Packer cup and method for manufacturing same

Abstract

The invention relates to the oil industry, and more particularly to the recovery of oil from wells, and can be used as sealing elements for packers designed to hermetically seal well casing intervals during various well operations. A packer cup is proposed which is in the form of a flared sleeve with a stepped through-hole. The sleeve is made in one piece from a material having a Shore hardness of A 90±5, a tensile strength of not less than 5 MPa, an elongation at break of not less than 30%, and a modulus of compression of not less than 150 MPa. Methods for manufacturing such a cup are proposed. The technical result to be achieved using the proposed invention is that of increasing the operating reliability and lifetime of a packer, improving manufacturability, and rendering the packer cup less labour-intensive to manufacture by using material that has specific properties and by virtue of the design.

Description

[0001] PACKER'S CUP CUFF AND ITS MANUFACTURING METHOD

[0002] The invention relates to the oil industry, in particular to the extraction of oil from wells, and can be used as sealing elements for packers intended for the hermetic isolation of intervals of a casing string during the course of various technological operations at a well.

[0003] Packer cuffs are known according to patents RU81249 (IPC E21B 33 / 12, published 10.03.09) and RU195714 (IPC E21B 33 / 12, published 04.02.20), US20030098153 (IPC E21B 33 / 12, published 29.05.03), having a fundamentally similar design, containing an elastic element made in the form of a trapezoidal ring of longitudinal axial section, reinforced with metal elements with a sleeve.

[0004] The disadvantage of these solutions is the relatively high labor intensity of cuff production, associated with the need to manufacture reinforcing elements and position them in the mold before vulcanization of the rubber mixture, the use of reinforcing elements leads to uncontrolled radial deformation of the bearing part of the cuff and its wear, exposing the reinforcement, which in this case can break off. The main problem in the use of reinforcement is that after the first operation, the reinforcement does not allow the cuff to return to its original state, thereby maintaining the interaction between the cuff and the casing. Further movement of the cuff along the column contributes to abrasive wear of the thin layer of rubber on the surface of the reinforcement, which with a high probability leads to the destruction of the internal rubber layer of the cuff and, as a result, the latter's non-hermeticity.To solve this problem, to protect the inner rubber surface of the cuff, it is necessary to use reinforcement with two rows of petals, which worsens the manufacturing technology of such cuffs. Damage to the cuff is shown in Fig. 1. Also known is a packer cuff, which is made in the form of a sleeve having an intermediate part and two end parts. The intermediate part is made of an elastic material with a strength of 15+40 MPa and a hardness of 60+80 units according to Shore. The end parts are made of an elastic material and reinforced with a metal element made of turns of steel wire with a bulk density of 70+90%, which allows having a hardness of 90+100 units according to Shore. The steel wire has a tensile strength of 290+350 N / mm. 2, and the relative elongation is 5+12%. The longitudinal axial section of each end part has the shape of a truncated rectangular trapezoid, inside which there are turns of steel wire with a bulk density of 70+90% (according to patent RU 164011, IPC E21B 33 / 12, published 20.08.16).

[0005] The disadvantage of this solution is the relatively high labor intensity of cuff production, associated with the need to manufacture reinforcing elements and position them in the mold before vulcanization of the rubber mixture.

[0006] A cup packer cuff is known for sealing the inside of a pipe under pressure. The cuff is made in the form of a bell. The wide end has a lip made of a softer material, which is an integral part of the cuff body, which is a harder material (according to patent US7261153B2, IPC E21B 33 / 12, published 28.08.07).

[0007] A known cup-shaped packer cuff for sealing the inside of a pipe under pressure includes a first portion of a relatively soft material and a second portion of a relatively hard material. The portion of the relatively softer material begins at the edge of the cuff and extends from the outside by one third of the length to the entire length of the cuff. The cuff may additionally contain a bushing or retainer fixed in a hard material for fastening to a packer (according to patent US7959155B2, IPC E21B 33 / 126, published 14.06.11). The disadvantage of these cuffs is that the hard material provides rigidity of the cuff, but limits its opening under pressure and pressing against the walls of the casing pipe, and the sealing of the cuff is ensured by elastic compression of the soft material. As a result, the tightness of the cuff may be insufficient, especially in the presence of defects on the inner wall of the casing pipe.

