SWELLABLE ARTICLE

[0001] Fluid-swellable and fluid-absorbent materials are used in a variety of industries. For example, in the downhole drilling and completions industry, swellable materials are used for a variety of packer, isolation, actuation, and sealing devices that react automatically upon exposure to particular downhole fluids, such as oil and water. While these swellable materials are used satisfactorily for various purposes, the art nevertheless always well receives advances and alternatives to swellable and absorbent material systems.

[0002] A swellable article, including a matrix material; and an exfoliatable graphene-based material disposed in the matrix material, wherein the exfoliatable graphene-based material is operatively arranged to facilitate swelling of the swellable article upon exposure to a selected fluid by sorbing particles in the fluid, the swelling enabling the swellable article to engage an adjacent structure.

[0003] A method of using a swellable article including exposing a swellable article according to the above to a selected fluid; swelling the swellable article with the selected fluid; sorbing particles in the fluid with the graphene-based material in order to facilitate the swelling; and engaging the swellable article with an adjacent structure after swelling.

[0004] A method of making a swellable article including disposing a graphene-based material in a matrix material to yield a swellable material; exfoliating the graphene-based material; and forming the swellable material into an article that is swellably responsive to a selected fluid, the graphene-based material operatively arranged to facilitate swelling of the swellable article upon exposure to a selected fluid by sorbing particles in the fluid.

[0008] A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

[0009] Referring now to the drawings, a process for making and using a swellable article 10 is shown schematically in FIG. 1. The process to ultimately form the article 10 begins by creating an exfoliatable graphene-based material compound 12. By graphene-based material it is meant graphene, graphite, graphene oxide, graphite oxide, graphite intercalation compounds and their derivatized forms to include a functional group, e.g., including carboxy, epoxy, ether, ketone, amine, hydroxy, alkoxy, alkyl, aryl, aralkyl, alkaryl, lactone, functionalized polymeric or oligomeric groups, or a combination comprising at least one of the forgoing functional groups. Graphite intercalation compounds can include intercalating agents such as, for example, an acid, metal, binary alloy of an alkali metal with mercury or thallium, binary compound of an alkali metal with a Group V element (e.g., P, As, Sb, and Bi), metal chalcogenide (including metal oxides such as, for example, chromium trioxide, PbO₂, MnO₂, metal sulfides, and metal selenides), metal peroxide, metal hyperoxide, metal hydride, metal hydroxide, metals coordinated by nitrogenous compounds, aromatic hydrocarbons (benzene, toluene), aliphatic hydrocarbons (methane, ethane, ethylene, acetylene, n-hexane) and their oxygen derivatives, halogen, fluoride, metal halide, nitrogenous compound, inorganic compound (e.g., trithiazyl trichloride, thionyl chloride), organometallic compound, oxidizing compound (e.g., peroxide, permanganate ion, chlorite ion, chlorate ion, perchlorate ion, hypochlorite ion, As₂O₅, N₂O₅, CH₃ClO₄, (NH₄)₂S₂O₈, chromate ion, dichromate ion), solvent, or a combination comprising at least one of the foregoing. Exemplary acids include nitric acid, sulfuric acid, acetic acid, CF₃COOH, HSO₃F, HSO₃Cl, HSO₃CF₃, persulfuric acid (e.g., H₂SO₅, H₂S₂O₈), phosphoric acid, H₄P₂O₇, perchloric acid, H₃AsO₄, H₂SeO₄, HIO₄, H₅IO₆, HAuCl₄, H₂PtCl₆, or a combination comprising at least one of the foregoing. Exemplary metals include alkali metals (e.g., lithium, sodium, potassium, and the like), alkaline earth metals (e.g., magnesium, calcium, strontium, and the like), rare earth metals (e.g., scandium, yttrium, lanthanide elements, and the like), transition metals (e.g., iron, tungsten, vanadium, nickel, and the like), and post-transition metals (e.g., aluminum, tin, and the like). Exemplary metal halides include NaI, FeCl₃, CuCl₂, AuCl₃, MoCl₅, SbCl₅, and the like. Nitrogenous compounds include, for example, ammonia, ammonium, hydrazines, amines, and amides. Exemplary halogens include Cl₂, Br₂, BrCl, ICl, IBr, BrF₃,BrF₅, and IF₅. Exemplary fluorides include halogen fluorides, boron fluoride, hydrogen fluoride, PF₅, AsF₅, and rare gas fluoride. Exemplary solvents include benzene, toluene, o-xylene, dimethyl sulfoxide, furan, tetrahydrofuran, o-dioxane, m-dioxane, p-dioxane, dimethoxyethane, n-methyl-pyrrolidone, n,n-dimethylacetamide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, benzyl benzoate, hexafluorobenzene, octafluorotoluene, pentafluorobenzonitrile, pentafluoropyridine, pyridine, dimethylformamide, hexamethylphosphoramide, nitromethane, and benzonitrile. These materials can be arranged in sheets, layers, or laminae, providing extremely high surface areas and oleophilicity. Advantageously, the combination of high surface area and oleophilicity enables these and other graphene-based materials to adsorb and/or absorb (collectively, “sorb”) relatively large quantities of certain fluid particles, particularly oil, hydrocarbons, and other organic fluids. In turn, this sorption of large quantities of particles facilitates the swelling or increase of volume of the article 10 when exposed to a fluid have a component, e.g., oil or hydrocarbons, that is sorbed by the compound 12.

