RU2751316C1 - Rubber mixture - Google Patents

Abstract

FIELD: rubber products.SUBSTANCE: invention relates to the field of rubber products, namely to a rubber compound for the production of water-oil-swellable rubber products based on rubbers, including water-oil-swellable packers. The rubber mixture as a base contains ethylene-propylene-diene, preferably norbornene, rubber (EPDM), hydrogenated nitrile butadiene rubber (GHNBR), spatially crosslinked polyvinylpyrrolidone (c-PVP), acrylic acid esters cross-linked by polysaccharides or their derivatives (CPAAE) and functional and technological additives.EFFECT: development of a rubber compound, from which products are made, characterized by an effective combination of swelling properties, namely, a slower volume change in oily medium with a simultaneous increased swelling in an aqueous medium.2 cl, 3 dwg, 2 tbl, 1 ex

Description

Technology area

The invention relates to the field of industrial rubber goods (RTI) and RTI for the oil industry, in particular, and can be used for the production of water-oil-swellable packers used in oil production and well development. Also, this invention can be used to create waterproofing materials in construction (between the slabs of houses), systems for protecting pipes from leaks, sealing rubbers for swimming pools, for repairing water injection equipment.

State of the art

In many applications, swellable packers or casing packers can provide a safer and easier means of separating formations than cementing and perforating. Swellable packers are widely used and give a tangible positive effect in the following operations carried out in the fields: isolation of formations, flow diversion, flow induction into the well, wells with a computerized production control system, separate production from several horizons, optimization of the use of cementing, gravel media, hydraulic fracturing , hydro and vapor barrier zones in the well, expanding check valve, well completion, etc.

The principle of operation of the swellable packer is as follows. When a swellable packer made from a special elastomer comes into contact with wellbore fluids, it swells and clogs the annulus in any open or cased hole. The absence of moving parts in the structure allows installation without the tools designed to operate the structure through the drill pipes and eliminates the possibility of failure. The elastomeric compounds from which the swellable packers are made react to borehole fluids, drilling mud, well injection fluids and are able to increase in volume relative to the volume occupied when running into the well. The use of elastomeric swellable packers in an open hole, in addition to gravel packing, insulates the lateral sections from possible water intrusion.

Long term well integrity is directly dependent on the cement sheathing of the pipeline. Failure of the cement pavement can result in lost productivity, decreased wellbore pressure, and early water production. Even a good quality cement pavement can be damaged by drilling and / or fluctuations in pressure and temperature during production. To restore it, an expensive well workover is required. Swellable packers are used to reduce the stress in the elastomer / cement contact area, thus preventing the destruction of the cement layer. When cracks form in the cement layer of the annulus, the elastomer of the swellable packer interacts with the fluids and swells and clogs their path of movement. By installing swellable packers in hazardous areas, long-term pipeline ring isolation is guaranteed.

Currently, there are many developments in this area and there are many patented developments.

So, for example, patent source WO 03008756, publication date 01/30/2003, describes a method in which a rubber cylinder is placed in the annulus of a well, which is capable of swelling on contact with water or oil, thereby cutting off the flow of water into productive formations.

Also from the patent document WO 2014062391 A1, publication date 04.24.2014, a swellable packer with a controlled swelling rate is known, which swells due to the water-absorbing additives included in the composition, namely a copolymer of tetrafluoroethylene and propylene, a grafted copolymer of starch and polyacrylate acid, a graft copolymer and a graft copolymer cyclic acid anhydride, copolymer of isobutylene and maleic anhydride, copolymer of vinyl acetate and acrylate, polymer of polyethylene oxide, grafted poly (ethylene oxide) poly (acrylic acid), polymer of carboxymethyl cellulose type, grafted copolymer of starch and acrylonitrile, polyacrylamide acrylate, polymethacrylamide , poly (2-hydroxyethyl methacrylate), poly (2-hydroxypropyl methacrylate), insoluble acrylic polymer, clay mineral with high swelling capacity, sodium bentonite, sodium bentonite with montmorillonite as the main component, calcium bentonite, their derivatives or their combination ination.

Patent document RU 2685350 C1, publication date 04/17/2019, describes a water-oil-swellable elastomeric composition based on butadiene-α-methylstyrene rubber and containing a water-swellable reagent - sodium carboxymethylcellulose in an amount of 25.0-70.0, as well as components that are customary in technology RTI.

Closest to the proposed solution is the rubber compound described in patent document RU 2686202 C1, publication date 04.24. The rubber mixture contains nitrile-butadiene rubber with a NAC content of 17-20%, butadiene rubber SKD, sevilene 11808-340, sulfur, 2,2'-dibenzthiazole disulfide, guanide F, zinc white, stearic acid, acetonanyl H, carbon black P 514, grew 175, talc, finely ground mineral powder from shungite, rosin, needle-punched cloth "Oksipan", polyacrylamide AK 639, reagent "Comet-R" and sodium salt of polyacrylic acid PAN-1.

