Hydrate blockage observation and removal using depressurization in a fully visual flow loop

Liu, Zheyuan; Liu, Zaixing; Wang, Ji‐Guang; Yang, Mingjun; Zhao, Jiafei; Song, Yongchen

doi:10.1016/j.fuel.2021.120588

Cited by 24 publications

(5 citation statements)

References 31 publications

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“…When hydrate blockage occurs in the pipeline, the timely disappearance of hydrate blockage is also an important flow guarantee measure. The methods for understanding hydrate blockage mainly include chemical, − decompression, mechanical, and heating methods. Among them, the decompression method has the lowest operating cost and pollution and is the most commonly used industrial means.…”

Section: Prevention and Mitigation Of Hydrate Blockage In A Gas-rich ...mentioning

confidence: 99%

Hydrate Deposition Model and Flow Assurance Technology in Gas-Dominant Pipeline Transportation Systems: A Review

et al. 2022

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With the exploration and development of natural gas gradually extended to the deep sea, low-temperature and high-pressure environmental conditions and long-distance transportation make flow assurance engineers have to consider the impact of the formation and blockage of natural gas hydrates on the flow stability in the pipeline. Therefore, an inadequate understanding of the hydrate formation and plugging mechanism in a gas-rich (gas-dominant) system has become a serious obstacle to the prediction of hydrate formation and implementation of blocking prevention and control strategies. To this end, this review has conducted a comprehensive review of recent experimental investigations into hydrate formation and blockage in gas-rich systems in flow loop devices, and the physical models to characterize the clogging mechanism of hydrates established by previous scholars were summarized. In addition, the three flow patterns of the gas-rich system were divided, and the hydrate deposition mechanism corresponding to each flow pattern and the prediction model of the deposition layer thickness was summarized. Eventually, the natural gas hydrate mitigation and prophylaxis and restrain strategies used in the process of deep-sea natural gas transportation were summarized, including advantages and disadvantages of natural gas dehydration, changing the gas flow rate, and adding chemical inhibitors. The advantages and feasibility of an under-inhibited system and changing the gas flow rate for the management and prevention of hydrate blockage were emphasized. The conclusion can improve the safety index of natural gas development and transportation operations and reduce the output loss of natural gas energy and economic loss of hydrate anti-blocking.

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Section: Prevention and Mitigation Of Hydrate Blockage In A Gas-rich ...mentioning

confidence: 99%

Hydrate Deposition Model and Flow Assurance Technology in Gas-Dominant Pipeline Transportation Systems: A Review

et al. 2022

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“…Natural gas hydrate is a nonstoichiometric crystal compound with the potential to serve as a sustainable energy source, owing to its widespread presence in subsea environments, high energy density and considerable gas storage capacity. − Nevertheless, the development of hydrocarbon and gas hydrate in deepwater poses the challenging problem of hydrate blockage in pipelines, precipitated by the conducive conditions for hydrate formation . Hydrate blockage has been considered as a significant flow assurance concern in deepwater hydrocarbon resources production and transportation. − …”

Section: Introductionmentioning

confidence: 99%

Characterization of Hydrate Formation and Flow Influenced by Hydrophilic–Hydrophobic Components within a Fully Visual Rocking Cell

Lang,

Han,

Zou

et al. 2024

Energy Fuels

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The intricate interplay of crude oil composition and additives critically affects hydrate formation and flow behavior, which is significant for flow assurance particularly in deepwater. To investigate, we varied the hydrophilic and hydrophobic properties by proportioning two nonionic surfactants (Span 80 and Tween 80) and conducting hydrate formation experiments in a visual rocking cell. The results show that the increasing hydrophilic−lipophilic balance (HLB) value shifted emulsions from water-in-oil to multiple and oil-in-water phases and significantly affected the hydrate formation among different emulsion types, with a marked increase in the hydrate formation rate in the HLB range of 9 to 11. Slurries maintained flowability due to low hydrate conversion, yet higher HLB (>11) led to slight agglomeration and deposition. In addition, the impacts of water conversion were investigated by multiple pressurization, showing that the hydrate formation amount affected slurry flowability but was primarily dependent on the hydrophilicity and hydrophobicity of the surfactants. When the HLB was below 11, the final water conversion was about 80%, but the formed hydrate still exhibited good dispersion and flowability. In contrast, HLB exceeding 13 resulted in extensive adhesion and deposition on the cell walls. When the water conversion reached about 40%, flowability was completely lost and hydrate blockage occurred.

