DEGRADABLE DEFORMABLE DIVERTERS AND SEALS

Abstract

A variable stiffness engineered degradable ball or seal having a degradable phase and a stiffener material. The variable stiffness engineered degradable ball or seal can optionally be in the form of a degradable diverter ball or sealing element which can be made neutrally buoyant.

Claims

1-29. (canceled)

30. A variable stiffness or deformable degradable component formed of a) degradable metal and 10-80 vol. % of a stiffness component, orb) degradable elastomer or polymer and 10-80 vol. % of a stiffness component.

31. The variable stiffness or deformable degradable component as defined in claim 30, wherein said variable stiffness or deformable degradable component is formed of said degradable elastomer or polymer and said stiffness component, said degradable elastomer or polymer forming a continuous phase in said first degradable component, said degradable elastomer or polymer having a 50-100 shore A hardness, and a strain to failure in tension or compression of at least 20%; said stiffness component forming a discontinuous second phase in said first degradable component, said stiffness component i) has a stiffness or hardness at of least five times a stiffness or hardness of said degradable elastomer or polymer, and/or ii) allows for deformation of said first degradable component when said first degradable component is exposed to a force that is 10-75% of a strength of said first degradable component prior to be deformed; said first degradable component has a stiffness or yield strength that changes when said first degradable component deforms, and wherein a maximum stiffness and/or yield strength of said first degradable component after deformation of said first degradable component is at least 1.3 times a stiffness of said first degradable component prior to deformation of said first degradable component.

32. The variable stiffness or deformable degradable component as defined in claim 30, wherein said stiffness component includes one or more of a flake, fiber, foil, microballoon, ribbon, sphere, and/or particle shape.

33. The variable stiffness or deformable degradable component as defined claim 30, wherein said stiffness component is uniformly dispersed in said first degradable component.

34. The variable stiffness or deformable degradable component as defined in claim 30, wherein 80-100% of said stiffness component is located inwardly from an outer surface of said first degradable component.

35. The variable stiffness or deformable degradable component as defined in claim 30, wherein said stiffness component includes one or more fillers selected from the group consisting of calcium carbonate, titanium dioxide, silica, talc, mica, sand, gravel, crushed rock, bauxite, granite, limestone, sandstone, glass beads, aerogels, xerogels, clay, alumina, kaolin, microspheres, hollow glass spheres, porous ceramic spheres, gypsum dihydrate, insoluble salts, magnesium carbonate, calcium hydroxide, calcium aluminate, and/or magnesium carbonate.

36. The variable stiffness or deformable degradable component as defined in claim 30, wherein said degradable elastomer or polymer includes an elastomeric material which includes at least two phases, a first phase includes one or more of natural rubber, vulcanized rubber, silicone, polyurethane, synthetic rubber, polybutadiene, nitrile rubber (NBR), polyisobutylene, acrylater-butadiene rubber and/or styrene butadiene rubber, and a second phase includes one or more of polyvinyl alcohol (PVA), poly vinyl chloride (PVC), polyethylene glycol, polylactic acid (PLA), polyvinylpyrrolidone or polymer derivatives of acrylic and/or methacrylic acid.

37. The variable stiffness or deformable degradable component as defined in claim 30, wherein said degradable metal is a degradable magnesium alloy.

38. The variable stiffness or deformable degradable component as defined in claim 30, wherein said first degradable components has a density that is a) ±20% a density of said fluid, or b) ±20% a density of sand, frac balls and/or proppant in said fluid.

39. The variable stiffness or deformable degradable component as defined in claim 30, wherein a density of said degradable elastomer or polymer is 0.01-1.2 g/cc.

40. The variable stiffness or deformable degradable component as defined in claim 30, wherein a density of said first degradable component is 0.95-1.3 g/cc.

41. The variable stiffness or deformable degradable component as defined in claim 30, wherein said first degradable component includes a swellable component that increases in volume upon exposure to said fluid.

