INFLATABLE METAL MATERIAL WITH SILICA

Abstract

INFLATABLE METALLIC MATERIAL WITH SILICA A production column may incorporate an inflatable metallic material to provide a bottom hole seal. The inflatable metallic material can react with a silica material and a water-based fluid to cause the inflatable metallic material to inflate and form a seal in a flow path partially defined by the production column.

Description

Title of the invention: Swellable metallic material with silica Technical field

[0001] The present disclosure relates generally to materials usable in a downhole environment to create a seal. More specifically, but without limitation, this disclosure relates to a swellable metallic material reacting with a silicate and a water-based fluid to form a metal hydrate for a downhole seal and / or anchor. Context

[0002] Various materials may be used to produce sealing elements in wellbore environments. The sealing elements may be used, for example, to form annular seals in a wellbore. The annular seals may isolate fluid or pressure within portions of a wellbore flow path from other portions of the flow path. Metallic materials may be used to form seals; however, some metallic materials may lack the integrity necessary to provide an effective seal. Brief description of the drawings

[0003] [Fig.l] is a diagram of a well system that includes a production string having a swellable metallic material positioned around the production string to form a seal, according to one aspect of the present disclosure.

[0004] [Fig.2A] is a cross-sectional view of a production string having a swellable metallic material to form a seal in an initial unexpanded state, according to one aspect of the present disclosure.

[0005] [Fig.2B] is a cross-sectional view of the production string having the swellable metallic material of [Fig.2A], in an expanded state forming a seal, according to one aspect of the present disclosure.

[0006] [Fig.3A] is a cross-sectional view of a production string having a swellable metallic material to form a seal in an initial unexpanded state, according to another aspect of the present disclosure.

[0007] [Fig. 3B] is a cross-sectional view of the production string having the swellable metallic material of [Fig. 3A], in an expanded state forming a seal, according to another aspect of the present disclosure.

[0008] [Fig.4A] is a cross-sectional view of a production string having a swellable metallic material to form a seal in an initial unexpanded state, according to another aspect of the present disclosure.

[0009] [Fig.4B] is a cross-sectional view of the production string having the swellable metallic material of [Fig.4A], in an expanded state forming a seal, according to another aspect of the present invention. Detailed description

[0010] Certain aspects and features relate to a downhole positionable assembly in a wellbore having an oilfield tubular member, e.g., a tubing string, coiled tubing, or similar tubular members, having a swellable metallic material positioned at least partially around the tubing string to form a seal in a downhole environment. The swellable metallic material may react with silica, e.g., but not limited to, amorphous silica, and a water-based fluid to cause the swellable metallic material to swell or expand to form a fluid-tight seal in a flow path within the wellbore, e.g., but not limited to, within an annulus of the wellbore.The term silica as used herein refers to any molecule that is a combination of silicon and oxygen, although other molecules may also be included. The silica may facilitate the chemical reaction of the swellable metal material with the water-based fluid to form a final product that is a "hydrated metal silicate." The metal of the hydrated metal silicate may be, for example, magnesium, aluminum, zinc, silicon, calcium, iron, nickel, or a combination of metals. The silica may be included within the swellable metal material, proximate the swellable metal material, within the water-based fluid, or any suitable combination thereof.The water-based fluid in contact with the swellable metallic material and silica may cause the swellable metallic material to swell and form the fluid-tight seal in a flow path, for example, but not limited to, an annulus of the wellbore. The fluid-tight seal may prevent fluid flow between two separate portions of the flow path, for example, but not limited to, a flow path along an inner diameter of the tubular or a flow path along an outer diameter of the tubular. The swellable metallic material may be positioned at various points along a tubular string to form multiple fluid seals at various locations around the tubular string as the swellable metallic materials react with silica and the water-based fluid.

