Reservoir forming characteristics of “the three gases” in coal measure and the possibility of commingling in China

The unconventional gas resource in coal measures strata is the main part of unconventional gas. At present, the understanding of coalbed methane,shale gas and tight sandstone gas in the coal measures strata is relatively limit- ed. Also,the degrees of resources exploration and development are relatively low. According to the experiences of gas reservoir combined mining,the coal measure strata can be considered as a whole,then the cost of exploration and de- velopment on coalbed methane,shale gas and tight sandstone gas in the coal measures strata could be reduced. In ad- dition,the efficiency and single well profit of gas well could be improved. In this paper,the coalbed methane,the shale gas and the tight sandstone gas in coal measures strata are referred to as “the three coal gases”. The commingling pos- sibility of “the three coal gases” and the difficulties that commingling urgently needs were analyzed from the formation lithology distribution characteristics of coal measures strata lithology,accumulation mechanisms,reservoir characteris- tics,exploitation characteristics,etc.