BACKGROUND OF THE INVENTION

This invention pertains generally to polychloroprene coagulates that may be used to fill gaps, voids or cavities in a time controlled manner. More specifically, the invention pertains to the controlled coagulation of polychloroprene latex with at least one of an isocyanate, an acid, a salt, or a gas, for use as a filler or sealant of distal gaps, voids, or cavities.

Many different industrial processes form gaps, voids or cavities in subterranean regions that may require filling, sealing or stabilization. For example, mining operations involve the removal of large quantities of ore-bearing rock or earth from a geological formation leaving behind voids. Likewise, the gas and oil industries also remove large quantities of rock and earth during drilling operations forming large subterranean voids which must be stabilized and later filled after operations have been completed. Further, during such mining operations or the drilling of a wellbore, incompetent or otherwise unstable subterranean zones or formations such as unconsolidated sands or shales may be encountered. Such unstable zones or formations can have very high permeabilities whereby severe drilling fluid losses occur into the zones or formations. These zones or formations are also at risk of cave in, or slough off or wash out due to the flow of drilling fluid.

In the oil and gas industry, unstable subterranean zones or formations have heretofore been enlarged and filled with cementitious material. After the cementitious material has set, the wellbore has been drilled through the cementitious material leaving a cementitious sheath in the wellbore for preventing undesired fluid influx, fluid losses, cave-ins, etc. Alternatively, the cement slurry may be pumped down the inside of a pipe or casing and back up the outside of the pipe or casing through the annular space. This seals the subterranean zones in the formation and supports the casing. Because conventional cementing slurries set quickly, they cannot be made in advance of their use. As such, large subterranean voids or unstable regions cannot be filled or stabilized all at once. This may add considerable cost and time delays to the stabilization process. Further, the cement slurries have very high viscosities and as such typically are only capable of filling 25% of a smaller gap or void, and are thus not useful for stabilization of incompetent or otherwise unstable subterranean zones. Furthermore, the cement deposited in voids is subjected to a number of stresses. For example, the pressure inside a well casing can increase or decrease as the fluid filling it changes or as additional pressure is applied to the well. Temperature changes also create stress in the cement. Prior art solutions to this problem have been to add resins or polymers to the cement. For example, U.S. Patent 5,293,938, issued Mar. 15, 1994 to Onan, et al., discloses forming a plug or seal in a wellbore using a cement material comprising a vulcanizable rubber latex. U.S. Patent 6,065,539, issued May 23, 2000 to Noik, et al., discloses a method of cementing a casing in a well drilled in the ground using a thermosetting cementing material comprising phenol-formol resin. U.S. Patent 6,196,316, issued Mar. 6, 2001 to Bosma, et al., discloses methods for carrying out well construction, repair and/or abandonment operations using a cement material comprising a vulcanizable silicone rubber. U.S. Patent 6,899, 177, issued May 31 , 2005 to Chatterji, et al., discloses methods of cementing subterranean zones using cement compositions having a hydroxyamine compressive strength enhancing additive.

The use of resins or polymers alone to stabilize subterranean regions has long been known in the art. For example, U.S. Patent 3,176,767, issued Apr. 6, 1965 to Brandt, et al., discloses the use of liquid polyester or epoxy based resins to consolidate incompetent earth formations. U.S. Patent 3,312,296, issued May 13, 1964 to Paramore, et al., discloses the use of sprayed latex to form a seal in a wellbore against fluid influx. U.S. Patent 4,042,031 , issued Aug. 16, 1977 to Knapp, et al., discloses plugging subterranean earth formations using epoxy emulsions. U.S. Patent 5,823,273, issued Oct. 20, 1998 to Ravi, et al., discloses the use of epoxy, furan or acrylamide resins to stabilize subterranean formations. U.S. Patent 5,944, 105, issued Aug. 31 , 1999 to Nguyen, discloses the use of novalac, polyepoxide, polyester, phenol-aldehyde, urea-aldehyde, furan and urethane resins to stabilize subterranean formations. U.S. Patent 6,767,867, issued Jul. 27, 2004 to Chatterji, et al.. discloses methods of treating subterranean zones penetrated by well bores using an aqueous well treating fluid comprised of water and a cationic, anionic or amphoteric polymer and hydroxyethylcellulose. U.S. Patent 7,345,01 1 , issued Mar. 18, 2008 to Nguyen, et al., disclosed the use of a furan-based resin for mitigating the production of water from a subterranean formation. U.S. Patent 8,235, 1 16, issued Aug. 7, 2012 to Burts, et al. , discloses a two part epoxy system for well remediation.

