621 research outputs found
Additions and corrections to Experimental measurement and phase behavior modeling of hydrogen sulfide-water binary system
No full textAntonin Chapoy, Amir H. Mohammadi, Bahman Tohidi, Alain Valtz and Dominique Richon, 2005. Experimental measurement and phase behavior modeling of hydrogen sulfide-water binary system, Industrial and Engineering Chemistry Research, Vol. 44, Iss. 19, p. 7567-7574 is available at http://dx.doi.org/10.1021/ie050201hInternational audienc
Impact of Gas Hydrate Inhibitors on Halite Scale Precipitation: An Experimental and Morphological Investigation
No full textAbstract
Inorganic scale deposition is one of the most serious flow assurance problems. One of these exotic scales is halite (NaCl). Injection of hydrate inhibitors (HIs) [methanol, monoethylene glycol (MEG), triethylene glycol (TEG)] to prevent plugging of flow lines and tubing could induce precipitation of halite scales. Thus, utilizing these chemicals might adversely affect salt solubility, causing scaling problems, particularly halite scales, in high total dissolved solid (TDS) brines. In this study, the influence of HIs on scaling of a supersaturated NaCl solution with and without inhibitor was experimentally investigated.
The results of these experiments show that increasing the concentration of HIs results in a higher amount of halite precipitation. Moreover, the effect of methanol on halite precipitation is more severe compared to MEG and TEG. On the other hand, the static efficiency results illustrate that raising the concentration of HI reduces the scale inhibition efficiency in the presence of methanol and TEG to a lower extent, while the inhibitor could have a 100% inhibition efficiency in the MEG solution. Furthermore, in the case of methanol, the optimum inhibition efficiencies at HI concentrations of 10 and 40 wt% were observed at SI concentrations of 500 and 200 ppm, respectively. Alterations in the morphology of halite in the presence of HIs were analyzed using optical microscopy and environmental scanning electron microscopy (ESEM) techniques. In this study, the effect of morphology changes of halite due to the addition of HI is addressed for the first time. These investigations can help provide a better understanding of the mechanism of halite scaling in the presence of HIs.</jats:p
Correction to: The effect of Aerobic-Resistance Training on the Expression of miR-222 and cTnT, Cx43, Ki67 Genes, and Cardiomyocyte Proliferation in Pre-Pubertal, Young, and Old Male Rats
No full textAzam Shahsavary1,
Bahman Mirzaei2,
Mohammad Reza Fadaei Chafy3,
Sarah Rajabi4
1 PhD Student of Exercise Physiology, Faculty of Physical Education and Sport Science, University of Guilan, Rasht, Iran
2 Professor of Exercise Physiology, Faculty of Physical Education and Sport Science, University of Guilan, Rasht, Iran
3 Assistant Professor, Department of Physical Education and Sport Science, Faculty of Humanities, Rasht Branch, Islamic Azad University, Rasht, Iran
4 Associate Professor, Department of Cell Engineering, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
Corresponding Author: Bahman Mirzaei - Faculty of Physical Education and Sport Science, University of Guilan, Rasht, Iran. (E-mail: [email protected])
In the article published in volume 33, issue 229, 2024, the original author order and corresponding author information were incorrect and have been corrected. The first author is Ms. Azam Shahsavary, and the second author is Dr. Bahman Mirzaei. Dr. Bahman Mirzaei is the corresponding author
A chemical based wet cold flow approach for addressing hydrate flow assurance problems
Get PDFCurrent gas hydrate flow assurance methods are becoming less economical and/or practical for deepwater operations, long tiebacks and ageing reservoirs. The industry thus needs novel flow assurance techniques to address these challenging conditions. An alternative approach called HYDRAFLOW, a chemical based wet Cold Flow method, has been presented in this thesis in which gas hydrate management, rather than prevention, is the aim. The idea is to convert most of the gas phase into hydrates and transfer it in the form of hydrate-slurry in the pipeline.
