METHODS OF USE OF EXPANDABLE GROUT FOR IMPROVED ZONAL ISOLATION

Description

FIELD OF THE DISCLOSURE

The present disclosure relates to systems and methods for grout expansion with hydraulic fracturing environments.

BACKGROUND

Numerous factors can affect the effectiveness of the drilling and completions of—and subsequent intervention operations in—both producer and injector wells. Many of these operations depend on the ability to isolate portions of the downhole environment either during the phases of well execution, production, or injection. Lack of isolation can lead to a number of challenges.

During drilling and cementing of various well types, thief zones (which could include zones with significant vugs/fracs/faults) are periodically encountered that can cause significant losses of the injected drilling fluids/muds, cement, completion, stimulation, and intervention fluids. These losses can cause both operational issues (such as requirements for excess volumes of mud/cement) as well as well-control issues during the drilling of these wells.

Currently, loss control pills are deployed during these operations to plug the fracs/vugs/permeability that contribute to significant losses. However, these solutions are often either ineffective or slow to provide appropriate bridging and fluid loss control.

Similarly, drilling operations in many formations may identify streaks or zones of shales with high water sensitivity. The water-sensitivity (to fluids such as the water phase in drilling fluids, completions fluids, fracturing fluids, stimulation fluids, or produced water) could lead to disaggregation of the shale streak into finer, mobile particles. This could cause either collapse of the open hole or washout (during drilling); premature screenouts (during completions such as gravel pack); or it could lead to sand production or fines migration damage (if experienced during production). In principle, the filtercake formed on the formation borehole from drilling fluid leakoff should prevent significant leakoff and exposure to aqueous fluids that might trigger these consequences of water-sensitivity.

Production wells will often experience deleterious production from isolated streaks, zones, perforations, or induced (hydraulic) fractures. This could include production of significant contributions of water or gas, such as a producer well experiencing water coning (where water preferentially enters the lowermost intervals and perforations).

Numerous methods are known for shut-off and isolation of intervals which have experienced losses, high sanding potential, or deleterious production of water or gas. Chemical solutions for zonal shut-off are available and include gels (specifically crosslinked polymers) or micro-cements that can be injected into a formation or a fracture and allowed to cure and prevent flow. However, these current chemical systems have several disadvantages: some of the systems do not have a mechanism for chemical bonding to the formation, which can lead to debonding and extrusion of these systems from the formation and ultimate failure. Additionally, these systems are intended to be low-viscosity during injection, to increase penetration and minimize risk of exceeding the frac gradient; but some systems undergo premature gelation to form higher viscosities and do not achieve the desired penetration into the formation matrix.

Mechanical solutions to isolate these zones include either bridge-plugs, mechanical patches, or blank pipe set across intervals. These systems have several disadvantages as well. For example, in completions with mechanical obstructions (casing deformation, fish in hole, others), mechanical isolation systems can often not pass through to seal/isolate at the desired depth. These systems are often prone to different modes of mechanical failure or other loss of pressure resistance. They also are often placed at inaccurate depth if their placement was not supported with sufficient preliminary data.

In injector wells, similar high-permeability or vug-laden (thief) zones can also promote localized influx and losses of injected fluids, leaving large portions of the pay zone without injection. This nonuniform injection profile can cause issues in sweep efficiency through the reservoir; this can often expedite water or gas breakthrough and/or other losses in producer wells that experience pressure support benefit from the injector.

Isolation of these thief zones in injector well completions has been similarly accomplished using chemical and mechanical means. Multiple performance-deficiencies exist in these current methods. Therefore, there is a need to provide an invention that overcome these deficiencies.

