Substantial Amounts Of Gas Research Articles

Identification and Quantitation of Aerosol Products of the Reaction of β-Pinene with NO3 Radicals and Implications for Gas- and Particle-Phase Reaction Mechanisms.

Substantial amounts of gas- and particle-phase organic nitrates have been reported in field studies of atmospheric chemistry conducted around the world, and it has been proposed that a significant fraction of these may be formed from the nighttime reaction of monoterpenes with NO3 radicals. In the study presented here, β-pinene (a major global monoterpene emission) was reacted with NO3 radicals in an environmental chamber and the molecular and functional group composition of the resulting secondary organic aerosol (SOA) was determined using a variety of methods. Eight products, which comprised ∼95% of the SOA mass, were identified and quantified. More than 90% (by mass) of these consisted of acetal heterodimers and heterotrimers that were apparently formed through acid-catalyzed reactions in phase-separated particles. The molar yield of the major oligomer was 16.7%, and the yields of the other six and the single monomer ranged from 1.1% to 2.9%, for a total yield of 30.7%. From these analyses it was determined that the yields of the two major monomer building blocks were 25.9% and 23.6%, and that those of the other four ranged from 2.0% to 4.8%, for a total monomer yield of 62.4%. The measured SOA mass yield was 88.9% and the O/C, N/C, and H/C ratios, molecular weight, and density of the SOA calculated from the results of functional group analysis of the bulk SOA were 0.40, 0.11, 1.79, 217 g mol-1, and 1.21 g cm-3, respectively, similar to values estimated from results of molecular analysis. The results demonstrate the combined importance of RO2• + RO2• reactions, alkoxy radical decomposition and isomerization, and acid-catalyzed particle-phase reactions in the NO3 radical-initiated oxidation of β-pinene and subsequent formation of SOA and should be useful for understanding reactions of other monoterpenes and for developing models for the laboratory and atmosphere.

Equipo de fusión al vacío para la determinación cuantitativa del gas atrapado en piezas fundidas

Parts manufactured with casting processes may trap substantial quantities of gas, which could harm the mechanical properties of the manufactured parts. In this work, a vacuum melting device manufactured to measure trapped gas in castings is described. Adjustment correlations, which accurately calculate trapped gas quantity as a function of the pressure increments measured by the vacuum equipment, are obtained. Finally, as an application of the equipment, we present the results obtained for several parts manufactured using a pressure die casting machine. It is expected that the vacuum melting device will be useful to optimize the operating conditions which reduce the trapped gas in casting processes.

Type Curves for Dry CBM Reservoirs With Equilibrium Desorption

Abstract The purpose of this work is to model the single-phase radial gas flow in coalbed methane including equilibrium sorption phenomena in the coal matrix and Darcy flow in the natural fracture network. Considering a control volume, the gas desorption rate as a function of time and space is incorporated into the radial continuity equation as a source term. Using a Langmuir-type sorption isotherm, the gas desorption rate is determined at any radius of the reservoir. Introducing the definition of pseudo-pressure and pseudo-time, the resulting continuity equation is converted into the linearized diffusivity equation by modification of total gas compressibility. It is shown how the traditional definition of the material balance pseudo-time is modified for dry CBM reservoirs. With the help of these transformations, the traditional (PTA and RTA) type curves can be employed for analysis of production data of dry CBM reservoirs. The model developed here is validated against Fekete's numerical CBM simulator over a wide range of reservoir parameters. In addition, one set of field data from Horseshoe Canyon coals of the Western Canadian Sedimentary Basin is analyzed using the solution procedure presented in this paper. Introduction Coalbed methane (CBM) is natural gas produced from coal seams. Coal is both the source rock and the reservoir for methane production. The world total CBM resource potential is evaluated at about 143.2 trillion cubic metres(1). CBM reservoirs are naturally fractured reservoirs that are characterized by two distinct porosity systems including:micropores (matrix) with extremely low permeability andmacropores (natural fractures or cleats). Due to the small pore diameter of less than 10 Å, the coal matrix has a large internal surface area of 100 to 300 m(2)/g(2, 3). As a result, substantial quantities of gas can be adsorbed on the surface of the coal grains. Micropores are impermeable to gas and inaccessible to water. However, the desorbed gas can be transported through the primary porosity system by diffusion. The macropores act as a sink to the micropores and provide permeability to fluid flow. In porous media with larger pore size distributions, mass transfer is driven by pressure gradients, whereas in coal, mass transfer is driven by concentration gradients(4, 5). The diffusion through the micropores can be the result of three distinct mechanisms that may act individually or simultaneously(6):bulk diffusion, where molecule/molecule interactions dominate;Knudsen diffusion, where molecule/surface interactions dominate; andtwo-dimensional surface diffusion of the adsorbed gas layer. The steady state diffusion coefficient of methane for most coals is on the order of 10−4 to 10−5 cm(2)/s(6). These experimentally determined diffusion coefficients represent averaged values including the contributions of the bulk, Knudsen and surface diffusion processes. Diffusion effects can be quantified by determining a sorption time. The sorption time is equal to the time required to desorb 63.2% of the initial gas volume. It is determined from whole core canister desorption test. This time is related to fracture spacing and the diffusion coefficient(7). Gas production from the CBM reservoirs is controlled by a four-step process that includes:

