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The natural occurrence of methane hydrates in marine sediments has been intensively studied over the past decades, and geochemical characteristic of hydrate is one of the most attractive research fields. In this paper, we discussed the geochemical anomaly during hydrate formation in porous media. By doing so, we also investigated the temperature influence on hydrate formation under isobaric condition. It turns out that subcooling is an important factor to dominate hydrate formation. Larger subcooling provides more powerful driving force for hydrate formation. During the geochemical anomaly research, six kinds of ions and the total dissolved salt (TDS) were measured before and after the experiment in different porous media. The result is that all kinds of ionic concentration increased after hydrate formation which can be defined as salting out effect mainly affected by gas consumption. But the variation ratio of different ions is not equal. Ca2+ seems to be the most significantly influenced one, and its variation ratio is up to 80%. Finally, we theoretically made a model to calculate the TDS variation, the result is in good accordance with measured one, especially when gas consumption is large.
The natural occurrence of methane hydrates in marine sediments has been intensively studied over the past decades, and geochemical characteristic of hydrate is one of the most attractive research fields. In this paper, we discussed the geochemical anomaly during hydrate formation in porous media. it is out of subcooling is an important factor to dominate hydrate formation. and the total dissolved salt (TDS) were measured before and after the experiment in different porous media. The result is that all of the kinds of ionic concentration increased after hydrate formation which can be defined as salting out effect primarily affected by gas consumption. But the variation ratio of different ions is not equal. Ca2 + seems to be the the heav significant influe Finally, we theoretically made a model to calculate the TDS variation, the result is in good accordance with measured one, especially when gas consumption is large.