Gas Composition Data Research Articles

PH OF BONE MARROW

The bone marrow is a “niche” for stem cells; determining the bone marrow pH value is of great importance. It is very difficult, almost impossible, to carry out the intravital determination of pH. In surgical practice, there are situations when doctors have no way to save the patient's lower limb because of the threat to life. In such cases, it is possible to extract the bone marrow from the bone marrow cavity of the amputated femur and examine it. The purpose of this research was to study the acid-base balance peculiarities of the marrow of long bones and carry out a comparative analysis of the obtained data and the indicators of flat bones. The study included 40 test samples of bone marrow. Lower limb amputations were performed because of foot gangrene. Bone marrow was extracted from the femur. The marrow of flat bones was obtained by a sternal puncture. In the pH test of the sternal puncture, the data varied within the range of the blood pH, i.e., between 7.35-7.45 and 7.8. The pH and gas composition data of the sternal puncture were identical to the blood indicators. The data of bone marrow obtained from the long bone was completely different. The acid-base balance strictly ranged from 6.7 to 6.9.

Reaction path modelling illustrating the fluid history of a natural CO2-H2S reservoir

Despite the increasing interest in geologic co-sequestration of CO2 and H2S, the long-term consequences of the chemical interactions involved in this process remain largely unknown on a reservoir scale. A Mississippian aged CO2-H2S reservoir in LaBarge Field, Wyoming, USA is an ideal study site to investigate mineral and fluid reactions related to gaseous H2S and CO2. We conducted two reaction path models based on mineralogical, fluid, gas, and stable isotope compositional data to discern the role of CO2 influx upon the generation of H2S through thermochemical sulphate reduction (TSR). We discriminate between two models-one in which TSR is triggered by temperature at a given burial depth and one where TSR is triggered by ingress of CO2. The reaction path model based upon burial-controlled TSR and later CO2 influx is consistent with mineralogical observations and stable isotope measurements from drill cores. The models show that CO2 influx leads to calcite precipitation which is only limited by the calcium concentration in the fluid. This modelling approach is useful in constraining the timing of fluid flux in the reservoir and gives further insight into the mineralogical consequences of the gas, water, and rock interactions occurring in the reservoir. In terms of geologic co-sequestration this implies that the addition of CO2 into a reducing carbonate system can result in calcite precipitation, instead of anhydrite as previously thought. Furthermore, it is only limited by the availability of Ca2+ and will therefore not diminish the amount of H2S in the system.

Quantifying the helium and hydrocarbon accumulation processes using noble gases in the North Qaidam Basin, China

Limited reserves and insecure resource supply have led to global shortage crises in helium, a vital gas for cryogenic engineering and other countless industrial manufacturing processes. Despite the attention drawn by global supply disruptions, the helium accumulation mechanism in natural gas fields remains poorly understood. Noble gases are excellent tracers for studying migration and accumulation processes of fluids in the subsurface and can be used to investigate the influence of subsurface fluids on helium accumulation. We present noble gas isotope and abundance data as well as major gas compositional data from 10 producing wells in three gas fields in the North Qaidam Basin, China. Helium is more concentrated in the Mabei and Dongping gas fields (2.06–48.4 × 10−4 cm3 STP/cm3) than in the Niudong gas field (1.15–1.42 × 10−4 cm3 STP/cm3). The helium is mainly radiogenic, with 3He/4He ratios of 0.01–0.05 Ra, where Ra is the atmospheric value of 3He/4He, and lacks significant contribution from the mantle (0.03–0.67%). The noble gases derived from air-saturated water (20Ne, 36Ar, 84Kr and 130Xe) can be explained by an oil-modified groundwater-exsolution model with excess heavy noble gases. The calculated Voil/Vwater and Vgas/Vwater ratios indicate that the Mabei region is the most oil-rich area and the Dongping region has the driest natural gas, which is consistent with the geological context. These ratios further support the fractionation models. The strong linear relationship between 4He and 20Ne (R2 = 0.98) suggested that 4He was dissolved into groundwater before migrating into the oil or gas phase. The initial 4He concentrations in groundwater can accumulate within 0.31–2.78 Myr assuming a 4He flux from the entire crustal section. According to the fractionation model, helium in groundwater partitions into the gas phase when contacting hydrocarbons. The different volume ratios among oil, gas and water during the equilibration process cause much greater variability in the helium concentrations in the gas phase (e.g., 6.08 × 10−4 to 2.01 × 10−3 cm3 STP/cm3 in Mabei) than those in the groundwater phase (e.g. 9.18 × 10−3 to 1.39 × 10−2 cm3 4He STP/cm3 H2O in Mabei). Hydrocarbons play a critical role in helium accumulation and dilution. Helium-rich natural gas fields are characterized by old groundwater systems and moderate hydrocarbon abundance. This study has succeeded in quantitatively assessing the helium accumulation process in natural gas fields in the North Qaidam Basin and revealed that both groundwater and hydrocarbon phases control the helium accumulation in the subsurface environment. This outcome has broad implications for the prediction of hydrocarbon and helium as resources.

