EXPANDABLE POLYMER GROUT FOR WELLBORE APPLICATIONS

Abstract

An expandable polymer grout system comprises an isocyanate component and an organic polyol component that when combined form a grout for bonding to equipment used in a wellbore. In a first instance, the grout is used with a retrieval system to bond to an obstruction in a wellbore for retrieving the obstruction from the wellbore. In a second instance, the grout is used with a deployment system to secure a sensor to downhole equipment within a wellbore. In a third instance, the grout is used to secure a casing centralizer to an outer surface of a casing before the casing is placed in a wellbore. In a fourth instance, the grout is molded to form a casing centralizer on an outer surface of a casing before the casing is placed in a wellbore.

Claims

1. A method of retrieving an obstruction from a wellbore, the method comprising: deploying a retrieval system in the wellbore, the retrieval system comprising a retrieval tool; combining, with the retrieval system, components of an expandable polymer grout system to form a grout; engaging the obstruction with the retrieval tool and the grout; and retracting the obstruction with the retrieval system from the wellbore.

2. The method of claim 1, wherein the retrieval tool is one of a spear, a hook, an overshot tool, or a grasping tool.

3. The method of claim 1, wherein the retrieval system comprises a cannister system that mixes the components of the expandable polymer grout system within the wellbore to form the grout.

4. The method of claim 3, wherein the cannister system comprises an isocyanate cannister, an organic polyol cannister, and a mixer.

5. The method of claim 4, wherein the cannister system further comprises a lubricant cannister comprising a lubricant.

6. The method of claim 1, wherein the retrieval system comprises a conduit system for delivering the components of the expandable polymer grout system from a surface of the wellbore to a target location.

7. The method of claim 6, wherein the retrieval system further comprises a mixer that receives the components of the expandable polymer grout system from the conduit system and mixes the components of the expandable polymer grout system.

8. A method of attaching a sensor to downhole equipment in a wellbore, the method comprising: identifying a target location within the wellbore for the sensor; providing, with a deployment system, an expandable polymer grout system to the target location within the wellbore; combining, with the deployment system, components of the expandable polymer grout system within the wellbore to form a grout; delivering the grout to the target location within the wellbore; and allowing the grout to cure thereby securing the sensor to the downhole equipment within the wellbore.

9. The method of claim 8, wherein the deployment system comprises a tailpipe that delivers the grout to the sensor and the downhole equipment.

10. The method of claim 8, wherein the deployment system comprises a conduit system for delivering the components of the expandable polymer grout system to the target location.

11. The method of claim 10, wherein the deployment system further comprises a mixer that receives the components of the expandable polymer grout system from the conduit system and mixes the components of the expandable polymer grout system.

12. The method of claim 8, wherein the deployment system comprises a cannister system that mixes the components of the expandable polymer grout system within the wellbore to form the grout.

13. The method of claim 12, wherein the cannister system comprises an isocyanate cannister, an organic polyol cannister, and a mixer.

14. A method of deploying a casing in a wellbore, the method comprising: placing a casing centralizer onto an outer surface of a casing: combining, with a deployment system, components of an expandable polymer grout system to form a grout; delivering the grout to a contact point at which the casing centralizer contacts the outer surface of the casing; allowing the grout to cure thereby securing the casing centralizer to the outer surface of the casing; and placing the casing with the casing centralizer into the wellbore.

15. The method of claim 14, wherein the deployment system comprises: a mixer that combines the components of the expandable polymer grout system to form the grout; and a conduit that delivers the grout to the contact point.

16. The method of claim 14, wherein the components of the expandable polymer grout system comprise an isocyanate component, an organic polyol component, and a blowing agent.

17. A method of deploying a casing in a wellbore, the method comprising: placing a centralizer mold onto an outer surface of a casing; combining, with a deployment system, components of an expandable polymer grout system to form a grout; delivering the grout to an annulus between the centralizer mold and the outer surface of the casing; allowing the grout to cure thereby forming a casing centralizer on the outer surface of the casing; after curing the grout, removing the centralizer mold from the outer surface of the casing; and placing the casing with the casing centralizer into the wellbore.

18. The method of claim 17, wherein the deployment system comprises: a mixer that combines the components of the expandable polymer grout system to form the grout; and a conduit that delivers the grout to the contact point.

19. The method of claim 17, wherein the components of the expandable polymer grout system comprise an isocyanate component, an organic polyol component, and a blowing agent.

20. The method of claim 19, wherein the components of the expandable polymer grout system further comprise a lubricant to increase a lubricity of the casing centralizer thereby facilitating placement of the casing into the wellbore.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0009] FIG. 1 is a sectional view drawing of a well system illustrating a method of using a grout with a retrieval system to retrieve an obstruction from a well in accordance with the example embodiments described herein.

[0010] FIG. 2 is a sectional view drawing of a well system illustrating a method of using a grout to attach a sensor to downhole equipment in a well in accordance with the example embodiments described herein.

[0011] FIG. 3 is a sectional view drawing of a well system illustrating a method of securing a casing centralizer to a casing in accordance with the example embodiments described herein.

[0012] FIG. 4 is a sectional view drawing of a well system illustrating a method of molding a casing centralizer onto a casing in accordance with the example embodiments described herein.

DEFINITIONS

[0013] To define more clearly the terms used herein, the following definitions are provided. Unless otherwise indicated, the following definitions are applicable to this disclosure. If a term is used in this disclosure but is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology can be applied, as long as that definition does not conflict with any other disclosure or definition applied herein or render indefinite or non-enabled any claim to which that definition is applied. To the extent that any definition or usage provided by any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls.

[0014] While compositions and methods are described in terms of comprising various components or steps, the compositions and methods can also consist essentially of or consist of the various components or steps, unless stated otherwise.

[0015] The terms a, an, and the are intended to include plural alternatives, e.g., at least one. The terms including, with, and having, as used herein, are defined as comprising (i.e., open language), unless specified otherwise.

[0016] Various numerical ranges are disclosed herein. When Applicant discloses or claims a range of any type, Applicant's intent is to disclose or claim individually each possible number that such a range could reasonably encompass, including end points of the range as well as any sub-ranges and combinations of sub-ranges encompassed therein, unless otherwise specified. For example, all numerical end points of ranges disclosed herein are approximate, unless excluded by proviso.

[0017] Values or ranges may be expressed herein as about, from about one particular value, and/or to about another particular value. When such values or ranges are expressed, other embodiments disclosed include the specific value recited, from the one particular value, and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent about, it will be understood that the particular value forms another embodiment. It will be further understood that there are a number of values disclosed therein, and that each value is also herein disclosed as about that particular value in addition to the value itself. In another aspect, use of the term about means 20% of the stated value, 15% of the stated value, 10% of the stated value, 5% of the stated value, 3% of the stated value, or 1% of the stated value.

[0018] The terms polymer seal and grout are used herein to refer to a polymer bond placed at a target location associated with a well system, the polymer bond being created by the expandable polymer grout systems described herein. The polymer seal or grout may be placed to bond to one or more materials or components associated with the well system. The components of the expandable polymer grout systems can be tailored to achieve one or more desired properties, such as an expansion rate, an expansion volume, a viscosity, a resilience, or a lubricity.

[0019] As referred to herein, the term wellbore includes the borehole in the formation and any tubulars and compositions positioned therein.

[0020] As referred to herein, the term coupled can refer to two components that are in direct contact or directly attached to one another as well as two components that are joined or attached by a third component.

DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0021] Expandable polymer grout systems and associated deployment methods are disclosed herein that are useful for bonding to one or more materials or components associated with a well system. The systems and methods described herein can be used in a variety of wells, including production wells and injection wells, which may be located onshore or offshore. The expandable polymer grout systems and methods described herein are particularly beneficial because of their adaptability to a variety applications encountered in often extreme environmental conditions associated with a well system.

