Co-production feasibility of “Three gases” in coal measures:Discussion based on field test well

Coalbed methane,tight sand gas and shale gas (three gases) are superimposed in coal measures,and wheth- er achieving co-production successfully from on well bore determines the development efficiency and technology re- search direction of unconventional natural gases in coal measures. The paper discusses the co-production feasibility of “ three gases”,based on the analysis of “three gases” occurrence characteristics and the status of coalbed methane and tight sand gas co-production test wells in Linxing area,east margin of Ordos Basin. The results show that the key for ef- ficient co-production of “three gases” is to discharge the water from stratus by pumping equipment,and decrease the bottom hole pressure gradually. During the continuous production process,the gas and water production from one layers showed no influence to other layers. However,when the production stopped,the working water level may arise and flush into low-pressure strata due to differences in reduction degree of strata energies. Based on the field test,it can be concluded that the co-production of “three gases” is feasible,and different reservoirs show a form of river tributaries flow into the main stream or circuit parallel connection with gases being produced together when going into the well bores. The above is “parallel reservoirs combination with synergetic gas and water flow,downhole monitoring with well- head controlment”. The further researches should be focused on studying appropriate workover process to prevent res- ervoir damage during well stops.