42. A variable stiffness or deformable degradable component formed of: a) degradable metal and 10-80 vol. % of a stiffness component; said degradable metal include magnesium; said stiffness component forming a discontinuous second phase in said first degradable component; said stiffness component allows for deformation of said first degradable component when said first degradable component is exposed to a force that is 10-75% of a strength of said first degradable component prior to be deformed; said first degradable component has a stiffness or yield strength that changes when said first degradable component deforms, and wherein a maximum stiffness and/or yield strength of said first degradable component after deformation of said first degradable component is at least 1.3 times a stiffness of said first degradable component prior to deformation of said first degradable component; said stiffness component includes one or more of a flake, fiber, foil, microballoon, ribbon, sphere, and/or particle shape; said stiffness component is uniformly dispersed in said first degradable component; or b) degradable elastomer or polymer and 10-80 vol. % of a stiffness component; said degradable elastomer or polymer forming a continuous phase in said first degradable component; said degradable elastomer or polymer having a 50-100 shore A hardness, and a strain to failure in tension or compression of at least 20%; said stiffness component forming a discontinuous second phase in said first degradable component; said stiffness component i) has a stiffness or hardness at of least five times a stiffness or hardness of said degradable elastomer or polymer, and/or ii) allows for deformation of said first degradable component when said first degradable component is exposed to a force that is 10-75% of a strength of said first degradable component prior to be deformed; said first degradable component has a stiffness or yield strength that changes when said first degradable component deforms, and wherein a maximum stiffness and/or yield strength of said first degradable component after deformation of said first degradable component is at least 1.3 times a stiffness of said first degradable component prior to deformation of said first degradable component; said stiffness component includes one or more of a flake, fiber, foil, microballoon, ribbon, sphere, and/or particle shape; said stiffness component is uniformly dispersed in said first degradable component.

43. The variable stiffness or deformable degradable component as defined in claim 42, wherein said stiffness component includes one or more fillers selected from the group consisting of calcium carbonate, titanium dioxide, silica, talc, mica, sand, gravel, crushed rock, bauxite, granite, limestone, sandstone, glass beads, aerogels, xerogels, clay, alumina, kaolin, microspheres, hollow glass spheres, porous ceramic spheres, gypsum dihydrate, insoluble salts, magnesium carbonate, calcium hydroxide, calcium aluminate, and/or magnesium carbonate.

44. The variable stiffness or deformable degradable component as defined in claim 43, wherein said first degradable components has a density that is a) ±20% a density of said fluid, or b) ±20% a density of sand, frac balls and/or proppant in said fluid.

45. The variable stiffness or deformable degradable component as defined in claim 44, wherein said first degradable component includes a swellable component that increases in volume upon exposure to said fluid.

46. The variable stiffness or deformable degradable component as defined in claim 44, wherein said first degradable component is in the form of a diverter ball, diverter shape, or diverter plug.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0131] Reference may now be made to the drawings, which illustrate various embodiments that the disclosure may take in physical form and in certain parts and arrangements of parts wherein:

[0132] FIG. 1 illustrates the stress versus displacement for three different variable stiffness elastomer composites.

[0133] FIG. 2 illustrates a variable stiffness elastomeric composite consisting of hard spheres added at 30-70 vol. % to a dissolvable elastomer matrix.

[0134] FIG. 3 illustrates a textured, directionally-compliant variable stiffness engineered degradable thermoplastic elastomer material that can be used to form a ball or seal.

[0135] FIG. 4 illustrates a method of using flake or fiber that accomplishes a similar result as the approach illustrated in FIG. 3 in a pultruded or more easily moldable structure.

[0136] FIG. 5 illustrates a variable stiffness sealing ball or element encountering an opening in a well formation and deforming to form a seal in the opening.

[0137] FIG. 6 illustrates the orientation and the type of rigid (hard) filler in used in the elastomer structured seal/packer to control deformation and to inhibit or prevent extrusion and creep.

[0138] FIG. 7 illustrates the compressive strength as a function of strain for syntactic aluminum alloys that can be dissolved using an acid or gelbreaker or, alternatively, a hot caustic solution.

[0139] FIG. 8 is a graph illustrating the pressure ratings of various elastomeric composite balls over time.

[0140] FIG. 9 illustrates a partially degraded elastomeric composite ball.

DETAILED DESCRIPTION OF NON-LIMITING EMBODIMENTS

[0141] A more complete understanding of the articles/devices, processes and components disclosed herein can be obtained by reference to the accompanying drawings. These figures are merely schematic representations based on convenience and the ease of demonstrating the present disclosure, and are, therefore, not intended to indicate relative size and dimensions of the devices or components thereof and/or to define or limit the scope of the exemplary embodiments.

[0142] Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.

