similar to that noted previously in the developing stage of larger mcss by mcanelly and cotton they speculated that the early meso convective cycle is a characteristic feature of development in many mcss that is dynamically linked to a rather abrupt transition toward mature stage structure this study presents kinematic evidence in suppo

petrologic and stable isotopic study of the walloon coal measures surat basin queensland peat accumulation under changing climate and base level abstract the late jurassic walloon subgroup recently dated as oxfordian is a productive subbituminous coal seam gas source in the surat basin and can be subdivided from bottom to top into the taroom coal measures the tangalooma sandstone the lower and upper juandah coal measures which have different coal character the lower taroom coals are commonly thick associated with sandstones and interpreted to form as base level is rising creating sodden anoxic conditions for peat accumulation the middle tangalooma to lower juandah contains fewer and thinner coals and transitions upwards from a sandstone to siltstone dominated sequence responding to inundation with the development of floodplain lakes the strata then coarsen upward in both grain size and coal thickness in the upper juandah coal measures which may be eroded by an overlying unit the springbok sandstone this unconformable surface is basin wide and depending on age can be tied into global changes in climate and base level existing models for peat growth under changing base level and the variability in terms of the conditions of peat formation through time as well as throughout the basin are tested environment of peat deposition and changes therein are investigated by petrographic analysis of the walloon coals coupled with high resolution lithotype logging of core and organic stable carbon isotope analysis fine microlayering and abundance of root suberinite telo and detrovitrinite indicate precursory peat formation in a mostly herbaceous marsh to fen environment in which bigger trees are either infrequent or absent except for the lower seams of the taroom coal measures and the upper seams of the lower juandah coal measures where bright bands are thicker 10 mm and more frequent no extended periods of dehydration oxidation stable carbon isotopes of coal show a distinct positive shift in the lower juandah coal measures that sets in well before the increased inertinite content in the upper juandah coal measures the enrichment in 13 c could be linked to a change in climate during the high stand depositional cycle marking the onset of late stage falling where base level begins to drop later creating exposures and water stress a shift to a less humid climate in the upper juandah coal measures could have favoured the conditions for desiccation mouldering and bush fires which is reflected in the coal s maceral composition the surat basin 13 c isotope trend follows the global trend found in marine carbonate samples from the same age interval that corroborates increasing enrichment towards the top of the coal measures approximately middle oxfordian followed by a shift to more negative compositions which corresponds to the onset of the springbok sandstone deposition on an unconformable surface

a case study of the interaction of a mesoscale gravity wave with a mesoscale convective system abstractthis study documents the high amplitude mesoscale gravity wave mgw event of 7 march 2008 in which two mgws strongly impacted the sensible weather over a large portion of the southeast united states these mgws exhibited starkly contrasting character despite propagating within similar environments the primary i e long lived mgw was manifest by a solitary wave of depression associated with rapid sinking motion and adiabatic warming while the secondary short lived mgw was manifest by a solitary wave of elevation mgwel dominated by rising motion and moist adiabatic cooling genesis of the primary mgw occurred as a strong cold front arrived at the foot of mexico s high terrain and perturbed the appreciable overriding flow the resulting gravity wave became ducted in the presence of a low level frontal stable layer and caused surface pressure falls up to 4 hpa the mgw later amplified as it became coupled with a stratiform precipitation system which led to its evolution into an intense

estimating p and s wave inverse quality factors from observed seismic data using an attenuative elastic impedance p and s wave inverse quality factors quantify seismic wave attenuation which are related to several key reservoir parameters porosity saturation viscosity etc estimating the inverse quality factors from observed seismic data provides additional and useful information during gas bearing reservoir prediction we first propose an approximate reflection coefficient and attenuative elastic impedance in terms of the inverse quality factors and then we establish an approach to estimate elastic properties p and s wave impedances and density and attenuation p and s wave inverse quality factors from seismic data at different incidence angles and frequencies the approach is implemented as a two step inversion a model based and damped least squares inversion for attenuative elastic impedance and a bayesian markov chain monte carlo inversion for the inverse quality factors synthetic data tests confirm that p and s wave impedances and inverse quality factors are reasonably estimated in the case of