Implementation of LabVIEW as a Virtual Instrument in a Cost‐Effective Isolated Lung Setup

IntroductionIsolated lung experiments allow for ex vivo characterization of lung function and prove to be a valuable model for various fields such as cancer, lung transplantation, and ischemia/reperfusion injury. Unlike other models that require damaging the lung, the isolated lung allows for collection of physiological changes including airway pressure, pulmonary artery and vein pressure, airway flow, and, in our model, ventilated gas concentrations. We describe the use of LabVIEW combined with the free statistical software R for highly flexible, effective, and automated data collection in an isolated lung system.MethodsPressure transducers connected to bioamplifiers allow for collection of dynamic pulmonary artery and vein pressures, while airway pressure and flow are collected from the ventilator with the former used to visualize positive end expiratory pressure. Signals from these devices are connected to an analog‐digital converter from National InstrumentsTM that collects data into LabVIEW software, which is then automatically collected and displayed at 200Hz. Use of a roller pump with analog input/output allows for fully automated control of the perfusion speed. Output from a gas mixer for use in ventilated gas studies is collected and used to generate gas composition data. Additional experimental data that do not have signal output capability can be recorded manually in LabVIEW.ResultsLabVIEW is a reliable alternative to other commercially available data acquisition systems. The creation of a virtual instrument requires significant programming knowledge but allows for completely customizable data collection in a modular isolated lung system. Data become available in an Excel‐compatible file which can then be imported and analysed in R as another affordable alternative to commercial programs.ConclusionWe describe the design and implementation of a LabVIEW virtual instrument as an adjustable alternative to conventional data acquisition systems.Support or Funding InformationThis work was supported, in part, by institutional funds, NIH grant (5R01 HL123227), and a Merit Review Award (I01 BX003482) from the U.S. Department of Veterans Affairs Biomedical Laboratory R&D Service.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Dynamics of Outgassing and Plume Transport Revealed by Proximal Unmanned Aerial System (UAS) Measurements at Volcán Villarrica, Chile

AbstractVolcanic gas emissions are intimately linked to the dynamics of magma ascent and outgassing and, on geological time scales, constitute an important source of volatiles to the Earth's atmosphere. Measurements of gas composition and flux are therefore critical to both volcano monitoring and to determining the contribution of volcanoes to global geochemical cycles. However, significant gaps remain in our global inventories of volcanic emissions, (particularly for CO2, which requires proximal sampling of a concentrated plume) for those volcanoes where the near‐vent region is hazardous or inaccessible. Unmanned Aerial Systems (UAS) provide a robust and effective solution to proximal sampling of dense volcanic plumes in extreme volcanic environments. Here we present gas compositional data acquired using a gas sensor payload aboard a UAS flown at Volcán Villarrica, Chile. We compare UAS‐derived gas time series to simultaneous crater rim multi‐GAS data and UV camera imagery to investigate early plume evolution. SO2 concentrations measured in the young proximal plume exhibit periodic variations that are well correlated with the concentrations of other species. By combining molar gas ratios (CO2/SO2 = 1.48–1.68, H2O/SO2 = 67–75, and H2O/CO2 = 45–51) with the SO2 flux (142 ± 17 t/day) from UV camera images, we derive CO2 and H2O fluxes of ~150 t/day and ~2,850 t/day, respectively. We observe good agreement between time‐averaged molar gas ratios obtained from simultaneous UAS‐ and ground‐based multi‐GAS acquisitions. However, the UAS measurements made in the young, less diluted plume reveal additional short‐term periodic structure that reflects active degassing through discrete, audible gas exhalations.