This study investigates the concept, i.e. the transportability of hydrate slurries, for different systems (low and high GOR oil systems in the presence and absence of AAs) in different operating conditions, especially in conditions where the other flow assurance solutions either cannot be applied or are not economically viable, e.g. at high watercuts or under very high degree of subcoolings. The experiments involve investigating the rheological behaviour and flow properties of hydrate slurries using the HTI-set up (Helical Tube Impeller, an apparatus designed and build in-house for measuring viscosity of hydrate slurries at high pressures). Additionally, the rate of hydrate formation in low and high oil systems and also at subzero conditions has been measured. Furthermore, the effect of key variables, (e.g. heat transfer, mass transfer, degree of subcooling, salt, anti-agglomerants (AAs) and thermodynamic inhibitors) on the rate of hydrate formation and also on the rheology of hydrate suspensions have been studied in this work. The partitioning of a commercial AA between hydrate, oil and aqueous phases and its performances in each phase have also been determined which can help for decision making about recovering and/or recycling all or part of AAs. And finally, it has been shown that hydrate flow can potentially reducing wax deposition problems in pipeline by abrasion of the deposited wax
Development of hydrate inhibition monitoring and initial formation detection techniques
Get PDFPrevention of gas hydrate blockages is a major challenge posed to the petroleum
industry because uncontrolled formation of hydrate may result in plugging of transport
pipelines, causing considerable production loss and personnel safety hazard. Injection
of hydrate inhibitors is the most common option to prevent hydrate formation.
In current industrial practice the dosage of hydrate inhibitor is estimated and injected
upstream without much downstream measurements. Therefore, hydrate blockages are
still encountered in the oil and gas industry due to lack of any hydrate monitoring
measures against unexpected changes.
In this thesis, novel techniques have been developed for monitoring hydrate inhibition
and detecting early signs of hydrate formation based on downstream sample analysis
and online measurements. The main achievements of this study can be categorised as
follow:
1. Hydrate Inhibition Monitoring Techniques: Three techniques, i.e.
conductivity-velocity (C-V) technique, water activity technique and water
content technique, have been developed for determining optimising inhibitor
injection rates
2. Initial Hydrate Formation Detection Techniques: The main objective of
detecting early signs of hydrate formation is to give the operators adequate time
to prevent hydrate formation and start remediation actions. Two techniques
including the onset of hydrate formation and compositional change have been
developed for detecting initial hydrate formation
3. Development of prototypes: Following the above fundamental studies,
prototypes of the CV and water activity methods have been developed
The development of hydrate inhibition monitoring and early hydrate formation
detection techniques opens a novel flow assurance approach for the oil and gas
industry. The developed hydrate monitoring techniques like the C-V technique, water
activity and content techniques can be used to optimise hydrate inhibitor injection. In
the near future, further development of the investigated early hydrate formation
detection techniques like gas compositional change technique could provide an
effective measure to minimise the risk of hydrate blockage
New approaches in avoiding gas hydrate problems in offshore and deepwater operation
Get PDFOil industry is facing with challenging gas hydrates and flow assurance issues in deepwater developments. The situation is not any better for Brown fields as a result of increasing water cut. The other factor which is playing an increasing role is product quality and environmental concerns, demanding reduction in chemical usage. The current industry practice for hydrate prevention is injecting hydrate inhibitors at the upstream end of pipelines based on the calculated or measured hydrate phase boundary, water cut, worst pressure and temperature conditions, and the amount of inhibitor lost to non-aqueous phases. In general, systematic ways of controlling and monitoring along the pipeline and/or downstream to examine the degree of inhibition are very limited.
Monitoring changes in the pipeline pressure drop is inadequate to provide reliable indicator for hydrate formation and deposition. Therefore, early hydrate warning and online hydrate monitoring techniques are demanded to optimise inhibitor dosage, reduce the risk of gas hydrate formation/deposition and the cost of mitigating the blockage in subsea pipelines.
The primary part of this thesis is to develop a new approach for early warning system and monitoring against initial hydrate formation. It is known that the formation of hydrates changes the water structure, which is claimed to remain in the aqueous phase for a period of time even after the dissociation of gas hydrates. This change of water structure is hypothesized to be in the form of water memory. Therefore, two hydrate early warning techniques are investigated based on the presence of water memory resulted from hydrate formation. The techniques investigated in this thesis are dielectric properties and onset of ice formation.