inversion of the seismic avf ava signatures of highly attenuative targets frequency dependent seismic field data anomalies appearing in association with low q targets have on occasion been attributed to the presence of a strong absorptive reflection coefficient this absorptive reflectivity represents a potent and largely untapped source of information for determining subsurface target properties it would most likely be encountered where a predominantly elastic nonattenuating overburden suddenly is interrupted by a highly attenuative target series expansions of absorptive reflection coefficients about small parameter contrasts and incidence angles can expose these anomalies to analysis either frequency by frequency amplitude variation with frequency avf or angle by angle amplitude variation with angle of incidence ava within this framework variations in p wave velocity and q can be estimated separately through a range of direct formulas both linear and with nonlinear corrections the latter come to the fore when a contrast from an incidence medium q i

improved seismic image by q compensated reverse time migration application to crosswell field data west texas abstractto test the effectiveness of the q compensated reverse time migration q rtm method we applied it to crosswell seismic data from western texas this crosswell field survey was aimed at determining the boundaries and even the internal features of the reservoir in this area the reservoir geologic body exhibits strong attenuation that reduces high frequencies more rapidly thus conventional acoustic rtm produces a dimmed image reduced amplitude and low resolution of the reservoir area and structures underneath in contrast q rtm is able to compensate for the attenuation effects during imaging the vp and qp profiles needed for q rtm were produced by joint traveltime and frequency shift tomography preprocessing of the data was carried out to reduce noise remove tube waves and to separate up and downgoing wavefields along with recovered high wavenumbers the final q rtm image provided many details about geologic layers and structures the lateral and vertical extent and internal structures

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

the occurrence of a secondary zone of coal bed methane in the southern part of the upper silesian coal basin southern poland potential for methane exploitation abstract coal bed methane cbm exploitation in the upper silesian coal basin has in spite of earlier failures again aroused investor interest carboniferous coal seams at depths of 200 500 m are characterized by coal permeability values estimated at 27 230 md and degrees of methane saturation almost 100 that suggest future successful exploitation based on the results of geological surveys archived in the polish geological institute the shallow cbm zone is defined as a gas horizon distinct from a deep cbm zone the disposition of the shallow zone follows the topography of the upper carboniferous paleorelief and is deemed the most important factor controlling methane distribution within this zone the most favorable places for cbm accumulation within the shallow coal seams are erosional highs and the slopes of upper carboniferous ridges associated with fault zones the thickness of the zone 200 m and methane contents 8 m 3 t coal daf are highest in these places the nearly full saturation of the coal seams with methane reflects the involvement of two genetic types of gas indigenous late stage microbial methane and thermogenic methane derived from the deeper coals the favorable geological characteristic of this shallow cbm zone is a potential source of energy for upper silesia