[0011] Seals and / or anchors formed according to aspects of the present disclosure may improve seal strength, anchor strength, and / or seal setting behavior. In addition, the final hydrated metal silicate product may enable significant mechanical performance in wellbore applications. For example, a hydrated magnesium silicate (MSH) made from magnesium may be able to provide four to five times greater compressive strength than magnesium hydroxide. Silica may block cement pores within a wellbore, and thus, the permeability of the final product may be reduced.In addition, silica can increase the thixotropic behavior of a partially formed swellable metallic material, which can reduce the collapse behavior of the metallic material and increase the resistance of the metallic material to crossflow within the wellbore. The final product can also provide higher differential pressure capability and higher anchoring strength. In addition, the hydrated metal silicate final product can be more stable in a wellbore operation when exposed to other downhole chemicals. The improved properties provided by the hydrated metal silicate final product can enable improved applications of expanding metal technology and can also expand the scope of expanding metal technology.

[0012] The system having the swellable metallic material and the water-based fluid for inducing a chemical reaction may comprise silica according to several different embodiments. In some embodiments, the silica may be introduced into the system at the surface through the water-based fluid. In some embodiments, the silica may be introduced directly into the swellable metallic material. In some embodiments, the silica may be introduced into the system by being positioned proximate to the swellable metallic material. In any example, the silica may be positioned to contact the swellable metallic material and the water-based fluid to cause the chemical reaction.

[0013] These illustrative examples are intended to familiarize the reader with the general subject matter discussed herein and are not intended to limit the scope of the concepts disclosed. The following sections describe various additional features and examples with reference to the drawings, but, like the illustrative aspects, should not be used to limit the present disclosure.

[0014] [Fig.l] is a diagram of a well system 100 that includes an oilfield tubular member, for example, but not limited to, a production string 116 having an inflatable metallic material 114 positioned around the production string 116 to form a seal, according to an example of the present disclosure. The well system 100 may include a casing string 102 positioned in a wellbore 104 that has been formed in a surface 106 of the earth and through the subterranean formation 118. The well system 100 may have been constructed and completed in any suitable manner, for example, by using a drilling assembly having a drill bit to create the wellbore 104. The casing string 102 may include tubular casing sections connected by butt couplings. In some aspects, the casing string 102 may be made of a suitable material such as steel. Within the wellbore 104, cement 110 may be injected and allowed to set between an outer surface of the casing string 102 and an inner surface of the wellbore 104.In an inner surface of the casing string 102, there may be a production string (or work string) 116. The production string 116 may extend from the surface 106 into the wellbore 104. In some aspects, the production string 116 may comprise a series of articulated pipes, in some aspects, the production string 116 may be a coiled tube. An annular space 108 defining a flow path may be formed between an inner surface of the casing string 102 and an outer surface of the production string 116. In some aspects, the well system 100 may not include the casing string 102, instead the production string 116 may extend within the wellbore 104 defining a flow path within an annular space between the outer surface of the production string 116 and the wellbore 104.At the surface 106 of the wellbore 104, a shaft assembly 112 may be joined to the casing string 102. The shaft assembly 112 may include a set of valves, spools, fittings, etc. to direct and control the flow of fluid (e.g., oil, gas, water, etc.) into or out of the wellbore 104 within the casing string 102. For example, a pump 130 (e.g., well stimulation pumping equipment) may be coupled to the shaft assembly 112 to inject a wellbore fluid into the wellbore 104. In some aspects, the wellbore fluid (not shown in [Fig.l]) may be a water-based fluid (e.g., brine, wellbore cleaning fluid) injected downhole to react with the swellable metallic material 114 to form a seal.

[0015] In some embodiments, the swellable metallic material 114 may be wrapped at least partially around an outer surface of the production string 116 before the production string 116 is positioned downhole. In some aspects, the swellable metallic material 114 may be positioned at multiple intervals along the production string 116 such that the swellable metallic material 114 isolates sections of the production string 116. The Swellable metal material 114 may also be in a suitable position to be in contact with the wellbore fluid. Silica, including but not limited to SiO2, may be included with the swellable metal material 114, proximate the swellable metal material 114, or with the water-based fluid according to various embodiments described with respect to Figures 2A-4B. In some aspects, the pump 130 at the well system 100 may be used to inject the water-based fluid into the annulus 108 to bring the water-based fluid into contact with the swellable metal material 114 and the silica.

