geomorphological significance of at many stations hydraulic geometry the critically important at a station hydraulic geometry ahg relationships relate hydraulic variables depth width or velocity to discharge in power law form the recently discovered at many stations hydraulic geometry amhg states that ahg exponents and coefficients are strongly correlated removing one parameter and lending amhgs to remote sensing discharge estimation despite the excitement there is an urgent need to clarify amhg s geomorphological significance for different hydraulic variables using data from 57 rivers in the u s and perturbation experiments we show that the width amhg is weak arising mainly from the mathematical construct involving the exponent in both the regressor and the regressand in contrast the depth amhgs result from geomorphological coevolution the similar time mean condition as argued for in the literature is sufficient but not necessary for rating curve convergence and in turn amhg for depth and velocity the predictive accuracy of amhgs whose coefficient of determination is unit dependent is similar to the flow percentile based downstream hydraulic geometry

verifying the prevalence properties and congruent hydraulics of at many stations hydraulic geometry amhg for rivers in the continental united states abstract hydraulic geometry hg has long enabled daily discharge estimates flood risk monitoring and water resource and habitat assessments among other applications at many stations hg amhg is a newly discovered form of hg with an evolving understanding amhg holds that there are temporally and spatially invariant congruent depth width velocity and discharge values that are shared by all stations of a river furthermore these river wide congruent hydraulics have been shown to link at a station hg ahg in space contrary to previous expectation of ahg as spatially unpredictable to date amhg has only been thoroughly examined on six rivers and its congruent hydraulics are not well understood to address the limited understanding of amhg we calculated amhg for 191 rivers in the united states using usgs field measured data from over 1900 gauging stations these rivers represent nearly all geologic and climatic settings found in the continental u s and allow for a robust assessment of amhg across scales over 60 of rivers were found to have amhg with strong explanatory power to predict ahg across space defined as r 2 0 6 118 191 rivers we also found that derived congruent hydraulics bear little relation to their observed time varying counterparts and the strength of amhg did not correlate with any available observed or congruent hydraulic parameters we also found that amhg is expressed at all fluvial scales in this study some statistically significant spatial clusters of rivers with strong and weak amhg were identified but further research is needed to identify why these clusters exist thus this first widespread empirical investigation of amhg leads us to conclude that amhg is indeed a widely prevalent natural fluvial phenomenon and we have identified linkages between known fluvial parameters and amhg our work should give confidence to future researchers seeking to perform the necessary detailed hydraulic analysis of amhg

geologic framework of the mississippian barnett shale barnett paleozoic total petroleum system bend arch fort worth basin texas this article describes the primary geologic characteristics and criteria of the barnett shale and barnett paleozoic total petroleum system tps of the fort worth basin used to define two geographic areas of the barnett shale for petroleum resource assessment from these two areas referred to as assessment units the u s geological survey estimated a mean volume of about 26 tcf of undiscovered technically recoverable hydrocarbon gas in the barnett shale the mississippian barnett shale is the primary source rock for oil and gas produced from paleozoic reservoir rocks in the bend arch fort worth basin area and is also one of the most significant gas producing formations in texas subsurface mapping from well logs and commercial databases and petroleum geochemistry demonstrate that the barnett shale is organic rich and thermally mature for hydrocarbon generation over most of the bend arch fort worth basin area in the northeastern and structurally deepest part of the fort worth basin adjacent to the muenster arch the formation is more than 1000 ft 305 m thick and interbedded with thick limestone units westward it thins rapidly over the mississippian chappel shelf to only a few tens of feet the barnett paleozoic tps is identified where thermally mature barnett shale has generated large volumes of hydrocarbons and is 1 contained within the barnett shale unconventional continuous accumulation and 2 expelled and distributed among numerous conventional clastic and carbonate rock reservoirs of paleozoic age vitrinite reflectance ro measurements show little correlation with present day burial depth contours of equal ro values measured from barnett shale and typing of produced hydrocarbons indicate significant uplift and erosion furthermore the thermal history of the formation was enhanced by hydrothermal events along the ouachita thrust front and mineral wells newark east fault system stratigraphy and thermal maturity define two gas producing assessment units for the barnett shale 1 a greater newark east fracture barrier continuous barnett shale gas assessment unit encompassing an area of optimal gas production where dense impermeable limestones enclose thick 300 ft 91 m barnett shale that is within the gas generation window ro 1 1 and 2 an extended continuous barnett shale gas assessment unit covering an area where the barnett shale is within the gas generation window but is less than 300 ft 91 m thick and either one or both of the overlying and underlying limestone barriers are absent

correlation of reservoired gases using the carbon isotopic compositions of wet gas components the carbon isotopic compositions of the wet gas components particularly propane isobutane and normal butane have been found to be particularly valuable for correlating one reservoired gas with another the usefulness of these components for correlation results from their carbon isotopic compositions reflecting both the nature of their source and their maturity this source control is strongest for gases derived from the more highly structured types of kerogen i e woody coaly type iii although the wet gas components carbon isotopic compositions of most gases are at least partly controlled by their source for levels of maturity below the point at which thermal destruction of the wet components occurs as a result the wet gas components are found to provide more ositive correlations than is methane alone three exploration examples illustrate the use of the carbon isotopic compositions of the wet gas components for correlation the leduc reef trend of alberta canada the sleipner area in the north sea and the lena field offshore louisiana united states the three examples also illustrate the need to integrate geochemical interpretations with regional geology to obtain a good understanding of the hydrocarbon source

geochemical characteristics of the extremely high thermal maturity transitional shale gas in the southern north china basin sncb and its differences with marine shale gas abstract a great number of studies have been carried out on the geochemical characteristics of marine shale gas from the lower silurian longmaxi formation in the sichuan basin however a systematic study on geochemical and isotopic characteristics of transitional shale gas gas from the alternating marine terrigenous shale facies has not been well addressed in the present study transitional shale gas from the lower permian shanxi p1s and taiyuan p1t formation in the southern north china basin sncb were collected and analyzed for their geochemical and isotopic compositions the hydrocarbon gases are dominated by methane with small amounts of ethane without propane and butane which is consistent with the extremely high thermal maturity of the gas shales ro values between 3 2 and 4 2 compared with marine shale gas the relatively high non hydrocarbon components may be associated with the humic source rocks the 13c1 values range from 31 6 to 21 0 and the 13c2 values range from 35 9 to 26 1 the 2hch4 values range from 221 to 138 these results indicate that the gases are of thermogenic origin methane with anomalous heavy carbon isotopic and light hydrogen isotopic values was interpreted as redox reactions of gases with transition metals and water at maximum burial resulting in rayleigh type fractionation the difficulties of identifying marine and transitional shale gas may be due to the complete or partial carbon isotopic reversal caused by secondary alteration and the extremely high thermal maturity of the gas shales co2 concentration and 13c co2 values suggest that co2 in the transitional shale gas was mainly thermogenic origin and formed together with hydrocarbon generation furthermore significant differences can be observed from the co2 in different types of shale gas co2 in the transitional shale gas is mainly distributed in areas with co2 5 and 13c co2 8 the 15n n2 values and high illite and illite smectite mixed clay i s content suggest that nitrogen in transitional shale gas was possibly generated during thermo ammoniation of organic matter and or the breakdown of nh4 rich clay minerals in addition based on the geochemical characteristics of marine and transitional shale gas a geochemical pattern of shale gas is presented in this paper

field determination of the three dimensional hydraulic conductivity tensor of anisotropic media 2 methodology and application to fractured rocks the analytical solutions developed in the first paper can be used to interpret the results of cross hole tests conducted in anisotropic porous or fractured media in the particular case where the injection and monitoring intervals are short relative to the distance between them the test results can be analyzed graphically from the transient variation of hydraulic head in a given monitoring interval one can determine the directional hydraulic diffusivity kd e ss and the quantity d ss by curve matching here kd e is directional hydraulic conductivity parallel to the unit vector e pointing from the injection to the monitoring interval ss is specific storage and d is the determinant of the hydraulic conductivity tensor k the principal values and directions of k together with ss can then be evaluated by fitting an ellipsoid to the square roots of the directional diffusivities ideally six directional measurements are required in practice a larger number of measurements is often necessary to enable fitting an ellipsoid to the data by least squares if the computed kd e ss values fluctuate so severely that a meaningful least squares fit is not possible one has a direct indication that the subsurface does not behave as a uniform anisotropic medium on the scale of the test test results from a granitic rock near oracle in southern arizona are presented to illustrate how the method works for fractured rocks at the site the oracle granite is shown to respond as a near uniform anisotropic medium the hydraulic conductivity of which is strongly controlled by the orientations of major fracture sets the cross hole test results are shown to be consistent with the results of more than 100 single hole packer tests conducted at the site

a topological system for delineation and codification of the earth s river basins abstract a comprehensive reference system for the earth s river basins is proposed as a support to river basin management global change research and the pursuit of sustainable development a natural system for delineation and codification of basins is presented which is based upon topographic control and the topology of the river network these characteristics make the system well suited for implementation and use with digital elevation models dems and geographic information systems a demonstration of these traits is made with the 30 arcsecond gtopo30 dem for north america the system has additional appeal owing to its economy of digits and the topological information that they carry this is illustrated through presentation of comparisons with usgs hydrologic unit codes and demonstration of the use of code numbers to reveal dependence or independence of water use activities within a basin

molecular and isotopic compositions and origin of natural gases from cambrian and carboniferous lower permian reservoirs of the onshore polish baltic region natural gases from middle cambrian and carboniferous lower permian reservoirs of the onshore polish baltic region were studied for their molecular and stable isotope compositions the following gas species were analysed 12 13c in ch4 c2h6 c3h8 n c4h10 i c4h10 and co2 1 2h in ch4 14 15n in n2 and stable isotopes of all noble gases due to significantly different geological settings and genetic types of source rocks of eastern and western pomerania the molecular and isotopic compositions of natural gases of these two regions exhibit distinct differences hydrocarbon gases associated with oil accumulated in the middle cambrian reservoir of eastern pomerania were generated during low temperature thermogenic processes from a single source rock containing type ii kerogen at one phase of petroleum generation non associated hydrocarbon gases accumulated in the carboniferous mississippian and pennsylvanian lower permian rotliegend reservoirs of western pomerania originated during at least two phases of gas generation by thermogenic processes from mainly type iii kerogen and a small component of mixed type iii ii kerogen noble gases are in general heavily enriched in radiogenic and nucleogenic isotopes such as 4he 40ar and 21ne accumulated in the reservoirs weak contributions of mantle derived he and ne are observed radiogenic 4he 40ar ratios are higher than the average production rate ratio of about 5 for radiogenic 4he 40ar in crustal materials which might have been caused by a selective supply of 4he that is lighter than 40ar from crustal rocks or u th k ratio might be higher than the average in crustal block carbon dioxide from gases of both the western and eastern pomerania were mainly generated during thermogenic processes of transformation of organic matter although gases of western pomerania can contain an endogenic component molecular nitrogen from the eastern pomeranian natural gases was mainly generated during low temperature thermal transformation of organic matter and derived from nh3 and nh4 of crustal fluid whereas molecular nitrogen from western pomeranian natural gases contains a significant component from the destruction of organic matter at a higher maturity level which may have been caused by a high heat flux from the volcanic activity during late pennsylvanian early rotliegend ages and has a bigger component release from nh4 rich illites

carbon isotope reversal and its relationship with natural gas origins in the jingbian gas field ordos basin china abstract the geochemical characteristics of natural gases from lower paleozoic jingbian gas field are abnormal and the carbon isotope of most natural gases has reversed which led to a dispute over the source of natural gas in the lower paleozoic the upper paleozoic yulin gas field is adjacent to the jingbian gas field but the geochemical characteristics of the yulin gas field did not appear abnormal besides the ethane carbon isotope of upper paleozoic yulin gas field is much higher than that of lower paleozoic jingbian gas field in order to identify the reasons for the carbon isotope reversal of natural gas in lower paleozoic jingbian gas field and its relationship with natural gas source we conducted the components and stable carbon isotopes of natural gas from upper paleozoic yulin gas field and lower paleozoic jingbian gas field on the basis of these experiments we compared the natural gas components and carbon isotope of 100 samples from both upper paleozoic yulin gas field and lower paleozoic jingbian gas field the results indicate that higher maturity will break the conventional rule when maturity reaches a certain threshold 13cethane value will decrease with maturity although 13cmethane value will also increase with maturity the extent will be relatively smaller this leads to unusual 13cmethane 13cethane in the region with higher maturity in the process of downward migration of coal derived gas from carboniferous permian coal measures component fractionation and carbon isotope fractionation might occur resulting the ethane components and carbon isotope value of lower paleozoic less than those of upper paleozoic which will lead to the carbon isotope reversal the mixing of oil derived gas and coal derived gas at different ratios may also lead to the reversal of carbon isotopes the natural gas types of jingbian gas field are mainly coal derived gas generated from carboniferous permian coal measure strata with a small amount of oil derived gas generated from carboniferous permian marine terrigenous limestone

