Friction and drag reducing agent as well as preparation method and application thereof

Abstract

The invention provides a friction and drag reducing agent as well as a preparation method and application thereof. The friction and drag reducing agent is prepared from the following raw materials in parts by weight: 20 to 40 parts of unsaturated polyether macromonomer, 0.1 to 0.5 part of initiator, 0.02 to 0.2 part of chain transfer agent, 2 to 4 parts of unsaturated carboxylic acid monomer, 2 to 3 parts of unsaturated polycyclic monomer, 3 to 5 parts of unsaturated phosphoric acid monomer and 120 to 175 parts of water. The friction-reducing and drag-reducing agent provided by the invention is wide in applicable temperature range, and can effectively improve the flowability, temperature resistance and salt resistance of a cement slurry system and reduce the friction-resistance coefficient.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas well cementing technology, specifically relating to a friction-reducing and drag-reducing agent, its preparation method, and its application. Background Technology

[0002] Deep and ultra-deep oil and gas reservoirs have become important alternative energy sources for China's oil and gas industry, with exploration and development progressing from 6000m and ultra-deep wells to 8000m and 9000m depths. As well depth increases, the complexity of geology, operating conditions, and wellbore structure also increases. Under deep and long cementing sections, cementing operations face challenges such as high annular friction and high pump pressure, leading to increased downhole leakage risks. Cement slurry is the foundation of cementing operations, but as a high-concentration solid (cement particle) suspension dispersion system, it has high viscosity and shear stress, making turbulent displacement difficult to achieve during cementing. Drag-reducing agents can lower the viscosity and shear stress of cement slurry, reducing internal friction between solid particles in the system. This allows for turbulent displacement of cement slurry at lower flow rates or even higher turbulence at the same flow rate, improving displacement efficiency and cementing quality. This is crucial for improving cementing operation efficiency and ensuring safety.

[0003] CN112300323A discloses a drag-reducing and viscosity-reducing agent for oil well cement and its preparation method. The preparation method includes: mixing 40-60 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid, 5-15 parts by weight of itaconic acid, 10-20 parts by weight of acrylic acid, 10-25 parts by weight of dimethyl diallyl ammonium chloride, and 3-10 parts by weight of a hydrophobic monomer at a pH... The mixture is prepared by mixing under conditions of 5-7. A chain transfer agent is added to the mixture, and then an initiator is added under nitrogen protection at a temperature of 55-85°C to carry out a polymerization reaction to obtain an amphoteric polymer. A polycarboxylate drag reducer and an alkanolamine coagulant are obtained. The amphoteric polymer, the polycarboxylate drag reducer and the alkanolamine coagulant are mixed at a weight ratio of (4.5-5.5):(2.5-3.5):1 to obtain a drag reducer and viscosity reducer for oil well cement. The drag reducer and viscosity reducer provided by this technical solution can significantly reduce the viscosity and rheological properties of cement slurry systems with synthetic AMPS polymers as additives.

[0004] CN111218263A discloses a novel drag-reducing agent for oil well cement. The novel drag-reducing agent for oil well cement comprises, by weight, parts of: 1-20 parts of sodium 3-allyloxy-1-hydroxy-1-propanesulfonate, 5-20 parts of acrylic acid, 1-10 parts of sodium p-styrenesulfonate, and 1-10 parts of aldehyde-ketone condensate. The novel drag-reducing agent for oil well cement provided by this technical solution can solve the rheological problems of high-density and ultra-high-density cement slurries in brine, and has good high-temperature stability. It can also solve the problems of core saturation and bulging.

[0005] Currently, although there is extensive research on drag-reducing agents for oil well cement slurries, reports on environmentally friendly drag-reducing agents with excellent friction-reducing effects are scarce, especially regarding their application in high-density cement slurry systems. High-density cement slurry systems have a high solid content, with a large volume fraction of weighting agents and other solid phases. During the circulation of high-density cement slurry, increased collisions and friction occur between various solid particles, between the solid and liquid phases, and within the liquid phase. This manifests as increased viscosity, shear force, and adhesion coefficient of the cement slurry. In the downhole, i.e., during pumping, this increases the flow resistance of the cement slurry, making pumping difficult, increasing pumping pressure, and potentially leading to cementing safety accidents. Furthermore, the significant impact of drag-reducing agents on the settling stability and strength of cement slurry under high-temperature conditions remains to be addressed.

[0006] Therefore, there is a need to develop a friction-reducing agent that is suitable for high-temperature environments and high-density cement slurry systems, is environmentally friendly, and can effectively improve the fluidity and salt resistance of cement slurry systems while reducing the friction coefficient. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a friction-reducing agent, its preparation method, and its application. The friction-reducing agent has a wide applicable temperature range and can effectively improve the fluidity, temperature resistance, and salt resistance of cement slurry systems, while reducing the coefficient of friction.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a friction-reducing and drag-reducing agent, wherein the raw materials for preparing the friction-reducing and drag-reducing agent include the following components by weight: 20-40 parts (22, 24, 26, 28, 30, 32, 34, 36, or 38 parts, etc.) of unsaturated polyether macromonomer, 0.1-0.5 parts (e.g., 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or 0.45 parts, etc.) of initiator, 0.02-0.2 parts (e.g., 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, or 0.18 parts, etc.) of chain transfer agent, and unsaturated polyether macromonomer. 2-4 parts of saturated carboxylic acid monomer (e.g., 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, or 3.8 parts, etc.), 2-3 parts of unsaturated polycyclic monomer (e.g., 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, or 2.9 parts, etc.), 3-5 parts of unsaturated phosphate monomer (e.g., 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, or 4.8 parts, etc.), and 120-175 parts of water (e.g., 130, 140, 150, 160, or 170 parts, etc.).

