Model Of Gas Hydrate Formation Research Articles

Diffusion model of gas hydrate formation from ice considering the gas pressure drop

A kinetic model of the process of gas hydrate formation from ice that considers the gas pressure drop caused by this process is presented. This model is based on the diffusion equation. The issues during the formation of gas hydrate from ice powder and that from a flat ice layer are considered separately. For each of these problems, a solution in the framework of a quasi-stationary approximation is obtained, allowing for the calculation of the gas pressure drop in the gas phase. The calculated data are compared with available experimental data on the kinetics of CO2 hydrate formation from pure ice powder and ice powder with the addition of sodium dodecyl sulfate (SDS) at a mass concentration of 240 ppm: the calculated and experimental curves of CO2 pressure drop are compared with each other. From this comparison, the values of the diffusion coefficient of CO2 through a layer of CO2 hydrate formed from pure ice and ice with the addition of SDS at a mass concentration of 240 ppm were determined. Based on these values, it was found that SDS molecules present in the gas hydrate affect the rate of gas diffusion through the gas hydrate layer.

Experimental investigation and modelling of the hydrate formation kinetics based on hydrate pore-scale distribution in porous media

Hydrate technology has a bright future for innovations in water, energy, and environmental applications. A reliable and applicable kinetic model of gas hydrate formation is essential for developing hydrate technology. In this work, the experiments of methane hydrate formation with different water saturation SA are conducted in the Cubic Hydrate Simulator (CHS), where the pressure profile and temperature distribution are measured. A new kinetic model integrating hydrate pore-scale distribution is established, assuming that the reaction area AS is controlled by the aqueous phase surface area along the gas-soluble direction. This new model is employed to replicate the experimental process numerically by the history-matching method, and the intrinsic reaction rate constant K0 is determined to be 850.0 mol/m2/Pa/s. In addition, we quantitatively distinguish the characteristics of the water pore-scale distribution in the excess-water, cementing-water, and excess-gas environments. The new model has been validated to be more excellent than those with four currently available models for the hydrate formation, and the sensitivities of the kinetic parameters are discussed in detail. The results show that the spatial distributions of the temperature T and hydrate saturation SH spatial distribution are heterogeneous in CHS due to the phase change and heat transfer effect. The excellent performance of the hydrate formation kinetics gives us strong confidence in the reliability and accuracy of the new model. This provides reliable predictions and mechanistic understandings of hydrate formation kinetics in the porous media.

Modeling of hydrate formation prediction in binary components of natural gas

Temperature is calculated as a function of gas gravity and pressure using an exponential function with two constant parameters, a and b. To obtain the best prediction model of gas hydrate formation, the behavior of these parameters in response to changes in gas gravity is monitored . Methane-ethane, methane-propane, ethane-propane, and ethane-carbon dioxide are among the binary components to which the suggested model is applied. The suggested predictive model outperforms the existing correlation approaches, such as Hammerschmidt, Motiee, and Ghiasi correlations, according to statistical analysis. The type of gases that make up the hydrate has a big impact on the gas hydrate equilibrium line, and the predictive model's constant values are different for each binary component. As a result, this study indicates that rather than constructing an empirical correlation-based on the assumption that the specific gas gravity is a general characteristic independent of the kind of gas hydrate mixture, a predictive model should be established for each gas hydrate mixture.

Experimental Simulation of Hydrate Formation Process in a Circulating Device

This paper focuses on the model of gas hydrate formation in an experimental device, which allows the circulation of the resulting mixture (water and gas) and significantly accelerates the process of hydrate formation in the laboratory. A 3D model was developed to better imagine the placement of individual parts of the device. The kinetics of hydrate formation were predicted from equilibrium values of chemical potentials. The aim of solving the equations of state gases in the mathematical model was to optimize the parameters involved in the formation of hydrates. The prediction of the mathematical model was verified by numerical simulation. The mathematical model and numerical simulation predict the chemical reaction evolving over time and determine the amount of crystallized water in the reactor. A remarkable finding is that the deviation of the model and simulation at the initiation the calculation of crystallized water starts at 76% and decreases over time to 2%. Subsequently, the number of moles of bound gas in the hydrate acquires the same percentage deviations. The amount of water supplied to the reactor is expressed by both methods identically with a maximum deviation of 0.10%. The different character is shown by the number of moles of gas remaining in the reactor. At the beginning of the calculation, the deviation of both methods is 0%, but over time the deviation slowly increases, and at the end it expresses the number of moles in the reactor with a deviation of 0.14%. By previous detection, we can confirm that the model successfully determines the amount of methane hydrate formed in the reactor of the experimental equipment. With the attached pictures from the realized experiment, we confirmed that the proposed method of hydrate production is tested and takes minutes. The article calculates the energy efficiency of natural gas hydrate in the proposed experimental device.

