Modified cementing slurry and its preparation method and application

Abstract

The present invention relates to a modified cementing slurry, its preparation method and application. The modified cementing slurry comprises cement and a modified resin emulsion that can be cured as a single component; wherein the modified resin emulsion is an emulsion modified by a silicone-based high-temperature resistant resin demulsification; the mass of the modified resin emulsion accounts for 2 to 10% of the mass of the cement. The technical problem to be solved by the present invention is how to provide a modified cementing slurry that does not require the use of a batch mixing skid for the two-component blending of resin and curing agent during on-site construction, and the construction operation is simple; and the use of the modified cementing slurry for cementing can not only improve the bonding strength between the cement stone and the two interfaces, but also has a low material cost due to its small addition amount, which is more conducive to market promotion.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas well cementing, and in particular relates to a modified cementing slurry and a preparation method and application thereof. Background Art

[0002] During oil and gas well exploration and development, annular pressure is a common challenge faced by the global oil industry. If improperly controlled, it can easily compromise wellhead safety, shorten the life of the well, and be difficult and expensive to manage. Extensive research on cement sheath integrity has been conducted, and analysis suggests that the primary cause of pressure in the B and C annuli is the inherent brittleness and volume shrinkage of oil well cement, which is susceptible to plastic deformation and tensile failure under complex downhole stresses, leading to a loss of wellbore seal integrity. The comprehensive anti-channeling performance of the cement slurry system is a key factor influencing the long-term sealing performance of the cement sheath. Existing techniques typically improve this performance by introducing polymer emulsions into the cement slurry system.

[0003] Halliburton has developed a resin called WellLock for isolating cement slurry from cementing fluid during cementing, thereby improving the bond between the cement sheath, casing, and formation. However, its overall performance is poor, making it insufficient to replace cement slurry in cementing operations. Furthermore, the product's high cost hinders widespread adoption. Research has also examined epoxy resins, demonstrating that their addition to cement slurry can effectively improve the performance of cement systems used in oil and gas well cementing. Epoxy resin emulsions can be used for cementing alone or added to cement slurries to enhance the compressive and bonding strengths of the cement paste, improving cementing quality. However, epoxy resins are two-component products, requiring pre-mixing of the resin and curing agent for field application. This mixed solution must then be added to the cement slurry, requiring a separate batch mixing skid, making field operations complex. Furthermore, to maintain the slurry's bond strength, 30-60 wt% of the resin emulsion must be added to the slurry system, resulting in a high unit cost for the resin slurry, hindering widespread adoption. Some people have also conducted research on silicone resin. Although it can achieve single-component curing of resin cement slurry, it is sensitive to the water quality of the application environment, resulting in its obvious high-temperature thickening and the difficulty in adjusting the comprehensive performance of the cement slurry. In addition, its improvement in the bonding strength of cement stone is limited, and a higher proportion of resin is often required to achieve the required bonding strength. The unit cost is high, and it is difficult to meet the use needs of oil field cementing. Summary of the Invention

[0004] The main purpose of the present invention is to provide a modified cementing slurry and its preparation method and application. The technical problem to be solved is how to provide a modified cementing slurry so that it does not need to use a batch mixing skid to mix the two components of resin and curing agent during on-site construction, and the construction operation is simple; moreover, the use of the modified cementing slurry of the present invention for cementing can not only improve the bonding strength between the cement stone and the two interfaces, but also because its addition amount is small, the material cost is low, which is more conducive to market promotion.

[0005] The objectives and technical problems solved by the present invention are achieved by the following technical solutions. A modified cementing slurry according to the present invention comprises cement and a single-component curable modified resin emulsion; the modified resin emulsion is a silicone-based high-temperature resistant resin demulsification modified emulsion; the mass of the modified resin emulsion accounts for 2 to 10% of the mass of the cement.

[0006] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0007] Preferably, the modified cementing slurry mentioned above, wherein the modified resin emulsion is ATE-22L, has the following performance indicators: density: 1.20±0.02g.cm 3 , solid content ≥60%, PH value: 6-8, viscosity: 2500-3500mpa.s.

[0008] Preferably, the aforementioned modified cementing slurry comprises, in parts by mass: 100 parts of grade G cement, 0-110 parts of iron ore powder, 0-5 parts of microsilica, 0-5 parts of fluid loss additive, 0-5 parts of dispersant, 0-10 parts of industrial salt, 2-10 parts of modified resin emulsion, 0-1.0 parts of retarder, 0-0.2 parts of defoamer, and 40-60 parts of tap water.

[0009] Preferably, the aforementioned modified cementing slurry comprises 2-6 parts of the modified resin emulsion.

