System and method for damping vibration in a drill string using a magnetorheological damper
First Claim
1. In a damping system for damping vibration in a down hole portion of a drill string, said damping system comprising a magnetorheological (MR) valve containing an MR fluid subjected to a magnetic field created by at least one coil, said MR fluid flowing through a passage formed in said MR valve, a method of operating said MR valve comprising the steps of:
- a. energizing said coil of said MR valve for a first period of time so as to create a first magnetic field that alters the viscosity of said MR fluid, said first magnetic field being sufficient to induce a first remnant magnetization in at least one component of said MR valve proximate said passage, said first remnant magnetization being at least about 12,000 Gauss;
b. substantially de-energizing said coil for a second period of time following said first period of time so as to operate said MR valve using said first remnant magnetization in said at least one component of said MR valve to create a second magnetic field that alters the viscosity of said MR fluid;
c. subjecting said at least one component of said MR valve to a demagnetization cycle over a third period of time so as to reduce said first remnant magnetization of said at least one component of said MR valve to a second remnant magnetization;
d. operating said MR valve for a fourth period of time after said demagnetization cycle in step (c).
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Accused Products
Abstract
A system for damping vibration in a drill string can include a magnetorheological fluid valve assembly having a supply of a magnetorheological fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil for inducing a magnetic field that alters the resistance of the magnetorheological fluid to flow between the first and second chambers, thereby increasing the damping provided by the valve. A remnant magnetic field is induced in one or more components of the magnetorheological fluid valve during operation that can be used to provide the magnetic field for operating the valve so as to eliminate the need to energize the coils during operation except temporarily when changing the amount of damping required, thereby eliminating the need for a turbine alternator power the magnetorheological fluid valve. A demagnetization cycle can be used to reduce the remnant magnetic field when necessary.
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Citations
35 Claims
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1. In a damping system for damping vibration in a down hole portion of a drill string, said damping system comprising a magnetorheological (MR) valve containing an MR fluid subjected to a magnetic field created by at least one coil, said MR fluid flowing through a passage formed in said MR valve, a method of operating said MR valve comprising the steps of:
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a. energizing said coil of said MR valve for a first period of time so as to create a first magnetic field that alters the viscosity of said MR fluid, said first magnetic field being sufficient to induce a first remnant magnetization in at least one component of said MR valve proximate said passage, said first remnant magnetization being at least about 12,000 Gauss; b. substantially de-energizing said coil for a second period of time following said first period of time so as to operate said MR valve using said first remnant magnetization in said at least one component of said MR valve to create a second magnetic field that alters the viscosity of said MR fluid; c. subjecting said at least one component of said MR valve to a demagnetization cycle over a third period of time so as to reduce said first remnant magnetization of said at least one component of said MR valve to a second remnant magnetization; d. operating said MR valve for a fourth period of time after said demagnetization cycle in step (c). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. In a damping system for damping vibration in a down hole portion of a drill string, said damping system comprising a magnetorheological (MR) valve containing an MR fluid subjected to a magnetic field created by at least one coil, said MR fluid flowing through a passage formed in said MR valve, a method of operating said MR valve comprising the steps of:
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a. energizing said coil of said MR valve for a first period of time so as to create a first magnetic field that alters the viscosity of said MR fluid, said first magnetic field being sufficient to induce a first remnant magnetization in at least one component of said MR valve proximate said passage; b. substantially de-energizing said coil for a second period of time following said first period of time so as to operate said MR valve using said remnant magnetization in said at least one component of said MR valve to create a second magnetic field that alters the viscosity of said MR fluid; c. measuring the strength of the magnetic field in said MR valve resulting from said remnant magnetization; d. re-energizing said coil based on said measured the strength of the magnetic field in said MR valve. - View Dependent Claims (20, 21)
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22. A magnetorheological (MR) valve assembly for damping vibration of a drill bit for drilling into an earthen formation, comprising:
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a. a first member capable of being mechanically coupled to said drill bit so that said first member is subjected to vibration from said drill bit; b. a supply of magnetorheological fluid; c. a second member, said first member mounted so as to move relative to said second member, said first and second members defining a first chamber and a second chamber for holding said magnetorheological fluid, a passage disposed between said first and second members placing said first and second chambers in fluid communication; d. at least one coil proximate said passage so that said magnetorheological fluid can be subjected to a magnetic field generated by said at least one coil when said coil is energized; e. at least a portion of one of said first and second members made from a material having a relative magnetic permeability of at least about 7000 and a coercivity of less than 1.0 Oe; f. at least a portion of the other of said first and second members being capable of having induced therein a remnant magnetic field in response to said magnetic field generated by said at least one coil that is sufficient to operate said MR valve when said coil is de-energized, said portion of said other of said first and second members in which said remnant magnetic field is induced being made from a material having a maximum remnant magnetization of at least about 12,000 Gauss and a coercivity of at least about 10 Oe and not more than about 20 Oe. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification