GENERALIZED MATHEMATICAL MODEL OF HYDRATE FORMATION IN GAS PIPELINES

ABSTRACT Natural gas, one of the major sources of energy for the 21st century, provides more than one-fifth of the worldwide energy needs. Storing this energy in gas hydrate form presents an alternative to its storage and smart solution to its flow with the rest of the fluid without creating a difficulty in gas pipeline systems due to pressure build-up. This study was design to achieve this situation in a controlled manner using a simple mathematical model, by applying mass and momentum conservation principles in canonical form to non-isothermal multiphase flow, for predicting the onset conditions of hydrate formation and storage capacity growth of the gas hydrate in pipeline systems. Results from this developed model shows that the increase in hydrate growth, the more the hydrate storage capacity of gas within and along the gas pipeline. The developed model is therefore recommended for management of hydrate formation for natural gas storage and transportation in gas pipeline systems.

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Mathematical Model of Decomposition of Methane Hydrate during the Injection of Liquid Carbon Dioxide into a Reservoir Saturated with Methane and Its Hydrate

Mathematics ◽

10.3390/math8091482 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1482

Author(s):

Marat K. Khasanov ◽

Nail G. Musakaev ◽

Maxim V. Stolpovsky ◽

Svetlana R. Kildibaeva

Keyword(s):

Carbon Dioxide ◽

Mathematical Model ◽

Gas Hydrate ◽

Hydrate Formation ◽

Liquid Carbon ◽

Liquid Carbon Dioxide ◽

Methane Gas ◽

The Third ◽

Consistent Description ◽

The Right

The article describes a mathematical model of pumping of heated liquid carbon dioxide into a reservoir of finite extent, the pores of which in the initial state contain methane and methane gas hydrate. This model takes into account the existence in the reservoir of three characteristic regions. We call the first region “near”, the second “intermediate”, and the third “far”. According to the problem statement, the first region contains liquid CO2 and hydrate, the second region is saturated with methane and water, the third contains methane and hydrate. The main features of mathematical models that provide a consistent description of the considered processes are investigated. It was found that at sufficiently high injection pressures and low pressures at the right reservoir boundary, the boundary of carbon dioxide hydrate formation can come up with the boundary of methane gas hydrate decomposition. It is also shown that at sufficiently low values of pressure of injection of carbon dioxide and pressure at the right boundary of the reservoir, the pressure at the boundary of hydrate formation of carbon dioxide drops below the boiling pressure of carbon dioxide. In this case, for a consistent description of the considered processes, it is necessary to correct the mathematical model in order to take into account the boiling of carbon dioxide. Maps of possible solutions have been built, which show in what ranges of parameters one or another mathematical model is consistent.

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Investigating the dynamics of gas hydrates in a gas dominant flow loop

The APPEA Journal ◽

10.1071/aj10114 ◽

2011 ◽

Vol 51 (2) ◽

pp. 734

Author(s):

Yutaek Seo ◽

Mauricio Di Lorenzo ◽

Gerardo Sanchez-Soto

Keyword(s):

Steady State ◽

Gas Hydrates ◽

Gas Hydrate ◽

Gas Flow ◽

Transient Flow ◽

Hydrate Formation ◽

Hydrodynamic Condition ◽

Gas Pipelines ◽

Flow Loop ◽

Offshore Pipelines

Offshore pipelines transporting hydrocarbon fluids have to be operated with great care to avoid problems related to flow assurance. Of these possible problems, gas hydrate is dreaded as it poses the greatest risk of plugging offshore pipelines and other production systems. As the search for oil and natural gas goes into deeper and colder offshore fields, the strategies for gas hydrate mitigation are evolving to the management of hydrate risks rather than costly complete prevention. CSIRO has been developing technologies that will facilitate the production of Australian deepwater gas reserves. One of its research programs is a recently commissioned investigation into the dynamic behaviour of gas hydrates in gas pipelines using a pilot-scale 1 inch and 40 m long flow loop. This work will provide experimental results conducted in the flow loop, designed to investigate the hydrate formation characteristics in steady state and transient flow. For a given hydrodynamic condition in steady state flow, the formation and subsequent agglomeration and deposition of hydrate particles appear to occur more severely as the subcooling condition is increasing. Transient flow during a shut-in and restart operation represents a more complex scenario for hydrate formation. Although hydrates develop as a thin layer on the surface of water during the shut-in period, most of the water is quickly converted to hydrate upon restart, forming hydrate laden slurry that is transported through the pipeline by the gas flow. These results could provide valuable insights into the present operation of offshore gas pipelines.

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Large Diameter Deepwater Gas Pipelines Subjected to Global Buckling Behavior

Volume 5B: Pipelines, Risers, and Subsea Systems ◽

10.1115/omae2019-95343 ◽

2019 ◽

Author(s):

Bruno R. Antunes ◽

Rafael F. Solano ◽

Carlos O. Cardoso

Keyword(s):

Structural Integrity ◽

High Pressures ◽

Large Diameter ◽

Hydrate Formation ◽

Gas Pipelines ◽

Production Flow ◽

Buckling Behavior ◽

Production Platform ◽

Global Buckling ◽

Made In

Abstract In general, gas export pipeline designs have low restrictions concerning the flow assurance requirements, i. e., hydrate formation is not a great concern once processes in production platform facilities can significantly decrease the water content in the gas to be exported. Thus, these pipelines have only a small thickness of a single or multilayer anticorrosive coating and export gas at low temperatures. However, high pressures are required in order to overcome long distances and to increase the production flow rates. Large diameter gas pipelines submitted to high pressures even with low associated temperatures can be susceptible to global buckling, mainly if the pipelines are simply rested on a seabed of low resistance. This scenario characterizes strictly the gas pipelines installed in Brazilian Pre-Salt fields, where currently a relevant amount of export lines is operating in these conditions. Post-installation and operating pipeline surveys have identified marks on seabed confirming the buckle formation in some gas pipelines. In addition, axial movements of end equipment (PLETs) have been also observed. These issues require at least a verification and confirmation of the assumptions and predictions made in detailed design phase. This paper aims to present evaluations of the global buckling behavior of large diameter deepwater gas pipelines. Lateral buckles on very soft clayey seabed and displacements in ends and crossing locations are addressed in this work. Finally, numerical analyses confirm that gas pipelines structural integrity has not been jeopardized.