stable carbon isotope systematics of methane ethane and propane from low permeability hydrocarbon reservoirs abstract we have reassessed the stable carbon isotope systematics of methane c1 ethane c2 and propane c3 in more than 500 natural gas samples from low permeability hydrocarbon reservoirs around the world with the purpose of providing new tools for thermal maturity assessment of natural gas that is increasingly produced from such reservoir types world wide a low permeability reservoir resembles a semi closed system and we found that the stable carbon isotope distribution in c1 c3 alkanes differs partially from what has been previously observed in natural gas from conventional hydrocarbon accumulations e g c isotope distributions dominated by rayleigh distillation and kinetic isotope effects in a low permeability reservoir isotope exchange may play a more prominant role in the carbon isotope distribution driving the system towards an even isotopic distribution eid of 6 between methane and ethane and ethane and propane at ro of 1 5 at higher maturity ethane and propane depleted in 13c are formed as a consequence of thermal cracking of wet gas components and possibly free radical decomposition polymerization reactions which leads to the occurrence of isotope reversals 13cc2

barnett shale gas production fort worth basin issues and discussion newark east barnett shale field fort worth basin texas is currently the most productive gas field in texas in terms of daily production and is growing at an annual rate of more than 10 however despite the fact that the barnett play has been studied intensely by very capable geologists and engineers from several companies over a period of many years there continues to be several misunderstandings concerning fundamental factors controlling the success of the barnett play of north texas barnett gas production is poorer in areas near faults and structural flexures anticlines and synclines fractures which are most abundant in these structural settings are detrimental to barnett production open natural fractures are rare in the barnett and have little or nothing to do with barnett productivity in areas where barnett shale is thermally mature with respect to gas generation it is slightly overpressured about 0 52 psi ft 11 76 kpa m limestone beds within the barnett formation are the product of debris flows that originated on a carbonate shelf to the north of the present basin center it appears that the barnett can be used as an exploration model for other basins especially analogous basins of the ouachita trend the history of the development of the barnett reservoir in north texas provides an excellent example of how persistence can lead to success in nonconventional gas plays

geochemistry of the extremely high thermal maturity longmaxi shale gas southern sichuan basin abstract the marine shale of the silurian longmaxi formation in southern sichuan basin china is characterized by its huge thickness 100 600 m high toc values 0 35 18 4 favorable types of organic matter i and ii1 high ro values 1 8 4 2 abundant brittle minerals average 56 3 and strong gas generation intensity particularly its bottom section which has toc 2 and thickness of 20 70 m has recently been a main target for shale gas exploration and development geochemical parameters of 13 gas samples from longmaxi shale from 10 wells were analyzed in this study wetness of the gas molar fraction of ethane through pentanes in total gaseous hydrocarbon is only 0 24 0 70 making the longmaxi shale gas among the driest in the world carbon isotopic compositions of the alkane gases from longmaxi shale are characterized by 13c1 13c2 13c3 with the most positive 13c1 values in the world a positive relationship was observed between its 13c1 and 13c2 values reflecting the extremely high thermal maturity of the source rock 2hch4 values range from 140 to 151 and the 2hc2h6 values range from 130 to 173 the hydrogen isotopic compositions were mainly characterized by 2hch4

lithologic and tectonic controls on bedrock channel form at the northwest himalayan front 1 recognition that channel form reflects a river s ability to erode rock and transport material has spawned stream power models that estimate incision patterns by approximating energy dissipation within a channel these models frequently assume that channel width scales as a power law with drainage area partly because drainage area is easily extracted from digital elevation models dems however this assumption is often confounded by local variations in rock strength and rock uplift rate that can cause channel constriction downstream here we investigate the morphological response to spatial changes in rock strength and rock uplift rate of 10 bedrock channels traversing the mohand range along the northwest himalayan front we present a new method to continuously measure and compare channel width slope and other hydraulic parameters that integrate satellite imagery and dem analysis our method corrects for an 13 overestimation of average channel gradient from a 90 m resolution dem that arises from short circuits of fine scale meanders we find that channels 1 narrow 1 km upstream from knickpoints formed by an increase in rock strength 2 adjust laterally more than vertically in response to downstream decreases rock erodibility and uplift rate and 3 meander where shear stresses are high and channel widths are low we attribute these results to a high ratio of sediment supply to transport capacity which enhances lateral erosion relative to vertical incision our results suggest that substrate strength and sediment supply substantially influence channel form and that channel width should be explicitly measured when interpreting tectonic signals from bedrock channel morphology

geochemical characteristics and origin of natural gas from wufeng longmaxi shales of the fuling gas field sichuan basin china abstract as the first giant shale gas field in china the fuling gas field has recently been regarded as one of the most important regions for natural gas exploration and production in the sichuan basin however the origin of natural gas from upper ordovician wufeng and the bottom of lower silurian longmaxi wl shales in the fuling gas field is poorly understood to limit a comprehensive understanding of gas generation accumulation and exploration in this work based on molecular and stable carbon isotopic composition of a total of 24 gas samples from five shale gas wells in the fuling field we analyzed the geochemical characteristics and gas origin and discussed the cause for the geochemical anomalies carbon isotopic reversals molecular composition results show that gases from the fuling gas field are dry and mainly composed of methane 97 9 98 9 with a very low level of ethane c2h6 propane c3h8 and non hydrocarbon gases mainly co2 and n2 these dry gases are classified as oil associated gas and mainly derived from secondary cracking due to the lack of gas samples across a maturation gradient from immature to late mature the wl gases in the fuling field show an unclear evolution trend between the 13c2 and wetness values however all these samples are located in the isotopic reversal zone carbon isotopes of gaseous alkanes clearly display full isotopic reversals 13c1 13c2 13c3 which is indicative of a relatively high thermal maturity and consistent with the measured vitrinite reflectance and modeled values 3 0 ro the observed complete carbon isotopic reversals in the wl gases are caused by a combination of several mechanisms in which isotope exchange at high temperature is the primary controlling factor other secondary factors include rayleigh type fractionation of c2h6 and c3h8 secondary cracking and gas diffusion mixing of gases at different thermal maturity levels

estimation of discharge from three braided rivers using synthetic aperture radar satellite imagery potential application to ungaged basins analysis of 41 ers 1 synthetic aperture radar images and simultaneous ground measurements of discharge for three large braided rivers indicates that the area of active flow on braided river floodplains is primarily a function of discharge a power law correlation is found between satellite derived effective width we and discharge q where we is the water surface area within a braided reach divided by the reach length synthetic values of we and q generated from a cellular automata model of stream braiding display a similar power law correlation power functions that are fit through plots of we and q represent satellite derived rating curves that can subsequently be used to estimate instantaneous river discharge from space with errors ranging from tens to hundreds of cubic meters per second for ungaged rivers changes in relative discharge can be determined from satellite data alone to determine the shape and timing of annual flows in glacierized basins absolute discharge can probably be estimated within a factor of 2 more accurate estimates will require either 1 one or more ground measurements of discharge acquired simultaneously with a satellite image acquisition or 2 successful parameterization of known morphologic controls such as total sinuosity 5 p valley slope bank material and stability and braid channel hydraulic geometry values of total sinuosity 5 p derived from satellite imagery and field measurements from two rivers of braid channel width depth velocity water surface slope and bed material grain size indicate that while the shape of satellite derived we q rating curves may be influenced by all of these variables the sensitivity of flow area to changing discharge is most dependent upon the degree of braiding efforts to monitor river discharge from space will be most successful for intensely braided rivers with high values of total sinuosity subsampling of existing daily discharge records from the iskut river suggests that satellite return times of about 1 week are sufficient for approximating the shape and timing of the seasonal hydrograph in large glacierized basins although errors are large the presented technique represents the only currently available way to estimate discharge in ungauged braided rivers

carbon isotopic fractionation by desorption of shale gases abstract geochemical studies of shale gas and conventional reservoirs within the triassic yanchang formation of xiasiwan and yongning field ordos basin show that methane is isotopically depleted in 13 c as compared to 13 c 1 calculated by the ro based on the relationship between 13 c 1 and ro geochemical fractionation during the adsorption desorption process of shale system may play a significant part in influencing 13 c 1 values of shale gas two shale core samples from confined coring of the yanchang formation were adopted segmented desorption experiments to examine this phenomenon the results show that the 13 c 1 of desorbed gas changes little in the first few phases of the experiments at low desorption levels but become less negative rapidly when the fraction of desorbed methane exceeds 85 the desorption process for the last 15 fraction of the methane from the shale samples shows a wide variation in 13 c 1 from 49 to 33 9 moreover 13 c 1 of all desorbed methane from the shale samples is substantially depleted in 13 c than that calculated by ro according to stahl and carey s 13 c 1 ro equation for natural gas generated from sapropelic organic matter this shows some gases with isotopically enriched in 13 c cannot be desorbed under the temperature and pressure conditions of the desorption experiments this observation may be the real reason for the 13 c 1 of shale gases and conventional reservoirs becomes more negative in xiasiwan and yongning fields ordos basin the magnitude of the deviation between the 13 c 1 of shale gas and that calculated by ro may be related to the adsorption capacity of shale or the proportion of absorbed gases in this way we may be able to evaluate the relative adsorption capacity of shale in geological conditions by 13 c 1 of the shale gas or by 13 c 1 of conventional gas which generated by the shale with certainty the 13 c 1 of conventional gas in dingbian and yingwang fields have no deviation because the toc value of the hydrocarbon source rock is relatively low

predicting the proportion of free and adsorbed gas by isotopic geochemical data a case study from lower permian shale in the southern north china basin sncb abstract the alternating marine terrigenous shale facies of the lower permian taiyuan p 1 t formation and the lower permian shanxi p 1 s formation in the north margin of the southern north china basin sncb are characterized by their high toc values 1 76 5 09 types ii and iii organic matter and high ro values 3 0 geochemical parameters of 12 gas samples from the lower permian shale formations from well weican 1 were analyzed in this study the gases are dominated by methane with small amounts of ethane without propane and butane wetness of the gas is only 0 25 0 58 reflecting extremely high maturity of the source rock the 13 c 1 values range from 31 6 to 26 8 and the 13 c 2 values range from 35 9 to 33 2 the 2 h ch4 values range from 221 1 to 187 furthermore carbon isotopic compositions of the alkane gases from the lower permian shale are characterized by 13 c 1 13 c 2 this indicates that the gases released from permian shale are of thermogenic origin and mostly sourced from the continental shale and coal measures with minor contribution from oil cracked gas from marine mudstones geochemical fractionation during the adsorption desorption process of the shale system may play a significant part in influencing 13 c 1 values of shale gas the results show that the 13 c 1 becomes heavier with increasing degree of gas desorption based on isotope fractionation during desorption of gas in shales an equation was established to estimate the proportion of free and adsorbed gas in shales using 13 c 1 of shale gas in comparison with other equations this equation is based on the direct data of gas desorption experiment to avoid the adsorbed gas content often exhibit maxima from excess sorption isotherms experiment this method provides efficient way to understand the gas storage behavior in shales and broaden the application of gas isotope

quantitative evaluation of toc organic porosity and gas retention distribution in a gas shale play using petroleum system modeling application to the mississippian barnett shale abstract shale reservoirs have not benefited from advanced modeling tools to the extent of conventional resources thus an approach is proposed to integrate key parameters such as total organic carbon toc content methane adsorption and organic porosity in a basin simulator original toc has an impact on both gas generated volume and gas retention within source rocks the conversion of organic matter into hydrocarbons also creates additional intraparticle kerogen porosity in which oil and gas can be stored in this work a method is proposed to calculate the evolution of toc organic porosity and gas retention capacity free versus adsorbed through time in shale gas by means of petroleum system modeling gas adsorption potential on organic material is calculated using a langmuir model which accounts for pressure temperature and remaining solid toc organic porosity is calculated as the result of the change of the organic matter from solid immature kerogen to less dense fluid hydrocarbons during thermal maturation the method is tested on a 3d basin model of the mississippian barnett shale in texas usa the computed organic porosity varies from 0 in immature zones to a maximum of 4 of rock volume in organic rich and mature zones computed retained methane in the lower barnett shale ranges between 20 and 60 scf t from 1 to nearly 3 kg m3 and is mainly concentrated in mature areas of the basin simulated results are consistent with available barnett shale data possible effects of assumptions made in the approach and perspectives are discussed