[0010] Preferably, the aforementioned modified cementing cement slurry, wherein the modified cementing cement slurry is a brine high-density cement slurry system; calculated by mass, it includes: 100 parts of G-grade cement, 70-110 parts of iron ore powder, 0-5 parts of microsilica, 0-5 parts of fluid loss additive, 0.5-5 parts of dispersant, 7-10 parts of industrial salt, 2-6 parts of modified resin emulsion, 0.1-1.0 parts of retarder, 0.1-0.2 parts of defoaming agent, and 40-60 parts of tap water.

[0011] Preferably, the aforementioned modified cementing cement slurry, wherein the modified cementing cement slurry is a freshwater conventional density cement slurry system; calculated by mass, it comprises: 100 parts of G-grade cement, 2-5 parts of microsilica, 2-5 parts of fluid loss additive, 0.5-5 parts of dispersant, 2-6 parts of modified resin emulsion, 0.1-1.0 parts of retarder, 0.1-0.2 parts of defoamer, and 40-60 parts of tap water.

[0012] Preferably, the aforementioned modified cementing slurry, wherein the iron ore powder is magnetite powder, with a density of 5.05 g / cm 3 , particle size 120 mesh; the microsilica is silicon dioxide powder with a purity of ≥98%, and the particle size of the silicon dioxide powder is 0.1μm-0.3μm; the fluid loss additive is a copolymer of sodium polyacrylate and 2-acrylamido-2-methylpropanesulfonic acid; the dispersant is a condensate of aliphatic hydroxysulfonate; the industrial salt is sodium chloride salt; the retarder is a 2-acrylamido-2-methylpropanesulfonic acid polymer; and the defoaming agent is tributyl phosphate.

[0013] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions. According to the present invention, a method for preparing the modified cementing slurry is characterized in that it includes the following steps:

[0014] Measure the G-grade cement, iron ore powder and microsilica according to the formula, mix them evenly, and obtain a dry mix material;

[0015] Measure industrial salt and water according to the formula, dissolve the industrial salt in the water to obtain mixing water; if the formula does not include industrial salt, use water as mixing water;

[0016] Adding the formulated amount of fluid loss additive, modified resin emulsion, dispersant, retarder and defoamer to the mixing water, stirring evenly to obtain a wet mixed material;

[0017] The wet mixed material is stirred at a low speed, the dry mixed material is added to the wet mixed material under stirring, the mixed material is stirred evenly at a high speed, and finally the mixed material is stirred at a variable speed to defoam the mixed material to obtain a modified cementing slurry.

[0018] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0019] Preferably, in the aforementioned preparation method, the stirring speed of the low speed gear is 3000-5000 r / min; the stirring speed of the high speed gear is 10000-14000 r / min; and the stirring speed of the variable speed gear is adjusted according to the conditions of the mixture.

[0020] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions: According to the present invention, a modified cementing slurry is used in cementing shale gas wells, tight oil wells and rock salt layer oil and gas wells.

[0021] By means of the above technical solution, the modified cementing slurry and its preparation method and application proposed in the present invention have at least the following advantages:

[0022] The modified cementing slurry, its preparation method, and its application proposed in the present invention improve the bond strength of cementing by adding a modified resin emulsion, representing 2 to 10% by weight of the cement, to conventional cementing cement. The modified resin emulsion is a single-component curable, high-temperature-resistant silicone resin demulsified emulsion. When added to the cement slurry for cementing, it eliminates the need for a batch mixing skid to mix the resin and curing agent, simplifying the construction process. Furthermore, the modified resin emulsion offers high cost-effectiveness, achieving excellent technical results with a relatively small addition amount. Simply adding 2 to 10% of the modified resin emulsion to the cement slurry, representing only 2 to 10% by weight of the cement, significantly improves the bond strength after cementing. In the technical solution of the present invention, the amount of modified resin emulsion added to the modified cementing slurry is small, resulting in minimal cost increase in the cement slurry system, material cost savings, and superior overall performance of the cement paste. While maintaining the same conventional properties as the original cement slurry, the cement paste's bond strength is significantly enhanced, nearly 2 to 3 times greater than conventional cement, resulting in superior performance.

[0023] Furthermore, the modified cementing cement slurry of the present invention has a wide range of applications. It is applicable to cement slurries of conventional density systems of freshwater and cement slurries of high density systems of salt water, and has good applicability. The technical solution of the present invention effectively improves the bonding strength between cement stone and formation and casing through the combination of various materials without affecting other properties of cement slurry. The bonding strength value is 2 to 3 times that of ordinary cement stone. Moreover, the technical solution of the present invention significantly reduces the elastic modulus of cement stone without affecting the compressive strength of cement stone, improves the toughness of cement stone, improves the cementing quality, and ensures the integrity of wellbore sealing. At the same time, the technical solution of the present invention provides strong protection for subsequent fracturing and acidizing required for cementing, as well as other wells with pressure changes, reduces secondary remedial operations due to incomplete wellbore sealing, and reduces the risk of wellbore sealing failure due to annular pressure.

