NO20250964A1 - Fluoroelastomer compounds for sealing elements - Google Patents

Description

FLUOROELASTOMER COMPOUNDS FOR SEALING ELEMENTS

BACKGROUND

[0001] Fluoroelastomers are often used to make sealing elements and other elements in industrial applications due to their thermal resistance, chemical resistance, strength, and other material properties. The term “fluoroelastomer” is generally used to refer to synthetic rubbers that contain fluorine in its molecular structure. Fluoroelastomer materials are commonly made with monomers of vinylidene fluoride (VDF), hexafluoropropylene (HFP), perfluoromethylvinylether (PMVE), tetrafluoroethylene (TFE), propylene (P), and/or others. For example, fluoroelastic materials used in components of hydrocarbon recovery systems may include VDF-based copolymers such as Fluorine Kautschuk Material (FKM), TFE/P polymers (FEPM), and perfluoroelastomers (FFKM), to name a few.

[0002] Fluoroelastomers have been used in components of hydrocarbon recovery systems, such as in packer elements, blow out preventer elements, O-rings, gaskets, electrical insulators, pressure sealing elements for fluids, and in many other oilfield and downhole elements. In such applications, the polymers may be exposed to hostile environments, such as hostile chemical and mechanical subterranean environments, that tend to unacceptably decrease the life and reliability of the polymers. Additionally, while fluoroelastomers may provide some amount of base resistance and high-temperature resistance in sour environments (having hydrogen sulfide (H2S)), fluoroelastomer components may be one of the first to fail under high levels of dynamic stresses.

[0003] Accordingly, there remains a need for improving the reliability and life of polymeric components used in oilfield environments, such as protector bags, packer elements, pressure seals, valve seals, blow out preventer components, cable shielding and jacketing, and the like.

SUMMARY

[0004] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0005] In one aspect, embodiments disclosed herein relate to fluoroelastomer composites that are made of a fluoroelastic matrix of a fluoroelastomer and an amount of fluoro-filler material dispersed in the fluoroelastic matrix, wherein the fluoro-filler material includes a fluorinated carbon-based molecule.

[0006] In another aspect, embodiments disclosed herein relate to polymer components that are made, at least in part, of fluoroelastomer composites made of a fluoro-filler material dispersed in a fluoroelastic matrix.

[0007] Other aspects and advantages will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

[0008] The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale for purposes of clarification.

[0009] Figure 1 shows a drilling system having at least one component according to embodiments of the present disclosure.

[0010] Figure 2 shows an example of an annular blowout preventer with an annular seal according to embodiments of the present disclosure.

[0011] Figure 3 shows an example of a variable bore seal according to embodiments of the present disclosure.

[0012] Figure 4 shows an example of a packer sealing element according to embodiments of the present disclosure.

[0013] Figure 5 shows an example of an O-ring according to embodiments of the present disclosure.

[0014] Figure 6 shows an example fluoroelastomer composite according to embodiments of the present disclosure.

DETAILED DESCRIPTION

[0015] Embodiments of the present disclosure are described below in detail with reference to the accompanying figures. In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the claimed subject matter. However, it will be apparent to one having ordinary skill in the art that the embodiments described may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0016] Embodiments of the present disclosure relate generally to fluoroelastomer composites and components made therefrom. Components made from fluoroelastomer composites according to embodiments of the present disclosure may include sealing elements, such as those used in hydrocarbon recovery systems, and other components subject to harsh environments. For example, components used in hydrogen sulfide-rich environments (sour environments), such as sealing elements used in drilling operations exposed to hydrogen sulfide, may be made with fluoroelastomer composites described herein. In other embodiments, fluoroelastomer composites according to embodiments of the present disclosure may be used to make polymer components in other industries, such as in the automotive industry (e.g., for seals used in automobiles), and for hose applications.

[0017] According to embodiments of the present disclosure, fluoroelastomer composites may include fluoro-fillers dispersed in a fluoroelastic matrix. As used herein, a fluoro-filler refers to a filler material that has been modified to include fluorine (F). Examples of fluoroelastic matrix material and fluoro-fillers are described below.