[0016] In some aspects, the silica may be an amorphous silica. The silica may be, for example, but not limited to, microsilica or silica fume powder. Additionally or alternatively, the silica may be derived from industrial waste such as rice husk ash, fly ash, or ground granulated blast furnace slag (GGBS). In addition, the silica may be derived from metakaolin, silicon dioxide, silica gel, colloidal silica, fumed silica, fused silica, a silicate (e.g., magnesium silicate, potassium silicate, sodium silicate, calcium silicate, ethyl silicate, zirconium silicate, asbestos, or talc), a silicic acid solution, or pozzolans (e.g., diatomaceous earth). In some aspects, the silica may be provided in solid or liquid form.In some aspects, the silica may be a spheroid with an approximate diameter of between about 1 nm and about 1 mm or any suitable diameter within this range, for example, between about 1 nm and 800 nm, between about 100 nm and about 600 nm, between about 200 nm and about 500 nm, or any other suitable diameter range. In some aspects, the amorphous silica may be cylindrical, flaked, or of any other shape.

[0017] [Fig. 2A] is a cross-sectional view of an oilfield tubular member, for example, but not limited to, a tubing string 202 positioned within a casing string 204. In some aspects, the tubing string 202 may be a coiled tube. The tubing string 202 may include a swellable metallic material 206 positioned around the tubing string 202. The swellable metallic material 206 may include silica 208 distributed within the swellable metallic material 206. In some aspects of the present disclosure, the silica fume powder may be pressed into pellets, which may then be incorporated into the swellable metallic material 206. Exemplary processes for incorporating the silica 208 into the swellable metallic material 206 include a forging process or a powder metallurgy process, although any suitable process may be used.In certain aspects of the present disclosure, silica 208 may be incorporated into . the swellable metal material 206 during a compression step after the swellable metal material 206 has been formed.

[0018] The swellable metal material 206 may be a solid metal alloy. In some aspects, the swellable metal material 206 may be made of a reactive metal such as magnesium, aluminum, zinc, iron, silicon, calcium, strontium, or another suitable metal, or any suitable combination thereof. In some aspects, a metal alloy may be used to modify a strength of the swellable metal material 206, modify a reaction rate of the swellable metal material, or any suitable combination thereof. In some aspects, copper, iron, or nickel may be added to the reactive metal to accelerate the reaction rate. The metal alloy may result in at least a portion of the swellable metal material 206 being a reactive metal. In some aspects, the swellable metal material 206 may be manufactured by extrusion, forging, or tubing.In some aspects, the reactive metal may be mixed into a polymer to create the swellable metal material 206.

[0019] Before a water-based fluid 210 is pumped into an annular space 205 between the production string 202 and the casing string 204, the swellable metallic material 206 may be in an initial unexpanded state. In its initial position before expansion, the swellable metallic material 206 may not contact an internal surface of the casing string 204. As illustrated in [Fig.2B], the water-based fluid 210 may be injected into the annulus 205 of the wellbore to contact the swellable metallic material 206. The water-based fluid 210 may contact the swellable metallic material 206 and initiate a chemical reaction between the swellable metallic material 206, including the silica 208. In some embodiments, the water-based fluid 210 may include additional silica to assist in the chemical reaction.The swellable metal material 206 may be electrically conductive and / or thermally conductive. In some aspects, the swellable metal material 206 may have a thickness of about 1 / 10 inch or more.

[0020] In response to the chemical reaction, the swellable metal material 206 may expand to form a reactive portion 212. During the chemical reaction, metal ions are formed and the dissolution of the silica 208 may form silicate ions almost simultaneously. In some aspects, the swellable metal material 206 may be converted to metal oxide (e.g., MgO), metal hydroxide (e.g., Mg(OH)2), and hydrated metal silicate (e.g., MSH, or (MgO)3(SiO2)2(H2O)2 + H2O) during the various stages of the reaction. In some aspects, the swellable metal material 206 may initially react with the water-based fluid 210 to form an intermediate stage product that is a metal oxide. In some aspects, the metal oxide may then react with water to form a final product that is a metal hydroxide. Where the swellable metal material 206 is located, the magnesium (Mg) may become magnesium oxide (MgO), and then the magnesium oxide may become magnesium hydroxide (Mg(OH)2), as demonstrated in Equations 1 and 2.