SUMMARY OF THE DISCLOSURE

In some aspects, the techniques described herein relate to a method for zonal isolation and protection of sensitive lithologies in a wellbore, including: injecting a precursor mixture into the porous matrix or hydraulic fracture within a target interval; allowing the mixture to expand and bond within the target interval to form an expanded volume; introducing a displacement fluid to the target interval; and shutting in the wellbore to enable the mixture to harden, thereby creating a rigid, low-permeability porous plug that isolates the target interval. In optional embodiments, any subsequent drilling operations may resume through the hardened grout material, wherein the protective barrier is maintained across one or more sensitive lithologies.

In some aspects, the techniques described herein relate to a method for zonal isolation and reinforcement of hydraulic fractures and perforations in a wellbore, including: introducing a mixture of an isocyanate precursor and a polyol precursor into one or more hydraulic fractures or perforations or faults in proximity of a wellbore; allowing the mixture to chemically bond to the walls of the fractures or perforation or fault, followed by expansion within the fractures/perforations/faults to form an expanded material configured to provide zonal isolation and reinforcement; injecting the mixture under conditions and in volumes sufficient to achieve a desired level of isolation and reinforcement; introducing the mixture into perforations and adjacent formation matrix in cased hole completions to create a wellbore plug for zonal isolation; utilizing the chemically bonded and expanded mixture to create a barrier with significant resistance to injection into and production from the treated fractures or perforations; employing the method in wellbores of any inclination.

Further features of the disclosed systems and methods, and the advantages offered thereby, are explained in greater detail hereinafter with reference to specific example embodiments illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate a fuller understanding of the present invention, reference is now made to the attached drawings. The drawings should not be construed as limiting the present invention but are intended only to illustrate different aspects and embodiments of the invention.

FIG. 1A illustrates hydraulic fractures being filled with a hardening mixture.

FIG. 1B illustrates hydraulic fractures being filled with a hardening mixture.

FIG. 2A illustrates treating an upper stage of a multi-stage hydraulic fractured completion with expandable grout.

FIG. 2B illustrates treating an upper stage of a multi-stage hydraulic fractured completion with expandable grout.

FIG. 2C illustrates treating an upper stage of a multi-stage hydraulic fractured completion with expandable grout.

DETAILED DESCRIPTION

Exemplary embodiments of the invention will now be described in order to illustrate various features of the invention. The embodiments described herein are not intended to be limiting as to the scope of the invention, but rather are intended to provide examples of the components, use, and operation of the invention.

Furthermore, the described features, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific features, advantages, and characteristics of an embodiment. In other instances, additional features, advantages, and characteristics may be recognized in certain embodiments that may not be present in all embodiments. One skilled in the relevant art will recognize that the features, advantages, and characteristics of any embodiment can be interchangeably combined with the features, advantages, and characteristics of any other embodiment.

The diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present invention.

Expandable grout solutions have been recently matured (and disclosed) for use in subterranean applications for Plug and Abandonment. These systems, which generally comprise expandable polyurethane systems, possess numerous chemical and physical features which could add value in a wider range of applications. Specifically, two-component polyurethane grout materials undergo a volume expansion that may range from 2 to 20-fold the original volume of the liquid precursors. The expanded grout then undergoes a hardening polymerization, that often yields a closed-cell structure with low permeability. The grouts are also known to physically and/or chemically bond to formation mineralogies, cement, and metal casing or tubing, leading to high shear bond strength. The physical properties (expansion-%, permeability, shear bond) of the hardened resin can vary depending on the specific chemistry of the grout precursors, which includes the presence and chemical identity of physical or chemical blowing agents in the blended grout.

The Grout Composition

The current invention proposes injecting a mixture of the blended polyurethane precursors into a formation matrix; a hydraulic fracture; or perforations, most preferably at a rate sufficiently low to avoid exceeding the fracturing pressure of the formation. Due to the higher viscosity of the many polyurethane grouts (before full expansion), the designed depth of penetration may be quite shallow (such as <6″ radially). However, alternative embodiments could include injecting a lower-viscosity blend of polyurethane precursors, to achieve deeper penetration into the formation. Deeper penetration will lead to higher resistance against failure and subsequent deleterious production from or injection into those zones, leading to possibly higher short- and long-term effectiveness. In the preferred embodiment, the injected polyurethane would build a strong chemical bond to the formation grains after expansion in the pore space. The preferred polyurethane would also form a low-permeability (possibly closed-cell) expanded material, which would have significant resistance to injection or production.

In the current invention, the preferred precursors would comprise precursors of polyurethane into an optimized blend in a mass ratio of roughly 50:50 (+/−10%) to yield high quality, porous, and impermeable solid grouts. These precursors would each preferably exhibit low viscosities, preferably <500 cP, more preferably <200 cP, more preferably <100 cP.

In some embodiments, the expansion behavior under downhole conditions is well known in advance. This includes both the degree of expansion (in exposure to downhole fluids) as well as the viscosity increase, %-expansion of volume, and temperature exotherm as a function of time. These parameters are critical for the safe design and execution of an expandable polyurethane grout for zonal isolation applications.

Additionally, the expansion of polyurethane grouts is achieved through the inclusion of either chemical or physical blowing agents. Chemical blowing agents undergo some reaction with one of the precursors or nearby chemical constituents and generates significant gas to achieve expansion of the precursor blend; physical blowing agents undergo release from soluble/liquid form and undergo gaseous expansion without chemically reacting with the precursors. Preferred embodiments could use either physical or chemical blowing agent (depending on the ultimate properties of the composite).

Generally, FIGS. 1A-1B and 2A-2C uses of liquid polyurethane (grout) precursor blends which, when pumped into target intervals, will expand and bond to isolate those zones. The intended application will include either isolation of production of liquid or gas from those treated intervals or injection of water or gas into the target interval. While multiple methods of deployment will be detailed below, the preferred method of deployment will involve injection of a mixture of an isocyanate and a polyol precursor into either the formation matrix or a fracture (individual or network) within a target interval. This injection will be followed by an optional displacement fluid as well as an optional shut-in to allow the polyurethane to harden into a rigid, low-permeability porous plug before subsequent operations. This treatment may comprise injection fully into the formation/fracture past the wellbore or may comprise an additional optional wellbore plug as an additional barrier across the zone of interest. The preferred embodiments will design an expanded volume of polyurethane that will preferentially seal across only those intervals desired to be isolated without any sealing across zones within which sealing is not desired.

For cases of zonal isolation, an expandable, low-permeability grout as described here could add unique advantages over current systems deployed for zonal isolation. These advantages are specifically noteworthy compared to current chemical methods for zonal isolation. First, the depth of penetration of the (unexpanded or partially expanded) grout into a fracture or formation porosity will likely be higher versus microcements used for zonal isolation. The outward expansion of the polyurethane bubbles (and subsequent hardening) will also likely provide a more robust barrier against production/injection through the treated zone, versus static systems that do not expand. Finally, the enhanced chemical bonding of polyurethane grout to formation grains can yield improved resistance against debonding-related failure.

In a related alternative method, the injection of the blended polyurethane is intended to coat and isolate sensitive lithologies and minerals exposed during drilling and completion operations. An example embodiment could involve injecting a pill of expandable grout across sensitive shale streak during the drilling process, to seal it and prevent wellbore collapse. An optional embodiment could include spotting a pill of expandable grout across a sensitive shale streak exposed in the open hole (during drilling); stopping drilling long enough for the polyurethane to expand and harden; then commencing drilling again through the hardened grout plug (leaving the protecting layer of polymer intact across the shale streak exposed in the open hole). The expandable grout would show particular advantage when spotted across a shale interval exposed in the open hole section that had experienced washout during drilling, expanding within that void and sealing against the formation face and exposed shale. This method could optionally be achieved through partial penetration into the matrix; but due to the low permeability of shale intervals, matrix penetration is less likely and the sealing action to isolate the shales may occur preferentially through a chemical bonding to (and expansion against) these sensitive lithologies.

For any such treatment for zonal isolation, the preferred candidate well would have sufficient data to justify the specific intervals (depths) or fractures to be isolated through this treatment. This could include multiphase Production Log (PLT) data (showing the zones with highest influx of liquids or gas); Injection Logs (ILT), allowing identification of those zones in which it was desired to reduce injection; and other logs such as spectral Gamma Ray, which can be used to identify shale streaks that require isolation. For embodiments to achieve zonal isolation of production, the most preferred candidate conditions would also have permeability conditions which would limit crossflow behind any polyurethane grout barrier injected for zonal isolation; This includes a candidate well with high permeability-anisotropy (or low kv/kh in vertical well completions).

FIG. 1A illustrates an isolated view of a hydraulic fracturing system 100 including a wellbore 105 and one or more individual hydraulic fractures 110. The fractures 110 to be treated could be of irregular geometry or be of traditional biwing geometry.

The wellbore 105 could be an open hole wellbore or cased wellbore. There is some improved ability to isolate injection of the grout precursor blend into cased hole zones when using mechanical packers. By comparison, isolation of injection is often challenged in open hole formations; however localized placement of expandable grout near to the target interval could be aided by the volume-expansion of the grout into a hydraulic fracture even without use of packers to further encourage directed placement.

The fractures 110 may be previously installed in either vertical or horizontal wellbores prior to the desired isolation. There may be heightened complexity to isolate treatment of specific fracs in multistage fracture completions in horizontal wellbores. Much of this challenge comes from difficulty deploying through-tubing mechanical isolation in extended horizontal wellbores. The preferred candidate would have multiple existing fractures 110 that are not in communication with each other.

The injected blend of polyurethane precursors 125 would build a strong chemical bond to the walls of the fracture 110 and optionally proppant grains after expansion 130 within the fracture 110. The preferred polyurethane would also form a low permeability (possibly closed-cell) expanded material, which would have significant resistance to injection into or production from the polyurethane-filled fracture.

Note that similar embodiments can involve isolation of perforations in cased hole completions through injection of expandable polyurethane grout. The intended application could include injection into perforations to only place grout within the perforations themselves. Alternative embodiments could include injection of the blended grout into the perforations and an adjacent formation matrix, such as in a completion lacking hydraulic fractures. Further optional embodiments could include injection of the blended grout into the perforations but also leaving additional polyurethane within the casing to provide additional isolation of the target interval through a wellbore plug.

One enabling aspect of these embodiments is the ability to predict the volume of the desired perforations and to design the treatment volume and/or the expected expanded volume of grout to pack them with plugging grout to the appropriate volume level. The pack may be with or without applied pressure.

In the preferred embodiment, the injected polyurethane would build a strong chemical bond to the perforation walls following expansion within the fractures. The preferred polyurethane would also form a low-permeability (possibly closed-cell) expanded material, which would have significant resistance to injection or production.

For natural fractures, vugs, and fissures, the preferable downhole conditions would include an initial understanding or estimate of the overall porosity of the interval that will be treated. This information will be useful to properly design an appropriate volume of grout to inject to properly isolate that interval. Preferred conditions would also include the location and orientation of any macroscopic faults. The preferred candidate would also have sufficient matrix permeability surrounding the fractures to enable leakoff of the fluids or gas that fill the fractures and vugs prior to grout injection.

FIG. 2A is a method diagram illustrating a fractured hydraulic wellbore 200 according to the method of injection grout into a hydraulic fracture. The wellbore can include generally a reservoir 205 which surrounds a layer of cementing 210 which itself surrounds a casing 215. Within a smaller radius of the casing 215 there can be a screen assembly 220 which can run continuously or intermittently down the wellbore. For example, the screen assemblies 220 can be positioned at or near a first fracture 225 and second fracture 230. Produced materials 235 from the fractures 225 and 230 can flow out of the screen assemblies 220 and toward the surface through the wellbore.

FIG. 2B illustrates how, after the produced materials 235 flow out up with wellbore, blended grout precursors can be injected through the screen assemblies 220 adjacent to the desired fracture or fractures according to one or more of the processes described herein. The blended grout precursors 240 can be made or composed according to one or more of the embodiments described above.

Consistent with any technique for zonal isolation using chemical solutions, it is imperative to place the injected materials into or adjacent to only those zones desired to isolate and NOT additional zones. Improper placement of isolating materials, including expandable polyurethanes, can impair the productivity and injectivity of otherwise productive zones. As such, some embodiments may implement a number of methods of mechanical or chemical placement into targeted intervals (desired for isolation by the injected polyurethane grout). In some optional embodiments, isolation of grout precursor blend injection can happen by the placement of a removable bridge plug or cement retainer below some perforations into which the injection of polyurethane can be placed. Optional embodiments may further comprise isolated injection of the grout between packer and bridge plug placed across the target interval. Further optional embodiments may include use of coiled tubing with inflatable packers to focus injection of the polyurethane blend into a target zone between the inflatable packers.

Other variables that will impact the method of placement center around the means of deploying the separate precursors downhole. In certain embodiments of the current injection, the isocyanate and the polyol and/or resin precursors will be deployed separately downhole (to avoid rapid reactivity) where they are thoroughly mechanically mixed downhole. These optional embodiments of “dual-conveyance” could include a number of different methods to deploy parallel streams of precursor toward a downhole mixer. These methods could include hoses or coils banded or attached to a drill-string downhole; hoses in a concentric coil-tubing string; or other similar methods of parallel dual-conveyance of precursors to a downhole mixing chamber. The mixing chamber could be assembled such that it is placed adjacent to or slightly above the zone of interest; and they could be designed to reside above or between packers in cases of isolated injection.

Depending on the intended use of the grout and the candidate zone requiring isolation, the designed volume and method of application may vary according to the following conditions:

Zonal isolation across specific interval within the wellbore (low to medium penetration): In this embodiment, a mixture of expandable grout precursors is injected downhole, blended and placed across a target zone. In the preferred embodiments, the estimated volume of precursors will be just sufficient to place the desired volume of polyurethane AFTER expansion across the target interval. The volume of blended precursors will, then, be calculated as the desired wellbore volume (across the target interval, plus any safety factor), divided by the expansion factor for the expandable grout under downhole conditions.

Partial squeeze into perforations: In this embodiment, the expandable polyurethane blend is injected into and intended to seal within a series of perforations. To calculate the desired volume to inject, the volume of the perforations in the target or isolated intended zone is first calculated in the number of perforations (shots per foot multiplied by the target interval) multiplied by the estimated volume for each perforation (which will be a rough estimate based on possible irregular volume of perforation) multiplied by the percentage of perfs estimated to open to injection. This total volume is then divided by the expansion factor for the expandable grout formulation under downhole conditions and will then possibly be added with a safety factor volume to account for possible volume losses in transit downhole.

In optional embodiments, the polyurethane precursor blend will be injected through the perforations for some partial penetration and displaced so there is just sufficient polyurethane precursor in the perforations to expand within and fill the perforation. This volume may be slightly larger (allowing partial matrix penetration) than perf-filling volume alone.

Squeeze into formation matrix (penetration taking care not to exceed frac gradient): In this embodiment, the expandable polyurethane blend is injected into the porous formation matrix itself. To calculate the desired volume to inject into the matrix, an estimated volume of the matrix is calculated using the formation porosity multiplied by the height of the desired interval and also considering the intended radial depth of penetration into the formation. This total volume of polyurethane precursor liquid is then optionally divided by the expansion factor for the polyurethane grout formulation under downhole conditions. The expansion-corrected volume may then add an additional safety factor (%-volume) to account for possible volume losses in transit downhole.