[0024] Furthermore, the technical solution of the present invention is suitable for cementing shale gas wells, tight oil wells and rock salt layers. It addresses the cementing difficulties of high-pressure salt layers, high density and narrow density windows in the 244.5mm technical casing cementing in the Halfaya Oilfield in Iraq. By modifying the brine high-density cement slurry system with resin emulsion, the bonding strength between the cement sheath and the formation and casing is improved, thereby improving the overall cementing quality of the block, eliminating the occurrence of wellhead pressure, and laying the foundation for obtaining more workload for the project.

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention. DETAILED DESCRIPTION

[0026] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, the following describes in detail, in conjunction with preferred embodiments, a modified well cementing slurry, its preparation method, and its application, including its specific implementation, structure, features, and effectiveness. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0027] The present invention provides a modified cementing slurry, which includes cement and a single-component curable modified resin emulsion; wherein the modified resin emulsion is an emulsion modified by demulsification of an organosilicon-based high-temperature resistant resin; the mass of the modified resin emulsion accounts for 2-10% of the mass of the cement.

[0028] The present invention utilizes an emulsion obtained by demulsification of a high-temperature-resistant silicone resin for cementing slurry modification. This allows for curing with a single component, eliminating the need for premixing with a curing agent. This approach aligns perfectly with the field application equipment requirements of conventional cement slurries that do not incorporate resin emulsions. Furthermore, the cured cement stone exhibits superior bonding strength. During the curing process of the modified cementing slurry, the modified resin emulsion does not participate in the chemical reactions within the cement slurry. Instead, the water content of the resin emulsion is consumed through the cement hydration reaction, allowing the modified resin emulsion to dry and form a film. Therefore, a dedicated curing agent is not required.

[0029] The modified resin emulsion used in the embodiment of the present invention is a product independently developed and synthesized by the applicant, and its preparation method is as follows: add silicone monomers methylethoxysilane and phenylmethoxysilane to an ethanol solvent, stir and mix, and react at 65 to 75°C for 4 to 5 hours to obtain a silicone high-temperature resistant resin; then, add nonylphenol polyoxyethylene ether to the silicone high-temperature resistant resin for demulsification to obtain the modified resin emulsion. Among them, the molar ratio of methylethoxysilane to phenylmethoxysilane is 1:0.8 to 1.5; taking the silicone high-temperature resistant resin as the standard, the addition ratio of nonylphenol polyoxyethylene ether is 10 to 20%; the demulsification reaction temperature is 50 to 60°C, and the reaction time is 2 to 3 hours. The performance indicators of the modified resin emulsion are as follows: Density: 1.20±0.02g.cm 3 , solid content ≥60%, PH value: 6-8, viscosity: 2500-3500mpa.s.

[0030] The modified resin emulsions prepared according to the aforementioned preparation method can all achieve the technical effects of the present invention. In a specific embodiment of the present invention, the specification brand of the modified resin emulsion is ATE-22L. During the specific preparation, the molar ratio of the methylethoxysilane and phenylmethoxysilane is 3:4, the reaction temperature in the first stage is 70°C, and the reaction time is 4.5 hours; in the second stage, based on the organosilicon high-temperature resistant resin, the addition ratio of nonylphenol polyoxyethylene ether is 15%; the demulsification reaction temperature is 55°C, and the reaction time is 2.5 hours. The modified resin emulsions used in the subsequent embodiments of the present invention all use the resin emulsion with the above brand ATE-22L.

[0031] In one embodiment of the present invention, the modified cementing slurry comprises, by weight, 100 parts of Grade G cement, 0-110 parts of iron ore powder, 0-5 parts of microsilica, 0-5 parts of fluid loss additive, 0-5 parts of dispersant, 0-10 parts of industrial salt, 2-10 parts of modified resin emulsion, 0-1.0 parts of retarder, 0-0.2 parts of defoamer, and 40-60 parts of tap water. The components of the technical solution described in the present invention have a wide range of applications and are suitable for both freshwater cement slurries with normal density and saltwater cement slurries with high density, demonstrating its excellent applicability.

