US 12,188,335 B2
Method of increasing well bottomhole resistance to destruction
Aleksandr Mikhajlovich Svalov, Moscow (RU)
Assigned to PUBLICHNOE AKTSIONERNOE OBSCHESTVO “GAZPROM”, Saint-Petersburg (RU)
Appl. No. 17/610,385
Filed by PUBLICHNOE AKTSIONERNOE OBSCHESTVO “GAZPROM”, Saint-Petersburg (RU)
PCT Filed Jul. 27, 2020, PCT No. PCT/RU2020/000393
§ 371(c)(1), (2) Date Nov. 10, 2021,
PCT Pub. No. WO2021/025590, PCT Pub. Date Feb. 11, 2021.
Claims priority of application No. RU2019124673 (RU), filed on Aug. 2, 2019.
Prior Publication US 2022/0259951 A1, Aug. 18, 2022
Int. Cl. E21B 7/28 (2006.01); E21B 7/20 (2006.01); E21B 43/02 (2006.01); E21B 43/12 (2006.01)
CPC E21B 43/02 (2013.01) [E21B 7/28 (2013.01); E21B 43/12 (2013.01); E21B 7/20 (2013.01)] 2 Claims
OG exemplary drawing
 
1. A method of improvement of well bottom zone resistance to decay, comprising:
boring of a well passing through an impermeable rock formation into a producing rock formation, wherein a zone of contact is formed between the impermeable rock formation and the producing rock formation;
forming, by jet-breaking, a tapered cavern having a top directed towards a formation inner part, the tapered cavern positioned within the zone of contact between the impermeable rock formation and the producing formation;
running a casing into the well in order to form a borehole annulus between an outer wall of the casing and a wall of the well, and
cementation of the borehole annulus and the tapered cavern so that the tapered cavern is completely filled with cement, the tapered cavern positioned so that a shear stress at a contact surface between the impermeable rock formation and the producing rock formation is spread away from the casing in order to increase a resistance of a well bottom zone to decay,
wherein the tapered cavern parameters meet the requirements of:
Rc−R−δ≥4 cm,
5°≤α≤30°,
where Rc is the radius of the cavern measured from the well axis along the contact surface between the impermeable rock formation and the producing rock formation, cm;
R is the well radius measured from the well axis to the casing inner surface, cm;
δ is casing wall thickness, cm;
α is the angle between the cavern and casing generatrices, deg.