[0022] The expandable polymer grout systems described herein can form a grout that can bond to both metallic and non-metallic materials. The components of the expandable polymer grout systems can be tailored to adjust the expansion rate and the expansion volume as the systems cure to form a grout. The expansion of the expandable polymer grout systems is advantageous in that the grout can fill uncertain or irregular geometries often encountered with well system components and materials. The components of the expandable polymer grout systems also can be tailored to adjust viscosity of the systems to control the manner in which they flow as they cure into a grout. Additionally, the components of the expandable polymer grout systems can be tailored to adjust the properties of the grout formed after curing, such properties including the strength, resilience, and lubricity of the grout. These and other advantages will be described further in connection with the example embodiments provided herein.

Expandable Polymer Grout System

[0023] As explained in greater detail below, the expandable polymer grout systems described herein can comprise an isocyanate component and an organic polyol component that react to form the expandable polymer grout. In certain embodiments, the expandable polymer grout systems are deployed with a blowing agent to a downhole location, for example, in a wellbore. The blowing agents can be physical or chemical blowing agents. Blowing agents can be, for example, inert liquids that have low boiling points and non-reactivity to isocyanate groups. These blowing agents are evaporated during exothermic reaction of polyurethane to generate blowing gas. In certain embodiments, the components of the expandable polymer grout system are in liquid or solution form (injectable during deployment) and will set up into an expanded state once adequately mixed together and placed at a target location along an interval in a wellbore.

[0024] The expandable polymer grout system according to the embodiments herein can be optimized in order to achieve various performance properties to ensure successful application through the example methods described herein. In particular, the systems and methods can be varied to optimize viscosity, permeability, density volume of expansion, expansion percentage, curing time and water sensitivity as the expandable polymer grout systems are curing. The system can be further varied to optimize the strength, resilience, and lubricity of the grout resulting after the curing.

[0025] In certain embodiments, the system may, under either wellbore temperatures and pressures or surface conditions, render an expanded and cured solid polymer that will bond to various materials and components. In certain embodiments, the seal is gas-tight, comprising properties of minimal fluid-loss and short transition time (<30-45 min). In certain embodiments, the cured expanded polymer grout system provides minimal shrinkage over years downhole in order to maintain the seal along the formation face.

[0026] Depending on the level of expansion (due to action of the blowing agents in the system), the resultant polymer seal may vary significantly in the ultimate density (known as the free-rise density). Conversely, the hydrostatic pressure and applied surface pressure during placement may inhibit some expansion of the grout leading to higher cured densities. In certain embodiments, the expandable polymer grout system described herein yields polymer seals that range in free rise density from about 2 to about 62 lbm/ft.sup.3. In certain embodiments, the expandable polymeric grout system has a confined density in the range of about 15 to about 40 lbm/ft.sup.3. In certain embodiments, the volume of the reaction product (i.e., the volume of the polymer seal or the expanded and cured polymer grout system) is about 2 to 13 times the initial combined volume of the liquid precursor components of the polymer grout system before reacting. In certain embodiments, the expandable polyurethane grout system has a specific gravity after expansion in the range of about 0.05 to about 0.6, about 0.09 to about 0.53, about 0.09 to about 0.30, or about 0.09 to about 0.15. In certain embodiments, the expansion of the grout system is constrained in volume by any or a mixture of a mold for injection, downhole geometry, and applied pressure.

[0027] Differences in the expandable polymer grout system may lead to differences in the curing time. Practitioners in polyurethane chemistry often report several types of time for each system (from the cream time, at which the solution color becomes turbid, through the rise time); and differences in the system, specifically the selection and concentrations of blowing agent and catalysts, can lead to differences in curing time. In certain embodiments, the expandable polymer grout system is optimized with regards to curing times to ensure that the expansion and setting does not occur until the full volume of blended components are placed at the target location.

[0028] Depending on the components of the expandable polymer grout system, the system may have higher or lower sensitivity to water that may be experienced downhole (including in the formation matrix itself). In certain embodiments, the expandable polymer grout system is designed to minimize sensitivity to downhole water (which would lead to higher expansion and lower final density).

[0029] In certain embodiments, the expandable polymer grout system, or method of injecting the system for downhole applications, is designed to minimize sensitivity to any fluids that may reside in the wellbore or formation porosity prior to injection. In certain embodiments, the methods described herein involve the injection of either a fluid or gas pre-flush to displace near wellbore fluids deeper into the formation, up the annulus, or up the wellbore, prior to injection of the polyurethane precursor blend. In surface applications in the current invention, care must be taken to be aware of material contaminants that may be adsorbed to the tools, drill string, or completion components prior to contact with grout, to minimize risk of reducing the strength of grout bonding.

[0030] Generally, the expandable polymer grout system comprises a polyurethane. The polyurethane is formed from the reaction of an isocyanate component and an organic polyol component. In certain embodiments, the reaction of the isocyanate component and the organic polyol component proceeds by combining the components in the presence of a blowing agent and, optionally, a catalyst, at a temperature of at least about 15 C. or about 20 C. to form the expandable polymer grout. In certain embodiments, the reaction of the isocyanate component and the organic polyol component proceeds by combining the components in the presence of a blowing agent and, optionally, a catalyst, at a temperature in the range of about 15 C. to about 60 C., or about 20 C. to about 40 C.

[0031] The term polyurethane, as referred to herein, is not limited to those polymers which include only urethane or polyurethane linkages. In certain embodiments, the polyurethane polymers may also include allophanate, carbodiimide, uretidinedione, and other linkages in addition to urethane linkages.

[0032] In one embodiment, an expandable polymer grout system comprises the reaction product of: (i) an isocyanate component comprising one or more isocyanate compounds; and (ii) an organic polyol component comprising one or more organic polyol compounds; in the presence of (iii) one or more blowing agents. In certain embodiments, the expandable polymer grout system further comprises one or more auxiliary components, as described herein.

[0033] In certain embodiments, the expandable polymer grout comprises about 40 to about 60 percent by weight the isocyanate component and about 40 to about 60 percent by weight the organic polyol component.

[0034] In certain embodiments, the expandable polymer grout system can be deployed (e.g., injected) into or through the wellbore as a pre-mixed system of the isocyanate component and the organic polyol component, wherein at least one of the components is slow-reacting or has delayed activation.

[0035] As referenced previously, the curing time of the expandable polymer grout system may be a factor in its application. The curing time may be controlled by the specific components selected for the expandable polymer grout system. Alternatively, the type of deployment system used to deploy the expandable polymer grout system may be selected to manage the curing time. As one example, due to the commonly rapid formation of the polyurethane product upon combining the isocyanate component and organic polyol component, it may be necessary to separate the components until they are placed at or near the target location for the grout. Preferably, the expandable polymer grout system, as well as the isocyanate and organic polyol components, each exhibit low viscosities that are in the range of 25 cP to 500 cP, more preferably in the range of 25 cP to 200 cP, and even more preferably in the range of 25 cP to 100 cP. In certain embodiments, the expandable polymer grout system can be deployed (e.g., injected) into or through the wellbore as a two-component system, wherein the isocyanate component and the organic polyol component are introduced separately. In certain embodiments, the isocyanate component and the organic polyol component are mixed downhole, for example near or at the depth that is the target location, such as for bonding a sensor downhole. Mixing of the system components proximate to the target location is described further and illustrated in connection with the examples of FIGS. 1 and 2.

[0036] In contrast, in other examples, the curing time of the expandable polymer grout system may be less of a concern. For example, in embodiments in which the expandable polymer grout system exhibits a slower curing time, the isocyanate and polyol components may be mixed at the surface of the wellbore before directing the combination to the target location within the wellbore. In other examples, the expandable polymer grout system may be deployed at or near the surface where a rapid curing time is less of a concern. Examples of these situations are described further and illustrated in connection with the examples of FIGS. 3 and 4.

[0037] In example embodiments, the isocyanate component and the organic polyol component will be in liquid form, where the viscosity of the components may vary. In other embodiments, the isocyanate component and the organic polyol component may be dissolved in inert solvents to reduce the viscosities.

[0038] In certain embodiments, the expandable polymer grout system yields a resilient/elastomeric material that can be advantageous in maintaining a bond when subjected to forces in the well system. In certain embodiments, the expandable polymer grout system, on expansion and curing, yields materials that exhibit lubricity to facilitate sliding of one component along another such as one casing along another casing.

