Gas Hydrate Formation Conditions Research Articles

CH4 Adsorption in Wet Metal-Organic Frameworks under Gas Hydrate Formation Conditions Using A Large Reactor

Nanoporous materials, such as metal-organic frameworks (MOFs), are renowned for their high selectivity as gas adsorbents due to their specific surface area, nanoporosity, and active surface chemistry. A significant challenge for their widespread application is reduced gas uptake in wet conditions, attributed to competitive adsorption between gas and water. Recent studies of gas adsorption in wet materials have typically used small amounts of powdered porous materials (in the milligram range) within very small reactors (1–5 mL). This leaves a gap in knowledge about gas adsorption behaviors in larger reactors and with increased MOF sample sizes (to the gram scale). Additionally, there has been a notable absence of experimental research on MOFs heavily saturated with water. In this study, we aimed to fill the gaps in our understanding of gas adsorption in wet conditions by measuring CH4 adsorption in MOFs. To do this, we used larger MOF samples (in grams) and a large-volume reactor. Our selection of commercially available MOFs, including HKUST-1, ZIF-8, MOF-303, and activated carbon, was based on their widespread application, available previous research, and differences in hydrophobicity. Using a volumetric approach, we measured high-pressure isotherms (at T = 274.15 K) to compare the moles of gas adsorbed under both dry and wet conditions across different MOFs and weights. The experimental results indicate that water decreases total CH4 adsorption in MOFs, with a more pronounced decrease in hydrophilic MOFs compared to hydrophobic ones at lower pressures. However, hydrophilic MOFs exhibited stepped isotherms at higher pressures, suggesting water converts to hydrate, positively impacting total gas uptake. In contrast, the hydrophobic ZIF-8 did not promote hydrate formation due to particle aggregation in the presence of water, leading to a loss of surface area and surface charge. This study highlights the additional challenges associated with hydrate-MOF synergy when experiments are scaled up and larger sample sizes are used. Future studies should consider using monolith or pellet forms of MOFs to address the limitations of powdered MOFs in scale-up studies.

EXPERIMENTAL STUDY OF HYDRATE FORMATION PECULIARITIES FOR CONDITIONS OF THE TURNO AND CENOMANIAN DEPOSITS. Part I

This paper is the Part I of a study devoted to investigating the peculiarities of hydrate formation for the conditions of Turonian and Cenomanian reservoirs. The launch of new gas projects at the Turon and Senoman production facilities in Western Siberia provided a good opportunity to critically analyze the known methods of protecting production, gathering and transportation facilities of the gas field from the formation of solid gas hydrates. The paper presents the experience of implementing a program of laboratory studies of conditions of gas hydrate formation with their subsequent processing and in-depth analysis. The research program covered the area of thermobaric parameters typical for the conditions of Turon-Senoman deposits exploitation with localization of hydrate-hazardous areas in the conditions of technological regimes for full development. The description of laboratory studies is given, in which two gas compositions of Senoman and Turon objects, different variants of mineralization and ionic composition corresponding to formation and condensation water, as well as hydrate formation conditions under changing dosages of basic inhibitor on the basis of methanol were considered. The details of the experiment based on the method of swinging cells and the subsequent analysis of the results of the completed experiments to determine the thermobaric conditions of formation and decomposition of hydrates are given. The main features of the experiment are specified, estimates of the rate of change of the influencing parameters of the experiment on its quality are given. In the process of implementation of the experimental program, the optimal values of these parameters were selected, which allowed us to significantly reduce the variation of experimental results to determine the thermobaric conditions of hydrate formation. It is experimentally established that the temperature of hydrate decomposition is higher than the temperature of its formation at all investigated gas compositions and water mineralization.Based on the processing of an extensive matrix of experimental studies, the calculation dependences of thermobaric conditions of hydrate formation were specified, which allowed to significantly improve the efficiency of prediction and accuracy of calculation of optimal dosages of inhibitor for the Kharampurskoye gas field. In this part of the study, the characteristic thermobaric conditions of natural gas production and collection from Turonian-Cenomanian deposits are summarized, the component composition of the investigated gas and water is described, and the methodology of laboratory tests is described.