[0018] Fluoroelastic Matrix

[0019] Fluoroelastic matrix materials include fluoroelastomers made of fluorinated carbon-based monomers. Examples of monomers that may be used to form a fluoroelastic matrix include, but is not limited to, ethylene (E), hexafluoropropylene (HFP), perfluoromethylvinylether (PMVE), propylene (P), tetrafluoroethylene (TFE), and vinylidene fluoride (VDF). The chemical composition (e.g., type of monomer used), fluorine content (e.g., degree of fluorination), and/or cross-linking mechanism of the fluoroelastic matrix may be varied to provide varying overall material properties.

[0020] For example, fluoroelastic matrix material used to form fluoroelastic composites for components of hydrocarbon recovery systems may include VDF-based copolymers such as fluoroelastomers classified as “FKM” under ASTM D1418 (fluoro rubbers of polymethylene type that utilizes vinylidene fluoride as a comonomer and has substituent fluoro, allyl, perfluoroalkyl or perfluoroalkoxy groups on the polymer chain), TFE/P polymers (FEPM), and perfluoroelastomers (FFKM).

[0021] FKM fluoroelastic base material may be selected from the five types classified under ASTM D1418, including, dipolymers of VDF and HFP (Type 1), terpolymers of VDF, HFP, and TFE (Type 2), terpolymers of VDF, TFE, and a fluorinated vinyl ether (Type 3), terpolymers of P, TFE, and VDF (Type 4), and pentapolymers of VDF, HFP, TFE, E, and a fluorinated vinyl ether (Type 5).

[0022] Tetrafluoroethylene propylene (FEPM, TFE/P) is a partially fluorinated polymer that is composed of both propylene and tetrafluoroethylene monomers, which can be crosslinked using a variety of curatives such as peroxides. The condensed polymer structure of FEPM is shown below.

[0023] -(CF2CF2)n-(CH2CHCH3)m-

[0024] Perfluoroelastomers (FFKM) are the elastomeric form of polytetrafluoroethylene (PTFE) and have a fluorinated backbone. As shown in the condensed polymer structure of FFKM below, FFKM includes copolymers of tetrafluoroethylene and a perfluorinated ether such as perfluoromethylvinylether (PMVE)..

[0025] -(CF2CF2)a-(CF2CFORf)b-

[0026] As shown, the backbone of FFKM includes oxygen atoms that are part of the ether groups, which provide elasticity. Depending on the type of the ether (marked by the length of the side chain), the fluorine content in FFKM may vary. To vulcanize FFKM, small amounts of a cross-linkable monomer (CSM) may be introduced, such as cyano-functional vinyl ethers.

[0027] Fluoro-fillers

[0028] According to embodiments of the present disclosure, fluoro-fillers may include a carbon-based starter filler material that has been modified to include fluorine (F). For example, carbon-based molecules such as carbon black, graphene, and carbon nanotubes may be fluorinated to have a fluorine atom compounded thereto. In one or more embodiments, starter filler material may be nano-scale carbon-based molecules, which may range in size, for example, between 1 and 500 nm in diameter.

[0029] In one or more embodiments, a starter filler material may be fluorinated by treating or reacting the starter filler material with a fluorinating agent, e.g., gaseous fluorine (F2), xenon difluoride (XeF2), hydrofluoric acid (HF), tetrafluoromethane (CF4), Terbium(IV) fluoride (TbF4), etc., using direct fluorination, indirect fluorination, or plasma-assisted fluorination methods. For example, nano-sized starter filler material may be fluorinated using direct gaseous fluorination, where the fluoro-filler is synthesized in a gas atmosphere by using F2-containing gas as a fluorinating agent. In some embodiments, fluoro-filler material may be derived from a starter filler material by replacing one or more atoms of hydrogen in the starter filler compound with fluorine.

[0030] In one or more embodiments, fluoro-filler material may be fluorinated carbon black. Fluorinated carbon black may be formed, for example, by reacting an amount of carbon black nanoparticles with gaseous fluorine (F2). The carbon black nanoparticles may be selected, for example, from N100 and N800 series. When carbon black is fluorinated, fluorine may be covalently bonded to reactive carbon atoms at the surface and subsurface shell of the carbon black particles.

[0031] In some embodiments, fluoro-filler material may be fluorographene.

Fluorographene may be formed, for example, by reacting graphene with a fluorinating agent such as xenon difluoride (XeF2), or by chemical exfoliation of graphite fluoride (CFx)n. In one or more embodiments, fluorographene may have a composition of F ranging from 53-65 weight percent (wt.%) and C ranging from 35-47 weight percent (wt.%).