origin of gaseous hydrocarbons noble gases carbon dioxide and nitrogen in carboniferous and permian strata of the distal part of the polish basin geological and isotopic approach abstract sixteen natural gas samples collected from pennsylvanian and permian rotliegend and zechstein limestone strata of the distal part of the polish basin in wielkopolska and lower silesia were analysed for molecular composition and stable carbon isotope composition of hydrocarbons ch 4 c 2 h 6 c 3 h 8 n c 4 h 10 and i c 4 h 10 and co 2 stable hydrogen isotope composition of methane stable nitrogen isotope composition of n 2 and stable isotope composition of noble gases he ne ar kr and xe thirteen of analysed hydrocarbon gases reveal complete 13 c ch 4 13 c c 2 h 6 13 c c 3 h 8 and partial inversed isotopic trends from methane to propane thus they have a very complicated generation migration and accumulation history and range of their source rock horizons two source rock horizons occur ne from wolsztyn ridge they contain mixed types iii ii and ii iii kerogens of pennsylvanian age and mississippian and or devonian age respectively one source rock horizon occurs sw from wolsztyn ridge it contains type iii and mixed type iii ii kerogens of pennsylvanian age the kerogens in all source rock horizons generated gaseous hydrocarbons at two separate maturity stages about 0 5 to 0 8 in vitrinite reflectance scale at the first maturity stage and over 1 3 in vitrinite reflectance scale at the second maturity stage high concentrations of he in analysed gases are mostly a product of decay of u and th enriched in crustal materials a small contribution of he and ne of mantle origin to the gas reservoirs was inferred radiogenic 4 he 40 ar ratios are higher than the average production rate ratio of about 5 for crustal materials which might have been caused by a selective supply of lighter he through crustal rocks surrounding the gas reservoirs or higher u th k ratio than the crustal average co 2 from analysed gases was mainly generated during thermogenic processes of transformation of organic matter although some gases can contain components from endogenic processes and from thermal destruction of zechstein limestone and probably precambrian carbonates n 2 was mainly generated during thermal transformation of organic matter and had a large component released from nh 4 rich illites very high n 2 40 ar for the gases might be caused by accelerated thermogenic production of n 2 under the condition of high heat flux from volcanic activity at late pennsylvanian and early permian age deep seated faults mainly framing the wolsztyn ridge perform important role in migration and mixed in different proportions of noble gases originated from upper mantle and from mineralisation by radioactive minerals their fault surfaces and occurrence of pennsylvanian lower permian volcanites in crust as well as hydrocarbon gases co 2 and n 2 also from thermal destruction of nh 4 rich illites from gas generation kitchens of source rock horizons to the traps

unique chemical and isotopic characteristics and origins of natural gases in the paleozoic marine formations in the sichuan basin sw china isotope fractionation of deep and high mature carbonate reservoir gases abstract large quantities of natural gases have recently been discovered in the marine carbonate formations in the sichuan basin southern china the origins and isotopic compositions of the gases are poorly understood and highly controversial we examined the chemical and isotopic compositions of the carbonate reservoir gases in marine formations from the sinian to lower triassic as well as shale gas from the silurian and cambrian formation in the sichuan basin it is found that the carbon isotopes of the carbonate reservoir gases had been evolved through three stages corresponding to pre rollover rollover and post rollover in the plot of 13c2 versus wetness which is consistent with that found in shale gas by tilley and muehlenbachs 2013 the unique carbon isotopic compositions indicate that both kerogen and oil cracking gas have contributed to the accumulation of the carbonate reservoir gases in the sichuan basin a mixing of two thermogenic gases with different maturities can cause the 13c reversal between methane and ethane which is commonly observed in the carbonate reservoir gases in the carboniferous permian and triassic formations and the shale gas in the silurian and cambrian formations in the sichuan basin we established two mixing models for quantitatively determining the contribution of each type gas for the natural gases in different formations kinetic extrapolation based on thermal history of the anyue gas field demonstrates that ethane cracking indeed occurred in the deep reservoir formations which may explain the disappearance of the 13c reversal for methane and ethane in the carbonate reservoir gases in the post rollover zone it is proposed that organic inorganic interactions may be responsible for the presence of d isotope rollover for methane in carbonate reservoir gases with ultra high maturity the organic inorganic interactions include thermal reactions between water and residual organic matters or carbons and hydrogen isotope exchange between water and methane and their mechanism needs further investigations in future

in reservoir mixing of mantle derived co2 and metasedimentary ch4 n2 fluids noble gas and stable isotope study of two multistacked fields pannonian basin system w hungary abstract several multistacked gas fields located in very different parts of hungary display a large variation in their gas composition the shallow position of the mantle beneath the basement of the pbs is responsible for the high heat flux it facilitates that the co 2 intensely released from the ascending upper mantle derived melts could reach the basin system in this work the results of a geochemical study of the main components and noble gases of the multistacked repcelak co 2 hc n 2 and mihalyi co 2 fields are presented and discussed the vertical variations of gas composition in the repcelak and mihalyi fields fit well with in reservoir mixing of two end members a mantle related magmatic co 2 fluid and a n 2 rich hc gas fluid of crustal origin however it is very likely that other processes modified to some extent the gas composition of the two fields carbon isotopic composition of the co 2 of the samples studied agrees with both the carbonate decomposition and mantle degassing origins it is very likely that the marked difference in helium isotopic composition between the neighbouring repcelak and mihalyi fields also reflects this heterogeneity

origin and enrichment factors of natural gas from the lower silurian songkan formation in northern guizhou province south china abstract the northern guizhou area located near the southwestern margin of the yangtze block and south of the sichuan basin is a promising area for shale gas exploration and development the discovery of a natural gas accumulation in the lower silurian songkan formation in the study area is the first discovery of natural gas in this stratum in china marking an exciting breakthrough in natural gas exploration in northern guizhou area this paper presents an investigation of this accumulation using gas geochemistry including gas composition carbon and hydrogen isotopes in context with geological information available for the study area our results indicate that the natural gas accumulation in songkan formation is probably sourced from the lower silurian wufeng longmaxi shale the 13 c ch 4 values range from 33 9 to 33 2 the 13 c c 2 h 6 values range from 37 0 to 36 2 and the 2 h ch 4 values range from 157 to 144 these results indicate that the gases are of thermogenic origin and are oil derived furthermore isotopic rollovers seen in the natural gas is similar to that seen in the natural gas from the local wufeng longmaxi shale which is identified as carbon exchange at high temperature the 13 c co 2 values range from 20 8 to 17 1 suggesting that carbon dioxide was mainly generated by thermogenic processes the fracture investigation indicates that the large development of horizontal fractures in calcareous mudstone is one of the reasons for the high yield of natural gas in songkan formation the petrophysical parameters suggest that limestone with low porosity and permeability effectively prevents natural gas escaping and seals natural gas into calcareous mudstone with horizontal fractures

unconventional shale gas systems the mississippian barnett shale of north central texas as one model for thermogenic shale gas assessment shale gas resource plays can be distinguished by gas type and system characteristics the newark east gas field located in the fort worth basin texas is defined by thermogenic gas production from low porosity and low permeability barnett shale the barnett shale gas system a self contained source reservoir system has generated large amounts of gas in the key productive areas because of various characteristics and processes including 1 excellent original organic richness and generation potential 2 primary and secondary cracking of kerogen and retained oil respectively 3 retention of oil for cracking to gas by adsorption 4 porosity resulting from organic matter decomposition and 5 brittle mineralogical composition the calculated total gas in place gip based on estimated ultimate recovery that is based on production profiles and operator estimates is about 204 bcf section 5 78 10 9 m 3 1 73 10 4 m 3 we estimate that the barnett shale has a total generation potential of about 609 bbl of oil equivalent ac ft or the equivalent of 3657 mcf ac ft 84 0 m 3 m 3 assuming a thickness of 350 ft 107 m and only sufficient hydrogen for partial cracking of retained oil to gas a total generation potential of 820 bcf section is estimated of this potential approximately 60 was expelled and the balance was retained for secondary cracking of oil to gas if sufficient thermal maturity was reached gas storage capacity of the barnett shale at typical reservoir pressure volume and temperature conditions and 6 porosity shows a maximum storage capacity of 540 mcf ac ft or 159 scf ton

a morphology independent methodology for quantifying planview river change and characteristics from remotely sensed imagery abstract remotely sensed imagery of rivers has long served as a means for characterizing channel properties and detection of planview change in the last decade the dramatic increase in the availability of satellite imagery and processing tools has created the potential to greatly expand the spatial and temporal scale of our understanding of river morphology and dynamics to date the majority of gis and automated analyses of planview changes in rivers from remotely sensed data has been developed for single threaded meandering river systems these methods have limited applicability to many of the earth s rivers with complex multi channel planforms here we present the methodologies of a set of analysis algorithms collectively called spatially continuous riverbank erosion and accretion measurements scream scream analyzes planview river metrics regardless of river morphology these algorithms quantify both the erosion and accretion rates of riverbanks from binary masks of channels generated from imagery acquired at two time periods additionally the program quantifies the area of change between river channels and the surrounding floodplain and area of islands lost or formed between these two time periods to examine variations in erosion rates in relation to local channel attributes and make rate comparisons between river systems of varying sizes the program determines channel widths and bank curvature at every bank pixel scream was developed and tested on rivers with diverse and complex planform morphologies in imagery acquired from a range of observational platforms with varying spatial resolutions validation and verification of scream generated metrics against manual measurements show no significant measurement errors in determination of channel width erosion and bank aspects scream has the potential to provide data for both the quantitative examination of the controls on erosion rates and for the comparison of these rates across river systems ranging broadly in size and planform morphology

understanding of hydraulic properties from configurations of stochastically distributed fracture networks a systematic investigation of the effect of configurations of stochastically distributed fracture networks on hydraulic behaviour for fractured rock masses could provide either quantitative or qualitative correlation between the structural configuration of the fracture network and its corresponding hydraulic behaviour and enhance our understanding of appropriate application of groundwater flow and contaminant transport modelling in fractured rock masses in this study the effect of block sizes intersection angles of fracture sets standard deviations of fracture orientation and fracture densities on directional block hydraulic conductivity and representative elementary volume is systematically investigated in two dimensions by implementing a numerical discrete fracture fluid flow model and incorporating stochastically distributed fracture configurations it is shown from this investigation that the configuration of a stochastically distributed fracture network has a significant quantitative or qualitative effect on the hydraulic behaviour of fractured rock masses compared with the deterministic fracture configurations that have been extensively dealt with in a previous study this investigation is expected to be more practical and adequate since fracture geometry parameters are inherently stochastically distributed in the field moreover the methodology and approach presented in this study may be generally applied to any fracture system in investigating the hydraulic behaviours from configurations of the fracture system while establishing a bridge from the discrete fracture network flow modelling to equivalent continuum modelling in fractured rock masses copyright 2007 john wiley sons ltd

mixing of thermogenic natural gases in northern appalachian basin stable isotopic studies were undertaken to investigate the origin of 20 oil associated and non associated gases from western and central new york state in the northern appalachian basin gas wetness c2 c5 c1 c5 methane dgr13c and methane dgrd values range from 0 8 to 26 9 47 9 to 30 7 pmil and 305 to 143 pmil respectively corresponding ethane and propane dgr13c values range from 40 9 to 32 0 pmil and 34 9 to 27 9 pmil these data are interpreted to indicate a thermogenic origin with source rock maturities ranging from early mature equivalent vitrinite reflectance ro approximately 0 5 to post mature equivalent ro 2 0 inferred gas maturities generally in rease with increasing reservoir age from late to middle devonian marcellus and overlying rocks middle devonian to latest silurian oriskany onondaga akron silurian lockport herkimer medina to ordovician queenston and black river oil and gas in many late to middle devonian reservoirs may have migrated from interbedded organic rich shales in other reservoirs particularly those of ordovician and silurian age unusual isotopic reversals methane dgr13c ethane dgr13c suggest that gas generated locally from equivalent age rocks within the oil window mixed with post mature gas migrated from deeply buried sources to the south and southeast the post mature gas was probably sourced from middle to late ordovician shales regional migration of middle ordovician gas may have occurred along the middle ordovician knox unconformity gas was presumably channeled into overlying silurian and devonian reservoirs along faults and fractures

