MX2008008506A - Cement compositions comprising particulate carboxylated elastomers and associated methods - Google Patents

Abstract

Methods of cementing comprising:providing a cement composition comprising water, a cement, and a particulate elastomer comprising a carboxy group;and allowing the cement composition to set. Cement compositions comprising water, a cement, and a particulate elastomer comprising a carboxy group.

Description

CEMENT COMPOSITIONS COMPRISING CARBOXYLATE ELASTOMERS IN PARTICLES AND ASSOCIATED METHODS FIELD OF THE INVENTION The present invention relates to cementing operations and, more particularly, to cement compositions comprising particulate carboxylated elastomers and associated methods. BACKGROUND OF THE INVENTION Cement compositions are commonly used on soils (for example, in the construction industry) and in underground works, particularly for remediation works and completion of underground wells. For example, cement compositions are used primarily in primary cementing operations by means of which pipe columns such as casing tubes and casing pipes are cemented in drill holes. In performing a preliminary cementation, the cement compositions are pumped into the annular space between the walls of a drilling well and the outer surface of the pipe column there disposed. The cement composition is allowed to be placed in the annular space, thereby forming an annular cover of substantially hardened impermeable cement which substantially supports and locates the pipe columns in the drilling well and joins the outer surface of the pipe column to the drilling well walls. Cement compositions are also used in cementing works for remediation such as highly permeable clogging zones or fractures in drilling wells, clogging cracks and perforations in pipe columns and the like. Once placed, the cement cover can undergo a variety of cyclic stresses, cutting, tension, impact, bending and / or compression forces that can lead to the failure of the cement cover, resulting, for example, in fractures, cracks, and / or detach from the concrete cover of the pipe columns and / or the formation. This can lead to undesirable consequences such as loss of production, environmental pollution, risky equipment operations that are the product of an unexpected flow of fluids caused by loss of insulation in the area, and / or production operations with risk. Cement failures can be particularly problematic in high temperature wells, where fluids injected into wells or produced from wells by digging wells can cause the temperature of various fluids trapped within the ring to increase. In addition, the high pressure of fluids and / or temperatures within the pipe column can cause additional problems during testing, drilling, fluid injection, and / or fluid production. If the pressure and / or temperature within the pipe column increases, the pipe column can expand and tighten the surrounding cement deck. This can cause the concrete cover to crack, or the bond between the outer surface of the pipe column and the cement cover fail, thus breaking the hydraulic seal between the two. As used herein, the term "bonding" encompasses the adhesion between the surfaces, for example, between the cement cover and the pipe column, on a macroscopic scale and / or attractive forces between the portions of molecules at a level molecular, for example, between cement particles and elastomers, which can be ionic, covalent, or weak Van der Waals, dipole-dipole types, or any combination of such attractive forces. In addition, high temperature differentials created during the production or injection of high temperature fluids through the drill hole can cause fluids trapped in the cement jacket to thermally expand, causing high pressures within the shell itself. Additionally, sudden changes in temperatures and / or pressures within the drilling wells due to the change in fluid densities and temperatures possibly encountered during well drilling works (eg, construction, remediation works, fluid injection) subject the cement roof to cyclical pressures and temperatures, which if not properly designed, the cement roof may fail due to its natural brittleness properties. In addition, the failure of the cement roof can also be caused by forces exerted by the displacements in the underground formations surrounding the drill hole, wear or erosion of the cement, and repeated impacts of small perforations and drilling of the pipe. To counteract these problems, various additives can be included in the cement composition to allow the cement composition to resist cyclic changes in the imposed stresses. For example, hydrocarbon-based elastomers (e.g., styrene-butadiene random block and copolymer elastomers, acrylonitrile-butadiene elastomers, and acrylonitrile-styrene-butadiene elastomers) have been included in the cement compositions to modify the properties Mechanics of cement composition. Generally, such materials are used in the form of particles. As used herein, the term "particles" refers to materials in the solid state having a well-defined physical form as well as those with irregular geometries, including any of the particulate elastomers having the physical form of platelets, chips , fibers, flakes, ribbons, rods, strips, spheroids, hollow beads, toroids, pellets, tablets, or any other physical form. The particulate elastomers can function to control shrinkage cracking in the early phases of the cement settlement process, and can also provide resilience, ductility, and hardness to the cement composition established to resist cracking or fracture. In addition, if fracture or cracking occurs, the particulate elastomers can function to maintain the fixed cement composition, thus resisting the recoil of the cement cover. The elastomers of particulate materials can also dissipate stresses more effectively than the cement matrix, potentially shielding the cement composition from failure due to the catastrophic development of bills and cracks. However, the use of particulate elastomers in cement compositions can be problematic. The normally used particulate elastomers generally contain monomers (such as styrene, butadiene, ethylene, or propylene) that are highly hydrophobic and non-polar. As a result, conventional particulate elastomers are generally non-polar and hydrophobic, while the cement matrix is generally polar and hydrophilic. Due to the hydrophobic nature of elastomers in conventional particles, these do not generally adhere or bind to the cement matrix. Accordingly, the resulting cured cement may have a polar and hydrophilic cement matrix with the elastomers in hydrophobic and unbonded particles there dispersed. The presence of these elastomers in unbonded particles in the cement matrix generally does not allow for efficient transfer of stresses from the cement matrix to the elastomers in dispersed particles therein. Additionally, the adhesion of the cement composition to the tubing and / or surface formation may also be compromised due to the poor adhesion of hydrophobic materials to the metal and / or forming surfaces, resulting in the detachment of such surfaces, creating channels for the flow of unwanted fluids. In addition, the addition of such hydrophobic elastomers, which typically have densities either close to or less than water, to the cement slurries cause them to float in the slurry or otherwise to separate from the cement solids. The addition of hydrophobic elastomers to the water mixture prior to the addition of cement can cause the elastomer to float in the water mixture in such a way that the distribution of the elastomers in the cement slurry becomes problematic. Aqueous latex emulsions of elastomeric polymeric materials typically contain small amounts of carboxylic acid-containing monomers. For example, aqueous butadiene styrene latex emulsions typically contain small amounts of carboxylic acid-containing monomers during the polymerization of styrene and butadiene to provide stability to the aqueous emulsion. However, such latex emulsions can be problematic, in that they tend to gel the cement compositions and may require large amounts of surfactants to stabilize the latex mixtures in the cement against the premature gelling of the cement slurries. Additional problems with the use of latex emulsions in cement compositions include their general lack of stability to the presence of salts and the tendency to gel the cement compositions at elevated temperatures. In addition, aqueous latex emulsions are designed to be polymer compositions that form a film when the water is removed, for example, when the water in the cement slurry is consumed during the hydration reactions of the cement. It is not expected that such film-forming polymer compositions will be effective as stress absorbers in cement compositions relative to particulate elastomers that retain their particle nature even under well-digging conditions. Even when a particulate elastomer softens or melts under well-digging conditions, it generally remains as a localized softened elastomer or as liquid droplets in the cement matrix instead of forming a film on the hydrated cement particles, so which can generally serve as mitigating sites of efforts. SUMMARY OF THE INVENTION The present invention relates to cementing operations and, more particularly, to cement compositions comprising particulate carboxylated elastomers and associated methods. As used herein, a "carboxylated elastomer" refers to an elastomer comprising a carboxy group. One embodiment of the present invention provides a cement composition comprising water, a cement, and a particulate elastomer comprising a carboxy group. Another embodiment of the present invention provides a cement composition comprising water, a cement, a particulate elastomer comprising a carboxy group, and a particulate hydrophobic elastomer.