The disadvantage of this solution is an insignificant degree of swelling in a homogeneous aqueous medium and a too high swelling rate in an environment containing oil (more than 100% in 24 hours), which can lead to emergencies during the launch and operation of equipment.

List of drawings

Figures 1-3 are graphs showing the dependence of the change in the volume of the sample on the exposure time in the medium.

Disclosure of invention

The purpose of the proposed solution is to overcome the disadvantages of the prior art and to develop a rubber compound that effectively works both in an oil-water emulsion medium and separately in water and oil environments, which is preferably used for the manufacture of packers.

The technical result of the invention consists in the development of a rubber mixture, from which products are made that have the most effective combination of swelling properties, namely, a slower volume change in oil-containing media with a simultaneous increased swelling in an aqueous medium.

When applied to packers, these improved properties have a positive effect on the safety when running the equipment, since the packer swells more slowly in an oily environment. In addition, the proposed solution has significantly improved swelling properties in the aquatic environment, which ensures the packer performance in highly watered wells. Hence, another technical result follows - versatility, since the manufactured products can be used in any types of wells or any systems where swelling of the product is required.

The technical result is achieved by providing a rubber mixture based on ethylene-propylene-diene, preferably norbornene, rubber (EPDM), and nitrile-butadiene rubber, which also contains functional additives that are traditional in the rubber industry, namely, softeners, dispersants, fillers, accelerators, curing systems, antioxidants. In this case, according to the invention, nitrile butadiene rubber is hydrogenated (GBNKS), and additional components are introduced into the mixture, namely, spatially crosslinked polyvinylpyrrolidone (c-PVP) and crosslinked polysaccharides (as well as their derivatives) acrylic acid esters (SPEAC), when the following ratio of the main components, wt. h .:

EPDM 30.0-100.0 GBNKS 30.0-100.0 c-PVP 1.0-70.0 SPEAK 1.0-70.0

The quantitative content of functional additives depends on the quantitative content of the main components and the algorithm for selecting these amounts is an operation well known to those skilled in the art.

The choice of the ratio of the main components depends on the expected operating conditions of the product made from a given rubber compound and can vary within the specified limits to achieve the required properties.

For example, can be obtained compositions of rubber mixtures with the following ratio of the main components, wt. h .:

(1) EPDM - 40.0-90.0, GBNKS - 40.0-90.0, s-PVP - 5.0-70.0, SPEAK - 5.0-70.0;

(2) EPDM - 40.0-100.0, GBNKS - 40.0-100.0, s-PVP - 5.0-60.0, SPEAK - 5.0-60.0;

(3) EPDM - 50.0-90.0, GBNKS - 50.0-90.0, s-PVP - 10.0-70.0, SPEAK - 10.0-70.0;

(4) EPDM - 40.0-80.0, GBNKS - 40.0-80.0, s-PVP - 10.0-60.0, SPEAK - 10.0-60.0;

(5) EPDM - 40.0-80.0, GBNKS - 40.0-80.0, s-PVP - 20.0-70.0, SPEAK - 20.0-70.0.

However, the quantitative ratio of the main components is not limited only to the ranges shown and may include any intermediate values included in the originally indicated ranges.

In this case, the choice of the quantitative content of c-PVP and SPEAK is due to the achievement of optimal physical and mechanical properties of the products. So, when the concentration of c-PVP and SPEAA is above 70 wt. The strength characteristics of rubbers sharply drop and the withstanding pressure likewise sharply decreases to a level unacceptable in this application, namely, for the manufacture of packers. At a concentration of c-PVP and SPEAK less than 1 wt. including the effect of the introduction of polymers is not noticeable.

In a more specific case of implementation of the invention, the composition of the rubber mixture can be presented in the following form, in wt. h .:

EPDM 30.0-100.0 GBNKS 30.0-100.0 Rosin 0.1-10.0 Zinc white 1.0-15.0 Sulfur 0.05-3.0 Organic peroxide 0.3-12.0 Covulcanization agent 0.0-6.0 Softener 1.0-30.0 Stearic acid 0.1-15.0 Excipients 0.0-70.0 Antioxidants 0.0-7.0 c-PVP 1.0-70.0 SPEAK 1.0-70.0

Ethylene propylene diene rubbers (EPDM) are synthetic elastomers. They are ternary copolymers with 1-2 mol. % diene, for example 2-ethylidene-5-norbornene, dicyclopentadiene. They dissolve in many hydrocarbons and their chlorine derivatives. EPDM is obtained by copolymerizing ethylene with propylene and diene on a Ziegler-Natta catalyst in a solution or excess of polypropylene. Unplasticized. Vulcanized with sulfur, phenol-formaldehyde resins. EPDMs have excellent weather and ozone resistance, high thermal, oil and wear resistance, but also high air permeability, resistant to aggressive environments, have good dielectric properties; tensile strength 20-28 MPa, elongation 400-600%, rebound elasticity 40-52%.