[0010] In this invention, the unsaturated polyether macromonomer in the friction-reducing and drag-reducing agent enhances the steric hindrance of the polymer through its long side-chain structure, improves molecular flexibility, and enhances the dispersibility between cement particles, thus improving the friction-reducing and drag-reducing effect. The addition of unsaturated carboxylic acid monomers improves the polymer's adsorption to cement particles, forming an electric double layer on the surface of the cement particles, generating electrostatic repulsion, improving the dispersibility between cement particles, and reducing the viscosity of the cement slurry. The addition of unsaturated phosphate monomers enhances the friction-reducing and drag-reducing agent's complexation ability with calcium ions and reduces its sensitivity to sulfate ions, improving the dispersion and retention ability of cement particles. Partially replacing unsaturated carboxylic acid monomers with unsaturated phosphate monomers improves the adaptability of the friction-reducing and drag-reducing agent to cement slurry. The unsaturated polycyclic monomers provide rigid and salt-resistant groups, improving thermal stability and salt resistance, and enhancing the dispersion and retention ability of cement particles. The chain transfer agent regulates the polymer molecular weight and optimizes drag-reducing performance. This invention improves the temperature resistance, salt resistance, and friction-reducing and drag-reducing performance of the friction-reducing and drag-reducing agent through optimized molecular structure design, the introduction of rigid and salt-resistant groups, synergistic effects of multifunctional groups, and molecular weight control. The friction-reducing agent has a wide applicable temperature range, from 25℃ to 240℃.

[0011] Adding the friction-reducing agent described in this invention to cement slurry can reduce the collision and friction between various solid particles, between the solid and liquid phases, and within the liquid phase. It also reduces the friction between the cement slurry and the casing and rock formations during pumping, ensuring smooth pumping under high-temperature conditions during the cement slurry circulation process. This gives the cement slurry the characteristics of "low temperature, low viscosity, and long-lasting dispersion," thereby solving the problems of high annular friction, high pump pressure, and increased downhole leakage risk during cementing operations in deep and long cementing sections.

[0012] Preferably, the unsaturated polyether macromonomer includes methyl allyl polyoxyethylene ether.

[0013] Preferably, the weight-average molecular weight of the methyl allyl polyoxyethylene ether is 2000-4000, such as 2200, 2400, 2600, 2800, 3000, 3200, 3400, 3600 or 3800.

[0014] Preferably, the initiator comprises any one or a combination of at least two of potassium persulfate, ammonium persulfate, or sodium persulfate.

[0015] Preferably, the chain transfer agent comprises any one or a combination of at least two of 3-mercaptopropionic acid, mercaptoethanol, or isopropanol.

[0016] Preferably, the unsaturated carboxylic acid monomer includes any one or a combination of at least two of acrylic acid, itaconic acid, maleic acid, or fumaric acid.

[0017] Preferably, the unsaturated polycyclic monomer comprises sodium p-styrenesulfonate and / or vinylphenylsulfonic acid.

[0018] In this invention, the unsaturated polycyclic monomer contains phenyl and sulfonic acid groups, which can provide rigid and salt-resistant groups for the friction-reducing and drag-reducing agent, thereby improving the thermal stability and salt resistance of the friction-reducing and drag-reducing agent and enhancing the dispersion and retention ability of cement particles.

[0019] Preferably, the unsaturated phosphate monomer is isopropenzyme and / or diethyl vinylphosphonate.

[0020] Preferably, the raw materials for preparing the friction-reducing and drag-reducing agent also include a pH adjuster.

[0021] Preferably, the pH adjuster comprises any one or a combination of at least two of sodium hydroxide, sodium carbonate, or potassium hydroxide.

[0022] In a second aspect, the present invention provides a method for preparing a friction-reducing and drag-reducing agent as described in the first aspect, the method comprising the following steps: mixing an unsaturated polyether macromonomer, an initiator, a chain transfer agent, an unsaturated carboxylic acid monomer, an unsaturated polycyclic monomer, an unsaturated phosphate monomer, and water, and reacting to obtain the friction-reducing and drag-reducing agent.

[0023] Preferably, the mixing further includes mixing with a pH adjuster.

[0024] Preferably, the preparation method specifically includes the following steps:

[0025] (1) Mix the unsaturated polyether macromonomer with some water to obtain a base solution.

[0026] (2) Mix the initiator, chain transfer agent and a portion of water to obtain component A.

[0027] (3) Mix unsaturated carboxylic acid monomer, unsaturated polycyclic monomer, unsaturated phosphate monomer and some water to obtain component B.

[0028] (4) Heat the base solution obtained in step (1), add component A obtained in step (2) and component B obtained in step (3), keep the reaction at the temperature, add pH adjuster and the remaining water to obtain the friction reducing agent.

[0029] Steps (1), (2), and (3) can be performed in any order or simultaneously.

