An interface reinforcing material for cementing and a preparation method thereof

Abstract

The application provides an interface reinforcing material for cementing and a preparation method, which comprises the following components in parts by weight: 100 parts of a styrene-based monomer, 30-50 parts of an acrylic ester monomer, 5-10 parts of graphene oxide, 3-5 parts of an organosiloxane, 3-5 parts of an anionic monomer, 3-5 parts of a cationic monomer, 3-5 parts of a large steric hindrance crosslinking agent, 0.5-1.5 parts of a photoinitiator, and 200-300 parts of deionized water. The application can effectively improve the oil absorption network volume and oil absorption rate through the recrosslinking between macromolecular microspheres, improve the oil absorption effect, realize the selective adsorption of oil phase in water through the excellent specific surface area and hydrophobic and oleophilic characteristics of the modified graphene oxide, and reduce the influence of the material on the cement hydration process. The introduction of the anionic and cationic monomers improves the stability of the polymerization reaction and the dispersion performance of the material in the cement slurry, and the synergistic effect of the ionic bonds helps to improve the toughness of the material and the cement stone.

Description

Technical Field

[0001] This invention relates to the field of oilfield cementing technology, and more specifically, to an interface reinforcement material for cementing and its preparation method. Background Technology

[0002] In the cementing process of oil and gas wells, the bonding quality between the cement sheath and the casing and wellbore is a crucial factor affecting the final cementing quality. Good interfacial bonding can improve the interlayer sealing effect of cementing, prevent oil-water cross-flow, and ensure the production rate and lifespan of oil and gas wells. In recent years, oil-based drilling fluids have been widely used in complex deep wells and unconventional horizontal well operations in mudstone, shale, and salt gypsum layers due to their good lubricity, inhibition, and anti-fouling properties. However, during construction, they are prone to stagnation in narrow annulus spaces and irregular well diameter areas, and often form oil films on the wellbore and casing surfaces. When mixed with cement slurry, these oil films can affect the fluidity and thickening properties of the cement slurry, significantly reduce the bulk strength of the cement stone after solidification, and compromise the bonding quality of the first and second interfaces, affecting the integrity of the cement sheath and the interlayer sealing capacity, thus seriously jeopardizing the cementing quality.

[0003] To address the problem of poor cementing quality at the well interface caused by oil-based drilling fluid contamination, the main approach is to develop highly efficient oil-washing pre-flush fluids. These fluids utilize lipophilic surfactants to effectively adsorb and remove the oil phase at the interface. Based on this, microemulsions and nanoemulsions have been developed as pre-flush fluid systems, and current research primarily focuses on pre-flush fluids. However, due to limitations imposed by factors such as contact time, wellbore conditions, temperature, and drilling fluid composition, it is often difficult to completely remove oil-based drilling fluids solely from the perspective of pre-flush fluids. Summary of the Invention

[0004] In view of this, the present invention proposes an interface reinforcement material for cementing and its preparation method, aiming to solve the above-mentioned technical problems existing in the prior art.

[0005] The first aspect of this invention provides an interface reinforcement material for cementing, comprising the following components in parts by weight: 100 parts by weight of styrene-based monomers, 30-50 parts by weight of acrylate monomers, 5-10 parts by weight of graphene oxide, 3-5 parts by weight of organosiloxanes, 3-5 parts by weight of anionic monomers, 3-5 parts by weight of cationic monomers, 3-5 parts by weight of a sterically hindered crosslinking agent, 0.5-1.5 parts by weight of a photoinitiator, and 200-300 parts by weight of deionized water.

[0006] Furthermore, in the above-mentioned cementing interface reinforcement material, the styrene-based monomer is styrene, methylstyrene, or tert-butylstyrene.

[0007] Furthermore, in the above-mentioned cementing interface reinforcement material, the acrylate monomers are methyl acrylate, butyl acrylate, octadecyl acrylate, dodecyl methacrylate, or isooctyl methacrylate.

[0008] Furthermore, in the above-mentioned cementing interface reinforcement material, the organosiloxane is vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, or γ-(methacryloyloxy)propyltrimethoxysilane.