Biomethane production monitoring and data analysis based on the practical operation experiences of an innovative power-to-gas benchscale prototype

Power-to-gas (P2G) is referred to technologies that convert carbon dioxide into methane. Both bio- and chemical catalysts may be used for conversion purposes. One of the most disruptive biotechnologies was developed by the University of Chicago (IL) (publication number: EP2661511B1), using a robust, highly selective, patented strain of Archaea. Electrochaea GmbH has developed an innovative bench-scale P2G prototype unit, which uses this highly efficient Archaea strain, specialized components and specifically developed control strategies. The structure and the components of the prototype are equivalent with the functional parts of the currently largest commercial scale biomethanation BioCat plant located in Avedøre, Denmark (www.biocat-project.com). Power-to-Gas Hungary Kft. has committed to further develop this innovative technology. The first steps of this development have been taken by operating the benchscale unit and analyzing the data of the operating periods.
 The prototype is operated based on weekly campaigns. During continuous operation, H2O is generated as a by-product of methane. Therefore, approximately 200 ml of biocatalyst is discharged each day and concentrated media containing macro and micronutrients are injected into the reactor to maintain media composition. The laboratory staff records all gas composition data each morning. The gas composition is measured every 12 minutes by an Awite AwiFlex Cool+ gas analyzer. Within this article, we analyze the collected datasets containing more than 12 000 records and present the first practical experiences of the operations of the innovative power-to-gas bench-scale prototype.
 The analysis of the collected gas composition data of the product gas already provides important data for modelling the commercial-scaled processes. The average value of VVD was about 40 l/l/d in the period under review. Further increase of the methane content can be achieved by introduction of higher mixing energy and by increasing pressure levels in the bioreactor (as demonstrated in the BioCat plant – data not shown here) – both of which are strategies envisioned for the commercial plant. In routine activities (turn on, shut down, continuous operation) we could verify the high robustness of the biocatalyst and the base connection between the registered datasets and performed test results.

Methane and ethane emission scenarios for potential shale gas production in Europe

Abstract. A main concern surrounding (shale) gas production and exploitation is the leakage of methane, a potent greenhouse gas. High leakage rates have been observed outside of Europe but the representativeness of these observations for Europe is unknown. To facilitate the monitoring of methane leakage from a future shale gas industry in Europe we developed potential production scenarios for ten major shale gas plays and identified a suitable tracer in (shale) gas to distinguish oil and gas related emissions from other methane sources. To distinguish gas leakage from other methane sources we propose ethane, a known tracer for leakage from oil and gas production but absent in emissions from other important methane sources in Europe. Ethane contents for the ten plays are estimated from a European gas composition database and shale gas composition and reservoir data from the US, resulting in three different classes of ethane to methane ratios in the raw gas (0.015, 0.04 and 0.1). The ethane content classes have a relation with the average thermal maturity, a basic shale gas reservoir characteristic, which is known for all ten European shale gas plays. By assuming different production scenarios in addition to a range of possible gas leakage rates, we estimate potential ethane tracer release by shale gas play. Ethane emissions are estimated by play following a low, medium or high gas production scenario in combination with leakage rates ranging from 0.2 %–10 % based on observed leakage rates in the US.

Optical refractivity in Ar–CO2, plasmas at λ=632.8 nm

Abstract The refractive index of a high-temperature gas is influenced simultaneously by composition and therefore by temperature. Gas composition data are needed to evaluate the gas temperature. This paper deals with the calculation of equilibrium composition by Gibbs free energy minimization method in Ar–CO 2 mixtures at atmospheric pressure in the temperature range between 300 and 4000 K. Next, Ar–CO 2 refractivities are computed versus plasma temperature using the relationship between refractivity and temperature obtained by using a state equation and the Gladstone–Dale relation. Finally, a fitting formula for the refractivity as a function of temperature is obtained for each mixture Ar–CO 2 .

Gas quantity and composition from the hydrolysis of salt cake from secondary aluminum processing.