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“…Gas hydrates are ice-like solid compounds that can be naturally formed by gas and water molecules under certain pressure and temperature (P-T) conditions, where water molecules are hydrogen-bonded together to form a crystal lattice in which the gas is present as a guest molecule. − As the oil-gas exploitation and transportation are gradually shifting from land to deep sea, the high-pressure and low-temperature environment in subsea pipelines is more prone to generating gas hydrates than onshore oil and gas pipelines . Once a pipeline is blocked, it requires a long downtime for maintenance, and the economic losses caused by production interruption and hydrate removal are considerable, which becomes a significant flow assurance problem for oil and gas pipelines. − Removing hydrate blockage is one of the most important means to ensure the regular operation of pipelines, , and the breakage and shedding of hydrate often occur during the decomposition process. The shedding hydrate blocks flow downstream with fluids, which may form new unknown risks such as the blockage in the downstream pipelines .…”

Section: Introductionmentioning

confidence: 99%

“…5 Once a pipeline is blocked, it requires a long downtime for maintenance, and the economic losses caused by production interruption and hydrate removal are considerable, which becomes a significant flow assurance problem for oil and gas pipelines. 6−9 Removing hydrate blockage is one of the most important means to ensure the regular operation of pipelines, 10,11 and the breakage and shedding of hydrate often occur during the decomposition process. The shedding hydrate blocks flow downstream with fluids, which may form new unknown risks such as the blockage in the downstream pipelines.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Hydrate Decomposition on the Gas-Phase Wall Using a Rock-Flow Cell

Zhang

Song

et al. 2023

Energy Fuels

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Hydrate control has always been essential to oil and gas pipeline flow assurance work. To study the decomposition process of the hydrate deposition layer in the gas–water system, the decomposition experiments of the hydrate layer on the gas-phase pipe wall under different heating temperatures, different depressurization rates, and the combined action of heating and depressurization were carried out by using a high-pressure transparent rock-flow cell with a voltage detection system. The dynamic decomposition process was observed, and it was found that the decomposition rate was faster when decomposed by the depressurization method compared to the heating method. The decomposition process of the hydrate layer was quantitatively analyzed based on the voltage signal, and an electrical signal-based method for monitoring the decomposition of the hydrate layer on the pipe wall was proposed. The decomposition mechanism of the hydrate layer in different ways is summarized. During decomposition by heating, the hydrate layer decomposes in the mode of shrinkage ablation. During depressurization decomposition, it decomposes in the mode of differential ablation with the shedding phenomenon. The impact force generated by the gas release is the main reason for hydrate layer shedding. Shedding of the mixture of ice and hydrate occurs at depressurization rates ranging from 0.026 to 0.056 MPa/s, with the risk of ice blockage. This work provides further insight into hydrate decomposition in gas–water flow systems.

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Hydrate blockage observation and removal using depressurization in a fully visual flow loop

Cited by 24 publications

References 31 publications

Hydrate Deposition Model and Flow Assurance Technology in Gas-Dominant Pipeline Transportation Systems: A Review

Hydrate Deposition Model and Flow Assurance Technology in Gas-Dominant Pipeline Transportation Systems: A Review

Characterization of Hydrate Formation and Flow Influenced by Hydrophilic–Hydrophobic Components within a Fully Visual Rocking Cell

Experimental Study of Hydrate Decomposition on the Gas-Phase Wall Using a Rock-Flow Cell

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