Formation treatment system and method

A formation treatment system includes an annulus spanning member having one or more openings therein, the one or more openings incorporating a degradable material. A tubular having one or more ports therein in fluid communication with the one or more openings. A sleeve capable of isolating or communicating the one or more ports with an ID of the tubular. A method for effecting precision formation treatment is included.

BACKGROUND

In downhole industries such as hydrocarbon recovery, and Carbon Dioxide sequestration, for example, formation treatments such as “fracing” and “acidizing” are well-known parts of downhole processes designed to increase permeability in or stimulate a formation. In general, a fracing process includes the employment of hyperbaric pressures applied from a surface location and directed through ports in a tubing string. The increased pressure while it does indeed result in formation fracture does not necessarily fracture the formation in optimum or even very controlled locations. Acidizing is similarly less than optimumly targeted. Since fractures and acidizing points can dramatically improve the efficiency of a downhole completion, the art will well receive alternate formation treatment systems and methods.

SUMMARY

A formation treatment system includes an annulus spanning member having one or more openings therein, the one or more openings initially incorporating a degradable material; a tubular having one or more ports therein in fluid communication with the one or more openings; and a sleeve capable of isolating or communicating the one or more ports with an ID of the tubular.

A method for effecting precision formation treatment including setting an annulus spanning member in a formation to bring one or more openings in the annulus spanning member proximate a formation wall, the one or more openings initially incorporating a degradable material; revealing one or more ports in a tubular member; communicating a tubular ID to the one or more openings in the annulus spanning member; applying fluid through the tubular ID, the fluid degrading the degradable material and removing the degradable material from the one or more openings; and directing the fluid to the formation through the one or more openings.

A method for effecting precision formation treatment including deploying a plug member to a formation treatment system includes an annulus spanning member having one or more openings therein, the one or more openings initially incorporating a degradable material; a tubular having one or more ports therein in fluid communication with the one or more openings; and a sleeve capable of isolating or communicating the one or more ports with an ID of the tubular; setting the annulus spanning member in a formation to bring one or more openings in the annulus spanning member proximate a formation wall by pressurizing a chamber defined by the annulus spanning member and the tubular; revealing one or more ports in the tubular member by moving the sleeve pursuant to pressure upon the plug on a seat in the sleeve; communicating a tubular ID to the one or more openings in the annulus spanning member; applying a fluid through the tubular ID, the fluid degrading the degradable material and removing the degradable material from the one or more openings; and directing the fluid to the formation through the one or more openings.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, a first embodiment of a formation treatment system10as disclosed herein is illustrated. The system10includes an annulus spanning member12(in a run-in or resting position) that may be a deformable element and may in some embodiments also act as a seal. The member12includes one or more openings14through which at least pressure is transmittable at selected times. It may however be desirable to plug the one or more holes at one or more times during the life cycle of the system. More information will be provided on this point later in this disclosure. In one embodiment the member12will include pips16that extend radially outwardly of a body18of the member12regardless of the position of the member12. Member12is positioned radially outwardly of a tubular20that includes one or more ports22. Further is a sleeve24acting as a valve in combination with the tubular20. The sleeve includes one or more passageways26extending radially therethrough. The sleeve24is translationally supported within the tubular20such that the one or more passageways26are alignable and misalignable with the one or more ports22.

In use, a first action is to cause the annulus spanning member12to span an annulus28between the system10and a formation30in which the system10is disposed. This can be done in a number of ways, some of which result in a compressive load being placed axially of the member12, resulting in its deformation radially outwardly as shown inFIG. 2. Also notable inFIG. 2is that the embodiment illustrated includes pips16and those pips16are embedded in the formation. This serves to segregate an annular space32in fluid connection with the one or more openings14, the one or more ports22and the one or more passageways26to provide a fluid conduit from the formation30to an inside dimension (“ID”) of the system10. The pips, then, assist in directing fluid pressure to the target area. The segregation of the area is also useful for purposes such as matrix acidizing since due to the confined nature of application, less acid would be needed to effect the desired result of formation stimulation, for example.

Those of skill in the art will recognize the system will be a part of a string34and the “ID” will be fluidically accessible to surface for pressurization. As illustrated inFIG. 2, the sleeve24has already been shifted to align the passageways26with the ports22and the openings14. It is to be assumed that somewhere downhole of the system10the ID is plugged so that applied pressure from uphole of the system10finds an exit from the string only at or at least primarily at the openings14. Because of this condition, applied pressure or acid is directed to a very small portion of the formation and fracture initiation is very likely to occur there and acid treatment will certainly be applied directly there. Accordingly, through use of the system and method hereof, great precision in fracture initiation or acidizing is effected.

In another embodiment, referring toFIGS. 3-5, a system110is illustrated that is similar to that ofFIGS. 1 and 2but is configured for use in situations where one or more fractures are planned or areas for acid treatment along a borehole are planned. More specifically, the system110employs a ball or other droppable or pumpable plug member140can be used to plug a particular system110to treat a certain target spot and then another plug140can be used for a next target spot and so on for as many systems110as are employed in a particular borehole.

The system110includes a member112similar to the member12ofFIGS. 1 and 2but that is actuated differently. The member112is configured to create a chamber142with tubing120upon which the member112may slide. The member112and tubing120are sealed to one another by o-rings144or equivalent. An actuation port146is located through the tubing120to allow pressure to be increased in the chamber142for actuation of the member112.

The system110further includes in one embodiment a one way movement configuration148, which in one embodiment may be a body lock ring or other ratcheting type configuration. The configuration148functions between the member112and tubing120to allow for the member112to move downhole relative to the tubing120(as illustrated but it is to be understood that this could be configured oppositely). The purpose and function of the configuration148is to accept movement imposed by the chamber142and then deny movement of the member112to a relaxed position after the force imposed by the chamber148is withdrawn.