Gas-Phase Mass Transfer Processes in Landfill Microbiology

This report assesses gas-phase mass transfer processes in landfills with respect to their influence on waste biodegradation. Gas-phase transport must dominate in many regions of the waste because aqueous-phase transport is restricted, the environment is largely unsaturated, and substantial quantities of gas are produced. Analysis of landfill gas and landfill gas condensate at four municipal solid waste landfills in the eastern United States demonstrated that both volatile fatty acids and microorganisms are transported in the gas phase. The heterogeneity, mass transfer limitations, and significant thermal gradients in waste environments imply that gas-phase processes can play crucial roles in waste decomposition, for example by regulating local pH and distributing trace nutrients. A conceptual framework describing these processes is presented. Implications for waste management, landfill design, energy production, air emissions, and anaerobic microbiology are discussed.

Methane Pressure-Cycling Process With Horizontal Wells for Thin Heavy-Oil Reservoirs

Summary The methane pressure-cycling (MPC) process is an enhanced-oil-recovery (EOR) scheme intended for application in some heavy-oil reservoirs after termination of either primary or waterflood production. The essence of the process is the restoration of the solution-gas-drive mechanism. The restoration is accomplished by re-injecting an appropriate amount of solution gas (mainly methane) and then repressuring the gas back into solution by injecting water until approximate original reservoir pressure is reached. This, aside from the replacement of produced oil by water, recreates the primary-production conditions. This novel recovery technique is being developed to target the considerable portion of heavy-oil resources located in thin reservoirs. Primary and secondary methods have managed to recover at best 10% of the initial oil in place (IOIP). Heat losses to overburden and underburden or bottomwater zones make thermal methods unsuitable for thin reservoirs. Sandpack-flood tests in 30.5-cm (length)×5.0-cm (diameter) sandpacks were carried out for oils with a range of dead-oil viscosities from 1700 to 5400 mPa·s. The results showed that the pressure-cycling process could create a favorable condition for recharged gas to contact the remaining oil in reservoirs. This restores the situation whereby substantial amounts of gas are in solution for further "primary" production. The effects on the efficiency of the MPC process of cycle termination strategy, oil viscosity, and mobile-water saturation were investigated. Simulations were conducted to investigate the MPC process in three heavy-oil reservoirs in Saskatchewan, Canada. The effects on the process of infill wells, oil viscosity, gas-injection rate, and the presence of wormholes in reservoirs were studied.

The absence of diffuse degassing at Popocatépetl volcano, Mexico

Soil gas or flux measurements have shown that many active volcanoes release significant volumes of magmatic gas through their flanks. This type of measurement represents a useful and safer method (compared with direct fumarole measurements) for monitoring an active volcano. However, this study shows that not all volcanoes will have a significant diffuse component, even if substantial quantities of gas are released from the crater. The current phase of volcanic activity at Popocatépetl started in December 1994. Since then, frequent ash emissions have been occurring and very large quantities of SO 2 and CO 2 have been measured in the summit plume: up to 60,000 t day −1 of SO 2. From August 1997 until April 1999 over 500 measurements of Rn and CO 2 in soil gas were performed, with extensive coverage of the volcano. Surprisingly, no CO 2 of magmatic origin has been detected. Levels of up to 14% have been measured in some locations, however, with δ 13C values of between −17‰ and −25‰, its origin appears to be biogenic. The average R/ R a value for the He isotopic ratio of samples of soil gas was 0.49 with all samples giving a radiogenic rather than magmatic signature. Some large ravines in the edifice are thought to mark the location of faults. Large displacements have been measured, but only low concentrations of soil gases were recorded. There is no evidence of a geothermal system, which is likely to be connected to the absence of a diffuse gas component.

