US 12,091,958 B2
Drilling system control for reducing stick-slip by calculating and reducing energy of upgoing rotational waves in a drillstring
Benjamin Peter Jeffryes, Cambridge (GB)
Assigned to SCHLUMBERGER TECHNOLOGY CORPORATION, Sugar Land, TX (US)
Filed by SCHLUMBERGER TECHNOLOGY CORPORATION, Sugar Land, TX (US)
Filed on Jan. 18, 2021, as Appl. No. 17/151,286.
Application 17/151,286 is a continuation of application No. 14/778,626, granted, now 10,927,658, previously published as PCT/IB2014/059978, filed on Mar. 19, 2014.
Claims priority of provisional application 61/803,686, filed on Mar. 20, 2013.
Prior Publication US 2021/0189857 A1, Jun. 24, 2021
Int. Cl. E21B 44/02 (2006.01); E21B 3/02 (2006.01); E21B 44/00 (2006.01); G05B 19/401 (2006.01)
CPC E21B 44/02 (2013.01) [E21B 3/022 (2020.05); E21B 44/00 (2013.01); G05B 19/401 (2013.01); G05B 2219/45129 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A drilling system comprising:
a drillstring;
a drill bit coupled to the drillstring;
a drive system configured to rotate the drillstring to drill a borehole through an earth formation in a manner that reduces stick-slip;
one or more sensors configured to measure properties of the drilling system; and
a controller configured to:
receive a desired rotation speed v0 of the drive system to rotate the drillstring;
receive the property measurements of the drilling system and deriving therefrom a rotation speed vup of upgoing rotational waves of the drillstring associated with upgoing rotational energy in the drillstring, wherein vup is derived from surface measured properties comprising: rotational speed of the drillstring and a torque T in the drillstring;
determine an actual rotation speed v of the drive system to rotate the drillstring by:
representing energy in the drillstring as a mathematical expression comprising a sum of rotational energy produced by the drive system and downgoing rotational energy caused by the upgoing rotational waves that are reflected at an upper end of the drillstring into downgoing rotational waves, wherein the rotational energy produced by the drive system is a function of v and v0, and wherein the downgoing rotational energy caused by the upgoing rotational waves is a function of v and vup; and
optimizing the mathematical expression, the optimized mathematical expression expressing v in terms of v0 and vup; and
control the drive system to rotate the drillstring at v.