System110further includes one or more openings114and one or more ports122. The ports122and openings114are initially fluidly isolated from the ID of the system110by a sleeve150. In one embodiment, the sleeve150includes an optional plug seat152receptive of a plug140as illustrated. The sleeve includes seals154that straddle the ports122during a nonoperational position of the system110. Finally the system110includes a release mechanism156which in some embodiments may be a shear arrangement such as one or more shear screws.

It is to be appreciated that the one or more openings14and114in annulus spanning members12and112can form a jet of fluid therethrough simply because the openings are relatively small in dimension. An even more effective jet can be formed if individual openings are configured through the thickness of the material of the annulus spanning member in a conical manner. The openings so configured would then act to some degree as nozzles. An enlarged schematic view of such is included asFIG. 6. Such a jet of fluid will aid in the initiation of a fracture by disrupting a surface of the formation through fluid erosion.

During use of the system110, the system is run to a target location in a borehole and then a plug140is dropped or pumped to the location of the system110. Upon seating in the seat152, the plug140prevents fluid in the ID of the string from flowing past the seat152. Referring toFIGS. 3 and 4, fluid pressure accordingly builds on an uphole side of the plug140(could be reversed for downhole if desired but must be upstream of the fluid flow). Increasing pressure acts upon chamber142to increase a dimension thereof that is longitudinal of the system110. Increasing this dimension of the chamber142causes the member112to buckle radially outwardly toward and ultimately, in some embodiments, into contact with the formation30. Referring toFIG. 5, once a threshold pressure is reached at which it is expected the member112will be fully deployed, the release member156releases and the sleeve150moves downhole (downstream) thereby opening the one or more ports122to allow the application of pressure to reach the openings114and the formation30. Note that a shoulder160is provided to stop movement of the sleeve150after the one or more ports122are revealed. At this point the pressure can be increased to fracing pressure and the fracture will tend to initiate between pips116as in the embodiment ofFIGS. 1 and 2(or as noted above, acid can be applied to the formation between the pips. The system110can work with other systems110further upstream since after the treatment occurs as stated, flow is restored sufficiently to land another plug140at a more uphole sleeve150and the process as described again is repeated.

The embodiments ofFIGS. 6A and 6Bshow openings14and114in the annulus spanning member incorporating a degradable material200in the form of a barrier, block, or layer at least partially blocking or obstructing the openings14and/or114. Material200is initially at least partially blocking/obstructing the openings14and114. The material200will then corrode, dissolve, degrade, or otherwise be removed based upon exposure to a fluid in contact therewith. Generally, as used herein, the term “degradable” shall be used to mean able to corrode, dissolve, degrade, disperse, or otherwise be removed or eliminated, while “degrading” or “degrade” will likewise describe that the material is corroding, dissolving, dispersing, or otherwise being removed or eliminated. Any other form of “degrade” shall incorporate this meaning. The fluid may be a natural borehole fluid such as water, oil, etc. or may be a fluid added to the borehole for the specific purpose of degrading the material200. Material200may be constructed of a number of materials that are degradable as noted above, but one embodiment in particular utilizes a high degradable magnesium based material having a selectively tailorable degradation rate and or yield strength. The material itself is discussed in detail later in this disclosure. This material exhibits exceptional strength while intact and will yet easily degrades in a controlled manner and selectively short time frame. The material isdegradable in water, water-based mud, downhole brines or acid, for example, at a selected rate as desired (as noted above). In addition, surface irregularities to increase a surface area of the material200that is exposed to the degradation fluid such as grooves, corrugations, depressions, etc. may be used. During degradation of the material200, the openings14or114may be opened, unblocked, created, and/or enlarged. Because the material disclosed above can be tailored to completely degrade the material in about 4 to 10 minutes, the openings can be opened, unblocked, created, and/or enlarged virtually immediately as necessary. Even if initially completely blocked by degradable material200, the openings14and114are still considered and referred to as openings because the degradable material is intended to be removed.

The materials200in the openings14and114as described herein are lightweight, high-strength metallic materials that may be used in a wide variety of applications and application environments, including use in various borehole environments to make various selectably and controllably disposable or degradable lightweight, high-strength downhole tools or other downhole components, as well as many other applications for use in both durable and disposable or degradable articles. These lightweight, high-strength and selectably and controllably degradable materials include fully-dense, sintered powder compacts formed from coated powder materials that include various lightweight particle cores and core materials having various single layer and multilayer nanoscale coatings. These powder compacts are made from coated metallic powders that include various electrochemically-active (e.g., having relatively higher standard oxidation potentials) lightweight, high-strength particle cores and core materials, such as electrochemically active metals, that are dispersed within a cellular nanomatrix formed from the various nanoscale metallic coating layers of metallic coating materials, and are particularly useful in wellbore applications. These powder compacts provide a unique and advantageous combination of mechanical strength properties, such as compression and shear strength, low density and selectable and controllable corrosion properties, particularly rapid and controlled dissolution in various wellbore fluids. For example, the particle core and coating layers of these powders may be selected to provide sintered powder compacts suitable for use as high strength engineered materials having a compressive strength and shear strength comparable to various other engineered materials, including carbon, stainless and alloy steels, but which also have a low density comparable to various polymers, elastomers, low-density porous ceramics and composite materials. As yet another example, these powders and powder compact materials may be configured to provide a selectable and controllable degradation or disposal in response to a change in an environmental condition, such as a transition from a very low dissolution rate to a very rapid dissolution rate in response to a change in a property or condition of a wellbore proximate an article formed from the compact, including a property change in a wellbore fluid that is in contact with the powder compact. The selectable and controllable degradation or disposal characteristics described also allow the dimensional stability and strength of articles, such as wellbore tools or other components, made from these materials to be maintained until they are no longer needed, at which time a predetermined environmental condition, such as a wellbore condition, including wellbore fluid temperature, pressure or pH value, may be changed to promote their removal by rapid dissolution. These coated powder materials and powder compacts and engineered materials formed from them, as well as methods of making them, are described further below.