[0009] Furthermore, in the above-mentioned cementing interface reinforcement material, the anionic monomer is 2-acrylamide-2-methylpropanesulfonate, sodium p-styrenesulfonate, or 2-methacryloyloxyethanesulfonate.

[0010] Furthermore, in the above-mentioned cementing interface reinforcement material, the cationic monomer is diallyl dimethyl ammonium chloride, diallyl diethyl ammonium chloride, or (3-acrylamidopropyl)trimethyl ammonium chloride.

[0011] Furthermore, in the above-mentioned cementing interface reinforcement material, the steric hindrance crosslinking agent is ethylene glycol dicyclopentenyl ether acrylate, ethylene glycol dicyclopentenyl ether methacrylate, or pentaerythritol triacrylate.

[0012] Furthermore, in the above-mentioned cementing interface reinforcement material, the photoinitiator is benzoin dimethyl ether, diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride, or 2,2-diethoxyacetophenone.

[0013] The first aspect of this invention provides an interface reinforcement material for cementing, which, by using amphiphilic macromolecular microspheres as the rigid framework of a composite gel, together with introduced graphene oxide, endows the material with excellent mechanical properties; the re-crosslinking between macromolecular microspheres can effectively increase the oil-absorbing network volume and oil adsorption rate, thereby improving the oil absorption effect; the excellent specific surface area and hydrophobic and oleophilic properties of modified graphene oxide can achieve selective adsorption of oil phase in water, reducing the material's impact on the cement hydration process; the introduction of anionic and cationic monomers improves the stability of the polymerization reaction and the dispersion performance of the material in cement slurry, while the synergistic effect of ionic bonds helps to improve the toughness of the material and cement paste.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned interface reinforcement material for cementing, comprising the following steps:

[0015] A suitable amount of organosiloxane is uniformly dispersed in anhydrous ethanol to obtain a siloxane solution. Graphene oxide is dispersed in the siloxane solution, stirred at a preset temperature for a period of time, centrifuged, washed, separated again, and dried to obtain modified graphene oxide.

[0016] Take 0.5 to 1.5 parts of photoinitiator and disperse it evenly in 5 to 15 parts of deionized water to obtain the initiator solution;

[0017] According to the weight proportions of each component, styrene-based monomers, acrylate monomers, anionic monomers, cationic monomers, sterically hindered crosslinking agents, photoinitiator solutions, and deionized water are added to a reactor under light-shielded conditions. After stirring and dissolving, ultraviolet light is used to initiate the reaction for a first preset time under a nitrogen atmosphere to obtain an aqueous solution of macromolecular microspheres. After cooling to room temperature, modified graphene oxide is added to the above aqueous solution of macromolecular microspheres. After stirring and mixing, ultraviolet light is used to initiate the reaction for a second preset time under a nitrogen atmosphere to obtain a composite polymer hydrogel. After drying, pulverizing, and sieving, an interface reinforcement material for cementing can be obtained.

[0018] Furthermore, in the above-mentioned method for preparing interface reinforcement materials for cementing, the first preset time is 0.5-3h; the second preset time is 0.5-2h.

[0019] The preparation method of the cementing interface reinforcement material provided in the second aspect of the present invention adopts a segmented photo-initiated polymerization process, which can precisely control the crosslinking degree of the macromolecular microspheres themselves and the composite gel network formed by them through photo-initiation time, thereby achieving balanced regulation of the material's mechanical properties and oil absorption effect, while also having the advantages of low energy consumption and high efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of the preparation method of the interface reinforcement material for cementing in an embodiment of the present invention;

[0021] Figure 2A SEM image of the interface between the cement paste and the core after separation;

[0022] Figure 2B SEM image of the interface between the cement stone and the core after separation, incorporating the interface reinforcement material for cementing in Example 5 of this invention. Detailed Implementation

[0023] The following describes preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

[0024] This invention provides an interface reinforcement material for cementing, comprising the following components in parts by weight: 100 parts styrene-based monomers, 30-50 parts acrylate monomers, 5-10 parts graphene oxide, 3-5 parts organosiloxanes, 3-5 parts anionic monomers, 3-5 parts cationic monomers, 3-5 parts sterically hindered crosslinking agents, 0.5-1.5 parts photoinitiator, and 200-300 parts deionized water.