[0010] By exfoliatable it is meant that the graphene-based material is able to undergo an exfoliation process. Exfoliation as used herein refers to the creation of individual sheets, planes, layers, laminae, etc. (generally, “layers”) of a graphene-based material; the delamination of the layers; or the enlargement of a planar gap between adjacent ones of the layers. In this way, the purpose of exfoliation is to increase the available surface area per unit volume or mass of the graphene-based material. This is particularly useful with respect to large fluid particles, e.g., as in heavy oil, which cannot fit between tightly packed layers. Examples of exfoliation include chemical, physical and/or mechanical processes such as heating of graphite intercalation compounds; sonication of graphite, graphite intercalation compounds and functionalized graphite in solvent systems; thermal annealing of graphite oxide; abrasion, shearing, stamping, or milling of graphite particles; removal of layers by adhesive tapes, etc., although those of ordinary skill in the art will appreciate that any other method now known or hereafter discovered can be used to exfoliate a graphene-based material.

[0011] In one embodiment, the compound 12 is formed by combining a graphene-based material 14 (i.e., as defined above) and an intercallant 16 according to a step 100. As shown in FIG. 2, the intercallant or intercalating agent 16 is a gaseous, liquid or solid material that is disposed between two layers 18 of the graphene-based material 14. In one embodiment, the intercallant 16 is formed by potassium and tetrahydrofuran, although other materials could be used. The layers 18 could be a single atom thick, or a plurality of atoms thick. The intercallant 16 results in a planar gap 20, initially designated with the numeral 20a, formed substantially perpendicularly between the layers 18. By heating the compound 12 according to a step 102, the intercallant 16 expands, thereby enlarging the gap 20 to a second size designated with the numeral 20b, during exfoliation of the compound 12. As will be described in more detail below, the step 102 is shown in its own FIG. 2 as the exfoliation of the graphene-based material could occur at various points during the process of FIG. 1. Further, those of ordinary skill in the art will readily appreciate that intercalation represents just one method of forming the exfoliatable compound 12 and that heating the intercallant 16 is just one example of exfoliating the compound 12 and that any other suitable exfoliatable compound and corresponding exfoliation method could be used.

[0012] Regardless of the method by which the compound 12 is formed, the compound 12 is combined with a matrix 22 in a step 104 in order to form a swellable material 24. In one embodiment, the compound 12 is milled (e.g., cryomilled) to form the compound 12 into a powder that is interspersed in the matrix 22. By swellable it is meant that the material 24 will swell, enlarge, or otherwise change in at least one direction when exposed to a suitable fluid. The matrix 22 could be a material that is also swellable, or a non-swellable material. In exemplary embodiments, the matrix material 22 is elastomeric, although other materials may be used depending on the ultimate purpose of the article 10. For example, in one embodiment, the matrix 22 is formed from acrylonitrile butadiene rubber, which provides good sealing characteristics and can be tailored to various degrees of swellability. In one embodiment, the matrix 22 and/or the swellable material 24 is prepared to include other additives or materials to tailor the properties of the resulting article 10, such as pressure rating, strength, swellability, pliability, durability, etc. In one embodiment, the matrix 22 and/or the material 24 includes carboxymethyl cellulose or some other water absorbent, water swelling, or hydrophilic additive in order to make the article 10 also swellable upon exposure to aqueous fluids. In this way, the article 10 can be made to be swellably responsive to oil, water, or dual-swellable combinations thereof.