WFPC2 Observations of NGC 454: An Interacting Pair of Galaxies

We present Wide Field Planetary Camera 2 images in the F450W, F606W, and F814W filters of the interacting pair of galaxies NGC 454. Our data indicate that the system is in the early stages of interaction. A population of young star clusters has formed around the late component, and substantial amounts of gas have sunk into the center of the earlier component, where it has not yet produced significant visible star formation or nuclear activity. We have photometric evidence that the star clusters have strong line emission, which indicates the presence of a substantial component of hot, massive stars that formed less than 5-10 Myr ago.

Depositional and Diagenetic Controls on Gas Production from Frio (Oligocene) Sands at Monte Christo Field, Hidalgo County, Texas

ABSTRACT Monte Christo Field is located in central Hidalgo County on the Gulf Coastal Plain of south Texas. Depositional and structural factors controlling the accumulation and production of hydrocarbons are related to lateral and vertical facies changes as well as syndepositional growth faulting. These factors combine to compartmentalize the pay sandstones into discrete, isolated reservoirs. Rollover into these growth faults, coupled with greater sandstone thickness and quality at preferred points of delta-front sand deposition, result in a combination of structural and stratigraphic entrapment of gas. Frio reservoir sandstones consist of stacked, upward-coarsening, progradational packages. In each is found a vertical succession of basal abandonment facies, offshore mudstones, distal-delta front sands and silts (lower shoreface), and distributary mouth bar (upper shoreface) sandstones. The upper shoreface sandstones comprise the best reservoir facies. Each facies contains trace fossils indicative of the paleo-environment. Cyclic progradational packages at Monte Christo Field are the direct result of episodic movement along the Mission fault, a large down-to-basin growth fault which bounds the field to the west and parallels depositional strike. Within the study area, three smaller splinter faults bifurcate to the east from the Mission fault and compartmentalize the Frio reservoirs. Diagenetic influences on reservoir quality involve extensive cementation and secondary porosity generation. Reservoir sandstones are fine- and very fine-grained feldspathic litharenites and lithic arkoses. The breakdown of unstable volcanic rock fragments results in significant chlorite and illite grain-coating cements which commonly block pore throats and greatly reduce permeability. Calcite and ferroan carbonate cementation occludes porosity significantly. Minor quartz, potassium feldspar, zeolite and titanium oxide authigenesis are also present. These factors result in relatively low porosities of 10 to 15% and very low permeabilities. The generation of secondary porosity by dissolution of feldspars and carbonate material enhances the diminished pore volume. Point counts reveal that a minimum of 30% of the existing porosity is of secondary origin. Even with significant porosity enhancement in some intervals, artificial fracture stimulation is required to achieve an economic rate of production. This procedure also taps into the substantial quantities of gas trapped in the lowest permeability portions of the reservoir facies.

Absorption Line Studies and the Distribution of Neutral Gas in the Local Interstellar Medium

AbstractPrevious published absorption line studies performed at ultraviolet and visual wavelengths are combined with new ultraviolet data in order to map out the distribution of HI within 150 pc of the Sun. Newly presented data for distances less than 50 pc further support the local cloud model as presented by Bruhweiler (1982). The Sun is embedded, near the edge of a diffuse cloud with total column density of 2 x 1019cm-2. Most observed directions within 50 pc away from the cloud body reveal trace amounts of gas (N)HI) ~ 1018 cm-2) presumably arising in the outer skin of the local cloud. At greater distances (50 ≲ d ≲ 150 pc) most directions show significant absorption with N(HI)>1019 cm-2. Two directions, one toward the northern galactic pole (NGP), the other toward β CMa exhibit unusually low HI column densities out to distances of 150-200 pc. However, substantial amounts of gas, N(HI) > 1019 cm-2, are seen toward the NGP at greater distances. The implications of these results on astronomy at wavelengths shortward of 912Å are discussed.

The enhancement of dark d.c. conductivity by gas adsorption on thin films of macrocyclic copper complexes

Abstract The dark d.c. conductance of thin films of copper complexes of phthalocyanine (α-form), hemiporphyrazine and dihydrodibenzo [b, i] [1, 4, 8, 11] tetra-azacyclotetradecine has been studied in vacuo and in the presence of an extensive range of gases. Only those gases which can be classed as electron acceptors increased the conductance, with NO2/N2O4 (“NOX”) being particularly effective. Spectroscopic evidence is provided to show that the NOX-copper phthalocyanine interaction generates the organic radical cation and NO-2, and that substantial quantities of gas are accumulated within the thin film. A new class of extrinsic organic semiconductor is described.