A systematic approach to understanding the hydrolysis of salt cake from secondary aluminum production in municipal solid waste landfill environment was conducted. Thirty-nine (39) samples from 10 Aluminum recycling facilities throughout the USA were collected. A laboratory procedure to assess the gas productivity of SC from SAP under anaerobic conditions at 50 °C to simulate a landfill environment was developed. Gas quantity and composition data indicate that on average 1400 µmol g-1 (35 mL g-1) of gas resulted from the hydrolysis of SC. Hydrogen was the dominant gas generated (79% by volume) followed by methane with an average of 190 µmol g-1 (21% by volume). N2O was detected at a much lower concentration (1.2 ppmv). The total ammonia released was 680 µmol g-1, and because of the closed system nature of the experimental setup, the vast majority of ammonia was present in the liquid phase (570 mg L-1). In general, the productivity of both hydrogen and total ammonia (the sum of gas and liquid forms ammonia) was a fraction of that expected by stoichiometry indicating an incomplete hydrolysis and a potential for re-hydrolysis when conditions are more favorable. The result provides substantial evidence that SC can be hydrolyzed to generate a gas with relative long-lasting implications for municipal solid waste landfill operations.

Dehydration Simulation of Natural Gas by using Tri Ethylene Glycol

Water content in natural gas poses threat to process facilities such as column distillation. Natural gas from reservoirs usually contains water vapor, the presence of water vapor in gas processing causes bad impact to process facilities. Dry Gas composition data was taken from Salamander Energy. Optimization of natural gas dehydration using Tri Ethylene Glycol was carried out using Aspen HYSYS V8.6 with Peng-Robinson fluid package. The natural gas dehydrating plant was designed with operating conditions of 394 bar and 460C and 10 MMSCFD and 6.8 MMSCFD gas flow rate were inputted. Results obtained from HYSYS simulation shows. Three different TEG flowrates were used for this simulation. Results obtained from simulation that . For the purpose of running the plant economically, the minimum flow rate of TEG which will reduce the water content to within the limit of pipeline specification, is very important and the result obtained showed that a minimum of 3 m3/h of TEG is required to reduce the water content of a gas stream of 10MMSCFD to 6.8lb/MMSCFD, which is within the limit of 6-7lb/MMSCFD, this value when compare to gas plant which uses 15m3/h for the gas stream of 10MMSCFD to achieve the same water content specification is far lower. Values below this flow rate (3.5m3/h) may not reduce the water content to the specified limit.

Quantifying alkane emissions in the Eagle Ford Shale using boundary layer enhancement

Abstract. The Eagle Ford Shale in southern Texas is home to a booming unconventional oil and gas industry, the climate and air quality impacts of which remain poorly quantified due to uncertain emission estimates. We used the atmospheric enhancement of alkanes from Texas Commission on Environmental Quality volatile organic compound monitors across the shale, in combination with back trajectory and dispersion modeling, to quantify C2–C4 alkane emissions for a region in southern Texas, including the core of the Eagle Ford, for a set of 68 days from July 2013 to December 2015. Emissions were partitioned into raw natural gas and liquid storage tank sources using gas and headspace composition data, respectively, and observed enhancement ratios. We also estimate methane emissions based on typical ethane-to-methane ratios in gaseous emissions. The median emission rate from raw natural gas sources in the shale, calculated as a percentage of the total produced natural gas in the upwind region, was 0.7 % with an interquartile range (IQR) of 0.5–1.3 %, below the US Environmental Protection Agency's (EPA) current estimates. However, storage tanks contributed 17 % of methane emissions, 55 % of ethane, 82 % percent of propane, 90 % of n-butane, and 83 % of isobutane emissions. The inclusion of liquid storage tank emissions results in a median emission rate of 1.0 % (IQR of 0.7–1.6 %) relative to produced natural gas, overlapping the current EPA estimate of roughly 1.6 %. We conclude that emissions from liquid storage tanks are likely a major source for the observed non-methane hydrocarbon enhancements in the Northern Hemisphere.