[0021] Mg + H2O —> MgO + H2 (1)

[0022] MgO + H2O Mg(OH)2 (2)

[0023] The reaction of the swellable metal material 206 may occur in a dissolution step and a precipitation step. In the case where Mg transforms into Mg(OH)2 , the reaction may be represented by the dissolution of MgO in equation 3 and the precipitation of Mg(OH)2 in equation 4.

[0024] MgO (s) + H2O Mg2+ (aq) + 2OH (aq) (3)

[0025] Mg2+ ( aq ) + 2OH ( aq Mg(OH)2(s) (4)

[0026] The dissolution of MgO (Equation 3) may result in the formation of free Mg+2 ions. Subsequently, the silica 208, represented in this non-limiting example as (SiO2>) present in the system comprising the swellable metallic material 206 may undergo a silica dissociation reaction, as in Equations 5 and 6, and produce additional free ions with which the free Mg+2 ions may chemically combine.

[0027] SiO2 + 2OH -> H2SiO42 (5)

[0028] SiO2 + OH + H2O -> H3SiO4 (6)

[0029] In some aspects, dissociation of silica 208 may occur under elevated pH conditions. The silica (SiO2) may dissociate into its silicate ions, and the Mg+2 ions may react with the additional free silicate ions to form a new product that is a hydrated metal silicate, particularly MSH, as in Equation 7.

[0030] 3Mg+2 + 6OH + 2SiO2 (MgO)3(SiO2)2(H2O)2 + H2O (7)

[0031] The reactive portion 212 corresponding to the swellable metallic material 206 in its expanded form, defining the seal, comprises the final product of the chemical reaction, a “hydrated metal silicate”. While the reactive portion 212 represents the entirety of the swellable metallic material 206 reacting with the silica 208 and the water-based fluid 210 to form a hydrated metal silicate, a portion of the swellable metallic material 206 may not undergo the chemical reaction and may retain its original metallic form. When the swellable metallic material 206 is magnesium, the final product forming the reactive portion 212 is hydrated magnesium silicate (MSH). Examples of potential forms of the MSH reaction product may include Mg3(Si2O5)(OH)4, Mg3(Si2O5)(OH)4, Mg3(Si2O5) (0H)4, Mg4(Si6O15)(OH)2-6H2O, Ca0.25(Mg,Fe)3((Si,Al)4O10)(OH)2-nH2O, and Mg3(Si4O io)(OH)2. MSH may be a derivative of magnesium hydroxide and result in an end product that is slightly different from magnesium hydroxide such that the MSH has different properties than magnesium hydroxide. In some aspects, the swellable metal material 206 may be formed from an alternative metal material as described in more detail below, resulting in the end product forming the reactive portion 212 comprising a “hydrated metal silicate” of the alternative metal material. For example, the resulting end product may be CSH or CASH, in addition to other potential “hydrated metal silicate” end products.

[0032] Although the above reaction is described with respect to the swellable metallic material 206 that undergoes the chemical reaction as magnesium, it should be understood that the reaction can occur similarly for any suitable alternative metallic material that can be used to produce the swellable metallic material 206. For example, any of magnesium, aluminum, zinc, iron, silicon, calcium, strontium, or any suitable combination thereof.

[0033] The reactive portion 212 corresponding to the swellable metallic material 206 in its expanded form extends between the outer surface of the production string 202 and the inner surface of the casing string 204 to form a fluid-tight seal in a flow path, as illustrated in Figures 2A-2B as the annular space 205 and may block fluid flow through the annular space 205. Although only a portion of the swellable metallic material 206 is shown in Figures 2A-4B, additional portions of swellable metallic material 206 may be positioned around the production string 202.

[0034] The swellable metal material 206 may be soluble as a result of reacting with the silica 208 and the water-based fluid 210 to form the reactive portion 212. For example, when the silica 208 reacts with the swellable metal material 206, there may be a corresponding expansion of the solid phase of the swellable metal material 206, causing the swellable metal material 206 to swell. In some embodiments, where the swellable metal material 206 is magnesium, there may be an admixture of sufficient silica 208 to have a complete reaction that renders the formation of MSH. In addition to MSH, the formation of Mg(OH)2 may still be observed as part of the final product, depending on the weight ratio of the initial materials Mg and SiO2.In some embodiments, the ratio of Mg:SiO2 materials may be 1:20, 1:3, 1:1, 10:1 or 100:1, or any other suitable ratio that may form some amount of metal hydroxide.