[0025] Specifically, the styrene-based monomer is styrene, methylstyrene, or tert-butylstyrene. Styrene-based monomers primarily function as rigid groups, imparting good mechanical properties to the material.

[0026] The acrylate monomers are methyl acrylate, butyl acrylate, octadecyl acrylate, dodecyl methacrylate, or isooctyl methacrylate. These acrylate monomers impart flexibility to the material's molecular chains, allowing for selective adsorption of the oil phase based on the principle of "like dissolves like."

[0027] Graphene oxide is commercially available graphene oxide powder with a sheet diameter of 0.2–10 μm and a thickness of 0.5–1.2 nm.

[0028] The organosiloxane is vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, or γ-(methacryloyloxy)propyltrimethoxysilane.

[0029] The anionic monomer is 2-acrylamide-2-methylpropanesulfonate, sodium p-styrenesulfonate, or 2-methacryloyloxyethanesulfonate.

[0030] The cationic monomer is diallyl dimethyl ammonium chloride, diallyl diethyl ammonium chloride, or (3-acrylamidopropyl)trimethyl ammonium chloride.

[0031] In this embodiment, ionic bonds can be formed between anionic and cationic monomers, creating new crosslinking sites within the system, which can improve the mechanical strength of the material and achieve a toughening effect.

[0032] The sterically hindered crosslinking agent is ethylene glycol dicyclopentenyl ether acrylate, ethylene glycol dicyclopentenyl ether methacrylate, or pentaerythritol triacrylate. In this embodiment, a sterically hindered crosslinking agent is chosen because its large steric hindrance allows the residual double bonds after the primary initiation to be exposed on the outside of the macromolecular microspheres, thus serving as new crosslinking sites for further polymerization with the introduced modified graphene oxide, ultimately forming a composite polymer gel network structure.

[0033] The photoinitiator is benzoin dimethyl ether, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, or 2,2-diethoxyacetophenone.

[0034] The cementing interface reinforcement material prepared in this invention first copolymerizes styrene-based monomers, acrylate monomers, anionic monomers, and cationic monomers to form amphiphilic macromolecular microspheres with a three-dimensional network structure. These amphiphilic macromolecular microspheres serve as the rigid framework of the composite gel, and together with introduced graphene oxide, impart excellent mechanical properties to the material. The re-crosslinking between the macromolecular microspheres effectively increases the oil-absorbing network volume and oil adsorption rate, thus improving the oil absorption effect. The excellent specific surface area and hydrophobic-oleophilic properties of modified graphene oxide enable selective adsorption of the oil phase in water, reducing the material's impact on the cement hydration process. The introduction of hydrophilic groups through anionic and cationic monomers imbues the particles with hydrophilic properties, which helps stabilize polymer emulsion particles, improves emulsion stability, and enhances the redispersibility of polymer powder in cement slurry. Simultaneously, the synergistic effect of ionic bonds helps improve the toughness of the material and cement paste.

[0035] This invention also provides a method for preparing an interface reinforcement material for cementing, comprising the following steps:

[0036] Step 1: Disperse an appropriate amount of organosiloxane evenly in anhydrous ethanol to obtain a siloxane solution. Disperse graphene oxide in the siloxane solution, stir for a period of time at a preset temperature, centrifuge to separate, wash, separate again, and dry to obtain modified graphene oxide.

[0037] Specifically, 15-25g of siloxane can be placed in 1L of ethanol solution. Graphene oxide can be dispersed in the siloxane solution using ultrasound. The preset temperature is 40-80℃, preferably 60℃. The stirring time can be 4-10 hours, preferably 5 hours. In practice, the graphene oxide siloxane solution can be washed multiple times with deionized water, followed by a second separation. After the second centrifugation, the solution is dried in a forced-air drying oven.

[0038] Step 2: Take 0.5 to 1.5 parts of photoinitiator and disperse it evenly in 5 to 15 parts of deionized water to obtain the initiator solution.