[0030] Preferably, the water in step (1) is in the form of 50-70 parts by weight, such as 52, 54, 56, 58, 60, 62, 64 or 68 parts.

[0031] Preferably, the water in step (2) is in the form of 10-20 parts by weight, such as 11, 12, 13, 14, 15, 16, 17, 18 or 19 parts.

[0032] Preferably, the water in step (3) is in the form of 10-20 parts by weight, such as 11, 12, 13, 14, 15, 16, 17, 18 or 19 parts.

[0033] Preferably, the heating in step (4) is to heat to 60-80°C, such as 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C or 78°C.

[0034] Preferably, the addition of component A obtained in step (2) and component B obtained in step (3) in step (4) specifically refers to the simultaneous addition of component A obtained in step (2) and component B obtained in step (3).

[0035] Preferably, the time for adding component A in step (2) and component B in step (3) is independently 1-3h, for example 1.2h, 1.4h, 1.6h, 1.8h, 2.0h, 2.2h, 2.4h, 2.6h or 2.8h.

[0036] Preferably, the temperature of the heat preservation reaction in step (4) is 60-80℃ (e.g., 62℃, 64℃, 66℃, 68℃, 70℃, 72℃, 74℃, 76℃ or 78℃, etc.), and the time is 1-3h (e.g., 1.2h, 1.4h, 1.6h, 1.8h, 2.0h, 2.2h, 2.4h, 2.6h or 2.8h, etc.).

[0037] Preferably, the addition of pH adjuster in step (4) is to add pH adjuster to pH 6-7, such as 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8 or 6.9.

[0038] In this invention, a friction-reducing and drag-reducing agent was prepared by low-temperature synthesis and liquid-liquid dropwise addition process, using an oxidation-reduction system as an initiator. The preparation method is simple, green, safe and environmentally friendly, with mild conditions, low raw material cost and processing cost, and can be produced and promoted on a large scale.

[0039] Thirdly, the present invention provides a cement slurry comprising the friction-reducing agent as described in the first aspect.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The friction-reducing agent prepared by this invention through the compounding of unsaturated polyether macromonomers, initiators, chain transfer agents, unsaturated carboxylic acid monomers, unsaturated polycyclic monomers, and unsaturated phosphate monomers has a wide applicable temperature range of 25℃-240℃. It can effectively improve the fluidity, temperature resistance, and salt resistance of cement slurry systems, and reduce the friction coefficient. Adding the friction-reducing agent to the cement slurry system can reduce the friction coefficient by more than 20%. Detailed Implementation

[0042] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0043] The sources of some of the raw materials used in the following examples and comparative examples are as follows:

[0044] Unsaturated polyether macromonomer A

[0045] A1: Methyl allyl polyoxyethylene ether, with a weight-average molecular weight of 2000, sourced from Liaoning Aoke Chemical Co., Ltd.

[0046] A2: Methyl allyl polyoxyethylene ether, with a weight-average molecular weight of 4000, sourced from Liaoning Aoke Chemical Co., Ltd.

[0047] A3: Methyl allyl polyoxyethylene ether, with a weight-average molecular weight of 3000, sourced from Liaoning Aoke Chemical Co., Ltd.

[0048] A4: Methyl allyl polyoxyethylene ether, with a weight-average molecular weight of 1000, sourced from Liaoning Aoke Chemical Co., Ltd.

[0049] A5: Methyl allyl polyoxyethylene ether, with a weight-average molecular weight of 5000, is sourced from Liaoning Aoke Chemical Co., Ltd.

[0050] All other raw materials are ordinary commercially available products.

[0051] Example 1

[0052] This embodiment provides a friction-reducing and drag-reducing agent and its preparation method. The raw materials for preparing the friction-reducing and drag-reducing agent include the following components by weight: 20 parts of unsaturated polyether macromonomer (Al), 0.1 parts of initiator (ammonium persulfate), 0.02 parts of chain transfer agent (mercaptoethanol), 2 parts of unsaturated carboxylic acid monomer (itaconic acid), 2 parts of unsaturated polycyclic monomer (sodium p-styrenesulfonate), 3 parts of unsaturated phosphoric acid monomer (isopropenylphosphonic acid), pH adjuster (sodium hydroxide), and 172 parts of water.

[0053] The friction-reducing and drag-reducing agent was prepared using the following method:

[0054] (1) Mix 20 parts by weight of unsaturated polyether macromonomer and 50 parts by weight of water to obtain a base solution;

[0055] (2) Mix 0.1 parts by weight of initiator, 0.02 parts by weight of chain transfer agent and 10 parts by weight of water to obtain component A;

[0056] (3) Mix 2 parts by weight of unsaturated carboxylic acid monomer, 2 parts by weight of unsaturated polycyclic monomer, 3 parts by weight of unsaturated phosphate monomer and 10 parts by weight of water to obtain component B;

[0057] (4) Heat the base solution obtained in step (1) to 80°C, and simultaneously add component A obtained in step (2) and component B obtained in step (3) dropwise to the base solution at a uniform rate. The time for adding component A and component B is 1 hour. Keep the reaction at 80°C for 1 hour, then add pH adjuster to adjust pH to 6, add the remaining water, stir evenly, and obtain the friction reducing agent.