Mantle and crustal gases of the Colorado Plateau: Geochemistry, sources, and migration pathways

The Colorado Plateau hosts several large accumulations of naturally occurring, non-hydrocarbon gases, including CO2, N2, and the noble gases, making it a good field location to study the fluxes of these gases within the crust and to the atmosphere. In this study, we present a compilation of 1252 published gas-composition measurements. The data reveal at least three natural gas associations in the field area, which are dominated by hydrocarbons, CO2, and N2+He+Ar, respectively. Most gas accumulations of the region exhibit compositions that are intermediate between the three end members. The first non-hydrocarbon gas association is characterized by very high-purity CO2, in excess of 75 mol% (hereafter, %). Many of these high-purity CO2 fields have recently been well described and interpreted as magmatic in origin. The second non-hydrocarbon gas association is less well described on the Colorado Plateau. It exhibits He concentrations on the order of 1–10%, and centered log ratio biplots show that He occurs proportionally to both N2 and Ar. Overall ratios of N2 to He to Ar are ≈100:10:1 and correlation in concentrations of these gases suggests that they have been sourced from the same reservoir and/or by a common process. To complement the analysis of the gas-composition data, stable isotope and noble-gas isotope measurements are compiled or newly reported from 11 representative fields (previously published data from 4 fields and new data from 7 fields). Gas sampled from the Harley Dome gas field in Utah contains nearly pure N2+He+Ar. The various compositional and stable and noble gas isotopic data for this gas indicate that noble gas molecule/isotope ratios are near crustal radiogenic production values and also suggest a crustal N2 source. Across the field area, most of the high-purity N2+He+Ar gas accumulations are associated with the mapped surface trace of structures or sutures in the Precambrian basement and are often accumulated in lower parts of the overlying Phanerozoic sedimentary cover. The high-purity gas association mostly occurs in areas interior to the plateau that are characterized by a narrow range of elevated, moderate heat flow values (53–74mW/m2) in the ancient (1.8–1.6Ga) basement terranes of the region. Collectively, the geochemical and geological data suggest that (1) the N2+He+Ar gas association is sourced from a crustal reservoir, (2) the gas association migrates preferentially along structures in the Precambrian basement, and (3) the sourcing process relates to heating of the crust. Prospecting for noble-gas accumulations may target areas with elevated Cenozoic heat flow, ancient crust, and deep crustal structures that focus gas migration. High-purity CO2 gas may also migrate through regional basement structures, however, there is not always a clear spatial association. Rather, CO2 accumulations are more clearly associated with zones of high heat flow (>63mW/m2) that sit above hot upper mantle and are proximal to Cenozoic volcanic rocks near the plateau margins. These observations are consistent with previous interpretations of a magmatic gas source, which were based on geochemical measurements.

Analysis of gas jetting and fumarole acoustics at Aso Volcano, Japan

The gas-thrust region of a large volcanic eruption column is predominately a momentum-driven, fluid flow process that perturbs the atmosphere and produces sound akin to noise from jet and rocket engines, termed “jet noise”. We aim to enhance understanding of large-scale volcanic jets by studying an accessible, less hazardous fumarolic jet. We characterize the acoustic signature of ~2.5-meter wide vigorously jetting fumarole at Aso Volcano, Japan using a 5-element infrasound array located on the nearby crater. The fumarole opened on 13 July 2015 on the southwest flank of the partially collapsed pyroclastic cone within Aso Volcano's Naka-dake crater and had persistent gas jetting, which produced significant audible jet noise. The array was ~220m from the fumarole and 57.6° from the vertical jet axis, a recording angle not typically feasible in volcanic environments. Array processing is performed to distinguish fumarolic jet noise from wind. Highly correlated periods are characterized by sustained, low-amplitude signal with a 7–10Hz spectral peak. Finite difference time domain method numerical modeling suggests the influence of topography near the vent and along the propagation path significantly affects the spectral content, complicating comparisons with laboratory jet noise. The fumarolic jet has a low estimated Mach number (0.3 to 0.4) and measured temperature of ~260°C. The Strouhal number for infrasound from volcanic jet flows and geysers is not known; thus we assume a peak Strouhal number of 0.19 based on pure-air laboratory jet experiments. This assumption leads to an estimated exit velocity of the fumarole of ~79 to 132m/s. Using published gas composition data from 2003 to 2009, the fumarolic vent area estimated from thermal infrared images, and estimated jet velocity, we estimate total volatile flux at ~160–270kg/s (14,000–23,000t/d).

