Class 1 hydrates are considered as the best type of hydrates compared to Class 2 and Class 3 hydrates as energy source. Above free gas section of Class 1 hydrate, hydrate section might contain hydrate+free water (Class 1W) or hydrate+free gas (Class 1G). According to the result of the modelling studies, Class 1G is preferred compared to Class 1W. My question is that in nature which type is common, whether Class 1G or Class 1W? I could not obtain any articles or reference about it. Just I know Messoyakha field (permafrost) in Russia is Class 1G type.
Gas Hydrates: Immense Energy Potential and Environmental Challenges
By Carlo Giavarini, Keith Hester
Go through this google book; if it is helpful. I think Class 1G is common.
https://books.google.co.in/books?id=a8XrILXdyOMC&pg=PA119&lpg=PA119&dq=Class+1G+hydrates&source=bl&ots=rmZ_VK1oYK&sig=zqLS_JqfMtPY0PFNqz4R7tzhCRI&hl=en&sa=X&ved=0ahUKEwjf4La3pMfKAhUFcY4KHXdmAZ8Q6AEIQjAG#v=onepage&q=Class%201G%20hydrates&f=false
Dear Kumar,
Thank you very much for your answer. I have found similar things in this article in which it was said that "Class 1G hydrates are likely to be common compared to Class 1W hydrates":
Moridis, G. J., Reagan, M. T., & Zhang, K. (2008). the Use of Horizontal Wells in Gas Production from Hydrate Accumulations. Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008), Vancouver, British Columbia, Canada, July 6-10, 2008.
But only "Class 1G hydrates are likely to be common compared to Class 1W hydrates" this sentence is available in literature.
My thought is that If gas migrates through water saturated zone, Class 1G hydrate forms but if water and dissolved CH4 moves to the reservoir rock, it is likely that Class 1W forms. I guess much more data is needed to make any conclusion because gas hydrate studies are still immature.
Thank you again for your suggestion Dear Kumar.