[0058] Example 2

[0059] This embodiment provides a friction-reducing and drag-reducing agent and its preparation method. The raw materials for preparing the friction-reducing and drag-reducing agent include the following components by weight: 40 parts of unsaturated polyether macromonomer (A2), 0.5 parts of initiator (ammonium persulfate), 0.2 parts of chain transfer agent (mercaptoethanol), 2 parts of unsaturated carboxylic acid monomer (itaconic acid), 2 parts of unsaturated polycyclic monomer (sodium styrene sulfonate), 3 parts of unsaturated phosphoric acid monomer (isopropenylphosphonic acid), pH adjuster (sodium hydroxide), and 150 parts of water.

[0060] The friction-reducing and drag-reducing agent was prepared using the following method:

[0061] (1) Mix 40 parts by weight of unsaturated polyether macromonomer and 70 parts by weight of water to obtain a base solution;

[0062] (2) Mix 0.5 parts by weight of initiator, 0.2 parts by weight of chain transfer agent and 20 parts by weight of water to obtain component A;

[0063] (3) Mix 2 parts by weight of unsaturated carboxylic acid monomer, 2 parts by weight of unsaturated polycyclic monomer, 3 parts by weight of unsaturated phosphate monomer and 20 parts by weight of water to obtain component B;

[0064] (4) Heat the base solution obtained in step (1) to 60°C, and simultaneously and uniformly add component A obtained in step (2) and component B obtained in step (3) to the base solution. The time for adding component A and component B is 3 hours. Keep the reaction at 60°C for 3 hours, then add pH adjuster to adjust pH to 7, add the remaining water, stir evenly, and obtain the friction reducing agent.

[0065] Example 3

[0066] This embodiment provides a friction-reducing and drag-reducing agent and its preparation method. The raw materials for preparing the friction-reducing and drag-reducing agent include the following components by weight: 30 parts of unsaturated polyether macromonomer (A3), 0.3 parts of initiator (ammonium persulfate), 0.1 parts of chain transfer agent (mercaptoethanol), 3 parts of unsaturated carboxylic acid monomer (itaconic acid), 2.5 parts of unsaturated polycyclic monomer (sodium styrene sulfonate), 4 parts of unsaturated phosphoric acid monomer (isopropenylphosphonic acid), pH adjuster (sodium hydroxide), and 158 parts of water.

[0067] The friction-reducing and drag-reducing agent was prepared using the following method:

[0068] (1) Mix 30 parts by weight of unsaturated polyether macromonomer and 60 parts by weight of water to obtain a base solution;

[0069] (2) Mix 0.3 parts by weight of initiator, 0.1 parts by weight of chain transfer agent and 15 parts by weight of water to obtain component A;

[0070] (3) Mix 3 parts by weight of unsaturated carboxylic acid monomer, 2.5 parts by weight of unsaturated polycyclic monomer, 4 parts by weight of unsaturated phosphate monomer and 15 parts by weight of water to obtain component B;

[0071] (4) Heat the base solution obtained in step (1) to 70°C, and simultaneously add component A obtained in step (2) and component B obtained in step (3) dropwise to the base solution at a uniform rate. The time for adding component A and component B is 2 hours. Keep the reaction at 70°C for 2 hours, then add pH adjuster to adjust pH to 7, add the remaining water, stir evenly, and obtain the friction reducing agent.

[0072] Example 4

[0073] This embodiment provides a friction-reducing and drag-reducing agent and its preparation method. The raw materials for preparing the friction-reducing and drag-reducing agent include the following components by weight: 30 parts of unsaturated polyether macromonomer (A3), 0.3 parts of initiator (potassium persulfate), 0.1 parts of chain transfer agent (3-mercaptopropionic acid), 3 parts of unsaturated carboxylic acid monomer (acrylic acid), 2.5 parts of unsaturated polycyclic monomer (vinylphenylsulfonic acid), 4 parts of unsaturated phosphate monomer (diethyl vinylphosphonate), pH adjuster (sodium carbonate), and 158 parts of water.

[0074] The friction-reducing and drag-reducing agent was prepared using the following method:

[0075] (1) Mix 30 parts by weight of unsaturated polyether macromonomer and 60 parts by weight of water to obtain a base solution;

[0076] (2) Mix 0.3 parts by weight of initiator, 0.1 parts by weight of chain transfer agent and 15 parts by weight of water to obtain component A;

[0077] (3) Mix 3 parts by weight of unsaturated carboxylic acid monomer, 2.5 parts by weight of unsaturated polycyclic monomer, 4 parts by weight of unsaturated phosphate monomer and 15 parts by weight of water to obtain component B;

[0078] (4) Heat the base solution obtained in step (1) to 60°C, and simultaneously and uniformly add component A obtained in step (2) and component B obtained in step (3) to the base solution. The time for adding component A and component B is 2 hours. Keep the reaction at 60°C for 2 hours, then add pH adjuster to adjust pH to 6.5, add the remaining water, stir evenly, and obtain the friction reducing agent.

[0079] Example 5

[0080] This embodiment provides a friction-reducing and drag-reducing agent and its preparation method. The raw materials for preparing the friction-reducing and drag-reducing agent include the following components by weight: 30 parts of unsaturated polyether macromonomer (A2), 0.3 parts of initiator (sodium persulfate), 0.1 parts of chain transfer agent (isopropanol), 3 parts of unsaturated carboxylic acid monomer (maleic acid), 2.5 parts of unsaturated polycyclic monomer (sodium p-styrenesulfonate), 4 parts of unsaturated phosphate monomer (diethyl vinylphosphonate), pH adjuster (potassium hydroxide), and 158 parts of water.