Isocyanate Component

[0039] According to the embodiments, the isocyanate component may comprise one or more types of isocyanate compounds. In certain embodiments, the isocyanate compound is a polyisocyanate having two or more functional groups, e.g., two or more NCO functional groups. According to one embodiment, the polyisocyanate includes those represented by the formula Q(NCO), where n is a number from 2-5 and Q is an aliphatic hydrocarbon group containing 2-18 carbon atoms, a cycloaliphatic hydrocarbon group containing 5-10 carbon atoms, an aliphatic hydrocarbon group containing 8-13 carbon atoms, or an aromatic hydrocarbon group containing 6-15 carbon atoms.

[0040] Suitable isocyanates for purposes of the present invention include, but are not limited to, aliphatic and aromatic isocyanates. In certain embodiments, the isocyanate is selected from the group consisting of diphenylmethane diisocyanates (MDIs), polymeric diphenylmethane diisocyanates (pMDIs), toluene diisocyanates (TDIs), hexamethylene diisocyanates (HDIs), isophorone diisocyanates (IPDIs), ethylene diisocyanate; 1,4-tetramethylene diisocyanate; 1,12-dodecane diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3- and -1,4-diisocyanate, and mixtures of these isomers; 2,4- and 2,6-hexahydrotoluene diisocyanate and mixtures of these isomers; dicyclohexylmethane-4,4-diisocyanate 1,3- and 1,4-phenylene diisocyanate; naphthylene-1,5-diisocyanate; triphenylmethane-4,4,4-triisocyanate; polyphenyl-polymethylene-polyisocyanates of the type which may be obtained by condensing aniline with formaldehyde, followed by phosgenation (polymeric MDI); norbornane diisocyanates; m- and p-isocyanatophenyl sulfonylisocyanates; perchlorinated aryl polyisocyanates; modified polyfunctional isocyanates containing carbodiimide groups, urethane groups, allophonate groups, isocyanurate groups, urea groups, or biruret groups; polyfunctional isocyanates obtained by telomerization reactions; polyfunctional isocyanates containing ester groups; and polyfunctional isocyanates containing polymeric fatty acid groups; and combinations thereof.

[0041] Suitable isocyanates for use in the expandable polymer grouts described herein include but are not limited to: toluene diisocyanate; 4,4-diphenylmethane diisocyanate; m-phenylene diisocyanate; 1,5-naphthalene diisocyanate; 4-chloro-1; 3-phenylene diisocyanate; tetramethylene diisocyanate; hexamethylene diisocyanate; 1,4-dicyclohexyl diisocyanate; 1,4-cyclohexyl diisocyanate, 2,4,6-toluylene triisocyanate, 1,3-diisopropylphenylene-2,4-diisocyanate; 1-methyl-3,5-diethylphenylene-2,4-diisocyanate; 1,3,5-triethylphenylene-2,4-diisocyanate; 1,3,5-triisoproply-phenylene-2,4-diisocyanate; 3,3-diethyl-bisphenyl-4,4-diisocyanate; 3,5,3,5-tetraethyl-diphenylmethane-4,4-diisocyanate; 3,5,3,5-tetraisopropyldiphenylmethane-4,4-diisocyanate; 1-ethyl-4-ethoxy-phenyl-2,5-diisocyanate; 1,3,5-triethyl benzene-2,4,6-triisocyanate; 1-ethyl-3,5-diisopropyl benzene-2,4,6-triisocyanate and 1,3,5-triisopropyl benzene-2,4,6-triisocyanate. Other suitable rigid polyurethane foams can also be prepared from aromatic diisocyanates or isocyanates having one or two aryl, alkyl, arakyl or alkoxy substituents wherein at least one of these substituents has at least two carbon atoms.

[0042] In certain embodiments, the isocyanate has an NCO content of from about 25 to about 33 weight percent; a nominal functionality of from about 2 to about 3.5; and a viscosity of from about 60 to about 2000 cps, or about 200 to about 700 cps, at 25 C. (77 F.).

[0043] In certain embodiments, the isocyanate components comprise polymeric diphenylmethane diisocyanate.

[0044] In certain embodiments, the isocyanate component may be an isocyanate prepolymer. An isocyanate prepolymer comprises a reaction product of an isocyanate and a polyol and/or a polyamine. The isocyanate used in the prepolymer can be any isocyanate as described above. The polyol used to form the prepolymer is typically selected from the group of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butane diol, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, biopolyols, and combinations thereof. The polyamine used to form the prepolymer is typically selected from the group of ethylene diamine, toluene diamine, diaminodiphenylmethane and polymethylene polyphenylene polyamines, aminoalcohols, and combinations thereof. Suitable non-limiting examples of aminoalcohols include ethanolamine, diethanolamine, triethanolamine, and combinations thereof.

[0045] In certain embodiments, the isocyanate compounds may also be provided in a chemically blocked state, whereby a reaction to deblock the isocyanate may happen prior to polymerization, optionally under downhole conditions, to expose the active isocyanate functionalities. The exposed isocyanates will then react with the organic alcohol groups of the polyol to form the urethane bonds. As such, blocked isocyanate compounds can be used to prevent premature reaction of the isocyanate component with the organic polyol component. Blocked isocyanates regenerate the isocyanate function through heating. Typical unblock temperatures range between 65 to 200 C., depending on the isocyanate structure and blocking agent.

[0046] In certain embodiments, the isocyanate component comprises blocked isocyanate compounds, or an isocyanate compound that has been protected with a blocking agent.

[0047] Suitable isocyanate blocking agents may include alcohols (including phenols), ethers, phenols, malonate esters, methylenes, aceto acetate esters, lactams, oximes, ureas, bisulphites, mercaptans, triazoles, pyrazoles, secondary amines, glycolic acid esters, acid amides, aromatic amines, imides, diaryl compounds, imidazoles, carbamic acid esters, or sulfites.

[0048] Exemplary phenolic blocking agents include phenol, cresol, xylenol, chlorophenol, ethylphenol and the like.

[0049] Lactam blocking agents include gamma-pyrrolidone, laurinlactam, epsilon-caprolactam, delta-valerolactam, gamma-butyrolactam, beta-propiolactam and the like.

[0050] Methylene blocking agents include acetoacetic ester, ethyl acetoacetate, acetyl acetone and the like.

[0051] Oxime blocking agents include formamidoxime, acetaldoxime, acetoxime, methyl ethylketoxine, diacetylmonoxime, cyclohexanoxime and the like.

[0052] Mercaptan blocking agent include butyl mercaptan, hexyl mercaptan, t-butyl mercaptan, thiophenol, methylthiophenol, ethylthiophenol and the like.

[0053] Acid amide blocking agents include acetic acid amide, benzamide and the like. Imide blocking agents include succinimide, maleimide and the like.

[0054] Amine blocking agents include xylidine, aniline, butylamine, dibutylamine diisopropyl amine and benzyl-tert-butyl amine and the like.

[0055] Imidazole blocking agents include imidazole, 2-ethylimidazole and the like.

[0056] Imine blocking agents include ethyleneimine, propyleneiniine and the like.

[0057] Triazole blocking agents include 1,2,4-triazole, 1,2,3-benzotriazole, 1,2,3-tolyl triazole and 4,5-diphenyl-1,2,3-triazole.

[0058] Alcohol blocking agents include methanol, ethanol, propanol, butanol, amyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, benzyl alcohol, methyl glycolate, butyl glycolate, diacetone alcohol, methyl lactate, ethyl lactate and the like. Additionally, any suitable aliphatic, cycloaliphatic or aromatic alkyl monoalcohol may be used as a blocking agent in accordance with the present disclosure. For example, aliphatic alcohols, such as methyl, ethyl, chloroethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, 3,3,5-trimethylhexyl, decyl, and lauryl alcohols, and the like may be used. Suitable cycloaliphatic alcohols include, for example, cyclopentanol, cyclohexanol and the like, while aromatic-alkyl alcohols include phenyl carbinol, methylphenylcarbinol, and the like.

