US 11,840,900 B2
Well abandonment and slot recovery
Hans Christian Karlsen, Trondheim (NO); Eskild Storteig, Rognan (NO); Alagappan Vishwanathan, Aberdeen (GB); Michael Wardley, Aberdeen (GB); and James Linklater, Aberdeen (GB)
Assigned to ARDYNE HOLDINGS LIMITED, Aberdeen (GB)
Appl. No. 17/427,790
Filed by ARDYNE HOLDINGS LIMITED, Aberdeen (GB)
PCT Filed Feb. 13, 2020, PCT No. PCT/EP2020/053809
§ 371(c)(1), (2) Date Aug. 2, 2021,
PCT Pub. No. WO2020/165369, PCT Pub. Date Aug. 20, 2020.
Claims priority of application No. 1902058 (GB), filed on Feb. 14, 2019; and application No. 1912225 (GB), filed on Aug. 26, 2019.
Prior Publication US 2022/0127922 A1, Apr. 28, 2022
Int. Cl. E21B 31/00 (2006.01); E21B 28/00 (2006.01); E21B 31/113 (2006.01); E21B 31/20 (2006.01)
CPC E21B 31/005 (2013.01) [E21B 28/00 (2013.01); E21B 31/113 (2013.01); E21B 31/20 (2013.01)] 25 Claims
OG exemplary drawing
 
1. A vibratory casing recovery assembly, comprising:
a bottom hole assembly (BHA), configured to be suspended from an anchor mechanism on a fluid carrying string, the BHA comprising:
a flow modifier for producing cyclic variations at a first frequency in the pressure of fluid through the string, and
a dynamic amplification tool adapted to cause axial movement in the bottom hole assembly in response to variations in the flow of fluid through the string;
the dynamic amplification tool being arranged between the anchor mechanism and the flow modifier; and
the dynamic amplification tool being configured to provide a natural resonant frequency in the bottom hole assembly wherein:
0.6<first frequency/natural frequency<1.2
to provide a dynamic amplification factor of >1.