stable isotopic and molecular composition of desorbed coal seam gases from the walloon subgroup eastern surat basin australia this study used compositional and stable isotopic analysis to test hypotheses on the distribution and origins of walloon subgroup coal seam gas csg in the eastern surat basin queensland australia the middle jurassic walloon subgroup play differs from many other low rank csg plays particularly in methane carbon isotopic signature i e the csg is not as microbial as could be expected the carbon isotope compositions of desorbed methane from three cored appraisal wells fall within the generally accepted range for thermogenic or mixed gas 13c 58 5 to 45 3 the 13c ch4 values from stratigraphically placed coal core samples increased became more thermogenic from the top of the upper juandah coal measures to the base of the tangalooma sandstone below the tangalooma sandstone in the lower taroom coal measures the 13c ch4 values decreased with increasing depth these positively parabolic 13c profiles tracked total measured gas content in two out of the three wells studied the third well displayed lower variance of 13c ch4 and gas content increased uniformly with depth a genetic classification based on methane stable carbon isotopes alone might interpret this pattern as a transition from microbially to thermogenically sourced methane in the central coal seams however a 13c co2 profile for one well tracks total gas content and 13c ch4 and exhibits an inverse relationship with d ch4 these results together with the mostly dry nature of the gas samples c1 c2 c3 ratios up to 10 000 and relatively uniform d ch4 values d 238 to 202 suggest that microbial co2 reduction is the primary source of walloon subgroup methane as such stratigraphic variations in gas content mainly reflect the extent of microbial methanogenesis we suggest that peak microbial utilisation of h2 co2 occurred at the tangalooma sandstone level enriching the residual co2 pool and derived methane in 13c carbon 13c co2 ch4 and deuterium isotopic differences d h2o ch4 and cross plots of d h2o and 18o h2o are also consistent with kinetic isotope fractionation during microbial mediated carbonate reduction the results are relevant for applying microbially enhanced coal bed methane mecom in the surat basin

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

q model building using one way wave equation migration q analysis part 2 3d field data test in part one of this paper we presented an inversion based method wave equation migration q analysis to estimate the quality factor q model for seismic attenuation to demonstrate the feasibility of this method we applied this method to a 3d seismic dataset acquired in the north sea attenuation problems caused by a shallow gas and a shallow channel are observed in this field this study aims at characterizing these attenuation anomalies these attenuation anomalies are correlated with low interval velocities the provided velocity model does not accurately reflect the low velocity anomalies therefore we first applied wave equation migration velocity analysis to update the provided velocity model the updated velocity shows low velocity regions around the gas and channel features the subsurface angle gathers migrated using the updated velocity model are flatter and the events in the migrated images after velocity updating are more coherent then we applied wave equation migration q analysis to inv

analytical variation in australian coals related to coal type and rank analyses of australian coals ranging in age from permian to miocene are reviewed principally by using the van krevelen diagram atomic o c vs h c but also by plotting calorific value vs volatile matter groups of coals of particular ages or from particular areas or seams within coalfields plot in well defined parts of the diagrams each group however covers only part of the rank range from lignite to semi anthracite accordingly the new zealand nz coal band based on medium to high h c late cretaceous and cenozoic coals is used as a reference maturation path the extremes of h c in low rank australian coals are shown by the particularly high h c jurassic queensland coals and the low h c triassic queensland callide coals the majority of coals plot between these extremes these include cenozoic victorian lignites brown coals which except for high h c pale and light lithotypes are similar to new zealand lignites vitrains from australian permian coals plot across the width of the nz coal band and the range of permian coals extends into much lower h c parts of the van krevelen diagram the spectrum of all coals is continuous throughout the extensive range of h c comparison with data on maceral group compositions shows close relations between h c ratios and the proportion of vitrinite provided allowance is made for the counteracting effects of high h c liptinite and low h c inertinite in most coals vitrinite is the dominant maceral group and the range of h c ratios of vitrain samples from permian coals shows that vitrinite composition also must be significant in influencing the elemental composition of the heterogenous coal

the linear dynamics of squall line mesohighs and wake lows two surface pressure features that commonly accompany squall lines the mesohigh and the wake low may be explained at least in part as a linear response to the low level cooling associated with stratiform precipitation this response is numerically simulated for two and three dimensional moving and stationary low level coolings characteristic of squall line stratiform regions when the cooling is defined to move and to have three dimensional structure both a mesohigh and a mesolow develop and their structures and evolutions resemble those of squall line mesohighs and wake lows when an upper boundary is introduced directly above the cooling the response approaches a steady state in which a mesohigh mesolow couplet is centered on the cooling the simulations and the steady state analysis presented here help to explain observed characteristics of squall line mesohighs and wake lows including their life cycles and positioning relative to precipitation structures