[0032] The modified cementing cement slurry preferably includes 2-6 parts of modified resin emulsion; when the added amount of modified resin emulsion is 2% of the mass of cement, the bonding strength of the cement stone after solidification can be better, and its bonding strength is greatly improved compared with the cement stone after solidification of cement slurry without adding modified resin emulsion. Specifically, for example, in Comparative Example 1 and Example 1, the modified resin emulsion of the present invention was not added in Comparative Example 1, and its 48-hour bonding strength was only 1.58 MPa, while 2% of the modified resin emulsion of the present invention was added in Example 1, and its 48-hour bonding strength was 3.08 MPa, and its bonding strength was increased to 1.95 times; similarly, from the comparison between Comparative Example 1 and Example 3, it can be seen that 5% of the modified resin emulsion of the present invention was added in Example 3, and its 48-hour bonding strength was 4.88 MPa, and its bonding strength was increased to 3.09 times; and when the addition amount of the modified resin emulsion was further increased to 6%, such as in Example 4, 6% of the modified resin emulsion of the present invention was added in Example 4, and its 48-hour bonding strength was 4.81 MPa, and its bonding strength was increased to 3.04 times. From the above description and the test data of the examples, it can be seen that the amount of modified resin emulsion added should not exceed 6%, and more preferably not exceed 5%; if the amount of modified resin emulsion added is too large, the increase in bonding strength is not obvious, but the viscosity of the cement slurry is increased. On the one hand, the construction risk increases, and on the other hand, adding more modified resin emulsion will also lead to an increase in the cost of the cement slurry system, which is not conducive to on-site application.

[0033] The modified cementing slurry of the present invention is suitable for preparing a brine high-density cement slurry system. The modified cementing slurry comprises, by weight, 100 parts of G-grade cement, 70-110 parts of iron ore powder, 0-5 parts of microsilica, 0-5 parts of a fluid loss additive, 0.5-5 parts of a dispersant, 7-10 parts of industrial salt, 2-6 parts of a modified resin emulsion, 0.1-1.0 parts of a retarder, 0.1-0.2 parts of a defoamer, and 40-60 parts of tap water. The performance indicators of the modified cementing slurry are shown in Table 1. The 100 Bc thickening time in the table refers to the time required for the water and cement to reach a consistency of 100 Bc after mixing.

[0034] Table 1 Performance requirements of resin brine high-density cement slurry system

[0035]

[0036]

[0037] The modified cementing slurry of the present invention is suitable for preparing a freshwater conventional density cement slurry system. Specifically, the modified cementing slurry comprises, by weight, 100 parts of G-grade cement, 2-5 parts of microsilica, 2-5 parts of fluid loss additive, 0.5-5 parts of dispersant, 2-6 parts of modified resin emulsion, 0.1-1.0 parts of retarder, 0.1-0.2 parts of defoamer, and 40-60 parts of tap water. The performance indicators of the modified cementing slurry are shown in Table 2. The 100 Bc thickening time in the table refers to the time required for the water and cement to reach a consistency of 100 Bc after mixing.

[0038] Table 2 Performance requirements of resin freshwater conventional density cement slurry system

[0039] project Performance indicators <![CDATA[Density, g / cm 3 > 1.90 Fluidity, cm 21-23 API water loss, ml (80℃, 6.9MPa, 30min) ≤50 Free fluid, % ≤0.8 <![CDATA[BP sedimentation density difference, g / cm 3 > ≤0.03 Initial consistency, Bc ≤30 100Bc thickening time (80℃), min 180-300 24-hour compressive strength (80℃), MPa ≥21.0 24-hour bonding strength (80℃), MPa ≥2.5

[0040] In order to make the cement slurry have better performance, the preferred iron ore powder in the present invention is magnetite powder with a density of 5.05 g / cm 3 , particle size 120 mesh; microsilica is preferably silicon dioxide powder with a purity of ≥98%, and the particle size of the silicon dioxide powder is 0.1 μm-0.3 μm; the preferred fluid loss additive is a copolymer of sodium polyacrylate and 2-acrylamido-2-methylpropanesulfonic acid; the preferred dispersant is a condensate of aliphatic hydroxysulfonate; the preferred industrial salt is sodium chloride; the preferred retarder is 2-acrylamido-2-methylpropanesulfonic acid polymer; and the preferred defoaming agent is tributyl phosphate. Unless otherwise specified, the raw materials used in the subsequent examples and comparative examples are the same as those defined above.

[0041] The present invention also proposes a preparation method of the aforementioned modified cementing slurry, which includes the following steps: measuring G-grade cement, iron ore powder and microsilica according to a formula, mixing them evenly to obtain a dry mixed material; measuring industrial salt and water according to a formula, dissolving the industrial salt in the water to obtain mixing water; if the formula does not include industrial salt, using water as the mixing water; adding a formulated amount of a fluid loss additive, a modified resin emulsion, a dispersant, a retarder and a defoaming agent to the mixing water, stirring evenly to obtain a wet mixed material; stirring the wet mixed material at a low speed, adding the dry mixed material to the wet mixed material under stirring, stirring the mixture evenly at a high speed, and finally stirring the mixture at a variable speed to defoam the mixture to obtain a modified cementing slurry.