Another embodiment of the present invention provides a cementing method comprising: providing a cement composition comprising water, a cement, and a particulate elastomer comprising a carboxy group; and allow the cement composition to set. Another embodiment of the present invention provides a cementing method comprising: providing a cement composition comprising water, a cement, and a particulate elastomer comprising a carboxy group; introduce the cement composition in an underground formation; and allow the cement composition to set there. Another embodiment of the present invention provides a method for increasing the mechanical properties and elasticity of a cement composition, comprising: including a particulate elastomer comprising a carboxy group in the cement composition such that the cement composition comprises water , a cement, and the particulate elastomer; introduce the cement composition in an underground formation; and allow the cement composition to set there. Another embodiment of the present invention provides a method for increasing the adhesion between a cement composition and a pipe column and / or an underground formation comprising: including a particulate elastomer comprising a carboxy group in the cement composition in such a way that the cement composition comprises water, a cement, and the particulate elastomer; introduce the cement composition in the underground formation; and allow the cement composition to set there. The features and advantages of the present invention will be apparent to those skilled in the art. Although many changes can be made by those skilled in the art, such changes are within the spirit of the invention. BRIEF DESCRIPTION OF THE FIGURES These drawings illustrate certain aspects of some of the embodiments of the present invention and should not be used to limit or define the invention. Figure 1 is a schematic illustration of the arrest of stresses due to a particulate carboxylated elastomer according to an embodiment of the present invention. Figure 2 is a graphic illustration of a segment of a carboxylated elastomer comprising an elastomer and graft carboxy groups, according to one embodiment of the present invention. Figure 3 is a graphic illustration of a segment of a carboxylated elastomer having a core wrap morphology, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to operations with cement and, more particularly, to cement compositions comprising particulate carboxylated elastomers and associated methods. Although the compositions and methods of the present invention are useful in a variety of underground cementation operations and surfaces, they are particularly useful in the preliminary cementation, for example, cementation of casing tubes and casing tubes in drilling wells, which include those in multilateral underground wells. The cement compositions of the present invention generally comprise water, a cement, and a carboxylated particulate elastomer. Typically, the cement compositions of the present invention may have a density in the range of about 0.48 kg / l (4 pounds per gallon "ppg") to about 2.4 kg / l (20 ppg). • In certain embodiments, the compositions of cement may have a density in the range of about 0.96 kg / l (8 ppg) to about 2.04 kg / l (17 ppg). The cement compositions may be foamed or non-foaming or may comprise other means for reducing their densities, such as hollow microspheres, low density elastic beads, or other density-reducing additives known in the art. Those skilled in the art, with the benefit of this description, will recognize the proper density of the cement composition for a particular application. The water used in the cement compositions of the present invention may be fresh water, salt water (for example, water containing one or more salts dissolved there), brine (for example, saturated salt water produced from underground formations), water from sea, or combinations thereof. Generally, water can be from any source, as long as it does not contain an excess of compounds that adversely affect other components in the cement composition. The water may be present in an amount sufficient to form a pumpable slurry. More particularly, water may be present in the cement compositions of the present invention in an amount in the range of about 24% to about 200% by weight of cement ("epdc"). In some embodiments, water may be present in an amount in the range of about 35% to about 90% epdc. Any cement suitable for use in underground cement works can be used in accordance with the present invention. Suitable examples include hydraulic cements comprising calcium, magnesium, aluminum, silicon, oxygen, and / or sulfur which set and harden upon reaction with water. Such hydraulic cements include, but are not limited to, Portland cements, pozzolan cements, gypsum cements, high alumina cements, slag cements, silica cements, magnesium cements (commonly called "Sorel cements"), and combinations thereof. In certain embodiments, the cement may comprise a Portland cement. In some embodiments, Portland cements that are suitable for use in the present invention are classified as Class A, C, H, and G according to the American Petroleum Institute, API Specification for Well Cement Materials and Testing, API Specification 10 , 5th Edition, July 1, 1990. The cement compositions of the present invention further comprise a carboxylated particulate elastomer. In some embodiments, the carboxylated elastomer is crosslinked. The particulate elastomers should generally be able to retain their particle nature under well-digging conditions, for example, after introduction to the underground formation. In some embodiments, these particulate elastomers are thermoplastic, wherein the particulate elastomers can melt upon heating and solidify upon cooling.

