SYSTEM AND METHOD FOR DAMPING VIBRATION IN A DRILL STRING USING A MAGNETORHEOLOGICAL DAMPER
First Claim
1. A method of damping vibration in a down hole portion of a drill string drilling into an earthen formation, comprising the steps of:
- a) providing a magnetorheological (MR) valve having at least one coil and containing an MR fluid that flows through a passage formed in said MR valve, said MR valve having associated therewith a limiting hysteresis loop relating the strength of the magnetic field in said valve to the current supplied to said coil;
b) supplying a varying current to said coil so as to subject said MR fluid in said MR valve to a varying magnetic field created by said coil;
c) determining the magnetization history of said MR valve as said current supplied to said coil varies by measuring said varying current and calculating the strength of said magnetic field created by said varying current, said strength of said magnetic field determined using information representative of said limiting hysteresis loop associated with said MR valve;
d) determining the current to be supplied to said coil that will result in a desired magnetic field using said magnetization history of said MR valve determined in step (c);
e) supplying said current determined in step (d) to said coil so as to substantially obtain said desired magnetic field.
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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 remanent magnetic field is induced in the 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 except temporarily when changing the amount of damping required The current to be supplied to the coil for inducing a desired magnetic field in the valve is determined based on the limiting hysteresis curve of the valve and the history of the magnetization of the value using a binary search methodology. The history of the magnetization of the valve is expressed as a series of sets of current and it resulting magnetization at which the current experienced a reversal compared to prior values of the current.
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Citations
21 Claims
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1. A method of damping vibration in a down hole portion of a drill string drilling into an earthen formation, comprising the steps of:
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a) providing a magnetorheological (MR) valve having at least one coil and containing an MR fluid that flows through a passage formed in said MR valve, said MR valve having associated therewith a limiting hysteresis loop relating the strength of the magnetic field in said valve to the current supplied to said coil; b) supplying a varying current to said coil so as to subject said MR fluid in said MR valve to a varying magnetic field created by said coil; c) determining the magnetization history of said MR valve as said current supplied to said coil varies by measuring said varying current and calculating the strength of said magnetic field created by said varying current, said strength of said magnetic field determined using information representative of said limiting hysteresis loop associated with said MR valve; d) determining the current to be supplied to said coil that will result in a desired magnetic field using said magnetization history of said MR valve determined in step (c); e) supplying said current determined in step (d) to said coil so as to substantially obtain said desired magnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of damping vibration in a down hole portion of a drill string, said drill string 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) supplying current to 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 remanent 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 first remanent 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) at least partially demagnetizing said at least one component of said MR valve so as to reduce said first remanent magnetization of said at least one component of said MR valve to a second remanent magnetization, said demagnetizing step comprising the steps of; (1) determining the magnetization history of said MR valve as said current supplied to said coil varies by measuring said varying current and calculating the strength of said magnetic field created by said varying current, said strength of said magnetic field determined using information representative of said limiting hysteresis loop associated with said MR valve; (2) determining the current to be supplied to said coil that will result in at least partially demagnetizing said at least one component using said magnetization history of said MR valve determined in step (c)(1); (3) supplying said current determined in step (c)(2) to said coil so as to at least partially demagnetize said at least one component; (d) operating said MR valve for a third period of time after said at least partial demagnetization in step (c).
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16. A magnetorheological (MR) valve assembly for damping vibration of a drill bit for drilling into an earthen formation, comprising:
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a) at least one coil to which current is supplied and an MR fluid that flows through a passage formed in said MR valve proximate said coil, the current supplied to said coil varying so as to subject said MR fluid in said MR valve to a varying magnetic field created by said coil; b) memory means in which is stored information representative of the limiting hysteresis loop relating the strength of the magnetic field in said MR valve to the current supplied to said coil; c) history determining means for determining the magnetization history of said MR valve as said current supplied to said coil varies by measuring said varying current and calculating the strength of said magnetic field created by said varying current, said strength of said magnetic field determined using said information representative of said limiting hysteresis loop stored in said memory means; d) current determining means for determining the current to be supplied to said coil that will result in a desired magnetic field using said magnetization history of said MR valve. - View Dependent Claims (17, 18, 19, 20)
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21. 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 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 current is supplied to said coil; e) at least a portion of one of said first and second members being capable of having induced therein a remanent 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; f) means for at least partially demagnetizing at least said portion of one of said first and second members in which said remanent magnetic field is capable of being induced so as to reduce said induced remanent magnetic field, said demagnetizing means comprising; (1) memory means in which is stored information representative of the limiting hysteresis loop relating the strength of the magnetic field in said MR valve to the current supplied to said coil; (2) history determining means for determining the magnetization history of said MR valve as said current supplied to said coil varies by measuring said varying current and calculating the strength of said magnetic field created by said varying current, said strength of said magnetic field determined using said information representative of said limiting hysteresis loop stored in said memory means; (3) means for determining the current to be supplied to said coil that will result in at least partially demagnetizing said portion of one of said first and second members in which said remanent magnetic field is capable of being induced without using an alternating current.
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Specification