Design and Performance Analysis of Drillstring Vibration Energy Harvester

Aiming at the power supply problem of downhole measurement and control instruments, two kinds of vibration energy harvesters, axial vibration energy harvester and lateral vibration energy harvester, are designed in this paper to harvest the axial, lateral, and torsional vibration energy of the drillstring. The mathematical models of the two harvesters are established and the vibration coupling between the harvesters and the drillstring is realized by sharing the node with the drillstring. The performances of the two kinds of harvesters are numerically simulated. The results show that the output power of the axial harvester changes periodically with the change of its installation depth and the number of cycles increases with the increase of the drillstring length. The larger the natural frequency of the axial harvester, the smaller the amplitude of output power fluctuation with depth. When the rotating speed matches the natural frequency of the axial harvester, the maximum output power can reach 1.4 W. The outpower of the lateral VEH is maximum in the possible buckling section near the bit and the maximum output power is about 10 W. The results show that the output power of the designed vibration energy harvester can meet the power demand of most downhole measurement and control instruments.