Squeeze into natural or hydraulic fractures: In this embodiment, the expandable polyurethane blend is injected into and intended to seal within the walls of fractures downhole.

FIG. 2C illustrates the hydraulic fractures after the grout from 240 has cured. After some time, the grout 240 can cure and expand in 245. With one or more fractures effectively contained by the expanded and cured grout, an isolated production 250 can flow through the screen assembly 220 and up the wellbore.

The current invention proposes injecting a mixture of the blended polyurethane precursors into the formation matrix, most preferably at a rate sufficiently low to avoid exceeding the fracturing pressure of the formation. Due to the moderate to high viscosity of the many polyurethane grouts (before full expansion), the designed depth of penetration may be quite shallow (such as <6″ radially). However, alternative embodiments could include injecting a lower-viscosity blend of polyurethane precursors, to achieve deeper penetration into the formation. Deeper penetration will lead to higher resistance against failure and subsequent deleterious production from or injection into those zones, leading to possibly higher short- and long-term effectiveness. In the preferred embodiment, the injected polyurethane would build a strong chemical bond to the formation grains after expansion in the pore space. The preferred polyurethane would also form a low-permeability (possibly closed-cell) expanded material, which would have significant resistance to injection or production.

In the current invention, the preferred precursors would comprise precursors of polyurethane that can readily be blended in a mass ratio of roughly 50:50 (+/−10%) to yield high quality, porous, and impermeable solid grouts. These precursors would each preferably exhibit low viscosities, preferably <500 cP, more preferably <200 cP, more preferably <100 cP.

In some embodiments, the expansion behavior under downhole conditions is well known in advance. This includes both the degree of expansion (in exposure to downhole fluids) as well as the viscosity increase, %-expansion of volume, and temperature exotherm as a function of time. These parameters are critical for the safe design and execution of a polyurethane for zonal isolation applications.

To calculate the desired volume to inject to a natural fracture, the volume of the natural fracture network must first be estimated within the zone height to be treated. With low likelihood to estimate the actual volume of these natural (irregular shaped) frac networks, an estimate of volume may be made based on an expected porosity of the fractured formation. (Ultimately the injected volume is only expected to partially penetrate these natural fractures in the near wellbore region; so, depth of penetration of the pre-expanded polyurethane blend may be useful to estimate the frac volume to be treated.) This total volume is then divided by the expansion factor for the expandable grout formulation under downhole conditions and will then possibly be added with a safety factor volume to account for possible volume losses in transit downhole.

To calculate the desired volume to inject into hydraulic fractures, the volume of the propped fracture(s) must first be estimated within the zone height to be treated. In the preferred embodiments, the frac geometry will be estimated based on the injected volume of the proppant (into the specific frac of interest) multiplied by the porosity of the packed propping agent. And again, the injected volume may be designed to partially-penetrate the hydraulic frac most preferably in the near wellbore region; so, the desired volume of frac to treat may be corrected for the expected depth of penetration of the pre-expanded polyurethane blend into the fracture. This total treatment-volume is then divided by the expansion factor for the expandable grout formulation under downhole conditions and will then possibly be corrected upward with a safety factor volume to account for possible volume losses in transit downhole.

The total volume of polyurethane precursor blend to design for in each of these embodiments already accounts for the additional expansion volume as well as the potential volume losses during transit downhole. In an optional embodiment, any of the above volume-based embodiments may be adjusted further to include an underdisplacement, such that a wellbore plug may be formed in addition to the penetrative volume of polyurethane intended to inject into the formation, perforations, or fractures. In this embodiment, an additional volume of polyurethane will be added to fill the wellbore across the target interval; however, access through the wellbore in this embodiment would require milling through the resultant wellbore plug following curing of the polyurethane plug.