Numerical Modeling of Gas Hydrate Formation in a Porous Collector

Numerical Modeling of Gas Hydrate Formation in a Porous Collector

Simplified diffusion model of gas hydrate formation from ice

A kinetic model of gas hydrate formation from ice is presented. This model takes into account that the kinetics of gas hydrate formation from ice is limited only by the rate of diffusion of the gas through the gas hydrate layer. The problems of gas hydrate formation from a spherical ice particle, gas hydrate formation from a flat ice layer, and gas hydrate formation from cylindrical ice are considered separately. For each of these problems, a solution in the framework of a quasi-stationary approximation is obtained. The calculated data are compared with available experimental data on the kinetics of formation of methane hydrate and carbon dioxide hydrate from ice powder. From this comparison, the temperature dependence of the molecular diffusion coefficient of methane in methane hydrate and the temperature dependence of the molecular diffusion coefficient of carbon dioxide in carbon dioxide hydrate were determined: DCH4[m2s−1]=exp(−12.8−6242/T[K]) and DCO2[m2s−1]=exp(−30.0−1179/T[K]). In addition, from this comparison, it was found that the porous structure is absent in the volume of gas hydrate formed from ice. Taking into account the determined temperature dependence of the molecular diffusion coefficient of methane in methane hydrate, it is found that methane hydrate formation from ice proceeds more intensively the closer the temperature is to the quadruple point temperature and the higher the methane pressure is.

Mathematical model of gas hydrate formation of sulfur dioxide by injecting liquid sulfur dioxide into a layer saturated with methane and water

This paper presents the results of a theoretical study for the gas hydrate formation of sulfur dioxide by injecting liquid sulfur dioxide into a layer saturated with water and methane. Self-similar solutions of a straight-line parallel problem are constructed. The dependences of the temperature and the coordinates of the formation front of sulfur dioxide gas hydrate on the layer permeability are explored. It is established that, as the layer permeability increases, the temperature of the phase transition increases on the surface. As a result, at sufficiently large values of layer permeability, the temperature at the hydrate formation border may exceed the equilibrium decomposition temperature of sulfur dioxide gas hydrate, which will correspond to the appearance of an intermediate region saturated with a mixture of water, sulfur dioxide and its gas hydrate in a state of thermodynamic equilibrium. It is established that at sufficiently high values of injection pressure and permeability, the gas hydrate formation of sulfur dioxide will occur in the extended region.

Multiphase Flow Law and Well Control Risk Analysis in Deep Water Gas Hydrate Horizontal Well While Drilling

Natural gas hydrate is an important clean energy in the future because of its high energy density, clean and pollution-free, large amount of resources and wide distribution. However, the gas hydrate reservoir in the sea area has the characteristics of deep water depth and shallow reservoir buried depth. It is difficult to develop, and the development cost is high, so it is difficult to meet the needs of commercial exploitation. Horizontal well drilling can ensure reservoir drilling rate, increase reservoir drainage area and improve development efficiency. During the drilling process of deep water gas hydrate horizontal wells, the gas hydrate is decomposed into gaseous gas due to the change of temperature and pressure environment. The multiphase transient flow of gas in the wellbore will affect the wellbore temperature and pressure environment and cause well control risk. The calculation model of multiphase transient flow and temperature field in drilling wellbore of deepwater gas hydrate horizontal well and the model of gas hydrate formation were established. The gas distribution, migration law and temperature and pressure distribution in wellbore were analyzed, and the variation of wellbore pressure, surface flow law and temperature and pressure range of gas hydrate formation were grasped, which will provide theoretical basis and construction reference for deep water gas hydrate horizontal well drilling.

Modeling of Gas Hydrate Formation Upon Injection of Carbon Dioxide Gas into A Natural Reservoir

This paper presents the results of numerical modeling of gas hydrate formation upon injection of carbon dioxide into a finite-length reservoir saturated with methane and water. It is shown that at different stages, hydrate formation can occur on both the frontal surface and in a reservoir region of finite length. The effects of pressure at the reservoir boundaries and the effects of the permeability and initial water saturation of the reservoir on the hydrate formation process were studied. The dependences of the time of the complete conversion of water into gas hydrate in the entire reservoir on the injection pressure and reservoir permeability were obtained.

Modeling of Gas Hydrate Formation upon Injection of Carbon Oxide Gas into a Natural Reservoir

Modeling of Gas Hydrate Formation upon Injection of Carbon Oxide Gas into a Natural Reservoir

PREDICTION OF THE METHANE SUPPLY AND FORMATION PROCESS OF GAS HYDRATE RESERVOIR AT ODP1247, HYDRATE RIDGE, OFFSHORE OREGON

AbstractThe formation of gas hydrate reservoir in marine sediments is mainly controlled by methane supply and sedimentary burial. Based on the mass conservation of methane in gas hydrate system, a numerical model of gas hydrate formation was established considering the methane supplied by dissolved methane diffusion, pore water advection, and in situ methanogenesis. A case study of ODP site 1247 at the Hydrate Ridge, offshore Oregon shows that dissolved methane transported by molecular diffusion and pore water advection is the major supply of methane for gas hydrate formation, while in situ methanogenesis contributes little to the gas hydrate reservoir. The gas hydrate reservoir was also evaluated considering the changes of sedimentation rate since 1.67 Ma. Our model results show that the variations of sedimentation rate lead to little change in the size of gas hydrate reservoir at ODP 1247. The calculated hydrate saturation amounts to ∼0%∼3%, which is consistent with the measured values using pressure coring.

Migration of a single gas bubble in water during the formation of stable gas-hydrate crust on its surface

A theoretical model of gas-hydrate formation during the migration of the methane bubble in water under thermobaric conditions of hydrate stability has been considered. Numeric solutions were obtained and analyzed for two limiting cases when the rate of formation of the hydrate crust on bubble surface is constrained by the intensity of heat removal, which is released during hydrate-formation process by the surrounding water or the diffusive resistance of gas hydrate crust against the transfer of hydrate-forming components. A comparative analysis of the numeric results with the experimental data showed that the diffusive transfer of hydrate-forming components through the crust most adequately described the process of hydrate-particle growth that was observed in experiments during the ascent of methane particles in seawater. The conditions of the best agreement between the theoretical and experimental data on changing of radius of gas-hydrate particle allowed numeric estimates to be obtained for values of the reduced coefficient of gas and water diffusion through the hydrate crust.

Thermodynamic modeling of gas hydrate formation in presence of thermodynamic inhibitors with a new association equation of state

Formation of hydrate crystal particles has been one of the major difficulties facing gas industry in the generation, transmission, and processing that causes blockage of pipelines and equipment resulting in decreases of level of safety and immunity Which necessitating proper methods to prevent hydrate formation. One of the most common treatments are injection of chemical inhibitors. Keeping excessive cost of hydrate remediation and inhibition in mind, using a reliable predictive model is the key step of designing a natural gas transmission operation.In this paper the van der Waals and Platteeuw (vdW-P) model was coupled with Dehaghani et al.'s association equation of state (DA-EOS) for prediction of equilibrium temperature of methane hydrate in presence of methanol (MeOH), ethanol (EtOH), and mono-ethylene glycol (MEG) as thermodynamic inhibitors. To increase the calculation accuracy, the mole fraction of components in the liquid and gas phases were obtained using the results of flash algorithm calculations. In addition, effect of gas dissolution in aqueous phase was considered by Henry's law and water activity coefficient calculation was performed based on φ- φ approach. Additionally, the binary components interaction coefficients in the system, was considered as a linear function of temperature.To evaluate the capability of DA-EOS, the prediction of methane hydrate phase behavior in presence and absence of inhibitors was compared with the experimental data and also the prediction of Peng-Robinson EOS (PR-EOS). In addition, a comparison was made between DA-EOS and Elliott–Suresh–Donohue uation of State (ESD-EOS) to gain insight of performance of present model. The prediction of DA-EOS and ESD-EOS was close to each other. DA-EOS proved to be effective in representing self-association between water and cross-association between water-inhibitor components in the case of hydrate solution. Also, it was concluded that performance of vdW-P model strongly depends on reliability of EOS used for calculation of fugacity coefficient.

Modeling of Gas Hydrate Formation in the Presence of Inhibitors by Intelligent Systems

Gas hydrate formation in production and transmission pipelines and consequent plugging of these lines have been a major flow-assurance concern of the oil and gas industry for the last 75 years. Gas hydrate formation rate is one of the most important topics related to the kinetics of the process of gas hydrate crystallization. The main purpose of this study is investigating phenomenon of gas hydrate formation with the Presence of kinetic Inhibitors in operation gas transmission, and prediction of gas hydrate formation rate in the pipeline. In this regard, by using experimental data and Intelligent Systems (Artificial neural networks and adaptive neural-fuzzy system), two different high efficient and accurate models were designed to predict hydrate formation rate of CO2, C1, C3, and i-C4. It was found that such models can be used as powerful tools, for prediction of gas hydrate formation rate with total average of absolute deviation less than 6%.

Diffusion model of gas hydrate formation from ice

Assuming that gas hydrate formation from ice occurs through a diffusion mechanism, a system of equations was developed that describes the kinetics of gas hydrate formation from a spherical ice particle. This model takes into account the porous structure of the formed gas hydrate as well as the increases in particle volume due to the formation of the gas hydrate. In addition, the intrinsic kinetics of gas hydrate formation from ice is considered. In the framework of a quasi-stationary approximation, a simplified solution for the system of equations was obtained. From the comparison between the calculated and available experimental data, the temperature dependence was determined for the diffusion coefficient of methane in methane hydrate.