[0081] The friction-reducing and drag-reducing agent was prepared using the following method:

[0082] (1) Mix 30 parts by weight of unsaturated polyether macromonomer and 60 parts by weight of water to obtain a base solution;

[0083] (2) Mix 0.3 parts by weight of initiator, 0.1 parts by weight of chain transfer agent and 15 parts by weight of water to obtain component A;

[0084] (3) Mix 3 parts by weight of unsaturated carboxylic acid monomer, 2.5 parts by weight of unsaturated polycyclic monomer, 4 parts by weight of unsaturated phosphate monomer and 15 parts by weight of water to obtain component B;

[0085] (4) Heat the base solution obtained in step (1) to 60°C, and simultaneously and uniformly add component A obtained in step (2) and component B obtained in step (3) to the base solution. The time for adding component A and component B is 2 hours. Keep the reaction at 60°C for 2 hours, then add pH adjuster to adjust pH to 6, add the remaining water, stir evenly, and obtain the friction reducing agent.

[0086] Example 6

[0087] This embodiment provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this embodiment and Example 1 is that the unsaturated polyether macromonomer (A1) is replaced with the same mass of unsaturated polyether macromonomer (A4), while the other conditions are the same as in Example 1.

[0088] Example 7

[0089] This embodiment provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this embodiment and Example 1 is that the unsaturated polyether macromonomer (A1) is replaced with the same mass of unsaturated polyether macromonomer (A5), while the other conditions are the same as in Example 1.

[0090] Comparative Example 1

[0091] This comparative example provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this example and Example 1 is that the weight of the unsaturated polycyclic monomer (sodium styrene sulfonate) is adjusted to 1 part, while the other conditions are the same as in Example 1.

[0092] Comparative Example 2

[0093] This comparative example provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this example and Example 1 is that the weight of the unsaturated polycyclic monomer (sodium styrene sulfonate) is adjusted to 4 parts, while the other conditions are the same as in Example 1.

[0094] Comparative Example 3

[0095] This comparative example provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this example and Example 1 is that the weight of the unsaturated carboxylic acid monomer (itaconic acid) is adjusted to 1 part, while the other conditions are the same as in Example 1.

[0096] Comparative Example 4

[0097] This comparative example provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this example and Example 1 is that the weight of the unsaturated carboxylic acid monomer (itaconic acid) is adjusted to 5 parts, while the other conditions are the same as in Example 1.

[0098] Comparative Example 5

[0099] This comparative example provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this example and Example 1 is that the weight of the unsaturated phosphate monomer (isopropenylphosphonic acid) is adjusted to 2 parts, while the other conditions are the same as in Example 1.

[0100] Comparative Example 6

[0101] This comparative example provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this example and Example 1 is that the weight of the unsaturated phosphate monomer (isopropenylphosphonic acid) is adjusted to 6 parts, while the other conditions are the same as in Example 1.

[0102] Comparative Example 7

[0103] This comparative example provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this example and Example 1 is that the unsaturated carboxylic acid monomer (itaconic acid) is not added, and the weight of the unsaturated phosphate monomer (isopropenzyme) is adjusted to 5 parts. Other conditions are the same as in Example 1.

[0104] Comparative Example 8

[0105] This comparative example provides a friction-reducing and drag-reducing agent and its preparation method. The only difference between this example and Example 1 is that the unsaturated phosphate monomer (isopropenzyme) is not added, and the weight of the unsaturated carboxylic acid monomer (itaconic acid) is adjusted to 5 parts. Other conditions are the same as in Example 1.

[0106] Performance testing

[0107] (1) Tests were conducted on cement slurries prepared by adding the friction-reducing and drag-reducing agents provided in Examples 1-7 and Comparative Examples 1-8, respectively. The cement slurry formulation was: 800g of Jiahua G-grade oil well cement (HSR), 348g of water, and 4g of the above-mentioned friction-reducing and drag-reducing agent; the cement slurry formulation of blank example 1 was: 800g of Jiahua G-grade oil well cement (HSR) and 348g of water; the specific tests are as follows:

[0108] Initial fluidity, rheological properties and thickening properties of cement slurry: Initial fluidity was obtained by testing according to GT / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures"; fluidity index (n) and consistency coefficient (k) were obtained by testing according to GB / T19139-2012 "Test Method for Cement in Oil Wells". Experimental conditions: temperature 25℃, pressure 0.1MPa.

[0109] Initial fluidity, rheological properties and thickening properties of sulfate-containing cement slurry: 2% sodium sulfate by mass was added to the above cement slurry formulation to form sulfate-containing cement slurry. The initial fluidity was then tested according to GT / T8077-2023 "Test Method for Homogeneity of Concrete Admixtures". The fluidity index (n) and consistency coefficient (k) were tested according to GB / T19139-2012 "Test Method for Cement in Oil Wells". The experimental conditions were: temperature 25℃ and pressure 0.1MPa.

[0110] The test results are shown in Table 1.