[0039] Step 3: According to the weight proportions of each component, add styrene-based monomers, acrylate monomers, anionic monomers, cationic monomers, sterically hindered crosslinking agents, photoinitiator solutions, and deionized water to the reactor under light-protected conditions. After stirring and dissolving, initiate the reaction with ultraviolet light for a first preset time under a nitrogen atmosphere to obtain a macromolecular microsphere aqueous solution. After cooling to room temperature, add modified graphene oxide to the above macromolecular microsphere aqueous solution, stir and mix well, and continue to initiate the reaction with ultraviolet light for a second preset time under a nitrogen atmosphere to obtain a composite polymer hydrogel. After drying, pulverizing, and sieving, the interface reinforcement material for cementing can be obtained.

[0040] Specifically, nitrogen bubbling can be used to stir and dissolve the microspheres. In this embodiment, the macromolecular microspheres are prepared by irradiation with a high-pressure ultraviolet mercury lamp under a nitrogen atmosphere. The photoinitiator decomposes into free radicals under ultraviolet light irradiation, thereby initiating monomer polymerization and cross-linking to form macromolecular microspheres.

[0041] Since the photoinitiation time determines the degree of crosslinking of the polymer gel network, the degree of crosslinking increases continuously with the reaction over a certain period until it tends to reach equilibrium. Increased crosslinking improves the mechanical properties of the material, but decreases its oil absorption and swelling capacity. Therefore, it is necessary to select appropriate time points during polymerization to ensure that the degree of crosslinking of the macromolecular microspheres and the composite gel network is controlled within a certain range, so that the material can achieve both good mechanical strength and oil absorption. Excessive polymerization time can lead to a certain degree of polymer degradation, affecting the product performance. Therefore, in this embodiment, the first preset time is 0.5-3 hours, preferably 1 hour; the second preset time is 0.5-2 hours, preferably 0.5 hours.

[0042] Since excessively large particle size can affect the mechanical strength of cement stone, while excessively small particle size can lead to poor cement slurry flow, a vibrating screen with a sieve particle size of 40-100 mesh can be used to sieve the dried and pulverized composite polymer hydrogel. Preferably, a vibrating screen with a sieve particle size of 80 mesh is used.

[0043] It should be noted that, in practice, the order of steps 1 and 2 is not important.

[0044] The method for preparing interface reinforcement materials for cementing provided by this invention adopts a segmented photo-initiated polymerization process. The crosslinking degree of the macromolecular microspheres and the composite gel network they form can be precisely controlled by the photo-initiation time, so as to achieve a balanced regulation of the material's mechanical properties and oil absorption effect. At the same time, it has the advantages of low energy consumption and high efficiency.

[0045] The present invention will now be described in detail with reference to several embodiments.

[0046] Example 1

[0047] (1) Modification of graphene oxide: 15g of allyltrimethoxysilane was uniformly dispersed in 1L of anhydrous ethanol to obtain a siloxane solution. Graphene oxide was ultrasonically dispersed in the siloxane solution, stirred at 60℃ for 5h, centrifuged, washed multiple times with deionized water, and dried in a forced-air drying oven after centrifugation.

[0048] (2) Preparation of initiator solution: Take 2.5g of benzoin dimethyl ether and disperse it evenly in 50g of deionized water to obtain initiator solution;

[0049] (3) According to the weight proportions of each component, 500g of styrene, 150g of methyl acrylate, 15g of 2-acrylamide-2-methylpropanesulfonate, 15g of diallyl dimethyl ammonium chloride, 15g of ethylene glycol dicyclopentenyl ether acrylate, 950g of deionized water and initiator solution were added to the reactor under light-protected conditions. After dissolving by bubbling and stirring with nitrogen gas, the solution was irradiated with a high-pressure mercury lamp under a nitrogen atmosphere for 1 hour to obtain an aqueous solution of macromolecular microspheres. After the temperature was cooled to room temperature, 25g of modified graphene oxide was added, stirred and mixed, and then the solution was further initiated under a nitrogen atmosphere for 0.5 hours to obtain a composite polymer hydrogel. After drying and pulverizing, the solution was passed through an 80-mesh vibrating sieve to obtain the interface reinforcement material for cementing.

