Active torsional isolator and damper
An active system is provided that changes the mechanical stiffness of a BHA during drilling to prevent/reduce damage to a BHA due to vibrations. The active system uses a combination of mechanical and electronic systems to change the physical characteristics of a BHA that govern the natural frequencies thereof. The active system can change the mechanical stiffness of a BHA by switching between two different coupling modes for connecting sections or portions of the BHA. An active torsional isolator and damper (ATID) can be used to switch between the different coupling modes. In one example, the ATID includes: (1) a dynamic coupler configured to connect a first portion of a BHA to a second portion of the BHA according to different coupling modes, and (2) a processor configured to control switching of the dynamic coupler between the different coupling modes during a drilling operation of a drill bit.
1 . A bottom hole assembly (BHA), comprising:
a drill bit; and
an active torsional isolator and damper (ATID) that connects a first portion of the BHA to a second portion of the BHA using a fluid according to different coupling modes and changes a resonance frequency of the BHA by switching between the different coupling modes during drilling by the drill bit according to a switching time interval that is less than a resonance time interval for the BHA to achieve a resonance frequency associated with either of the different coupling modes, wherein the first portion includes the drill bit and the different coupling modes include at least one coupling mode that restricts torsional movement between the first portion relative to the second portion, wherein a duty cycle of the switching time interval varies based on a signature of the resonance frequency.
2 . The BHA as recited in claim 1 , wherein the ATID includes a dynamic coupler configured to connect the first and second portions of the BHA, wherein one or more components of the dynamic coupler are changed when switching between the different coupling modes.
3 . The BHA as recited in claim 2 , wherein the one or more components include an outer housing, an inner section, and fluid cavities defined by the outer housing and the inner section, wherein the fluid is located in the fluid cavities and couples the inner section to the outer housing, wherein the inner section corresponds to the first portion of the BHA and the outer housing corresponds to the second portion of the BHA.
4 . The BHA as recited in claim 3 , wherein the one or more components include electromagnets operable by the processor, permanent magnets, or a combination thereof that assist in restricting the torsional movement of the inner section relative to the outer housing in a rigid mode.
5 . The BHA as recited in claim 2 , wherein the one or more components include one or more of the fluid, fluid cavities, springs located in the fluid cavities, a flow controller for the fluid, a clutch, or one or more of electromagnets.
6 . The BHA as recited in claim 2 , wherein the ATID further includes a processor configured to control the switching of the dynamic coupler between the different coupling modes during the drilling by the drill bit.
7 . The BHA as recited in claim 6 , wherein the one or more components include one or more electromagnets, the dynamic coupler includes a smart fluid, and the processor is configured to operate the one or more electromagnets to increase viscosity of the smart fluid to restrict the torsional movement.
8 . A method of drilling a wellbore, comprising:
operating a drill bit in the wellbore, wherein the drill bit is part of a BHA; and
altering a mass of the BHA during the operating according to different coupling modes, wherein one of the different coupling modes restricts torsional movement of an inner section of the BHA relative to an outer section of the BHA and at least a portion of the inner section is located within at least a portion of the outer section, wherein the altering includes switching between the different coupling modes using a switching time interval that is less than a resonance time interval for the BHA to achieve a resonance frequency associated with either of the different coupling modes and is variable based on an indication of resonance in either of the different coupling modes.
9 . The method as recited in claim 8 , wherein the altering includes changing a connection between the inner section and the outer section according to the different coupling modes.
10 . The method of drilling as recited in claim 9 , wherein the altering includes using one or more magnets to assist in changing the connection between the inner section and the outer section according to the different coupling modes.
11 . The method of drilling as recited in claim 9 , wherein the different coupling modes include a rigid mode and a relaxed mode, wherein a torsional rigidity of the BHA is greater in the rigid mode compared to the relaxed mode.