Unfortunately, curing of the non-cementious plugging agents of the prior art is frequently also accompanied by shrinkage, potentially leading to gaps or cracks in the seal and/or lack of bonding of the seal, plug or connection to its surroundings. In well bore drilling operations, this will especially occur if the adhesion of the thermosetting resin to the steel casing surface is less than the forces induced by the shrinkage process.

The prior art use of latexes to fill gaps or voids has been primarily as an additive to concrete mixtures as described above. U.S. Patent 6,802,375, issued Oct. 12, 2004 to Bosma, et al. , discloses a method for carrying out well construction, repair and abandonment using a silicone latex resin. The well-bore is cooled prior to deposition of the latex so that the coagulation may occur at a temperature lower than ambient. Once the latex is coagulated, the temperature is returned to ambient, and any shrinkage that has occurred in the latex is obviated. Such a method requires the use of additional equipment, materials and time to cool the gap or void prior to filling.

An additional problem with the use of latex materials to fill voids has been the stability of coagulated latex under high temperatures, especially the temperatures experienced in many underground regions.

It therefore remains desirable to further improve existing compositions and methods to overcome the aforementioned drawbacks.

SUMMARY OF THE INVENTION

According to its major aspects, and briefly stated, the present invention includes a latent curing polychloroprene composition and methods for coagulation of the polychloroprene composition in a controlled manner to fill distal cavities, gaps or voids. Polychloroprene may be coagulated by mixing with several different curing agents such as, for example, polyisocyanates, blocked polyisocyanates, aci15210ds, salts, certain gases, or by shear forces alone. Certain amounts and combinations of these curing agents may act in a latent manner to provide for a polychloroprene composition which may be coagulated in a time dependent manner.

Thus, the present invention relates to a latent curing composition comprising: (a) an aqueous dispersion of polychioroprene particles; and

(b) at least one curing agent,

wherein addition of the curing agent effects curing of the polychioroprene particles not sooner than one hour after addition.

In embodiments of the latent curing composition, component (a) may be an aqueous alkaline dispersion of polychioroprene particles having 25 wt. % to 60 wt. % solids and a monomer content of less than 50ppm, based on the total weight of the dispersion, in further embodiments, component (a) may be an aqueous alkaline dispersion of polychioroprene particles having 50 wt. % to 60 wt. % solids, or preferably 55 wt. % to 58 wt. % solids, based on the total weight of the dispersion. Further, component (a) may have a pH of 11 to 13, or preferably a pH of 12 to 13.

In certain embodiments of the latent curing composition, component (a) may have hydroxy I groups available for crosslinking as well as a free chloride content, arising from the elimination of chloride ions from the polychioroprene polymer, of >50ppm,≥100ppm, or≥200ppm. Component (b) may be a polyisocyanate such as a water dispersible aliphatic polyisocyanate selected from the group consisting of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI). Component (b) may also be a blocked polyisocyanate, a salt, an acid, or a gas.

In further embodiments, the latent curing composition may comprise additional materials, such as thickeners, emulsifiers, stabilizers and surfactants.

The latent curing composition may contain 20 to 99.99% by weight of said component (a), 0.01 to 10% by weight of said component (b), 0.01 to 79.99% by weight of other additives and water, wherein the percentages by weight relate to the solids content of the composition, which adds up to 100%.

The present invention also relates to a method of filling a distal cavity, gap or void in a subterranean region. The method comprises providing a polychioroprene component (a) and a curing component (b); surface mixing said components (a) and (b) to form a liquid blend; placing said liquid blend in the distal cavity, gap or void; and allowing said liquid blend to coagulate and form a solid. Component (a) may be an aqueous alkaline dispersion of polychioroprene particles having 25 wt. % to 60 wt. % solids, based on the total weight of the dispersion, and a pH of between 11 and 13, while component (b) may be selected from the group consisting of a hydrophilized polyisocyanate, a blocked polyisocyanate, a salt, an acid, or a gas. In certain embodiments, the liquid blend may further comprise additional materials selected from the group consisting of thickeners, emulsifiers, stabilizers, and surfactants.

The present invention further relates to a method for filling a remote gap or void, the method comprising (i) pumping a latent curing composition consisting essentially of a mixture of an aqueous alkaline dispersion of polychloroprene particles and at least one curing agent into a remote gap or void in a subterranean region, and (ii) allowing the latent curing composition to form a coagulated solid, wherein the remote gap or void is greater than 50% filled by the coagulated latent curing composition. In certain embodiments, the gap or void may be greater than 75% or 90% filled by the coagulated latent curing composition. The at least one curing agent may be selected from the group consisting of a hydrophilized polyisocyanate, a blocked polyisocyanate, a salt, an acid, or a gas. In certain embodiments, the latent curing composition may further comprise additional materials selected from the group consisting of thickeners, emulsifiers, stabilizers, and surfactants.

DETAILED DESCRIPTION OF THE PREFERRED EiVSBODiiVSENTS

For purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements. Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

In this application, the use of the singular includes the plural and plural encompasses singular, unless specifically stated otherwise. In addition, in this application, the use of "or" means "and/or ^* unless specifically stated otherwise, even though "and/or" may be explicitly used in certain instances.

In the following description, the present invention is set forth in the context of various alternative embodiments and implementations involving the coagulation of polychloroprene in a controlled manner to fill distal voids. As used in this description and the appended claims, the term "void" includes all forms of cavities, pits, gaps, openings and the like, whether above or below ground, and whether a man-made or natural formation.

Polychloroprene may be coagulated by mixing with several different curing agents such as, for example, acids, salts, or certain gases, or by shear forces alone. Further, exposed hydroxyl groups on the polychloroprene may be crosslinked by polyisocyanates to form urethane linkages or may form ester linkages through transesterification. Certain amounts and combinations of these curing agents may act in a latent manner to provide a polychloroprene composition which may be coagulated in a time dependent manner.

Thus, the present invention relates to a latent curing composition comprising (a) an aqueous alkaline dispersion of polychloroprene particles and (b) at least one curing agent, wherein addition of said curing agent effects curing of the polychloroprene particles not sooner than one hour after addition. The term "polychloroprene particles", according to the invention, may be understood to be particles of polychloroprene (poly(2-chloro-1 ,3-butadiene) and chloroprene-containing copolymers.

Component (a) is preferably used in the form of a 25 to 60 wt. %, based on total dispersion weight, of aqueous alkaline polymer dispersion of polychloroprene particles with a pH of 8-13. Preferably, component (a) is used in the form of a 50 to 60 wt. %, based on total dispersion weight, of aqueous alkaline polymer dispersion of polychloroprene particles with a pH of 11-13. Also preferable as component (a) are 55 to 58 wt. %, based on total dispersion weight, of aqueous alkaline polymer dispersions of polychloroprene particles with a pH of 12-13.

In certain embodiments of the present invention the aqueous dispersion of polychloroprene particles may have a measurable chloride content arising from the elimination of chloride ions from the polychloroprene. The elimination of the chloride ions from the polychloroprene polymer may be effected in the conventional manner by storing the aqueous alkaline polymer dispersion at room temperature, or accelerated by a heat treatment, preferably at

temperatures of 40 to 90°C. In certain embodiments of the present invention, the chloride content may be at least 50ppm. Storage of the aqueous dispersion of polychloroprene particles which leads to elimination of chloride ions from the polychloroprene may also lead to a reduction of the alkalinity of the dispersion. The pH of the dispersions may be stabilized by the addition of certain acids, buffers or stabilizing agents as listed below.

The pH of the aqueous alkaline polymer dispersion of polychloroprene particles results from appropriate contents of alkali metal hydroxide and/or alkali soaps, which may be required for the chemical, microbial or colloidochemical stabilization of the polymer dispersions.

The aqueous alkaline polymer dispersion of polychloroprene particles to be used according to the present invention as component (a) can be prepared in the conventional manner, e g. by the emulsion polymerization of 2-chlorobuta-1 ,3-diene as described in Ullmann's Encyclopedia of Industrial Chemistry (Obrecht, W ef. a/., 2011. Rubber, 4. Emulsion Rubbers). Of course, it is also possible to use copolymers of 2-chlorobuta-1 ,3-diene with other olefinically unsaturated monomers, e.g. 2,3-dichlorobutadiene or methacrylic acid, as component (a). Such copolymers are also known and are described for example in the reference cited above. Emulsion polymerization of chloroprene and optionally an ethyienically unsaturated monomer copolymerizable with chloroprene in an alkaline medium is also described, for example, in WO-A 02/24825 (p. 3, line 26-p. 7, line 4), DE-A 30 02 734 (p. 8, line 23-p. 12, line 9), and U.S. Patent 5,773,544 (cf. the section from line 9 in column 2 to line 45 in column 4). More preferred polychloroprene dispersions are those prepared _Q

-8- by continuous polymerization, as described, for example, in WO-A 02/24825, Example 2 and DE 3 002 734, Example 6.

Emulsifiers in principle may be any compounds or mixtures thereof that stabilize the emulsion sufficiently such as, for example, the water-soluble salts, in particular the sodium, potassium and ammonium salts of long-chained fatty acids, colophony and colophony derivatives, higher molecular weight alcohol sulfates, arylsulfonic acids or formaldehyde condensation

products of arylsulfonic acids. Co-em ulsifiers which may be mentioned by way of example include non-ionic emulsifiers based on polyethylene oxide and polypropylene oxide, as well as polymers having an emulsifying action, such as polyvinyl alcohol.

Typically, the polychloroprene may be stabilized during the polymerization stage of the process through the use of anionic surfactants. Such anionic surfactants can be selected from the group of alkali and alkaline earth salts of fatty acids such as oleates, palmitates, stea rates, abietates, and mixtures thereof. Also, alkyl and alkaryl sulfonates, sulfosuccinates, sulfated or sulfonated esters and ethers, sulfated or sulfonated amines and amides may be utilized. Any anionic surfactant can be used that has water solubility and a surface activity sufficient to emulsify the reaction mixture.

Polychloroprenes which are suitable according to the present invention can be prepared in an alkaline emulsion, at temperatures of from 0 to 70°C, in the presence of from 0 to 20 parts by weight, based on 100 parts by weight of chloroprene, of copolymerisable ethylenically unsaturated monomers in the presence of from 0 to 1 mmol of a regulator, based on 100 g of monomer. Xanthogen disulphides and preferably mercaptans may be used as regulators.

The aqueous alkaline polymer dispersion of polychloroprene particles to be used according to the present invention as component (a) may have a low residual monomers content. Not only are residual monomers potentially toxic to the environment, they may have undesirable effects on the odor and physical properties of the coagulated polychloroprene. As such, in certain embodiments of the latent curing composition of the present invention, the monomer content of the polychloroprene dispersions suitable as component (a) may have a monomer content of less than 50ppm. Preferred polychloroprene dispersions useful as component (a) according to the present invention are the Dispercoll® C series of polychloroprene latexes (Bayer Materia ISciences LLC).

Component (b) of the latent curing composition of the present invention is a curing agent. Suitable as component (b) are hydrophilized polyisocyanates based on preferably aliphatic isocyanates, for example l-isocyanato-3,5,5- trimethyl-5-isocyanatomethyl-cyclohexane (I PDI) or 1 ,6-diisocyanatohexane (HDI). Suitable for this purpose are, for example, water-dispersible polyisocyanate preparations of an aliphatic polyisocyanate and a reaction product of an aliphatic polyisocyanate with a mono- or di-hydric, non-ionic polyalkylene ether alcohol as emulsifier, for example based on isocyanurates and biurets and a!lophanates based on HDI and/or isocyanurates based on IPDI. Correspondingly modified polyisocyanate mixtures are likewise suitable. Also suitable are polyisocyanates or polyisocyanate mixtures having an isocyanurate structure based on HDI, IPDI and/or 4,4'-diisocyanatodicyclohexylmethane. Suitable non-ionic emulsifiers are also polyisocyanates modified by polyvinylpyrrolidone. As dispersing-active constituents there are also used polyalkylene oxide ethers containing carboxyiic acid groups, or polyether ester alcohols.

Preferred polyisocyanates useful as component (b) according to the present invention are the Bayhydur® series of water dispersible polyisocyanates (Bayer MaterialSciences LLC).

Also suitable as component (b) of the latent curing composition of the present invention are blocked polyisocyanates. When heated, the blocked polyisocyanates may release their blocking groups to react with hydroxyl functionalities. As such, blocked polyisocyanates provide a convenient means to initial coagulation of the latent curing composition upon exposure to elevated temperatures. Such temperatures may depend on the polyisocyanate and blocking agent selected and are well known to those of skill in the art.