[0050] Example 2

[0051] (1) Modification of graphene oxide: 25g of vinyltris(β-methoxyethoxy)silane was uniformly dispersed in 1L of anhydrous ethanol to obtain a siloxane solution. Graphene oxide was ultrasonically dispersed in the siloxane solution, stirred at 60℃ for 5h, centrifuged, washed multiple times with deionized water, and dried in a forced-air drying oven after centrifugation.

[0052] (2) Preparation of initiator solution: Take 7.5g of benzoin dimethyl ether and disperse it evenly in 50g of deionized water to obtain initiator solution.

[0053] (3) According to the weight proportions of each component, 500g of methylstyrene, 250g of butyl acrylate, 25g of sodium p-styrene sulfonate, 25g of diallyl diethylammonium chloride, 25g of ethylene glycol dicyclopentenyl ether methacrylate, 1450g of deionized water and initiator solution were added to the reactor under light-protected conditions. After dissolving by bubbling and stirring with nitrogen gas, the mixture was irradiated with a high-pressure mercury lamp under a nitrogen atmosphere for 1 hour to obtain an aqueous solution of macromolecular microspheres. After the temperature was cooled to room temperature, 50g of modified graphene oxide was added, and the mixture was stirred and mixed. The mixture was then further initiated under a nitrogen atmosphere for 1 hour to obtain a composite polymer hydrogel. After drying and pulverizing the hydrogel through an 80-mesh vibrating sieve, the interface reinforcement material for cementing was obtained.

[0054] Example 3

[0055] (1) Modification of graphene oxide: 20g of vinyltrimethoxysilane was uniformly dispersed in 1L of anhydrous ethanol to obtain a siloxane solution. Graphene oxide was ultrasonically dispersed in the siloxane solution, stirred at 60℃ for 5h, centrifuged, washed multiple times with deionized water, and dried in a forced-air drying oven after centrifugation.

[0056] (2) Preparation of initiator solution: Take 6g of diphenyl-(2,4,6-trimethylbenzoyl)phosphine and disperse it evenly in 50g of deionized water to obtain initiator solution.

[0057] (3) According to the weight proportions of each component, 500g of tert-butylstyrene, 170g of octadecyl acrylate, 18g of 2-methacryloyloxyethanesulfonate, 22g of (3-acrylamidopropyl)trimethylammonium chloride, 18g of pentaerythritol triacrylate, 1250g of deionized water and initiator solution were added to the reactor under light-protected conditions. After dissolving by bubbling and stirring with nitrogen gas, the mixture was irradiated with a high-pressure mercury lamp under a nitrogen atmosphere for 1.5h to obtain an aqueous solution of macromolecular microspheres. After cooling to room temperature, 30g of modified graphene oxide was added, stirred and mixed, and then initiated under a nitrogen atmosphere for another 1h to obtain a composite polymer hydrogel. After drying and pulverizing, the mixture was passed through an 80-mesh vibrating sieve to obtain the interface reinforcement material for cementing.

[0058] Example 4

[0059] (1) Modification of graphene oxide: 25g of vinyltriethoxysilane was uniformly dispersed in 1L of anhydrous ethanol to obtain a siloxane solution. Graphene oxide was ultrasonically dispersed in the siloxane solution, stirred at 60℃ for 5h, centrifuged, washed multiple times with deionized water, and dried in a forced-air drying oven after centrifugation.

[0060] (2) Preparation of initiator solution: Take 3g of benzoin dimethyl ether and disperse it evenly in 50g of deionized water to obtain initiator solution.

[0061] (3) According to the weight proportions of each component, 500g of methylstyrene, 200g of dodecyl methacrylate, 24g of sodium p-styrene sulfonate, 16g of diallyl diethylammonium chloride, 22g of ethylene glycol dicyclopentenyl ether methacrylate, 1150g of deionized water and initiator solution were added to the reactor under light-protected conditions. After dissolving by bubbling and stirring with nitrogen gas, the mixture was irradiated with a high-pressure mercury lamp under a nitrogen atmosphere for 1 hour to obtain an aqueous solution of macromolecular microspheres. After the temperature was cooled to room temperature, 40g of modified graphene oxide was added, and the mixture was stirred and mixed. The mixture was then further initiated under a nitrogen atmosphere for 1 hour to obtain a composite polymer hydrogel. After drying and pulverizing the hydrogel through an 80-mesh vibrating sieve, the interface reinforcement material for cementing was obtained.

