Growth rate of a hydrate layer at the guest/liquid-water interface is analyzed considering the conjugate process of the mass-transfer and hydrate crystal growth. Hydrate-layer growth rate data in the literature are often compiled according to the system subcooling (∆T ≡ Teq − Tex, where Teq is the equilibrium dissociation temperature of the hydrate and Tex is the system temperature), suggesting...

This study aimed to construct the hydrate three-phase equilibrium curves for two typical Iranian gas reservoir samples using a high-pressure visual cell. To do so, complete analysis of the reservoir fluids was obtained by different techniques of composition analysis i.e. gas chromatography (GC) and detailed hydrocarbon analysis (DHA). Using high-pressure visual cell the hydrate phase equili...

To prevent hydrate plugging conditions in the transportation of oil/gas in multiphase flowlines, one of the key processes to control is the agglomeration/deposition of hydrate particles, which are determined by the cohesive/adhesive forces. Previous studies reporting measurements of the cohesive/adhesive force between hydrate particles used cyclopentane hydrate particles in a low-pressure micro...

In this work and in order to consider theoretically the effect of gas hydrates on the mechanical properties of their host sediments, hydrate fraction was introduced as a state variable in the framework of a Critical State model. For the proposed model, the process of de-structuration and softening of natural clay was considered as a proxy for the gas-hydrate-bearing-sediments behaviour. The dev...

−Segregation and deposition of hydrate particles observed in flowloop experiments are required to be investigated more thoroughly to understand the hydrate plugging mechanism in offshore flowlines. We used natural gas as gas phase and selected three different systems as liquid phase, which are pure water only, kinetic hydrate inhibitor added aqueous solution, and water+decane mixture, respectiv...

Gas hydrate blockage in pipelines during offshore production becomes a major problem with increasing water depth. In this work, a series of experiments on gas hydrate formation in a flow loop was performed with low flow rates of 0.33, 0.66, and 0.88 m/s; the effects of the initial subcooling, flow rate, pressure, and morphology were investigated for methane hydrate formation in the flow loop. T...

The presence of structure H (sH) methane hydrate in natural environments, in addition to the well-known structure-I (sI) and II (sII) hydrates, has recently been documented. Methane in the presence of condensates (C5-C7) forms sH hydrate at lower pressure than the sI hydrate. Thus, the occurrence of sH methane hydrate is likely to have both beneficial and negative practical implications. On the...

This paper reports the influence of sucrose on the preservation of CO2 hydrate crystal samples. The particle diameter of hydrate samples were 1.0 and 5.6-8.0 mm. Mass fraction of sucrose in the sample was 0.16. The samples were stored at the aerated condition under atmospheric pressure and at the temperature of 253 or 258 K. The results indicated that the mass fractions of CO2 hydrate in the sa...

how to cite this article: ashrafimr, azizi malamiri r, zamani gr, mohammadi m, hosseini f. sleep inducing for eeg recording in children: a comparison between oral midazolam and chloral hydrate. iran j child neurol. 2013 winter;7(1):15-19. objective electroencephalography (eeg) recording is a long duration procedure that needs patient’s cooperation for device setup and performing the procedure. ...

We performed a sequence of tests on a partially water-saturated sand sample contained in an x-raytransparent aluminum pressure vessel that is conducive to x-ray computed tomography (CT) observation. These tests were performed to gather data for estimation of thermal properties of the sand/water/gas system and the sand/hydrate/water/gas systems, as well as data to evaluate the kinetic nature of ...