[0143] The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0144] As used in the specification and in the claims, the term “comprising” may include the embodiments “consisting of” and “consisting essentially of.” The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that require the presence of the named ingredients/steps and permit the presence of other ingredients/steps. However, such description should be construed as also describing compositions or processes as “consisting of” and “consisting essentially of” the enumerated ingredients/steps, which allows the presence of only the named ingredients/steps, along with any unavoidable impurities that might result therefrom, and excludes other ingredients/steps.

[0145] Numerical values in the specification and claims of this application should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement technique of the type described in the present application to determine the value.

[0146] All ranges disclosed herein are inclusive of the recited endpoint and independently combinable (for example, the range of “from 2 grams to 10 grams” is inclusive of the endpoints, 2 grams and 10 grams, all the intermediate values and all intermediate ranges).

[0147] The terms “about” and “approximately” can be used to include any numerical value that can vary without changing the basic function of that value. When used with a range, “about” and “approximately” also disclose the range defined by the absolute values of the two endpoints, e.g. “about 2 to about 4” also discloses the range “from 2 to 4.” Generally, the terms “about” and “approximately” may refer to plus or minus 10% of the indicated number.

[0148] Percentages of elements should be assumed to be percent by weight of the stated element, unless expressly stated otherwise.

[0149] The disclosure is directed to sealing arrangement that uses an engineered degradable thermoplastic elastomer or degradable metallic device (e.g., degradable metallic ball, etc.) to form seals in various openings in a well formation, The sealing of the engineered degradable thermoplastic elastomer or degradable metallic device is achieved by causing the engineered degradable thermoplastic elastomer or degradable metallic device to deform at the opening in the well formation. The deformation of the engineered degradable thermoplastic elastomer or degradable metallic device results in the stiffness and/or strength of the engineered degradable thermoplastic elastomer or degradable metallic device to increase. The density of the engineered degradable thermoplastic elastomer or degradable metallic device can be controlled (e.g., neutrally buoyant) to facilitate placement of the engineered degradable thermoplastic elastomer or degradable metallic device at or partially in the opening in the well formation. The engineered degradable thermoplastic elastomer or degradable metallic device is formulated to dissolve/degrade (e.g., dissolve/degrade in a completion fluid, including brine, guar gel, freshwater, produced water, etc., as a function of temperature or time, or accelerated or initiated under the action of a gelbreaker or other activator or controlled fluid) so that the deformed engineered degradable thermoplastic elastomer or degradable metallic device can be removed from the opening in the well formation, thereby resulting in the unsealing of the opening in the well formation. The engineered degradable thermoplastic elastomer or degradable metallic device is formulated to dissolve/degrade so that it can be safety removed from the opening without damaging the well formation.

[0150] Referring now to FIG. 1, there is illustrated the stress versus displacement for three different variable stiffness engineered degradable thermoplastic elastomers. As illustrated in FIG. 1, as load is applied to the variable stiffness engineered degradable thermoplastic elastomer ball or seal, significant deformation of the soft phase occurs in the variable stiffness engineered degradable thermoplastic elastomer ball or seal. After a certain point, the load in the variable stiffness engineered degradable thermoplastic elastomer ball or seal is transferred to the hard phase of the variable stiffness engineered degradable thermoplastic elastomer ball or seal, and the load increases at 5-100× the slope of the soft phase. Deformations of the variable stiffness engineered degradable thermoplastic elastomer ball or seal of about 5-50% are common before shifting from the low to high stiffness (slope). The increase in stiffness and hardness of the variable stiffness engineered degradable thermoplastic elastomer results in less deformation of the variable stiffness engineered degradable thermoplastic elastomer. As such, after the variable stiffness engineered degradable thermoplastic elastomer has undergone some deformation to partially or fully conform to the shape about an opening in a well formation so as to form a seal in/about the opening, further deformation of the variable stiffness engineered degradable thermoplastic elastomer is reduced or terminated so that the deformed variable stiffness engineered degradable thermoplastic elastomer is retained in its sealing position at/about the opening. As can be appreciated, if the stiffness of the variable stiffness engineered degradable thermoplastic elastomer does not increase, the variable stiffness engineered degradable thermoplastic elastomer would continue to deform and thereby be formed through the opening in the well formation and compromise the seal in the opening. The unique feature of the variable stiffness engineered degradable thermoplastic elastomer is its ability to deform so as to partially or fully conform to a shape of an opening in the well formation, thereby creating a seal in/about the opening, and thereafter resisting further deformation so as to maintain the deformed shape, thereby maintaining the seal in/about the opening. Generally, the variable stiffness engineered degradable thermoplastic elastomer is designed to deform about 10-75% (and all values and ranges therebetween). For example, a 3 in. diameter diverter ball formed of the variable stiffness engineered degradable thermoplastic elastomer could be caused to deform such that, if the diverter ball was flattened by a fluid pressure, the diameter of the diverter ball would decrease to about 2.7 in. (10% deformation) to 0.75 in. (75% deformation). As will be discussed in more detail with respect to FIG. 5, deformation of the variable stiffness engineered degradable thermoplastic elastomer does not need to be uniform throughout the variable stiffness engineered degradable thermoplastic elastomer when partially or fully sealing an opening. As illustrated in FIG. 5, only a portion of the spherical diverter ball has deformed, and wherein such deformation is at the location of the opening in the well formation. In the deformed region of the spherical diverter ball, the stiffening components have moved in close proximity to one another and/or are contacting one another, thereby resulting in increased stiffness and/or hardness in such deformed region, thus resisting further deformation in such region.