[0008] The closest technical solution is a cup packer cuff, which, according to the design variant, consists of a housing with a longitudinal hole. The outer part of the housing and the hole expand in the longitudinal direction from one end to the other. The housing is made of an elastomer selected from the group of butadiene-nitrile and hydrogenated butadiene-nitrile rubbers with a surface hardness of 80 to 90 Shore A (according to patent US6668938B2, IPC E21B 33 / 128, published 30.12.03).

[0009] This solution specifies only the material and its hardness, while other properties of the material used are also important for efficient operation, such as strength and tensile strength, elastic modulus. Various materials can be used to ensure these properties.

[0010] The technical result achieved by using the proposed invention consists in increasing the reliability of the operation and service life of the packer, as well as increasing the manufacturability and reducing the labor intensity of manufacturing the packer cuff due to the use of a material with certain properties and design.

[0011] The technical result of the invention is achieved in that the cup-shaped cuff of the packer is made in the form of an expanding sleeve with a through stepped hole and is distinguished by the fact that the sleeve is made of a single piece of material having a Shore A hardness of 90±5, a tensile strength of at least 5 MPa, an elongation at break of at least 30% and a modulus of elasticity under compression of at least 150 MPa. In addition, the cuff material may contain the following components mixed in the following proportion in mass fractions:

[0012] - shungite powder with particle size of 1...20 µm - from 90 to 110;

[0013] - elastomer binder grade BKNS made of butadiene-nitrile rubber - from 25 to 35;

[0014] - cross-linking agent in the form of organic peroxide - from 1 to 2;

[0015] - mineral fibers - from 1 to 30.

[0016] The cup packer cuff is manufactured by a method that involves forming a blank from a mixed mass in a molding cavity of a press mold and is distinguished by the fact that the mixed mass for the blank is mixed on laboratory rollers until a homogeneous mass is obtained from the following components, mixed in the following proportion in mass fractions:

[0017] - shungite powder with particle size of 1...20 µm - from 90 to 110;

[0018] - elastomer binder grade BKNS made of butadiene-nitrile rubber - from 25 to 35;

[0019] - cross-linking agent in the form of organic peroxide - from 1 to 2;

[0020] - mineral fibers - from 1 to 30 then a blank is made from the mixed mass, the volume of which corresponds to the volume of the molding cavity of the press mold, the blank is placed in the press mold and vulcanized, after vulcanization the resulting cuff is kept in a free state for at least 4 hours.

[0021] The preferred mixing time of the mixture mass is 30±5 minutes with a friction of 1:1.25.

[0022] Vulcanization is preferably carried out at a temperature of 160 to 180 °C for 10 to 40 minutes.

[0023] The proposed invention is illustrated by the following drawings:

[0024] Fig. 2 - packer cuff, axonometry;

[0025] Fig. 3 - packer cuff, longitudinal section; Fig. 4 - packer.

[0026] The cup-shaped cuff of the packer 1 (Fig. 2, 3) is made in the form of an expanding sleeve 2 with a through stepped hole 3.

[0027] The cup packer cuff is manufactured in the following way. The following components are used to create a carbon-carbon matrix (CC):

[0028] - shungite powder with particle size of 1...20 µm - from 90 to 110;

[0029] - elastomer binder grade BKNS made of butadiene-nitrile rubber - from 25 to 35;

[0030] - cross-linking agent in the form of organic peroxide - from 1 to 2;

[0031] - mineral fibers - from 1 to 30.

[0032] The mixing of the above components is carried out on laboratory rollers PD 320 160 / 160 with friction 1:1.25, for 30±5 min until a homogeneous mixture is obtained. A blank corresponding to the volume of the molding cavity of the press mold is made from the mixture.

[0033] The blank is vulcanized in the mold nest using mold technology for the production of an elastomer product at a temperature of 160 to 180 °C and a process duration of 10 to 40 minutes. The vulcanized blank made from the prepared elastomer mixture has an elongation of 50-140% at break and a strength of at least 5 MPa. After vulcanization, the blank is kept in a free state for 4 hours to relieve stress.