In some aspects, the techniques described herein relate to a method for zonal isolation and protection of sensitive lithologies close to a wellbore, including: injecting a precursor mixture into the wellbore to a target depth; allowing the mixture to expand and bond within the wellbore at target interval to form an expanded volume; introducing a flush fluid to displace the polyurethane precursor blend only to the target depth; shutting in the wellbore to enable the mixture to harden, thereby creating a rigid, low-permeability and/or impermeable porous plug that isolates the target interval; and continuing drilling operations through the hardened polyurethane plug, wherein the protective barrier is maintained across one or more sensitive lithologies.

In some aspects, the techniques described herein relate to a method, wherein the polyurethane precursors are injected into the formation matrix at a rate sufficiently low to avoid exceeding the fracturing pressure of the formation.

In some aspects, the techniques described herein relate to a method, wherein the mixture includes an isocyanate precursor and a polyol precursor.

In some aspects, the techniques described herein relate to a method, wherein volume includes polyurethane.

In some aspects, the techniques described herein relate to a method, wherein the volume preferentially seals across only one or more predetermined lithologies, e.g., a rock formation having a particular set of characteristics.

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In some aspects, the techniques described herein relate to a method for zonal isolation and reinforcement of hydraulic fractures and perforations in a wellbore, including: introducing a mixture of an isocyanate precursor and a polyol precursor into one or more hydraulic fractures within a wellbore; allowing the mixture to chemically bond to the walls of the fractures, followed by expansion within the fractures to form an expanded material configured to provide zonal isolation and reinforcement; injecting the mixture under conditions and in volumes sufficient to achieve a desired level of isolation and reinforcement; introducing the mixture into perforations and adjacent formation matrix in cased hole completions to create a wellbore plug for zonal isolation; utilizing the chemically bonded and expanded mixture to create a barrier with significant resistance to injection into and production from the treated fractures or perforations; employing the method in wellbores of any inclination.

Additionally, the expansion of polyurethane grouts is achieved through the inclusion of either chemical or physical blowing agents. Chemical blowing agents undergo some reaction with one of the precursors and generates significant gas to achieve expansion of the blend; physical blowing agents undergo release from soluble/liquid form and undergo gaseous expansion without reacting with the precursors. Preferred embodiments could use either physical or chemical blowing agent (depending on the ultimate properties of the composite).

Although embodiments of the present invention have been described herein in the context of a particular implementation in a particular environment for a particular purpose, those skilled in the art will recognize that its usefulness is not limited thereto and that the embodiments of the present invention can be beneficially implemented in other related environments for similar purposes. The invention should therefore not be limited by the above-described embodiments, method, and examples, but by all embodiments within the scope and spirit of the invention as claimed.

Further, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The terms “a” or “an” as used herein, are defined as one or more than one. The term “plurality” as used herein, is defined as two or more than two. The term “another” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e., open language). Also, for purposes of description herein, the terms “upper,” “lower,” “left,” “rear,” “right,” “front,” “vertical,” “horizontal,” and derivatives thereof relate to the invention as oriented in the figures and is not to be construed as limiting any feature to be a particular orientation, as said orientation may be changed based on the user's perspective of the device.

In the invention, various embodiments have been described with references to the accompanying drawings. It may, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The invention and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.

The invention is not to be limited in terms of the particular embodiments described herein, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope. Functionally equivalent systems, processes and apparatuses within the scope of the invention, in addition to those enumerated herein, may be apparent from the representative descriptions herein. Such modifications and variations are intended to fall within the scope of the appended claims. The invention is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such representative claims are entitled.

The preceding description of exemplary embodiments provides non-limiting representative examples referencing numerals to particularly describe features and teachings of different aspects of the invention. The embodiments described should be recognized as capable of implementation separately, or in combination, with other embodiments from the description of the embodiments. A person of ordinary skill in the art reviewing the description of embodiments should be able to learn and understand the different described aspects of the invention. The description of embodiments should facilitate understanding of the invention to such an extent that other implementations, not specifically covered but within the knowledge of a person of skill in the art having read the description of embodiments, would be understood to be consistent with an application of the invention.