Hi Gholamreza,

Your question is likely an interesting question, but you need to be more precise wrt what you want to know.

It is affected by so many factors. First of all, it needs to be an old formation, affected by high temperatures, produced gas must be trapped by surrounding formations, low inorganic/high organic matter content, vein or seam needs to be thick, burial depth should be high etc. When all of these factors and some others combined, I think an anomaliously high gas containing unconventional reserve might exist.