conceptual exploration targeting for microbially enhanced coal bed methane mecom in the walloon subgroup eastern surat basin australia abstract the sustainable in situ regeneration of microbial biogenic methane or microbially enhanced coal bed methane mecom is an emerging concept being investigated globally promising results and recommendations of a preliminary culture study of walloon subgroup co produced coal seam gas csg waters from the surat basin queensland established the presence of viable methanogens and suggested that in situ methanogenesis could be stimulated using physical and chemical reservoir treatments this paper represents the culmination of a stepwise basin analysis project ultimately aimed at siting potential in situ bioreactor locations in the eastern surat basin the integration of stratigraphically located data on the molecular and isotopic composition of desorbed gases host coal properties and spatially associated waters through the core production zone has allowed the spatial variability and relative influence of hydro geological factors on methanogenesis to be evaluated in detail for the first time higher gas contents and systematically enriched ch 4 and co 2 carbon isotopic compositions in the stratigraphically central coal seams oldest youngest in the upper taroom coal measures tangalooma sandstone lower juandah coal measures are best explained by increased rates of microbial co 2 reduction and substrate depletion there is a building case to trial mecom in the central coal seams in a depleted underperforming well in an area of high permeability integrated microbiological chemical engineering hydro chemical and geological studies are ongoing to further enhance understanding of walloon subgroup csg and the bioreactor potential of the surat basin

seismic attenuation tomography using the frequency shift method we present a method for estimating seismic attenuation based on frequency shift data in most natural materials seismic attenuation increases with frequency the high frequency components of the seismic signal are attenuated more rapidly than the low frequency components as waves propagate as a result the centroid of the signal s spectrum experiences a downshift during propagation under the assumption of a frequency independent q model this downshift is proportional to a path integral through the attenuation distribution and can be used as observed data to reconstruct the attenuation distribution tomographically the frequency shift method is applicable in any seismic survey geometry where the signal bandwidth is broad enough and the attenuation is high enough to cause noticeable losses of high frequencies during propagation in comparison to some other methods of estimating attenuation our frequency shift method is relatively insensitive to geometric spreading reflection and transmission effects source and receiver coupling and radiation patterns and instrument responses tests of crosswell attenuation tomography on 1 d and 2 d geological structures are presented

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

anisotropic 3d full waveform inversion abstractwe have developed and implemented a robust and practical scheme for anisotropic 3d acoustic full waveform inversion fwi we demonstrate this scheme on a field data set applying it to a 4c ocean bottom survey over the tommeliten alpha field in the north sea this shallow water data set provides good azimuthal coverage to offsets of 7 km with reduced coverage to a maximum offset of about 11 km the reservoir lies at the crest of a high velocity antiformal chalk section overlain by about 3000 m of clastics within which a low velocity gas cloud produces a seismic obscured area we inverted only the hydrophone data and we retained free surface multiples and ghosts within the field data we invert in six narrow frequency bands in the range 3 to 6 5 hz at each iteration we selected only a subset of sources using a different subset at each iteration this strategy is more efficient than inverting all the data every iteration our starting velocity model was obtained using standard psdm model bui