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Mathematical modeling of the equilibrium complete replacement of methane by carbon dioxide in a gas hydrate reservoir at negative temperatures

Tyumen State University Herald Physical and Mathematical Modeling Oil Gas Energy ◽

10.21684/2411-7978-2020-6-2-63-80 ◽

2020 ◽

Vol 6 (2) ◽

pp. 63-80

Author(s):

Stanislav L. Borodin ◽

Denis S. Belskikh

Keyword(s):

Carbon Dioxide ◽

Mathematical Model ◽

Gas Hydrates ◽

Hydrate Formation ◽

Complete Replacement ◽

Hydrate Reservoir ◽

Negative Temperatures ◽

Gas Hydrate Reservoir ◽

Promising Source ◽

Methane Carbon

Gas hydrates, which contain the largest amount of methane on our planet, are a promising source of natural gas after the depletion of traditional gas fields, the reserves of which are estimated to last about 50 years. Therefore, it is necessary to study the methods for extracting gas from gas hydrates in order to select the best of them and make reasoned technological and engineering decisions in the future. One of these methods is the replacement of methane in its hydrate with carbon dioxide. This work studies the construction of a mathematical model to observe this method. The following process is considered in this article: on one side of a porous reservoir, initially saturated with methane and its hydrate, carbon dioxide is injected; on the opposite side of this reservoir, methane and/or carbon dioxide are extracted. In this case, both the decomposition of methane hydrate and the formation of carbon dioxide hydrate can occur. This problem is stated in a one-dimensional linear formulation for the case of negative temperatures and gaseous carbon dioxide, which means that methane, carbon dioxide, ice, methane, and carbon dioxide hydrates may be present in the reservoir. A mathematical model is built based on the following: the laws of conservation of masses of methane, carbon dioxide, and ice; Darcy’s law for the gas phase motion; equation of state of real gas; energy equation taking into account thermal conductivity, convection, adiabatic cooling, the Joule — Thomson effect, and the release or absorption of latent heat of hydrate formation. The modelling assumes that phase transitions occur in an equilibrium mode and that methane can be completely replaced by carbon dioxide. The results of numerical experiments are presented.

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To the theory of determining the location of hydrate deposits in gas pipelines by acoustic sounding

Multiphase Systems ◽

10.21662/mfs2019.3.022 ◽

2019 ◽

Vol 14 (3) ◽

pp. 157-164

Author(s):

V.Sh. Shagapov ◽

E.V. Galiakbarova ◽

Z.R. Khakimova

Keyword(s):

Attenuation Coefficient ◽

Volume Content ◽

Acoustic Waves ◽

Solid Phase ◽

Harmonic Wave ◽

Hydrate Formation ◽

Dew Point ◽

Gas Pipelines ◽

High Frequency Region ◽

Hydrate Plug

Evolution of pressure perturbations propagating in pipeline filled with gas-and-drop medium representing “wet” methane at temperature below dew point and having damaged section, in form of extended narrowing of channel due to hydrate plug, is investigated. Hydrate formation is due to the presence of water (or its vapours) and gas, the components of which dissolve in water under certain conditions form a solid phase. Hydrate deposits help to reduce the cross-country capacity of gas pipelines and therefore their detection is a pressing task. It is proposed to solve the problem using acoustic methods. For this purpose mathematical model of propagation of acoustic waves in long-wave range in gas-and-droplet medium is considered. The horizontal pipeline appears semi-pointed, the solution is sought in the form of a harmonic wave. Wave is one-dimensional, having small amplitude of oscillations. Based on dispersion equations, dependence of phase velocity and attenuation coefficient on frequency of acoustic wave disturbance and on volume content of suspended phase (water droplets) are built. In the high frequency region, the attenuation coefficient increases with the volume content. The formulas for reflection and passage coefficients are derived taking into account pipeline narrowing due to hydrate deposits. The results of numerical calculations illustrating the dynamics of pulse signals depending on the thickness of the gas hydrate on the inner wall of the pipeline are presented. Calculations are based on forward and backward Fourier transformations and the use of software. It is established that the greater the hydrate deposit on the wall in thickness, the greater the amplitude of the returned reflected signal.

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Mathematical model of natural gas flow in pipelines in the presence of hydrate formation

Proceedings of the Mavlyutov Institute of Mechanics ◽

10.21662/uim2008.1.030 ◽

2008 ◽

Vol 6 ◽

pp. 205-209

Author(s):

V.Sh. Shagapov ◽

R.R. Urazov

Keyword(s):

Heat Transfer ◽

Mathematical Model ◽

Mass Transfer ◽

Natural Gas ◽

Phase Transformations ◽

Gas Hydrates ◽

Heat Conductivity ◽

Gas Flow ◽

Hydrate Formation ◽

Natural Gas Flow

The flow of wet natural gas in the pipeline is considered in the presence of the formation of gas hydrates on the internal walls of the channel. In the description of the phenomenon, such interrelated processes as phase transformations and mass transfer of water into the composition of gas hydrates, heat transfer between the gas stream and the environment, heat conductivity in the ground are taken into account.

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