geochemistry and origin of natural gas in the petroliferous mahu sag northwestern junggar basin nw china carboniferous marine and permian lacustrine gas systems abstract the mahu sag located in the northwestern junggar basin of nw china is a renowned carboniferous marine permian lacustrine hydrocarbon depocenter that in theory could host both oil and gas however as ongoing hydrocarbon exploration and production are focused solely on oil few gas prospects have been discovered in this paper we discuss the possible occurrence of natural gas deposits based on a comprehensive study of gas geochemistry including gas composition carbon isotopes and compositions of light hydrocarbons c5 c7 and biomarkers in retrograde condensates combined with geological information available for the study area our results indicate that three types of natural gas occur in the region a sapropelic type gas derived from the lower permian fengcheng formation p1f a humic type gas sourced from carboniferous strata c and the overlying lower permian jiamuhe formation p1j and a humic type gas derived from the middle permian lower wuerhe formation p2w the p1f sourced sapropelic type gas accumulated during at least two distinct periods of time yielding low maturity oil associated gases and mature to high maturity kerogen oil cracking gases the carboniferous and p1j sourced humic type gases are mainly high maturity to over mature kerogen oil cracking gases without obvious geochemical evidence for a multi stage accumulation the p2w sourced gas is a mature humic type gas of these three types of gas the former two have the potential to form significant gas deposits and constitute valid exploration targets making the mahu sag a prospective area for gas exploration favorable areas for gas occurrence include deep anticlines hosting both kerogen and oil cracking gases the inferred exploration targets occur at significant depths which is why little drilling has been undertaken in these areas and major gas discoveries have yet to be made

sedimentary and residual gas geochemical characteristics of the lower cambrian organic rich shales in southeastern chongqing china to study the sedimentary environment of the lower cambrian organic rich shales and isotopic geochemical characteristics of the residual shale gas 20 black shale samples from the niutitang formation were collected from the youyang section located in southeastern chongqing china a combination of geochemical mineralogical and trace element studies has been performed on the shale samples from the lower cambrian niutitang formation and the results were used to determine the paleoceanic sedimentary environment of this organic rich shale the relationships between total organic carbon toc and total sulfur ts content carbon isotope value 13corg trace element enrichment and mineral composition suggest that the high toc niutitang shale was deposited in an anoxic environment and that the organic matter was well preserved after burial stable carbon isotopes and biomarkers both indicate that the organic matter in the niutitang black shales was mainly derived from both lower aquatic organisms and algaes and belong to type i kerogen the oil prone niutitang black shales have limited residual hydrocarbons with low values of s2 ih and bitumen a the carbon isotopic distribution of the residual gas indicate that the shale gas stored in the niutitang black shale was mostly generated from the cracking of residual bitumen and wet gas during a stage of significantly high maturity one of the more significant observations in this work involves the carbon isotope compositions of the residual gas c1 c2 and c3 released by rock crushing a conventional 13c1 13c2 trend was observed and most 13c2 values of the residual gases are heavier than those of the organic matter om in the corresponding samples indicating the splitting of ethane bonds and the release of smaller molecules leading to 13c enrichment in the residual ethane

geochemical characteristics of gases from the largest tight sand gas field sulige and shale gas field fuling in china abstract this study performed a detailed geochemical analyses of the components stable carbon isotopes of alkane gas and co2 stable hydrogen isotopes of alkane gas and helium isotopes of reproducing gas from the largest tight gas field sulige and shale gas fuling field in china the comparative study shows that tight gas from the sulige gas field in the ordos basin is of coal derived origin which is characterized by a positive carbon and hydrogen isotopic distribution pattern 13c1 13c2 13c3 13c4 2h1 2h2 2h3 i e the carbon and hydrogen isotopes increase with increasing carbon numbers carbon dioxide from this field are of biogenic origin and the helium is crust derived shale gas from the fuling shale gas field belongs to oil derived gas which has complete carbon and hydrogen isotopic reversal of secondary alteration origin 13c1

on the use of srtm and altimetry data for flood modeling in data sparse regions the growing availability of remotely sensed data has fostered the implementation of hydraulic modeling in poorly gauged regions however these applications suffer the lack of knowledge of river bathymetry which cannot be directly inferred from satellite instruments this study explores the possibility to set up calibrate and validate a hydrodynamic model which geometry is based on global and freely available satellite data first the study tests two different procedures for inferring the river bathymetry under the water surface level second focusing on a po river stretch of 140 km northern italy the study further assesses the suitability of spaceborne topographic and remotely sensed altimetry data i e ers 2 and envisat for implementing and calibrating hydrodynamic models referring to 90 m srtm shuttle radar topography mission digital elevation model for the representation of the riverbed morphology the work analyzes the performances of different 1 d numerical models which cross sections are modified according to two approaches 1 channel bankfull depth cb and 2 slope break sb approach the calibration and validation processes are performed by referring to extended altimetry time series 16 years of data while the accuracy and trustworthiness of 1 d models are tested with reference to a quasi 2 d model based on detailed geometry data results show that both cb and sb approaches enhance the performance of srtm based models in particular the sb approach is completely based on satelliteborne data and shows nash sutcliffe efficiency mae and rmse values similar to those obtained with the benchmark model

an unusual occurrence of light hydrocarbon gases in a well offshore northeast palawan island the philippines abstract sediments from a well offshore northeast palawan island the philippines appear to contain light hydrocarbons of possible abiogenic origin this observation is based on stable carbon isotope ratios organic petrography and chemical and geological considerations

a simple global river bankfull width and depth database 1 hydraulic and hydrologic modeling has been moving to larger spatial scales with increased spatial resolution and such models require a global database of river widths and depths to facilitate accurate river flow routing hydraulic geometry relationships have a long history in estimating river channel characteristics as a function of discharge a simple near global database of bankfull widths and depths along with confidence intervals was developed based on hydraulic geometry equations and the hydrosheds hydrography data set the bankfull width estimates were evaluated with widths derived from landsat imagery for reaches of nine major rivers showing errors ranging from 8 to 62 correlation of 0 88 although it was difficult to verify whether the satellite observations corresponded to bankfull conditions bankfull depth estimates were compared with in situ measurements at sites in the ohio and willamette rivers producing a mean error of 24 the uncertainties in the derivation approach and a number of caveats are identified and ways to improve the database in the future are discussed despite these limitations this is the first global database that can be used directly in hydraulic models or as a set of constraints in model calibration

geochemical characteristics and origins of natural gas in the zhu iii sub basin pearl river mouth basin china abstract the zhu iii sub basin is an important petroliferous region in the south china sea where hydrocarbon distribution shows strong heterogeneity with oil primary produced from the wenchang b depression and gases from the wenchang a depression however a mixture of oil and gases are produced from the surrounding qionghai and shenhu uplifts the origin generation history and migration pathway of oil have been intensively studied but no study have been done directly on the gas which restricts future petroleum exploration in this study natural gas molecular compositions were measured on 46 samples stable carbon isotopic composition were measured on 39 samples and light hydrocarbon composition were measured on 30 samples results indicate that natural gases in the zhu iii sub basin are mainly composed of hydrocarbon gases with abundant co2 and n2 the hydrocarbon gases are all thermogenic gases which are mainly derived from the oligocene enping formation e3e 35 30 ma the contribution of the eocene wenchang formation e2w 56 35 ma to natural gases increases from the wenchang a depression to the south boundary fault sbf and surrounding uplifts this is caused by the early generated natural gases with more contribution from the e2w and dissolved in oils that migrated to the surrounding qionghai and shenhu uplifts natural gases and oil in the surrounding uplifts and near the sbf therefore avoided secondary cracking due to the high gas migration rate through the sbf and lateral sandstone carrier beds whereas natural gases in the wenchang a depression mainly originated from the secondary cracking of oil the equivalent vitrinite reflectance values of source rocks when the natural gases were generated varied from 0 6 to 1 5 based on carbon isotope differences between hydrocarbons indicating mature to high mature stage co2 with abundance less than 10 mainly originated from organic matter decomposition co2 with abundance more than 15 was sourced from the deep mantle and crust and mainly concentrated in the deep layers near the sbf which cuts into the basement n2 is probably the product of in situ reservoir alteration such as biodegradation in shallower layers our study on the geochemical characteristics and origins of the natural gas will enable a better understanding of petroleum system in the zhu iii sub basin and provide theoretical basis for optimizing future petroleum exploration strategy detailed study on shallow layers in the qionghai and shenhu uplifts and deep layers near the sbf are needed because exploration risks are relatively high in these plays

isotope reversals and universal stages and trends of gas maturation in sealed self contained petroleum systems abstract isotope geochemistry is now a tool for shale gas exploration largely due to the association of isotope reversals with mature highly productive shale gas its utility however depends on an understanding of the isotope systematics for the particular region of interest as well as for shale gas maturation in general this paper reviews and re examines isotope data from four published papers that include shale gas from the barnett and fayetteville shales rodrigez and philp 2010 zumberge et al 2012 and gas from fractured reservoirs in the appalachians burruss and laughrey 2010 and the foothills of the western canada sedimentary basin wcsb tilley et al 2011 new shale and tight sandstone gas data are also presented for the wcsb comparisons of these data show that the progression through three stages of gas maturation pre rollover zone rollover zone and post rollover zone is universal in sealed self contained petroleum systems and that each zone has characteristic isotopic relationships and trends that are seen in all areas examined gases in the pre rollover zone are isotopically normal 13 c methane 13 c ethane 13 c propane unless mixing of gases from different sources has occurred in the rollover zone 13 c ethane and 13 c propane become progressively more negative as 13 c methane becomes less negative and ethane and methane are reversed 13 c ethane 13 c methane only towards the most mature portion of the rollover zone at the beginning of the post rollover zone 13 c ethane 13 c methane but as 13 c ethane and 13 c propane become increasingly less negative at varying rates ethane and propane may or may not be reversed with respect to each other at the highest maturities 2 h methane in gases of the post rollover zone approaches isotopic equilibrium with local formation water generally becoming more negative with increasing maturity correct assignment of maturity stage could be of importance because the rollover zone may represent the peak of high productivity shale gas whereas the post rollover zone may represent a decline in productivity burruss and laughrey 2010

shale gas desorption behavior and carbon isotopic variations of gases from canister desorption of two sets of gas shales in south china abstract four shale samples from the lower silurian longmaxi formation and the lower cambrian shuijingtuo formation in the eastern part of chongqing sw china were subjected to canister desorption experiments at reservoir and elevated temperatures up to 90 c to investigate shale gas release behaviors and their variations in chemical and isotopic compositions of desorbed gases both the ratios of gas released at reservoir temperature to the total desorbed gas at reservoir and elevated temperatures and the desorption rates suggest that the longmaxi shale gas is more easily released than the shuijingtuo shale gas scanning electron microscope sem observation along with low temperature co2 and n2 adsorption results suggests that organic matter hosted pores with diameters of 2 100 nm are rich in the longmaxi shales whereas well developed micropores

gas isotope reversals in fractured gas reservoirs of the western canadian foothills mature shale gases in disguise isotopically reversed gases 13c methane 13c ethane 13c propane occur in fractured mixed clastic carbonate reservoirs of the permian and the triassic in the foothills at the western edge of the western canada sedimentary basin wcsb the 13c methane values 42 to 24 gas dryness and organic maturity ro 2 2 are indicative of mature gases and gas maturity generally increases with reservoir age and from the southeast to the northwest the 13c ethane values range from 44 to 25 with the less negative values in isotopically normal gases to the northeast of the gas fields we studied to explain the gas isotope reversals observed in the wcsb foothills we adopt the concept of a closed system shale in which simultaneous cooking of kerogen oil and gas yields gas with light 13c ethane and heavy 13c methane this gas was released from shales and trapped in fractured folds of brittle clastic carbonate rocks during deformation and thrust faulting of the laramide orogeny creating some of the most prolific gas pools these gases are actually mature shale gases local high abundances of h2s and co2 are most likely the products of thermochemical sulfate reduction tsr reactions in anhydrite rich interbeds and underbeds that admixed to the released shale gas during the tectonic event no evidence exists that tsr is responsible for the isotope reversals variations in 13c ethane are likely caused by local differences in thermal history the timing of gas release from shale and the timing of the fault and fold development less negative 13c ethane values resulting in isotopically normal gases to the northeast of the fields and in the underlying devonian carbonates likely reflect a more open shale system where the earliest generated gas was lost we suggest that isotopic reversals are restricted to closed system maturation and that their magnitude may be related to the relative volume of gas retained in shales

geochemical characteristics and isotopic reversal of natural gases in eastern kopeh dagh ne iran abstract natural gas samples from two gas fields located in eastern kopeh dagh area were analyzed for molecular and stable isotope compositions the gaseous hydrocarbons in both lower cretaceous clastic reservoir and upper jurassic carbonate reservoir are coal type gases mainly derived from type iii kerogen however enriched d values of methane implies presence of type ii kerogen related material in the source rock in comparison upper jurassic carbonate reservoir gases show higher dryness coefficient resulted through tsr while presence of c 1 c 5 gases in lower cretaceous clastic reservoir exhibit no tsr phenomenon carbon isotopic values indicate gas to gas cracking and tsr occurrence in the upper jurassic carbonate reservoir as the result of elevated temperature experienced prior to the following uplifts in last 33 37 million years the 13 c of carbon dioxide and 34 s of hydrogen sulfide in upper jurassic carbonate reservoir do not primarily reflect tsr as uplift related carbonate rock dissolution by acidic gases and reaction precipitation of light h 2 s have changed these values severely gaseous hydrocarbons in both reservoirs exhibit enrichment in c 2 gas member with the carbonate reservoir having higher values resulted through mixing with highly mature completely reversed shale gases it is likely that the uplifts have lifted off the pressure on shale gases therefore facilitated the migration of the gases into overlying horizons however it appears that the released gases during the first major uplift 33 37 million years ago have migrated to both reservoirs while the second migrated gases have only mixed with upper jurassic carbonate reservoir gases the studied data suggesting that economic accumulations of natural gas shale gases deeper than upper jurassic carbonate reservoir would be unlikely