Analytical Prediction of Gas Hydrate Formation Conditions for Oil and Gas Pipeline

Analytical Prediction of Gas Hydrate Formation Conditions for Oil and Gas Pipeline

Prediction of Phase Equilibrium Conditions and Thermodynamic Stability of CO2-CH4 Gas Hydrate

With the large-scale promotion and application of CO2 flooding, more and more engineering problems have emerged. Due to the high CO2 mole fraction, the associated gas of CO2 flooding very easily forms solid hydrates, compared to conventional natural gas. This has resulted in production decline or shutdown. Understanding the phase equilibrium conditions for hydrate formation in production fluids is crucial for hydrate prevention and control. In this study, accurate predictions of CO2-CH4 mixed gas hydrate formation conditions were performed using theoretical models. The temperature and pressure ranges for hydrate formation were calculated for different CO2 mole fraction, ranging from −11.5 °C to 20.85 °C and from 0.81 MPa to −28.1 MPa, respectively. Based on the calculated phase equilibrium data, a multi-parameter empirical model was developed using polynomial fitting. The calculation errors for the multi-parameter empirical model were 3.09%. The multi-parameter empirical model established in this study can avoid complex thermodynamic equilibrium calculations and has the advantages of simplicity, high accuracy, and wide coverage of downhole conditions. Based on the calculated phase equilibrium data, the dissociation enthalpy of CO2-CH4 hydrate below and above the freezing point of water was calculated. The results showed that an increase in CO2 mole fraction led to an increase in hydrate dissociation enthalpy and enhanced thermodynamic stability, making hydrate prevention more challenging. Our work can contribute to the optimization of CO2 production fluid treatment processes and the development of hydrate prevention and control technologies.

Research on Wellbore Stability in Deepwater Hydrate-Bearing Formations during Drilling

Marine gas hydrate formations are characterized by considerable water depth, shallow subsea burial, loose strata, and low formation temperatures. Drilling in such formations is highly susceptible to hydrate dissociation, leading to gas invasion, wellbore instability, reservoir subsidence, and sand production, posing significant safety challenges. While previous studies have extensively explored multiphase flow dynamics between the formation and the wellbore during conventional oil and gas drilling, a clear understanding of wellbore stability under the unique conditions of gas hydrate formation drilling remains elusive. Considering the effect of gas hydrate decomposition on formation and reservoir frame deformation, a multi-field coupled mathematical model of seepage, heat transfer, phase transformation, and deformation of near-wellbore gas hydrate formation during drilling is established in this paper. Based on the well logging data of gas hydrate formation at SH2 station in the Shenhu Sea area, the finite element method is used to simulate the drilling conditions of 0.1 MPa differential pressure underbalance drilling with a borehole opening for 36 h. The study results demonstrate a significant tendency for wellbore instability during the drilling process in natural gas hydrate formations, largely due to the decomposition of hydrates. Failure along the minimum principal stress direction in the wellbore wall begins to manifest at around 24.55 h. This is accompanied by an increased displacement velocity of the wellbore wall towards the well axis in the maximum principal stress direction. By 28.07 h, plastic failure is observed around the entire circumference of the well, leading to wellbore collapse at 34.57 h. Throughout this process, the hydrate decomposition extends approximately 0.55 m, predominantly driven by temperature propagation. When hydrate decomposition is taken into account, the maximum equivalent plastic strain in the wellbore wall is found to increase by a factor of 2.1 compared to scenarios where it is not considered. These findings provide crucial insights for enhancing the safety of drilling operations in hydrate-bearing formations.

Gas production behaviour of gas hydrate–bearing clayey-sand during depressurization: novel in-flight centrifuge modelling

Gas hydrate-bearing sediments (GHBS) are vastly distributed around the globe. While gas production attempts are made through GHBS, long-term production remains a challenge due to complex inter-related mechanisms involved. Better understating of long-term responses requires sound physical modelling conducted under controlled conditions. A novel centrifuge energy harvesting chamber (CEHC) at the HKUST centrifuge facility is used in this study. This is the first chamber that can operate at elevated gravities with the capability of sustaining the thermodynamically favourable conditions for gas hydrate formation, sustaining a continuous inflow of high-pressure water at the boundaries during dissociation, and an in-flight control of wellbore pressure and surcharge loading. Centrifuge modelling can recreate the insitu stress gradient in a relatively small model and expedite conduction and convection processes involved during dissociation. Consequently, long-term in-situ mechanisms can be evaluated with a small model and short time. A test was conducted at 40g to evaluate the temperature-pressure response as well as gas production behaviour of hydrate-bearing clayey-sand during depressurization. The results suggests that the gas flow rate is governed by the initial available latent heat as well as the conduction and convection heat through the surrounding sediments. However, as the depressurization progresses, the gas production rate is governed by the competing effects of hydrate dissociation and re-formation which both evolves the permeability of the sediment. Details of the experiment and test results are reported in this paper.