[0035] In some aspects, the dissolution of silica 208 or the amount of silica 208 may be enhanced by including silica-enhancing chemicals in the fluid (e.g., brine) that facilitate the chemical reaction. Silica-enhancing chemicals may be used in the fluid to regulate the pH of the fluid and thereby enhance the dissolution or amount of silica 208. In a preferred embodiment, sodium hexametaphosphate may be used. In various embodiments, other chemicals may be used to regulate the pH of the fluid. Examples of silica-enhancing chemicals may include sodium metasilicate, sodium hydroxide, and sodium orthophosphate. The silica-enhancing chemicals may be dissolved in the water-based fluid 210 prior to injecting the water-based fluid 210 to contact the swellable metal material 206.

[0036] [Fig. 3A] is a cross-sectional view of an oilfield tubular member, for example, but not limited to, a tubing string 302 positioned within a casing string 304. In some aspects, a tubing string 302 may be a coiled tube. The tubing string 302 may include a swellable metallic material 306 positioned around the tubing string 302. The swellable metallic material 306 may include silica 308 located separately from the swellable metallic material 306. In some aspects, for example as shown in [Fig. 3A], silica granules 308 may be embedded within an encapsulation (or coating) 309. The encapsulation 309 may be a material that is degradable in response to contact with water or in response to an application of a predetermined temperature.The encapsulation 309 may be, for example, but not limited to, an aliphatic polyester, a soluble metal alloy, or a water-soluble urethane. Other examples of the material of the encapsulation 309 may include a wax, a polymer, or a fusible alloy that melts at a predetermined temperature. The encapsulation 309 may include a single silica particle or it may include many particles. The silica 308 may be positioned adjacent to the swellable metal material 306, but may not be incorporated directly into the swellable metal material 306. A plurality of silica 308 in the encapsulation 309 may be used, depending on a selected weight ratio of the swellable metal material 306 to the silica 308. In some aspects, the silica 308 may be positioned adjacent to the swellable metal material 306 in a loose form.In one embodiment, the silica 308 is attached to the portion a of the production string with a material that is degradable in response to contact with water or in response to an application of a predetermined temperature. Degradation of the bond causes the silica 308 to be in proximity to the swellable metal material 306. In some embodiments, the silica 308 . may be placed radially adjacent to the swellable metallic material 306, axially adjacent to the swellable metallic material 306, or intercalated with the swellable metallic material 306. In some aspects, where the amorphous silica 308 is intercalated with the swellable metallic material 306, the silica 308 may be placed along the production string 302 between the multiple portions of the swellable metallic material 306 positioned along the production string 302. The encapsulation 309 may be pumped downward from the surface 106 of the wellbore 104 to be positioned adjacent to the swellable metallic material 306.

[0037] In some aspects, the silica 308 may be an amorphous silica. The silica may be, for example, but not limited to, microsilica or silica fume powder. Additionally or alternatively, the silica may be derived from industrial waste such as rice husk ash, fly ash, or ground granulated blast furnace slag (GGBS). In addition, the silica 308 may be derived from metakaolin, silicon dioxide, silica gel, colloidal silica, fumed silica, fused silica, a silicate (e.g., magnesium silicate, potassium silicate, sodium silicate, calcium silicate, ethyl silicate, zirconium silicate, asbestos, or talc), a silicic acid solution, or pozzolans (e.g., diatomaceous earth). In some aspects, the silica may be provided in solid or liquid form.In some aspects, the silica may be a spheroid with an approximate diameter of between about 1 nm and about 1 mm or any suitable diameter within this range, for example, between about 1 nm and 800 nm, between about 100 nm and about 600 nm, between about 200 nm and about 500 nm, or any other suitable diameter range. In some aspects, the silica 308 may be cylindrical, flake, or any other shape.