[0151] FIG. 2 illustrates a variable stiffness elastomeric composite consisting of hard spheres added at 30-70 vol. % to a dissolvable elastomer matrix. The hard spheres (e.g., microballoons, solid spheres, etc.) are illustrated as being generally uniformly dispersed in the dissolvable elastomer matrix prior to deformation of the variable stiffness elastomeric composite (State 1). In State 1, the variable stiffness elastomeric composite has a lower stiffness than in State 2. As a strain or load (indicated by the arrows) is applied to one or more regions of the variable stiffness elastomeric composite, the variable stiffness elastomeric composite is caused to be deformed when a sufficient strain or load is applied (State 2). The dissolvable elastomer matrix controls the stiffness of the variable stiffness elastomeric composite until the spheres begin to contact each other (e.g., dissolvable elastomer matrix is extruded from between the microballoons, bringing them into close or direct contact), at which point the stiffness of the variable stiffness elastomeric composite dramatically increases. In State 2, the hardness and stiffness of the variable stiffness elastomeric composite is greater than the hardness and stiffness of the variable stiffness elastomeric composite in State 1.

[0152] FIG. 3 illustrates a textured, directionally-compliant variable stiffness elastomeric composite that can be used to form a ball or seal. The crimped stiffness component (e.g., metal component, graphite component, plastic component, etc.) deforms with the dissolvable elastomer matrix until the stiffness component is straightened out or flattened, at which point the stiffness component becomes non-compliant (e.g., no long can be compressed) and the hardness and stiffness of the variable stiffness elastomeric composite dramatically increases. As illustrated in FIG. 3, the configuration of the stiffness component has a shape (e.g., repeating V-shape, sinusoidal shape, other non-straight shape, etc.) is such that when a load or strain is applied to a top of the variable stiffness elastomeric composite, the stiffness component can no longer be compressed in the Y direction and can no long increase in length in the X direction, thus becomes rigid or stiff in the X direction, thereby inhibiting or preventing deformation of the variable stiffness elastomeric composite in the X direction. As can be appreciated, some further deformation of the variable stiffness elastomeric composite in the Y direction may occur due to the spacing of the stiffness components from one another in the Y direction. As such, in State 1 prior to deformation, the variable stiffness elastomeric composite can be deformed in the X and Y direction. After deformation in State 2, the variable stiffness elastomeric composite is stiff for further deformation in the X direction but is still above to further deform in the Y direction. As can be appreciated, the orientation of the stiffness component in the variable stiffness elastomeric composite can be selected such that stiffness occurs in direction other than or in addition to the X direction when a load is applied to the variable stiffness elastomeric composite on the top and/or other outer surfaces of the variable stiffness elastomeric composite.

[0153] As can be appreciated, by combining using the stiffness components illustrated in FIGS. 2 and 3 in the variable stiffness elastomeric composite, control over stiffness/compliance in both X and Y directions can be obtained. By controlling the straightness of the stiffness components, which can be continuous or discontinuous, the amount of strain in the X direction before the variable stiffness elastomeric composite becomes rigid can be controlled with a high degree of precision. Such variable stiffness elastomeric composites can be highly useful in seals and can be fabricated by laminating, compounding, or rolling (e.g., foil or ribbon winding) processes.