[0042] In the above preparation method, the stirring speed of the low speed gear is preferably 3000-5000 r / min; the stirring speed of the high speed gear is preferably 10000-14000 r / min; and the stirring speed of the variable speed gear is adjusted according to the conditions of the mixture.

[0043] In one embodiment of the present invention, the stirring instrument used to prepare the modified cementing slurry includes three speed gears, namely low speed gear (4000r / min), high speed gear (12000r / min) and variable speed gear. The variable speed gear here means that the speed of the gear can be adjusted automatically. In order to have a better defoaming effect, stirring is generally carried out at a lower speed controlled in the variable speed gear.

[0044] The present invention also proposes the use of the aforementioned modified cementing slurry in cementing shale gas wells, tight oil wells, and rock salt formation oil and gas wells. The technical solution of the present invention is suitable for cementing shale gas wells, tight oil wells, and rock salt formations. To address the cementing challenges of high-pressure salt layers, high density, and a narrow density window in 244.5mm technical casing cementing in Iraq's Halfaya Oilfield, a resin emulsion high-density brine high-density cement slurry system was promptly developed. This system improves the bond strength between the cement sheath, the formation, and the casing, enhancing the overall cementing quality in the block and preventing wellhead pressure buildup, laying the foundation for securing more work for the project.

[0045] The present invention will be further described below with reference to specific embodiments, but this should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0046] Unless otherwise specified, the materials and reagents mentioned below are commercially available products familiar to those skilled in the art. Unless otherwise specified, the methods described are all well-known methods in the art. Unless otherwise defined, technical or scientific terms used shall have the same meanings as those commonly understood by those skilled in the art.

[0047] Example 1

[0048] Weigh 100 parts of oil well G-grade cement, 85 parts of iron ore powder, and 4 parts of microsilica, mix and stir evenly to produce a dry mix. Weigh 7.5 parts of industrial salt and dissolve them in 53 parts of tap water. Once the industrial salt is fully dissolved in the water, add 4 parts of fluid loss additive, 2 parts of modified resin emulsion, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer and stir evenly to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir again at 12000 r / min for 35 seconds. Finally, change the speed to remove foam and produce a resin-salt high-density cement slurry. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 3.

[0049] Example 2

[0050] Weigh 100 parts of oil well G-grade cement, 85 parts of iron ore powder, and 4 parts of microsilica, mix and stir evenly to produce a dry mix. Weigh 7.5 parts of industrial salt and dissolve them in 52 parts of tap water. Once the industrial salt is fully dissolved in the water, add 4 parts of fluid loss additive, 4 parts of modified resin emulsion, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer and stir evenly to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir again at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin-salt high-density cement slurry. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 3.

[0051] Example 3

[0052] Weigh 100 parts of oil well G-grade cement, 85 parts of iron ore powder, and 4 parts of microsilica, mix and stir to produce a dry mix. Weigh 7.5 parts of industrial salt and dissolve them in 51 parts of tap water. Once the industrial salt is fully dissolved in the water, add 4 parts of fluid loss additive, 2 parts of modified resin emulsion, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer to produce a wet mix. Stir the wet mix at 4000 rpm. While stirring, add the dry mix to the wet mix at a uniform speed. Stir at 12000 rpm for 35 seconds, then change the speed to remove foam to produce a resin-salt high-density cement slurry. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 3.

[0053] Example 4

[0054] Weigh 100 parts of oil well G-grade cement, 85 parts of iron ore powder, and 4 parts of microsilica, mix and stir to produce a dry mix. Weigh 7.5 parts of industrial salt and dissolve them in 50 parts of tap water. Once the industrial salt is fully dissolved in the water, add 4 parts of fluid loss additive, 6 parts of modified resin emulsion, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin-salt high-density cement slurry. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 3.

[0055] Example 5

[0056] Weigh 100 parts of oil well G-grade cement, 95 parts of iron ore powder, and 4 parts of microsilica, mix and stir to produce a dry mix. Weigh 7.5 parts of industrial salt and dissolve them in 50 parts of tap water. Once the industrial salt is fully dissolved in the water, add 4 parts of fluid loss additive, 5 parts of modified resin emulsion, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer and stir to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin-salt high-density cement slurry. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 3.

[0057] Example 6

[0058] Weigh 100 parts of oil well G-grade cement, 110 parts of iron ore powder, and 4 parts of microsilica, mix and stir to produce a dry mix. Weigh 7.5 parts of industrial salt and dissolve them in 52 parts of tap water. Once the industrial salt is fully dissolved in the water, add 4 parts of fluid loss additive, 5 parts of modified resin emulsion, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin-salt high-density cement slurry. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 3.