[0059] Dicarbonylmethane blocking agents include malonic acid esters such as diethyl malonate, dimethyl malonate, di(iso)propyl malonate, di(iso)butyl malonate, di(iso)pentyl malonate, di(iso)hexyl malonate, di(iso)heptyl malonate, di(iso)octyl malonate, di(iso)nonyl malonate, di(iso)decyl malonate, alkoxyalkyl malonates, benzylmethyl malonate, di-tert-butyl malonate, ethyl-tert-butyl malonate, dibenzyl malonate; and acetylacetates such as methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetate and alkoxyalkyl acetoacetates; cyanacetates such as cyanacetic acid ethylester; acetylacetone; 2,2-dimethyl-1,3-dioxane-4,6-dione; methyl trimethylsilyl malonate, ethyl trimethylsilyl malonate, and bis(trimethylsilyl) malonate. Malonic or alkylmalonic acid esters derived from linear aliphatic, cycloaliphatic, and/or arylalkyl aliphatic alcohols may also be used. Such esters may be made by alcoholysis using any of the above-mentioned alcohols or any monoalcohol with any of the commercially available esters (e.g., diethylmalonate). For example, diethyl malonate may be reacted with 2-ethylhexanol to obtain the bis-(2-ethylhexyl)-malonate. It is also possible to use mixtures of alcohols to obtain the corresponding mixed malonic or alkylmalonic acid esters. Suitable alkylmalonic acid esters include: butyl malonic acid diethylester, diethyl ethyl malonate, diethyl butyl malonate, diethyl isopropyl malonate, diethyl phenyl malonate, diethyl n-propyl malonate, diethyl isopropyl malonate, dimethyl allyl malonate, diethyl chloromalonate, and dimethyl chloro-malonate.

[0060] Other isocyanate blocking agents are described in, for example, U.S. Pat. Nos. 6,288,176, 5,559,064, 4,637,956, 4,870,141, 4,767,829, 5,108,458, 4,976,833, and 7,157,527, U.S. Patent Application Publication Nos. 20050187314, 20070023288, 20070009750, 20060281854, 20060148391, 20060122357, 20040236021, 20020028932, 20030194635, and 20030004282, each of which is incorporated herein by reference. Mixtures of the above-listed isocyanate blocking agents may also be used.

[0061] Blocked polyisocyanate compounds may include, for example, polyisocyanates having at least two tree isocyanate groups per molecule, where the isocyanate groups are blocked with an above-described isocyanate blocking agent.

[0062] Blocked isocyanates may be prepared by reaction of one of the above-mentioned isocyanate compounds and a blocking agent by a conventionally known appropriate method.

[0063] In other embodiments, the blocked isocyanates used in embodiments disclosed herein may be any isocyanate where the isocyanate groups have been reacted with an isocyanate blocking agent so that the resultant capped isocyanate is stable to active hydrogens at room temperature but reactive with active hydrogens at elevated temperatures, such as between about 65 C. to 200 C.

[0064] Blocked polyisocyanate compounds are typically stable at room temperature. When heated to a temperature about the minimum unblocking temperature, the blocking agent is dissociated to regenerate the free isocyanate groups, which may readily react with hydroxyl groups of the organic polyol compounds.

[0065] As an alternative to an external or conventional blocking agent, the isocyanates of the present disclosure may be internally blocked. The term internally blocked, as used herein, indicates that there are uretdione groups present which unblock at certain temperatures to free the isocyanate groups for cross-linking purposes. Isocyanate dimers (also referred to as uretdiones) may be obtained by dimerizing diisocyanates in the presence of phosphine catalysts. In certain embodiments, the blocking agent is selected from the group consisting of: methylethylcetoxime (MEKO), diethyl malonate (DEM), 3,5-dimethylpyrazole (DMP).

Organic Polyol Component

[0066] According to the embodiments, the organic polyol component may comprise one or more types of organic polyol compounds, which are reactive with the isocyanate compounds. Organic polyol compounds suitable for use in the present invention may include, but are not limited to, polyether polyols, polyester polyols, polycarbonate polyols, and biorenewable polyols. Such polyols may be used alone or in suitable combination as a mixture.

[0067] General functionality of polyols used in the present invention is between about 2 to about 5, or about 2 to about 3. The weight average molecular weight of polyols may be between about 500 and about 10,000, or about 500 and about 5,000 g/mol.

[0068] The proportion of the organic polyol compounds is generally of between about 10 and about 80% by weight, preferably between about 20 and about 50% based of the expandable polymer grout system.

[0069] Polyether polyols for use in the present invention include alkylene oxide polyether polyols such as ethylene oxide polyether polyols and propylene oxide polyether polyols and copolymers of ethylene and propylene oxide with terminal hydroxyl groups derived from polyhydric compounds, including diols and triols; for example, ethylene glycol, propylene glycol, 1,3-butane diol, 1,4-butane diol, 1,6-hexane diol, neopentyl glycol, diethylene glycol, dipropylene glycol, pentaerythritol, glycerol, diglycerol, trimethylol propane, and similar low molecular weight polyols.

[0070] Polyester polyols for use in the present invention include, but are not limited to, those produced by reacting a dicarboxylic acid with an excess of a diol, for example, adipic acid with ethylene glycol or butanediol, or reaction of a lactone with an excess of a diol such as caprolactone with propylene glycol. In addition, polyester polyols for use in the present invention may also include: linear or lightly branched aliphatic (e.g. adipates) polyols with terminal hydroxyl group; low molecular weight aromatic polyesters; polycaprolactones; polycarbonate polyol. Those linear or lightly branched aliphatic (e.g. adipates) polyols with terminal hydroxyl group are produced by reacting a dicarboxyl acids with an excess of diols, triols and their mixture; those dicarboxyl acids include, but are not limited to, for example, adipic acid, AGS mixed acid; those diols, triols include, but are not limited to, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butane diol, 1,6-hexane diol, glycerol, trimethylolpropane and pentaerythritol.

[0071] In certain embodiments, the organic polyol component is selected from aromatic polyester polyol and an aliphatic polyester polyol.

[0072] The aromatic polyester polyol is typically formed via the condensation of a glycol and a dicarboxylic acid or acid derivative. The functionality, structure, and molecular weight of the polyester polyol can be varied to tailor the processing characteristics and physical properties of the expanded polymer grout system to a particular application. In certain embodiments, the aromatic polyester polyol has a functionality of greater than 2 or about 2 to about 5 and a weight-average molecular weight of from 500 to 5,000 g/mol, or about 1,000 to 3,000 g/mol. In certain embodiments, the aromatic polyester polyol has a hydroxyl value of from 100 to 500 mg KOH/g. In certain embodiments, the aromatic polyester polyol has a viscosity at 25 C. of from about 200 to about 2,000 cP. In certain embodiments, the aromatic polyester polyol has a specific gravity of about 1.0 to about 1.2 g/cm.sup.3. In certain embodiments, the aromatic polyester polyol is present in the organic polyol component in an amount of from about 25 to about 100 parts by weight, based on 100 parts by weight of the total weight of the polyols present in the organic polyol component.

[0073] The aliphatic polyester polyol is typically formed via the condensation of a glycol and a dicarboxylic acid or acid derivative. In certain embodiments, the aliphatic polyester polyol has a functionality of greater than 2 or about 2 to about 5 and a weight-average molecular weight of from 500 to 5,000 g/mol, or about 1,000 to 3,000 g/mol. In certain embodiments, the aliphatic polyester polyol has a hydroxyl value of from 20 to 400 mg KOH/g. In certain embodiments, the aliphatic polyester polyol has a viscosity at 25 C. of from about 200 to about 2,000 cP. In certain embodiments, the aliphatic polyester polyol has a specific gravity of about 1.0 to about 1.2 g/cm.sup.3. In certain embodiments, the aliphatic polyester polyol is present in the organic polyol component in an amount of from about 2 to about 100 parts by weight, based on 100 parts by weight of the total weight of the polyols present in the organic polyol component.