[0154] FIG. 4 illustrates a variable stiffness elastomeric composite that includes a plurality of flakes or fibers for the stiffness component that accomplishes a similar result described above with regard to the variable stiffness elastomeric composite illustrated in FIG. 3. The variable stiffness elastomeric composite illustrated in FIG. 4 is generally a more easily moldable structure than the variable stiffness elastomeric composite illustrated in FIG. 3 due to the configuration of the stiffness components. As illustrated in FIG. 4, as the flakes and/or fibers align in the variable stiffness elastomeric composite during deformation of the variable stiffness elastomeric composite in the X and/or Y direction, the flakes and/or fibers inhibit or prevent further deformation in a direction to the applied force on the variable stiffness elastomeric composite. As can be appreciated, the stiffness components illustrated in FIGS. 2 and/or 3 can be combined with the stiffness components illustrated in FIG. 4.

[0155] The techniques for creating increased stiffness and/or hardness of the variable stiffness elastomeric composite when the variable stiffness elastomeric composite is deformed are particularly effective in controlling extrusion or creep of a seal formed of the variable stiffness elastomeric composite under load.

[0156] A non-limiting application for use of the variable stiffness elastomeric composite to sealing an opening in a well formation is illustrated in FIG. 5. Generally, the shape of the opening in a well formation is not uniformly circular. In fact, the openings in a well formation are typically non-uniform in shape, thereby making it difficult to seal the non-uniform opening using traditionally shaped spherical diverter balls. As illustrated in FIG. 5, the spherically shaped variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material is caused to deform and readily conform to the irregular surface and/or shape of the opening to create a seal at/in the opening. As illustrated in FIG. 5, the portion of the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material that is deformed increases in stiffness and/or hardness and thereby resists further deformation once a portion of the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material deforms at/in the opening and forms a seal at/in the opening. As illustrated in FIG. 5, only the region of the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material that is located about the opening is illustrated as being deformed; however, it can be appreciated that other regions of the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material can be deformed. Due to the increased harness and/or stiffness of the deformed variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material, the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material resists being pushed through the opening as illustrated in FIG. 5.

[0157] As partially illustrated in FIG. 5, as the diverter ball or seal that is at least partially formed of a variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material encounters the opening in the well formation (which can be non-circular or ragged), the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material deforms until a seal is made about/in the opening. Under continued applied pressure, the rigid or hard phase formed by the stiffening component begins to dominate in the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material after a controlled or certain amount of deformation of the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material. The deformed variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material densifies, thereby becoming stiffer and/or stronger, and thus forms a high strength, rigid plug that seals the opening in the well formation, but which deformed variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material resists further deformation to inhibit or prevent the deformed variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material from being extruded or pushed through the hole in the well formation.

[0158] The deformable variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material can also be fabricated in situ in the well formation. This can be accomplished by combining in the well formation the deformable and more stiffness components that are used to form the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material. The deformable and more stiffness components can be separately flowed into the well formation; however, this is not required. For example, a deformable variable stiffness elastomeric composite can be formed in situ in the well formation by flowing into the well formation a pill that is combination of metallic flakes or foil elastomeric material (e.g., powdered coating, etc.), whereby the pills are pressed together at or near an opening in the well formation to form a network of connected pills, thereby forming a deformable variable stiffness elastomeric composite that can be built up to form a seal in an opening in the well formation. The use of different cross-section stiffener components (e.g., X-shaped, hollow rods, syntactic metallic rods, etc.) combined with PVA or other plastic or elastic dissolvable material can be used to form a deformable variable stiffness elastomeric composite from this function in situ in the well formation for sealing an opening in the well formation.

[0159] The variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material can be used as a sealing element, O-ring, ring seal, packing element, or other type seal. FIG. 6 illustrates four (4) non-limiting useful variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material in a symmetric (only one-half shown) cross-section, and illustrate the stiffening component (e.g., rigid spheres, aligned flakes, fibers, or ribbons [oriented parallel to the compression orientation], random flakes or fibers, and/or chevron or structured stiff phase designs) in various configurations. These four non-limiting designs are particularly effective at preventing compression set, extrusion, and creep, particularly at elevated temperatures and pressures.

