Dampers for mitigation of downhole tool vibrations and vibration isolation device for downhole bottom hole assembly

1. A system for drilling a borehole into the earth's subsurface, the system comprising:

a drill bit configured to rotate and penetrate through the earth's subsurface; and

a vibration isolation device configured to isolate vibration that is caused by an interaction with the earth's subsurface at the drill bit, the vibration having an amplitude,

wherein the amplitude of the vibration downhole of the vibration isolation device is at least 20% higher than the amplitude of the vibration uphole of the vibration isolation device.

2. A system for drilling a borehole into the earth's subsurface, the system comprising:

a drill bit configured to rotate and penetrate through the earth's subsurface; and

a vibration isolation device configured to isolate vibration that is caused at the drill bit, the vibration isolation device including a support element configured to rotate the drill bit; and

a torque transferring element configured to transfer torque from the support element to the drill bit and further configured to isolate torsional oscillations that are created at the drill bit from the support element,

the vibration caused at the drill bit having an amplitude, wherein the amplitude of the vibration downhole of the vibration isolation device is at least 20% higher than the amplitude of the vibration uphole of the vibration isolation device.

3. The system of claim 1 , wherein the amplitude of the vibration downhole of the vibration isolation device is at least 50% higher than the amplitude of the vibration uphole of the vibration isolation device.

4. The system of claim 3 , wherein the amplitude of the vibration downhole of the vibration isolation device is at least 70% higher than the amplitude of the vibration uphole of the vibration isolation device.

5. A system for drilling a borehole into the earth's subsurface, the system comprising:

a drill bit configured to rotate and penetrate through the earth's subsurface;

a support element configured to rotate the drill bit;

a torque transferring element configured to transfer torque from the support element to the drill bit and further configured to isolate torsional oscillations that are created at the drill bit from the support element;

a damping system configured to dampen the torsional oscillations in the torque transferring element; and

a vibration isolation device configured to isolate vibration that is caused at the drill bit, the vibration having an amplitude,

wherein the amplitude of the vibration downhole of the vibration isolation device is at least 20% higher than the amplitude of the vibration uphole of the vibration isolation device.

6. The system of claim 5 , wherein the damping system comprises:

a first element; and

a second element in frictional contact with the first element,

wherein the second element moves relative to the first element with a velocity that is a sum of periodic torsional oscillations having an amplitude and a mean velocity, wherein the mean velocity is lower than the amplitude of the periodic torsional oscillations.

7. The system of claim 5 , wherein the damping system comprises:

a first element;

a second element in frictional contact with the first element; and

an adjusting element arranged to adjust a force between the first element and the second element.

8. The system of claim 2 , wherein the vibration isolation device further comprises: an end stop that limits rotational movement between the support element and the drill bit.

9. The system of claim 2 , wherein the torque transferring element has a higher flexibility per unit length than the support element.

10. The system of claim 2 , wherein the torque transferring element includes a torsional spring constant that is at least 10 times lower than a torsional spring constant of the support element.

11. The system of claim 2 , further comprising: an electrical conduit providing power and/or communication from the support element and through at least a part of the torque transferring element.

12. A method for drilling a borehole into the earth's subsurface, the method comprising:

rotating and penetrating a drill bit through the earth's subsurface; and

isolating vibration that is caused at the drill bit interacting with the earth's subsurface by a vibration isolation device, the vibration having an amplitude,

wherein the amplitude of the vibration downhole of the vibration isolation device is at least 20% higher than the amplitude of the vibration uphole of the vibration isolation device.

13. A method for drilling a borehole into the earth's subsurface, the method comprising:

rotating and penetrating a drill bit through the earth's subsurface; and

isolating vibration that is caused at the drill bit with a vibration isolation device including a support element configured to rotate the drill bit; and

a torque transferring element configured to transfer torque from the support element to the drill bit and further configured to isolate torsional oscillations that are created at the drill bit from the support element,

wherein the vibration caused at the drill bit includes an amplitude, the amplitude of the vibration caused at the drill bit downhole of the vibration isolation device is at least 20% higher than the amplitude of the vibration uphole of the vibration isolation device.

14. The method of claim 12 , wherein the amplitude of the vibration downhole of the vibration isolation device is at least 50% higher than the amplitude of the vibration uphole of the vibration isolation device.

15. A method for drilling a borehole into the earth's subsurface, the method comprising:

rotating and penetrating a drill bit through the earth's subsurface;

damping with a damping system torsional oscillations that are created at the drill bit in a torque transferring element; and

isolating vibration that is caused at the drill bit with a vibration isolation device including a support element configured to rotate the drill bit, the vibration having an amplitude;

wherein the torque transferring element is configured to transfer torque from the support element to the drill bit and further configured to isolate the torsional oscillations from the support element, and

wherein the amplitude of the vibration downhole of the vibration isolation device is at least 20% higher than the amplitude of the vibration uphole of the vibration isolation device.

16. The method of claim 15 , wherein the damping system comprises:

a first element; and

a second element in frictional contact with the first element,

wherein the second element moves relative to the first element with a velocity that is a sum of periodic torsional oscillations having an amplitude and a mean velocity, wherein the mean velocity is lower than the amplitude of the periodic torsional oscillations.

17. The method of claim 13 , wherein the vibration isolation device further comprises: an end stop that limits rotational movement between the support element and the drill bit.

18. The method of claim 13 , wherein the torque transferring element has a higher flexibility per unit length than the support element.

19. The method of claim 13 , wherein the torque transferring element includes a torsional spring constant that is at least 10 times lower than a torsional spring constant of the support element.

20. The method of claim 13 , wherein the vibration isolation device further comprises: an electrical conduit providing power and/or communication from the support element and through at least a part of the torque transferring element.