[0074] In certain embodiments, one or more aliphatic polyester polyol and one or more aromatic polyester polyol are both present in the organic polyol component, for example in a ratio of from 1:5 to 1:15.

[0075] Polycarbonate polyols are derived from carbonic acid that can be produced through the polycondensation of diols with phosgene, although transesterification of diols, commonly hexane diol, with a carbonic acid ester, such as diphenylcarbonate.

[0076] Biorenewable polyols suitable for use in the present invention include castor oil, sunflower oil, palm kernel oil, palm oil, canola oil, rapeseed oil, soybean oil, corn oil, peanut oil, olive oil, algae oil, and mixtures thereof.

Blowing Agents, Catalysts and Other Auxiliary Components

[0077] Typically, the isocyanate component and the organic polyol component are reacted in the presence of a blowing agent to form the expandable polymer grout. The blowing agent may be a physical blowing agent, a chemical blowing agent, or a combination of a physical blowing agent and a chemical blowing agent.

[0078] The term physical blowing agent refers to blowing agents that do not chemically react with the isocyanate and/or the organic polyol component. The physical blowing agent can be a gas or liquid. The liquid physical blowing agent typically evaporates into a gas when heated, and typically returns to a liquid when cooled. Examples of physical blowing agents include volatile liquids such as chlorofluorocarbons, partially halogenated hydrocarbons or non-halogenated hydrocarbons like propane, n-butane, isobutane, n-pentane, isopentane cyclopentane and/or neopentane. In a particular embodiment, the blowing agent comprises, or consists essentially of, cyclopentane.

[0079] The term chemical blowing agent describes blowing agents which chemically react with the isocyanate or with other components to release a gas for foaming. Examples of chemical blowing agents include water, gaseous compounds such as nitrogen or carbon dioxide, gas (e.g. CO.sub.2) forming compounds such as azodicarbonamides, carbonates, bicarbonates, citrates, nitrates, borohydrides, carbides such as alkaline earth and alkali metal carbonates and bicarbonates e.g. sodium bicarbonate and sodium carbonate, ammonium carbonate, diaminodiphenylsulphone, hydrazides, malonic acid, citric acid, sodium monocitrate, ureas, azodicarbonic methyl ester, diazabicylooctane and acid/carbonate mixtures. In a particular embodiment, the blowing agent comprises, or consists essentially of, water.

[0080] In certain embodiments, the total amount of the blowing agents present in the reaction mixture or in the organic polyol component in an amount of from about 1 to about 30, or about 10 to about 25, parts by weight, based on 100 parts by weight of the organic polyols present in the organic polyol component.

[0081] In one embodiment, the expandable polymer grout system comprises a physical blowing agent. In one embodiment, the expandable polymer grout system comprises a chemical blowing agent. In one embodiment, the expandable polymer grout system comprises both a physical blowing agent and a chemical blowing agent.

[0082] In one embodiment, the expandable polymer grout system comprises one or more catalysts. In certain embodiments, the one or more catalysts are present in the organic polyol component to catalyze the reaction between the isocyanate and the polyols. The catalyst may include any suitable catalyst or mixtures of catalysts known in the art. Examples of suitable catalysts include, but are not limited to, gelation catalysts, e.g., amine catalysts in dipropylene glycol; blowing catalysts, e.g., bis(dimethylaminoethyl)ether in dipropylene glycol; and metal catalysts, e.g., tin, bismuth, lead, etc. One non-limiting example of a suitable catalyst is N,N-dimethylcyclohexylamine.

[0083] In one embodiment, the expandable polymer grout system comprises one or more surfactants. The surfactant typically supports homogenization of the blowing agent and the polyol and regulates a cell structure of the expandable polymer grout. In certain embodiments, the one or more surfactants are present in the organic polyol component. The surfactant may include any suitable surfactant or mixtures of surfactants known in the art. Non-limiting examples of suitable surfactants include various silicone surfactants, salts of sulfonic acids, e.g. alkali metal and/or ammonium salts of oleic acid, stearic acid, dodecylbenzene- or dinaphthylmethane-disulfonic acid, and ricinoleic acid, foam stabilizers such as siloxaneoxyalkylene copolymers and other organopolysiloxanes, oxyethylated alkyl-phenols, oxyethylated fatty alcohols, paraffin oils, castor oil, castor oil esters, and ricinoleic acid esters, and cell regulators, such as paraffins, fatty alcohols, and dimethylpolysiloxanes. One specific, non-limiting example of a surfactant is a silicone-polyether block copolymer.

[0084] The expandable polymer grout system, or organic polyol component, may optionally include one or more additional auxiliary components. Suitable additives for purposes of the instant disclosure include, but are not limited to, chain-extenders, crosslinkers, chain-terminators, processing additives, adhesion promoters, anti-oxidants, defoamers, anti-foaming agents, water scavengers, molecular sieves, fumed silicas, ultraviolet light stabilizers, fillers, thixotropic agents, silicones, colorants, inert diluents, plasticizers, silane coupling agent, cell stabilizers, fillers, or any combination thereof.

[0085] In one embodiment, the proportion of the auxiliary components present in the expandable grout composition is between about 5 and about 80 percent by weight, or about 10 and about 60 percent by weight, of the total weight of the expandable polymer grout system.

[0086] In certain embodiments, the two component systems have the isocyanate delivered as an isolated component (not combined with other reactants or additives) and the organic polyol component may be pre-blended with blowing agents, catalysts and other auxiliary components, as described above.

[0087] In certain embodiments, the performance properties of the expandable polymer grout system may be adjusted through the addition of the blowing agents, catalysts and auxiliary components.

[0088] In certain embodiments, it may be desirable to combine or mix the expandable polymer grout system with other functional materials, such as fluid-loss control particulates to mitigate premature or excessive loss of the liquid polymer into the formation or annulus prior to the polymer setting up or crosslinking in the desired locations. In certain embodiments, the expandable polymer grout system may be combined with cement such as to enhance certain properties of the cement. Combinations with materials such as cement may provide enhanced material properties for operations such as forming an improved seal along a sand screen. Prior to the polymer crosslinking or otherwise reacting, the disclosed polymers may exhibit flow properties that are more Newtonian and less viscous than liquid cement, thereby flowing into tighter flowpaths than cement alone otherwise might.

Methods of Use

[0089] The expandable polymer grout system according to the embodiments described herein may be deployed to form a grout that bonds to one or more materials or components associated with a well system. Methods of deployment will depend on both the characteristics and reactivity of the expandable polymer grout system as well as the intended usage downhole.

[0090] In certain embodiments, a method for creating a grout bond from an expandable polymer grout system, comprises: [0091] (I) providing an expandable polymer grout system to a target location within or through a wellbore, wherein the expandable polymer grout system comprises: (i) an isocyanate component comprising one or more isocyanate compounds; and (ii) an organic polyol component comprising one or more organic polyol compounds; in the presence of (iii) one or more blowing agents; [0092] (II) combining components (i), (ii) and (iii) of the expandable polymer grout system to facilitate the polymerization reaction to form the expandable polymer grout at the target location; and (III) allowing the expandable polymer grout to cure at the target location forming a grout bond. In certain embodiments, a grout bond formed from the system according to the embodiments may be formed at targeted sites or zones. For example, a grout bond formed from the systems according to the embodiments may be set at a target location or target zone of a specific depth in a well. To provide a grout bond at a specific depth, spotting of the polyurethane precursors may achieved with a deployment system, which may include a mixer, cannisters containing components of the system, coiled tubing, coiled hose(s), custom umbilical, or other conduit to target the solution placement.

[0093] In certain embodiments, the isocyanate component and organic polyol component are injected through a conduit system referred to as dual-string injection, where each component is injected through an isolated tube, are combined optionally in a mixing chamber (optionally between packers or other barriers), and the combined precursors are then injected from the mixing chamber to the target location requiring a grout bond. This injection will be followed by a static curing time, to allow the expandable polymer to first expand and then to cure into the fully polymerized (optionally hardened) state. The curing may optionally be carried out under additional pressure applied by a working fluid through both the workstring and/or the annulus (possibly to control the degree of expansion and/or density or to further squeeze the precursor blend into the annulus). Injection of the precursors through the mixing chamber may optionally be followed by a flush stage of an inert fluid or gas (that does not participate in the polymerization/curing process) prior to expansion and curing to purge and clean the mixing chamber.

