US 11,840,899 B2
Well abandonment and slot recovery
Hans Christian Karlsen, Trondheim (NO); Eskild Storteig, Rognan (NO); Steffen Hansen, Aberdeen (GB); Michael Wardley, Aberdeen (GB); and James Linklater, Aberdeen (GB)
Assigned to ARDYNE HOLDINGS LIMITED, Aberdeen (GB)
Appl. No. 17/427,703
Filed by Ardyne Holdings Limited, Aberdeen (GB)
PCT Filed Feb. 13, 2020, PCT No. PCT/EP2020/053796
§ 371(c)(1), (2) Date Aug. 2, 2021,
PCT Pub. No. WO2020/165364, PCT Pub. Date Aug. 20, 2020.
Claims priority of application No. 1902058 (GB), filed on Feb. 14, 2019.
Prior Publication US 2022/0145718 A1, May 12, 2022
Int. Cl. E21B 31/00 (2006.01); E21B 28/00 (2006.01); E21B 31/20 (2006.01)
CPC E21B 31/005 (2013.01) [E21B 28/00 (2013.01); E21B 31/20 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method of casing recovery in a wellbore, comprising the steps;
(a) running a string into the wellbore, the string including a vibratory casing recovery bottom hole assembly, the vibratory casing recovery bottom hole assembly comprising:
a casing spear having a gripping mechanism to anchor the spear to casing to be recovered;
a flow modifier for producing cyclic variations at a first frequency in the flow of fluid through the string, and
one or more elements, the one or more elements including an extension and retraction means for location in the string and adapted to axially extend or contract in response to variations in the flow of fluid through the string; and
the extension and retraction means being arranged between the casing spear and the flow modifier within the casing to be recovered;
(b) anchoring the casing spear to the casing to be recovered by use of the gripping mechanism;
(c) pumping fluid from surface through the string to produce cyclic variations at the first frequency in the flow of fluid through the string to induce vibration in and axially extend and contract the extension and retraction means;
(d) pulling the string and the vibratory casing recovery bottom hole assembly to recover the casing to be removed;
characterised in that:
at least one element is configured to have a resonant frequency in the assembly when vibrated wherein:
0.6<first frequency/resonant frequency<1.2.