Dissolution Of Gases In Water Research Articles

An estimation of gas volume in the water-saturated part of Cenomanian gas reservoirs: a case study of the Medvezhye oil and gas condensate field

The amount of remaining recoverable natural gas reserves is affected by the pinching of gas reserves by infiltrating water and degassing of formation water in the Cenomanian water-pressure complex. It is necessary to reliably determine the volume of gas-saturated water in order to estimate the volume of gas dissolved in produced water. The area of the gas-oil contact is determined by known methods, but the height of the reservoir zone, represented by gas-saturated water (transition zone), must be specified.The fluid distribution and the structure of the transition zone depend on gravitational and capillary forces. These forces depend on the physical and chemical properties of the gas and formation water, as well as the composition and filtration properties of the reservoir. To calculate the thickness of the reservoir in which the process of gas dissolution in water takes place, it is proposed to consider it from the point of view of molecular diffusion processes.The authors of the article propose an adapted VNIIGAZ method for determining the transition zone and the volume of water in which gas from underground gas storages is dissolved (a case study of the Medvezhye oil and gas condensate field). The proposed method for calculating the volume of gas dissolved in formation waters of Cenomanian gas deposits, taking into account diffusion, showed an acceptable result. The proposed method for calculating the volume of gas dissolved in formation waters of Cenomanian gas deposits, taking into account diffusion, gave an acceptable result.

The Study on the Dissolution Process of Oxygen and Nitrogen in Gas-Soluble Water

In air flotation process, different gas produce different gas content of gas-soluble water. According to the difference of solubility of nitrogen and oxygen in water, the affect of the difference of molecule structures between nitrogen and oxygen on their solubility in water was discussed in the paper. Then, Two types of gas dissolution in water was introduced in the paper---gap filling and hydration. The concept of effective gap degree was proposed. And According to the effective gap degrees and hydration coefficient of nitrogen and oxygen, the change rules of the dissolved amount of oxygen and nitrogen by each type of dissolution at different temperature were obtained through a series of data fitting calculation by using Matlab. Finally, the reason for the change of the amount of gap filling and hydration in gas-soluble water caused by temperature change was also analyzed in the paper.

Agreed discoveries: students’ negotiations in a virtual laboratory experiment

This paper presents an analysis of the scientific reasoning of a dyad of secondary school students about the phenomenon of dissolution of gases in water as they work on this in a simulated laboratory experiment. A web-based virtual laboratory was developed to provide learners with the opportunity to examine the influence of physical factors on gas solubility in water. An evaluation process involving 180 students revealed that the concepts connected to the dissolution of gas in water caused problems for the students even after having experimented with the virtual laboratory. To investigate the nature of learners’ reasoning about the visualised events, 13 video-recorded groups of learners were analysed. This study follows the reasoning of one group that displayed a possibly productive way of solving the problem. The results address the students’ general difficulty of discovering something that they are conceptually unprepared for within the virtual laboratory. The analysis shows how the students eventually found a way out of their dilemma by making an analogy with other dissolving processes. In effect, the analysis elucidates some of the analytical work that had to be done by the participants when collaboratively negotiating a shared meaning of a scientific concept in concord with a given task and set of instructional materials. Implications for design might be to provide the learning material with explicit hints that enable students to connect to specific phenomena related to the one investigated concept. The findings show the usefulness of video analytic research, informed by CA and ethnomethodology. This analytical framework can support design processes and provide useful information, which might identify hurdles to learning a scientific concept by simulated events and pathways to overcome these hurdles.

Hydrothermal processes governing the geochemistry of the crater fumaroles at Mount Etna volcano (Italy)

We investigated the geochemistry of the fumaroles at the summit area of Mt. Etna, including sulfur speciation and the content of acidic gases. The carbon-isotope composition of the Etnean plume was also measured in order to compare it to that of fumaroles. Two types of fumaroles were identified: (i) low-temperature fumaroles, which are dominated by CO 2 with minor amounts of SO 2 and H 2S, and negligible chlorine contents, and (ii) high-temperature fumaroles, which are strongly air-contaminated and characterized by appreciable amounts of volcanogenic carbon, sulfur, and chlorine. As recognized by Martelli et al. (2008), both groups of fumaroles are fed by the degassing of an underlying magma; nevertheless, compositional data clearly show that secondary processes affect the composition of the fluids once they leave the magma body. Here a model of cooling and condensation of fluids is proposed to explore such postmagmatic processes. The model, which uses Etnean plume geochemistry as starting composition of fluids exsolved from magma, shows that SO 2 and H 2S control the redox conditions of the gas mixture during the cooling, until the reactions involving CO/CO 2 and H 2/H 2O ratios are fully quenched at temperatures around 350–450 °C. The dissolution of gases in water, subsequent to condensation, must occur at thermobaric conditions over 50 bar and 260 °C, which allows (a) total removal of HCl, (b) partial removal of sulfur species while preserving the SO 2/H 2S ratio, and (c) the C/S ratio to increase by almost 10-fold relative to that in the plume. The observed CH 4/CO 2 ratios are higher than those calculated for the Etnean magmatic gas, and hence they provide evidence of modest contributions from peripheral hydrothermal fluids during the migration of magmatic gases toward the surface in both low- and high-temperature fumaroles. Due to the peculiar thermodynamic conditions, the model predicts that carbon isotopes do not experience any postmagmatic fractionation, and hence the isotopic composition of the fumaroles is representative of magmatic carbon. Measurements of the carbon-isotope composition of the plume corroborate these findings.