Referring toFIGS. 7-12, further specifics regarding material200can be gleaned. InFIG. 7, a metallic powder210includes a plurality of metallic, coated powder particles212. Powder particles212may be formed to provide a powder210, including free-flowing powder, that may be poured or otherwise disposed in all manner of forms or molds (not shown) having all manner of shapes and sizes and that may be used to fashion precursor powder compacts and powder compacts400(FIGS. 9 and 10), as described herein, that may be used as, or for use in manufacturing, various articles of manufacture, including various wellbore tools and components.

Each of the metallic, coated powder particles212of powder210includes a particle core214and a metallic coating layer216disposed on the particle core214. The particle core214includes a core material218. The core material218may include any suitable material for forming the particle core214that provides powder particle212that can be sintered to form a lightweight, high-strength powder compact400having selectable and controllable dissolution characteristics. Suitable core materials include electrochemically active metals having a standard oxidation potential greater than or equal to that of Zn, including as Mg, Al, Mn or Zn or a combination thereof. These electrochemically active metals are very reactive with a number of common wellbore fluids, including any number of ionic fluids or highly polar fluids, such as those that contain various chlorides. Examples include fluids comprising potassium chloride (KCl), hydrochloric acid (HCl), calcium chloride (CaCl2), calcium bromide (CaBr2) or zinc bromide (ZnBr2). Core material218may also include other metals that are less electrochemically active than Zn or non-metallic materials, or a combination thereof. Suitable non-metallic materials include ceramics, composites, glasses or carbon, or a combination thereof. Core material218may be selected to provide a high dissolution rate in a predetermined wellbore fluid, but may also be selected to provide a relatively low dissolution rate, including zero dissolution, where dissolution of the nanomatrix material causes the particle core214to be rapidly undermined and liberated from the particle compact at the interface with the wellbore fluid, such that the effective rate of dissolution of particle compacts made using particle cores214of these core materials218is high, even though core material218itself may have a low dissolution rate, including core materials220that may be substantially insoluble in the wellbore fluid.

With regard to the electrochemically active metals as core materials218, including Mg, Al, Mn or Zn, these metals may be used as pure metals or in any combination with one another, including various alloy combinations of these materials, including binary, tertiary, or quaternary alloys of these materials. These combinations may also include composites of these materials. Further, in addition to combinations with one another, the Mg, Al, Mn or Zn core materials218may also include other constituents, including various alloying additions, to alter one or more properties of the particle cores214, such as by improving the strength, lowering the density or altering the dissolution characteristics of the core material218.

Among the electrochemically active metals, Mg, either as a pure metal or an alloy or a composite material, is particularly useful, because of its low density and ability to form high-strength alloys, as well as its high degree of electrochemical activity, since it has a standard oxidation potential higher than Al, Mn or Zn. Mg alloys include all alloys that have Mg as an alloy constituent. Mg alloys that combine other electrochemically active metals, as described herein, as alloy constituents are particularly useful, including binary Mg—Zn, Mg—Al and Mg—Mn alloys, as well as tertiary Mg—Zn—Y and Mg—Al—X alloys, where X includes Zn, Mn, Si, Ca or Y, or a combination thereof. These Mg—Al—X alloys may include, by weight, up to about 85% Mg, up to about 15% Al and up to about 5% X. Particle core214and core material218, and particularly electrochemically active metals including Mg, Al, Mn or Zn, or combinations thereof, may also include a rare earth element or combination of rare earth elements. As used herein, rare earth elements include Sc, Y, La, Ce, Pr, Nd or Er, or a combination of rare earth elements. Where present, a rare earth element or combinations of rare earth elements may be present, by weight, in an amount of about 5% or less.

Particle core214and core material218have a melting temperature (TP). As used herein, TPincludes the lowest temperature at which incipient melting or liquation or other forms of partial melting occur within core material218, regardless of whether core material218comprises a pure metal, an alloy with multiple phases having different melting temperatures or a composite of materials having different melting temperatures.

Particle cores214may have any suitable particle size or range of particle sizes or distribution of particle sizes. For example, the particle cores214may be selected to provide an average particle size that is represented by a normal or Gaussian type unimodal distribution around an average or mean, as illustrated generally inFIG. 7. In another example, particle cores214may be selected or mixed to provide a multimodal distribution of particle sizes, including a plurality of average particle core sizes, such as, for example, a homogeneous bimodal distribution of average particle sizes. The selection of the distribution of particle core size may be used to determine, for example, the particle size and interparticle spacing215of the particles212of powder210. In an exemplary embodiment, the particle cores214may have a unimodal distribution and an average particle diameter of about 5 μm to about 300 μm, more particularly about 80 μm to about 120 μm, and even more particularly about 100 μm.

Particle cores214may have any suitable particle shape, including any regular or irregular geometric shape, or combination thereof. In an exemplary embodiment, particle cores214are substantially spheroidal electrochemically active metal particles. In another exemplary embodiment, particle cores214are substantially irregularly shaped ceramic particles. In yet another exemplary embodiment, particle cores214are carbon or other nanotube structures or hollow glass microspheres.