relationships between major ions in coal seam gas groundwaters examples from the surat and clarence moreton basins abstract using a combination of multivariate statistical techniques and the graphical assessment of major ion ratios the influences on hydrochemical variability of coal seam gas or coal bed methane groundwaters from several sites in the surat and clarence moreton basins in queensland australia were investigated several characteristic relationships between major ions were observed 1 strong positive linear correlation between the na cl and alkalinity cl ratios 2 an exponentially decaying trend between the na cl and na alkalinity ratios 3 inverse linear relationships between increasing chloride concentrations and decreasing ph for high salinity groundwaters and 4 high residual alkalinity for lower salinity waters and an inverse relationship between decreasing residual alkalinity and increasing chloride concentrations for more saline waters the interpretation of the hydrochemical data provides invaluable insights into the hydrochemical evolution of coal seam gas csg groundwaters that considers both the source of major ions in coals and the influence of microbial activity elevated chloride and sodium concentrations in more saline groundwaters appear to be influenced by organic bound chlorine held in the coal matrix a sodium and chloride ion source that has largely been neglected in previous csg groundwater studies however contrastingly high concentrations of bicarbonate in low salinity waters could not be explained and are possibly associated with a number of different factors such as coal degradation methanogenic processes the evolution of high bicarbonate nahco 3 water types earlier on in the evolutionary pathway and variability in gas reservoir characteristics using recently published data for csg groundwaters in different basins the characteristic major ion relationships identified for new data presented in this study were also observed in other csg groundwaters from australia as well as for those in the illinois basin in the usa this observation suggests that where coal maceral content and the dominant methanogenic pathway are similar and where organic bound chlorine is relatively abundant distinct hydrochemical responses may be observed comparisons with published data of other nahco 3 water types in non csg environments suggest that these characteristic major ion relationships described here can i serve as an indicator of potential csg groundwaters in certain coal bearing aquifers that contain methane and ii help in the development of strategic sampling programmes for csg exploration and to monitor potential impacts of csg activities on groundwater resources

a study of different methods of wavefield separation for application to vsp data1 during the last couple of years there has been much research in the area of wavefield separation of borehole seismic data and several articles have been published on various separation techniques methods involving the application of two dimensional fourier transformation the radon transformation multi level median filters or optimal filters are all suggested as possible approaches to the wavefield separation problem this paper compares some of these methods commonly used in the industry the theories of the chosen methods are described to see how they are related using the different methods on synthetic and real data we show how this theoretical relation is reflected in the relatively similar results obtained we also show how the different filters treat coherent and random noise

variation in pyrolysate composition of sediments from the jurassic walloon coal measures eastern australia as a function of thermal maturation examination of a natural maturity sequence from the jurassic walloon coal measures by quantitative flash pyrolysis gas chromatography py gc and low temperature sealed tube pyrolysis reveals systematic changes in pyrolysate composition in particular gas to oil ratios composition of gas and liquid normal hydrocarbons aromatic and heteroatom content are examined for this immature oil prone rock as it is taken artificially and naturally through the oil window liquid hydrocarbon generation giving a product with a high wax content is shown to occur over a relatively narrow range of maturation significant quantities of gas are generated and the gas to oil ratio remains relatively constant during the main phase of oil generation this reflects a uniform distribution of oil and gas precursors in the original labile kerogen at higher rank where increasing generation from the residual refractory kerogen occurs there is a progressive decrease in the yield of liquid hydrocarbons concomitant with an increase in the gas to oil ratio

the influence of macroscopic texture on biogenically derived coalbed methane huntly coalfield new zealand abstract secondary biogenic gas content can be related to textural characteristics in eocene age subbituminous coals from the huntly coalfield new zealand however the relationships between the two major coal seams in the basin are considerably different despite their close stratigraphic proximity less than 25 m in this study 163 coal samples were collected and desorbed from eight drill holes gas adsorption capacity and proximate analyses were conducted as well as macroscopic logging for coal type and vitrain banding characteristics vitrain bands were quantitatively point counted and the longest dimension of the shortest axis measured three coal types were recognized bright luster non banded bright moderately banded and bright highly banded vitrain band thickness converted to the phi log 2 scale was found to increase across the coal types with the thickest bands being associated with the most banded coal type overall when normalized by seam and location the dataset reveals a relationship between coal type and gas content with the non banded coal type having the highest gas contents and conversely the coal types with the most vitrain bands having the lowest gas contents however when the seams are considered separately it can be seen that in the stratigraphically higher renown coal seam gas has an indirect association with increasing band thickness in agreement with the overall trend while the stratigraphically lower kupakupa coal seam appears to have a direct relationship interestingly the renown seam which has a greater percentage of non banded material generally has a greater methane adsorption capacity as well as a greater gas content compared to the kupakupa seam it is believed these differences are related to macroscopic texture and that the differing proportions of the coal types between the two seams has a fundamental effect on microporosity ultimately controlling the available surface area for gas adsorption

