Superimposing gas-bearing system in coal measures and its compatibility in Linxing block,east Ordos Basin

Superimposing gas-bearing systems and their compatibility are the key to commingling production of multi- type unconventional natural gas from coal measures. Based on the pressure,geochemistry of natural gas and production data of the Linxing block,the independent gas-bearing system was divided,and their compatibility for comingling pro- duction was investigated. Based on the differences of reservoir pressure gradient,there are at least seven sets of inde- pendent pressure systems in the target coal measure. Based on the properties of methane isotopes of natural gas from the actual production seams,three sets of combined production layers,including Tai2 to Shan2 members,He8 to He6 members,He3 member,are not connected. Based on the differences of natural gas production curve,the Shanxi and Shihezi Groups are apparently two independent gas-bearing systems. In summary,there are at least eight independent gas systems,including Qian1-Qian4 member,Qian5 member,He1-He4 member,He5 to H8 member,Shan1 to Tai1 member,Tai1-Tai2 member,Ben1 member and Ben2 member. The key factors that affect the compatibility of commingling production from independent gas-bearing systems,such as formation pressure gradient,the thickness of the gas- bearing layer,permeability,and movable water content,were extracted. Optimal partitioning method was adopted to classify the compatibility of comingling production from the different gas-bearing system in the target block. The best classification of gas-bearing system compatibility in the study area is 5-6,and the gas-bearing system compatibility of Qian5,He1-4,and He5-8 are better than those of other systems.