Hydrogenated nitrile butadiene rubber (NBRB), i.e. hydrogenated (cross-linked with peroxide), belongs to the family of nitrile rubbers and, as the name suggests, is obtained by partial or complete hydrogenation (hydrogenation) of nitrile butadiene rubber (NBR). The resulting rubber significantly outperforms BNC in durability and mechanical properties, while maintaining a relatively low cost.

The properties of HBNS depend on the content of acrylonitrile and residual double bonds: with an increase in the content of acrylonitrile, the resistance to temperature and oil products increases, but the properties deteriorate at low temperatures. GBNKS exhibits resistance to low and better resistance to high temperatures, and, depending on the brand, has an operating range from -45 to + 165 ° C. HBNKS shows good resistance to ozone, weathering and aging, and is also resistant to hot water and steam up to 150 ° C. HBNKS exhibits good abrasion resistance. GBNKS is resistant to aliphatic hydrocarbons (propane, butane, oil, diesel fuel, fuel oil), vegetable and mineral oils and greases, non-flammable hydraulic fluids (HFA, HFB and HFC). Also resistant to dilute acids, alkalis and salt solutions at medium temperatures. HBNKS shows some resistance to fuels with a high (up to 40%) content of aromatic hydrocarbons. Certain brands of HBNKS with a high acrylonitrile content are also resistant to biofuels and oxygen-containing fuels.

Spatially crosslinked polyvinylpyrrolidone (c-PVP) is a cross-linked version of polyvinylpyrrolidone (PVP), a polymer of N-vinylpyrrolidone. This property renders polyvinylpyrrolidone insoluble in water. However, this substance still absorbs water and swells very quickly, which creates a swelling force. The melting point of c-PVP is about 165 ° C. It can be obtained, for example, by radical copolymerization of N-vinylpyrrolidone in the presence of a crosslinking agent.

Acrylic acid esters crosslinked with polysaccharides (SPEA) are obtained by free radical copolymerization of polysaccharides and acrylic acid esters. The source of radicals can be peroxides, persulfates, or radicals can be formed under the influence of ionizing radiation, ultraviolet waves, high temperatures and other methods used in the radical polymerization of polymers. The features of SPEAK include high molecular weight, electrical conductivity, biological inertness, and a significant degree of swelling in water (up to 20-30 times). As polysaccharides used for the preparation of SPEAK, there can be used, for example, chitosan, cellulose, alginate, sucrose and erythrol, as well as derivatives of these compounds, for example, alkyl- and aryl-substituted.

Functional additives used in the invention such as softeners, dispersants, fillers, accelerators, vulcanizing systems, antioxidants and the like. are well known to those skilled in the art and do not require special disclosure. Suitable additives are disclosed, in particular, in the book "Functional Fillers for Plastics" ed. Marino Xanthos, 2010

As for the mechanism for achieving the technical result, this issue has not been fully investigated by us, however, the increased swelling capacity of the proposed rubber compound is most likely associated with the nature of the polymers c-PVP and SPEAK themselves, since the backbone of each polymer contains a sufficient number of polar atoms (eg oxygen) that can form hydrogen bonds, thereby causing swelling. Also, it is believed that there is a synergy from the combined use of c-PVP and SPEAC, expressed in increased swelling when these two ingredients are used together. This effect is most likely associated with the formation of a spatial network by them (in properties, resembling a percolation network of a filler), and / or the formation of physical bonds between polar groups.

It should also be noted that the manufacture of water-oil-swellable packers is not the only area of application of the proposed rubber compound and it can be used in any field requiring the use of materials with water-, oil- or oil-swelling properties. In particular, this invention can be used to create waterproofing materials in construction (between slabs of houses), systems for protecting pipes from leaks, sealing rubbers for swimming pools, for repairing water injection equipment, etc.

Implementation of the invention

To confirm the possibility of carrying out the invention and achieving the technical result, a number of studies and experiments were carried out. The experimental results are presented below.

The rubber mixture was made on laboratory rolls LB 320 150/150 (manufactured by Krasin Plant JSC) with a total load of 1200 g.

The components of the rubber mixture were synthetic ethylene-propylene-norbornene rubber (Vistalon from ExxonMobil), hydrogenated nitrile butadiene rubber (Therban from Arlanxeo), pine rosin (GOST 19113), zinc oxide (GOST 208-84), sulfur (Polsinex Grupa Azoty), di (tert-butylperoxyisopropyl) benzene (40%) on an inert carrier (Perkadox 14-40 by Nouryon), dibutyl phthalate (GOST 8728-88), stearic acid (GOST 6484-84), c-PVP (Sigma Aldrich), SPEAK (Supelco).