In this thesis, the new approach demonstrate that dielectric properties at microwave frequencies has the potential to be used as a downstream and online analysis for detecting the initial hydrate formation and/or presence of hydrate particles and/or changes in water structure due to hydrate formation. Characteristic of onset of ice formation by freezing method for water samples with and without hydrate water memory shows that samples with water memory nucleate faster than that without water memory. It is concluded that the new approach described above have potential to be developed for early warning and online hydrate monitoring. The results are very encouraging and could potentially change the industrial approach to gas hydrate control strategy.
Low Dosage Hydrate Inhibitors (LDHIs) have been applied in the field to prevent gas hydrate problems by delaying gas hydrate nucleation and/or growth and to prevent agglomeration of hydrates from growing larger enough to plug the flowline. However, the mechanism of hydrate formation and inhibition is still not well understood. It is believed micro-scale investigation could provide vital clues.
The second aim of this thesis is to investigate the inhibition mechanism of Low Dosage Hydrate Inhibitors (LDHIs) by visual observation of gas hydrate formation, growth, and morphology by means of high-pressure glass micromodels, multichanel flow conduits, and glass capillary tubes. Extensive novel data and knowledge was generated from these techniques. The finding of this study shows that various hydrate morphologies formed in the presence of different KHIs for Natural Gas Hydrate and Methane Hydrate.
It was concluded that these techniques provides a new data to supplement the lacking of knowledge on the kinetics of gas hydrate inhibition and morphologies
Fundamental controls on kinetic hydrate inhibitor performance and polymer removal from produced waters
Get PDFGas hydrate formation is one of the major concerns in the oil and gas industry, posing
considerable risks to production operation when it is not controlled. Gas hydrates are
traditionally avoided by injecting thermodynamic inhibitors (THIs) such as methanol or
MEG, however over the past two decades, in response to economic and HS&E concerns
associated with THIs, low dosage “Kinetic Hydrate Inhibitors” (KHIs) have seen
increasing use in the industry as an alternative. Although KHIs use is now quite
widespread and can offer considerable CAPEX/OPEX benefits, their hydrate inhibition
mechanisms are still relatively poorly understood.
In this thesis, a novel PVT phase behaviour/ crystal growth inhibition (CGI) method
previously developed in-house has been used to study fundamental controls on KHI
inhibition mechanisms in terms of gas and aqueous phase composition, pressure,
polymer type and presence of other pipeline chemicals. Particular focus has been placed
on gas composition, notably acid/sour gases, with results strongly suggesting that cage
occupancy patterns play a crucial role in KHI inhibition performance as a function of
pressure and presence of CO2 and H2S being a significant factor. In contrast, work on
the effect of pH does not suggest pH reduction to be the main contributor to the
observed behaviour in system containing CO2/H2S. In addition, extensive studies on
KHI-THI mixtures for different KHI polymers in multi-component natural gas systems
have revealed a potential synergistic effect of methanol up to a certain concentration,
while proving a consistent ‘top-up’ effect for ethylene glycol, opening up options for
novel combined KHI-THI inhibition strategies.
While KHIs are gaining particular interest, there is the issue of handling/disposal of
produced waters with the potential of polymer fouling problems. To address this
problem, robust evaluation of a recently developed solvent extraction based polymer
removal method shows this to have significant promise. Results also suggest that
presence of other pipeline chemicals will not affect the removal effectiveness
significantly. Work has also been expanded to examine whether the treatment chemicals
themselves might offer a novel means to create “water immiscible KHIs” for certain
applications. Results indicate that such a KHI formulation can work well, even though
the bulk of the polymer is not in the aqueous phase but in an immiscible organic
chemical. The treatment chemical extraction method also opens up options for potential
KHI recovery and re-use
An experimental and modelling investigation of the rheological properties of water/oil/gas hydrate mixtures
Get PDFIn the search for new conventional oil and gas reserves, operators are moving into more challenging reservoirs. The move of the oil and gas industry into increasingly deeper and colder locations and/or production from mature reservoirs, in which water cut can be relatively high, has faced the industry with a major challenge, because the traditional hydrate prevention methods are very expensive (i.e., high CAPEX and/or OPEX) and even, in some cases, unfeasible. In this context, hydrate management may be more economical than hydrate avoidance. Forming dispersed hydrate particles using Anti-agglomerants (AAs) is currently an attractive option for overcoming hydrate blockage problems, especially for long tieback and high subcooling systems.