Suitable polyisocyanates which may be used in a blocked form are, for example, aliphatic, cycloaliphatic, aromatic and heterocyclic polyisocyanates such as ethylene diisocyanate; tetramethylene diisocyanate; hexamethylene diisocyanate; dodecamethylene diisocyanate; cyclobutane-1 ,3-diisocyanate; cyclohexane-1 ,3- and -1 ,4-diisocyanate and any mixtures of these isomers; IPDI; hexahydrotolylene-2,4- and -2,6-diisocyanate and any mixtures of these isomers; hexahydropheny!ene-1 ,3- and/or 1 ,4-diisocyanate, phenyiene-1 ,3- and -1 ,4- diisocyanate; tolylene-2,4- and -2,6-diisocyanate and any mixtures of these isomers; diphenylmethane-2,4'- and/or -4,4'-diisocyanate; naphthylene-1 ,5-diisocyanate; triphenylmethane-4,4',4"-triisocyanate; polyphenylpolymethylene polyisocyanates which can be obtained by aniline-formaldehyde condensation followed by phosgenation; perchlorinated aryl polyisocyanates; polyisocyanates which contain carbodiimide groups; diisocyanates of the kind described in U.S. Patent 3,492,330; polyisocyanates which contain allophanate, isocyanurate, urethane, acylated urea, ester or biuret groups; polyisocyanates prepared by telomerization reactions; and reaction products of the above mentioned isocyanates with acetylene.

Polyisocyanates which are particularly advantageous to use in their blocked form are 2,4-diisocyanatotoluene; 2,6-diisocyanatotoluene: commercial mixtures of these isomers; 4,4'-diisocyanatodiphenylmethane; 4,4'-diisocyanatodiphenyl- dimethylmethane; 1 ,5-diisocyanatonaphthalene; mixtures of homologues or isomers of the kind which can be obtained in known manner by phosgenation of aniline/formaldehyde condensates; the triisocyanate containing urethane groups which can be obtained in known manner by reacting 3 mofs of 2,4- diisocyanatotoluene with 1 mol of trimethylolpropane, and the isocyanato- isocyanurate which can be obtained in known manner by trimerizing 2,4- diisocyanatotoluene.

When isocyanates are used as the curing agent of component (b), the aqueous dispersion of polychloroprene particles according to the present invention may contain a certain proportion of OH groups which are crosslinkable with isocyanate. Such OH groups may be obtained by the elimination of chloride ions from the polychloroprene polymer. This considerably increases the crosslinkability of the polychloroprene polymers with the isocyanates. The elimination of the chloride ions from the polychloroprene polymer may be effected in the conventional manner by storing the aqueous alkaline polymer dispersion at room temperature, or accelerated by a heat treatment, preferably at temperatures of 40 to 90°C.

Also suitable as component (b) of the latent curing composition of the present invention are activators, such as, for example, monovalent, divalent or trivalent inorganic salts, for example KCi, NaCI, NaaSO.*, ZnC , gC , CaC , AlCh, ^

Al2(S04)3, or inorganic or organic acids, for example HQ, boric acid, phosphoric acid, as well as acetic acid, glycine or other suitable amino acids, tartaric acid, citric acid, or their alkali and alkaline earth salts, as well as arbitrary combinations of salts and acids, such as buffer systems, for example the simple sodium or potassium salt of phosphoric acid (KH2PO4), NaHCCh or KHCO3. Further, these may be used to pre- activate the aqueous polymer dispersions in order to establish a particular initial pH value.

The pH value may be adjusted in any convenient manner by introducing into the aqueous alkaline dispersion of polychloroprene particles any suitable acid. Weak or strong organic or inorganic acids may be used, including chemical compounds which generate an acid in situ, for example, carbon dioxide. The acid or acid generating compound may be added alone or in combination with another curing agent. Suitable acids include, among others, hydrochloric, sulfuric, nitric, phosphoric, benzenesulfonic, hydrofluoric, hydroiodic, trifluoroacetic, and trichloroacetic acids.

Also suitable as component (b) of the latent curing composition of the present invention is carbon dioxide. Carbon dioxide may be used as a weak acid for neutralizing anionica!ly stabilized polymer dispersions, with the aim of direct coagulation in order to obtain a solid from the dispersion. As such, carbon dioxide in an amount, per liter of formulation, of from 0.1 to 20 liters, preferably from 0.2 to 10 liters, particularly preferably from 0 5 to 5 liters, most particularly preferably from 0.8 to 3 liters, is fed at from 1 to 100°C and from 0.8 to 10 bar to an aqueous polymer dispersion containing an anionically stabilized polychloroprene dispersion.

The carbon dioxide volumes can be supplied, for example, by over-layering of the dispersion inside a resilient vessel. For example, a vessel having a volume of 20 liters can be filled with X<18 liters of dispersion (optionally with the exclusion of air) and then filled up with 20-X liters of carbon dioxide. After shaking or stirring or storing the vessel until the desired reduction in volume of the carbon dioxide gas phase has been achieved by absorption into the dispersion, the aqueous polymer dispersion is activated. Any excess carbon dioxide is released.