Generation of Abnormal Pressures Through Organic Matter Transformations: ABSTRACT

In argillaceous and carbonate-evaporite source beds, much of the oil-generating organic matter is concentrated along bedding surfaces (varves and laminae). During the principal phase of oil generation, when adequate thermal energy is available, 25 to 30 wt. % of the original organic matter commonly is converted to liquids, mainly bitumen, with a relatively small percentage of water. Part of the bitumen is then thermally cracked to crude oil before oil expulsion occurs. Substantial amounts of gas, principally hydrocarbons with some CO2 and N2, are also generated. Much of the water and CO2 is generated before oil is formed. The release of fluids from the organic matter causes a reduction in the volume of the residual solid organic matter; however, this volume decrease is offset by the considerably greater volume of the generated fluids. Thus, the volumes of generated products plus residual organic matter represent a substantial net volume increase relative to the volume of the organic matter at the start of significant oil generation. Consequently, very high pressures result locally along the bedding surfaces if the laminae are adequately sealed. Eventually, these localized, transitory, high fluid pressures will develop along the bedding in most parts of the source-rock sequence if the entire source-rock system is sealed and confined. This generated fluid pressure supplements aquathermal pressure caused y thermal expansion of water but is more focused in time and space and is, therefore, a more important factor in internal migration and expulsion than aquathermal pressure. End_of_Article - Last_Page 753------------

Performance Review of Tapered Submergible Pumps in the Three Bar Field

When lifting gaseous fluids with high-volume electric submergible pumps, compensation for compressibility and varying fluid volumes is required for the pump design. This paper describes the successful design and use of the tapered submergible pump for handling dynamic fluids in the Three Bar Field of Texas. Introduction The Three Bar (Devonian) Field waterflood project in Andrews County, TX, currently comprises 37 producing wells and 28 water injection wells. A total of 43 submergible pumps have been installed in 15 Three Bar Unit wells. Thirteen of the wells have used a total of 30 tapered pumps. This paper reviews the design, operation, and performance of these submergible pumps, with emphasis on the tapered submergible pump. Submergible electric centrifugal pumps are used widely as a high-volume artificial lift method. There are many different sizes and types of pumps designed to handle specific volume ranges. A tapered submergible pump is any multistage centrifugal pump that is designed pump is any multistage centrifugal pump that is designed to handle a volume differential between pump intake and discharge, while remaining within optimum efficiency ranges. A single-pump type can handle a limited fluid volume differential. When a required volume differential exceeds the single-type pump's efficiency range, then two or more different stages may be incorporated into one pump. The pumps are assembled with the larger-capacity pump. The pumps are assembled with the larger-capacity stages on the bottom, or the intake, and the smaller-capacity stages stacked above. Although single-type pumps may handle differential volumes, for our purposes only pumps using two or more types in the design hereafter will be designated "tapered" pumps. Fig. 1 illustrates a complete down-hole configuration of this type. On April 23, 1971, the first submergible pump, a tapered pump, was installed in the Three Bar Unit. Since then, submergible pumps have been responsible for recovering an incremental 1.84 million bbl oil more than the replaced rod-pumping equipment. About 66% of this volume was lifted by tapered submergibles. If this highvolume lift had not been introduced and operated successfully, many of these incremental reserves could have been lost because of failure to produce efficiently the volumes of fluid necessary to capitalize on the field's response to waterflooding. Special emphasis on handling substantial quantities of gas with the high-volume lift equipment created the need to apply the tapered submergible pump design. A computer program was used to design the pumps at the Three Bar Unit. program was used to design the pumps at the Three Bar Unit. Although both the tapered concept and the computer-designed procedure are used widely and generally are accepted, this procedure are used widely and generally are accepted, this performance review of the pumps at the Three Bar Unit evaluates performance review of the pumps at the Three Bar Unit evaluates each type in practice. Operating Conditions The Three Bar Unit has experienced excellent waterflooding response, while producing from a Devonian limestone at an average depth of 8,200 ft. The reservoir has two pay zones with a total net thickness of about 70 ft. Both zones are highly fractured and each displays an average porosity of 20%. The crude oil is sweet with a gravity of 41 degrees API, viscosity of 0.371 cp, and bottom-hole temperature of 130 degrees F. The typical Three Bar Unit well under primary recovery was a flowing, high-GOR producer. JPT P. 1781