[0059] Comparative Example 1

[0060] Weigh 100 parts of oil well G-grade cement, 85 parts of iron ore powder, and 4 parts of microsilica, mix and stir to produce a dry mix. Weigh 7.5 parts of industrial salt and dissolve them in 50 parts of tap water. Once the industrial salt is fully dissolved in the water, add 4 parts of fluid loss additive, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer and stir to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin-salt high-density cement slurry. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 3.

[0061] Comparative Example 2

[0062] Weigh 100 parts of oil well G-grade cement, 85 parts of iron ore powder, and 4 parts of microsilica, and mix and stir to make a dry mix. Weigh 7.5 parts of industrial salt and dissolve them in 50 parts of tap water. Once the industrial salt is fully dissolved in the water, add 4 parts of fluid loss additive, 5 parts of silicone resin emulsion from another oilfield manufacturer (due to limited research on single-component curable silicone resin emulsions, only one standard reference product with unknown composition is available in the oilfield; this raw material is used as a control in all the following comparative examples), 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer, and stir to make a wet mix. Stir the wet mix at 4000 rpm. While stirring, add the dry mix to the wet mix at a uniform speed. Stir at 12000 rpm for 35 seconds, then change the speed to remove foam, to obtain a resin-salt high-density cement slurry. The performance indicators of the modified cementing slurry according to the present invention are shown in Table 3.

[0063] Table 3 Properties of resin brine high density cement slurry system

[0064]

[0065]

[0066] Note: The above columns represent the following indicators: A is density, unit is g / cm 3 ; B is fluidity, unit is cm, the smaller the number, the worse the fluidity; C is BP sedimentation density difference g / cm 3 ; D is API water loss in ml; E is free liquid content, in %; F is initial consistency, in Bc; G is thickening time, in 100 Bc / min; H is 48-hour compressive strength, in MPa; I is 48-hour bonding strength, in MPa.

[0067] Examples 1 to 6 and Comparative Examples 1 and 2 are brine high-density cement slurry systems. The test data from the examples and comparative examples show that the addition of the modified resin emulsion to the cement slurry system significantly increases the cement slurry's bond strength; compared to the cement slurry without the modified resin emulsion, the bond strength is increased by 2 to 3 times. This significant increase in bond strength is beneficial to the development of bond strength between the cement sheath and the two interfaces, improving cementing quality. However, the test data from the examples and comparative examples also show that the addition of too much modified resin emulsion should not be too large, as increasing the amount of modified resin emulsion does not significantly increase its bond strength. Instead, it may increase the viscosity of the cement slurry, leading to increased construction risks and increased material costs for the cement slurry, hindering on-site application and promotion.

[0068] It can be seen from the test data of Comparative Example 2 that although replacing the organic silicon resin emulsion of other oil field manufacturers can also have a certain effect of improving the bonding strength, its improvement effect on bonding strength cannot achieve the modification effect of the modified cementing cement slurry of the present invention; Specifically, Example 3 and Comparative Example 2 have the same basic formula, both adding 5% organic silicon resin emulsion, and the only difference is the specifications of the organic silicon resin. The bonding strength of the cement stone in Comparative Example 2 is 3.16MPa, while the bonding strength of the cement stone in Example 3 is 4.88MPa. It can be seen that the present invention has a better bonding strength than the conventional cementing cement slurry. Compared with the prior art, the technical solution of the present invention improves the 48-hour bonding strength by 54%. Moreover, the modified cementing cement slurry of the present invention only needs to add a small amount of modified resin emulsion to achieve the bonding strength when a larger amount of silicone resin emulsion is added from other manufacturers. For example, the basic formulas of Example 1 and Comparative Example 2 are basically the same. Only 2% of the modified resin emulsion is added in Example 1 to achieve a bonding strength that is basically equivalent to that of Comparative Example 2 with 5% silicone resin emulsion (3.08 MPa in the former and 3.16 MPa in the latter), which greatly saves material costs.

[0069] Example 7

[0070] Weigh 100 parts of oil well G-grade cement and 3 parts of microsilica, mix and stir evenly to produce a dry mix. Weigh 38 parts of tap water, add 3 parts of fluid loss additive, 6 parts of modified resin emulsion, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer, and stir evenly to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir again at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin freshwater cement slurry of normal density. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 4.

[0071] Example 8

[0072] Weigh 100 parts of oil well G-grade cement and 3 parts of microsilica, mix and stir evenly to produce a dry mix. Weigh 40 parts of tap water, add 4 parts of fluid loss additive, 3 parts of modified resin emulsion, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer, and stir evenly to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir again at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin freshwater cement slurry of normal density. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 4.

[0073] Comparative Example 3

[0074] Weigh 100 parts of oil well G-grade cement and 3 parts of microsilica, mix and stir evenly to produce a dry mix. Weigh 42 parts of tap water, add 4 parts of fluid loss additive, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer, and stir evenly to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir again at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin freshwater cement slurry of normal density. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 4.