[0160] Another non-limiting design includes the use of metal encapsulation of all or part of the degradable elastomer (e.g., elastomer filled degradable metal tube or shape/extrusion), wound or laminated structure, or stacked ring or cone structure to prevent extrusion and enable higher pressure ratings to be met.

[0161] FIG. 7 illustrates the compressive strength as a function of strain for syntactic aluminum alloys that can be dissolved using an acid or a gelbreaker, or alternatively, a hot caustic solution. Initial crush strengths of 5,000-10,000 psi (and all values and ranges therebetween) are typical for 40 vol. % microballoon-reinforced alloys. Initial crush strength can be controlled by alloy and heat treatment selection, as well as microballoon size, strength (e.g., wall thickness), and content. Generally, microballoon content of the variable stiffness degradable deformable metallic material is 10-60 vol. % (and all values and ranges therebetween), and typically 30-50 vol. %. The microballoons generally have crush strengths of 1000-8,000 psig (and all values and ranges therebetween), and typically microballoons have crush strengths of 1500-6000 psig crush strength can be used. Degradable aluminum alloys, zinc alloys, and magnesium alloys, as well as degradable polymers (elastomers, PVA, PLA and PGA and their mixtures, PEG, cellulistic polymers, nylon (particularly with CaO, Na.sub.2O, BaSO.sub.4, NH.sub.3SO.sub.4 or other high or low PH creating addition on contact with water) are particularly useful in creating a degradable variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material.

[0162] As illustrated in FIG. 7, after local deformation of the variable stiffness degradable deformable metallic material formed of a degradable aluminum alloy having microballoons dispersed in the degradable aluminum alloy, the strength (and stiffness) increase dramatically, thereby inhibiting or preventing further deformation without the addition of much higher forces. This increase in strength and/or stiffness is the result of the crushing of the microballoons, the resulting reduction of porosity, and density increase of the variable stiffness degradable deformable metallic material. In this manner, the variable stiffness degradable deformable metallic material can “seat-in” to complex cavities and then resist further deformation, becoming a solid plug or seal with reduced leakage. Proper design of a sealing surface can be envisioned by one skilled in the art. The density of a variable stiffness degradable deformable metallic material in the form of a divertor (e.g., [glass, ceramic, and/or carbon microballoon]-Mg diverter or [glass, ceramic, and/or carbon microballoon]-Mg frac ball) can be 0.95-1.4 g/cc. As can be appreciated, a divertor or frac ball formed of variable stiffness elastomeric composite can also have similar densities. In additional or alternatively, the diverter or frac ball can include a central cavity that constitutes no more than 70 vol. % of the diverter or frac ball, and typically about 20-50 vol % of the diverter or frac ball, and more typically 30-50 vol % of the diverter or frac ball to control the density to 1.02-1.15 g/cc to match the density of the completion fluid or brine. The size of the central cavity and/or volume percent of the microballoons in the diverter or frac ball can be selected such that the density of the diverter or frac ball is the same or similar to the sand or proppant-water mixture density used in the completion process, such that flow of the diverter or frac balls matches the flow of the completion fluid.

[0163] To facilitate understanding of several non-limiting aspects of the disclosure, the following non-limiting examples are provided.

[0164] For loss control applications, a larger flexible sheet or foil can be used. Typical loss control materials include rags, etc., which are often tied into a knot and added. A good shape for the variable stiffness elastomeric composite or variable stiffness degradable deformable metallic material to form seals while being pumpable is a V or conical shape, with or without tails, that follow fluid flow but seat and are retained in a fracture.

EXAMPLE 1

[0165] An elastomeric dissolvable composite ball formed of about 50 vol. % soda lime glass microballoons having a particle size of 30 μm and having a density of 0.23 g/cc was bonded together with 20 vol. % powdered nitrile-butadiene rubber (NBR) particles and 30 vol. % polyvinyl alcohol. The elastomeric dissolvable composite ball had a size of ⅞ in. diameter and an overall density of 0.95 g/cc. The elastomeric dissolvable composite ball was tested to hold 1500 psi for two hours and, as illustrated in Table 1, loses 50% weight over a period of 72 hours in tap water at 51.7° C., and which left particles in the range of 30-100 μm.

