Chemical inhibitors as potential allied for CO2 replacement in gas hydrates reservoirs: sodium chloride case study

Cantoned fluids in porous-permeable or fractured media of reservoirs have acquired during the geological time special properties. The fluids from the reservoir could be or not a mixture of reservoir water, liquid hydrocarbons and gaseous hydrocarbons. Considering if inside of a reservoir there are two types of substances like natural gas and reservoir water which may be in the form of vaporous than the condition of saturation of gases with water vaporous is fulfilled. This process is taking place due to thermodynamic equilibrium resulting the so-called gas humidity. This state corroborated with a certain chemical composition plus favourable values of pressure and temperature may be decisive in the appearance of hydrates. In this scientific paper they will be presented from a theoretical and practical point of view the favourable conditions of gas hydrates appearance and the specific ways of inhibiting the formation of this compounds. A case study in which through modelling and numerical simulation of the behaviour of a productive natural gas well will provide a series of data related to this phenomenon. The specific modelling and numerical simulation was adapted to the conditions of formation and subsequently the elimination of the appearance of hydrates.

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Influence of Sodium Chloride on the Formation and Dissociation Behavior of CO2 Gas Hydrates

The Journal of Physical Chemistry B ◽

10.1021/acs.jpcb.7b05411 ◽

2017 ◽

Vol 121 (35) ◽

pp. 8330-8337 ◽

Cited By ~ 8

Author(s):

Christine Holzammer ◽

Judith M. Schicks ◽

Stefan Will ◽

Andreas S. Braeuer

Keyword(s):

Sodium Chloride ◽

Gas Hydrates ◽

Co2 Gas

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The use of sodium chloride as strategy for improving CO2/CH4 replacement in natural gas hydrates promoted with depressurization methods

Arabian Journal of Geosciences ◽

10.1007/s12517-020-05879-6 ◽

2020 ◽

Vol 13 (18) ◽

Cited By ~ 1

Author(s):

Alberto Maria Gambelli ◽

Federico Rossi

Keyword(s):

Carbon Dioxide ◽

Sodium Chloride ◽

Natural Gas ◽

Gas Hydrates ◽

Hydrate Formation ◽

Free Water ◽

Process Efficiency ◽

Natural Gas Hydrates ◽

Replacement Process ◽

Permanent Storage

Abstract Natural gas hydrates represent a valid opportunity in terms of energy supplying, carbon dioxide permanent storage and climate change contrast. Research is more and more involved in performing CO2 replacement competitive strategies. In this context, the inhibitor effect of sodium chloride on hydrate formation and stability needs to be investigated in depth. The present work analyses how NaCl intervenes on CO2 hydrate formation, comparing results with the same typology of tests carried out with methane, in order to highlight the influence that salt produced on hydrate equilibrium conditions and possibilities which arise from here for improving the replacement process efficiency. Sodium chloride influence was then tested on five CO2/CH4 replacement tests, carried out via depressurization. In relation with the same typology of tests, realised in pure demineralised water and available elsewhere in literature, three main differences were found. Before the replacement phase, CH4 hydrate formation was particularly contained; moles of methane involved were in the range 0.059–0.103 mol. On the contrary, carbon dioxide moles entrapped into water cages were 0.085–0.206 mol or a significantly higher quantity. That may be justified by the greater presence of space and free water due to the lower CH4 hydrate formation, which led to a more massive new hydrate structure formation. Moreover, only a small part of methane moles remained entrapped into hydrates after the replacement phase (in the range of 0.023–0.042 mol), proving that, in presence of sodium chloride, CO2/CH4 exchange interested the greater part of hydrates. Thus, the possibility to conclude that sodium chloride presence during the CO2 replacement process provided positive and encouraging results in terms of methane recovery, carbon dioxide permanent storage and, consequently, replacement process efficiency.

