The vibration characteristics of drillstring with positive displacement motor in compound drilling Part1: Dynamical modelling and monitoring validation

The storage of hydrogen energy is one of the key difficulties in the efficient use of hydrogen. The most important thing for different storage methods is to establish the aisles of the hydrogen to storage space, and efficiently drill a few high-quality well holes. Compound drilling is one of the alternative technologies. However, the bit-rock interaction and the drill string-borehole interaction make the movement of bottom hold assembly more complex and increase the difficulty of well trajectory control. The vibration characteristics of drill string during compound drilling are not clear. The numerical simulation model of drill string with positive displacement motor is established by considering the bit-rock interaction, the rock failure behavior, the drill string-borehole interaction and the drill string structural. The mechanical parameters of shale for the numerical model are measured by wave velocities method. The simulation model is verified by the measuring and motoring data of axial force in the field. The rock element damage failure rate of compound drilling is greater than conventional drilling. The axial force and torque of bit of drill string in compound drilling is greater than that in the conventional drilling. The drill string is in contact with the wellbore in a more complicated way during compound drilling. The research results are benefit for optimal design of borehole quality.