Further, the supply of carbon dioxide may be effected, for example, by introduction, passing through, passing over or over-layering, by means of static or dynamic mixers, inside mixing pipes, also in the form of carrier gas or propellant gas. The carbon dioxide sources used are, for example, compressed-gas containers, such as bottles, cartouches or cartridges, chemical reactions of, for example, alkali carbonates with suitable acids in situ, liquids saturated with carbon dioxide (e.g. water, mineral water, soft drinks) or carbon dioxide obtained from the sublimation of dry ice or a reversible carbon dioxide absorber. Preference is given to mechanically contactless methods such as passing over or over-layering, where the formulation to be activated does not come into contact with the metering unit. Contamination or blocking of the metering unit by the possible formation of coagulate is thus avoided.

Preference is likewise given to the use of carbon dioxide directly as a carrier gas or propellant gas for the application, for example in the form of spray cans containing the formulation and carbon dioxide in separate phases or the mixing of the polymer dispersion and carbon dioxide in a defined flow region, for example by means of a static mixer or simple hose section of suitable length prior to application. Preference is given to the metered addition of carbon dioxide from a pressure cylinder, cartouche or cartridge by means of simple mobile valve systems analogous to bicycle and motor vehicle tire valves, it being possible for the valve system to be mounted reversibly, for example, on the adhesive formulation packaging. After the introduction of the desired amount of carbon dioxide, the original cap can be replaced if required and the container can be shaken, stirred and stored until the formulation is saturated with the added carbon dioxide. In the case of flexible containers, the progress of the activation can easily be monitored by the reduction in volume of the vessel.

Polychloroprene coagulates may be formed by applying shear forces to the aqueous dispersions of component (a), in embodiments of the latent curing composition of the present invention, agitation may be used to create such a shear force and may be applied by any mechanical means known in the art such as, for example, by a mixer, agitator, or shaker, or by non-mechanical means such as, for example, by passage through a spay nozzle. In certain further embodiments, mechanical or non-mechanical agitation may be applied to the latent curing composition of the present invention just prior to deposition in the void. This final step may act to rapidly coagulate the polychloroprene of component (a).

Further, mixtures of additives which may aid in the coagulation of the polychloroprene when placed under shear force by agitation are within the scope of the present invention. For example, the latent curing composition may be passed to a shear coagulator where a water soluble cationic surfactant containing a quaternary ammonium or other cationic salt is added. Quaternary ammonium salts are well known and include alkyl and aryl ammonium halides and acetates. Cationic surfactants believed to be useful in the practice of the present invention include positively charged nitrogen containing compounds having at least one hydrophobic R group, usually derived from either fatty acids or petrochemical sources. The R group may be attached directly to the nitrogen as in the case of stearyl trim ethyl ammonium chloride, or indirectly as in the case of diisobutyl phenoxyethoxy ethyl dimethylbenzyl ammonium chloride. The nitrogen atom can also be a part of a heterocyclic ring as in the case of alkyl pyridinium salts or alkyl imidazolinium salts.

The combination of the shear force generated by the shear coagulator and the addition of the cationic surfactant may cause the polychloroprene to coagulate. Even where the polychloroprene of component (a) has previously been stabilized against coagulation by the use of anionic soaps, the process of the present invention may be effective. While a stoichiometric equivalent amount of a cationic surfactant such as a quaternary ammonium salt may be used to neutralize the anionic soap, it may also be effective to cause coagulation at much lower levels of cationic surfactant, such as from about 1 to about 50%, and preferably from about 10 to about 25%.

The latent curing composition according to the present invention may include mixtures or combinations of the above mentioned curing agents suitable as component (b). For example, carbon dioxide or another acid may be added as component (b) to lower the pH of the aqueous dispersion of polychloroprene particles used as component (a), and thus destabilize the polychloroprene. Shear forces may then be applied to the latent curing composition by mechanical or non-mechanical agitation at the time of deposition into a void thus initiating coagulation of the polychloroprene dispersion. Such shear forces may be applied, for example, by forcing the composition to exit a nozzle at high pressure or speed. Further, a carrier gas such as described above may be added to the composition just prior to deposition into the void. As an example, the pH destabilized latent curing composition may be deposited to the void from the end of a spray nozzle where carbon dioxide is used as a carrier gas.

The latent curing composition according to the present invention may also contain auxiliary substances. These include, for example, defoamers, ionic or ^ nonionic surfactants, fillers and wetting agents. Fillers may include quartz powder, highly disperse silicic acid, calcium carbonate, chalk, dolomite or talcum, which are often used together with wetting agents such as naphthalenesulphonic acid salts, the wetting agents generally being added in amounts of 0.2 to 0.6 wt. %, based on the filler used.