[0062] Example 5

[0063] (1) Modification of graphene oxide: 20g of γ-(methacryloyloxy)propyltrimethoxysilane was uniformly dispersed in 1L of anhydrous ethanol to obtain a siloxane solution. Graphene oxide was ultrasonically dispersed in the siloxane solution, stirred at 60℃ for 5h, centrifuged, washed multiple times with deionized water, and dried in a forced-air drying oven after centrifugation.

[0064] (2) Preparation of initiator solution: Take 5g of 2,2-diethoxyacetophenone and disperse it evenly in 50g of deionized water to obtain initiator solution.

[0065] (3) According to the weight proportions of each component, 500g of styrene, 200g of isooctyl methacrylate, 20g of 2-acrylamide-2-methylpropanesulfonate, 20g of (3-acrylamidopropyl)trimethylammonium chloride, 20g of ethylene glycol dicyclopentenyl ether acrylate, 1200g of deionized water and initiator solution were added to the reactor under light-protected conditions. After dissolving by bubbling and stirring with nitrogen, the solution was irradiated with a high-pressure mercury lamp under a nitrogen atmosphere for 1 hour to obtain an aqueous solution of macromolecular microspheres. After cooling to room temperature, 35g of modified graphene oxide was added, stirred and mixed, and then initiated under a nitrogen atmosphere for another 0.5 hours to obtain a composite polymer hydrogel. After drying and pulverizing, the solution was passed through an 80-mesh vibrating sieve to obtain the interface reinforcement material for cementing.

[0066] Comparative Example

[0067] The specific steps of photo-initiated polymerization are as follows: According to the weight proportions of each component, 500g of styrene, 150g of methyl acrylate, 15g of 2-acrylamide-2-methylpropanesulfonate, 15g of diallyl dimethyl ammonium chloride, 25g of modified graphene oxide, 15g of ethylene glycol dicyclopentenyl ether acrylate, 950g of deionized water and initiator solution are added to the reactor under light-protected conditions. After dissolving by bubbling and stirring with nitrogen gas, the polymer hydrogel is obtained by irradiation with an ultraviolet high-pressure mercury lamp under a nitrogen atmosphere for 1.5h. After drying and pulverizing through an 80-mesh vibrating sieve, the interface reinforcement material for cementing is obtained. Except for the above, all other steps are the same as in Example 1.

[0068] Experimental Example 1

[0069] The oil absorption performance of the cementing interface reinforcement materials of each embodiment and comparative example was tested. A certain mass of dried interface reinforcement material (m1) was placed in a non-woven bag and immersed in diesel or white oil at room temperature (25°C). It was taken out every 30 minutes, hung for 5 minutes until the surface oil phase was drained, and weighed. The measurement was stopped when the mass (m2) no longer changed. The saturated oil absorption rate (Q) of the polymer was obtained. The results are shown in Table 1, and the calculation formula is shown in Equation (1):

[0070] Q=(m2-m1) / m1×100% (1)

[0071] Table 1. Test results of oil absorption performance of different samples

[0072]

[0073]

[0074] As can be seen from Table 1, the saturated oil absorption rate of Examples 1 to 5 provided by the present invention is significantly higher than that of the comparative example. This is because the composite gel network formed by segmented photo-initiated polymerization provides more oil phase adsorption sites, which has a better adsorption and swelling effect on oil-based drilling fluids.

[0075] Experiment Example 2

[0076] Cement grout was prepared according to GB / T 19139-2012 standard, and its interfacial bonding strength performance was tested.

[0077] Cement slurry formula 1: 100g Jiahua G-grade oil well cement + 3g cementing interface reinforcement material + 4g fluid loss reducer BXF-200L(AF) + 0.2g retarder BXR-200L + 41g fresh water + 0.5g defoamer G603.