[0075] Comparative Example 4

[0076] Weigh 100 parts of oil well G-grade cement and 3 parts of microsilica, mix and stir evenly to produce a dry mix. Weigh 40 parts of tap water, add 4 parts of fluid loss additive, 3 parts of silicone resin emulsion from another oilfield manufacturer, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer, and stir evenly to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir again at 12000 r / min for 35 seconds, then change the speed to remove foam to produce a resin freshwater cement slurry of normal density. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 4.

[0077] Comparative Example 5

[0078] Weigh 100 parts of oil well G-grade cement and 3 parts of microsilica, mix and stir evenly to produce a dry mix. Weigh 38 parts of tap water, add 3 parts of fluid loss additive, 6 parts of silicone resin emulsion from another oilfield manufacturer, 1 part of dispersant, 0.2 parts of retarder, and 0.2 parts of defoamer, and stir evenly to produce a wet mix. Stir the wet mix at 4000 r / min. While stirring, add the dry mix to the wet mix at a uniform speed. Stir again at 12000 r / min for 35 seconds, then change the speed to remove foam, to produce a resin freshwater cement slurry of normal density. Testing shows the performance indicators of the modified cementing slurry according to the present invention, as shown in Table 4.

[0079] Table 4 Properties of resin freshwater conventional density cement slurry system

[0080] A B C D E F G H I Example 7 1.90 21 0.01 40 0 28 209 26.2 4.68 Example 8 1.90 22 0.01 38 0 21 195 26.8 4.66 Comparative Example 3 1.90 22 0.02 42 0 18 190 22.4 1.58 Comparative Example 4 1.90 22 0.01 44 0 21 185 25.6 2.45 Comparative Example 5 1.90 20 0.01 42 0 32 200 26.3 3.88

[0081] Note: The above columns represent the following indicators: A is density, unit is g / cm 3; B is fluidity, unit is cm, the smaller the number, the worse the fluidity; C is BP sedimentation density difference, unit is g / cm3; D is API water loss, unit is ml; E is free liquid content, unit is %; F is initial consistency, unit is Bc; G is thickening time, unit is 100Bc / min; H is 24-hour compressive strength, unit is MPa; I is 24-hour bonding strength, unit is MPa.

[0082] Examples 7 and 8 and Comparative Examples 3 to 5 are freshwater conventional density cement slurry systems. It can be seen from the test data of the examples and comparative examples that the addition of modified resin emulsion to the cement slurry system has a certain effect of reducing water loss, and significantly improves the compressive strength and bonding strength of cement stone; compared with the bonding strength of cement slurry without modified resin emulsion, it is increased to nearly 3 times; specifically, in Example 7 and Comparative Example 3, the bonding strength of Comparative Example 3 without modified resin emulsion is only 1.58Mpa, while in Example 7, 6% modified resin emulsion is added, and its bonding strength is increased to 4.68Mpa; the bonding strength is 1.58Mpa. The great improvement is beneficial to the development of the bonding strength between the cement sheath and the two interfaces, and improves the cementing quality; however, the amount of modified resin emulsion added should not be too large, because as the amount of modified resin emulsion added increases, the further increase in its bonding strength is not obvious. For example, in Example 7 and Example 8, the two phases with the addition of modified resin emulsion differ by half, but the bonding strength is basically the same; if the amount of modified resin emulsion added exceeds 6%, it may cause difficulty in cement slurry discharging, reduce the fluidity of the slurry, increase the consistency value, increase the construction risk, and be unfavorable for on-site construction operations.

[0083] By comparing Cases 4 and 5, it can be concluded that the silicone resins of other oilfield manufacturers also have a certain effect on improving the compressive strength and bonding strength of cement stone. However, at the same addition amount, the performance effect of the modified cementing cement slurry of the present invention is better. For example, the resin addition amount of Example 8 and Comparative Example 4 is both 3%, but the bonding strength of the former is as high as 4.66 MPa, while the bonding strength of the latter is as low as 2.45 MPa, a difference of nearly twice. If the same level of performance improvement is to be achieved, the amount of modified resin emulsion added in the modified cementing cement slurry of the present invention is smaller, only half or even less. For example, in Example 8 and Comparative Example 5, Example 8 only adds 3% of the modified resin emulsion, and its bonding strength is as high as 4.66 MPa, while the resin addition amount of Comparative Example 5 is as high as 6%, which is twice the amount added in Example 8, and its bonding strength is only 3.88 MPa, which is only 83% of that in Example 8. As can be seen from the above, the cement slurry of the present invention has lower unit cost and higher field application value.