determination of rank and petrographic composition of jurassic coals from eastern surat basin australia abstract petrographic analysis and rank determination were carried out on coals from a jurassic sequence in eastern surat basin australia the coals consist mainly of exinite rich clarite with desmocollinite as dominant maceral of the vitrinite group petrographically there is no significant variation in the composition of the coals a herbaceous swamp type free from severe oxidation dehydration appears to have been a dominant depositional environment during the peat accumulation the coal rank ranges from sub bituminous b to high volatile bituminous c b vitrinite reflectance depth profile shows a uniform increase in coalification with depth of burial

variable gas saturation in coalbed methane reservoirs of the black warrior basin implications for exploration and production abstract gas saturation is highly variable in carboniferous coalbed methane reservoirs of the black warrior basin usa and diverse geologic data derived from more than three decades of exploration and development provides insight into the origin of this variability and the consequences for production performance coalbed methane is produced from numerous thin 0 3 to 95 importantly this range of variation is commonly developed among closely spaced seams within the same well exploration has to date been successful where coal seams are in the thermogenic gas window geochemical evidence indicates that thermogenic gases have been altered by subsurface water movement and may have been augmented with late stage biogenic gases particularly in areas affected by fresh water recharge adsorption isotherms of coal samples in the black warrior basin typically have langmuir volume between 15 and 30 cm3 g and langmuir pressure between 2 and 6 mpa both langmuir pressure and langmuir volume correlate significantly with coal rank in deep normally pressured coal beds where reservoir pressure is substantially above langmuir pressure even a small degree of undersaturation can necessitate prolonged dewatering before a large reservoir volume can reach the critical desorption pressure permeability moreover decreases exponentially with depth which can make dewatering coal seams deeper than 800 m difficult where reservoir pressure is relatively low however isotherm geometry indicates that significantly undersaturated reservoirs can be near the critical desorption pressure consequently areas of underpressure favor high gas production along with minimal water production

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

development of the first coal seam gas exploration program in indonesia reservoir properties of the muaraenim formation south sumatra abstract the late miocene muaraenim formation in southern sumatra contains thick coal sequences mostly of low rank ranging from lignite to sub bituminous and it is believed that these thick low rank coals are the most prospective for the production of coal seam gas csg otherwise known as coalbed methane cbm in indonesia as part of a major csg exploration project gas exploration drilling operations are being undertaken in rambutan gasfields in the muaraenim formation to characterize the csg potential of the coals the first stage of the project which is described here was designed to examine the gas reservoir properties with a focus on coal gas storage capacity and compositional properties some five csg exploration boreholes were drilled in the rambutan gasfield south of palembang the exploration boreholes were drilled to depths of 1000 m into the muaraenim formation five major coal seams were intersected by these holes between the depths of 450 and 1000 m the petrography of coal samples collected from these seams showed that they are vitrinite rich with vitrinite contents of more than 75 on a mineral and moisture free basis gas contents of up to 5 8 m 3 t were measured for the coal samples the gas desorbed from coal samples contain mainly methane ch 4 ranging from 80 to 93 and carbon dioxide co 2 ranging from 6 to 19 the composition of the gas released into the production borehole well is however much richer in ch 4 with about 94 to 98 ch 4 and less than 5 co 2 the initial results of drilling and reservoir characterization studies indicate suitable gas recovery parameters for three of the five coal seams with a total thickness of more than 30 m