Each of the metallic, coated powder particles212of powder210also includes a metallic coating layer216that is disposed on particle core214. Metallic coating layer216includes a metallic coating material220. Metallic coating material220gives the powder particles212and powder210its metallic nature. Metallic coating layer216is a nanoscale coating layer. In an exemplary embodiment, metallic coating layer216may have a thickness of about 25 nm to about 2500 nm. The thickness of metallic coating layer216may vary over the surface of particle core214, but will preferably have a substantially uniform thickness over the surface of particle core214. Metallic coating layer216may include a single layer, as illustrated inFIG. 7, or a plurality of layers as a multilayer coating structure. In a single layer coating, or in each of the layers of a multilayer coating, the metallic coating layer216may include a single constituent chemical element or compound, or may include a plurality of chemical elements or compounds. Where a layer includes a plurality of chemical constituents or compounds, they may have all manner of homogeneous or heterogeneous distributions, including a homogeneous or heterogeneous distribution of metallurgical phases. This may include a graded distribution where the relative amounts of the chemical constituents or compounds vary according to respective constituent profiles across the thickness of the layer. In both single layer and multilayer coatings216, each of the respective layers, or combinations of them, may be used to provide a predetermined property to the powder particle212or a sintered powder compact formed therefrom. For example, the predetermined property may include the bond strength of the metallurgical bond between the particle core214and the coating material220; the interdiffusion characteristics between the particle core214and metallic coating layer216, including any interdiffusion between the layers of a multilayer coating layer216; the interdiffusion characteristics between the various layers of a multilayer coating layer216; the interdiffusion characteristics between the metallic coating layer216of one powder particle and that of an adjacent powder particle212; the bond strength of the metallurgical bond between the metallic coating layers of adjacent sintered powder particles212, including the outermost layers of multilayer coating layers; and the electrochemical activity of the coating layer216.

Metallic coating layer216and coating material220have a melting temperature (TC). As used herein, TCincludes the lowest temperature at which incipient melting or liquation or other forms of partial melting occur within coating material220, regardless of whether coating material220comprises a pure metal, an alloy with multiple phases each having different melting temperatures or a composite, including a composite comprising a plurality of coating material layers having different melting temperatures.

Metallic coating material220may include any suitable metallic coating material220that provides a sinterable outer surface221that is configured to be sintered to an adjacent powder particle212that also has a metallic coating layer216and sinterable outer surface221. In powders210that also include second or additional (coated or uncoated) particles232, as described herein, the sinterable outer surface221of metallic coating layer216is also configured to be sintered to a sinterable outer surface221of second particles232. In an exemplary embodiment, the powder particles212are sinterable at a predetermined sintering temperature (TS) that is a function of the core material218and coating material220, such that sintering of powder compact400is accomplished entirely in the solid state and where TSis less than TPand TC. Sintering in the solid state limits particle core214/metallic coating layer216interactions to solid state diffusion processes and metallurgical transport phenomena and limits growth of and provides control over the resultant interface between them. In contrast, for example, the introduction of liquid phase sintering would provide for rapid interdiffusion of the particle core214/metallic coating layer216materials and make it difficult to limit the growth of and provide control over the resultant interface between them, and thus interfere with the formation of the desirable microstructure of particle compact400as described herein.

In an exemplary embodiment, core material218will be selected to provide a core chemical composition and the coating material220will be selected to provide a coating chemical composition and these chemical compositions will also be selected to differ from one another. In another exemplary embodiment, the core material218will be selected to provide a core chemical composition and the coating material220will be selected to provide a coating chemical composition and these chemical compositions will also be selected to differ from one another at their interface. Differences in the chemical compositions of coating material220and core material218may be selected to provide different dissolution rates and selectable and controllable dissolution of powder compacts400that incorporate them making them selectably and controllably dissolvable. This includes dissolution rates that differ in response to a changed condition in the wellbore, including an indirect or direct change in a wellbore fluid. In an exemplary embodiment, a powder compact400formed from powder210having chemical compositions of core material218and coating material220that make compact400is selectably dissolvable in a wellbore fluid in response to a changed wellbore condition that includes a change in temperature, change in pressure, change in flow rate, change in pH or change in chemical composition of the wellbore fluid, or a combination thereof. The selectable dissolution response to the changed condition may result from actual chemical reactions or processes that promote different rates of dissolution, but also encompass changes in the dissolution response that are associated with physical reactions or processes, such as changes in wellbore fluid pressure or flow rate.

As illustrated inFIGS. 7 and 8, particle core214and core material218and metallic coating layer216and coating material220may be selected to provide powder particles212and a powder210that is configured for compaction and sintering to provide a powder compact400that is lightweight (i.e., having a relatively low density), high-strength and is selectably and controllably removable from a wellbore in response to a change in a wellbore property, including being selectably and controllably dissolvable in an appropriate wellbore fluid, including various wellbore fluids as disclosed herein. Powder compact400includes a substantially-continuous, cellular nanomatrix416of a nanomatrix material420having a plurality of dispersed particles414dispersed throughout the cellular nanomatrix416. The substantially-continuous cellular nanomatrix416and nanomatrix material420formed of sintered metallic coating layers216is formed by the compaction and sintering of the plurality of metallic coating layers216of the plurality of powder particles212. The chemical composition of nanomatrix material420may be different than that of coating material220due to diffusion effects associated with the sintering as described herein. Powder metal compact400also includes a plurality of dispersed particles414that comprise particle core material418. Dispersed particle cores414and core material418correspond to and are formed from the plurality of particle cores214and core material218of the plurality of powder particles212as the metallic coating layers216are sintered together to form nanomatrix416. The chemical composition of core material418may be different than that of core material218due to diffusion effects associated with sintering as described herein.

