scholarly journals Research on Gas Hydrate Plug Formation under Pipeline-Like Conditions

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Florian Stephan Merkel ◽  
Carsten Schmuck ◽  
Heyko Jürgen Schultz ◽  
Timo Alexander Scholz ◽  
Sven Wolinski
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Gas Flow ◽  
Energy Resource ◽  
Gas Storage ◽  
Natural Gases ◽  
Induction Times ◽  
Operational Expenditure ◽  
Hydrate Plug ◽  
Plug Formation

Hydrates of natural gases like methane have become subject of great interest over the last few decades, mainly because of their potential as energy resource. The exploitation of these natural gases from gas hydrates is seen as a promising mean to solve future energetic problems. Furthermore, gas hydrates play an important role in gas transportation and gas storage: in pipelines, particularly in tubes and valves, gas hydrates are formed and obstruct the gas flow. This phenomenon is called “plugging” and causes high operational expenditure as well as precarious safety conditions. In this work, research on the formation of gas hydrates under pipeline-like conditions, with the aim to predict induction times as a mean to evaluate the plugging potential, is described.

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

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.

Depressurization-Induced Gas Production From Class-1 Hydrate Deposits

2007 ◽  
Vol 10 (05) ◽  
pp. 458-481 ◽  
Author(s):  
George J. Moridis ◽  
Michael Brendon Kowalsky ◽  
Karsten Pruess
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Energy Content ◽  
Energy Resource ◽  
Deep Ocean ◽  
Gas Production ◽  
Pressure Effects ◽  
Phase Zone ◽  
Two Phase ◽  
Class 1

Summary Class 1 hydrate deposits are characterized by a hydrate-bearing layer underlain by a two-phase zone involving mobile gas. Two kinds of deposits are investigated. The first involves water and hydrate in the hydrate zone (Class 1W), while the second involves gas and hydrate (Class 1G). We introduce new models to describe the effect of the presence of hydrates on the wettability properties of porous media. We determine that large volumes of gas can be readily produced at high rates for long times from Class 1 gas-hydrate accumulations by means of depressurization-induced dissociation using conventional technology. Dissociation in Class 1W deposits proceeds in distinct stages, while it is continuous in Class 1G deposits. To avoid blockage caused by hydrate formation in the vicinity of the well, wellbore heating is a necessity in production from Class 1 hydrates. Class 1W hydrates are shown to contribute up to 65% of the production rate and up to 45% of the cumulative volume of produced gas; the corresponding numbers for Class 1G hydrates are 75% and 54%. Production from both Class 1W and Class 1G deposits leads to the emergence of a second dissociation front (in addition to the original ascending hydrate interface) that forms at the top of the hydrate interval and advances downward. In both kinds of deposits, capillary pressure effects lead to hydrate lensing (i.e., the emergence of distinct banded structures of alternating high/low hydrate saturation, which form channels and shells and have a significant effect on production). Introduction Background. Gas hydrates are solid crystalline compounds in which gas molecules (referred to as guests) are lodged within the lattices of ice crystals (called hosts). Gas-hydrate deposits occur in two distinctly different geologic settings where the necessary favorable thermodynamic conditions exist for their formation and stability: in the permafrost and in deep ocean sediments. Because of different formation processes, these two types of accumulations have distinctly different attributes. Although there has been no systematic effort to map and evaluate this resource, and current estimates vary widely the consensus is that the worldwide quantity of hydrocarbon-gas hydrates is vast (Sloan 1998). Even the most conservative estimate surpasses by a factor of two the energy content of the total fossil-fuel reserves recoverable by conventional methods. The sheer magnitude of this resource commands attention as a potential energy resource, even if only a limited number of hydrate deposits are attractive production targets and/or only a fraction of the trapped gas may be recoverable. As current energy economics make gas production from unconventional resources increasingly appealing (or, at a minimum, less prohibitive), the potential of hydrate accumulations clearly demands technical and economic evaluation. The attractiveness of hydrates is further augmented by the environmental desirability of gas (as opposed to solid and liquid) fuels. Gas from hydrates is produced by inducing dissociation by one of the following three main methods (Sloan 1998) (or combinations thereof):depressurization, which involves pressure lowering below the equilibrium hydration pressure at the prevailing temperature;thermal stimulation, in which the temperature is raised above the equilibrium hydration temperature at the prevailing pressure; andthe use of hydration inhibitors (such as salts and alcohols).