[0034] The cup cuff manufactured using the described method has the following characteristics: Shore A hardness of 90±5, tensile strength of at least 5 MPa, elongation at break of at least 30% and a modulus of elasticity under compression of at least 150 MPa.

[0035] Application.

[0036] A cup-shaped cuff is used as part of a packer that is mounted on a production string. For example, as part of a cup-shaped packer used in hydraulic fracturing. The packer (Fig. 4) consists of a body 4 with an upper sleeve 5 and a lower sleeve 6 screwed onto it. Cup-shaped cuffs 1 are installed between sleeves 5 and 6. A protective sleeve 7 is installed on the narrow side of each cuff 1. The cuffs 1 are pressed by adjusting sleeves 8 and a pressure ring 9.

[0037] After the packer is installed on the column, it is lowered into the well. During the lowering process, the cup cuffs are pressed against the packer body and do not impede movement during the lowering process.

[0038] After the packer has been installed in the specified interval, it can be used for its intended purpose. The well zones are separated by opening the cup cuffs under pressure in such a way as to ensure tight contact of the cuff edges with the well walls.

[0039] If it is necessary to change the interval of the packer placement by lifting or lowering, the cup cuffs are pressed against the packer body after the pressure is released, and the placement is changed, after which the cuffs open again at the specified point, ensuring the separation of the well zones in accordance with the functional purpose.

[0040] The manufacture of a cuff from a material having the characteristics according to the proposed invention allows for increased operational reliability and service life due to:

[0041] - increased wear resistance of the cuff during lifting and lowering operations (Shore A hardness 90±5);

[0042] - ability to withstand high pressure up to 70 MPa (tensile strength not less than 5 MPa)

[0043] - the necessary elasticity to ensure the opening of the cuff during packer operation (tensile strength at break of at least 30%, modulus of elasticity under compression of at least 150 MPa). The specified properties can be obtained in a material whose composition and manufacturing method are described in the proposed invention.

[0044] The specified properties make it possible to avoid using metal reinforcement in the cuff design, located in the cuff body, which leads to damage to the polymer material of the cuff during repeated use, and also significantly increase manufacturability and reduce the labor intensity of manufacturing, since there is no need to manufacture metal parts and install and position them in the mold.

[0045] Thus, the solutions used in the invention make it possible to increase the reliability of the packer's operation and service life, as well as to improve the manufacturability and reduce the labor intensity of manufacturing the cuff, thereby contributing to the achievement of the technical result.

Claims

CLAUSE OF INVENTION 1. A packer cup seal made in the form of an expanding sleeve with a through stepped hole, characterized in that the sleeve is made in one piece from a material having a Shore A hardness of 90±5, a tensile strength of at least 5 MPa, an elongation at break of at least 30% and a modulus of elasticity under compression of at least 150 MPa, and the material of the seal contains the following components mixed in the following proportion in mass fractions: - shungite powder with particle size of 1...20 µm - from 90 to 110; - elastomer binder grade BKNS made of butadiene-nitrile rubber - from 25 to 35; - cross-linking agent in the form of organic peroxide - from 1 to 2; - mineral fibers - from 1 to 30.

2. A method for manufacturing a packer cup seal, which consists of forming a blank from a mixed mass in a molding cavity of a press mold and is characterized in that the mixed mass for the blank is mixed on laboratory rollers until a homogeneous mass is obtained from the following components, mixed in the following proportion in mass fractions: - shungite powder with particle size of 1...20 µm - from 90 to 110; - elastomer binder grade BKNS made of butadiene-nitrile rubber - from 25 to 35; - cross-linking agent in the form of organic peroxide - from 1 to 2; - mineral fibers - from 1 to 30; then a blank is made from the mixed mass, the volume of which corresponds to the volume of the molding cavity of the press mold, the blank is placed in the press mold and vulcanized, after vulcanization the resulting cuff is kept in a free state for at least 4 hours.

3. The method according to item 2, characterized in that the mixing time of the mixture mass is 30±5 minutes with a friction of 1:1.

25.

4. The method according to paragraph 2 or 3, characterized in that vulcanization is carried out at a temperature of 160 to 180 °C for 10 to 40 minutes.

Images