As used herein, the use of the term substantially-continuous cellular nanomatrix416does not connote the major constituent of the powder compact, but rather refers to the minority constituent or constituents, whether by weight or by volume. This is distinguished from most matrix composite materials where the matrix comprises the majority constituent by weight or volume. The use of the term substantially-continuous, cellular nanomatrix is intended to describe the extensive, regular, continuous and interconnected nature of the distribution of nanomatrix material420within powder compact400. As used herein, “substantially-continuous” describes the extension of the nanomatrix material throughout powder compact400such that it extends between and envelopes substantially all of the dispersed particles414. Substantially-continuous is used to indicate that complete continuity and regular order of the nanomatrix around each dispersed particle414is not required. For example, defects in the coating layer216over particle core214on some powder particles212may cause bridging of the particle cores214during sintering of the powder compact400, thereby causing localized discontinuities to result within the cellular nanomatrix416, even though in the other portions of the powder compact the nanomatrix is substantially continuous and exhibits the structure described herein. As used herein, “cellular” is used to indicate that the nanomatrix defines a network of generally repeating, interconnected, compartments or cells of nanomatrix material420that encompass and also interconnect the dispersed particles414. As used herein, “nanomatrix” is used to describe the size or scale of the matrix, particularly the thickness of the matrix between adjacent dispersed particles414. The metallic coating layers that are sintered together to form the nanomatrix are themselves nanoscale thickness coating layers. Since the nanomatrix at most locations, other than the intersection of more than two dispersed particles414, generally comprises the interdiffusion and bonding of two coating layers216from adjacent powder particles212having nanoscale thicknesses, the matrix formed also has a nanoscale thickness (e.g., approximately two times the coating layer thickness as described herein) and is thus described as a nanomatrix. Further, the use of the term dispersed particles414does not connote the minor constituent of powder compact400, but rather refers to the majority constituent or constituents, whether by weight or by volume. The use of the term dispersed particle is intended to convey the discontinuous and discrete distribution of particle core material418within powder compact400.

Powder compact400may have any desired shape or size, including that of a cylindrical billet or bar that may be machined or otherwise used to form useful articles of manufacture, including various wellbore tools and components. The pressing used to form precursor powder compact and sintering and pressing processes used to form powder compact400and deform the powder particles212, including particle cores214and coating layers216, to provide the full density and desired macroscopic shape and size of powder compact400as well as its microstructure. The microstructure of powder compact400includes an equiaxed configuration of dispersed particles414that are dispersed throughout and embedded within the substantially-continuous, cellular nanomatrix416of sintered coating layers. This microstructure is somewhat analogous to an equiaxed grain microstructure with a continuous grain boundary phase, except that it does not require the use of alloy constituents having thermodynamic phase equilibria properties that are capable of producing such a structure. Rather, this equiaxed dispersed particle structure and cellular nanomatrix416of sintered metallic coating layers216may be produced using constituents where thermodynamic phase equilibrium conditions would not produce an equiaxed structure. The equiaxed morphology of the dispersed particles414and cellular network416of particle layers results from sintering and deformation of the powder particles212as they are compacted and interdiffuse and deform to fill the interparticle spaces215(FIG. 7). The sintering temperatures and pressures may be selected to ensure that the density of powder compact400achieves substantially full theoretical density.

In an exemplary embodiment as illustrated inFIGS. 7 and 8, dispersed particles414are formed from particle cores214dispersed in the cellular nanomatrix416of sintered metallic coating layers216, and the nanomatrix416includes a solid-state metallurgical bond417or bond layer419, as illustrated schematically inFIG. 9, extending between the dispersed particles414throughout the cellular nanomatrix416that is formed at a sintering temperature (TS), where TSis less than TCand TP. As indicated, solid-state metallurgical bond417is formed in the solid state by solid-state interdiffusion between the coating layers216of adjacent powder particles212that are compressed into touching contact during the compaction and sintering processes used to form powder compact400, as described herein. As such, sintered coating layers216of cellular nanomatrix416include a solid-state bond layer419that has a thickness (t) defined by the extent of the interdiffusion of the coating materials220of the coating layers216, which will in turn be defined by the nature of the coating layers216, including whether they are single or multilayer coating layers, whether they have been selected to promote or limit such interdiffusion, and other factors, as described herein, as well as the sintering and compaction conditions, including the sintering time, temperature and pressure used to form powder compact400.

As nanomatrix416is formed, including bond417and bond layer419, the chemical composition or phase distribution, or both, of metallic coating layers216may change. Nanomatrix416also has a melting temperature (TM). As used herein, TMincludes the lowest temperature at which incipient melting or liquation or other forms of partial melting will occur within nanomatrix416, regardless of whether nanomatrix material420comprises a pure metal, an alloy with multiple phases each having different melting temperatures or a composite, including a composite comprising a plurality of layers of various coating materials having different melting temperatures, or a combination thereof, or otherwise. As dispersed particles414and particle core materials418are formed in conjunction with nanomatrix416, diffusion of constituents of metallic coating layers216into the particle cores214is also possible, which may result in changes in the chemical composition or phase distribution, or both, of particle cores214. As a result, dispersed particles414and particle core materials418may have a melting temperature (TDP) that is different than TP. As used herein, TDPincludes the lowest temperature at which incipient melting or liquation or other forms of partial melting will occur within dispersed particles414, regardless of whether particle core material418comprise a pure metal, an alloy with multiple phases each having different melting temperatures or a composite, or otherwise. Powder compact400is formed at a sintering temperature (TS), where TSis less than TC, TP, TMand TDP.

Dispersed particles414may comprise any of the materials described herein for particle cores214, even though the chemical composition of dispersed particles414may be different due to diffusion effects as described herein. In an exemplary embodiment, dispersed particles414are formed from particle cores214comprising materials having a standard oxidation potential greater than or equal to Zn, including Mg, Al, Zn or Mn, or a combination thereof, may include various binary, tertiary and quaternary alloys or other combinations of these constituents as disclosed herein in conjunction with particle cores214. Of these materials, those having dispersed particles414comprising Mg and the nanomatrix416formed from the metallic coating materials216described herein are particularly useful. Dispersed particles414and particle core material418of Mg, Al, Zn or Mn, or a combination thereof, may also include a rare earth element, or a combination of rare earth elements as disclosed herein in conjunction with particle cores214.