Characteristics of microbubbles generated by porous mullite ceramics prepared by an extrusion method using organic fibers as the pore former

Porous mullite ceramics with unidirectionally oriented pores were prepared by an extrusion method using rayon fibers as the pore formers and the characteristics of microbubbles generated by these porous ceramics were investigated. The 1200 mm long ceramics were tubular and of thick or thin types of 20–30 mm inner diameter and 30–50 mm outer diameter, respectively. The thin and thick samples had porosities of 47 and 49% and average pore radii of 7.8 μm. The gas permeabilities of the thick and thin samples were 4.1 × 10 −14 and 5.4 × 10 −14 m 2, respectively. Microbubbles were generated by introducing N 2 gas through the ceramic tube by immersing it into water. The minimum pressure (bubble point pressure) for generation of microbubbles was 20 kPa, much lower than for other bubble-forming methods. The average microbubble radii ranged from about 70 to 105 μm at flow rates of 0.15–0.25 L/min in the thin sample and 0.3–0.7 L/min in the thick sample. These bubble sizes are much smaller than calculated for a Fritz-type bubble such as generally formed by bubbling from pores and/or orifices. However, the present bubble sizes agree well with the calculated value based on nanobubbles, indicating that bubble formation occurs by mixing the gas with water in small pores. Since microbubbles enhance the dissolution rate of a gas phase in water, they are potentially useful for improving water environments, especially oxygen-deficient water. The effectiveness of gas dissolution in water was confirmed by determining the dissolution behavior of CO 2 gas using these porous ceramics.

Thermodynamics of Non-Reactive Gases Dissolved in Water at Ambient Temperature (T≤333 K): an Update

The thermodynamics of dissolution of non-reactive gases in water under ambient conditions is of importance for the description of the properties of small hydrophobic solutes, and they are also of interest for environmental assessments. The review published in 1977 by Wilhelm, Battino and Wilcock (Chem. Rev. 77:219–262, 1977) constitutes a milestone in this field. However, a number of new data have been published since then, including both solubility and calorimetric determinations. We have analyzed the new data for 27 binary systems reported in the literature at the time of writing this article. Whenever solubility and calorimetric data both exist they have been fitted together. There are, however, systems for which only one type of new thermodynamic information is available; these systems were also analyzed using procedures that are described in this work.

Thermodynamics of micelle formation in water, hydrophobic processes and surfactant self-assemblies

The critical micelle concentration (c.m.c.) for four cationic surfactants, alkyl-trimethyl-ammonium bromides, was determined as a function of temperature by conductivity measurements. The values of the standard free energy of micellisation DeltaG degrees(mic) at different temperatures were calculated by using a pseudo-phase transition model. Then, from the diagram (-DeltaG degrees(mic)/T)=f(1/T), the thermodynamic functions DeltaH(app) and DeltaS(app) were calculated. From the plots DeltaH(app)=f(T) and DeltaS(app) = f(ln T) the slopes DeltaC(p) = n(w(H))C(p,w) and DeltaC(p)=n(w(S))C(p,w) were calculated, with the numbers n(w(H)) and n(w(S)) negative and equal and therefore defined simply as n(w). The number n(w)<0, indicating condensed water molecules, depends on the reduction of cavity that takes place as a consequence of the coalescence of the cavities previously surrounding the separate aliphatic or aromatic moieties. The analysis, based on a molecular model consisting of three forms of water, namely W(I), W(II), and W(III), respectively, was extended to several other types of surfactants for which c.m.c. data had been published by other authors. The results of this analysis form a coherent scheme consistent with the proposed molecular model. The enthalpy for all the types of surfactant is described by DeltaH(app)= -3.6 + 23.1xi(w)-xi(w)C(p,w)T and the entropy by DeltaS(app)= +10.2+428xi(w)-xi(w)C(p,w) ln T where xi(w)= |n(w)| represents the number of molecules W(III) involved in the reaction. The term Deltah(w)= +23.1 kJ mol(-1) xi(w)(-1) indicates an unfavourable endothermic contribution to enthalpy for reduction of the cavity whereas the term Deltas(w)= +428 J K(-1) mol(-1) xi(w)(-1) represents a positive entropy contribution for reduction of the cavity, what is the driving force of hydrophobic association. The processes of non polar gas dissolution in water and of micelle formation were found to be strictly related: they are, however, exactly the opposite of one another. In micelle formation no intermolecular electronic short bond is formed. We propose, therefore, to substitute the term "hydrophobic bond" with that of "hydrophobic association".