EXAMPLE 2

[0166] An elastomeric dissolvable composite ball formed of about 60 vol. % soda lime glass micro balloons with a particle size of 30 micron, having a density of 0.23 g/cc was bonded together with 20 vol. % powdered NBR particles and 20 vol. % polyvinyl alcohol. The elastomeric dissolvable composite ball had a size of ⅞ in. diameter and an overall density of 0.80 g/cc. The elastomeric composite ball was tested to hold 1500 psi for four hours and, as illustrated in Table 1, loses 50% weight over a period of 96 hours in tap water at 51.7° C., and which left particles in the range of 30-100 μm.

TABLE-US-00001 TABLE 1 Initial Wt. 3 hrs. 6 hrs. 24 hrs. 48 hrs. 72 hrs. Example (g) (g) (g) (g) (g) (g) 1 5.583 5.790 5.340 4.956 4.709 2.970 2 5.712 5.986 6.150 5.541 4.616 2.907

EXAMPLE 3

[0167] An elastomeric dissolvable composite ball formed of about 60 vol. % soda lime glass microballoons having particle size of 20 μm and having a density of 0.46 g/cc was bonded together with 20 vol. % powdered NBR particles and 20 vol. % polyvinyl alcohol. The elastomeric dissolvable composite ball had a size of ⅞ in. diameter and an overall density of 1.05 g/cc. This elastomeric composite ball was tested to hold 1500 psi for 0.5 hours, as illustrated in FIG. 8, and loses 50% weight over a period of 24 hours in tap water at 51.7° C., and which left particles in the range of 50-70 μm. The partially degraded ball is illustrated in FIG. 9.

EXAMPLE 4

[0168] A degradable magnesium alloy is used as a binder with 40 vol. % hollow ceramic microballoons (fillite 150 cenospheres), having an initial crush strength of 3500 psig and a density of 1.35 g/cc via squeeze casting into a microballoon-Mg powder preform at 500 psig. The microballoon-Mg powder was then extruded to form rods. Thereafter, the extruded rods were machined into balls.

[0169] Suitable degradable cast magnesium composites that can be used include degradable cast magnesium composites disclosed in U.S. Pat. Nos. 9,757,796; 9,903,010; 10,329,653 and US Pub. No. 2019/0054523, which are incorporated herein by reference. The dissolvable cast magnesium composite generally includes greater than 50 wt. % magnesium and about 0.5-49.5 wt. % of additive (e.g., aluminum, zinc, tin, beryllium, boron carbide, copper, nickel, bismuth, cobalt, titanium, manganese, potassium, sodium, antimony, indium, strontium, barium, silicon, lithium, silver, gold, cesium, gallium, calcium, iron, lead, mercury, arsenic, rare earth metals [e.g., yttrium, lanthanum, samarium, europium, gadolinium, terbium, dysprosium, holmium, ytterbium, etc.] and zirconium). Generally, the dissolvable cast magnesium composite has a magnesium content of at least 85 wt. %. In one non-limiting embodiment, there is provided a magnesium composite that is over 50 wt. % magnesium and about 0.05-49.5 wt. % nickel (and all values or ranges therebetween) is added to the magnesium or magnesium alloy to form intermetallic magnesium-nickel as a galvanically-active in situ precipitate (e.g., 0.05-23.5 wt. % nickel, 0.01-5 wt. % nickel, 3-7 wt. % nickel, 7-10 wt. % nickel, or 10-24.5 wt. % nickel). In another non-limiting embodiment, there is provided a magnesium composite that is over 50 wt. % magnesium and about 0.05-49.5 wt. % copper (and all values or ranges therebetween) is added to the magnesium or magnesium alloy to form intermetallic magnesium-copper as a galvanically-active in situ precipitate (e.g., 0.01-5 wt. % copper, 0.5-15 wt. % copper, 15-35 wt. % copper, 0.01-20 wt. % copper). In another non-limiting embodiment, there is provided a magnesium composite that is over 50 wt. % magnesium and about 0.05-49.5 wt. % of an additive (and all values or ranges therebetween) (e.g., calcium, copper, nickel, cobalt, bismuth, silver, gold, lead, tin, antimony, indium, arsenic, mercury, gallium and rare earth metals). The degradable cast magnesium composites generally has a dissolution rate of at least 5 mg/cm.sup.2-hr. in 3% KCl at 90° C. (e.g., 40-325 mg/cm.sup.2/hr. in 3 wt. % KCl water mixture at 90° C., 50-325 mg/cm.sup.2/hr. in 3 wt. % KCl water mixture at 90° C.; 75-325 mg/cm.sup.2/hr. in 3 wt. % KCl water mixture at 90° C.; 84-325 mg/cm.sup.2/hr. in 3 wt. % KCl water mixture at 90° C.; 100-325 mg/cm.sup.2/hr. in 3 wt. % KCl water mixture at 90° C.; 110-325 mg/cm.sup.2/hr. in 3 wt. % KCl water mixture at 90° C.). The degradable cast magnesium composites generally have a dissolution rate of up to 1 mg/cm.sup.2/hr. in 3 wt. % KCl water mixture at 20° C. The degradable cast magnesium composites generally include no more than 10 wt. % aluminum.