This fusion and cooling can be repeated, depending on the temperature changes. Among other things, the particulate carboxylated elastomers may allow the concrete cover to withstand stresses that may otherwise lead to failure (eg, cracking, fracturing, detachment, etc.). Referring now to Figure 1, the stress arrest due to the carboxylated elastomer 100 in particles is illustrated schematically. For example, the carboxylated elastomer 100 can act to further prevent the propagation of cracking 102 in the matrix 104 of the cement. In addition, the inclusion of carboxy groups in the particulate elastomers adds polar functional groups to the elastomer. Due to this added polarity, the particulate carboxylated elastomer must generally be able to bond with the cement matrix. Additionally, the carboxy group should generally provide improved adhesion to metal surfaces (e.g., the tube of intubation) due to an ionic bond between the metal ions (e.g., iron (3+) ions) on the oxidized surface of the tube. of intubation and carboxy groups. The carboxy group also generally must provide improved adhesion to the forming surfaces, due to an ionic bond between the calcium ions on the forming surfaces and the carboxy groups. Such improved bonding can provide improved cut resistance which leads to a lockout protection due to the shear stresses between the set cement and the casing tube and / or between the formation and the set cement. These particulate carboxylated elastomers can act to provide resilience and impact resistance to the set cement composition. The particulate carboxylated elastomers can also improve the mechanical properties of the set cement composition, for example, by increasing the tensile strength and the compressive strength and / or decreasing the Young's modulus. Particulate carboxylated elastomers can also facilitate the preparation of uniform blends because the particulate carboxylated elastomers can form water-stable suspensions. Suitable carboxy groups which may be substituents on an elastomer include, but are not limited to, any group containing a carbon atom that is bonded by a double bond to an oxygen atom, by a single bond to another carbon, and by another simple bond to an oxygen, nitrogen, sulfur, or other carboxy carbon. A suitable carboxy group contained in the particulate elastomer can be represented by the general formula COOR, wherein R can be a hydrogen, a metal (eg, an alkali metal, an alkaline earth metal, or a transition metal), a group ammonium or a quaternary ammonium group, an acyl group (eg, acetyl group (CH3C (0)), an alkyl group (such as an ester), an acid anhydride group, and combinations thereof Examples of suitable carboxy groups include, but are not limited to, carboxylic acid, carboxy esters, carboxylic acid anhydrides, and monovalent, divalent, and trivalent metal salts of carboxy acids, derivatives thereof, and combinations thereof In some embodiments, the elastomers in particles can be modified with carboxylic acid derivatives that can potentially generate carboxy groups represented by the general formula COOR, when exposed to aqueous fluids under basic conditions (for example p, the pH> 7) and / or at elevated temperatures. Cement compositions, particularly those containing Portland cement, generally have pH values greater than about 10. Examples of carboxylic acid derivatives that can generate suitable carboxy groups include amides (-C (O) NHR ', wherein R' can be a hydrogen, an alkyl group, a hydroxyalkyl group, or a 2-methyl-l-propane sulfonic acid or its salts). The carboxy groups may be present in the elastomer in particles in an amount sufficient to provide the desired polarity. In some modalities, the carboxy group may be present in the particulate elastomer in an amount in the range of about 0.01% to about 20% by weight of the particulate elastomer. In some embodiments, the carboxy group may be present in the particulate elastomer in an amount in the range of about 0.5% to about 10% by weight of the particulate elastomer. The introduction of the carboxy groups into the particulate elastomer can be carried out by a variety of different methods. In some embodiments, the carboxy groups may be introduced during the polymerization of the elastomer by copolymerization with a monomer comprising a carboxy group. In some embodiments, the carboxy groups can be introduced by grafting carboxy groups onto a particulate hydrophobic elastomer. One method for introducing the carboxy groups is by copolymerization with a monomer comprising a carboxy group. For example, an olefinic monomer can be copolymerized with a monomer comprising a carboxy group. Examples of suitable olefinic monomers include, but are not limited to, styrene, vinyltoluene, alpha-methylstyrene, butadiene, isoprene, hexadiene, dichlorovinylidene, vinylchloride, ethylene, propylene, butylene, and isobutylene. Examples of suitable monomers comprising a carboxy group include, but are not limited to, acrylic acid, alkyl acrylate, alkylalkacrylates, maleic anhydride, maleimide, acrylamide and 2-acrylamido-2-methyl-1-propane sulfonic acid. A variety of carboxylated elastomers can be used in different particles that have been prepared by copolymerization. Examples of suitable particulate carboxylated elastomers formed from this copolymerization include, but are not limited to, comonomers of acrylic acid and ethylene, copolymers comprising styrene and esters of acrylic acid, copolymers comprising ethylene and esters of acrylic acid, and combinations of the same. The term "copolymer," as used herein, is not limited to polymers comprising two types of monomer units, but includes any combination of monomers, for example, terpolymers, tetrapolymers, and the like. Additionally, the term "copolymer," or "comonomer," as used herein, is intended to include both the acid form of the copolymer, or comonomer, its derivative forms such as esters, amides, anhydrides, imides, and their various salts . Suitable examples of commercially available ethylene acrylate copolymers are available under the tradenames SURLYN®, AS 1055, and VAMAC® copolymers from Dupont.