Experimental investigation on the phase behaviour for gas hydrates in CO2 rich gas mixtures & multiphase system

Almost 40% of undiscovered hydrocarbon reserves have high CO2 and H2S concentrations around the globe. So it is crucial to understand these hydrocarbon systems’ thermophysical properties for the excellent design of production facilities. An experimental investigation is conducted in this study to understand and evaluate the thermodynamic conditions of gas hydrate formation in natural gas systems with high CO2 levels gas and dominant multiphase (high CO2 level gases, deionized water, and crude oil). Three gas mixtures were chosen in this study to simulate natural gas with high CO2 content. The experiments are conducted within the critical pressure of the selected gas to avoid any phase change due to pressure. The impact of high CO2 levels in gas systems on the thermodynamic conditions of the gas hydrates was first explored. Then, the effect of a multiphase system was investigated after the addition of the oil phase into the system. The thermodynamic equilibrium conditions obtained from experiments were used to construct the Hydrate liquid–vapour Equilibrium (HLVE) curves, and the phase behaviour was studied. The details about the temperature variance and enthalpy are also clearly discussed. It has been discovered that gas mixtures with a higher CO2 content tend to promote compared to the pure methane gas system but inhibit compared the pure CO2 system. But in the multiphase system, all the gases show an inhibition effect compared to their respective pure gas system results.

Extension of the electrolyte Trebble–Bishnoi EOS to mixed‐salt systems, and application to vapour liquid and solid (hydrate) vapour liquid equilibrium calculations

AbstractThis work examines the use of the electrolyte Trebble–Bishnoi equation of state (eTBEOS) in predicting high‐pressure phase equilibria in the presence of aqueous mixed‐salt solutions. The eTBEOS combines the Trebble–Bishnoi equation of state with a Born energy term, a mean spherical approximation term, and a cation solvation term. Shortcomings in the originally regressed set of eTBEOS parameters are identified and discussed, and a new set of equation of state parameters is subsequently regressed for 58 salts. In order to extend the eTBEOS to mixed‐salt systems, two approaches for computing the EOS parameters of the ionic species are investigated. The first approach uses the originally regressed parameter set plus parameter mixing rules, where appropriate, whereas the second approach uses the newly regressed parameters and no mixing rules. In the prediction of osmotic coefficients in mixed‐salt solutions, the maximum relative difference between the experimental and computed values was 5.70%. For the gas solubility predictions, data were available for the solubility of CO2, CH4, and N2 in a small number of mixed electrolyte solutions; the maximum relative difference was 5.79%. Finally, CH4, C2H6, C3H8, and CO2 gas hydrate formation conditions were predicted in a number of mixed‐salt solutions, with a maximum relative difference of 10.76%. Overall, it was seen that both approaches allowed for comparable accuracy in phase equilibrium calculations. However, in the case of solutions made from salt mixtures with common cations, the second approach consistently resulted in improved accuracy.

Equilibrium conditions of CO2+C3H8 hydrates in pure and saline water solutions of NaCl

Gas hydrate formation and dissociation have been extensively studied in past decades after introducing hydrate-based technology in the energy and environmental fields. Among all, hydrate-based water desalination (HBWD) has been receiving significant attention because of the shortage in water resources. The present study investigates the equilibrium conditions for gas hydrate formation from propane and carbon dioxide gas mixtures in the presence of pure water and low saline aqueous solutions for the first time. According to the carried out sensitivity analysis on thermodynamic equilibrium conditions of the CO2+C3H8 mixture with different mole fractions of propane (5–50% C3H8 + balanced CO2) it was concluded that the addition of propane above 20% did not significantly affect the hydrate equilibrium condition. Experiments have been carried out with an initial gas molar composition of 20% C3H8 and 80% CO2 in a temperature range of 275.15–280.15 K, at isochoric conditions for the first time. The inhibition effect on the equilibrium conditions is reported in the case of NaCl addition (1, 1.5, 2, and 3 wt%). A reasonable agreement between the experimental data and those calculated from the thermodynamic model applied in this study has been obtained. According to the tests results, the coefficient of determination (R squared) of the final results of the conducted tests and the model predictions are 0.9987 and 0.9950 for pure and saline water, respectively.