[0094] In certain embodiments, the isocyanate and polyol components of the expandable polymeric grout are injected into the hydrocarbon well or wellbore separately.

[0095] In certain embodiments, the components of the expandable polymer grout are injected into the hydrocarbon well through dual-string injection or through isolated tubes.

[0096] In certain embodiments, the components of the expandable polymer grout are combined in a mixing chamber prior to injection into the region in which a grout bond is to be formed.

[0097] The expandable polymer grout system can be used in methods of creating a grout bond within or through a wellbore. In certain embodiments, the method for creating a grout bond within a wellbore comprises: (I) providing an expandable polymer grout system to a target location, wherein the expandable polymer grout system comprises: (i) an isocyanate component comprising one or more isocyanate compounds; and (ii) an organic polyol component comprising one or more organic polyol compounds; in the presence of (iii) one or more blowing agents; (II) combining components (i), (ii) and (iii) of the expandable polymer grout system to facilitate the polymerization reaction to form the expandable polymer grout at the target location and (III) allowing the expandable polymer grout to cure at the target location to form the grout bond.

[0098] In certain embodiments, the initial combining of the components may be conducted at the surface of the well, prior to being pumped into the wellbore, while in other embodiments the components will be combined inside the wellbore. In certain embodiments, the target location is at an open hole location within the wellbore where no casing is present. In certain embodiments, the target location is at a location accessed through the wellbore.

[0099] In certain embodiments, the method comprises creating a grout bond during at least one of a drilling operation, a casing operation, a liner operation, a completion operation, a recompletion operation, a primary cementing operation, a staged cementing operation, a production operation, or an injection operation.

Examples of Deploying Expandable Polymer Grout in Well Systems

[0100] FIGS. 1 through 4 illustrate examples of well systems in which the previously described expandable polymer grout systems can be applied to create a grout that bonds to one or more materials or components. The examples of FIGS. 1 through 4 illustrate various methods for deploying an expandable polymer grout system in connection with a well system. The well systems of FIGS. 1 through 4 are illustrative examples and the polymer grout described herein can be used in other applications as well. Moreover, the different methods illustrated in FIGS. 1 through 4 are not mutually exclusive in that one of skill in this field will understand that aspects of one method may be combined with aspects of another method illustrated in the figures. The well systems illustrated in FIGS. 1 through 4 are not drawn to scale so that more relevant aspects of the disclosure may be more clearly illustrated.

[0101] Referring to FIG. 1, a well system 150 in a subterranean formation 178 is illustrated. The well system 150 includes a wellbore 151 with a wellbore opening at surface 101. The surface 101 can be ground level for an on-shore application, the sea floor for an off-shore application, or a working surface at which operations are deployed such as a rig, a drilling rig, or a vessel. While not illustrated in FIG. 1, field equipment may be located at or above the surface 101, including but not limited to one or more of a circulation unit, a derrick, a tool pusher, a clamp, a tong, drill pipe, a drill bit, isolator subs, tubing housing, a power source, casing pipe, a coiled tubing unit, intervention/stimulation vessel, and a wireline tool. Well system 150 includes a cylindrical tubing 138 that may be a drill string, a work string, a production tubing, or other type of tubing used in connection with a well system. The tubing 138 extends from the surface 101 to a depth of the wellbore 151. An annular packer 139 is located in the annular space between the outer surface of the tubing 138 and the formation 178.

[0102] In the example of FIG. 1, an obstruction 142 is located at a depth within the wellbore 151. The obstruction may be any type of material or component that is to be removed from the wellbore 151. As examples, the obstruction may be a tool, a drill bit, a collar, a packer, a section of pipe, or a component that has broken loose from a piece of equipment. The removal of an obstruction from a wellbore can be referred to generally as a retrieval operation, although, in the industry, the removal is commonly referred to as a fishing operation. A retrieval or fishing operation typically uses a retrieval tool to retrieve the obstruction from the wellbore. A variety of retrieval tools can be used, including but not limited to a spear, a hook, an overshot, and a grabbing tool. Retrieval operations often encounter challenges when the retrieval tool is unable to adequately grab or bind to the obstruction, causing the obstruction to slip from the retrieval tool and thwarting the retrieval operation. When retrieval operations encounter challenges with retrieving the obstruction, such challenges cause delays and interfere with the operation of the well.

[0103] The expandable polymer grout systems described herein can be used to improve such retrieval operations. The properties of the expandable polymer grout systems make them advantageous for improving retrieval operations. In particular, the ability to bond to a variety of materials and components is an advantage of the expandable polymer grout systems described herein. Additionally, the expanding nature of the expandable polymer grout systems allows them to expand around or through features of an obstruction thereby improving the ability to bond to the obstruction. Accordingly, using expandable polymer grout systems with a retrieval system can improve the ability to retrieve an obstruction from a wellbore.

[0104] As further illustrated in FIG. 1, a retrieval system 122 is deployed into the wellbore 151 to perform a retrieval operation to retrieve the obstruction 142. A support line 118 attached to field equipment (not shown for simplicity) can lower the retrieval system 122 down into the wellbore 151 to a target location 134 proximate to the obstruction 142. The retrieval system 122 can include a retrieval tool 140 that engages the obstruction 142. The example retrieval tool 140 is a grabbing tool, but other types of retrieval tools may also be used. Once the retrieval tool 140 engages the obstruction 142, the expandable polymer grout system can be deployed. Once deployed, the expandable polymer grout flows from the retrieval system 122 and contacts the retrieval tool 140 and the obstruction 142. The expandable polymer grout system is allowed to cure so that the grout bonds to retrieval tool 140 and the obstruction 142. The grout bond assists the retrieval tool in maintaining a grip on the obstruction 142. After curing and with the grout bond in place, the retrieval system is retracted from the wellbore 151 with the obstruction 142, thereby clearing the obstruction 142 from the wellbore 151.

[0105] The retrieval system 122 can deploy the expandable polymer grout system using one of several different mechanisms. FIG. 1 illustrates one potential mechanism for deploying the expandable polymer grout system. The reactions between most polyurethane precursors are often so rapid that mixing the components of the expandable polymer grout system at the surface of the well system and injecting them downhole to the target location would likely be unsuccessful as the grout expansion and curing would likely occur before reaching the target location. Accordingly, the retrieval system 122 is directed to placing the expandable polymer grout system at the target location and within the required time to allow the expandable polymer grout system to expand and cure into the grout bond at the target location 134 when the retrieval tool 140 has engaged the obstruction 142.

[0106] The example retrieval system 122 of FIG. 1 uses a cannister system 120 to deploy the expandable polymer grout. The cannister system 120 is attached to the retrieval system 122 and can be lowered into and raised from the wellbore 151 by support line 118 or by another tubular string. The cannister system 120 comprises a first compartment containing an isocyanate component and a second compartment containing an organic polyol component. As explained previously, the organic polyol component may be pre-blended with blowing agents, catalysts, and other auxiliary components.

[0107] At the time of deployment, the cannister system 120 can be actuated to combine the isocyanate component and the organic polyol component of the expandable polymer grout system. The actuation of the cannister system can be triggered, for example, by a slickline or e-line extending down into the wellbore 151, by a mechanical trigger and timer, or by a change in pressure. The mixed components of the expandable polymer grout system form a grout 132 that exits the cannister system 120 through an outlet at the bottom of the cannister system 120 and flows into a tailpipe 130 attached to the bottom of the cannister system 120. In certain embodiments, the cannister system can include a pressurized fluid that applies pressure to the grout encouraging it to exit the cannister system 120.