[0078] Cement slurry formula 2: 100g of Jiahua G-grade oil well cement + 4g of fluid loss reducer BXF-200L(AF) + 0.2g of retarder BXR-200L + 41g of fresh water + 0.5g of defoamer G603.

[0079] A shale core sample measuring 25mm × 50mm was soaked in oil-based drilling fluid for 1 hour, then removed and allowed to stand until the oil-based drilling fluid on the surface had drained and the core weight no longer changed. The core was then placed in a test steel sleeve, and cement slurry was added to the annular space between the core and the sleeve. The core was cured under normal pressure and an 80℃ water bath. After curing to the specified age, the core was ejected using a compressive strength testing machine to obtain the interfacial shear bond strength value. (See schematic diagram). Figure 1 The results are shown in Table 2.

[0080] Table 2 Test results of cement stone interface bonding strength performance

[0081]

[0082] As shown in Table 2, the addition of the interface reinforcement material for cementing prepared in this invention can significantly improve the interfacial bonding quality between the cement sheath and the well wall under oil-based drilling fluid. Compared with the cement stone interface bonding strength of clean slurry, it can be increased by 3 to 5 times, ensuring that the cement slurry can still have a certain sealing strength when it is invaded by oil, and providing a strong guarantee for the cementing quality under complex well conditions.

[0083] Figures 2(A) and 2(B) are scanning electron microscope images of the interface between the above-mentioned cement paste cement stone and the cement stone with added interface reinforcement material (Example 5) and the core. It can be seen that the hydration process of the cement paste slows down after encountering oil, and the structure formed at the interface is loose and porous with more amorphous CSH (hydrated calcium silicate) gel. However, the structure formed at the interface after adding interface reinforcement material is dense and uniform, which can effectively improve the interface sealing ability and improve the cementing quality.

[0084] Experimental Example 3

[0085] Cement slurry was prepared according to GB / T 19139-2012 standard, cured under normal pressure and 80℃ water bath conditions, and the compressive strength of cement stone was tested.

[0086] Cement slurry formula 1: 100g Jiahua G-grade oil well cement + 3g cementing interface reinforcement material + 4g fluid loss reducer BXF-200L(AF) + 0.2g retarder BXR-200L + 41g fresh water + 0.5g defoamer G603.

[0087] Cement slurry formula 2: 100g of Jiahua G-grade oil well cement + 4g of fluid loss reducer BXF-200L(AF) + 0.2g of retarder BXR-200L + 41g of fresh water + 0.5g of defoamer G603.

[0088] Table 3. Test results of compressive strength of cement stone

[0089]

[0090] As shown in Table 3, the addition of the interface reinforcement material for cementing prepared in this invention will reduce the compressive strength of the cement stone to some extent. However, this effect can be reduced by adjusting the ratio of styrene-based monomers and acrylate monomers in the macromolecular microspheres, as well as the amount of crosslinking agent and the UV initiation time. In the ratio of styrene-based monomers to acrylate monomers, increasing the proportion of styrene-based monomers will improve the rigidity of the polymer and reduce its impact on the mechanical properties of the cement stone. At the same time, increasing the amount of crosslinking agent and increasing the UV initiation time will increase the degree of crosslinking of the system, thereby improving the mechanical strength of the material. This allows the cement slurry to meet the cementing construction requirements while taking into account its oil absorption performance, achieving a balance between oil intrusion resistance and mechanical properties (i.e., the compressive strength of the cement stone can be appropriately sacrificed while significantly improving the interfacial bonding strength, but the construction requirements must be met).