[0038] In some aspects, before a water-based fluid 310 is pumped into the annulus 305, the swellable metallic material 306 may not be in contact with the casing string 304. [Fig. 3B] shows a cross-sectional view of the tubing string of [Fig. 3A] having the swellable metallic material 306 in an expanded state forming a seal extending between the tubing string 302 and the casing string 304 as a result of a chemical reaction between the swellable metallic material 306, the silica 308, and a water-based fluid 310. As illustrated in [Fig. 3B], the water-based fluid 210 may be injected into the annulus 305 of the wellbore to contact the swellable metallic material 306 and the silica 308.The water-based fluid 310 in contact with the swellable metal material 306 and the silica 308 may initiate a chemical reaction between the swellable metal material 306, the silica 308, and the water-based fluid 310. The chemical reaction between the swellable metal material 306, the silica 308, and the water-based fluid 310 may result in the formation of a "hydrated metal silicate" as described above. For example, when the swellable metal material . 306 comprises magnesium, the end product of the chemical reaction may be a “hydrated magnesium silicate.” In some embodiments, the water-based fluid 310 may include additional silica 308 to assist in the chemical reaction. In some aspects, the encapsulation 309 of the silica 308 may dissolve in response to contact with the water-based fluid 310. In response to the chemical reaction, the swellable metal material 306 may form a reactive portion 312. The same chemical reaction described with respect to FIGS. 2A-2B may occur. The swellable metal material 306 may thus undergo the chemical reaction to form a “hydrated metal silicate” and, in doing so, may expand or swell to form a seal between the production string 302 and the casing string 304.In some aspects, the well system may not include the casing string 304 and the reactive portion 312 corresponding to the swellable metallic material 306 in its expanded form may extend between the production string 302 and the wellbore 104. The swellable metallic material 306 in its expanded form corresponding to the reactive portion 312 may form a seal within the annulus 305 of the wellbore 104 and may block fluid flow from the surface 106 of the wellbore 104. In some aspects, the swellable metallic material 306 may be positioned at various points along the production string 302 to form multiple seals at various locations around the production string 302 as the swellable metallic materials 306 react with the silica 308 and the water-based fluid 310.

[0039] [Fig.4A] is a cross-sectional view of an oilfield tubular member, for example, but not limited to, a production string 402 positioned within a casing string 404. In some aspects, the production string 402 may be a coiled tubing. The production string 402 may include a swellable metallic material 406 positioned around the production string 402. The swellable metallic material 406 may include silica 408 dissolved within a water-based fluid 410. [Fig. 4B] shows a cross-sectional view of the production string of [Fig. 4A] including the swellable metallic material 406 in an expanded state forming a seal extending between the production string 402 and the casing string 404 as a result of a chemical reaction between the swellable metallic material 406, the silica 408, and a water-based fluid 410.In some aspects, the water-based fluid 410 may be a wellbore cleaning fluid, brine, or any other suitable water-based fluid 410 usable for a wellbore operation. In some aspects, the silica 408 may be introduced as granules or powder flakes that are mixed into the water-based fluid 410. In some aspects, the silica 408 may be introduced into the water-based fluid 410 as part of a filter cake that has . was previously applied to the wellbore 104. In some aspects, the silica 408 may be dissolved in the water-based fluid 410 before the water-based fluid 410 is circulated downhole.

[0040] In some aspects, the silica 408 may be an amorphous silica. The silica may be, for example, but not limited to, microsilica or silica fume powder. Additionally or alternatively, the silica 408 may be derived from industrial waste such as rice husk ash, fly ash, or ground granulated blast furnace slag (GGBS). In addition, the silica may be derived from metakaolin, silicon dioxide, silica gel, colloidal silica, fumed silica, fused silica, a silicate (e.g., magnesium silicate, potassium silicate, sodium silicate, calcium silicate, ethyl silicate, zirconium silicate, asbestos, or talc), a silicic acid solution, or pozzolans (e.g., diatomaceous earth). In some aspects, silica 408 may be provided in solid or liquid form.In some aspects, silica 408 may be a spheroid with an approximate diameter of between about 1 nm and about 1 mm or any suitable diameter within this range, for example, between about 1 nm and 800 nm, between about 100 nm and about 600 nm, between about 200 nm and about 500 nm, or any other suitable diameter range. In some aspects, silica 408 may be cylindrical, flake, or any other shape.