[0032] In some embodiments, fluoro-filler material may be fluorinated graphene nanotubes. Fluorinated graphene nanotubes may be formed, for example, by reacting a fluorinating agent with graphene nanotube starter material under elevated temperatures (e.g., greater than 300 °F).

[0033] According to embodiments of the present disclosure, fluoro-filler material may be nanoscale in size. For example, fluoro-filler material used to form fluoroelastomer composites according to embodiments of the present disclosure may have an average particle size ranging from about 1 nm to about 500 nm. In some embodiments, fluoro-filler material may have an average particle size ranging from about 50 nm to 600 nm, or more.

[0034] Fluoroelastomer Composites

[0035] Fluoroelastomer composites according to embodiments of the present disclosure may be made, for example, by in situ polymerization, where the fluoro-filler material is mixed in a solution of fluoroelastic matrix monomers and the solution is polymerized. In some embodiments, fluoroelastomer composites may be made by direct mixing of the fluoro-filler and fluoroelastic matrix, which may include mixing a fluoroelastomer, in the absence of any solvents, with fluoro-fillers above the softening point of the fluoroelastomer or mixing the fluoroelastomer and fluoro-fillers in a solution.

[0036] As an example of forming fluoroelastomer composites according to embodiments of the present disclosure, components of a fluoroelastomer composite may be mixed in a Banbury mixer or on a roller mill. In some embodiments, components of a fluoroelastomer composite may be mixed in a slurry or solvent as a masterbatch for polymerization.

[0037] In some embodiments, one or more types of fluoro-filler material may be added to a single type of fluoroelastic matrix material to form a fluoroelastomer composite. In some embodiments, a single type of fluoro-filler material may be added to a mixture of multiple types of fluoroelastic matrix material to form a fluoroelastomer composite.

[0038] In one or more embodiments, fluoroelastomer composites may include an amount of fluoro-filler material ranging, for example, between 1 and 60 parts per hundred polymer (phr), as calculated by the weight of fluoro-filler divided by the weight of the fluoroelastomer times 100. In some embodiments, fluoroelastomer composites may include an amount of fluoro-filler material ranging between 1 and 40 phr. In one or more specific embodiments, fluoroelastomer composites may include an amount of fluoro-filler material ranging between 5 and 20 phr.

[0039] FIG. 6 shows an example fluoroelastomer composite 600 according to one or more embodiments disclosed herein. The fluoroelastomer composite 600 in FIG. 6 includes a fluoroelastic matrix 602 and a fluoro-filler 604. In one or more embodiments, the fluoroelastic matrix 602 is a fluoroelastomer 606. As described above, the fluoroelastomer 606 may be a carbon-based polymer having fluorine atoms or fluorine containing groups attached to the backbone. Additionally, the fluoro-filler 604 as described above may be a carbon based material, including carbon black, graphene, and carbon nanotubes which are functionalized with fluorine atoms. In one or more embodiments, carbon-fluorine surface bonds on the fluoro-filler 604 may improve compatibility with the fluoroelastomer 606.

[0040] Fluoro-filler 604 may be bonded to a portion of the fluoroelastomer 606 via a carbon-fluorine surface bond 612, e.g., via covalent bonding. In some embodiments, the fluoro-filler 604 may interact with the fluoroelastomer 606 through van der waals forces. In one or more embodiments, when a strain 608 is applied to the fluoroelastomer composite 600, the bonds 612 (or van der waals forces) between the fluoro-filler 604 and the fluoroelastomer 606 as shown in FIG.6 may provide an anchoring point for polymer chain extension. For example, extended fluoroelastomer chains 610 are shown after strain 608 is applied to the fluoroelastomer composite 600. The anchoring of polymer chains to the fluoro-filler 604 may therefore provide improved resistance to strain 608 and improved mechanical properties as compared to conventional fluoroelastomers.

[0041] Carbon-fluorine surface bonds of fluoro-fillers may provide enhanced polymerfiller interactions with the fluoroelastic matrix in fluoroelastomer composites according to embodiments of the present disclosure. Such enhanced polymer-filler interactions may provide improved mechanical properties over conventional fluoroelastomers, such as improved tear strength and improved fatigue resistance. The resulting improved mechanical properties allows use of fluoroelastomer composites according to embodiments of the present disclosure to withstand higher temperatures, harsher environments, and last longer in such environments when compared with conventional fluoroelastomers.