[0091] In summary, the interface reinforcement material for cementing prepared in this invention, as a novel cement slurry additive, can effectively adsorb and disperse the oil phase when residual oil-based drilling fluid at the interface is difficult to clean by the pre-flush fluid. This improves the interfacial bonding strength between the cement sheath and the casing and wellbore, reduces the probability of oil, gas, and water channeling, and enhances cementing quality. The above embodiments only illustrate several implementation methods of this invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this invention, and these all fall within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

Claims

1. An interface reinforcing material for cementing, characterized by, The preparation materials include the following parts by weight: 100 parts styrene monomers, 30-50 parts acrylate monomers, 5-10 parts graphene oxide, 3-5 parts silane coupling agent, 3-5 parts anionic monomers, 3-5 parts cationic monomers, 3-5 parts sterically hindered crosslinking agent, 0.5-1.5 parts photoinitiator, and 200-300 parts deionized water; The silane coupling agent is vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, or γ-(methacryloyloxy)propyltrimethoxysilane; The sterically hindered crosslinking agent is ethylene glycol dicyclopentenyl ether acrylate, ethylene glycol dicyclopentenyl ether methacrylate, or pentaerythritol triacrylate. The anionic monomer is 2-acrylamide-2-methylpropanesulfonate, sodium p-styrenesulfonate, or 2-methacryloyloxyethanesulfonate. The cationic monomer is diallyl dimethyl ammonium chloride, diallyl diethyl ammonium chloride, or (3-acrylamidopropyl)trimethyl ammonium chloride; The styrene monomer is styrene, methylstyrene, or tert-butylstyrene; The acrylate monomers are methyl acrylate, butyl acrylate, octadecyl acrylate, dodecyl methacrylate, or isooctyl methacrylate; The preparation method of the cementing interface reinforcement material includes the following steps: A suitable amount of silane coupling agent is uniformly dispersed in anhydrous ethanol to obtain a silane coupling agent solution. Graphene oxide is dispersed in the silane coupling agent solution, stirred at a preset temperature for a period of time, centrifuged, washed, separated again, and dried to obtain modified graphene oxide. Take 0.5 to 1.5 parts of photoinitiator and disperse it evenly in 5 to 15 parts of deionized water to obtain a photoinitiator solution; According to the weight proportions of each component, styrene-based monomers, acrylate monomers, anionic monomers, cationic monomers, sterically hindered crosslinking agents, photoinitiator solutions, and deionized water are added to a reactor under light-protected conditions. After stirring and dissolving, ultraviolet light is used to initiate the reaction for a first preset time under a nitrogen atmosphere to obtain an aqueous solution of macromolecular microspheres. After cooling to room temperature, modified graphene oxide is added to the above aqueous solution of macromolecular microspheres. After stirring and mixing, ultraviolet light is used to initiate the reaction for a second preset time under a nitrogen atmosphere to obtain a composite polymer hydrogel. After drying, pulverizing, and sieving, an interface reinforcement material for cementing can be obtained.

2. The interface reinforcing material for use in well cementing according to claim 1, characterized in that, The photoinitiator is benzoin dimethyl ether, diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride, or 2,2-diethoxyacetophenone.

3. A method of preparing an interface reinforcing material for cementing as claimed in any one of the preceding claims 1-2, characterized by, Includes the following steps: A suitable amount of silane coupling agent is uniformly dispersed in anhydrous ethanol to obtain a silane coupling agent solution. Graphene oxide is dispersed in the silane coupling agent solution, stirred at a preset temperature for a period of time, centrifuged, washed, separated again, and dried to obtain modified graphene oxide. Take 0.5 to 1.5 parts of photoinitiator and disperse it evenly in 5 to 15 parts of deionized water to obtain a photoinitiator solution; According to the weight proportions of each component, styrene-based monomers, acrylate monomers, anionic monomers, cationic monomers, sterically hindered crosslinking agents, photoinitiator solutions, and deionized water are added to a reactor under light-protected conditions. After stirring and dissolving, ultraviolet light is used to initiate the reaction for a first preset time under a nitrogen atmosphere to obtain an aqueous solution of macromolecular microspheres. After cooling to room temperature, modified graphene oxide is added to the above aqueous solution of macromolecular microspheres. After stirring and mixing, ultraviolet light is used to initiate the reaction for a second preset time under a nitrogen atmosphere to obtain a composite polymer hydrogel. After drying, pulverizing, and sieving, an interface reinforcement material for cementing can be obtained.

4. The method of preparing an interfacial reinforcement material for use in well cementing according to claim 3, characterized in that, The first preset duration is 0.5-3h; the second preset duration is 0.5-2h.

Images