empirical relationship between gas composition and thermal maturity in eagle ford shale south texas organic rich and carbonate rich eagle ford shale is a self sourced oil and gas reservoir with little alteration of gas chemistry as might be affected by petroleum expulsion and migration as such it provides an ideal natural laboratory to quantify the compositional variation of gases generated from oil prone type ii kerogen during thermal maturation the chemical composition of the gas released from rock crushing was conducted and integrated with rock eval pyrolysis to define the empirical relationship between gas compositional parameters and thermal maturity in this study from 10 wells in the eagle ford shale in south texas we collected 74 core samples having a range of thermal maturity the measured maximum temperature tmax values of hydrocarbons generated in rock eval pyrolysis range from 427 c to 494 c 800 f to 921 f and the calculated equivalent vitrinite reflectance roe values range from 0 51 to 1 73 based on tmax values total organic carbon content ranges from 0 3 to 8 53 with an average of 3 12 standard deviation of 1 77 burial depth is from 2989 6 to 13 827 3 ft 911 2 to 4214 6 m our results showed that gas composition in the eagle ford shale is mainly controlled by thermal maturity and three stages of gas generation are identified based on the c1 and c2 concentrations of the gases released by rock crushing from eagle ford shale core samples the three stages of gas generation correspond to the following processes of organic matter conversion 1 kerogen and bitumen thermal cracking to crude oil 2 bitumen and heavy crude oil thermal cracking to light oil and 3 light oil cracking to gas methane rich gas and an abundance of branched butane and pentane are generated in light oil cracking to gas resulting in high c1 c2 c1 c2 c3 i c4 n c4 and i c5 n c5 ratios increased cracking of normal alkanes such as n butane and n pentane occurs in the light oil cracking to gas empirical equations between gas compositional parameters and thermal maturity tmax or roe are obtained for oil prone type ii the c1 c2 c1 c2 c1 c2 c3 and i c4 n c4 ratios are the five best parameters for determining thermal maturity with an exponentially derived r2 value of 0 74 the composition of gas produced from the eagle ford shale following hydraulic fracturing is used to validate the empirical equations calculated thermal regime for the oil production based on the produced gas is located at the peak of oil generation and the beginning of light oil cracking to gas corresponding to tmax from 454 c to 464 c 849 f to 867 f or at an roe ranging from 1 01 to 1 19 empirical equations provide a basis for interpretation of mud gas logging data and produced gas composition

development of the global width database for large rivers river width is a fundamental parameter of river hydrodynamic simulations but no global scale river width database based on observed water bodies has yet been developed here we present a new algorithm that automatically calculates river width from satellite based water masks and flow direction maps the global width database for large rivers gwd lr is developed by applying the algorithm to the srtm water body database and the hydrosheds flow direction map both bank to bank river width and effective river width excluding islands are calculated for river channels between 60s and 60n the effective river width of gwd lr is compared with existing river width databases for the congo and mississippi rivers the effective river width of the gwd lr is slightly narrower compared to the existing databases but the relative difference is within 20 for most river channels as the river width of the gwd lr is calculated along the river channels of the hydrosheds flow direction map it is relatively straightforward to apply the gwd lr to global and continental scale river modeling

influence of retained bitumen in oil prone shales on the chemical and carbon isotopic compositions of natural gases implications from pyrolysis experiments abstract retained bitumen in oil prone source rocks has a significant impact on late gas generation but such influence is still poorly quantified because it is quite difficult to restore the bitumen content retained in a mature source rock in this study a suite of artificially matured samples were prepared from a moderate maturity shale sample to represent shales with different amount of retained bitumen these samples were then pyrolyzed in sealed gold tubes to investigate how the amount of retained bitumen affects the changes in chemical and carbon isotopic compositions of generated gases and the uncertainty of the evaluation of gas maturity and source identification the results indicate that the decrease in yields of hydrocarbon gases is proportional to the reduction of retained bitumen content however a progressive enrichment in heavier carbon isotope 13c of gaseous hydrocarbons occurs while less amount of bitumen is retained in shales this experimental observation partly explains the heterogeneity of methane carbon isotopes for shale gases that have identical thermal maturity levels although the amount of retained bitumen can significantly change the carbon isotopic ratios of individual gas 13c1 13c2 and 13c3 the difference in carbon isotopic composition between gaseous components such as ethane and methane 13c2 13c1 or propane and ethane 13c3 13c2 are not significantly affected and therefore these differential values can be potentially used as maturity indicators for overmature natural gases exhibiting no carbon isotopic reversals geochemical and carbon isotopic diagrams that are widely used for the identification of oil and kerogen cracking gases are also found to be affected by the retained bitumen content these results illustrate that it is necessary to take into account the retained bitumen content of shales when thermal maturity and genetic origin of natural gases derived from oil prone source rocks are being evaluated

a review of alkane gas geochemistry in the xujiaweizi fault depression songliao basin abstract a large suite 172 of gases from the yingcheng fm in the xujiaweizi fault depression has been studied chemically and isotopically the results show that they are mainly type iii kerogen coal type gas and have been generated and accumulated under the influence of hydrothermal fluids both measured and calculated vitrinite reflectance data show that they have been generated mainly at source maturity higher than 2 0 ro many gases show carbon isotopic reversals typically 13 c 1 13 c 2 and 13 c 2 13 c 3 the origin of carbon isotopic reversals is discussed in this paper and the results show that previous interpretations including a mixing and b the occurrence of abiogenic gases are incorrect based on iso butane n butane data wet gas cracking may have occurred but it is not the main cause of carbon isotopic reversals here we propose that a process of abiogenic polymerization of c 2 gases with methane is the main cause of the carbon isotopic reversals in this basin

the upper thermal maturity limit of primary gas generated from marine organic matters abstract elemental composition and chemical structure of 16 kerogen samples concentrated from marine source rocks with maturity levels ranging from 0 65 ro to 3 3 ro were determined pyrolysis experiments of seven samples selected from the 16 kerogen samples were conducted in a gold tube system to clarify the process and determine the upper thermal maturity limit for primary gas generation from marine organic matter om the variation of the h c atomic ratio of the marine om appears to evolve through three phases with increasing maturity including a drastic decreasing phase before 1 3 ro a moderate decreasing phase from 1 3 to 2 0 ro and a gradual decreasing phase above 2 0 ro the evolution of the chemical structure measured by ftir indicates that most oxygen containing functional groups in marine om appear to be released prior to 0 8 ro aliphatic groups were still detected in the sample with a maturity of 3 0 ro but disappeared in the sample with a maturity of 3 3 ro the variation of aliphatic groups vs aromatic rings i1 displays a similar three stage pattern as the variation of h c atomic ratio with increasing maturity a step by step heating method in kerogen pyrolysis experiments was adopted to preclude secondary gas generation the pyrolysis experimental results for samples with different maturities proved that generally the maximum yield of primary gas generated by the marine om was not more than 140 ml per gram of total organic carbon toc only 1 16 ml g toc of hydrocarbon gas was generated by the sample with the maturity of 3 3 ro thus it can be rationally inferred that the upper thermal maturity limit for gas generation from the marine om may be around 3 5 ro nevertheless the main maturity range for the primary gas generation is suggested to be below 2 0 ro the yield of primary gas generated at the maturity range above 2 0 ro takes up 10 of maximum yield of the primary gas generated by the marine om

limits of downstream hydraulic geometry adjustments to flow width depth and velocity in response to changes in discharge are commonly characterized by using downstream hydraulic geometry relationships the spatial limits of these relationships within a drainage basin have not been systematically quantified where the erosional resistance of the channel substrate is sufficiently large hydraulic driving forces presumably will be unable to adjust channel form data sets from 10 mountain rivers in the united states panama nepal and new zealand are used in this study to explore the limits of downstream hydraulic geometry relationships where the ratio of stream power to sediment size d 84 exceeds 10 000 kg s3 downstream hydraulic geometry is well developed where the ratio falls below 10 000 kg s3 downstream hydraulic geometry relationships are poorly developed these limitations on downstream hydraulic geometry have important implications for channel engineering and simulations of landscape change

cause of shale gas geochemical anomalies and mechanisms for gas enrichment and depletion in high maturity shales abstract this article reviews the abnormal characteristics of shale gases natural gases produced from organic rich shales and discusses the cause of the anomalies and mechanisms for gas enrichment and depletion in high maturity organic rich shales the reported shale gas geochemical anomalies include rollover of iso alkane normal alkane ratios rollover of ethane and propane isotopic compositions abnormally light ethane and propane 13 c values as well as isotope reversals among methane ethane and propane these anomalies reflect the complex histories of gas generation and associated isotopic fractionation as well as in situ mixing and accumulation of gases generated from different precursors at different thermal maturities a model was proposed to explain the observed geochemical anomalies gas generation from kerogen cracking at relatively low thermal maturity accounted for the increase of iso alkane normal alkane ratios and ethane and propane 13 c values normal trend simultaneous cracking of kerogen retained oil and wet gas and associated isotopic fractionation at higher maturity caused decreasing iso alkane normal alkane ratios lighter ethane and propane 13 c and corresponding conversion of carbon isotopic distribution patterns from normal through partial reversal to complete reversal relatively low oil expulsion efficiency at peak oil generation low expulsion efficiency at peak gas generation and little gas loss during post generation evolution are necessary for organic rich shales to display the observed geochemical anomalies high organic matter richness high thermal maturity high degrees of kerogen gas and oil gas conversions and late stage the stage of peak gas generation and post generation evolution closed system accounted for gas enrichment in shales loss of free gases during post generation evolution may result in gas depletion or even undersaturation total gas content lower than the gas sorption capacity in high maturity organic rich shales

methane cracking within shale rocks a new explanation for carbon isotope reversal of shale gas abstract shale gas with carbon isotope reversal 13cmethane 13cethane as a promising indicator for resource sweet spot tends to occur at high over maturity shales with high gas dryness index cmethane cmethane cethane 0 97 however the cause for this reversal is still controversial and remains an open question in the present work we propose methane cracking within high over matured shale rocks as one of the possible mechanisms to explain this reversal which will further enhance the knowledge about carbon isotope reversal of shale gas in order to validate this hypothesis methane pyrolysis experiments were carried out in closed gold tube system to investigate the mechanism of occurrence of carbon isotope reversal in shale gas from the pyrolysates the cracking of ch4 and the generation of higher number hydrocarbons like c2h4 c2h6 and c3h8 were detected the ch4 cracking and the subsequent formation of c2h6 led to the residual ch4 being enriched in 13c whereas the produced c2h6 is depleted in 13c based on our experimental results and the data analysis of 583 samples from shale gas reservoirs from different regions of the world we suggest that ch4 will be cracked and combined into c2h6 in high over matured shales when the contribution from methane derived c2h6 is sufficiently massive the commonly found order of 13cmethane 2 0 and a carbon isotope reversal will occur for the shale gas the barnett shale from fort worth basin usa as the application representative shale gas reservoir cover the evolution scope of the increase and subsequent decrease of 13cethane along with increase of 13cmethane and thus the beginning of the carbon isotope reversal

developing channel and floodplain dimensions with limited data a case study in the amazon basin this research builds on the concept of hydraulic geometry and presents a methodology for estimating bankfull discharge and the hydraulic geometry coefficients and exponents for a station using limited data only stage discharge and landsat imagery the approach is implemented using 82 streamflow gauging locations in the amazon basin using the estimated values for the hydraulic geometry relations bankfull discharge discharge data above bankfull and upstream drainage area at each site relationships for estimating channel and floodplain characteristics as a function of drainage area are developed specifically this research provides relationships for estimating bankfull discharge bankfull depth bankfull width and floodplain width as a function of upstream drainage area in the amazon basin intended for providing reasonable cross section estimates for large scale hydraulic routing models the derived relationships are also combined with a high resolution drainage network to develop relationships for estimating cumulative upstream channel lengths and surface areas as a function of the specified minimum channel width ranging from 2 m to 1 km i e threshold drainage areas ranging from 1 to 431 000 km2 at the finest resolution i e all channels greater than 2 m or a threshold area of 1 km2 the amazon basin contains approximately 4 4 million kilometers of channels with a combined surface area of 59 700 km2 the intended use of these relationships is for partitioning total floodable area channels versus lakes and floodplain lakes obtained from remote sensing for biogeochemical applications e g quantifying co2 evasion in the amazon basin copyright 2011 john wiley sons ltd

