Unconventional natural gas reserves are abundant on earth. Natural gas is regarded as a substitute for conventional
coal and oil because it is cleaner. Preliminary gathering and transportation technologies suited for coalbed methane, shale gas and
tight sandstone gas have been developed in China. In recent years, the feasibility of multi-gas co-production (co-exploration and
concurrent production of coalbed methane, shale gas and tight sandstone gas) has been proved by a series of exploratory developments
and pilot tests. Through multi-gas co-production, the costs will reduce and economic efficiency and resource utilization
will improve. However, these technologies are still at an initial stage. In addition to the difficulties in a single unconventional
natural gas gathering and transportation system, there is another key issue which needs to be solved. Namely, how to overcome
the conflicts between gases of different pressure levels in a diverse pressure gathering system. This is mainly in: (1) the pressure
matching between production layers, individual wells and gathering networks, (2) the coordinated utilization of energy among
the gases of different pressure levels, (3) the intelligent matching of process parameters in gathering and transportation systems.
In order to produce gas from these different sources in an economical and efficient way, the difficulties mentioned above will
need to be solved by carrying out the following studies: (1) Techniques for integration of gas production and gathering and
transportation for multi-gas co-production, (2) simulation and optimization technique of multi-gas co-production gathering
systems containing ejector devices, (3) intelligent matching techniques for the gathering and transportation process parameters
considering the system efficiency.