Another comonomer of suitable ethylene acrylic acid is commercially available as a water emulsion under the trademark ADCOTE ™ adhesive 37-220 from Rohm and Hass Corporation. An example of a suitable copolymer comprising ethylene and an acrylic acid ester is an experimental product (V-1921601-60) available as a 60% solid emulsion from 3M Corporation. Another example of a suitable copolymer comprising ethylene and an ester of acrylic acid is an experimental product (V-19219) available as an aqueous emulsion from 3M Corporation. According to one embodiment of the present invention, a segment of a carboxylated elastomer that was obtained by copolymerization with a monomer comprising a carboxy group is graphically illustrated below by Formula I. The carboxylated elastomer comprises an elastomeric structure and groups carboxy pendants. Structure of the Elastomer COOR COOR Formula I wherein R can be a hydrogen, a metal (e.g., an alkali metal, an alkaline earth metal, or a transition metal), an ammonium group or a quaternary ammonium group, an acyl group (e.g. acetyl (CH3C (0))), an alkyl group (such as an ester), a group of acid anhydride, and combinations thereof; and Ri can be a hydrogen, an alkyl, or an aryl group. Another exemplary method for introducing the carboxy groups into the particulate elastomer is by grafting carboxy groups onto a particulate hydrophobic elastomer. For example, such grafted carboxyl-grafted elastomer may comprise an elastomer structure and grafting of carboxy groups. Suitable elastomers which can be grafted with the carboxylation materials generally comprise olefinic monomers, including but not limited to, styrene, vinyltoluene, alpha-methylstyrene, butadiene, isoprene, hexadiene, dichlorovinylidene, vinylchloride, acrylonitrile, ethylene, propylene, butylene, isobutylene, and combinations and copolymers thereof. The elastomers containing these olefinic monomers may include random and block copolymers of styrene butadiene, hydrogenated butadiene and styrene butadiene block copolymers, acrylonitrile butadiene styrene ("ABS") copolymers, ethylene-propylene-diene-monomer copolymers (EPDM) ), styrene-acrylic copolymers, acrylonitrile butadiene rubber (NBR) polymers, methylmethacrylate butadiene styrene (MBS) rubbers, and styrene-acrylonitrile rubbers. The carboxy groups can be grafted onto a particulate hydrophobic elastomer to form a suitable grafted particulate elastomer using a variety of suitable carboxylated materials, including, but not limited to, maleic acid, maleic anhydride, and diesters and monoesters of maleic acid , maleimide, fumaric acid and its derivatives, acrylic acid, alkyl acrylate, alkylalkacrylates, acrylamide, 2-acrylamido-2-methyl-l-propanesulfonic acid and its salts. Examples of suitable graft particulate elastomers include, but are not limited to, maleic polybutadienes, styrene butadiene male rubbers ("SBR"), acrylonitrile-styrene-butadiene ("ABS") male rubbers, maleic nitrile-butadiene rubbers. ("NBR"), maleated hydrogenated hydrogenated butadiene acrylonitrile rubbers ("HNBR"), methyl methacrylate butadiene styrene ("MBS") rubbers, ethylene-propylene-diene carboxylated monomer rubbers, carboxylated styrene-acrynitrile rubbers ("SAN") ), carboxylated ethylene propylene diene rubbers ("EPDM"), acrylic rubbers grafted with silicone, and combinations thereof. An example of a suitable hydrogenated butadiene acrylonitrile rubber ("HNBR") which is grafted with the carboxylation materials is available from Lanxess Corporation, Leverkusen, Germany, under the trade name THERBAN® XT. An example of suitable nitrile-butadiene rubbers ("NBR") that are grafted with carboxylation materials are available from Zeon Chemicals, L.P., Louisville, Kentucky, under the trade name NIPOL® NBR 1072 CGX. Examples of suitable butadiene-based rubbers which are grafted with the carboxylation materials are available from Mitsubishi Rayon Company Ltd., Tokyo, Japan, under the tradenames METABLEN® C and E. An example of an acrylic rubber which is grafted with the materials carboxylates is available from Mitsubishi Rayon Company Limited, Tokyo, Japan, under the tradename METABLEN® W. An example of a silicone-based elastomer that is grafted with carboxylation materials is available from Mitsubishi Rayon America Inc., New York, New York under the tradename METABLEN® S. An example of a suitable styrene butadiene-styrene particle elastomer grafted with maleic acid available as an experimental product (Eliokem XPR-100) from Eliokem Corporation. Referring now to Figure 2, the grafted carboxylated elastomer 200 is illustrated graphically, according to one embodiment of the present invention. The grafted carboxylated elastomer 200 comprises the structure 202 of the elastomer and the grafted carboxy groups 204. The grafting of elastomers with carboxylation materials can be achieved by any suitable methodology. In some embodiments, elastomers of suitable grafted particulate materials can be prepared by polymerizing a monomer (carboxylation material) in the presence of a preformed polymer structure (the preformed elastomer). In some embodiments, the preparation of suitable grafted particulate elastomers comprises a graft polymerization method via free radicals. Free radical graft polymerization generally requires mixing a source of radicals (e.g., an organic peroxide), the carboxylation material (e.g., a maleic acid or maleic anhydride), and the elastomer. This mixture can then be reacted by heating without a solvent. Methods of graft polymerization via free radicals are described in the Encyclopedia of Polymer Science and Engineering, Second Edition, vol. 7, pp. 551-579, Wiley Interscience Publications, edited by JJ. Kroschwitz Examples of additional suitable methods of graft polymerizations include grafting by radiation and grafting by plasma, which can be used for grafting on a surface at room temperature. Grafting by polymerization of a carboxylation material in a preformed elastomer results in blocks of grafted material covalently attached to the preformed elastomer, may be the preferred method of obtaining the block polymer structure, in cases where the two blocks (the carboxylation material and the elastomer), are chemically incompatible (for example, highly hydrophobic and highly hydrophilic), and can not be easily copolymerized from a mixture of the monomer. In some embodiments, the grafting of the surface in the elastomer may result in elastomers of grafted particulate materials having a core wrap morphology, wherein the grafted particulate elastomer comprises an elastomer core and a shell comprising the carboxy groups. . Referring now to Figure 3, a segment of grafted particulate elastomer 300 having a core wrap morphology, according to one embodiment of the present invention, is illustrated graphically. The grafted particulate elastomer 300 comprises the elastomer core 302 and the sheath 304 comprising the carboxy groups. The particulate carboxylated elastomers should be present in the cement compositions of the present invention in an amount sufficient to provide the desired mechanical properties, including resilience, compressive strength, and tensile strength. In some embodiments, the carboxylated elastomers in particles are present in the cement compositions of the present invention in an amount in the range, from about 0.5% to about 25% by weight of total solids. As used herein, "by weight of total solids" refers to the weight included in the cement compositions relative to the total weight of the total solids (such as cement, silica, elastomers of particulate materials, etc.) included in the composition of cement. In some embodiments, the particulate carboxylated elastomers are present in an amount in the range of about 1% to about 20% by weight of total solids. In some embodiments, the particulate carboxylated elastomers are present in an amount in the range of about 4% to about 15% by weight total solids. The particulate carboxylated elastomers may have a wide variety of individual particle shapes and sizes suitable for use in the cement compositions of the present invention. The particulate carboxylated elastomers may have well-defined physical forms, as well as irregular geometries, including the physical form of platelets, chips, fibers, flakes, battens, rods, strips, spheroids, hollow beads, toroids, pellets, tablets, or any other another physical form. In some embodiments, the particulate carboxylated elastomers can have an average size in the range of about 5 microns to about 1,500 microns.