patterns of river width and surface area revealed by the satellite derived north american river width data set as hydraulic hydrologic and biogeochemical models evolve toward greater spatial resolution and larger extent robust morphometric data sets are essential to constrain their results here we present the landsat derived north american river width narwidth data set the first fine resolution continental scale river centerline and width database narwidth contains measurements of 2 4 105 km of rivers wider than 30 m at mean annual discharge we find that conventional digital elevation model derived width data sets underestimate the abundance of wide rivers to calculate the total surface area of north american rivers we extrapolate the strong observed relationship between river width and total surface area at different river widths r2 0 99 for 100 2000 m widths to narrower rivers and streams we conservatively estimate the total surface area of north american rivers as 1 24 0 15 0 39 105 km2 1 confidence intervals values 20 15 38 greater than previous estimates used to evaluate greenhouse gas efflux from rivers to the atmosphere

dynamic discontinuous stream networks hydrologically driven variations in active drainage density flowing channels and stream order despite decades of research on the ecological consequences of stream network expansion contraction and fragmentation surprisingly little is known about the hydrological mechanisms that shape these processes here we present field surveys of the active drainage networks of four california headwater streams 4 27 km2 spanning diverse topographic geologic and climatic settings we show that these stream networks dynamically expand contract disconnect and reconnect across all the sites we studied stream networks at all four sites contract and disconnect during seasonal flow recessions with their total active network length and thus their active drainage densities decreasing by factors of two to three across the range of flows captured in our field surveys the total flowing lengths of the active stream networks are approximate power law functions of unit discharge with scaling exponents averaging 0 27 0 04 range 0 18 0 40 the number of points where surface flow originates obey similar power law relationships as do the lengths and origination points of flowing networks that are continuously connected to the outlet with scaling exponents averaging 0 36 0 48 even stream order shifts seasonally by up to two strahler orders in our study catchments broadly similar stream length scaling has been observed in catchments spanning widely varying geologic topographic and climatic settings and spanning more than two orders of magnitude in size suggesting that network extension contraction is a general phenomenon that may have a general explanation points of emergence or disappearance of surface flow represent the balance between subsurface transmissivity in the hyporheic zone and the delivery of water from upstream thus the dynamics of stream network expansion and contraction and connection and disconnection may offer important clues to the spatial structure of the hyporheic zone and to patterns and processes of runoff generation copyright 2014 john wiley sons ltd

abnormal carbon and hydrogen isotopes of alkane gases from the qingshen gas field songliao basin china suggesting abiogenic alkanes abstract it is great debate that the alkane gases of abiogenic origin would constitute a major portion of the commercial accumulation of the qingshen gas field songliao basin china in this study abiogenic gases characterized by heavy 13c1 values reversal of the usual carbon isotopic trend of c1 c5 alkanes very narrow variation in 2hc1 values and low ch4 3he ratios associated with high r ra values 1 were identified the hydrocarbon gas in the qingshen gas field is a mixture of thermogenic alkanes derived from cretaceous mudstone type i kerogen or jurassic coal type iii kerogen and abiogenic alkanes mainly ch4 from mantle degassing a quantitative estimation of abiogenic alkanes contribution to the qingshen gas field is made based on a 13c1 vs 13c2 plot about 30 40 of alkane gases in the qingshen gas field along with its helium are estimated to be derived from the mantle via magmatic activity particularly the abiogenic formation of ch4 generated from the reduction of co2 by hydrothermal activity may contribute our study suggests that abiogenic alkane gases in certain geological settings could be more widespread than previously thought and may accumulate into economic reservoirs

a hydrogeomorphic river network model predicts where and why hyporheic exchange is important in large basins hyporheic exchange has been hypothesized to have basin scale consequences however predictions throughout river networks are limited by available geomorphic and hydrogeologic data and by models that can analyze and aggregate hyporheic exchange flows across large spatial scales we developed a parsimonious but physically based model of hyporheic flow for application in large river basins networks with exchange and subsurface storage nexss we applied nexss across a broad range of geomorphic diversity in river reaches and synthetic river networks nexss demonstrates that vertical exchange beneath submerged bed forms rather than lateral exchange through meanders dominates hyporheic fluxes and turnover rates along river corridors per kilometer low order streams have a biogeochemical potential at least 2 orders of magnitude larger than higher order streams however when biogeochemical potential is examined per average length of each stream order low and high order streams were often found to be comparable as a result the hyporheic zone s intrinsic potential for biogeochemical transformations is comparable across different stream orders but the greater river miles and larger total streambed area of lower order streams result in the highest cumulative impact from low order streams lateral exchange through meander banks may be important in some cases but generally only in large rivers

methane clumped isotopes in the songliao basin china new insights into abiotic vs biotic hydrocarbon formation abiotic hydrocarbon gas typically generated in serpentinized ultramafic rocks and crystalline shields has important implications for the deep biosphere petroleum systems the carbon cycle and astrobiology distinguishing abiotic gas produced by chemical reactions like sabatier synthesis from biotic gas produced from degradation of organic matter or microbial activity is sometimes challenging because their isotopic and molecular composition may overlap abiotic gas has been recognized in numerous locations on the earth although there are no confirmed instances where it is the dominant source of commercially valuable quantities in reservoir rocks the deep hydrocarbon reservoirs of the xujiaweizi depression in the songliao basin china have been considered to host significant amounts of abiotic methane here we report methane clumped isotope values 18 and the isotopic composition of c 1 c 3 alkanes co 2 and helium of five gas samples collected from those xujiaweizi deep reservoirs some geochemical features of these samples resemble previously suggested identifiers of abiotic gas 13 c enriched ch 4 decrease in 13 c 12 c ratio with increasing carbon number for the c1 c4 alkanes abundant apparently non biogenic co 2 and mantle derived helium however combining these constraints with new measurements of the clumped isotope composition of methane and careful consideration of the geological context suggests that the xujiaweizi depression gas is dominantly if not exclusively thermogenic and derived from over mature source rocks i e from catagenesis of buried organic matter at high temperatures methane formation temperatures suggested by clumped isotopes 167 213 c are lower than magmatic gas generation processes and consistent with the maturity of local source rocks also there are no geological conditions e g serpentinized ultramafic rocks that may lead to high production of h 2 and thus abiotic production of ch 4 via co 2 reduction we propose that the songliao gas is representative of an atypical type of thermogenic gas that can be mistaken for abiotic gas such gases may be encountered more frequently in future exploration of deep or over mature petroleum systems

mechanisms of shale gas storage implications for shale gas exploration in china this article reviews the mechanisms of shale gas storage and discusses the major risks or uncertainties for shale gas exploration in china at a given temperature and pressure the gas sorption capacities of organic rich shales are primarily controlled by the organic matter richness but may be significantly influenced by the type and maturity of the organic matter mineral composition especially clay content moisture content pore volume and structure resulting in different ratios of gas sorption capacity gsc to total organic carbon content for different shales in laboratory experiments the gsc of organic rich shales increases with increasing pressure and decreases with increasing temperature under geologic conditions assuming hydrostatic pressure gradient and constant thermal gradient the gsc increases initially with depth due to the predominating effect of pressure passes through a maximum and then decreases because of the influence of increasing temperature at greater depth this pattern of variation is quite similar to that observed for coals and is of great significance for understanding the changes in gsc of organic rich shales over geologic time as a function of burial history at an elevated temperature and pressure and with the presence of moisture the gas sorption capacities of organic rich shales are quite low as a result adsorption alone cannot protect sufficient gas for high maturity organic rich shales to be commercial gas reservoirs two models are proposed to predict the variation of gsc and total gas content over geologic time as a function of burial history high contents of free gas in organic rich shales can be preserved in relatively closed systems loss of free gas during postgeneration uplift and erosion may result in undersaturation the total gas contents lower than the sorption capacity and is the major risk for gas exploration in marine organic rich shales in china

geochemical characteristics and genesis of natural gas in the yan an gas field ordos basin china abstract the yan an gas field in the ordos basin china was discovered in 2014 and contains reserves of up to 100 billion m3 its occurrence in the basin contradicts the distribution model of gas in the north oil in the south upper paleozoic natural gas in the yan an area is dominated by methane with an average dryness coefficient c1 c1 4 of 99 5 13c1 30 8 to 27 5 with minor amounts of co2 3 8 n2 0 5 and ethane 13c2 37 2 to 30 5 and traces of higher hydrocarbons the gas is predominantly coal derived originating from carboniferous permian humic hydrocarbon source rocks and minor oil type gas from sapropelic source rocks the carbon isotope series includes reversals with 13c2

use of variable scale pressure test data to estimate the log hydraulic conductivity covariance and dispersivity of fractured granites near oracle arizona abstract application of modern stochastic theories to nonuniform geologic media requires among other things knowing the principal directions and correlation lengths of the log hydraulic conductivity covariance to infer this information by standard geostatistical methods directly from point measurements of hydraulic conductivity in three dimensional space is seldom possible due to a ubiquitous scarcity of data to show how this difficulty can be overcome we use an example of fractured granitic rocks near oracle arizona at this site hydraulic conductivities were measured on a small scale by packer tests and on a larger scale by cross hole tests the test results suggest that the measured hydraulic conductivities can be viewed as quantities defined over a continuum which are scalar on a local scale but exhibit large scale anisotropy due to spatial nonuniformity and the effect of fracture orientations based on this observation the two sets of hydraulic conductivity data are related theoretically and the resulting expression is used to estimate the anisotropic covariance function of log hydraulic conductivities at the oracle site we then employ these parameters to calculate a fickian dispersivity tensor for the oracle granite by relying on the recent theory of neuman et al 1987a our results highlight the need to extend available stochastic theories to the domain of strongly nonuniform media the properties of which fluctuate with large amplitudes

genetic characterization of natural gases natural gases can be characterized genetically using four properties c2 concentration carbon and hydrogen isotope variations in methane and carbon isotope variation in ethane three diagrams for genetic characterization of gases have been designed in which the carbon isotopic composition of methane is correlated with the other parameters in these diagrams compositional fields have been defined for primary gases biogenic thermogenic associated and thermogenic nonassociated and for gases which result from mixing of these gases these fields are strictly empirical and comprise compositional variations found in about 500 natural gases the isotopic and compositional variations in natural gases can be described in terms of 1 processes during formation of the gases such as bacterial fermentation or maturation of organic matter and 2 processes during secondary migration mixing of primary gases is an important and common process migration of gases predominantly affects the c2 concentration whereas the isotopic properties of gaseous hydrocarbons primarily remain unchanged allowing an assessment of the origin of migrated gases and properties of their source rocks the formation of gas from humic organic matter and coals is not yet clear from published data the diagrams use data from various basins and areas interstitial gases from the gulf of california are entirely of bacterial origin traces of thermogenic gases are formed only in the vicinity of dolerite sills gases in the south german molasse basin and in the vienna basin are of bacterial mixed and thermogenic origins data from the north italian po basin provide examples for genetic characterization of migrated gases

differential fluid migration behaviour and tectonic movement in lower silurian and lower cambrian shale gas systems in china using isotope geochemistry abstract isotope geochemistry has been introduced as a means to trace origin of the hydrocarbon and characterize highly productive shale gas systems recently to assess the impact of tectonic movement and the sealing of shale gas systems isotope geochemistry pressure coefficients and the distribution of bitumens are analysed many samples yield isotope geochemical data with typical carbon isotopic reversals 13 c 1 13 c 2 and hydrogen isotopic reversals 13 d c2h6 13 d ch4 in the lower silurian shale gas isotopically reversed gases are considered to originate in sealed self contained petroleum systems besides isotope reversals order degree of shale gas has positive correlation with gas production isotopically normal gases from the lower cambrian indicate that this formation was a continued relatively open petroleum system when oil and gas generated the pressure coefficients of the lower silurian shale gas reservoir range from 1 45 to 2 03 indicating that the reservoir is overpressurized whereas the lower cambrian shale gas reservoir possesses a normal pressure system overpressurization of the lower silurian shale gas reservoir also indicates that it is a well sealed system the distribution and isotope geochemistry of bitumens in the sinian dolomite and cambrian shale suggests that the source rock of the sinian hydrocarbon is the cambrian shale an unconformity induced from tectonic movement during the tongwan period is interpreted to be the fluid migration tunnel and the cause of the differential shale gas content and production finally the isotopic reversals associated with maturity pressure coefficients and tectonic evolution can both assess the preservation conditions of the reservoir and explain the differential fluid migration behaviour