Experimental and Modeling Studies on the Prediction of Gas Hydrate Formation

On the base of some kinetics model analysis and kinetic observation of hydrate formation process, a new prediction model of gas hydrate formation is proposed. The analysis of the present model shows that the formation of gas hydrate not only relevant with gas composition and free water content but also relevant with temperature and pressure. Through contrast experiment, the predicted result of the new prediction method of gas hydrate crystallization kinetics is close to measured result, it means that the prediction method can reflect the hydrate crystallization accurately.

Application of artificial intelligence (AI) in kinetic modeling of methane gas hydrate formation

This paper aims to present a kinetic study of formation of methane gas hydrate (GH) using artificial intelligence (AI) tools. Generally, study of the kinetics of GH formation will help to better understand this process in order to control it favorably. However, due to its complexity, this process is not fully understood yet. More studies in the literature are considering the thermodynamics of gas hydrate formation both experimentally and mathematically. However, there is no sufficient studies regarding the kinetics of gas hydrates and most of the experimental data and specifically the kinetic models in the literature are incomplete. That may be due to inherent stochastic behavior of GHs which makes it difficult to develop a deterministic model for it. Nowadays, Artificial Intelligence (AI) methods including Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) have been proved as a novel and potential tools with acceptable accuracy for modeling of engineering systems. Therefore, this paper aims to investigate the kinetics of gas hydrate formation using ANN and ANFIS when the relation between growth rate of methane hydrate, temperature and pressure has been modeled. Moreover, this can also be achieved using complicated governing equations but AI provides a less complex and easier way to accomplish this goal. Experimental data considering the methane hydrate growth rate as a function of pressure and temperature were used and ANFIS as well as ANN were employed to duplicate them. In this study, the results reveal that ANIFS could better predict the methane hydrate growth rate in the prevailing pressure and temperature conditions compared to ANN. Generally this study shows the effectiveness of AI based techniques for kinetics modeling of gas hydrates formation.

Experimental study and kinetics modeling of gas hydrate formation of methane–ethane mixture

Abstract. In this study, gas hydrate formation kinetics of methane and ethane binary mixtures has been studied and data of mixed methane–ethane hydrate formation at 0.1, 0.2, 0.3, 0.5, 0.68, 0.8, and 0.9 mole fractions of methane and at a temperature of 277.15 K and an initial pressure of approximately 3.6 MPa were collected. The thermodynamic natural path was used for modeling the hydrate formation rate in a constant volume process. The results show that there is good agreement between model prediction and experimental data, with an average error of 0.9%. It was observed that the values of these parameters are dependent on the concentration of components in the mixtures. The results indicate that this model can predict constant volume experimental data of binary mixture hydrate.

Stoichiometric Approach toward Modeling the Decomposition Kinetics of Gas Hydrates Formed from Mixed Gases

Following a recent study by Giraldo et al. (Giraldo, C.; Maini, B.; Bishnoi, P. R. A simplified approach to modeling the rate of formation of gas hydrates formed from mixtures of gases. Energy Fuels 2013, 27, 1204−1211), in which a new stoichiometry-based approach was taken to model the rate of gas hydrate formation for mixed gases, a new stoichiometric approach has been proposed to describe the kinetics of gas hydrate decomposition from mixed gases. Similar to the model of gas hydrate formation by Giraldo et al., the newly proposed model of gas hydrate decomposition has the advantage that the intrinsic rate constant of gas hydrate decomposition is only required for a single component. To test the model, gas hydrate decomposition experiments were conducted in a semi-batch stirred-tank reactor, equipped with an in situ particle size analyzer, to study the rate of decomposition of gas hydrates formed from mixtures of carbon dioxide and methane. Two gas mixtures of CO2 (1) + CH4 (2), one with x1 = 0.4 and th...

Mathematical model of hydrate formation from microbial methane in marine sediments

A mathematical model of gas hydrate formation from microbial methane in marine sediments is proposed. An analytical solution of the problem is obtained, determining dimensionless parameters are distinguished, and numerical investigation is performed. In the region of main parameters a critical diagram of hydrate existence is plotted. It is shown that at small sediment accumulation rates microbial methane disperses due to diffusion of dissolved gas which does not reach saturation. If the sediment accumulation is intense, the region of possible hydrate formation falls within the region of stable thermodynamic states only at large depths. Correspondingly, in these cases, the probability of formation of hydrate-containing sediment layers is small. The most probable hydrate formation regime is realized at moderate sediment accumulation rates corresponding to Peclet numbers of the order of unity.