Estimation of fracture height growth in layered tight/shale gas reservoirs using flowback gas rates and compositions–Part II: Field application in a liquid-rich tight reservoir

While hydraulic fracturing is the key to unlocking the potential of unconventional low-permeability hydrocarbon resources, challenges remain in the monitoring of subsurface propagation of fractures and the determination of which geologic intervals have been contacted. This is particularly challenging for wells that are completed in multiple hydraulic fracture stages (multi-fractured horizontal wells or MFHWs) where fracture spacing may be very close and fracture geometry complex. Understanding the fracture extent is important not only for assisting with hydraulic fracture design, but also for mitigating unwanted fracture growth into non-target geologic intervals that do not contain hydrocarbons (e.g. zones with high water saturation). Popular current technologies used for hydraulic fracture surveillance include microseismic (surface and subsurface monitoring) and tiltmeter surveys. While these methods have proven useful for characterizing the extent of created hydraulic fractures, they do not necessarily lead to an understanding of what portions of the geologic section (bounding and target intervals for MFHWs, for example) are in direct hydraulic communication with the well.A solution for establishing the extent of hydraulic fracture growth from target to bounding zones is to first obtain a fluid composition fingerprint of those intervals while drilling through them, and then compare these data with fluid compositions obtained from flowback after hydraulic fracturing. In the current work, a MFHW completed in a liquid-rich tight reservoir is used to test this novel concept. Gas samples extracted from the headspace of isojars® containing cuttings samples, obtained during drilling of the MFHW well, were used to geochemically fingerprint geologic intervals through which the well was drilled. The cuttings samples were collected at high frequency in the vertical, bend and lateral sections of the well over a measured depth range of 4725 ft (1440 m). A compositional marker was identified in the bend of the horizontal well above which the average methane to ethane (C1/C2) ratio was 15.7, versus 2.6 below it. The flowback gas compositions were observed to be intermediate (average C1/C2 = 7.4) between the reservoir above and below the marker, suggesting fracture height grew above the compositional marker.In order to estimate fracture height growth from the geologic interval and flowback compositions, a compositional numerical simulation study was performed. An innovative approach was used to estimate recombined in-situ fluid compositions, on a layer-by-layer basis, by combining the cuttings gas compositional data with separator oil compositions. The resulting numerical simulation model, initialized through use of the layered fluid model and a detailed geological model developed for the subject well and offset drilling locations, was used to history match flowback rates, pressures and gas compositions. The gas compositions of the fingerprinted geologic intervals were therefore employed as a constraint on fracture height growth, estimated in the model to be 175 ft (53 m, propped height). However, because of the uncertainty in model input parameters, a stochastic approach was required to derive a range in hydraulic fracture properties.The current study demonstrates for the first time that it is possible to constrain fracture height growth estimates from flowback data, combined with gas compositional data obtained from cuttings data, provided that the geochemical fingerprints are distinct.

The effect of magmatic intrusions on coalbed methane reservoir characteristics: A case study from the Hoskissons coalbed, Gunnedah Basin, Australia

Magmatic intrusions can deteriorate coalbed methane reservoir quality by precipitating minerals in natural fracture and cleat system. To date, the effect of magmatic intrusions on coal rank and maturity has been studied extensively. However, their impact on fluid flow capacity and gas content is poorly investigated. This study evaluates the impact of magmatic intrusions on reservoir characteristics of the Hoskissons coal interval in the Gunnedah Basin (eastern Australia) where numerous coal-intrusion associations exist. Drill stem test (DST), borehole image logs and core data are used to determine fluid flow characteristics, gas content and quality in 14 wells across the Gunnedah Basin. The integration of borehole image logs and DST data analysis enables us to determine the existence, openness, and hydraulic conductivity of natural fracture and cleat systems in the Hoskissons coal interval. In addition, available desorption canister data, gas composition data, and conventional well logs are interpreted to investigate probable thermal effect on gas content.Our analyses of different datasets reveal that the thickness of intrusions and their positions with respect to the Hoskissons coal interval are variable in the studied wells. Permeability varies from 1091mD down to zero owing to heterogeneous fracture and cleat systems. Interpreted natural fracture/cleat systems are well correlated with measured permeability from DST data analysis. This highlights the role of open natural fractures/cleats in fluid flow characteristics of the Hoskissons coal interval. Results indicate that the mineralizing effect of hydrothermal fluids derived either from magmatic intrusions or coal itself is not a controlling factor in fluid flow capacity of the Hoskissons coal interval in the studied wells. This is described by either the distance between coal section and major intrusions in some wells or perhaps emplacement of intrusive bodies prior to development of cleat and natural fracture networks. The destructive impact of intrusions on permeability is observed in one of the studied wells in which in-situ stress perturbation is large (due to presence of magmatic intrusions in sedimentary rocks). Variable in-situ stress orientation can decrease fracture connectivity and consequently fluid flow properties are affected. Gas content largely varies in heat affected coal intervals. This signature is the result of thermal effect fading with distance and is more pronounced when intrusions are in close proximity to coal intervals. Gas composition is variable in the studied wells. Gas composition data indicate that high quality desorbed gas with methane concentration higher than 90% could be found even in coal intervals which are heavily intruded.