In some embodiments, the particulate carboxylated elastomers may have an average size in the range of about 20 microns to about 500 microns. However, the dimensions of the particles outside these defined ranges may also be suitable for particular applications. Optionally, the cement compositions of the present invention may further comprise a particulate hydrophobic elastomer. Although elastomers in hydrophobic particles generally do not bind to the cement matrix, it is believed that the particulate carboxylated elastomers included in the cement compositions of the present invention may act as "coupling agents" or "compatibilizers" between these two phases incompatible, the cement matrix and the particulate hydrophobic elastomer. The phrase "coupling agent," as used herein, refers to a material that aids the binding between two incompatible materials (eg, an inorganic filler in an organic matrix or vice versa) by forming bonds with both materials through appropriate portions of the structure. Thus, for example, the carboxy groups in the carboxylated particulate elastomer should be bound with the ionic and polar cement particles, and the elastomer portion of the carboxylated particulate elastomer should be linked with the hydrophobic elastomer in the cement compositions. Since such materials combine the structural components of two unequal or incompatible materials of separate polarity, and serve to provide structurally homogeneous compounds mutually bonding with materials that are also called "compatibilizers" and which generally must improve the complete adhesion between two incompatible phases in a composite matrix. Any of the elastomers in hydrophobic particles suitable for use in cement works can be used. Examples of elastomers in suitable hydrophobic particles include particulate elastomers based on hydrocarbons. Particulate hydrocarbon-based elastomers that may be included in cement compositions include, but are not limited to, random and block styrene butadiene copolymers, acrylonitrile butadiene styrene ("ABS") copolymers, ethylene-propylene monomer copolymers -diene (EPDM), styrene-acrylic copolymers, butadiene acrylonitrile rubber ("NBR") polymers, styrene-butadiene methyl methacrylate ("MBS") rubbers, styrene-acrylonitrile ("SAN") rubbers, and combinations of same. When present, elastomers in hydrophobic particles may be included in the cement compositions of the present invention in an amount in the range of about 1% to about 50% by weight of total solids. In some embodiments, the elastomers in hydrophobic particles may be present in an amount in the range of about 4% to about 25% by weight of total solids. In some embodiments, the hydrophobic particulate elastomers may be included in the cement compositions in a weight ratio of the particulate hydrophobic elastomer to the carboxylated particulate elastomer in the range of about 20: 1 to about 1:10. In some embodiments, the weight ratio of the hydrophobic particulate elastomer to the carboxylated particulate elastomer may be in the range of about 10: 1 to about 1: 4. In some embodiments, the weight ratio of the hydrophobic particulate elastomer to the carboxylated particulate elastomer may be in the range of about 10: 1 to about 1: 1. Other additives suitable for use in well excavation cementation works can also be added to these compositions. Other additives, include, but are not limited to, foaming agents, defoamers, dispersants, retarders, accelerators, fluid loss control additives, weight agents, vitrified agents, light additives (eg, bentonite, gilsonite, glass spheres, etc.), and fly ash, and combinations thereof. A person skilled in the art, with the benefit of this description, will know the type and amount of additive useful for a particular application and desired result. An exemplary method of the present invention is a cementing method comprising providing a cement composition comprising water, a cement, and a carboxylated particulate elastomer.; and allow the cement composition to set. In some embodiments, the methods of the present invention may further comprise introducing the cement composition into an underground formation. The step of introducing the cement composition may comprise introducing the cement composition into the well bore, for example, into the ring between the borehole wall and a pipe column disposed in the borehole. To facilitate a better understanding of the present invention, examples of certain aspects of some modalities are given. In no way should the examples be read to limit or define the scope of the invention. EXAMPLE 1 Samples of cement slurries were prepared using Class H cement in accordance with API Reco mended Practices 10B, Edition Twenty-two, December 1997. Samples for measurements of mechanical properties were prepared by curing the slurries in 50.8 metal cylinders. mm x 127 mm (2"x 5") at 88 ° C (190 ° F) for 72 hours under a pressure of 210.9 kg / cm2 (3,000 psi). After this, tests were performed to measure the Young's modulus, compressive strength, and the Poisson's ratio in the samples set by charge vs. displacement measurements according to ASTM D3148-02 (Standard Test Method for the Elastic Modulus of Intact Rocky Specimen Uniaxial Compression). The tensile strengths were measured in briquettes (agglomerates) of dog bone using a Tinius-Olsen Frame Instrument in accordance with CRD-C 260-01 at U.S. Army Corps of Engineers' Handbook for Concrete and Cement. Sample No. 1 (comparative) comprised cement, water in an amount of 35.3% by weight of cement ("epdc"), and an elastomer of the styrene butadiene copolymer (FDP 665 from Halliburton Energy Services, Inc.) in an amount of 4% epdc. Sample No. 2 comprised cement, water in an amount of 35.3% epdc, and a styrene butadiene elastomer grafted with maleic acid (Eliokem XPR-100 from Eliokem Corporation) in an amount of 4% epdc. The densities of both Samples No. 1 and Sample No. 2 remained substantially identical to 16.4 ppg. The results of these tests are shown in the following Table. TABLE 1 Accordingly, Example 1 illustrates that the tensile and compressive strengths of cement compositions can be increased by the addition of an elastomer comprising a carboxy group. EXAMPLE 2 Samples of cement slurries were prepared at room temperature and cured at 88 ° C (190 ° F) for 72 hours under a pressure of 210.9 kg / cm2 (3,000 psi) and tested for mechanical properties as described in Example 1. Sample No. 3 (comparative) comprised cement, water in an amount of 35% epdc, and an elastomer of the styrene butadiene copolymer (FDP 665) in an amount of 4% epdc. Sample No. 4 comprised cement, water in an amount of 34.2% epdc, an elastomer of the styrene butadiene copolymer (FDP 665) in an amount of 4% epdc, and an ethylene acrylic copolymer elastomer in an aqueous emulsion (V -19219 of 3M Corporation) in an amount of 1% epdc. Sample No. 5 comprised cement, water in an amount of 34.2% epdc, an elastomer of the styrene butadiene copolymer (FDP 665) in an amount of 4% epdc, and an elastomer of the styrene-maleic ester copolymer in an amount of 1% epdc. The elastomer of the styrene-maleic ester copolymer used in this sample comprised a copolymer of styrene and maleic acid partially esterified with secondary butanol and methanol, obtained from Aldrich Chemical Company. The densities of Sample No. 3, Sample No. 4, and Sample No. 5 were kept substantially identical to 1.97 kg / l (16.4 ppg).

