(19)

(11)

EP 3 935 257 A1

(12)

(43) Date of publication: 12.01.2022 Bulletin 2022/02 (21) Application number: 20713073.3 (22) Date of filing: 04.03.2020

(51) International Patent Classification (IPC):  E21B 29/00(2006.01) (52) Cooperative Patent Classification (CPC): E21B 29/007; E21B 29/002 (86) International application number: PCT/GB2020/050509 (87) International publication number: WO 2020/178577 (10.09.2020 Gazette 2020/37)

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR Designated Extension States: BA ME Designated Validation States: KH MA MD TN (30) Priority: 05.03.2019 GB 201902959 (71) Applicant: Claxton Engineering Services Limited Norwich Norfolk NR1 1SW (GB)	(72) Inventors: STODDARD, John Aberdeen AB14 0UF (GB) BAXTER, Craig Castle Fraser Inverurie AB51 7LA (GB) MACWILLIAM, David Banchory AB31 4FG (GB) (74) Representative: Dummett Copp LLP  25 The Square Martlesham Heath Ipswich IP5 3SL Ipswich IP5 3SL (GB)