Twin Support Vector Regression for Prediction of Natural Gas Hydrate Formation Conditions

Natural gas hydrates have become a threat to natural gas companies and oil industries for the formation of gas hydrates in transfer pipelines can lead to pipe blockage. Natural gas hydrate formation is favored by low temperature and high pressure; thus, if the right combination of temperature and pressure are well investigated, it is possible to solve the pipe blockage problems. Therefore, developing a precise, easy-to-use method to predict natural gas hydrate formation temperature (HFT) is very important. In this paper, we are intended to develop a novel machine learning model called twin support vector regression (TSVR) for predicting HFT in a wide range of natural gas mixtures. For constructing the TSVR model, 513 experimental data in the system methane, ethane, propane, butane, pentane, nitrogen, carbon dioxide/water, methane, carbon dioxide, propane, methanol, sodium chloride, and calcium chloride have been collected from open literature. We compared the performance of the TSVR model with least squares support vector regression (LSSVR) and three widely used correlations in the system methane, ethane, propane, butane, pentane, nitrogen, and carbon dioxide, which show that the TSVR model has fewer deviations than the LSSVR model and three correlations. The values of root-mean-square error (RMSE), mean absolute percentage error (MAPE), and correlation factor (R2) are 2.4010, 0.0061, and 0.9108, respectively. In addition, statistical parameters show that the TSVR model can also surpass the LSSVR model in predicting HFT in the system water, methane, carbon dioxide, propane, methanol, sodium chloride, and calcium chloride.

New «green» inhibitors of gas hydrate formation for the oil and gas industry based on polysaccharides

The thermobaric conditions for the formation of gas hydrates in the presence of the sodium salt of carboxymethylcellulose, dextran, and arabinogalactan were studied in a quasi-equilibrium thermodynamic experiment. It is established that polysaccharides slow down the rate and change the conditions of gas hydrate formation of a mixture of natural gases, showing the properties of a thermodynamic and kinetic inhibitor with technological efficiency exceeding methanol by 170-270 times when used in the same dosages. The results of the development of a «green» synergistic inhibitor of gas hydrate formation «Glycan RU» on their basis are presented, which includes a combination of thermodynamic and kinetic inhibitors. Pilot field tests of «Glycan RU» were carried out at the wells of the Priobskoye, Prirazlomnoye, Ombinsky, Zapadno-Ugutskoye oilfields. It was found that at dosages of 1000 g/m3 and 500 g/m3, there is no formation of hydrate plugs in the annulus. «Glycan RU» is recommended for industrial use by the technology of periodic injection and/or continuous dosing through wellhead dispensers. Keywords: carboxymethylcellulose; dextran; arabinogalactan; polysaccharides; «green» inhibitor of gas hydrate formation; «Glycan RU».

Characterization of the coupling between gas hydrate formation and multiphase flow conditions

Gas hydrates can readily form in deep-water oil and gas production processes and can lead to disruptions in flow conditions. In this work, in order to investigate the interdependence of hydrate formation and multiphase flow characteristics, a transparent rock-flow cell was used where a series of hydrate formation and flow experiments were conducted under different rocking conditions, which corresponded to different flow regimes. Based on the experimental phenomena, stratified gas-liquid flow pattern, two kinds of emulsions, and three kinds of liquid-liquid flow patterns were identified under different rocking conditions before hydrate formation. Upon hydrate formation onset, phase separation of the liquid phases could be only clearly observed for W/O emulsions. In this work, hydrates mainly formed in the bulk liquid and gradually deposited on the pipe wall by particle-wall adhesion and accumulated on the two ends of the pipe under flow conditions. In addition, for small rocking angles, hydrate chunks formed by agglomeration and hydrate bedding at the bottom of the pipe could be observed. For all the experiments, no free water could be observed at the end of the test. Moreover, the water conversion for each rocking condition was calculated according to the gas consumption. This work provides further insight how flow conditions affect hydrate formation and vice-versa.