Gas Hydrate Deposition in Flowlines: A Challenging Problem in Flow Assurance

2013 ◽  
Author(s):  
Giovanny A. Grasso ◽  
Prithvi Vijayamohan ◽  
E. Dendy Sloan ◽  
Carolyn A. Koh ◽  
Amadeu K. Sum
Keyword(s):  
Gas Hydrate ◽  
Preliminary Investigation ◽  
Pass System ◽  
Hydrate Deposition ◽  
Liquid Systems ◽  
Multiphase Fluid Flow ◽  
Multiphase Fluid ◽  
Pipeline Wall ◽  
Hydrate Plug ◽  
Plug Formation

Gas hydrate deposition on the pipeline wall is one of the key processes leading to hydrate plug formation; however, this phenomenon is still poorly understood and missing in a full comprehensive model for simulating/predicting hydrate cold slurry flow (1). To gain a better understanding on hydrate deposition, we have performed several experiments of hydrate deposition on a solid surface for liquid systems (gas free). This preliminary investigation helps to better understand the challenges for further investigations of hydrate deposition in multiphase fluid flow. From this research, the importance of maintaining a constant concentration of the hydrate former and simulating a single pass system were identified; the challenges to control the temperature of the deposition surface, as well as the gradient of the temperature between the fluid and metal surface to promote deposition have also been identified.

scholarly journals Influence of Gas Supply Changes on the Formation Process of Complex Mixed Gas Hydrates

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 3039
Author(s):  
Mengdi Pan ◽  
Judith M. Schicks
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Formation Process ◽  
Gas Flow ◽  
Hydrate Formation ◽  
Experimental Investigations ◽  
Gas Composition ◽  
Mixed Gas ◽  
Hydrate Phase ◽  
Gas Supply

Natural gas hydrate occurrences contain predominantly methane; however, there are increasing reports of complex mixed gas hydrates and coexisting hydrate phases. Changes in the feed gas composition due to the preferred incorporation of certain components into the hydrate phase and an inadequate gas supply is often assumed to be the cause of coexisting hydrate phases. This could also be the case for the gas hydrate system in Qilian Mountain permafrost (QMP), which is mainly controlled by pores and fractures with complex gas compositions. This study is dedicated to the experimental investigations on the formation process of mixed gas hydrates based on the reservoir conditions in QMP. Hydrates were synthesized from water and a gas mixture under different gas supply conditions to study the effects on the hydrate formation process. In situ Raman spectroscopic measurements and microscopic observations were applied to record changes in both gas and hydrate phase over the whole formation process. The results demonstrated the effects of gas flow on the composition of the resulting hydrate phase, indicating a competitive enclathration of guest molecules into the hydrate lattice depending on their properties. Another observation was that despite significant changes in the gas composition, no coexisting hydrate phases were formed.

scholarly journals An insight into the role of the association equations of states in gas hydrate modeling: a review

2020 ◽  
Vol 17 (5) ◽  
pp. 1432-1450
Author(s):  
Feridun Esmaeilzadeh ◽  
Nazanin Hamedi ◽  
Dornaz Karimipourfard ◽  
Ali Rasoolzadeh
Keyword(s):  
Thermodynamic Modeling ◽  
Gas Hydrates ◽  
Gas Hydrate ◽  
Wide Spectrum ◽  
Energy Resource ◽  
Intermolecular Forces ◽  
Green Energy ◽  
Water Desalination ◽  
Number Of Publications ◽  
And Control

