×

SYSTEM AND METHOD FOR DAMPING VIBRATION IN A DRILL STRING USING A MAGNETORHEOLOGICAL DAMPER

  • US 20120085581A1
  • Filed: 09/08/2011
  • Published: 04/12/2012
  • Est. Priority Date: 03/05/2009
  • Status: Active Grant
First Claim
Patent Images

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.

View all claims
  • 6 Assignments
Timeline View
Assignment View
    ×
    ×