[0111] (2) The friction-reducing and drag-reducing agents provided in Examples 1-7 and Comparative Examples 1-8, respectively, were added to the 1.90 g / cm 3 Conventional density cement pastes A-1 to A-15 and 1.90 g / cm³ 3 The friction coefficient of conventional density cement slurry A was tested under the following conditions: temperature 240℃, pressure 100MPa, and heating time 100min.

[0112] The above 1.90 g / cm3 Conventional density cement slurry A-1 to A-15 comprises the following components by mass percentage: 100 parts Jiahua G-grade oil well cement (HSR), 25 parts 200-mesh quartz sand, 25 parts 600-mesh quartz sand, 2 parts microsilica, 1 part dispersant (DRS-1S, China Petroleum Engineering Technology Research Institute Co., Ltd.), 1.2 parts of the above-mentioned friction-reducing and drag-reducing agent, 5 parts fluid loss reducing agent (DRF-3L, China Petroleum Engineering Technology Research Institute Co., Ltd.), 5 parts retarder (DRH-3L, China Petroleum Engineering Technology Research Institute Co., Ltd.), 5 parts suspension stabilizer (DRK-4L, China Petroleum Engineering Technology Research Institute Co., Ltd.), and 47.8 parts water.

[0113] The above 1.90 g / cm 3 Conventional density cement slurry A, serving as blank example 2, does not contain friction-reducing agents. It comprises the following components by mass percentage: 100 parts Jiahua G-grade oil well cement (HSR), 25 parts 200-mesh quartz sand, 25 parts 600-mesh quartz sand, 2 parts silica fume, 1 part dispersant (DRS-1S, China Petroleum Engineering Technology Research Institute Co., Ltd.), 5 parts fluid loss reducer (DRF-3L, China Petroleum Engineering Technology Research Institute Co., Ltd.), 5 parts retarder (DRH-3L, China Petroleum Engineering Technology Research Institute Co., Ltd.), 5 parts suspension stabilizer (DRK-4L, China Petroleum Engineering Technology Research Institute Co., Ltd.), and 49 parts water.

[0114] The friction coefficient is calculated to be 1.90 g / cm³ according to the calculation method in SY / T 5490-2007 "Cementing Design Specification". 3 The coefficient of friction of conventional density cement slurry, taking 7-inch casing cementing as an example, is 1.90 g / cm³. 3 The flow velocity of conventional density cement grout within a 7-inch casing is set at 1.91 m / s, based on the casing inner diameter (157 mm) and the cement grout density (1.90 g / cm³). 3 The flow index and consistency coefficient are used to calculate the Reynolds number (Re) of the cement slurry, and then the friction coefficient (f) of the cement slurry is calculated. The calculation process is as follows:

[0115] The Reynolds number (Re) is calculated using the following formula:

[0116]

[0117] In the formula, ρ is the density of cement slurry; ν is the flow velocity inside the cement slurry pipe; n is the flowability index; D i denoted as the casing inner diameter; k is the consistency coefficient; the flow index (n) and consistency coefficient (k) are obtained according to GB / T19139-2012 "Test Methods for Cement in Oil Wells".

[0118] The cement grout with added friction-reducing agent flows in a turbulent state in the above-mentioned 7-inch sleeve. The friction coefficient (f) is calculated according to the following formula:

[0119]

[0120] In the formula, the values ​​of constants A and B are determined according to Table A.6 in SY / T 5480-2007.

[0121] The test results are shown in Table 2.

[0122] (3) The friction-reducing agent provided in Example 1 above was added to the test to obtain a friction-reducing agent with a viscosity of 1.90 g / cm. 3 Conventional density cement grout and 2.60 g / cm³ 3 The rheological properties, friction coefficient, settlement stability, and 48-hour strength of high-density cement slurry were tested at 240℃. The cement slurry system tested is as follows:

[0123] The above 1.90 g / cm 3 Standard density cement grout A-1;

[0124] The above 1.90 g / cm 3 Conventional density cement grout A;

[0125] 2.60g / cm 3 High-density cement slurry B-1 comprises the following components by weight: 100 parts Jiahua G-grade oil well cement (HSR), 160 parts weighting agent (micro-nano spherical weighting agent, China Petroleum Engineering Technology Research Institute Co., Ltd.), 18 parts reinforcing material (DRB-1S, China Petroleum Engineering Technology Research Institute Co., Ltd.), 2 parts stabilizer (DRK-1S, China Petroleum Engineering Technology Research Institute Co., Ltd.), 1.5 parts friction-reducing and drag-reducing agent provided in Example 1 above, 2 parts water loss reducing agent (DRF-3L, China Petroleum Engineering Technology Research Institute Co., Ltd.), 1.2 parts retarder (DRH-3L, China Petroleum Engineering Technology Research Institute Co., Ltd.), and 72 parts water;

[0126] 2.60g / cm 3 High-density cement slurry B, without added friction reducers, comprises the following components by weight: 100 parts Jiahua G-grade oil well cement (HSR), 160 parts weighting agent (micro-nano spherical weighting agent, China Petroleum Engineering Technology Research Institute Co., Ltd.), 18 parts reinforcing material (DRB-1S, China Petroleum Engineering Technology Research Institute Co., Ltd.), 2 parts stabilizer (DRK-1S, China Petroleum Engineering Technology Research Institute Co., Ltd.), 2 parts fluid loss reducer (DRF-3L, China Petroleum Engineering Technology Research Institute Co., Ltd.), 1.2 parts retarder (DRH-3L, China Petroleum Engineering Technology Research Institute Co., Ltd.), and 73.5 parts water.