This study mainly focuses on the rheological behaviour of hydrate slurry in high water-cut systems (from 60 to 80%), as these are probably the most difficult conditions for managing flow assurance issues using conventional techniques.
To engineer a controlled formation of slurry flow made up of hydrate particles in high water cut systems, it is critical that the flow characteristics of water-oil emulsions and the hydrate slurries are well understood.
In high water cut systems, by converting a certain amount of water phase into hydrate particles, the behaviour of hydrate slurry will be strongly dependent on the water-oil emulsion which acts as a carrier fluid to the hydrate particles. In this case, the behaviour of water-oil emulsions can depend on many parameters, such as the presence of natural surfactants, AAs, salt and even hydrate particles, might affect the morphology of the emulsions. So far, however, in terms of hydrate slurries, there has been very little research on the morphology of water-oil emulsions in the presence of AAs and hydrate particles. This work is initially focused on the effect of these parameters on the stability of water-in-oil (W/O) emulsions, oil-in-water (O/W) emulsions and phase inversion from W/O to O/W and vice versa.
The rheological study of hydrate slurries is a difficult subject and to date there has been little study on this issue. Most of these studies have focused on low water cut systems and there is a lack of data specifically relating to hydrate slurries in high water cut systems. In this research work, which concentrates on the rheological behaviour of hydrate slurries in
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high water cut systems, the agglomeration of hydrate particles has been shown to be responsible for the rheological behaviour of water/oil/hydrate mixtures through viscosity measurements from an in-house high pressure Helical Tube Impeller (HTI) viscometer and pressure drop measurements from a pilot-scale flow loop. The effect of oil composition, AA concentration, water cut, shear rate and salt concentration has been investigated on the rheological behaviour of hydrate slurries in high water cut systems.
Existing models to predict viscosity of hydrate slurry do not consider the effect of water-oil emulsion, which acts as a carrier fluid for transporting hydrate particles. It will lead to deviations between model and experimental data specifically relating to hydrate slurry in high water cut systems. In this study a model has been developed to predict the viscosity of water-oil emulsion in the presence of hydrate particles in high water cut systems using the concept of a bimodal mixture. In the model, water-oil emulsion and hydrate aggregates in the liquid continuous phase are treated separately as unimodal models. A new modification of Mills’ (1985) equation has been applied to describe the viscosity of unimodal hydrate suspension. The model has been validated using experimental data acquired by the HTI viscometer for water/oil/hydrate mixtures in the presence of different AA concentrations and different oil compositions. The predictions of the proposed model are in good agreement with experimental data for both experiments performed with oil-in-water and water-in-oil emulsion
Experimental investigation of semi-clathrate hydrates with application towards gas storage, transportation and separation
No full textEngineering and Physical Sciences Research Council (EPSRC
CO2 capture and storage from power plant flue gas using gas hydrate-based technologies
Get PDFThe climate system is changing globally, and there is substantial evidence that subsea
permafrost and gas hydrate reservoirs are melting in high-latitude regions of the Earth,
resulting in large volumes of CO2 (from organic carbon deposits) and CH4 (from gas
hydrate reserves) venting into the atmosphere. As one of the main contributors to global
climate change, power plants produce a substantial proportion of global anthropogenic
CO2 emissions. Here, we developed techniques to capture and storage CO2 (CCS) present
in power plant flue gases based on gas hydrate technologies. First, we experimentally
measured the thermodynamic properties of different flue gases, followed by modelling
and tuning the equations of states. Second, we proposed injection of flue gas into methane
gas hydrate reservoirs as an option for economically sustainable production of natural gas
as well as CCS. The optimum injection conditions were found and reaction kinetics was
investigated in realistic conditions and well characterised systems. Third, kinetics of flue
gas hydrate formation for both the geological storage of CO2 and the secondary sealing
of CH4/CO2 release in one simple process was investigated, followed be thoroughly
investigation of hydrate formation kinetics using a highly accurate in house developed
device. Finally, effect of the proposed methods on permeability and mechanical strength
of the geological formations was investigated
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