stable isotope geochemistry of coal bed and shale gas and related production waters a review coal bed and shale gas can be of thermogenic microbial or of mixed origin with the distinction made primarily on the basis of the molecular and stable isotope compositions of the gases and production waters methane ethane carbon dioxide and nitrogen are the main constituents of coal bed and shale gases with a general lack of c2 hydrocarbon species in gases produced from shallow levels and more mature coals and shales evidence for the presence of microbial gas include 13c ch4 values less than 50 covariation of the isotope compositions of gases and production water carbon and hydrogen isotope fractionations consistent with microbial processes and positive 13c values of dissolved inorganic carbon in production waters the co2 reduction pathway is distinguished from acetate methyl type fermentation by somewhat lower 13c ch4 and higher d ch4 but can also have overlapping values depending on the openness of the microbial system and the extent of substrate depletion crossplots of 13c ch4 versus 13c co2 and d ch4 versus 13c h2o may provide a better indication of the origin of the gases and the dominant metabolic pathway than the absolute carbon and hydrogen isotope compositions of methane in the majority of cases microbial coal bed and shale gases have carbon and hydrogen isotope fractionations close to those expected for co2 reduction primary thermogenic gases have 13c ch4 values greater than 50 and 13c values that systematically increase from c1 to c4 and define a relatively straight line when plotted against reciprocal carbon number although coals and disseminated organic matter in shales represent a continuum as hydrocarbon source rocks current data suggest a divergence between these two rock types at the high maturity end in deep basin shale gas reversals or rollovers in molecular and isotopic compositions are increasingly reported in what is effectively a closed shale system as opposed to the relative openness in coal measure environments detailed geochemical studies of coal bed and shale gas and related production waters are essential to determine not only gas origins but also the dominant methanogenic pathway in the case of microbial gases

permeability tensor for discontinuous rock masses rock masses which commonly contain a large number of discontinuities are treated as homogeneous anisotropic porous media to formulate the corresponding permeability tensor this has been successfully achieved by introducing a symmetric tensor crack tensor which depends only on the geometry of the related cracks aperture size and orientation the principal directions associated with the symmetric crack tensor are coaxial with those of the permeability tensor the first invariant of the crack tensor is proportional to the mean permeability while the deviatoric part is related to the anisotropic permeability these results are well supported by numerical experiments on the permeability of cracked media by long remer wilson and witherspoon an actual rock mass moderately jointed granite was studied to see whether the crack tensor can be determined in situ stereology based on geometrical statistics provides a sound basis for determining the crack tensor in situ the crack tensor is obtained by

development of a global 90m water body map using multi temporal landsat images abstract this paper describes the development of a global 3 arc second water body map g3wbm using an automated algorithm to process multi temporal landsat images from the global land survey gls database we used 33 890 scenes from 4 gls epochs in order to delineate a seamless water body map without cloud and ice snow gaps permanent water bodies were distinguished from temporal water covered areas by calculating the frequency of water body existence from overlapping multi temporal landsat scenes by analyzing the frequency of water body existence at 3 arc second resolution the g3wbm separates river channels and floodplains more clearly than previous studies this suggests that the use of multi temporal images is as important as analysis at a higher resolution for global water body mapping the global totals of delineated permanent water body area and temporal water covered area are 3 25 and 0 49 million km2 respectively which highlights the importance of river floodplain separation using multi temporal images the accuracy of the water body classification was validated in hokkaido japan and in the contiguous united states using an existing water body databases there was almost no commission error and about 70 of lakes 1 km2 shows relative water area error

distinguishing kerogen and oil cracked shale gas using h c isotopic fractionation of alkane gases abstract the formation mechanism of 23 shale gas samples from the fuling shale gas field in the upper ordovician wufeng o3w formation lower silurian longmaxi s1l formation marine shales was investigated based on the carbon and hydrogen isotopes of methane ethane and propane fuling shale gas is mainly composed of alkane gases and has a dryness coefficient c1 c1 3 of 0 992 0 993 the reversed carbon isotopic trend where 13c1 13c2 is a typical characteristic indicating mixing of kerogen cracked gas and crude oil cracked gas the empirical correlations between ln c1 c2 vs ln c2 c3 and ln c1 c2 vs 13c of alkane gases at different thermal maturity levels were used to distinguish kerogen cracked gas from crude oil cracked gas five stages of kerogen cracking and crude oil cracking were identified with a wide range of thermal maturities vitrinite reflectance ro 1 ro 13c2 4 ro of 1 8 2 5 residual kerogen cracking proceeded to generate ch4 and light oil cracking generated heavier gaseous hydrocarbons with a completely reversed carbon isotopic trend of alkane gases 13c1 13c2 13c3 5 ro 2 5 further cracking of heavier gaseous hydrocarbons generated ch4

a subgrid channel model for simulating river hydraulics and floodplain inundation over large and data sparse areas 1 this paper presents a new computationally efficient hydraulic model for simulating the spatially distributed dynamics of water surface elevation wave speed and inundation extent over large data sparse domains the numerical scheme is based on an extension of the hydraulic model lisflood fp to include a subgrid scale representation of channelized flows which allows river channels with any width below that of the grid resolution to be simulated the scheme is shown to be numerically stable and scalable before being applied to an 800 km reach of the river niger in mali the niger application focused on the performance of four different model structures a model without channels two dimensional 2 d model a model without a floodplain one dimensional 1 d model a model of the main channels and floodplain 1 d 2 d model and the subgrid approach developed here inclusion of both the channel network and the floodplain was shown to be essential meaning that large scale models of this region including routing models for land surface schemes will require a floodplain component including subgrid scale channels on the floodplain changed inundation dynamics over the delta significantly and increased simulation accuracy in terms of water level wave propagation speed and inundation extent furthermore only the subgrid model showed a consistent parameterization when calibrated against either gauge or icesat water level data suggesting that connectivity provided by small channels is a strong control on the hydraulics of the floodplain or at the very least that low resolution gridded hydraulic models require additional connectivity to represent the delta flow dynamics

noble gases solubility models of hydrocarbon charge mechanism in the sleipner vest gas field abstract noble gases are chemically inert and variably soluble in crustal fluids they are primarily introduced into hydrocarbon reservoirs through exchange with formation waters and can be used to assess migration pathways and mechanisms as well as reservoir storage conditions of particular interest is the role groundwater plays in hydrocarbon transport which is reflected in hydrocarbon water volume ratios here we present compositional stable isotope and noble gas isotope and abundance data from the sleipner vest field in the norwegian north sea sleipner vest gases are generated from primary cracking of kerogen and the thermal cracking of oil gas was emplaced into the sleipner vest from the south and subsequently migrated to the east filling and spilling into the sleipner ost fields gases principally consist of hydrocarbons 83 93 co2 5 4 15 3 and n2 0 6 0 9 as well as trace concentrations of noble gases helium isotopes 3he 4he are predominantly radiogenic and range from 0 065 to 0 116 ra reported relative to air ra 1 4 10 6 clarke et al 1976 sano et al 1988 showing predominantly 98 crustal contributions consistent with ne 20ne 22ne from 9 70 to 9 91 21ne 22ne from 0 0290 to 0 0344 and ar isotopes 40ar 36ar from 315 to 489 air derived noble gas isotopes 20ne 36ar 84kr 132xe are introduced into the hydrocarbon system by direct exchange with air saturated water asw the distribution of air derived noble gas species are controlled by phase partitioning processes in that they preferentially partition into the gas i e methane phase due to their low solubilities in fluids therefore the extent of exchange between hydrocarbon phases and formation waters that have previously equilibrated with the atmosphere can be determined by investigating air derived noble gas species we utilize both elemental ratios to address process i e open vs closed system and concentrations to quantify the extent of hydrocarbon water exchange i e volumetric gas water ratios these data are discussed within the framework of several conceptual models i total gas stripping model which assumes all noble gases have been stripped from the water phase thus defining the minimum volume of water to have interacted with the hydrocarbon phase ii equilibrium model which assumes equilibration between groundwater and hydrocarbon phase at reservoir p t and salinity and iii open and closed system gas stripping models using concentrations and elemental ratios by applying these models to ne ar data from sleipner we estimate volumetric gas water ratios v g v w between 0 02 and 0 07 which are lower than standard geologic gas water estimates of 0 24 estimated by combining gas in place estimates with groundwater porosity estimates sleipner vest data can be best approximated by an open system model which predicts more than an order of magnitude more groundwater interaction during migration than geologic estimates indicating a dynamic aquifer system and or a hydrous migration pathway in an open system the extent of gas loss can be estimated to be between 8 and 10 reservoir volumes which have passed through the system and been lost i e filled and spilled

comparison of rev size and tensor characteristics for the electrical and hydraulic conductivities in fractured rock the representative elementary volume rev is a critically important concept in fractured rock investigations as it tells us at what scale the fractured domain can be represented by an anisotropic tensor as opposed to requiring the details of each individual fracture for modelling purposes whereas the rev size and corresponding tensor characteristics for the hydraulic conductivity k in fractured rock have been the subject of numerous previous investigations no studies to date have focused on the electrical conductivity this is despite the fact that geoelectrical measurements are arguably the most popular means of geophysically investigating fractured rock typically via azimuthal resistivity surveying where the observed electrical anisotropy is commonly used to infer hydraulic characteristics in this paper we attempt to fill this void and present a systematic numerical study of the impacts of changes in fracture network properties on the rev size and equivalent tensor characteristics for both the electrical and hydraulic conductivities we employ a combined statistical and numerical approach where the size of the rev is estimated from the conductivity variability observed across multiple stochastic fracture network realizations for various domain sizes two important differences between fluid and electric current flow in fractured media are found to lead to significant differences in the rev size and tensor characteristics for and k these are the greater importance of the matrix in the electrical case and the single power instead of cubic dependence of electric current flow upon aperture specifically the rev for the electrical conductivity will always be smaller than that for the hydraulic conductivity and the corresponding equivalent tensor will exhibit less anisotropy often with notably different principal orientations these findings are of key importance for the eventual interpretation of geoelectrical measurements in fractured rock where we conclude that extreme caution must be taken when attempting to make the link to hydraulic properties

distribution composition and origin of coalbed gases in excavation fields from the preloge and pesje mining areas velenje basin slovenia abstract coal gas outbursts especially co 2 present a high risk in mining of lignite in the velenje coal mine located in the velenje basin in northern slovenia a programme of monitoring geochemical parameters was set up to help understand the behaviour of the coalbed gas distribution in advance of the working face using mass spectrometric methods to study its molecular and isotopic compositions and origin coalbed gas samples from four different excavation fields g2 c and k 130 a from the north and south preloge mining area and k 5 a and k 50 c from the pesje mining area which were operational between the years 2010 and 2011 were investigated the major gas components are co 2 and methane temporal changes in the chemical and isotopic composition of free seam gases were observed within boreholes as a function of the advancement of the working face the study also revealed that at a distance of around 120 m from the working face the influence of coal exploitation by the velenje longwall mining method causes coalbed gas to migrate at a distance of 70 m the lignite structure is crushed causing desorption of fixed co 2 from the coal differences in coalbed gas composition at the longwall panels which underlie the unmined area or under previously mined areas were found a high cdmi co 2 co 2 ch 4 100 index with values up to 95 6 was typical for areas of pre mined excavation fields south preloge k 130 a and pesje area k 5 a while in excavation fields with no previous mining activity north preloge g2 c and pesje area k 50 c up to 61 9 vol of ch 4 was detected the concentration measurements and isotopic studies revealed endogenic co 2 including co 2 originating from dissolution of carbonates with 13 c co2 values ranging from 7 0 to 5 5 microbial methane and co 2 with values ranging from 70 4 to 50 and from 11 0 to 7 0 respectively higher 13 c ch4 values ranging from 50 to 19 8 could be attributed to so called secondary processes influencing the 13 c ch4 value such as migration due to lignite excavation escape of isotopically lighter methane in excavation fields g2 c and k 50 c with no premining activity higher 13 c ch4 values could also be explained by migration of methane from deeper strata the 13 c ch4 value also depended on the depth of the excavation field at shallower levels of the excavation field k 5 a a lower 13 c ch4 value was traced indicating microbial gas while at deeper levels higher 13 c ch4 values were found

