Gas hydrates and clathrates: Flow assurance, environmental and economic perspectives and the Nigerian liquified natural gas project

Gbaruko, B.C.; Igwe, J.C.; Gbaruko, P.N.; Nwokeoma, R.C.

doi:10.1016/j.petrol.2005.12.011

Cited by 87 publications

(98 citation statements)

References 23 publications

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“…5 Hydrates may also form naturally in oceanic sediments or sediments under the permafrost, where thermodynamic conditions such as high pressures and low temperatures exist. [6][7] There are active methods to prevent the formation and agglomeration of hydrate inside oil and gas pipelines including external heating of the pipelines, 5,8 addition of water miscible alcohols and glycols such as methanol or ethylene glycol to shift the thermodynamic equilibrium away from typical pipeline conditions, 9 and the use of low-dosage kinetic inhibitors or anti-agglomerates to reduce the rate of nucleation and growth of hydrates, or to prevent the agglomeration of hydrate particles into larger structures which increase the risk of blockage. 4,10 Gas hydrate blockages pose an unresolved flow assurance challenge for hydrocarbon production with high watercuts because hydrate inhibition with thermodynamic inhibitors, such as methanol, often becomes economically and logistically unpractical.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][8][9][10][11] Therefore, passive methods such as surface modifications of pipeline inner walls are of interest for two reasons; firstly in order to minimize nucleation and/or deposition of hydrates on the pipeline wall, and secondly, in the case of wall formation or deposition to reduce the hydrate adhesion strength. 12 In order to reduce the adhesion of ice to underlying substrates, we have recently developed durable and mechanically-robust bilayer polymer coatings which are covalently bonded to silicon and steel substrates through an in-situ grafting mechanism using the initiated chemical vapor deposition (iCVD) technique.…”

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confidence: 99%

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Investigation into the Formation and Adhesion of Cyclopentane Hydrates on Mechanically Robust Vapor-Deposited Polymeric Coatings

Sojoudi¹,

Walsh

Gleason³

et al. 2015

Langmuir

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Blockage of pipelines by formation and accumulation of clathrate hydrates of natural gasses (also called gas hydrates) can compromise project safety and economics in oil and gas operations, particularly at high pressures and low temperatures such as those found in subsea or arctic environments. Cyclopentane (CyC5) hydrate has attracted interest as a model system for studying natural gas hydrates, because CyC5, like typical natural gas hydrate formers, is almost fully immiscible in water; and thus CyC5 hydrate formation is governed not only by thermodynamic phase considerations but also kinetic factors such as hydrocarbon/water interfacial area and mass & heat transfer, as for natural gas hydrates. We present a macroscale investigation of the formation and adhesion strength of CyC5 hydrate deposits on bilayer polymer coatings with a range of wettabilities. The polymeric bilayer coatings are developed using initiated chemical vapor deposition (iCVD) of a mechanically-robust and 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 densely-cross-linked polymeric base layer (poly-divinyl benzene or pDVB) that is capped with a covalently-attached thin hydrate-phobic fluorine-rich top layer (polyperfluorodecylacrylate or pPFDA). The CyC5 hydrates are formed from CyC5-in-water emulsions, and differential scanning calorimetry (DSC) is used to confirm the thermal dissociation properties of the solid hydrate deposits. We also investigate the adhesion of the CyC5 hydrate deposits on bare and bilayer polymer-coated silicon and steel substrates.Goniometric measurements with drops of CyC5-in-water emulsions on the coated steel substrates exhibit advancing contact angles of 148.3º ± 4.5º and receding contact angles of 142.5º ± 9.8º, indicating the strongly emulsion-repelling nature of the iCVD coatings. The adhesion strength of the CyC5 hydrate deposits reduced from 220±45 kPa on rough steel substrates to 20±17 kPa on the polymer-coated steel substrates. The measured strength of CyC5 hydrate adhesion is found to correlate very well with the work of adhesion between the emulsion droplets used to form the CyC5 hydrate and the underlying substrates.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Investigation into the Formation and Adhesion of Cyclopentane Hydrates on Mechanically Robust Vapor-Deposited Polymeric Coatings

Sojoudi¹,

Walsh

Gleason³

et al. 2015

Langmuir

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“…The success of the explicit approach to hydrogen bonds in water ice has further significance in describing clathrate structures. Methane hydrates, in particular are the subject of renewed research as, found on the ocean floor and in polar regions they are estimated to contain up to 12% of all the organic carbon on Earth [81], making them an important energy resource. In addition, hydrates are often formed within gas pipelines, where they are unwanted and cause significant damage [82].…”

Section: Water Ice and Hydrate Structuresmentioning

confidence: 99%

Explicit treatment of hydrogen bonds in the universal force field: Validation and application for metal-organic frameworks, hydrates, and host-guest complexes

Coupry

Addicoat

Heine

2017

The Journal of Chemical Physics

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A straightforward means to include explicit hydrogen bonds within the Universal Force Field is presented. Instead of treating hydrogen bonds as non-bonded interaction subjected to electrostatic and Lennard-Jones potentials, we introduce an explicit bond with negligible bond order, thus maintaining the structural integrity of the H-bonded complexes and avoiding the necessity to assign arbitrary charges to the system. The explicit hydrogen bond changes the coordination number of the acceptor site and the approach is thus most suitable for systems with under-coordinated atoms, such as many metal-organic frameworks, however, it also shows excellent performance for other systems involving a hydrogen-bonded framework. In particular, it is an excellent means for creating starting structures for molecular dynamics and for investigations employing more sophisticated methods.The approach is validated for the hydrogen bonded complexes in the S22 dataset and then employed for a set of metal-organic frameworks from the Computation-Ready Experimental (CoRE) database and several hydrogen bonded crystals including water ice and clathrates. We show that direct inclusion of hydrogen bonds reduces the maximum error in predicted cell parameters from 66% to only 14% and the mean unsigned error is similarly reduced from 14% to only 4%. We posit that with the inclusion of hydrogen bonding, the solvent-mediated breathing of frameworks such as MIL-53 is now accessible to rapid UFF calculations, which will further the aim of rapid computational scanning of metal-organic frameworks while providing better starting points for electronic structure calculations.

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“…Diluted in water to below 60%, it maintains its efficiency over several months and can be stored without risk. Moreover, tungsten occurs naturally as tungstate (WO 4 2À ) and its level of toxicity is rather lower than other heavy metals (International Tungsten Industry association) [31]. Various catalyst amounts and reaction times were tested to determine the appropriate conditions.…”

Section: Isoamyl Alcohol Oxidationmentioning

confidence: 99%

Green syntheses of biobased solvents

Bandres

Thiébaud‐Roux

et al. 2010

Comptes Rendus. Chimie

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Gas hydrates and clathrates: Flow assurance, environmental and economic perspectives and the Nigerian liquified natural gas project

Cited by 87 publications

References 23 publications

Investigation into the Formation and Adhesion of Cyclopentane Hydrates on Mechanically Robust Vapor-Deposited Polymeric Coatings

Investigation into the Formation and Adhesion of Cyclopentane Hydrates on Mechanically Robust Vapor-Deposited Polymeric Coatings

Explicit treatment of hydrogen bonds in the universal force field: Validation and application for metal-organic frameworks, hydrates, and host-guest complexes

Green syntheses of biobased solvents

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