[0108] The grout 132 flows through the tailpipe 130 and contacts the retrieval tool 140 and the obstruction 142. As another optional feature, the cannister system 120 can include a lubricant that facilitates the flow of the grout through the tailpipe 130 and to the retrieval tool 140 and the obstruction 142. The lubricant can reduce the likelihood that the grout bonds to other unintended components such as the tailpipe 130 or other downhole equipment. An advantage of the retrieval system 122 illustrated in FIG. 1 is that the expandable polymer grout system components are mixed proximate to the target location 134 and engage the retrieval tool 140 and the obstruction 142 before the grout 132 cures and forms a hardened polymer seal. The retrieval system 122 and the cannister system 120 can remain in the same position while grout 132 expands and cures to form a bond with the retrieval tool 140 and the obstruction 142. After the grout 132 has bonded to the retrieval tool 140 and the obstruction 142, the retrieval system 122 and the obstruction 142 are retracted from the wellbore 151 thereby clearing the obstruction 142 from the wellbore 151.

[0109] While not illustrated in FIG. 1, optionally, in connection with inserting the retrieval system 122 into the well system 150, barriers can be used to isolate the obstruction 142 and the target location 134. Before deploying the expandable polymer grout system, a lower barrier can be placed within the tubing 138 below the obstruction 142 and an upper barrier can be placed within the tubing 138 above the obstruction 142. The upper and lower barriers can be any of a variety of barriers used in well completions including a bridge plug, packer, cement retainer, or other physical barrier. The purpose of the upper and lower barriers is to prevent the expandable polymer grout system from flowing away from the target location 134 before curing bonds the grout to the retrieval tool 140 and the obstruction 142. In alternate embodiments of the retrieval system 122, the upper and/or lower barrier may be unnecessary.

[0110] The cannister system is one example of a mechanism for deploying the grout with the retrieval system 122. In other embodiments, the grout can be deployed using other equipment. For example, the components of the expandable polymer grout system can be conveyed via separate conduits of a conduit system from the surface 101 to the target location 134 where the components are mixed with a mixer. Once the components are mixed at the target location 134, the expandable polymer grout system can be directed to the retrieval tool 140 and the obstruction 142 where the grout bonds to each. The use of a conduit system for deploying the expandable polymer grout system is illustrated in greater detail in the embodiment in FIG. 2.

[0111] Referring now to FIG. 2, another application of the expandable polymer grout systems is illustrated. Specifically, FIG. 2 illustrates using the expandable polymer grout system to form a grout bond that attaches a sensor to downhole equipment. It is common to deploy a variety of sensors in well systems. However, the harsh environmental conditions often encountered within a well present challenges with respect to securely attaching such sensors to downhole equipment. The harsh environmental conditions can include extreme temperatures and pressures, corrosive fluids, and erosive slurries containing solids. Accordingly, the unique characteristics of the expandable polymer grout systems described herein can provide advantages with respect to securing sensors to downhole equipment.

[0112] In certain applications, the expandable polymer grout system can be deployed at the surface of the well system to secure a sensor to equipment before the equipment with the sensor is lowered into a wellbore. Alternatively, as illustrated in FIG. 2, the expandable polymer grout system can be deployed down into a wellbore to bond a sensor to a piece of equipment that is already located in the wellbore.

[0113] Referring to FIG. 2, a well system 250 in a subterranean formation 278 is illustrated. The well system 250 includes a wellbore 251 with a wellbore opening at surface 201. The surface 201 can be ground level for an on-shore application, the sea floor for an off-shore application, or a work surface at which operations are deployed such as a rig, a drilling rig, or a vessel. While not illustrated in FIG. 2, field equipment may be located at or above the surface 201, including but not limited to one or more of a circulation unit, a derrick, a tool pusher, a clamp, a tong, drill pipe, a drill bit, isolator subs, tubing housing, a power source, casing pipe, a coiled tubing unit, intervention/stimulation vessel, and a wireline tool. Well system 250 includes a cylindrical tubing 238 that may be a drill string, a work string, a production tubing, or other type of tubing used in connection with a well system. The tubing 238 extends from the surface 201 to a depth of the wellbore 251. An annular packer 239 is located in the annular space between the outer surface of the tubing 238 and the formation 278.

[0114] In the example of FIG. 2, a sensor 244 is attached at a target location 234 to an outer surface of the tubing 238 in the annulus between the tubing 238 and the formation 278. In other examples, sensors can be deployed at other locations within the well system 250. A deployment system 222 is used to place the expandable polymer grout system in the wellbore 251 for securing the sensor 244. The deployment system may also place the sensor 244 at the target location or other equipment may be used for placing the sensor 244.

[0115] The deployment system 222 can have a variety of configurations. The example deployment system 222 of FIG. 2 includes a first conduit 206 that delivers an isocyanate component through the wellbore to a mixer 220. The isocyanate flows from a tank 202 and is pumped via a pump 204 through the first conduit 206. A check valve at the end of the first conduit 206 controls the flow of the isocyanate into the mixer 220. The example system of FIG. 2 also includes a second conduit 214 that delivers an organic polyol component through the wellbore to the mixer 220. The organic polyol component flows from a tank 210 and is pumped via a pump 212 through the second conduit 214. Together, the first conduit 206 and second conduit 214 may be referred to as a conduit system. While the first conduit 206 and second conduit 214 are illustrated as separated components in FIG. 2, in other examples they may be combined into a single tubular and may be concentrically aligned in a coaxial arrangement. A check valve at the end of the second conduit 214 controls the flow of the organic polyol component into the mixer 220. As explained previously, the organic polyol component may be pre-blended with blowing agents, catalysts, and other auxiliary components before the component is pumped into the wellbore via pump 212. The tanks 202 and 210 can be stationary tanks located at the surface 201 of the well system 250 or can be mobile tanks mounted on vehicles.

[0116] In certain example embodiments, the mixer 220 with the attached first conduit 206 and attached second conduit 214 can be raised and lowered into the wellbore by an optional support line 218 or on a tubular string. In the example illustrated in FIG. 2, the mixer 220 is a static mixer with helical internal surfaces that mix the isocyanate component and the organic polyol component as they flow into the mixer 220 from the first conduit 206 and the second conduit 214. As the isocyanate component and the organic polyol component of the expandable polymer grout system combine within the mixer, they react and form the grout 232. The grout 232 exits the mixer 220 through an outlet at the bottom of the mixer 220 and flows into a tailpipe 230 attached to the bottom of the mixer 220. As illustrated in the example of FIG. 2, the tailpipe 230 preferably has a vertical segment and a generally horizontal segment that directs the grout toward the target location 234 and the sensor 244. The shape of the tailpipe can be modified to accurately direct the grout to the desired target location. In certain embodiments, the deployment system 222 can include a fluid to apply pressure to deploy the grout 232 at the target location 234. Optionally, the deployment system 222 can include a lubricant that facilitates the flow of the grout 232 to the target location 234 and inhibits the grout 232 from adhering to the tailpipe 230 or other unintended downhole equipment.

[0117] An advantage of the deployment system 222 illustrated in FIG. 2 is that the expandable polymer grout system components are mixed proximate to the target location 234 and flow to the sensor 244 before the grout cures and forms a hardened grout bond. As non-limiting examples, it is preferred that the components of the expandable polymer grout system are mixed within the wellbore and within a distance of 50 feet from the target location 234, more preferably within 40 feet of the target location 234, and still more preferably within 30 feet of the target location 234. The components of FIG. 2 are not drawn to scale. Nonetheless, as one example, the height of the mixer 220 can be between 8 and 20 inches and the height of the tailpipe 230 can be between 5 feet and 30 feet. Taking into account these typical dimensions and the speed of the pumps 204 and 212, the mixture can be combined at the mixer 220 and flow through the tailpipe 230 to the target location 234 within a few minutes so that the grout is in the desired position at the sensor 244 where it will bond the sensor 244 to the tubing 238.

[0118] In alternate embodiments of the well system 250, the expandable polymer grout system may be deployed to the target location 234 using other mechanisms. For example, the cannister system described in association with FIG. 1 may be used in place of the conduit system and mixer illustrated in FIG. 2. In another example, where the components of the expandable polymer grout system are configured to polymerize at a slower rate, the components may be mixed at the surface and pumped in combination downhole in a single conduit to the target location where they will bond the sensor to the downhole equipment.