[0170] Suitable degradable powdered metallurgy magnesium composites formed from compression and/or sintering include the degradable magnesium composites disclosed in US Pub. No. 2007/0181224 and U.S. Pat. No. 8,663,401, which are incorporated herein by reference. For example, the degradable powdered metallurgy magnesium composites can include one or more reactive metals selected from calcium, magnesium, and aluminum, and one or more secondary metals such as lithium, gallium, indium, zinc, bismuth, calcium, magnesium, tin, copper, silver, cadmium, and lead.

[0171] A plurality of 3.4 in. diverter balls was inserted into a flowing completion fluid containing sand and allowed to reach the completion zone. The near neutral buoyancy of the diverter balls followed the main flow of the completion fluid and then seated into the opening in the well formation. The diverter balls locally crush at the edges to partially conform to the eroded hole geometry in the well formation and diverted 80-95 vol. % of the flow of the completion fluid to other openings in the well formation. By periodically inserting additional diverter balls in the completion fluid, a dramatic increase in fracture uniformity and sand placement was achieved in the well formation. After stimulation of the well formation was completed, a gelbreaker, buffered pH addition (e.g., monosodium sulfate, etc.) etc., was added to the completion fluid, which resulted in the complete solubilization of the magnesium of the diverter balls to produce a clear solution that did not degrade the formation geology. In one non-limiting embodiment, a delay release gelbreaker (e.g., encapsulated acid, encapsulated xylanase/hemicellulase complex, encapsulated ammonium persulfate, encapsulated potassium persulfate, encapsulated sodium persulfate, encapsulated sodium bromate, etc.) can be used to remove the seals after an engineered time by controlling fluid conditions.

[0172] After performing their function, the magnesium based diverters are removed by further exposure to a completion fluid or breaker, which can include fresh, brackish water or saline solutions, or with breaker fluids, such as those with a reduced or buffered pH that is generally less than about 7, and typically below 5.5-6 pH, and more typically less than about 4 pH. The magnesium alloy and degradation characteristics can be, and usually are, matched to the fluid and wellbore temperature conditions.

EXAMPLE 5

[0173] A degradable magnesium alloy is formed into a ¾ in. hollow ball fabricated to have near neutral buoyancy in drilling mud. The ball is coated with a degradable plastic or elastomeric coating having a thickness of about 0.1 in. The resultant ball is added to mud and circulated into a formation, where it becomes lodged in a fracture. Additional degradable diverter material can be added in the form of magnesium metal turnings and degradable elastomer or polymeric powders. Additional balls and sealant materials can be added and combined to seal multiple fractures or open areas to reduce pumping losses by at least 75%. After completion of drilling activities, an active agent that includes a pH-lowering gelbreaker (e.g. 5 vol. % HCl or green acid solution, etc.) is added in an encapsulated or unencapsulated form to the completion fluid and circulated through the wellbore formation. The interaction of the active fluid solubilizes the degradable component to create a clean/clear fluid with reduced impact on geologic formation properties.

[0174] It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the constructions set forth without departing from the spirit and scope of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. The disclosure has been described with reference to preferred and alternate embodiments. Modifications and alterations will become apparent to those skilled in the art upon reading and understanding the detailed discussion of the disclosure provided herein. This disclosure is intended to include all such modifications and alterations insofar as they come within the scope of the present disclosure. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the disclosure herein described and all statements of the scope of the disclosure, which, as a matter of language, might be said to fall there between. The disclosure has been described with reference to the preferred embodiments. These and other modifications of the preferred embodiments as well as other embodiments of the disclosure will be obvious from the disclosure herein, whereby the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.