[0041] As illustrated in [Fig. 4B], the water-based wellbore fluid 410 may be injected into a flow path, e.g., an annulus 405, of the wellbore 104 containing the swellable metal material 406. As described with respect to Figures 2A-3B above, a chemical reaction may occur between the swellable metal material 406, the silica 408, and the water-based fluid 410 to form a “hydrated metal silicate.” The chemical reaction between the swellable metal material 406, the silica 408, and the water-based fluid 410 may result in the formation of a “hydrated metal silicate” as described above. For example, when the swellable metal material 406 comprises magnesium, the end product of the chemical reaction may be a “hydrated magnesium silicate.” In response to the chemical reaction, the swellable metal material 406 may form a reactive portion 412.The same steps of the chemical reaction described with respect to Figures 2A-2B may occur. The swellable metallic material 406 upon formation of the "hydrated metal silicate" may swell or expand to form a seal between the outer surface of the production string 402 and the inner surface of the casing string 404. In some aspects, the well system may not include the casing string 404 and the reactive portion 412 corresponding to the swellable metallic material 406 in its expanded form may extend between the production string 402 and the wellbore 104. The reactive portion 412 corresponding to the . Swellable metallic material 406 in its expanded position can thus result in a fluid-tight seal within the annular space 405 and can block any fluid flow. The swellable metallic material 406 can be positioned at various points along the production string 402 to form multiple seals at various locations around the production string 402 as the swellable metallic materials 406 react with the silica 408 and the water-based fluid 410.

[0042] In some aspects, a production string, including a coiled production string, may comprise a swellable metallic material that can react with silica and a water-based fluid to form a "hydrated metal silicate" which, upon so reacting, causes the swellable metallic material to swell or expand and form a seal within a wellbore, is provided according to one or more of the following examples:

[0043] Example 1 is an apparatus that may include an oilfield tubular positionable downhole. The apparatus may include a swellable metallic material positioned proximate a surface of the oilfield tubular to swell and drive a fluid-tight seal in a flow path defined in part by the oilfield tubular in response to contact of the swellable metallic material with a water-based fluid. The swellable metallic material may include silica.

[0044] Example 2 is the apparatus according to Example 1, the apparatus may further comprise silica which is an amorphous silica.

[0045] Example 3 is the apparatus according to any one of Examples 1 to 2, the apparatus may have the water-based fluid comprising a silica-enhancing chemical used to enhance dissolution of silica within the swellable metal material.

[0046] Example 4 is the apparatus according to any one of Examples 1 to 3, the water-based fluid may further comprise additional silica.

[0047] Example 5 is the apparatus according to any one of Examples 1 to 4, the swellable metal material may be configurable to react with the silica and the water-based fluid to yield a final product that is a hydrated metal silicate.

[0048] Example 6 is the apparatus according to any one of Examples 1 to 5, the silica may be microsilica or silica fume powder.

[0049] Example 7 is the apparatus according to any one of Examples 1 to 6, the swellable metallic material may comprise at least one of magnesium, aluminum, zinc, iron, calcium or strontium.

[0050] Example 8 is an apparatus that may include a downhole positionable oilfield tubular with an inflatable metallic material capable of at least partially surrounding a surface of the tubular member, and a silica material positioned proximate the swellable metallic material to react with the swellable metallic material and the water-based fluid to yield a final product that is a hydrated metal silicate.

[0051] Example 9 is the apparatus according to Example 8, further the silica material may be at least partially encapsulated within a degradable coating.

[0052] Example 10 is the apparatus according to Examples 9, further the degradable coating of the silica material may be soluble in response to contact with the water-based fluid.

[0053] Example 11 is the apparatus according to any one of Examples 9 to 10, further the degradable coating of silica material may be soluble in response to exposure to a predetermined temperature.

[0054] Example 12 is the apparatus according to Examples 9 to 11, furthermore the degradable coating of the silica material may be an aliphatic polyester or a water-soluble urethane.

[0055] Example 13 is the apparatus according to Examples 8 to 12, furthermore the silica material may be an amorphous silica.

[0056] Example 14 is the apparatus according to Examples 8 to 13, furthermore the swellable metallic material may comprise at least one of magnesium, aluminum, zinc, iron, calcium or strontium.