The latent curing composition according to the present invention may also contain stabilizers such as divalent, predispersed metal oxides (ZnO, MgO, CaO), in some cases present as nanoparticles, and/or aminic acid acceptors (e.g. described in WO-A 2004/106422). Stabilizers useful as anti-aging additives in the present invention may include sterically hindered phenol derivatives, amines, phosphites, xanthogene disulfides or thiuram disulfides, all of which may be used to improve the stability of the polymers in storage.

Preferable anti-aging additives may be based on oligofunctional secondary aromatic amines and/or oligofunctional substituted phenols, such as products of the type 6-PPD, DTPD, DDA, BPH, BHT, etc., as described for example in Handbuch fur die Gummiindustrie, 1992 edition, Bayer AG, Leverkusen, chapter 4: Vulkanox®, p. 423. Vulkanox® DDA, a diphenylamine derivative, is particularly effective.

The anti-aging additive may be added to the polychloroprene dispersion in the form of an aqueous dispersion, organic solution or aqueous emulsion of an organic solution before or after removal of unreacted monomers.

Other suitable auxiliary substances are organic thickeners such as cellulose derivatives, alginates, starch or starch derivatives or polyacrylic acid, to be used e.g. in amounts of 0 01 to 1 wt. %, based on the total polymer dispersion, or inorganic thickeners such as barite or bentonites, to be used in amounts of 0.05 to 5 wt. %, based on the total polymer dispersion.

The latent curing composition of the present invention may contain 20 to 99.99% by weight of component (a), 0.01 to 10% by weight of component (b), 0.01 to 79.99% by weight of other additives and water, wherein the percentages by weight relate to the solids content of the composition, which adds up to 100%.

The latent curing composition of the present invention may be used to fill distal or remote voids Curing agents may be used to initiate coagulation of the polychloroprene in a latent manner such that the latent curing composition does not _{1 g} begin immediate coagulation, but rather coagulates to form a solid at a delayed time, preferably after the composition has been deposited into the remote void. Certain combinations of curing agents may initiate coagulation of the polychloroprene in component (a) at specific times and temperatures. As such, the distance or time to fill the distal or remote void and the temperature of the remote void may determine the selection and amount of the curing agent(s). Further, the method to fill the distal or remote void may determine the selection and amount of the curing agent(s).

Thus, an embodiment of the present invention is a method of filling a distal cavity, gap or void in a subterranean region. The method comprises providing a polychloroprene component (a) and a curing component (b); surface mixing said components (a) and (b) to form a liquid blend; placing said liquid blend in the distal cavity, gap or void; and allowing said liquid blend to coagulate and form a solid. Component (a) may be an aqueous alkaline dispersion of polychloroprene particles having 25 wt. % to 60 wt. % solids and a pH of between 11 and 13, while component (b) may be selected from the group consisting of a hydrophilized polyisocyanate, a blocked polyisocyanate, a salt, an acid, or a gas. In certain embodiments, the liquid blend may further comprise additional materials selected from the group consisting of thickeners, emulsifiers, stabilizers, and surfactants.

A further embodiment of the present invention is a method for filling a remote gap or void, the method comprising (i) pumping a latent curing composition consisting essentially of a mixture of an aqueous alkaline dispersion of polychloroprene particles and at least one curing agent into a remote gap or void in a subterranean region, and (ii) allowing the latent curing composition to form a coagulated solid, wherein the remote gap or void is greater than 50% filled by the coagulated latent curing composition. The at least one curing agent may be selected from the group consisting of a hydrophilized polyisocyanate, a blocked polyisocyanate, a salt, an acid, or a gas. In certain embodiments, the latent curing composition may further comprise additional materials selected from the group consisting of thickeners, emulsifiers, stabilizers, and surfactants.

The methods of the present invention allow for more complete filling of remote voids and thus may provide for more complete geo-stabilization and/or for a better seal in subterranean regions. This is due, in part, to the use of a composition having low viscosity which may effectively fill a greater proportion of any subterranean region than the prior art compositions. For example, the aqueous alkaline dispersions of polychloroprene particles used herein typically have viscosities (DIN 53019) of 100 cps/mPa s or less (see TABLE 1 ). As such, remote gaps or voids may be greater than 50% filled by the coagulated latent curing composition. In preferred embodiments of the present invention, the compositions of the present invention may enable filling of remote gaps or voids to a level of greater than 75%, or even greater than 95%.