Changes to the volcanic outgassing mechanism and very-long-period seismicity from 2007 to 2011 at Mt. Asama, Japan

Volcanic gases can provide significant information on the state of magma, which is important for interpreting and predicting volcanic activity. We present a study of the seismicity and volcanic gases from Mt. Asama, Japan from 2007 to 2011 to elucidate the change in the mechanism of volcanic gas supply for very-long-period (VLP) seismic events. Two types of degassing occur at Mt. Asama: persistent degassing and a gas burst (ash-free eruption) following a VLP seismic event. We used the linear relationship between the seismic moment and sulfur dioxide (SO2) emissions, and seismic records to estimate the quantity of SO2 gas in the ash-free eruption, which causes the VLP seismic events. The amount of SO2 and volcanic gas composition data were used to calculate the amount of volcanic gases, including H2O, CO2, and other species. We compared the volcanic gas emission rates of ash-free eruptions (eruptive gas emission rates) and total volcanic gas emission rates including the persistent degassing. The ratio of the eruptive gas emission rate to the total gas emission rate (eruptive/total gas ratios) showed a drastic change with eruption. An increase occurred immediately before the 2008 and after the 2009 eruptions. The VLP seismic events are likely caused by sudden outgassing at a shallow depth that is induced by the propagation of the gas phase expansion and rupture. We suggest that the rates of sudden outgassing are controlled by the distribution of gas phases in the conduit. The variability of the eruptive gas emission rates suggests changes in the gas phase distribution in the conduit.

Effect of Slag Composition on Reaction Kinetics of Carbon Composite Agglomerate in the Temperature Range of 1273 K to 1573 K (1000 °C to 1300 °C)

To effectively use high Al2O3 iron ore in carbon composite agglomerate (CCA) reduction process, the effect of slag composition on the isothermal reaction kinetics of CCA was investigated between 1273 K and 1573 K (1000 °C and 1300 °C). Reduction of the particular oxide by CO and gasification reactions of the carbon by CO2 were separately measured by quadruple mass spectrometry gas analysis. To better understand the reaction kinetics, the conventional unimolecular reaction model was modified to get two rate equations for reduction and gasification controls with the reaction thermodynamic driving force incorporated. Based on the gas composition data and modified kinetic model, the rate-controlling steps of CCA at various temperatures and reaction stages were determined. In case, the gasification reaction controls the overall reaction, CaO-Al2O3 Slag increased the reaction rate by accelerating the gasification reaction while CaO-SiO2 Slag decreased the rate by retarding the gasification. As the reduction reaction became dominant in controlling the overall reaction, the addition of slag component had adverse effect on the rate although such effect diminished at higher temperature. Finally, the activation energy values calculated by conventional unimolecular reaction model were compared with those evaluated by modified model. It was found that the gas composition data during the course of reaction and the modified model are of great value in interpreting the reaction kinetics when the controlling reaction is changed over with temperature and reaction time. This study is helpful to understand the theoretical aspects on the usage of high Al2O3-based iron ores for DRI production.

Estimation of greenhouse gas flux from mud volcanoes in the Dushanzi area, southern Junggar Basin of Northwest China

Mud volcanoes are a direct manifestation of deep tectonic and subsurface fluid invasion activities near the earth surface. Such activity emits large amounts of greenhouse gases, predominantly methane, and is also responsible for an important part of the total geologic carbon flux to the atmosphere. However, there is little research on estimation of greenhouse gas flux from mud volcanoes in China. The mud volcanoes in the Dushanzi area of the Xinjiang Uygur Autonomous Region are typical and very active, emitting various types of greenhouse gases. We used a sealed chamber connected to a methane detector to measure the <italic>in situ</italic> gas emission rate and estimate flux. Based on well-known research methods, experience with greenhouse gas emissions from mud volcanoes abroad, and gas composition data, we estimated total flux of those gases emitted from the Dushanzi mud volcanoes. Greenhouse gas fluxes from macro-seeps in areas DSZ-01 and DSZ-03 exceeded 161 t/a. Flux by micro-seepage in areas DSZ-01 (314 m²), DSZ-02 (8400 m²), and DSZ-03 (314 m²) was 16.6 t/a.

