摘要
Coal-bearing series, which expel bulk of organic acid during early burial stages is the base of deep basin gas accumulation. Organic acid would dissolve aluminum silicate minerals and cause rocks loosen and easy to be compacted. Furthermore, with the increasing of temperature, organic complex with Al3+ and Si2+ in from formation water decomposes into silica sediments causing high density of regional coal series sandstones. With the increasing of buried depth from Late Jurassic to Early Cretaceous, accompanied with the thermal event and the conversion procedure from lean coal to anthracite, mass gas gradually diluted, diffused, and dissolved formation water, and ultimately forming deep basin gas accumulation.