In another exemplary embodiment, dispersed particles414are formed from particle cores214comprising metals that are less electrochemically active than Zn or non-metallic materials. Suitable non-metallic materials include ceramics, glasses (e.g., hollow glass microspheres) or carbon, or a combination thereof, as described herein.

Dispersed particles414of powder compact400may have any suitable particle size, including the average particle sizes described herein for particle cores214.

Dispersed particles214may have any suitable shape depending on the shape selected for particle cores214and powder particles212, as well as the method used to sinter and compact powder210. In an exemplary embodiment, powder particles212may be spheroidal or substantially spheroidal and dispersed particles414may include an equiaxed particle configuration as described herein.

The nature of the dispersion of dispersed particles414may be affected by the selection of the powder210or powders210used to make particle compact400. In one exemplary embodiment, a powder210having a unimodal distribution of powder particle212sizes may be selected to form powder compact400and will produce a substantially homogeneous unimodal dispersion of particle sizes of dispersed particles414within cellular nanomatrix416, as illustrated generally inFIG. 8. In another exemplary embodiment, a plurality of powders210having a plurality of powder particles with particle cores214that have the same core materials218and different core sizes and the same coating material220may be selected and uniformly mixed as described herein to provide a powder210having a homogenous, multimodal distribution of powder particle212sizes, and may be used to form powder compact400having a homogeneous, multimodal dispersion of particle sizes of dispersed particles414within cellular nanomatrix416. Similarly, in yet another exemplary embodiment, a plurality of powders210having a plurality of particle cores214that may have the same core materials218and different core sizes and the same coating material220may be selected and distributed in a non-uniform manner to provide a non-homogenous, multimodal distribution of powder particle sizes, and may be used to form powder compact400having a non-homogeneous, multimodal dispersion of particle sizes of dispersed particles414within cellular nanomatrix416. The selection of the distribution of particle core size may be used to determine, for example, the particle size and interparticle spacing of the dispersed particles414within the cellular nanomatrix416of powder compacts400made from powder210.

Nanomatrix416is a substantially-continuous, cellular network of metallic coating layers216that are sintered to one another. The thickness of nanomatrix416will depend on the nature of the powder210or powders210used to form powder compact400, as well as the incorporation of any second powder230, particularly the thicknesses of the coating layers associated with these particles. In an exemplary embodiment, the thickness of nanomatrix416is substantially uniform throughout the microstructure of powder compact400and comprises about two times the thickness of the coating layers216of powder particles212. In another exemplary embodiment, the cellular network416has a substantially uniform average thickness between dispersed particles414of about 50 nm to about 5000 nm.

Nanomatrix416is formed by sintering metallic coating layers216of adjacent particles to one another by interdiffusion and creation of bond layer419as described herein. Metallic coating layers216may be single layer or multilayer structures, and they may be selected to promote or inhibit diffusion, or both, within the layer or between the layers of metallic coating layer216, or between the metallic coating layer216and particle core214, or between the metallic coating layer216and the metallic coating layer216of an adjacent powder particle, the extent of interdiffusion of metallic coating layers216during sintering may be limited or extensive depending on the coating thicknesses, coating material or materials selected, the sintering conditions and other factors. Given the potential complexity of the interdiffusion and interaction of the constituents, description of the resulting chemical composition of nanomatrix416and nanomatrix material420may be simply understood to be a combination of the constituents of coating layers216that may also include one or more constituents of dispersed particles414, depending on the extent of interdiffusion, if any, that occurs between the dispersed particles414and the nanomatrix416. Similarly, the chemical composition of dispersed particles414and particle core material418may be simply understood to be a combination of the constituents of particle core214that may also include one or more constituents of nanomatrix416and nanomatrix material420, depending on the extent of interdiffusion, if any, that occurs between the dispersed particles414and the nanomatrix416.

In an exemplary embodiment, the nanomatrix material420has a chemical composition and the particle core material418has a chemical composition that is different from that of nanomatrix material420, and the differences in the chemical compositions may be configured to provide a selectable and controllable dissolution rate, including a selectable transition from a very low dissolution rate to a very rapid dissolution rate, in response to a controlled change in a property or condition of the wellbore proximate the compact400, including a property change in a wellbore fluid that is in contact with the powder compact400, as described herein. Nanomatrix416may be formed from powder particles212having single layer and multilayer coating layers216. This design flexibility provides a large number of material combinations, particularly in the case of multilayer coating layers216, that can be utilized to tailor the cellular nanomatrix416and composition of nanomatrix material420by controlling the interaction of the coating layer constituents, both within a given layer, as well as between a coating layer216and the particle core214with which it is associated or a coating layer216of an adjacent powder particle212. Several exemplary embodiments that demonstrate this flexibility are provided below.

As illustrated inFIG. 9, in an exemplary embodiment, powder compact400is formed from powder particles212where the coating layer216comprises a single layer, and the resulting nanomatrix416between adjacent ones of the plurality of dispersed particles414comprises the single metallic coating layer216of one powder particle212, a bond layer419and the single coating layer216of another one of the adjacent powder particles212. The thickness (t) of bond layer419is determined by the extent of the interdiffusion between the single metallic coating layers216, and may encompass the entire thickness of nanomatrix416or only a portion thereof. In one exemplary embodiment of powder compact400formed using a single layer powder210, powder compact400may include dispersed particles414comprising Mg, Al, Zn or Mn, or a combination thereof, as described herein, and nanomatrix216may include Al, Zn, Mn, Mg, Mo, W, Cu, Fe, Si, Ca, Co, Ta, Re or Ni, or an oxide, carbide or nitride thereof, or a combination of any of the aforementioned materials, including combinations where the nanomatrix material420of cellular nanomatrix416, including bond layer419, has a chemical composition and the core material418of dispersed particles414has a chemical composition that is different than the chemical composition of nanomatrix material416. The difference in the chemical composition of the nanomatrix material420and the core material418may be used to provide selectable and controllable dissolution in response to a change in a property of a wellbore, including a wellbore fluid, as described herein. In a further exemplary embodiment of a powder compact400formed from a powder210having a single coating layer configuration, dispersed particles414include Mg, Al, Zn or Mn, or a combination thereof, and the cellular nanomatrix416includes Al or Ni, or a combination thereof.