[0042] Fluoroelastomer Components

[0043] Fluoroelastomer composites according to embodiments of the present disclosure may be used to make polymer components in various industries, such as in hydrocarbon recovery systems, automotive systems, industrial processing systems, and others. For example, in the oil and gas industry, fluoroelastomer composites according to embodiments of the present disclosure may be used to form packers, annular and variable ram seals, other sealing elements used to form a seal around a pipe, gland seals, O-rings, and other pressure control sealing elements, wellsite polymer components, or downhole polymer components. In some embodiments, fluoroelastomer composites according to embodiments of the present disclosure may be used to form hoses, such as connection hoses or other fluid delivery hoses. In some embodiments, fluoroelastomer composites according to embodiments of the present disclosure may be used to form polymer components used in or around engines or other mechanical systems that may be exposed to harsh environments (e.g., high temperatures and/or corrosive elements) and dynamic conditions (e.g., sealing stresses, rotational movement, etc.).

[0044] FIGs. 1-4 show various examples of systems and components in which fluoroelastomer composites according to embodiments of the present disclosure are used to form the components. However, upon reading the present disclosure, one of ordinary skill in the art may appreciate that numerous other components may be formed of fluoroelastomer composites according to embodiments of the present disclosure.

[0045] In FIG. 1, a drilling system 100 is shown in which one or more of the polymer components are made of a fluoroelastomer composite according to embodiments of the present disclosure. The drilling system shows various equipment commonly used in drilling operations. The equipment shown is not necessarily all used simultaneously in a drilling operation but is merely included together to show their relative arrangements in a drilling system. As shown, a drilling system 100 may include a blowout preventer (BOP) 102 positioned at an opening to a well 104. A drill string 108 or other string of pipe may be inserted through the BOP 102 and into the wellbore 106, for example, to drill the wellbore 106 in a drilling operation, to produce fluids from the well in a production operation, or to perform other downhole operations.

[0046] One or more sealing elements in the BOP, such as an annular seal or a variable bore ram seal, may be made of a fluoroelastomer composite according to embodiments of the present disclosure. FIG.2 shows an example 200 of an annular seal 202 in an annular BOP 204 that is made entirely of a fluoroelastomer composite according to embodiments of the present disclosure. FIG.3 shows an example of a variable bore ram 300 having a variable ram body 302, a front seal 304 and a top seal 306, where one or both of the front seal 304 and the top seal 306 may be made entirely of a fluoroelastomer composite according to embodiments of the present disclosure.

[0047] Referring again to FIG. 1, a drilling system 100 may also include one or more packers 110 or plugs used to seal a section of the wellbore. Packers 110 and plugs may include various configurations of sealing elements which may be used, for example, to seal annular spaces in the wellbore 106 (e.g., the annular space between the drill string 108 and well wall) or to seal an entire flow path (e.g., sealing a tubing or casing bore). Examples of packers 110 and plugs that may have one or more sealing elements made of a fluoroelastomer composite according to embodiments of the present disclosure include permanent plugs, retrievable plugs, bridge plugs, inflatable packers, hydraulic packers, production packers, retrievable packers, and others. FIG.4 shows an example of a packer sealing element 400 made entirely of a fluoroelastomer composite according to embodiments of the present disclosure.

[0048] Sealing elements made entirely of a fluoroelastomer composite according to embodiments of the present disclosure may include sealing elements having a generally annular-shaped body. For example, the annular seal 202 shown in FIG. 2 and the packer sealing element 400 shown in FIG. 4 have annular shaped bodies that may be formed entirely of a fluoroelastomer composite according to embodiments of the present disclosure. Additionally, as shown in FIG.5, an O-ring 500, which has an annular-shaped body, may be formed entirely of a fluoroelastomer composite according to embodiments of the present disclosure.

[0049] Additionally, in some embodiments, polymer components may be formed of multiple polymer materials to provide different material properties to different portions of the component, where at least one of the multiple polymer materials is a fluoroelastomer composite according to embodiments described herein. For example, in some embodiments, a polymer component may be formed of two or more different fluoroelastomer composite materials according to embodiments of the present disclosure, where the different fluoroelastomer composites include a different chemical composition (e.g., type of monomer used), fluorine content (e.g., degree of fluorination), and/or crosslinking mechanism.