Henry's Law Near the Critical Point of Water-Applications in Solvent Co-Injection With SAGD

Abstract In the last 10 years, substantial progress has been made in the theoretical treatment of gas dissolution in water, near the critical point of water (374 °C). An asymptotic behaviour of Henry's law for a variety of gases (the noble gases, methane, ethane, nitrogen, oxygen, carbon dioxide, and hydrogen sulphide) already governs the behaviour of these gases at temperatures above approximately 180 °C, well below the critical point. This behaviour has been used to develop a theory of gas production in SAGD, according to which gas production in SAGD largely occurs via dissolution of gas in the steam condensate. Further recent developments in this area of solution thermodynamics have extended the knowledge of this phenomenon to various light hydrocarbons, from butane to dodecane, and the aromatics such as benzene and toluene. In the present paper, data for the distribution coefficients (Kvalues) of light hydrocarbon solvents in water are presented, and the application for prediction of solvent returns in SAGD enhanced by solvent co-injection is discussed. Optimal choice of solvent composition to maximize solvent returns is possible. Introduction In 2001, Thimm(1) proposed that gas production in SAGD proceeds via a mechanism whereby gases are dissolved in the produced liquids, and enter the wellbore in that form. No case has been reported so far where it has been necessary to postulate free gas entering the SAGD production well in order to explain the observed GOR and produced gas compositions. Gases are considered to separate from the liquids in the wellbore and facilities. The solubility of gas in a liquid is governed by Henry's Law, which may be stated as: Equation (Available In Full Paper) In 1989, Japas and Levelt Sengers(2) provided the theoretical basis for observations made at that time and since, that for all solvents- gas pairs, the distribution coefficients for gases in general declines as the critical point of the solvent is approached. In fact, Japas and Levelt Sengers showed that all values of K approach unity towards the critical point. In the case of water, this asymptotic behaviour governs gas solubilities above 180 °C or so, and maybe considerably earlier in the case of some gases. Harvey and Levelt Sengers(3) published a power law for a variety of gases in water, valid between the triple point and the critical point of water: Equation (Available In Full Paper) For the case where the solvent is water, all values of density and also the fugacity term in this equation may be found in or derived from steam tables. The values of A, B, and C are published by Harvey and Levelt Sengers. Other authors have published coefficients of the same kind, notably Suleimenov and Krupp(4) for hydrogen sulphide. Thimm(1) has shown that this approach, when applied to simulated oil and water production forecasts in SAGD or to actual production data, yields GOR and produced gas composition data in good agreement with actual results. Such data have been published previously(5, 6).

Retention in hydrophobic interaction chromatography and dissolution of nonpolar gases in water

The retention data of dansyl amino acids in hydrophobic interaction chromatography (HIC) is interpreted in terms of physicochemical properties of the eluites and solvent and the results are compared to data for the dissolution in water of nonpolar gases. Isothermodynamic temperatures, certain linear relationships between thermodynamic quantities and molecular structure as well as the hermeneutics of the solvophobic theory are employed for data analysis. van't Hoff plots of the retention data with dansyl amino acids are curved and intersect at the isoenergetic temperature, indicative of enthalpy-entropy compensation. The isoenthalpic and isoentropic temperatures are also evaluated and the three isothermodynamic temperatures are found to fall in the same narrow ranges as those for the dissolution of gases in water. Plots of thermodynamic quantities for the retention in HIC against the nonpolar molecular area are linear and thus allow the evaluation of enthalpy, entropy, Gibbs energy and heat capacity changes per unit nonpolar surface area of dansyl amino acids. By employing the solvophobic theory thermodynamic expressions are derived in terms of the nonpolar molecular area and interfacial tension. Using these expressions and n-heptane as model compound it was found that the above group molecular parameters are nearly identical for the retention in HIC and the dissolution of gases in water, thus confirming the mechanistic identity of the two processes.