As illustrated inFIG. 10, in another exemplary embodiment, powder compact400is formed from powder particles212where the coating layer216comprises a multilayer coating layer216having a plurality of coating layers, and the resulting nanomatrix416between adjacent ones of the plurality of dispersed particles414comprises the plurality of layers (t) comprising the coating layer216of one particle212, a bond layer419, and the plurality of layers comprising the coating layer216of another one of powder particles212. InFIG. 10, this is illustrated with a two-layer metallic coating layer216, but it will be understood that the plurality of layers of multi-layer metallic coating layer216may include any desired number of layers. The thickness (t) of the bond layer419is again determined by the extent of the interdiffusion between the plurality of layers of the respective coating layers216, and may encompass the entire thickness of nanomatrix416or only a portion thereof. In this embodiment, the plurality of layers comprising each coating layer216may be used to control interdiffusion and formation of bond layer419and thickness (t).

Sintered and forged powder compacts400that include dispersed particles414comprising Mg and nanomatrix416comprising various nanomatrix materials as described herein have demonstrated an excellent combination of mechanical strength and low density that exemplify the lightweight, high-strength materials disclosed herein. Examples of powder compacts400that have pure Mg dispersed particles414and various nanomatrices416formed from powders210having pure Mg particle cores214and various single and multilayer metallic coating layers216that include Al, Ni, W or Al2O3, or a combination thereof. These powders compacts400have been subjected to various mechanical and other testing, including density testing, and their dissolution and mechanical property degradation behavior has also been characterized as disclosed herein. The results indicate that these materials may be configured to provide a wide range of selectable and controllable corrosion or dissolution behavior from very low corrosion rates to extremely high corrosion rates, particularly corrosion rates that are both lower and higher than those of powder compacts that do not incorporate the cellular nanomatrix, such as a compact formed from pure Mg powder through the same compaction and sintering processes in comparison to those that include pure Mg dispersed particles in the various cellular nanomatrices described herein. These powder compacts400may also be configured to provide substantially enhanced properties as compared to powder compacts formed from pure Mg particles that do not include the nanoscale coatings described herein. Powder compacts400that include dispersed particles414comprising Mg and nanomatrix416comprising various nanomatrix materials420described herein have demonstrated room temperature compressive strengths of at least about 37 ksi, and have further demonstrated room temperature compressive strengths in excess of about 50 ksi, both dry and immersed in a solution of 3% KCl at 200° F. In contrast, powder compacts formed from pure Mg powders have a compressive strength of about 20 ksi or less. Strength of the nanomatrix powder metal compact400can be further improved by optimizing powder210, particularly the weight percentage of the nanoscale metallic coating layers216that are used to form cellular nanomatrix416. Strength of the nanomatrix powder metal compact400can be further improved by optimizing powder210, particularly the weight percentage of the nanoscale metallic coating layers216that are used to form cellular nanomatrix416. For example, varying the weight percentage (wt. %), i.e., thickness, of an alumina coating within a cellular nanomatrix16formed from coated powder particles212that include a multilayer (Al/Al2O3/Al) metallic coating layer216on pure Mg particle cores214provides an increase of 21% as compared to that of 0 wt % alumina.

Powder compacts400comprising dispersed particles414that include Mg and nanomatrix416that includes various nanomatrix materials as described herein have also demonstrated a room temperature sheer strength of at least about 20 ksi. This is in contrast with powder compacts formed from pure Mg powders, which have room temperature sheer strengths of about 8 ksi.

Powder compacts400of the types disclosed herein are able to achieve an actual density that is substantially equal to the predetermined theoretical density of a compact material based on the composition of powder210, including relative amounts of constituents of particle cores214and metallic coating layer216, and are also described herein as being fully-dense powder compacts. Powder compacts400comprising dispersed particles that include Mg and nanomatrix416that includes various nanomatrix materials as described herein have demonstrated actual densities of about 1.738 g/cm3to about 2.50 g/cm3, which are substantially equal to the predetermined theoretical densities, differing by at most 4% from the predetermined theoretical densities.