The ratios of the components of the proposed solution and the prototype are shown in Table 1:

Table 1

Compositions of rubber compounds

Proposed solution Prototype BNKS - 15.00 GBNKS 30,00 - SKI-3 - 40,00 SKD - 45.00 EPDM 70,00 - Sulfur 0.20 1.50 N, N'-dithiomorpholine - 1.50 Guanidin F - 1.20 Sulfenamide C - - Zinc oxide 5.00 3.50 Stearic acid 5.00 2.00 Acetanonyl H - 0.50 Dibutyl phthalate 9.50 - TU P514 - 9.50 Rosil 175 - 9.50 Talc - 9.50 Shungite - 9.50 Rosin 3.00 5.50 Needle-punched cloth "Oksipan" - 4.50 Polyacrylamide AK 639 - 5.50 Reagent "Comet-R" - 9.50 Sodium salt of polyacrylic acid PAN-1 - 9.50 Organic peroxide 3.00 - c-PVP 30,00 - SPEAK 50,00 -

Samples were covulcanized from the rubber compounds produced on an LP 600kN vulcanization press (f. Montech). After 24 hours curing, the samples were tested in accordance with GOST ISO 1817-2016 “Rubber and thermoplastic elastomers. Determination of resistance to liquids ". The liquids used were: water with a salinity of 50 g / l, oil and a mixture of water and oil (1: 1). The test results are shown in Table 2.

table 2

Test results

Proposed solution prototype Tests in mineralized water (50 g / l) Volume change after 12 hours,% thirty 42 Volume change after 24 hours,% 54 46 Volume change after 48 hours,% 72 47 Volume change after 72 hours,% 81 47 Volume change after 96 hours,% 100 47 Volume change after 120 hours,% 117 48 Volume change after 144 hours,% 136 48 Volume change after 168 h,% 157 48 Volume change after 336 h,% 253 52 Volume change after 504 hours,% 307 64 Testing in oil Volume change after 12 hours,% 32 97 Volume change after 24 hours,% 48 119 Volume change after 48 hours,% 72 136 Volume change after 72 hours,% 110 164 Volume change after 96 hours,% 142 187 Volume change after 120 hours,% 182 201 Volume change after 144 hours,% 205 217 Volume change after 168 h,% 231 242 Volume change after 336 h,% 320 263 Volume change after 504 hours,% 362 271 Tests in a mixture of water: oil (1: 1) Volume change after 12 hours,% 39 119 Volume change after 24 hours,% 58 145 Volume change after 48 hours,% 89 169 Volume change after 72 hours,% 134 203 Volume change after 96 hours,% 177 230 Volume change after 120 hours,% 221 242 Volume change after 144 hours,% 249 266 Volume change after 168 h,% 281 296 Volume change after 336 h,% 393 326 Volume change after 504 hours,% 438 335

For ease of understanding and clarity, the test results were plotted graphs (Fig. 1, Fig. 2, Fig. 3).

According to the test results, it can be seen that the change in volume in oily media for the proposed solution is slower, which favorably affects the safety when lowering the equipment. In addition, the proposed solution significantly surpasses the prototype in terms of swelling in an aqueous medium, which ensures its operability in conditions of heavily flooded wells.

Similar tests were carried out with other quantitative ratios of components, which showed an improvement in properties compared to the prototype over the entire stated range of values.

Claims (5)

1. Rubber compound for the manufacture of water-oil-swellable rubber products based on rubbers, characterized in that it contains ethylene-propylene-diene rubber (EPDM), hydrogenated nitrile butadiene rubber (GBNCS), spatially cross-linked with polyvinylpyrrolidone (c-PVP) and crosslinked their derivatives of acrylic acid esters (SPEAC), and also contains functional and technological additives, including softeners, dispersants, vulcanizing system, and may additionally contain antioxidants, fillers, accelerators and rosin, with the following ratio of polymer components, mass parts: EPDM 30.0-100.0 GBNKS 30.0-100.0 c-PVP 1.0-70.0 SPEAK 1.0-70.0 2. The rubber mixture according to claim 1, characterized in that the rubber product is a packer. 3. A rubber mixture according to claim 1 or 2, characterized in that it has the following composition, parts by weight: EPDM (norbornene) 30.0-100.0 GBNKS 30.0-100.0 Rosin 0.1-10.0 Zinc white 1.0-15.0 Sulfur 0.05-3.0 Organic peroxide 0.3-12.0 Covulcanization agent 0.0-6.0 Softener 1.0-30.0 Stearic acid 0.1-15.0 Excipients 0.0-70.0 Antioxidants 0.0-7.0 c-PVP 1.0-70.0 SPEAK 1.0-70.0

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