Characteristics of reservoir assemblage of deep CBM-bearing system in Baijiahai dome of Junggar Basin

Coal seams in Jurassic Xishanyao and Badaowan Formation were developed well in the Baijiahai dome of Junggar Basin. The burial depth of main coalbed is more than 1 500 m. Over the past ten years,the pre-production of several conventional oil and gas wells in coal seams had obtained good results,the volume of coalbed methane were more than 7 000 m3 ,which shows a good deep coalbed methane exploration prospect in Baijiahai dome. The amount of coalbed methane resources remains to be developed in Cainan oilfield. Based on the in-depth analysis of deep coalbed distribution characteristics,coal thermal evolution degree,the distribution of gas content and adjacent formation,it is considered that the Xishanyao coalbed is an independent CBM-bearing system,and the combination of Badaowan coal- bed and its adjacent sandstone is another CBM-bearing system. The superior accumulation conditions of the inner- source type and outside source type of Badaowan CBM-bearing system are enriched in CBM and sandstone gas re- sources,both two have a potential in commingled production.