The results of these tests are shown in the following Table. TABLE 2 According to Example 2 it is illustrated that cement compositions with improved tensile strength and / or reduced Young's Modulus can be achieved by the inclusion of a carboxylated elastomer. EXAMPLE 3 Samples of cement slurries were prepared at room temperature and cured for 72 hours under a pressure of 210.9 kg / cm2 (3,000 psi) at two different temperatures, and tested for mechanical properties as described in Example 1. The dog bone samples were cured for the tensile strength tests at 88 ° C (190 ° F), and the cylinders were cured for the uniaxial test at 60 ° C (140 ° F). Sample No. 6 (comparative) comprised cement, water in an amount of 35% epdc, and an elastomer of styrene butadiene copolymer (FDP 665) in an amount of 4% epdc. Sample No. 7 comprised cement, water in an amount of 34.2% epdc, an elastomer of styrene butadiene copolymer (FDP 665) in an amount of 4% epdc, and a styrene butadiene elastomer grafted with maleic acid (Eliokem XPR-100 ) in an amount of 1% epdc. The densities of both Sample No. 6 and Sample No. 7 were kept substantially identical to 1.97 kg / l (16.4 ppg). The results of these tests are shown in the following Table.

TABLE 3 Accordingly, Example 3 illustrates that modifying the elastomer with a carboxylation material (e.g., maleic acid) decreased the Young's modulus of the cement composition such that it is less brittle or brittle. EXAMPLE 4 The sample cement slurries were prepared at room temperature and cured at 88 ° C (190 ° F) for 72 hours under a pressure of 210.9 kg / cm2 (3,000 psi) and tested for mechanical properties as described. described in Example 1.

Sample No. 8 comprised cement, water in an amount of 33.2% epdc, and an elastomer of ethylene copolymer and acrylate ester in an amount of 3.7% epdc. The elastomer of the ethylene acrylate copolymer was obtained as a 60% solid emulsion (V-19219-60) from 3M Corporation. Sample No. 9 comprised cement, water in an amount of 36.3% epdc, and an elastomer of ethylene copolymer and acrylate ester in an amount of 1% epdc. The elastomer of the ethylene acrylate copolymer was obtained as a 60% solid emulsion (V-19219-60) from 3M Corporation. Sample No. 10 comprised cement, water in an amount of 36.3% epdc, and an elastomer of the salt comonomer of acrylic acid and ethylene (ADCOTEMR adhesive 37-220 from Rohm and Hass Corporation) in an amount of 1.86% epdc. The results of these tests are shown in the following Table.

TABLE 4 According to Example 4 it is illustrated that the inclusion of a suitable carboxylated elastomer in a cement composition can provide an improvement in mechanical properties. EXAMPLE 5 The sample cement slurries were prepared at room temperature and tested for the strength of the shear bond. To measure the resistance to the cutting of the sample applied to metal surfaces, the cement slurries of the sample were allowed to set in the crowns of the pipe assembly, that is, small pipes centered inside larger pipes. The molds were cured at 82 ° C (180 ° F). After setting, the strength of the shear bond of each portion was determined by supporting the larger pipe and applying force to the smaller inner pipe. The cut resistance in the joint is the total applied force divided by the area of the bonded surface that breaks. Sample No. 11 comprised cement, water in an amount of 36.3% epdc, and a comonomer of the acrylic acid and ethylene salt (ADCOTE ™ adhesive 37-220) in an amount of 0.93% epdc. The particulate elastomer containing carboxy was included in this sample. Sample No. 12 comprised cement, water in an amount of 37.2% epdc, and a salt comonomer of acrylic acid and ethylene (ADCOTE ™ adhesive 37-220) in an amount of 0.45% epdc. Sample No. 13 (comparative) comprised cement and water in an amount of 39.0% epdc. The densities of Sample No. 11, Sample No. 12, and Sample No. 13 were kept substantially identical to 1.97 kg / l (16.4 ppg). The results of these tests are shown in the following Table.

