As a potential application technology,enzymes have been used in the plugging system to remove the damage of drilling fluid to the formation,because of its many advantages such as environmental protection,no corrosion,and no loss in use.In this study,for the commonly used biodegradable drilling fluid treatment agent,two optimal degradation enzymes DPI and BG2 were selected through the viscosity decay experiment,the kinetic study of which action was carried out,and the optimal use conditions were determined.With the help of mud cake removal test and permeability recovery test,the main drilling fluid treatment agent and the best plugging agent that are most easily degraded by enzymes were determined.Combining the temporary plugging technology with the enzyme deblocking technology,three sets of enzyme deblocking drilling fluid system formulations were developed.The experimental results showed that the mud cake developed by biodegradable drilling fluid has a good removal effect,and the core permeability recovery rate can reach more than 80% after unblocking.DP 1 and BG2 have good temperature resistance,which proves that the enzyme can unplug the drilling fluid system.It has a good effect of protecting oil and gas layers,and laid a foundation for the early development of application technology of enzymes to unplug the drilling fluid.
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