[0119] Referring now to FIG. 3, another application of the expandable polymer grout systems is illustrated. Specifically, FIG. 3 illustrates using the expandable polymer grout system to form a grout bond that secures a casing centralizer to an exterior surface of a casing. In this application, as described further below, operations are performed at the surface whereby the expandable polymer grout system is applied to the casing centralizer and the casing before the casing with the casing centralizer are inserted into the wellbore. The wellbore is illustrated in FIG. 3 for context. A casing centralizer is typically cylindrical in shape and is placed around the exterior surface of a casing joint or segment before the casing is placed into a wellbore. The casing centralizer is used to maintain the position of the casing in a wellbore relative to another surrounding casing. However, the harsh environmental conditions often encountered within a well present challenges with respect to maintaining the casing centralizer securely attached to the casing. The harsh environmental conditions can include extreme temperatures and pressures, corrosive fluids, and erosive slurries containing solids. Accordingly, the unique characteristics of the expandable polymer grout systems described herein can provide advantages with respect to securing a casing centralizer to a casing. And the ability to bind centralizers to casing by injecting expandable grout to bind the centralizers on-site adds versatility and flexibility to the operation of casing the well.

[0120] In a preferred embodiment, the expandable polymer grout system is deployed at the surface of the well system to secure a casing centralizer to a casing before the casing is lowered into a wellbore. FIG. 3 illustrates a well system 350 in a subterranean formation 378. The well system 350 includes a wellbore 351 with a wellbore opening at surface 301. The surface 301 can be ground level for an on-shore application and the sea floor for an off-shore application. While not illustrated in FIG. 3, field equipment may be located at or above the surface 301, including but not limited to one or more of a circulation unit, a derrick, a tool pusher, a clamp, a tong, drill pipe, a drill bit, isolator subs, tubing housing, a power source, casing pipe, and a wireline tool.

[0121] In the example of FIG. 3, a surface casing 350 is deployed in the wellbore 351 along the face of the formation 378. An intermediate casing 360 is located at the surface 301. In preparation for inserting the intermediate casing 360 into the wellbore 351, a casing centralizer 370 has been attached to the outer surface of the intermediate casing 360. In the example in FIG. 3, the casing centralizer 370 is a bow spring type of centralizer that is cylindrical in shape and fits around the outer surface of the intermediate casing 360. The bow spring type of centralizer flexes to provide resilience. In other embodiments, the expandable polymer grout systems described herein can be used to secure other types of casing centralizers to casing.

[0122] FIG. 3 illustrates a deployment system 322 located at the surface 301 of the well system 350. The deployment system 322 includes a tank mixer 310 that receives the isocyanate component and the organic polyol component and combines them to form a grout. As described previously, a blowing agent as well as other additives may also be added to the tank mixer 310. A pump 312 pumps the mixture through a conduit 314 and delivers the grout 332 to a contact point 375. The contact point 375 can be a point at which the casing centralizer 370 contacts the outer surface of the intermediate casing 360. At the contact point 375, the grout 332 will expand and cure to form a bond between the casing centralizer 370 and the intermediate casing 360. The grout 332 is advantageous because its expansion will cause it to fill voids between the casing centralizer 370 and the outer surface of the intermediate casing 360. The grout 332 also is advantageous in that it can provide a strong bond that can withstand the extreme conditions often encountered in a wellbore. The grout 332 can be applied at multiple contact points between the casing centralizer 370 and the intermediate casing 360 to further secure the casing centralizer 370 to the intermediate casing 360. Once the grout bonds have been placed at one or more contact points securing the casing centralizer to the intermediate casing 360, the intermediate casing can be lowered into the wellbore 351.

[0123] Referring now to FIG. 4, another application of the expandable polymer grout systems is illustrated. Specifically, FIG. 4 illustrates using the expandable polymer grout system to mold a casing centralizer to an exterior surface of a casing. In this application, as described further below, operations are performed at the surface whereby the expandable polymer grout system is placed inside a mold to form a casing centralizer on the exterior of the casing before the casing with the casing centralizer are inserted into the wellbore. The wellbore is illustrated in FIG. 4 for context. As described previously, a casing centralizer is placed around the exterior surface of a casing joint or segment before the casing is placed into a wellbore. The casing centralizer is used to maintain the position of the casing in a wellbore relative to another surrounding casing. However, the harsh environmental conditions often encountered within a well present challenges with respect to maintaining the casing centralizer securely attached to the casing. The harsh environmental conditions can include extreme temperatures and pressures, corrosive fluids, and erosive slurries containing solids. Additionally, some centralizers deployed to location are either defective or inappropriately sized relative to the casing on site. Accordingly, the unique characteristics of the expandable polymer grout systems described herein can provide advantages with respect to securing a casing centralizer to a casing. The ability to generate centralizers on-site by injecting expandable grout into an appropriate centralizer mold on-site adds significant flexibility to the operation of casing the well in case of incorrect or defective centralizers.

[0124] In a preferred embodiment, the expandable polymer grout system is deployed at the surface of the well system and is molded into the form of a casing centralizer attached to a casing before the casing is lowered into a wellbore. FIG. 4 illustrates a well system 450 in a subterranean formation 478. The well system 450 includes a wellbore 451 with a wellbore opening at surface 401. The surface 401 can be ground level for an on-shore application and the sea floor for an off-shore application. While not illustrated in FIG. 4, field equipment may be located at or above the surface 401, including but not limited to one or more of a circulation unit, a derrick, a tool pusher, a clamp, a tong, drill pipe, a drill bit, isolator subs, tubing housing, a power source, casing pipe, and a wireline tool.

[0125] In the example of FIG. 4, a surface casing 450 is deployed in the wellbore 451 along the face of the formation 478. An intermediate casing 460 is located at the surface 401. In preparation for inserting the intermediate casing 460 into the wellbore 451, a centralizer mold 480 has been attached to the outer surface of the intermediate casing 460. In the example in FIG. 4, the centralizer mold 480 has a cylindrical shape and fits around the outer surface of the intermediate casing 460. In other embodiments, centralizer molds having other shapes can be used to form a grout centralizer on the outer surface of a casing.

[0126] FIG. 4 illustrates a deployment system 422 located at the surface 401 of the well system 450. The deployment system 422 includes a tank mixer 410 that receives the isocyanate component and the organic polyol component and combines them to form a grout. As described previously, a blowing agent as well as other additives may also be added to the tank mixer 410. As another example, a lubricant additive may be added to the mixture so that the expanded and cured grout has an enhanced lubricity to facilitate sliding along equipment in the well system. A pump 412 pumps the mixture through a conduit 414 and delivers the grout 432 into the annulus between the centralizer mold 480 and the intermediate casing 460. Once placed in the centralizer mold 480, the grout 432 expands and cures such that it becomes bonded to the outer surface of the intermediate casing 460. After the grout has cured, the centralizer mold 480 can be removed and the casing centralizer formed of the grout 432 remains bonded to the outer surface of the intermediate casing 460. With the grout-based casing centralizer attached to the intermediate casing 460, the intermediate casing 460 can now be lowered into the wellbore 451.

[0127] The casing centralizer formed of the grout 432 is advantageous in several respects. The grout 432 provides a strong bond so that the casing centralizer can withstand the extreme conditions often encountered in a wellbore. The grout 432 also has resilient characteristics that enhance its ability to receive a variety of forces but maintain its shape and position on the casing. Another benefit is that the grout 432 can have enhanced lubricity facilitating the sliding of the casing centralizer along the surface casing 450 as the intermediate casing 460 is placed into the wellbore 451.

[0128] Although embodiments described herein are made with reference to the examples illustrated in the figures, it should be appreciated by those skilled in the art that various modifications are well within the scope of this disclosure. Those skilled in the art will appreciate that the example embodiments described herein are not limited to any specifically discussed application and that the embodiments described herein are illustrative and not restrictive. From the description of the example embodiments, equivalents of the elements shown therein will suggest themselves to those skilled in the art, and ways of constructing other embodiments using the present disclosure will suggest themselves to practitioners of the art. Therefore, the scope of the example embodiments is not limited herein.