Mechanical borehole stability test study in highly-dipped laminated formation

Simulation test is conducted to study the factors that affect the borehole instability while drilling in highly-dipped forma- tion. The maximum load capacity in different angles of dip-formation is tested with the true-triaxial test system. The orrelation between dip and borehole stability is conirmed. Simultaneously the stable time under different luid column pressure is also tested with the same system. It is revealed that the stable time will be increased by increasing the mud column pressure in low-dip formations. But the result may be opposite in highly-dipped formations.