TABLE 5 According to Example 5 it is illustrated that the inclusion of a carboxylated elastomer in a cement composition can provide improved cut resistance. EXAMPLE 6 The effects of carboxylation on the strength of the cement compositions at cyclic stresses induced by the axial stress cycle were studied by comparing a composition containing the base elastomer used to graft with carboxy groups to that containing the elastomer. that has been grafted with the carboxy groups. Accordingly, Sample No. 14 was prepared and cured under conditions identical to those used to prepare and cure Sample No. 2 with the exception that the butadiene styrene elastomer grafted with maleic acid (Eliokem XPR-100 from Eliokem Corporation) was replaced with 8% epdc of an ungrafted styrene butadiene elastomer (Eliokem XPR-99 from Eliokem Corporation), and the density of the slurry was 1.92 kg / l (16.0 ppg). Sample No. 15 was prepared and cured under conditions identical to those used for the preparation and curing of Sample No. 2 except that the amount of the styrene butadiene elastomer grafted with maleic acid (Eliokem XPR-100 from Eliokem Corporation) was increased to 8% epdc, and the density of the slurry was 1.92 kg / l (16.0 ppg). Cyclic tests were designed to provide data on cement response to initial load cycles that start at 50% compressive strength and increase 10% compressive strength per cycle at the last level. The final level was adjusted to the lowest value of two standard deviations below the compressive strength, or 90% compressive strength. The low tension level was adjusted to the larger value of 7.0 kg / cm2 i (100 ps), or 10% compressive strength. The initial partial charge cycles were developed under displacement control at a displacement ratio of 5 E-5 inches per second (12.7 E-5 cm per second), to equalize the displacement ratio of stress-strain tests. The cyclic portion of the tests was run under force control with the first 10 cycles at 4 minutes per cycle, the next 50 cycles at 2 minutes per cycle, the following 190 cycles at 1 minute per cycle, and the last cycles at 30 seconds per cycle. Sample No. 15 lasted an average of 240 cycles before failure, while samples of Composition No. 14 lasted 158 cycles indicating that grafting with carboxy groups improved the cyclic strength of the cement compositions. Accordingly, the present invention is well adapted to achieve the ends and advantages mentioned as well as those which are inherent. The particular embodiments described above are illustrative only, when the present invention can be modified and practiced in different but equivalent apparent ways to those skilled in the art, which have the benefit of the teachings herein. In addition, no limitation is intended to the details of construction or design shown herein, or other than that described in the claims below. It is therefore evident that the particular illustrative embodiments described above may be altered or modified and that all such variations are considered within the scope and spirit of the present invention. In particular, each range of values (of the form, "from about a to about b," or, equivalently, "from about a to b," or, equivalently, "from about ab") described herein will be understood to be refer to the application of forces (the sets of all sets) of the respective ranges of values, and stipulated in each range covered within the widest range of values. Also, the terms in the claims will have their plan, ordinary meaning unless they are explicitly and clearly defined by the holder of a patent.

Claims (42)