[0013] The swellable material 24 is then formed in a step 106 into the article 10. The forming of the step 106 could including suitable molding, machining, shaping, or other process for giving a desired shape and dimensions to the article 10. In one embodiment, as noted previously herein, the swellable material 24 enables the article 10 to be swellably responsive to a fluid that is at least partially defined by oil or hydrocarbons, which are readily sorbed by the graphene-based material in the compound 12.

[0014] According to a step 108 of the illustrated embodiment, after forming the article 10 a system 26 is formed by disposing the article 10 with a tubular 28. In one embodiment, the material 24 is directly rolled onto the tubular to form the system 26 in a single step that combines the illustrated steps 106 and 108. In one embodiment, the tubular is part of a string, such as a production string, or some other component of a borehole completion. Of course, the article 10 could take any other shape for installation on or with non-tubular members, the article 10 could be radially inwardly installed as opposed to outwardly radially as shown, etc. Lastly, the article 10 is exposed to a suitable fluid in a step 110 in order to increase the volume of the article 10. In the illustrated embodiment, the swelling of the article 10 enables the article 10 to act to sealingly engage with a borehole 30 in order to isolate the borehole 30 on opposite sides of the article 10. Of course, the article 10 could be used in cased boreholes, or in any annulus formed between radially adjacent structures. Additionally, the swelling could be used for any combination of sealing, isolation, actuation, absorbing, etc., and one of ordinary skill in the art will recognize a myriad of isolation, packer, actuation, absorbing, and sealing devices that would benefit from the swellable materials and articles discussed herein.

[0015] As noted above, the step 102 could occur at various points in the general process of FIG. 1. For example, the graphene-based material could be exfoliated before, during, or after the steps 100, 104, 106, 108, or 110. It is noted that some of the benefits of exfoliating the graphene-based material could be negated during the forming in the step 106, particularly if the material 24 is compressed, e.g., in a mold, in order to form the article 10, as this may urge the graphene/graphite layers (e.g., the layers 18) closer together. In one embodiment utilizing the intercallant 16, the exfoliation illustrated in step 102 and FIG. 2 occurs after the article 10 is formed in the step 106 by heating the article 10. The heating could occur at surface, downhole, or any other desired location. In one embodiment, exposure to a downhole environment provides the heating necessary to exfoliate the graphene-based material by expanding the intercallant 16, while in other embodiments a heat source, such as a heated fluid, exothermic reaction, electrical current, etc. is provided. Advantageously, this enables the exfoliation to occur after all forming processes have occurred such that the graphite/graphene layers are not subjected to any processes that may urge them back together, thereby reducing the surface area that is accessible to particles (particularly relatively large particles) in the fluid to which the article 10 is responsive. In another embodiment, exfoliation of a graphite intercalation compound is achieved by passing an electric current through intercalated graphite or adjacent metallic components. In yet another embodiment, exfoliation of a graphite intercalation compound is achieved by inductive heating (e.g., producing eddy currents in the intercalated graphite/graphene particles). In yet another embodiment, exfoliation is achieved by applying ultrasonic frequencies to the graphene-based material. Without wishing to be bound by any particular theory, sonic frequencies may disrupt bonding between the adjacent atomic planes in graphene-based materials and/or induce chemical reactions of the intercalating agent within the galleries formed by graphene planes which result in the exfoliation of the graphene-based materials. Again without wishing to be bound by any particular theory, such effects may be induced by short-lived, localized disturbances (e.g., a hot spot) produced by the implosion of bubbles in the course of acoustic cavitation of the solvent. In yet another embodiment, exfoliation of graphite intercalation compounds is achieved by reacting the intercalating agent to increase the distance between the adjacent graphene planes in graphene-based materials. This can be achieved when the dimensions or occupied volumes of reaction products are larger than the dimensions or initial volumes of the intercalating agent, when a plurality of product molecules, atoms, or a combination thereof per molecule of the intercalating agent is produced, or when the formed reaction products have high kinetic energy (e.g., in order to heat the graphite intercalation compound and assist in exfoliation). For example, the intercalating agent could be hydrolyzed. In one embodiment, an antimony pentachloride intercalating agent is hydrolyzed upon contact with water molecules to produce Sb₂O₅ and hydrochloric acid. Any such product molecules or atoms can be further reacted to produce an even greater number of product molecules for assisting in the exfoliation process. Of course, any combination including any of the above could be utilized.

[0016] While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.