origin evolution and finescale structure of the st valentine s day mesoscale gravity wave observed during storm fest part iii gravity wave genesis and the role of evaporation abstract on 14 february 1992 a long lived moderate amplitude mesoscale gravity wave formed in kansas during the storm scale operational and research meteorology fronts experiment systems test storm fest wave formation was evident in correlated surface pressure and wind fields the wave of depression accompanied by a weak rainband tracked across the state a wealth of data was collected on the mature wave as it passed over the storm fest dual doppler domain however the mechanism of genesis remained difficult to ascertain since wave formation occurred in a region of less comprehensive observations the genesis of the storm fest gravity wave is successfully simulated using the fifth generation pennsylvania state university national center for atmospheric research penn state ncar mesoscale model mm5 which was run at 6 km grid spacing in the innermost domain the lee cyclone movement dry airmass development and gravity wave formation over kansas were successfully captured by the model results

mesoscale surface pressure and temperature features associated with bow echoes abstract this study examines observed mesoscale surface pressure temperature and wind features of bow echoes bow echo events in the area of the oklahoma mesonet are selected for study to take advantage of high resolution surface data thirty six cases are identified using 2 km resolution radar reflectivity data over a 4 yr period 2002 05 their surface features are interrogated using the mesonet data distinct surface features usually associated with squall lines the mesohigh and cold pool are found to also accompany bow echoes a common surface pattern preceding bowing is identified prior to new bowing development the mesohigh surges ahead of the convective line while the cold pool remains centered behind it surface winds shift to a ground relative outflow pattern upon arrival of the mesohigh surge approximately 30 min later a new bowing segment forms with its apex slightly to the left with respect to the direction of system motion of the mesohigh surge the cold pool follows the convective

the wake low in a midlatitude mesoscale convective system having complex convective organization abstract an analysis has been carried out of the surface pressure field in a highly complex mesoscale convective system that occurred on 3 4 june 1985 during the oklahoma kansas preliminary regional expeximent for storm central ok pre storm during its mature stage the storm consisted of two primary intersecting convective bands approximately 200 km in length one oriented nie sw to the north and the other n s to the south with a stratiform precipitation region extending to the northwest of the bands stratifonn precipitation was weak to nonexistent in the southernmost portion of the storm although the organization of the storm was complex the surface pressure field resembled those associated with simpler quasi linear squall systems containing trading stratifom regions a mesohigh existed neat the convective line and a wake low was observed to the rear of the stratiform region a strong system relative descending rear inflow jet was observed in the northern part of the storm near the wake low

thermodynamic properties of mesoscale convective systems observed during bamex dropsonde observations from the bow echo and mesoscale convective vortex experiment bamex are used to document the spatiotemporal variability of temperature moisture and wind within mesoscale convective systems mcss onion type sounding structures are found throughout the stratiform region of mcss but the temperature and moisture variability is large composite soundings were constructed and statistics of thermodynamic variability were generated within each subregion of the mcs the calculated air vertical velocity helped identify subsaturated downdrafts it was found that lapse rates within the cold pool varied markedly throughout the mcs layered wet bulb potential temperature profiles seem to indicate that air within the lowest several kilometers comes from a variety of source regions it was also found that lapse rate transitions across the 0 c level were more common than isothermal melting layers the authors discuss the implications these findings have and how they can be used to validate future high resolution numerical simulations of mcss

the determination of the seismic quality factor q from vsp data a comparison of different computational methods1 ten methods for the computation of attenuation have been investigated namely amplitude decay analytical signal wavelet modelling phase modelling frequency modelling rise time pulse amplitude matching technique spectral modelling and spectral ratio in particular we have studied the reliability of each of these methods in estimating correct values of q using three synthetic vsp seismograms for plane p waves with different noise contents the investigations proved that no single method is generally superior rather some methods are more suitable than others in specific situations depending on recording noise or geology the analytical signal method has been demonstrated to be superior if true amplitude recordings are available otherwise spectral modelling or in the noise free case the spectral ratio method is optimal finally two field vsps in sediments are investigated only in the case of the highest quality vsp can significant information be deduced from the computed attenuation