Powder compacts400as disclosed herein may be configured to be selectively and controllably dissolvable in a wellbore fluid in response to a changed condition in a wellbore. Examples of the changed condition that may be exploited to provide selectable and controllable dissolvability include a change in temperature, change in pressure, change in flow rate, change in pH or change in chemical composition of the wellbore fluid, or a combination thereof. An example of a changed condition comprising a change in temperature includes a change in well bore fluid temperature. For example, powder compacts400comprising dispersed particles414that include Mg and cellular nanomatrix416that includes various nanomatrix materials as described herein have relatively low rates of corrosion in a 3% KCl solution at room temperature that range from about 0 to about 11 mg/cm2/hr as compared to relatively high rates of corrosion at 200° F. that range from about 1 to about 246 mg/cm2/hr depending on different nanoscale coating layers216. An example of a changed condition comprising a change in chemical composition includes a change in a chloride ion concentration or pH value, or both, of the wellbore fluid. For example, powder compacts400comprising dispersed particles414that include Mg and nanomatrix416that includes various nanoscale coatings described herein demonstrate corrosion rates in 15% HCl that range from about 4750 mg/cm2/hr to about 7432 mg/cm2/hr. Thus, selectable and controllable dissolvability in response to a changed condition in the wellbore, namely the change in the wellbore fluid chemical composition from KCl to HCl, may be used to achieve a characteristic response as illustrated graphically inFIG. 11, which illustrates that at a selected predetermined critical service time (CST) a changed condition may be imposed upon powder compact400as it is applied in a given application, such as a wellbore environment, that causes a controllable change in a property of powder compact400in response to a changed condition in the environment in which it is applied. For example, at a predetermined CST changing a wellbore fluid that is in contact with powder contact400from a first fluid (e.g. KCl) that provides a first corrosion rate and an associated weight loss or strength as a function of time to a second wellbore fluid (e.g., HCl) that provides a second corrosion rate and associated weight loss and strength as a function of time, wherein the corrosion rate associated with the first fluid is much less than the corrosion rate associated with the second fluid. This characteristic response to a change in wellbore fluid conditions may be used, for example, to associate the critical service time with a dimension loss limit or a minimum strength needed for a particular application, such that when a wellbore tool or component formed from powder compact400as disclosed herein is no longer needed in service in the wellbore (e.g., the CST) the condition in the wellbore (e.g., the chloride ion concentration of the wellbore fluid) may be changed to cause the rapid dissolution of powder compact400and its removal from the wellbore. In the example described above, powder compact400is selectably dissolvable at a rate that ranges from about 0 to about 7000 mg/cm2/hr. This range of response provides, for example the ability to remove a 3 inch diameter ball formed from this material from a wellbore by altering the wellbore fluid in less than one hour. The selectable and controllable dissolvability behavior described above, coupled with the excellent strength and low density properties described herein, define a new engineered dispersed particle-nanomatrix material that is configured for contact with a fluid and configured to provide a selectable and controllable transition from one of a first strength condition to a second strength condition that is lower than a functional strength threshold, or a first weight loss amount to a second weight loss amount that is greater than a weight loss limit, as a function of time in contact with the fluid. The dispersed particle-nanomatrix composite is characteristic of the powder compacts400described herein and includes a cellular nanomatrix416of nanomatrix material420, a plurality of dispersed particles414including particle core material418that is dispersed within the matrix. Nanomatrix416is characterized by a solid-state bond layer419, which extends throughout the nanomatrix. The time in contact with the fluid described above may include the CST as described above. The CST may include a predetermined time that is desired or required to dissolve a predetermined portion of the powder compact200that is in contact with the fluid. The CST may also include a time corresponding to a change in the property of the engineered material or the fluid, or a combination thereof. In the case of a change of property of the engineered material, the change may include a change of a temperature of the engineered material. In the case where there is a change in the property of the fluid, the change may include the change in a fluid temperature, pressure, flow rate, chemical composition or pH or a combination thereof. Both the engineered material and the change in the property of the engineered material or the fluid, or a combination thereof, may be tailored to provide the desired CST response characteristic, including the rate of change of the particular property (e.g., weight loss, loss of strength) both prior to the CST (e.g., Stage1) and after the CST (e.g., Stage2), as illustrated inFIG. 11.

Without being limited by theory, powder compacts400are formed from coated powder particles212that include a particle core214and associated core material218as well as a metallic coating layer216and an associated metallic coating material220to form a substantially-continuous, three-dimensional, cellular nanomatrix416that includes a nanomatrix material420formed by sintering and the associated diffusion bonding of the respective coating layers216that includes a plurality of dispersed particles414of the particle core materials418. This unique structure may include metastable combinations of materials that would be very difficult or impossible to form by solidification from a melt having the same relative amounts of the constituent materials. The coating layers and associated coating materials may be selected to provide selectable and controllable dissolution in a predetermined fluid environment, such as a wellbore environment, where the predetermined fluid may be a commonly used wellbore fluid that is either injected into the wellbore or extracted from the wellbore. As will be further understood from the description herein, controlled dissolution of the nanomatrix exposes the dispersed particles of the core materials. The particle core materials may also be selected to also provide selectable and controllable dissolution in the wellbore fluid. Alternately, they may also be selected to provide a particular mechanical property, such as compressive strength or sheer strength, to the powder compact400, without necessarily providing selectable and controlled dissolution of the core materials themselves, since selectable and controlled dissolution of the nanomatrix material surrounding these particles will necessarily release them so that they are carried away by the wellbore fluid. The microstructural morphology of the substantially-continuous, cellular nanomatrix416, which may be selected to provide a strengthening phase material, with dispersed particles414, which may be selected to provide equiaxed dispersed particles414, provides these powder compacts with enhanced mechanical properties, including compressive strength and sheer strength, since the resulting morphology of the nanomatrix/dispersed particles can be manipulated to provide strengthening through the processes that are akin to traditional strengthening mechanisms, such as grain size reduction, solution hardening through the use of impurity atoms, precipitation or age hardening and strength/work hardening mechanisms. The nanomatrix/dispersed particle structure tends to limit dislocation movement by virtue of the numerous particle nanomatrix interfaces, as well as interfaces between discrete layers within the nanomatrix material as described herein. This is exemplified in the fracture behavior of these materials. A powder compact400made using uncoated pure Mg powder and subjected to a shear stress sufficient to induce failure demonstrated intergranular fracture. In contrast, a powder compact400made using powder particles212having pure Mg powder particle cores214to form dispersed particles414and metallic coating layers216that includes Al to form nanomatrix416and subjected to a shear stress sufficient to induce failure demonstrated transgranular fracture and a substantially higher fracture stress as described herein. Because these materials have high-strength characteristics, the core material and coating material may be selected to utilize low density materials or other low density materials, such as low-density metals, ceramics, glasses or carbon, that otherwise would not provide the necessary strength characteristics for use in the desired applications, including wellbore tools and components.