[0057] Example 15 is a method of forming a seal in a wellbore that may include the steps of providing a swellable sealing element that is at least partially composed of a swellable metallic material, providing a silica material, and exposing the swellable sealing element to a water-based fluid, wherein the swellable metallic material swells in response to a chemical reaction with the water-based fluid and the silica material to form a hydrated metal silicate.

[0058] Example 16 is the process according to Example 15, furthermore the silica may be an amorphous silica.

[0059] Example 17 is the method according to Examples 15 to 16, furthermore the silica material may be provided in the water-based fluid.

[0060] Example 18 is the method according to Examples 15 to 17, furthermore the silica may be included inside the swellable metallic material.

[0061] Example 19 is the process according to Examples 15 to 18, furthermore the silica may be a microsilica or a silica fume.

[0062] Example 20 is the method according to Examples 15 to 19, in addition the swellable metallic material may comprise at least one of magnesium, aluminum, zinc, iron, calcium or strontium.

Claims

Claims

1. An apparatus for forming a seal in a wellbore comprising: an oilfield tubular member positionable downhole; a swellable metallic material (206, 306, 406) at least partially surrounding a surface of the tubular member; and a silica material (208, 308, 408), wherein the silica material is an amorphous silica, positioned proximate the swellable metallic material (206, 306, 406) to react with the swellable metallic material (206, 306, 406) and the water-based fluid (210, 310, 410) to yield a final product that is a hydrated metal silicate.

2. Apparatus for forming a watertight seal in a wellbore according to claim 1, wherein the silica material (208, 308, 408) is at least partially encapsulated within a degradable coating.

3. The apparatus of claim 2, wherein the degradable coating of silica material (208, 308, 408) is soluble in response to contact with the water-based fluid (210, 310, 410).

4. Apparatus for forming a watertight seal in a wellbore according to any one of claims 2 to 3, wherein the degradable coating of silica material (208, 308, 408) is soluble in response to exposure to a predetermined temperature.

5. Apparatus for forming a watertight seal in a wellbore according to any one of claims 2 to 4, wherein the degradable coating of silica material (208, 308, 408) is an aliphatic polyester or a water-soluble urethane.

6. An apparatus for forming a watertight seal in a wellbore according to claim 1, wherein the silica material (208, 308, 408) is included within the swellable metallic material.

7. An apparatus for forming a watertight seal in a wellbore according to any one of claims 1 to 6, wherein the swellable metallic material (206, 306, 406) comprises at least one of magnesium, aluminum, zinc, iron, calcium or strontium.

8. Apparatus for forming a fluid-tight seal in a wellbore according to any one of claims 1 to 7, wherein the swellable metallic material (206, 306, 406) swells and creates a fluid-tight seal in a flow path defined in part by the oilfield tubular in response to contact of the swellable metallic material (206, 306, 406) with the water-based fluid (210, 310, 410) and the silica material (208, 308, 408).

9. Apparatus for forming a watertight seal in a wellbore according to any one of claims 1 to 8, wherein the water-based fluid (210, 310, 410) further comprises an additional silica material (208, 308, 408).

10. An apparatus for forming a watertight seal in a wellbore according to any one of claims 1 to 9, wherein the water-based fluid (210, 310, 410) comprises a silica-enhancing chemical used to enhance dissolution of the silica material (208, 308, 408).

11. A method of forming a seal in a wellbore comprising: providing a swellable sealing element that is at least partially composed of a swellable metallic material (206, 306, 406); providing a silica material (208, 308, 408), wherein the silica material (208, 308, 408) is an amorphous silica; exposing the swellable sealing element to a water-based fluid, (210, 310, 410) wherein the swellable metallic material (206, 306, 406) swells in response to a chemical reaction with the water-based fluid (210, 310, 410) and the silica material to form a hydrated metal silicate.

12. 12. The method of claim 11, wherein the silica material (208, 308, 408) is provided in at least one of the water-based fluid (210, 310, 410) or the swellable metallic material (206, 306, 406).

13. 13. The method of any one of claims 11 to 12, wherein the silica material (208, 308, 408) is microsilica or silica fume.

14. 14. The method of claim 11, wherein the inflatable metallic material (206, 306, 406) comprises at least one among magnesium, aluminum, zinc, iron, calcium or strontium.

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