Analysis of CBM reservoir damage and status of research on reservoir protection with drilling fluids in China

As the development of technology in coalbed methane, higher requirements were put forward on the coalbed methane in drilling fluids. Because coalbed methane reservoir has low porosity, low permeability, developed but heterogeneously distributed fractures, the reservoir would get irreversible damage easily during exploitation. Coalbed methane reservoir damage might cause the decline in coal bed methane recovery efficiency, increase the cost of exploitation, delay the project process, restrict CBM development effect finally. To reduce the possibility of coalbed methane reservoir damage, the paper summed up the reservoir damage mechanism in the drilling process, introduced the development process of major CBM drilling fluid, put forward the new reservoir protection methods and progress of drilling fluid, focused on the latest domestic harmless drilling fluid system, summarized the domestic development direction of reservoir protection fluid. All of those put forward new ideas on coalbed methane reservoir protection in the future.