Influence of total organic carbon deposition on the inventory of gas hydrate in the Indian continental margins

Total organic carbon (TOC) content of marine sediments represents residual carbon, originally derived from terrestrial and marine sources, which has survived seafloor and shallow subseafloor diagenesis. Ultimately, its preservation below the sulfate reduction zone in marine sediments drives methanogenesis. Within the gas hydrate stability zone (GHSZ), methane production along continental margins can supersaturate pore fluids and lead to the formation of gas hydrate. In this paper we examine the inventory and sources of TOC in sediments collected from four regions within the GHSZ along the Indian continental margins. The recovered sediments vary in age from Oligocene to recent. Mean TOC abundance is greatest in the Krishna–Godavari (K–G) Basin and decreases progressively to the Mahanadi basin, Andaman wedge, and Kerala–Konkan (K–K) Basin. This decrease in TOC is matched by a progressive increase in biogenic CaCO3 and increasing distance from terrestrial sources of organic matter and lithogenic materials. Organic carbon sources inferred from C/N and δ13CTOC range from terrestrial (K–G Basin) to mixed marine and terrestrial (Mahanadi Basin), to marine dominant (Andaman wedge and K–K Basin). In the K–G Basin, variation in the bulk δ13CTOC is consistent with changes in C3 and C4 vegetation driven by monsoon variability on glacial-interglacial timescales, whereas in the Mahanadi Basin a shift in the δ13CTOC likely reflects the onset of C4 plant deposition in the Late Miocene. A large shift the δ13CTOC in the K–K basin is consistent with a change from C3 to C4 dominated plants during the middle Miocene. We observe a close relationship between TOC content and gas hydrate saturation, but consider the role of sedimentation rates on the preservation of TOC in the zone of methanogenesis and advective flow of methane from depth. Although TOC contents are sufficient for in situ methanogenesis at all the sites where gas hydrates were observed or inferred from proxy data, seismic, borehole log, pressure core, and gas composition data coupled with relatively high observed gas hydrate saturations suggest that advective gas transport may also play a role in the saturation of methane and the formation of gas hydrates in these regions. Although TOC content may be a first order indicator for gas hydrate potential, the structural and stratigraphic geologic environment along a margin will most likely dictate where the greatest gas hydrate saturations will occur.

Experimental and modeling study of pinewood char gasification with CO2

The objective of this study is to measure apparent rate parameters for pinewood char gasification with CO2 using large particles with relevance to practical gasifiers. The novel features of this work include: (1) char gasification for CO2 recycling, which is studied less in the past than char gasification in other environments, (2) independent measurements involving gravimetric analyses and product gas composition gas chromatography, (3) detailed uncertainty analyses of both methods to report resulting uncertainties in kinetic rate constants, and (4) investigation of the char structure development and its role in gasification. A fixed-bed reactor providing a slip-velocity of 0.12m/s gasifier and control of the bed temperature to within ±10K at 1000–1170K is used. A low-ash (<0.01wt.%) pinewood char is selected to minimize the catalytic effects of ash on mass-loss rates. The char is prepared by heating pinewood sawdust in an electrical furnace to a temperature of 1100K. Gravimetric and product gas composition data are interpreted using the volumetric, non-reactive core and random pore models. The results show that the activation energies corresponding to these models are 217±6, 186±13, 125±30kJ/mol respectively. The random pore model shows the closest agreement with the experimental data, despite the uncertainties in the measured activation energies. The estimated random pore model structure parameter Ψ increases from 0 to 16.5 with increases in the gasification temperature. Measurements of BET surface area show significant increase with char conversion. The results of this study show that the apparent gasification rate parameters for relatively large particles of practical relevance are comparable to those obtained from laboratory studies with much smaller particles.