Study on the Borehole Stability in Liulin Coal Reservoirs

This paper studied the borehole stability in Liulin bituminous core reservoirs during under-balanced drilling. The equivalent depth method was applied to study the formation pore pressure. The floor drain test method was applied to study the ground stress. Core strength experiments combined with logging data were used in the establishment of core strength predicting model. Mechanics analysis model was founded to study the borehole stability in the core reservoir. According to the studying and analyzing results, the under-balance drilling in Liulin coal reservoirs enjoys good borehole stability.