Abstract Encouraged by the wide spectrum of novel applications of gas hydrates, e.g., energy recovery, gas separation, gas storage, gas transportation, water desalination, and hydrogen hydrate as a green energy resource, as well as CO2 capturing, many scientists have focused their attention on investigating this important phenomenon. Of course, from an engineering viewpoint, the mathematical modeling of gas hydrates is of paramount importance, as anticipation of gas hydrate stability conditions is effective in the design and control of industrial processes. Overall, the thermodynamic modeling of gas hydrate can be tackled as an equilibration of three phases, i.e., liquid, gas, and solid hydrate. The inseparable component in all hydrate systems, water, is highly polar and non-ideal, necessitating the use of more advanced equation of states (EoSs) that take into account more intermolecular forces for thermodynamic modeling of these systems. Motivated by the ever-increasing number of publications on this topic, this study aims to review the application of associating EoSs for the thermodynamic modeling of gas hydrates. Three most important hydrate-based models available in the literature including the van der Waals–Platteeuw (vdW–P) model, Chen–Guo model, and Klauda–Sandler model coupled with CPA and SAFT EoSs were investigated and compared with cubic EoSs. It was concluded that the CPA and SAFT EoSs gave very accurate results for hydrate systems as they take into account the association interactions, which are very crucial in gas hydrate systems in which water, methanol, glycols, and other types of associating compounds are available. Moreover, it was concluded that the CPA EoS is easier to use than the SAFT-type EoSs and our suggestion for the gas hydrate systems is the CPA EoS.

scholarly journals Physical Properties of Gas Hydrates: A Review

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Jorge F. Gabitto ◽  
Costas Tsouris
Keyword(s):  
Natural Gas ◽  
Physical Properties ◽  
Gas Hydrates ◽  
Gas Hydrate ◽  
Energy Resource ◽  
Field Measurements ◽  
Detection Methods ◽  
Natural Gas Hydrate ◽  
Methane Gas ◽  
Hydrate Bearing Sediments

Methane gas hydrates in sediments have been studied by several investigators as a possible future energy resource. Recent hydrate reserves have been estimated at approximately 1016 m3 of methane gas worldwide at standard temperature and pressure conditions. In situ dissociation of natural gas hydrate is necessary in order to commercially exploit the resource from the natural-gas-hydrate-bearing sediment. The presence of gas hydrates in sediments dramatically alters some of the normal physical properties of the sediment. These changes can be detected by field measurements and by down-hole logs. An understanding of the physical properties of hydrate-bearing sediments is necessary for interpretation of geophysical data collected in field settings, borehole, and slope stability analyses; reservoir simulation; and production models. This work reviews information available in literature related to the physical properties of sediments containing gas hydrates. A brief review of the physical properties of bulk gas hydrates is included. Detection methods, morphology, and relevant physical properties of gas-hydrate-bearing sediments are also discussed.

Gas hydrate plug formation in partially-dispersed water–oil systems

2016 ◽  
Vol 140 ◽  
pp. 337-347 ◽  
Author(s):  
Masoumeh Akhfash ◽  
Zachary M. Aman ◽  
Sang Yoon Ahn ◽  
Michael L. Johns ◽  
Eric F. May
Keyword(s):  
Gas Hydrate ◽  
Hydrate Plug ◽  
Plug Formation

Thermodynamic Modelling of Gas Hydrate Formation in the Presence of Inhibitors and the Consideration of their Effect

2014 ◽  
Vol 14 (1) ◽  
pp. 45
Author(s):  
Peyman Sabzi ◽  
Saheb Noroozi
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Low Temperatures ◽  
Hydrate Formation ◽  
Transportation Systems ◽  
Flow Lines ◽  
Main Approach ◽  
Efficient Inhibitor ◽  
System A ◽  
Gas Hydrate Formation

Gas hydrates formation is considered as one the greatest obstacles in gas transportation systems. Problems related to gas hydrate formation is more severe when dealing with transportation at low temperatures of deep water. In order to avoid formation of Gas hydrates, different inhibitors are used. Methanol is one of the most common and economically efficient inhibitor. Adding methanol to the flow lines, changes the thermodynamic equilibrium situation of the system. In order to predict these changes in thermodynamic behavior of the system, a series of modelings are performed using Matlab software in this paper. The main approach in this modeling is on the basis of Van der Waals and Plateau's thermodynamic approach. The obtained results of a system containing water, Methane and Methanol showed that hydrate formation pressure increases due to the increase of inhibitor amount in constant temperature and this increase is more in higher temperatures. Furthermore, these results were in harmony with the available empirical data.Keywords: Gas hydrates, thermodynamic inhibitor, modelling, pipeline blockage

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