[0127] Cement slurry dispensing time: Weigh the dry powder mixture and liquid mixture required for preparing cement slurry, and test the time required for the dry powder mixture to be completely mixed when it is poured into the liquid mixture in the mixer under the condition of low speed (4000 rpm) to obtain the cement slurry dispensing time.

[0128] Initial fluidity: The fluidity was tested according to GT / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures". The experimental conditions were: temperature 240℃, pressure 100MPa, and heating time 100min.

[0129] Settling stability, rheological parameters and 48h strength: These were obtained according to GB / T 19139-2012 "Test Methods for Cement in Oil Wells". The experimental conditions were: temperature 240℃, pressure 100MPa, and heating time 100min.

[0130] The test results are shown in Table 3.

[0131] Table 1. Flowability and Rheological Parameters of Cement Slurry

[0132]

[0133] In Table 1, " / " indicates that the test was not performed.

[0134] Table 21.90 g / cm 3 coefficient of friction of conventional density cement paste

[0135]

[0136]

[0137] Table 31.90 g / cm 3 and 2.60 g / cm 3 Comparison of cement grout system performance

[0138]

[0139] As can be seen from Tables 1 to 3, the friction-reducing agent provided by the present invention can be more effectively adsorbed on the surface of cement particles. Adding the friction-reducing agent provided by the present invention can improve the dispersibility of cement slurry, improve the fluidity of cement slurry, improve the rheological properties of cement slurry, and reduce the friction coefficient, thereby achieving the effect of friction reduction.

[0140] At a temperature of 25°C, the initial fluidity of the cement slurry in Example 1 was 33.0 cm, and the initial fluidity of the sulfate-containing cement slurry was 32.5 cm. The initial fluidity loss rate was only 1.5%, and the rheological properties were significantly improved compared with the blank Example 1.

[0141] Compared with Example 1, if the weight-average molecular weight of the unsaturated polyether macromonomer is too small (Example 6) or too large (Example 7), the initial fluidity of the cement slurry is slightly lower. Therefore, it can be seen that the friction-reducing agent prepared by controlling the weight-average molecular weight of the unsaturated polyether macromonomer within a specific range has better performance.

[0142] Compared with Example 1, if the weight fraction of the unsaturated polycyclic monomer is too small (Comparative Example 1) or too large (Comparative Example 2), the fluidity of the sulfate-containing cement slurry decreases and the rheological properties deteriorate. Therefore, it can be seen that the friction-reducing agent prepared by controlling the weight fraction of the unsaturated polycyclic monomer within a specific range has better performance.

[0143] Compared with Example 1, if the weight fraction of the unsaturated carboxylic acid monomer is too small (Comparative Example 3), the initial fluidity of the cement slurry is low; if the weight fraction of the unsaturated carboxylic acid monomer is too large (Comparative Example 4), the initial fluidity of the cement slurry is also low, and under sulfate-containing conditions, the initial fluidity loss rate of the cement slurry is relatively large, at 10.2%. Therefore, it can be concluded that the friction-reducing agent prepared by controlling the weight fraction of the unsaturated carboxylic acid monomer within a specific range has better performance.

[0144] Compared with Example 1, if the weight fraction of unsaturated phosphate monomer is too small (Comparative Example 5), the initial fluidity is low, and the initial fluidity loss rate of cement slurry is large at 11.1% under sulfate-containing conditions; if the weight fraction of unsaturated phosphate monomer is too large (Comparative Example 6), the initial fluidity is low, and the initial fluidity loss rate is large at 6.7% under sulfate-containing conditions. Therefore, it can be seen that the friction-reducing and drag-reducing agent prepared by controlling the weight fraction of unsaturated phosphate monomer within a specific range has better performance.

[0145] Compared with Example 1, if no unsaturated carboxylic acid monomer is added (Comparative Example 7), the initial fluidity is lower, and the initial fluidity loss rate is larger at 9.7% under sulfate conditions; if no unsaturated phosphate monomer is added (Comparative Example 8), the initial fluidity is also lower. Therefore, it can be seen that the friction-reducing agent prepared by using unsaturated phosphate monomer to replace part of the unsaturated carboxylic acid monomer and the combination of unsaturated carboxylic acid monomer and unsaturated phosphate monomer has better performance.

[0146] As shown in Table 1, after adding sodium sulfate to the cement slurry, the initial fluidity and rheological properties of the sulfate-containing cement slurries containing the friction-reducing and drag-reducing agents provided in Examples 1-7 did not change significantly, and the initial fluidity was relatively high. However, the initial fluidity loss rate of the cement slurries containing the friction-reducing and drag-reducing agents provided in Comparative Examples 1-8 was higher, or the rheological properties deteriorated significantly. Therefore, it can be concluded that the rheological properties and fluidity of the cement slurries containing the friction-reducing and drag-reducing agents provided in Examples 1-7 are less affected by the sulfate content, exhibiting lower sulfate sensitivity and stronger adaptability.

[0147] As shown in Table 2, compared with blank example 2, the friction reduction agent provided by the present invention can reduce the friction coefficient by more than 20%, which has a good effect on reducing the friction of cement slurry.

