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(11)

EP 3 423 665 A1

(12)

(43) Date of publication: 09.01.2019 Bulletin 2019/02 (21) Application number: 17838028.3 (22) Date of filing: 06.12.2017

(51) International Patent Classification (IPC):  E21B 4/02(2006.01) E21B 7/06(2006.01) E21B 7/04(2006.01) (86) International application number: PCT/BG2017/000029 (87) International publication number: WO 2018/157218 (07.09.2018 Gazette 2018/36)

(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: MA MD TN (30) Priority: 28.02.2017 BG 11247017 (71) Applicants: Lyomov, Shteryo Kostadinov 1271 Sofia (BG) Topev, Grigor Ivanov 1309 Sofia (BG)	(72) Inventors: Lyomov, Shteryo Kostadinov 1271 Sofia (BG) Topev, Grigor Ivanov 1309 Sofia (BG) (74) Representative: Pakidanska, Ivanka Slavcheva  6, Trapezica street, fl.1 1000 Sofia 1000 Sofia (BG)