Integrating Support Vector Regression with Genetic Algorithm for Hydrate Formation Condition Prediction

To predict the natural gas hydrate formation conditions quickly and accurately, a novel hybrid genetic algorithm–support vector machine (GA-SVM) model was developed. The input variables of the model are the relative molecular weight of the natural gas (M) and the hydrate formation pressure (P). The output variable is the hydrate formation temperature (T). Among 10 gas samples, 457 of 688 data points were used for training to identify the optimal support vector machine (SVM) model structure. The remaining 231 data points were used to evaluate the generalisation capability of the best trained SVM model. Comparisons with nine other models and analysis of the outlier detection revealed that the GA-SVM model had the smallest average absolute relative deviation (0.04%). Additionally, the proposed GA-SVM model had the smallest amount of outlier data and the best stability in predicting the gas hydrate formation conditions in the gas relative molecular weight range of 15.64–28.97 g/mol and the natural gas pressure range of 367.65–33,948.90 kPa. The present study provides a new approach for accurately predicting the gas hydrate formation conditions.

Prediction of Gas Hydrate Formation Conditions in the Presence of Electrolytes Using an N-NRTL-NRF Activity Coefficient Model

The presence of electrolytes will decrease the hydrate formation temperature at a given pressure. And the reduction of formation temperature is closely related to the type and salinity of electroly...

Relative Pressure Drop Model for Hydrate Formation and Transportability in Flowlines in High Water Cut Systems

Today, oil and gas fields gradually become mature with a high amount of water being produced (water cut (WC)), favoring conditions for gas hydrate formation up to the blockage of pipelines. The pressure drop is an important parameter which is closely related to the multiphase flow characteristics, risk of plugging and security of flowlines. This study developed a model based on flowloop experiments to predict the relative pressure drop in pipelines once hydrate is formed in high water cutsystems in the absence and presence of AA-LDHI and/or salt. In this model, the relative pressure drop during flow is a function of hydrate volume and hydrate agglomerate structure, represented by the volume fraction factor (Kv). This parameter is adjusted for each experiment between 1.00 and 2.74. The structure of the hydrate agglomerates can be predicted from the measured relative pressure drop as well as their impact on the flow, especially in case of a homogeneous suspension of hydrates in the flow.

Дослідження термодинамічних умов формування гідратів генераторного газу

The paper considers the problems that have arisen during the implementation of underground coal gasification technology at coal deposits development of coal fields, with the transportation of the generator gas. The future direction of gas transportation in the form of gas hydrates which reduce the system of industrial and main gas pipelines is proposed. The Clausius-Clapeyron equation has been improved for analytical studies of gas hydrate formation conditions, taking into account the presence of nonequilibrium defects in phase 1 (ice + gas → solid phase), which is converted to phase 2 (water + gas → liquid phase). In this case, this equation is supplemented by considering the thermal effect of the transformations phase (thermal effect of defect relaxation). Significant increase of internal energy in the initial phase before transformations gas hydrate state is the accumulation in it of the limit concentrations of various defects and voids. Obtaining non-equilibrium structures in the initial materials due to the accumulation of various non-equilibrium voids in them, which are associated with an increase in the heat transfer rate, is one of the directions of the process activation during phase changes. It has been determined that the relaxation energy of defect is a thermodynamic stimulus for controllable phase transformations and solid-phase reactions. Simultaneous rapid heating and pressure increase are required to simultaneously reduce the temperature and pressure.

Prediction of natural gas hydrates formation using a combination of thermodynamic and neural network modeling

During the treatment or transport of natural gas, the presence of water, even in very small quantities, can trigger hydrates formation that causes plugging of gas lines and cryogenic exchangers and even irreversible damages to expansion valves, turbo expanders and other key equipment. Hence, the need for a timely control and monitoring of gas hydrate formation conditions is crucial.This work presents a two-legged approach that combines thermodynamics and artificial neural network modeling to enhance the accuracy with which hydrates formation conditions are predicted particularly for gas mixture systems. For the latter, Van der Waals-Platteeuw thermodynamic model proves very inaccurate. To improve the accuracy of its predictions, an additional corrective term has been approximated using a trained network of artificial neurons. The validation of this approach using a database of 4660 data points shows a significant decrease in the overall relative error on the pressure from around 23.75%–3.15%. The approach can be extended for more complicated systems and for the prediction of other thermodynamics properties related to the formation of hydrates.