[0148] As shown in Table 3, the addition of the friction-reducing agent provided in Example 1 at a concentration of 1.90 g / cm³... 3 Conventional density cement paste (A-1) and 2.60 g / cm³ 3 The settling time of high-density cement slurry (B-1) was reduced in all cases, and the settling time did not exceed 30 seconds. Compared with cement slurry without the friction-reducing agent provided in Example 1, the friction coefficient was significantly reduced after adding the friction-reducing agent provided in Example 1, reaching 1.90 g / cm³. 3 The friction coefficient of the cement paste system decreased by 46.5%, to 2.60 g / cm³. 3 The friction coefficient of the cement slurry system decreased by 26.7%, meeting the requirements for on-site mixing and pumping; and after curing at 240℃, it reached 1.90 g / cm³. 3 Conventional density cement grout and 2.60 g / cm³ 3 High-density cement slurry exhibits good settling stability and is free of free liquid. Therefore, the friction-reducing agent provided by this invention can effectively improve the rheological properties of cement slurry, reduce the friction coefficient of cement slurry, and improve the pumping efficiency of cement slurry. It also has no adverse effects on properties such as settling stability, free liquid, and strength, and can meet the application requirements under ultra-high temperature conditions of 240℃.

[0149] The applicant declares that the present invention is illustrated by the above embodiments to demonstrate a friction-reducing and drag-reducing agent, its preparation method, and its application. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A friction-reducing and drag-reducing agent, characterized in that, The raw materials for preparing the friction-reducing and drag-reducing agent include the following components by weight: 20-40 parts of unsaturated polyether macromonomer, 0.1-0.5 parts of initiator, 0.02-0.2 parts of chain transfer agent, 2-4 parts of unsaturated carboxylic acid monomer, 2-3 parts of unsaturated polycyclic monomer, 3-5 parts of unsaturated phosphate monomer, and 120-175 parts of water.

2. The friction-reducing and drag-reducing agent according to claim 1, characterized in that, The unsaturated polyether macromonomer includes methyl allyl polyoxyethylene ether; Preferably, the weight-average molecular weight of the methyl allyl polyoxyethylene ether is 2000-4000.

3. The friction-reducing and drag-reducing agent according to claim 1 or 2, characterized in that, The initiator includes any one or a combination of at least two of potassium persulfate, ammonium persulfate, or sodium persulfate.

4. The friction-reducing and drag-reducing agent according to any one of claims 1-3, characterized in that, The chain transfer agent includes any one or a combination of at least two of 3-mercaptopropionic acid, mercaptoethanol, or isopropanol.

5. The friction-reducing and drag-reducing agent according to any one of claims 1-4, characterized in that, The unsaturated carboxylic acid monomer includes any one or a combination of at least two of acrylic acid, itaconic acid, maleic acid, or fumaric acid.

6. The friction-reducing and drag-reducing agent according to any one of claims 1-5, characterized in that, The unsaturated polycyclic monomers include sodium p-styrenesulfonate and / or vinylphenylsulfonic acid; Preferably, the unsaturated phosphate monomer is isopropenzyme and / or diethyl vinylphosphonate.

7. The friction-reducing and drag-reducing agent according to any one of claims 1-6, characterized in that, The raw materials for preparing the friction-reducing and drag-reducing agent also include a pH adjuster; Preferably, the pH adjuster comprises any one or a combination of at least two of sodium hydroxide, sodium carbonate, or potassium hydroxide.

8. A method for preparing a friction-reducing and drag-reducing agent as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: mixing unsaturated polyether macromonomer, initiator, chain transfer agent, unsaturated carboxylic acid monomer, unsaturated polycyclic monomer, unsaturated phosphate monomer and water, reacting to obtain the friction-reducing and drag-reducing agent.

9. The preparation method according to claim 8, characterized in that, The mixing also includes mixing with a pH adjuster; Preferably, the preparation method specifically includes the following steps: (1) Mix the unsaturated polyether macromonomer with a portion of water to obtain a base solution; (2) Mix the initiator, chain transfer agent and a portion of water to obtain component A; (3) Mix unsaturated carboxylic acid monomer, unsaturated polycyclic monomer, unsaturated phosphate monomer and some water to obtain component B; (4) Heat the base solution obtained in step (1), add component A obtained in step (2) and component B obtained in step (3), keep the reaction at the temperature, add pH adjuster and the remaining water to obtain the friction reducing agent. Steps (1), (2), and (3) can be performed in any order, or simultaneously. Preferably, the water in step (1) is 50-70 parts by weight; Preferably, the water in step (2) is in the form of 10-20 parts by weight; Preferably, the water in step (3) is 10-20 parts by weight; Preferably, the heating in step (4) is to heat to 60-80°C; Preferably, the addition of component A obtained in step (2) and component B obtained in step (3) in step (4) specifically refers to the simultaneous addition of component A obtained in step (2) and component B obtained in step (3). Preferably, the time for adding component A in step (2) and component B in step (3) is 1-3 hours each. Preferably, the temperature of the heat preservation reaction in step (4) is 60-80℃ and the time is 1-3h; Preferably, the addition of pH adjuster in step (4) is to add pH adjuster to a pH of 6-7.

10. A cement grout, characterized in that, The cement slurry includes the friction-reducing agent as described in any one of claims 1-7.

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