[0084] The technical features in the claims and / or the specification of the present invention may be combined, and the manner of combination is not limited to the combination obtained by reference in the claims. The technical solutions obtained by combining the technical features in the claims and / or the specification are also within the scope of protection of the present invention.

[0085] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A modified cementing slurry, characterized in that: The invention relates to a single-component curable modified resin emulsion, wherein the modified resin emulsion is an emulsion modified by demulsification of an organosilicon-based high-temperature resistant resin; the mass of the modified resin emulsion accounts for 2-6% of the mass of the cement; the preparation method of the modified resin emulsion is as follows: adding organosilicon monomers methylethoxysilane and phenylmethoxysilane to an ethanol solvent, stirring and mixing, and heating to 65-75°C for reaction for 4-5 hours to obtain an organosilicon-based high-temperature resistant resin; then, adding nonylphenol polyoxyethylene ether to the organosilicon-based high-temperature resistant resin for demulsification to obtain the modified resin emulsion; wherein the molar ratio of methylethoxysilane to phenylmethoxysilane is 1:0.8-1.5; taking the organosilicon-based high-temperature resistant resin as a standard, the addition ratio of nonylphenol polyoxyethylene ether is 10-20%; the demulsification reaction temperature is 50-60°C, and the reaction time is 2-3 hours.

2. The modified cementing slurry according to claim 1, characterized in that: The performance indicators of the modified resin emulsion are as follows: Density: 1.20±0.02g / cm 3 , solid content ≥60%, PH value: 6-8, viscosity: 2500-3500mpa.s.

3. The modified cementing slurry according to claim 1, characterized in that: Calculated by mass, it includes: 100 parts of G-grade cement, 0-110 parts of iron ore powder, 0-5 parts of microsilica, 0-5 parts of fluid loss additive, 0-5 parts of dispersant, 0-10 parts of industrial salt, 2-6 parts of modified resin emulsion, 0-1.0 parts of retarder, 0-0.2 parts of defoaming agent, and 40-60 parts of tap water; the microsilica is silicon dioxide powder with a purity of ≥98%.

4. The modified cementing slurry according to claim 3, characterized in that: The modified cementing slurry is a brine high-density cement slurry system; Calculated by mass, it includes: 100 parts of G-grade cement, 70-110 parts of iron ore powder, 0-5 parts of microsilica, 0-5 parts of fluid loss additive, 0.5-5 parts of dispersant, 7-10 parts of industrial salt, 2-6 parts of modified resin emulsion, 0.1-1.0 parts of retarder, 0.1-0.2 parts of defoaming agent, and 40-60 parts of tap water.

5. The modified cementing slurry according to claim 3, characterized in that: The modified cementing slurry is a freshwater conventional density cement slurry system; calculated by mass, it includes: 100 parts of G-grade cement, 2-5 parts of microsilica, 2-5 parts of fluid loss additive, 0.5-5 parts of dispersant, 2-6 parts of modified resin emulsion, 0.1-1.0 parts of retarder, 0.1-0.2 parts of defoamer, and 40-60 parts of tap water.

6. The modified cementing slurry according to any one of claims 3 to 5, characterized in that: The iron ore powder is magnetite powder with a density of 5.05 g / cm 3 , particle size 120 mesh; the particle size of the silicon dioxide powder is 0.1μm-0.3μm; the fluid loss additive is a copolymer of sodium polyacrylate and 2-acrylamido-2-methylpropanesulfonic acid; the dispersant is an aliphatic hydroxysulfonate condensate; the industrial salt is sodium chloride; the retarder is a 2-acrylamido-2-methylpropanesulfonic acid polymer; and the defoaming agent is tributyl phosphate.

7. A method for preparing the modified cementing slurry according to any one of claims 3 to 6, characterized in that: It includes the following steps: Measure the G-grade cement, iron ore powder and microsilica according to the formula, mix them evenly, and obtain a dry mix material; Measure industrial salt and water according to the formula, dissolve the industrial salt in the water to obtain mixing water; if the formula does not include industrial salt, use water as mixing water; Adding the formulated amount of fluid loss additive, modified resin emulsion, dispersant, retarder and defoamer to the mixing water, stirring evenly to obtain a wet mixed material; The wet mixed material is stirred at a low speed, the dry mixed material is added to the wet mixed material under stirring, the mixed material is stirred evenly at a high speed, and finally the mixed material is stirred at a variable speed to defoam the mixed material to obtain a modified cementing slurry.

8. The preparation method according to claim 7, characterized in that The stirring speed of the low speed gear is 3000~5000r / min; the stirring speed of the high speed gear is 10000~14000r / min; the stirring speed of the variable speed gear is adjusted according to the conditions of the mixture.

9. Use of the modified cementing slurry according to any one of claims 1 to 6 in cementing shale gas wells, tight oil wells and rock salt layer oil and gas wells.

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