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Experimental analysis of the CO2/CH4 Replacement Efficiency due to Sodium Chloride Presence in Natural Gas Hydrates Reservoirs

E3S Web of Conferences ◽

10.1051/e3sconf/202019708008 ◽

2020 ◽

Vol 197 ◽

pp. 08008

Author(s):

Alberto Maria Gambelli ◽

Beatrice Castellani ◽

Mirko Filipponi ◽

Andrea Nicolini ◽

Federico Rossi

Keyword(s):

Carbon Dioxide ◽

Sodium Chloride ◽

Natural Gas ◽

Gas Hydrates ◽

Energy Demand ◽

Methane Molecule ◽

Carbon Dioxide Molecule ◽

Whole Process ◽

Natural Gas Hydrates ◽

Replacement Process

Nowadays natural gas hydrates represent a promising opportunity for counteracting several crucial issues of the 21th century. They are a valid answer to the continuously increasing energy demand, moved by the global population growth; moreover, considering their conformation and the possibility of using them for carbon dioxide permanently storage, gas hydrates may become a carbon neutral energy source, where for each methane molecule recovered, another carbon dioxide molecule is entrapped in solid form. Considering that the combustion of one methane molecule for energy production leads to the formation of one CO2 molecule, the hydrates exploitation can be considered a clean process in terms of impact on the climate change. This work shows how the presence of sodium chloride affects the CO2/CH4 replacement process into a gas hydrates reservoir. Replacement experimental results carried out in pure demineralised water were compared with the same values performed in a mixture of water and salt, having a concentration of 37 g/l. Some parameters of interest were discussed, such us methane hydrates formed before the replacement process, total amount of hydrates (composed by both species) reached at the end of the whole process, CO2 moles that formed hydrate, quantity of hydrate present before the replacement process which were actually involved in the CO2/CH4 exchange and carbon dioxide amount which led to the formation of new hydrates structures.

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A Case Study Of Natural Gas Hydrates (NGH) In Offshore NW Sabah: Identification, Shallow Geohazard Implication For Exploration Drilling, Extraction Challenges And Potential Energy Resource Estimation

Bulletin of the Geological Society of Malaysia ◽

10.7186/bgsm70202005 ◽

2020 ◽

Vol 70 (1) ◽

pp. 57-75

Author(s):

John Jong ◽

◽

Hui Sin Goh ◽

Steve McGiveron ◽

Jim Fitton ◽

...

Keyword(s):

Molecular Weight ◽

Natural Gas ◽

Gas Hydrates ◽

Energy Resource ◽

Water Molecules ◽

Low Molecular Weight ◽

Natural Gas Hydrates ◽

Exploration Drilling ◽

Methane Gas Hydrates

Natural gas hydrates (NGHs), sometimes referred to as “flammable ice”, are crystalline solids, consisting of hydrocarbon gases with low molecular weight, such as methane, ethane and propane, bound with water molecules within cage-like lattices. The water molecules and low molecular weight NGH lattices are stable within a specific range of temperatures and pressures, and the source of the gases can be biogenic or thermogenic in origin. NGHs are common in the upper hundreds of metres of sub-seafloor sediments on the continental margins at water depths greater than about 500 m. Seismic reflection profiles and wireline well logs are common indicators used to identify the presence of NGHs, which are often encountered during offshore deepwater exploration drilling. They may cause geohazards such as slope instability, expulsion of the seafloor, shallow water flows and shallow gas if the stability of penetrated NGHs is disturbed and starts to dissociate. Methane gas hydrates represent a significant potential energy resource, as illustrated in this case study from offshore NW Sabah and may represent one of the world’s largest reservoirs of carbon-based fuel, with some estimates suggest that the hydrocarbons bound in the form of NGHs may rival the total energy resources contained in other conventional hydrocarbon sources. Methane can be extracted from NGHs through three methods: depressurization, inhibitor injection and thermal stimulation. However, risk associated with NGHs extraction can contribute to environmental concerns such as global warming and a decrease in microbial communities associated with methane hydrate ecosystem. Presently, in many countries, national programs exist for the research and production of natural gas from NGH deposits. As a result, hundreds of deposits have been discovered, with a few hundred wells drilled and kilometres of NGH cores studied. Hence, in the future (pending improved gas price and extraction technology), methane gas hydrates could be a vast source of natural gas supply.

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