Further, the curing agents or combination of curing agents of the present invention may allow for a broader range of coagulation times for the polychloroprene under a broader range of temperatures. For example, drilling operations often necessitate the filling of gaps or voids under elevated temperatures such as, for example, temperatures approaching 70°C. In fact, temperatures at wellbores have been observed as high as 150°C. The latent curing compositions of the present invention may be formulated to coagulate at a specific time interval at such high temperatures, and to remain stable (solid) with continued exposure to the increased temperatures.

Another advantage of the compositions and methods of the present invention is the coagulation or curing time of the polychloroprene dispersions. Compositions of the prior art using cement would begin to set quickly, making it hard to pump the material over long distances into remote gaps or voids. The cement would then not become fully cured for days to weeks. As such, the full geo-stabilization provided by such mixtures would not be evident for long periods of time. During the drilling of a wellbore, such delays add to the costs of production. The latent curing compositions of the present invention eliminate such drawbacks. Once the polychloroprene dispersion starts to coagulate, the process is rapid, typically occurring in a matter of minutes.

Further, it has been found that the addition of certain surface active agents such as, for example, thickeners and surfactants, may delay the coagulation of the polychloroprene dispersion of the present invention when exposed to certain external contaminants, such as the salts present in salt water. Thus, the latent curing composition of the present invention offers a broader range of curing times across a broader range of environmental conditions that the prior art compositions.

The compositions and processes of the present invention may also be used to improve the repair of buildings, foundations, roads, bridges, highways, sidewalks, tunnels, manholes, sewers, sewage treatment systems, water treatment systems, reservoirs, canals, irrigation ditches, etc.; and in the geo-stabilization of mines, caves, wells, bore-holes, ditches, trenches, pits, cracks, fissures, craters, pestholes, potholes, sinkholes, wallows, waterho!es and the like.

_{1 Q}

EXAMPLES

The instant process is illustrated, but in no way restricted, by the following examples in which quantities quoted represent parts by weight or percentages by weight, unless otherwise stated.

Materials used in the examples.

TABLE 2

Example 1 - Testing of coagulation times for various mix ratios of polychloroprene component (a) and polyisocyanate component (b).

Varying ratios of component (a) as listed in TABLE 1 and component (b) as listed in TABLE 2 were combined and mixed for 1 minute at 400rpm. All samples showed a coagulated skin on the surface within 1 hour but the samples did not start to thicken until 2 hours. Times to final cure are shown in TABLE 3 and TABLE 4. Once cured, the compositions containing 9 parts component (b) were dense enough to run a drill through.

TABLE 3

TABLE 4

Example 2 - Testing of the pH stability of component (a) containing hydroxy I groups.

The pH stability of various Dispercoll® C dispersions (see TABLE 1) was measured upon storage at 60°C. Dispercoll® C 2325 is a dispersion that has been "pre-aged" to form an increased content of hydroxyl groups, after which the formulation has been pH adjusted to an alkaline pH of 12.5. As can be seen in TABLE 5, the pre-aged dispersion is more pH stable during storage at eievated temperatures.

TABLE 5

Example 3 - Testing of the heat resistance for latent curing compositions containing polychloroprene component (a) and various polyisocyanate component (b).

TABLE 6

Crosslinking with various isocyanates showed an improvement in the heat resistance with of the coagulated polychloroprene dispersions (TABLE 6).

Example 4 - Testing of the mix ratios for latent curing compositions containing various polychloroprene component (a) and carbon dioxide component (b). - -

TABLE 7

The stability of various polychioroprene dispersions upon carbon dioxide addition was tested (TABLE 7). The pH value was measured using a single-rod 5 measuring electrode (e.g. Sentron pH meter) immersed in the dispersion or solution to be tested. This contains a measuring electrode and a reference electrode. The potential difference between the measuring electrode and the reference electrode is read off on the measuring device as the pH value. The manufacturer's operating instructions are to be followed for

handling of the single-rod measuring electrode. Alternatively, the pH value can be determined by means of measuring rods or initiator paper or by means of indicator solution.

It will be appreciated that the aforementioned embodiments and implementations are illustrative and various aspects of the invention may have applicability beyond the specifically described contexts. Furthermore, it is to be understood that these embodiments and implementations are not limited to the particular components, methodologies, or protocols described, as these may vary. The terminology used in the description is for the purpose of illustrating the particular versions or embodiments only, and is not intended to limit their scope in the present disclosure which will be limited only by the appended claims.