Prediction of Methane and Ethane Gas Hydrate Formation and Their Mixture in a Porous Medium

The purpose of this paper is to study the thermodynamic modeling of the conditions for methane and ethane gas hydrate formation and their mixtures in a porous and non-porous environment. In this paper, the Van der Waals- Platteeuw thermodynamic model was used for prediction of gas hydrate formation conditions. Also, the SRK and PTV equations of state were used for calculations of driving force. In this research, the results of thermodynamic modeling in a porous were compared with the non-porous environment and laboratory data in the literature. Studies have shown that the results of the modeling are in good agreement with the laboratory data and the percentage of errors is low. The results also showed that with increasing pressure of porous and non-porous media, the equilibrium temperature increases. In addition, the effect of the pore diameter of porous media on the results of modeling was investigated for methane, ethane and their mixtures during gas hydrates formation. The results showed that by increasing the pressure for any size of the pore diameter of the porous medium, hydrate formation temperature increases. In addition, by increasing the pore diameter of the porous medium, hydrate formation temperature methane, ethane and their mixture increase at a constant pressure. The results also showed that the equilibrium temperature of the non-porous medium is higher than the equilibrium temperature of the non-porous medium. This shows that the hydrate formation in the porous medium has a deterrent effect and leads to lower temperatures and higher temperatures conditions for gas hydrate formation. The results showed that by increasing the percentage of methane in a porous or non-porous medium, the temperature of hydrate formation of the binary gas mixture of methane and ethane decreases.

Predicting the conditions for gas hydrate formation

ABSTRACTGas hydrate is a crystalline mixture obtained from gas molecules trapped in the cavity of hydrogen bonding water. To date, an essential step in the development of natural gas industry has been the acquisition of knowledge in the operation and handling of gas under high pressure without hydrate formation. Since there are several ways to predict hydrate formation, this study investigates predicting hydrate formation using the Katz method. In addition, several new models for accurate estimation of gas hydrate formation conditions will be provided. These models are based on artificial neural network (ANN) requirements. To create the model, predictive experimental data published in books and journals, as well as data extracted from Katz graph (Katz chart), estimate the formation conditions of gas hydrate. We validate the model created with the use of various statistical parameters such as mean squared error (MSE) and R2-value. The result of these parameters in models created to predict the formation of hydrates accurately and efficiently is evaluated. In this study, our goals are to use an artificial intelligence neural network to predict the formation of gas hydrates.

Carboxymethylcellulose sodium salt – effective “green” regent for management of calcium carbonate crystallization and nat-ural gas hydrate formation

The effect of carboxymethylcellulose sodium salt (NaCMC) with molecular masses (Mw) of 90, 250 and 700 thousand on the crystallization of CaCO3 polymorphs, their size and deposition on the surface of stainless steel from supersaturated aqueous solution at 80 ° C was studied. As a result of specific reversible adsorption, when forming crystalline nuclei formed, it is assumed that NaCMC changes the shape of the growing crystal, preferably forming vaterite — up to 95% in the presence of NaCMC with a molecular mass of 90 thousand during the in-teraction of CaCl2 and NaHCO3. In the presence of Mg2+ ions, CaCO3 is formed mainly in the form of aragonite, and the influence of the molecular mass of NaCMC is significantly reduced. It was established that NaCMC with Mw 90 and 250 thousand inhibits the aggregation and ag-glomeration of CaCO3 crystals, leading to a decrease in the average size of crystals from 24 to 10.6 and 16.5 microns, respectively. Under the action of NaCMC with a molecular mass of 700 thousand, on the contrary, an increase in the size of crystals to 37.2 μm is observed. It is shown that NaCMC with Mw 90 and 250 thousand slows down the speed and changes the conditions of gas hydrate formation, showing the properties of a thermodynamic and kinetic inhibitor with an efficiency that exceeds methanol by 300-450 times when used in the same dosages. The da-ta obtained indicate the promise of creating new “green” reagents of complex action for oil and gas production on the basis of sodium salt carboxymethylcellulose.