1. NOVELTY OF THE INVENTION Having described the invention as above, property is claimed as contained in the following: CLAIMS 1. A cement composition characterized by comprising: water; a cement; and a particulate elastomer comprising a carboxy group.
2. 2. The cement composition according to claim 1, characterized in that the carboxy group has the formula COOR wherein R is a hydrogen, a metal, an ammonium group, a quaternary ammonium group, an acyl group, an alkyl group, a acid anhydride group, or a combination thereof.
3. 3. The cement composition according to claim 1, characterized in that the particulate elastomer is modified by a carboxylic acid derivative that generates the carboxy group.
4. 4. The cement composition according to claim 3, characterized in that the carboxylic acid derivative is an amide.
5. 5. The cement composition according to claim 1, characterized in that the carboxy group is present in the particulate elastomer in an amount in the range of from about 0.01% to about 20% by weight of the particulate elastomer.
6. 6. The cement composition according to claim 1, characterized in that the carboxy group is introduced into the particulate elastomer by the copolymerization of an olefinic monomer and a monomer comprising the carboxy group.
7. The cement composition according to claim 1, characterized in that the particulate elastomer comprises at least one elastomer selected from the group consisting of a comonomer of ethylene acrylic acid, a copolymer comprising styrene and an acrylic acid ester , a copolymer comprising ethylene and an ester of acrylic acid, and combinations thereof.
8. The cement composition according to claim 1, characterized in that the particulate elastomer is a particulate elastomer graft comprising a hydrophobic elastomer grafted with a carboxylation material.
9. 9. The cement composition according to claim 1, characterized in that the particulate elastomer is a graft of the particulate elastomer comprising a structure of the elastomer and grafting of carboxy groups.
10. 10. The cement composition according to claim 1, characterized in that the particulate elastomer comprises a particulate elastomer graft selected from the group consisting of a maleated polybutadiene, a maleated styrene-butadiene rubber, acrylonitrile-styrene-butadiene rubber. malleable nitrile-butadiene rubber, a maleated hydrogenated acrylonitrile butadiene rubber, a styrene-butadiene rubber of methylmethacrylate, a carboxylated ethylene-propylene-diene monomer rubber, a carboxylated styrene-acrynitrile rubber, a diene rubber carboxylated ethylene propylene, an acrylic rubber grafted with silicone, and combinations thereof.
11. The cement composition according to claim 1, characterized in that the particulate elastomer has a core wrap morphology, the particulate elastomer comprising an elastomer core and a shell comprising the carboxy group.
12. 12. The cement composition according to claim 1, characterized in that the particulate elastomer is present in the cement composition in an amount in the range of about 0.5% to about 25% by weight of total solids present in the composition of the composition. cement.
13. 13. The cement composition according to claim 1, characterized in that the particulate elastomer has a medium size in the range of about 5 microns to about 1,500 microns.
14. 14. The cement composition according to claim 1, characterized in that the cement composition also comprises, a hydrophobic particulate elastomer.
15. 15. The cement composition according to claim 1, characterized in that the cement composition comprises a particulate hydrophobic elastomer selected from the group consisting of a random butadiene styrene copolymer, a styrene butadiene block copolymer, an acrylonitrile copolymer butadiene styrene, a copolymer of the ethylene-propylene-diene monomer, a styrene-acrylic copolymer, an acrylonitrile butadiene rubber polymer, a methylmethacrylate butadiene styrene rubber, a styrene-acrynitrile rubber, and combinations thereof.
16. 16. A cement composition characterized in that it comprises: water; a cement; a particulate elastomer comprising a carboxy group; and a particulate hydrophobic elastomer.
17. 17. The cement composition according to claim 16, characterized in that the carboxy group is introduced into the particulate elastomer by the copolymerization of an olefinic monomer and a monomer comprising the carboxy group.
18. 18. The cement composition according to claim 16, characterized in that the particulate elastomer is a grafted particulate elastomer comprising a particulate hydrophobic elastomer grafted with a carboxylation material.
19. 19. The cement composition according to claim 16, characterized in that the particulate hydrophobic elastomer is selected from the group consisting of a group of a random copolymer of styrene butadiene, a block copolymer of styrene butadiene, an acrylonitrile butadiene styrene copolymer , a copolymer of ethylene-propylene-diene monomer, a styrene-acrylic copolymer, an acrylonitrile butadiene rubber polymer, a methylmethacrylate butadiene styrene rubber, a styrene-acrynitrile rubber, and combinations thereof.
20. 20. The cement composition according to claim 16, characterized in that the particulate hydrophobic elastomer is present in a weight ratio of particulate hydrophobic elastomer to particulate elastomer in the range of from about 20: 1 to about 1. : 10 21.
21. A cementing method characterized in that it comprises: providing a cement composition comprising water, a cement, and a particulate elastomer comprising a carboxy group; and allow the cement composition to set.
22. The method according to claim 21, characterized in that the carboxy group has the formula COOR wherein R is a hydrogen, a metal, an ammonium group, a quaternary ammonium group, an acyl group, an alkyl group, an anhydride group of acid, or a combination thereof.
23. 23. The method according to claim 21, characterized in that the particulate elastomer is modified by a carboxylic acid derivative that generates the carboxy group.
24. The method according to claim 21, characterized in that the carboxy group is present in the particulate elastomer in an amount in the range from about 0.01% to about 20% by weight of the particulate elastomer.
25. 25. The method according to claim 21, characterized in that the carboxy group is introduced into the particulate elastomer by the copolymerization of an olefinic monomer and a monomer comprising a carboxy group.
26. The method according to claim 21, characterized in that the particulate elastomer comprises at least one elastomer selected from the group consisting of a comonomer of acrylic acid and ethylene, a copolymer comprising styrene and an ester of acrylic acid, a copolymer comprising ethylene and an ester of acrylic acid, and combinations thereof.
27. 27. The method according to claim 21, characterized in that the particulate elastomer is a particulate elastomer graft comprising a hydrophobic elastomer grafted with a carboxylation material.
28. The method according to claim 21, characterized in that the particulate elastomer comprises a particulate elastomer graft selected from the group consisting of a maleated polybutadiene, a maleated styrene-butadiene rubber, a maleated acrylonitrile-styrene-butadiene rubber , a maleated nitrile-butadiene rubber, a maleated hydrogenated acrylonitrile butadiene rubber, a methylmethacrylate butadiene styrene rubber, a carboxylated ethylene-propylene-diene monomer rubber, a carboxylated styrene-acrynitrile rubber, an ethylene propylene diene rubber carboxylated, an acrylic rubber grafted with silicone and combinations thereof.
29. 29. The method according to claim 21, characterized in that the particulate elastomer is present in the cement composition in an amount in the range of from about 0.5% to about 25% by weight of total solids present in the cement composition.
30. 30. The method according to claim 21, characterized in that the cement composition further comprises a particulate hydrophobic elastomer.
31. The method according to claim 21, characterized in that the cement composition comprises a hydrophobic particulate elastomer selected from the group consisting of a styrene butadiene random copolymer, a styrene butadiene block copolymer, an acrylonitrile butadiene styrene copolymer , a monomer-ethylene-propylene-diene copolymer, a styrene-acrylic copolymer, an acrylonitrile butadiene rubber polymer, a methylmethacrylate butadiene styrene rubber, a styrene-acrynitrile rubber, and combinations thereof.
32. 32. A cementing method characterized in that it comprises: providing a cement composition comprising water, a cement, and a particulate elastomer comprising a carboxy group; introduce the cement composition in an underground formation; and allow the cement composition to set there.
33. 33. The method according to claim 32, characterized in that the particulate elastomer is modified by a carboxylic acid derivative that generates the carboxy group.
34. 34. The method according to claim 32, characterized in that the carboxy group is introduced into the particulate elastomer by the copolymerization of an olefinic monomer and a monomer comprising a carboxy group.
35. 35. The method according to claim 32, characterized in that the particulate elastomer comprises at least one elastomer selected from the group consisting of a comonomer of acrylic acid and ethylene, a copolymer comprising styrene and an ester of acrylic acid, a copolymer comprising ethylene and an ester of acrylic acid, and combinations thereof.
36. 36. The method according to claim 32, characterized in that the particulate elastomer is a particulate elastomer graft comprising a hydrophobic elastomer grafted with a carboxylation material.
37. 37. The method according to claim 32, characterized in that the particulate elastomer comprises a particulate elastomer graft selected from the group consisting of a maleated polybutadiene, a maleated styrene-butadiene rubber, a maleated acrylonitrile-styrene-butadiene rubber. , a maleated nitrile-butadiene rubber, a maleated hydrogenated acrylonitrile butadiene rubber, a methylmethacrylate butadiene styrene rubber, a carboxylated ethylene-propylene-diene monomer rubber, a carboxylated styrene-acrynitrile rubber, an ethylene propylene diene rubber carboxylated, an acrylic rubber grafted with silicone and combinations thereof.
38. 38. The method according to claim 32, characterized in that the cement composition further comprises a particulate hydrophobic elastomer.
39. 39. The method according to claim 32, characterized in that the cement composition is introduced in a ring between a wall of a drill hole penetrating the underground formation and a column of pipe arranged in the drill hole.
40. 40. A method for improving the mechanical properties of a cement composition, characterized in that it comprises: including a particulate elastomer comprising a carboxy group in the cement composition such that the cement composition comprises water, a cement, and the elastomer in particles; introduce the cement composition in an underground formation; and allow the cement composition to set there.
41. 41. A method for improving adhesion between a cement composition and a tubing pipe and / or an underground formation comprising: including a particulate elastomer comprising a carboxy group in the cement composition such that the cement composition include water, a cement, and particulate elastomer; introduce the cementing composition in the underground formation; allow the cement composition to set there.
42. 42. The method according to claim 41, characterized in that the cement composition is introduced into a ring between a wall of a drill hole penetrating the underground formation and a column of pipe arranged in the drill hole.