[0050] Fluoroelastomer composites according to embodiments of the present disclosure may be well suited for forming sealing elements and other components subject to harsh environments and/or dynamic stresses. For example, packer sealing elements 400 such as shown in FIG.4 and other downhole sealing elements may be subject to dynamic stresses such as compression forces, shear stresses, and/or torsional stresses during operation and harsh environments such as downhole pressures and temperatures (e.g., pressures greater than 5,000 psi (e.g., ranging between 10,000 psi and 35,000 psi or more) and temperatures greater than 150 °F (e.g., ranging between 170 °F and 400 °F or more)). Additionally, fluoroelastomer composites according to embodiments of the present disclosure may be particularly well suited to form components used in or exposed to sour environments with high levels of hydrogen sulfide, e.g., greater than 30 percent by volume of the environmental composition, or 40 percent by volume or more.

[0051] Although conventional fluoroelastomers have been used in many oil and gas applications to provide resistance to drilling fluids and corrosive gases like hydrogen sulfide in harsh environments, conventional fluoroelastomers suffer from lower mechanical properties such as tear strength and fatigue resistance compared with those obtainable with other oil resistant elastomer compounds used in oil and gas applications due to their mode of crosslinking. By using fluoroelastomer composites according to embodiments of the present disclosure, where reinforcing fluoro-fillers are provided in fluoroelastomer compounds, the fluoroelastomer composites may have improved mechanical properties compared to conventional fluoroelastomers, especially at higher temperatures.

[0052] While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims.

Claims (13)

C l a i m s f o r n a t i o n a l p h a s e e n t r y i n t o N o r w a y

1. A polymer, comprising:

a fluoroelastic matrix comprising a fluoroelastomer; and

an amount of fluoro-filler dispersed in the fluoroelastic matrix, wherein the fluorofiller comprises a fluorinated carbon-based molecule.

2. The polymer of claim 1, wherein the fluoroelastic matrix comprises one or more monomers selected from the group consisting of ethylene (E), hexafluoropropylene (HFP), perfluoromethylvinylether (PMVE), propylene (P), tetrafluoroethylene (TFE), and vinylidene fluoride (VDF), and wherein the polymer is synthesized by in situ polymerization of the one or more monomers of the fluoroelastic matrix and the fluorofiller.

3. The polymer of claim 1, wherein the fluoroelastic matrix is selected from Fluorine Kautschuk Material (FKM), TFE/P polymers (FEPM), and perfluoroelastomers (FFKM).

4. The polymer of claim 1, wherein the fluoro-filler is selected from at least one of fluorinated carbon black, fluorinated graphene, and fluorinated carbon nanotubes.

5. The polymer of claim 4, wherein the fluoro-filler comprises fluorinated graphene having a composition of fluorine from 53 to 65 wt.% and of carbon from 35 to 47 wt.%.

6. The polymer of claim 4, wherein the fluoro-filler comprises fluorinated carbon nanotubes formed by reacting a fluorinating agent with a graphene nanotube under temperatures of greater than 300°F.

7. The polymer of claim 1, wherein the fluoro-filler has an average particle size ranging from 1 to 500 nm.

8. The polymer of claim 1, wherein the fluoro-filler comprises a starter filler material, and wherein the starter filler material is fluorinated to produce the fluoro-filler by treating or reacting the starter filler material with one or more fluorinating agent selected from the group consisting of gaseous fluorine (F2), xenon difluoride (XeF2), hydrofluoric acid (HF), tetrafluoromethane (CF4), Terbium(IV) fluoride (TbF4).

9. The polymer of claim 1, wherein the polymer is produced by direct mixing of the fluoroelastic matrix and the fluoro-filler in absence of any solvents at a temperature above a softening point of the fluoroelastomer.

10. The polymer of claim 1, wherein the polymer is produced by direct mixing of the fluoroelastic matrix and the fluoro-filler in a solution.

11. The polymer of claim 1, wherein the polymer comprises the fluoro-filler in an amount of from 1 to 60 phr.

12. A seal, comprising:

an annular body made of a fluoroelastomer composite, the fluoroelastomer composite comprising:

a fluoroelastic matrix comprising a fluoroelastomer; and

an amount of fluoro-filler dispersed in the fluoroelastic matrix, wherein the fluoro-filler comprises a fluorinated carbon-based molecule.

13. The seal of claim 12, wherein the seal is fitted in a blowout preventer.