the effects of spatial resolution and dimensionality on modeling regional scale hydraulics in a multichannel river as modeling capabilities at regional and global scales improve questions remain regarding the appropriate process representation required to accurately simulate multichannel river hydraulics this study uses the hydrodynamic model lisflood fp to simulate patterns of water surface elevation wse depth and inundation extent across a 90 km anabranching reach of the tanana river alaska to provide boundary conditions we collected field observations of bathymetry and wse during a 2 week field campaign in summer 2013 for the first time at this scale we test a simple raster based model s capabilities to simulate 2 d in channel patterns of wse and inundation extent additionally we compare finer resolution 25 m 2 d models to four other models of lower dimensionality and coarser resolution 100 500 m to determine the effects of simplifying process representation results indicate that simple raster based models can accurately simulate 2 d in channel hydraulics in the tanana also the fine resolution 2 d models produce lower errors in spatiotemporal outputs of wse and inundation extent compared to coarse resolution 1 d models 22 6 cm versus 56 4 cm rmse for wse and 90 versus 41 critical success index values for simulating inundation extent incorporating the anabranching channel network using subgrid representations for smaller channels is important for simulating accurate hydraulics and lowers rmse in spatially distributed wse by at least 16 as a result better representation of the converging and diverging multichannel network by using subgrid solvers or downscaling techniques in multichannel rivers is needed to improve errors in regional to global scale models

experimental study on the gas generation processes of lacustrine and marine shales in north china source implications for shale gas abstract using a high pressure semi closed thermal simulation system two organic rich lacustrine and marine immature shales from north china were investigated to probe the dynamic processes and potential for the gas generation throughout the oil gas window the results identified at least two processes during gas generation as revealed by changes of the gas dry coefficient c1 c1 5 and carbon isotopic composition of methane 13cmethane the first process is associated with kerogen thermal degradation and occurs during the main phase of oil generation showing an increasing trend of the dry coefficient and 13cmethane the second process begins during the late phase of oil generation accompanied by increasing yields of wet gas components and 13c depleted methane due to the lack of aliphatic carbon in kerogen in the highly to over mature stage as demonstrated by ftir analyses the second process is mainly related to the cracking of kerogen generated bitumen which is retained in the shale the hydrogen content a key parameter for petroleum generation is then used to quantitatively evaluate the gas generation potential from kerogen thermal degradation and retained bitumen cracking mass balance calculations show that kerogen generated bitumen that is retained in lacustrine and marine shales is estimated to contribute 30 of the total gas yields at the stage of 1 5 2 0 ro this result is consistent with the theoretical calculations from xia et al 2013 and has important implications for the shale gas sources and further the shale gas resource assessments before exploration in shale gas petroleum systems

isotopic reversals with respect to maturity trends due to mixing of primary and secondary products in source rocks abstract carbon isotopic composition 13 c reversals with respect to maturity trends have been reported for ethane and propane in barnett shale gas in the fort worth basin u s a this trend also exists in some conventional gas reservoirs such as in the ordos basin china and appalachian basin u s a fractionation during mass transport is unlikely to be a significant mechanism because its effect is minor under geological conditions it would have caused more obvious reversal for methane than for ethane and propane and mass transport can not account for the occurrence of the trend both inside and outside source rocks this paper demonstrates that the reversal may result from mixing of indigenous primary gas generated directly from kerogen and secondary gas generated from oil and condensate within source rocks and presents deconvolution results using end members derived from a kinetic isotope fractionation model the results including the wetness and mixing ratio of primary and secondary gases are consistent with geological conditions condensates may be the major precursor of the secondary gas in shale when the reversal occurs a complete trend of 13 c variations in methane and ethane with maturity is proposed that is based on the indigenous mixing mechanism

spatial and temporal patterns in arctic river ice breakup revealed by automated ice detection from modis imagery abstract the annual spring breakup of river ice has important consequences for northern ecosystems and significant economic implications for arctic industry and transportation river ice breakup research is restricted by the sparse distribution of hydrological stations in the arctic where limited available data suggests a trend towards earlier ice breakup the specific climatic mechanisms driving this trend however are complex and can vary both regionally and within river systems consequently understanding the response of river ice processes to a warming arctic requires simultaneous examination of spatial and temporal patterns in breakup timing in this paper we describe an automated algorithm for river ice breakup detection using modis satellite imagery that enables identification of spatial and temporal breakup patterns at large scales we examine breakup timing on the mackenzie lena ob and yenisey rivers for the period 2000 2014 by dividing the rivers into 10 km segments and classifying each river pixel in each segment as snow ice mixed ice water or open water based on modis reflectance we determine breakup dates with a mean uncertainty of 1 3 days all statistically significant temporal trends are negative indicating an overall shift towards earlier breakup considerable variability in the statistical significance and magnitude of trends along each river suggests that different climatic and physiographic drivers are impacting spatial patterns in breakup trends detected on the lower mackenzie corroborate recent studies indicating weakening ice resistance and earlier breakup timing near the mackenzie delta in siberia the increased magnitude of trends upstream and strong correlation between breakup initiation and whole river breakup patterns suggest that earlier onset of upstream discharge may play the dominant role in determining breakup timing exploratory analysis demonstrates that modis imagery may also be used to differentiate thermal and mechanical breakup events

bulk and position specific isotope geochemistry of natural gases from the late cretaceous eagle ford shale south texas abstract a dataset of bulk and position specific isotope compositions of shale gases from the late cretaceous eagle ford shale south texas is reported the chemical and bulk isotopic compositions of the seven samples in this study and those available from the literature show that across the play produced natural gas from the eagle ford shale preserves a wide range of gas compositions wetness 5 to 90 and 13c values of c1 c3 the depth profiles of the isotopic compositions suggest that the western region of the eagle ford shale deposit had experienced as much as 700 800 m of uplift erosion or gas migration the timing of and lost gas fractions by gas expulsion events very likely affected their gas compositions and bulk isotope compositions some deep 3000 3500 m matured ro 1 5 gases with heavy 13c c1 c3 values indicate significant loss 50 of the early stage gases for the position specific isotope deviations of propane the c2 1 values of the five samples show small decrease with well depths while the h2 1 values have a general increasing trend although some samples fall very close to the equilibrium model trajectories with reasonable calculated temperatures 138 148 c the position specific isotope compositions of propane from the eagle ford shale gases are likely results of thermal cracking of various organic molecules within the source rocks which have different activation energy for cracking and non statistical distributions of c h isotope within them

thermal maturation of gas shale systems shale gas systems serve as sources reservoirs and seals for unconventional natural gas accumulations these reservoirs bring numerous challenges to geologists and petroleum engineers in reservoir characterization most notably because of their heterogeneous character due to depositional and diagenetic processes but also because of their constituent rocks fine grained nature and small pore size much smaller than in conventional sandstone and carbonate reservoirs significant advances have recently been achieved in unraveling the gaseous hydrocarbon generation and retention processes that occur within these complex systems in addition cutting edge characterization technologies have allowed precise documentation of the spatial variability in chemistry and structure of thermally mature organic rich shales at the submicrometer scale revealing the presence of geochemical heterogeneities within overmature gas shale samples and notably the presence of nanoporous pyrobitumen such research advances will un

stable isotope geochemistry of the nitrogen rich gas from lower cambrian shale in the yangtze gorges area south china abstract the organic rich marine shales from the lower cambrian niutitang formation in the yangtze gorges area are characterized by their high toc values 0 54 5 13 types i and ii organic matter and high ro values 2 4 2 6 geochemical parameters of 19 gas samples from the lower cambrian shale formation from well zd 1 were analyzed in this study the gases are dominated by methane with small amounts of ethane and no propane or butane the 13 c ch 4 values range from 31 7 to 27 9 the 13 c c 2 h 6 values range from 35 2 to 33 4 and the 2 h ch 4 values range from 214 to 187 furthermore carbon isotopic compositions of the alkane gases from the lower cambrian shale are characterized by 13 c 1 13 c 2 these results indicate that the gases are of thermogenic origin and are oil derived moreover methane with heavy carbon isotopic and light hydrogen isotopic values may be produced when water reacts with inorganic carbon the isotopic reversal of alkane gases was probably due to destructive redox reactions at maximum burial resulting in rayleigh type fractionation and or mixing by gases from the same source but at a different maturity nitrogen occurs in the analyzed gases at concentrations from 8 15 to 96 52 and the 15 n n 2 values vary from 3 2 to 7 4 the 15 n n 2 values and high illite content suggest that nitrogen was mainly generated during thermal transformation of organic matter and or from nh 4 rich illites of the clayey facies of the lower cambrian shale carbon dioxide concentrations vary from 1 13 to 4 96 and the 13 c co 2 values range from 8 9 to 13 6 this suggests that carbon dioxide was mainly generated during thermogenic processes of transformation of organic matter moreover the major reason for the change in nitrogen and methane contents in the studied well zd 1 is probably due to the development of micro cracks in core samples with high contents of nitrogen a high nitrogen content may be caused by the strong adsorption capacity of nitrogen which leads to the retention of nitrogen and the diffusion of methane in shale

isotopic reversal rollover in shale gases produced from the mississippian barnett and fayetteville formations abstract ethane propane and carbon dioxide show reversed carbon isotopic maturity trends in natural gas produced from the barnett and fayetteville shales at thermal maturities greater than 1 5 vre at this high level of thermal maturity the iso butane to n butane ratio also reverses suggesting wet gas cracking has occurred generating more gas molecules in the same volume resulting in overpressure and increased stabilized production rates in the barnett hydrothermal fluids from the nearby ouachita thrust front apparently enhanced the maturity of the fayetteville and barnett shales water hydrocarbon reactions at these high maturities may account for the isotopic reversals

oil and gas geochemistry and petroleum systems of the fort worth basin detailed biomarker and light hydrocarbon geochemistry confirm that the marine mississippian barnett shale is the primary source rock for petroleum in the fort worth basin north central texas although contributions from other sources are possible biomarker data indicate that the main oil generating barnett shale facies is marine and was deposited under dysoxic strong upwelling normal salinity conditions the analysis of two outcrop samples and cuttings from seven wells indicates variability in the barnett shale organic facies and a possibility of other oil subfamilies being present light hydrocarbon analyses reveal significant terrigenous sourced condensate input to some reservoirs resulting in terrigenous and mixed marine terrigenous light hydrocarbon signatures for many oils the light hydrocarbon data suggest a secondary condensate generating source facies containing terrigenous or mixed terrigenous marine organic matter this indication of a secondary source rock that is not revealed by biomarker analysis emphasizes the importance of integrating biomarker and light hydrocarbon data to define petroleum source rocks gases in the fort worth basin are thermogenic in origin and appear to be cogenerated with oil from the barnett shale although some gas may also originate by oil cracking isotope data indicate minor contribution of biogenic gas except for reservoirs in the pennsylvanian bend group which contain gases spanning the complete range of observed maturities the gases appear to be stratigraphically segregated younger reservoirs contain less mature gas and older reservoirs contain more mature gas we cannot rule out the possibility that other source units within the fort worth basin such as the smithwick shale are locally important petroleum sources

estimation of multiple inflows and effective channel by assimilation of multi satellite hydraulic signatures the ungauged anabranching negro river abstract with the upcoming swot satellite mission which should provide spatially dense river surface elevation width and slope observations globally comes the opportunity to assimilate such data into hydrodynamic models from the reach scale to the hydrographic network scale based on the hivdi hierarchical variational discharge inversion modeling strategy larnier et al 2020 this study tackles the forward and inverse modeling capabilities of distributed channel parameters and multiple inflows in the 1d saint venant model from multisatellite observations of river surface it is shown on synthetic cases that the estimation of both inflows and distributed channel parameters bathymetry friction is achievable with a minimum spatial observability between inflows as long as their hydraulic signature is sampled next a real case is studied 871 km of the negro river amazon basin including complex multichannel reaches 21 tributaries and backwater controls from major confluences an effective modeling approach is proposed using i ws elevations from envisat data and dense in situ gps flow lines moreira 2016 ii average river top widths from optical imagery pekel et al 2016 iii upstream and lateral flows from the mgb large scale hydrological model paiva et al 2013a the calibrated effective hydraulic model closely fits satellite altimetry observations and presents real like spatial variabilities flood wave propagation and water surface observation frequential features are analyzed with identifiability maps following brisset et al 2018 synthetic swot observations are generated from the simulated flowlines and allow to infer model parameters 436 effective bathymetry points 17 friction patches and 22 upstream and lateral hydrographs given hydraulically coherent prior parameter values inferences of channel parameters carried out on this fine hydraulic model applied at a large scale give satisfying results using noisy swot like data at reach scale inferences of spatially distributed temporal parameters lateral inflows give satisfying results as well with even relatively small scale hydrograph variations being inferred accurately on this long reach this study brings insights in i the hydraulic visibility of the signatures of multiple inflow hydrographs at a large scale with swot ii the simultaneous identifiability of spatially distributed channel parameters and inflows by assimilation of satellite altimetry data iii the need for prior information iv the need to further tailor and scale network hydrodynamic models and assimilation methods to improve the fusion of multisource information and potential information feedback to hydrological modules in integrated chains