A high temperature resistant broad spectrum environmentally friendly retarder for cementing and its preparation method and application

Abstract

The present invention relates to the technical field of cementing materials, and in particular to a high temperature resistant broad spectrum environmentally friendly retarder for cementing and its preparation method and application, comprising chemically modified lignin sulfonate and a polymer copolymer, wherein the mass ratio of the chemically modified lignin sulfonate and the polymer copolymer is 2-5:5-8; the chemically modified lignin sulfonate is prepared by modifying the lignin sulfonate using an oxidant and a sulfonating agent; the polymer copolymer is prepared by free radical aqueous solution polymerization after adjusting the pH of unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side group vinyl monomers. The high temperature resistant retarder prepared by the present invention can effectively adjust the thickening time of cement slurry, and can ensure that the cement slurry maintains good flowability and pumpability before being pumped to the required position at a high temperature of 130-220°C, thereby overcoming the abnormal phenomena such as the sensitive addition amount of ordinary retarders, easy degradation at high temperature, and the existence of "core wrapping" and "bulging".

Description

Technical Field

[0001] The invention relates to the technical field of cementing materials, and in particular to a high-temperature resistant broad-spectrum environmentally friendly retarder for cementing, a preparation method thereof, and application thereof in oil well cement. Background Art

[0002] In recent years, as oil and gas exploration and development have rapidly advanced to depths beyond 8,000 m, the length of cement slurry sealing sections has also increased, and therefore, higher requirements have been placed on the thickening and setting time of cement slurry. Oil well cement retarder is a chemical additive used in oil well cementing operations, mainly used to extend the thickening and setting time of cement slurry. This additive can improve the flexibility of construction and ensure that the cement slurry does not start to solidify until it reaches the predetermined depth and is pumped.

[0003] At present, oil well cement retarders mainly include lignin sulfonate, cellulose and its derivatives, sugar compounds, organic phosphonates, polymers, etc. Lignin sulfonate is used because of its low cost and wide raw material resources, but the application temperature is generally not more than 150℃ when used alone; cellulose and its derivatives usually make cement slurry thicker, thus affecting the rheological properties of slurry; organic phosphonates have excellent retarding properties, but their dosage sensitivity is too strong, and the dosage must be strictly controlled when used. In recent years, polymer retarders have been widely studied because of their controllable molecular structure and stable performance; but the advantages of this type of retarder are insensitivity to dosage, wide application temperature range, good compatibility with other admixtures, etc.; but it is easy to degrade and fail under high temperature conditions, especially when cementing spans a large temperature difference of 140~180℃, cement slurry may have abnormal phenomena such as "heart wrapping" and "bulging" that endanger construction safety. Therefore, it is urgent to provide a new type of high temperature resistant broad-spectrum retarder to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a high-temperature resistant broad-spectrum environmentally friendly retarder for cementing, and a preparation method and application thereof. The prepared high-temperature resistant broad-spectrum environmentally friendly retarder can work stably in a high-temperature environment of 130-220°C, significantly improving the construction performance of oil well cement slurry. Compared with traditional retarders, it exhibits excellent stability and is not easy to degrade, effectively avoiding the problem of dosage sensitivity caused by temperature fluctuations, as well as cementing abnormalities such as "core wrapping" and "bulging" that may occur when the temperature span is large.

[0005] To achieve the above object, the present invention provides a high temperature resistant broad spectrum environmentally friendly retarder for cementing, comprising chemically modified lignin sulfonate and a polymer copolymer, wherein the mass ratio of the chemically modified lignin sulfonate to the polymer copolymer is 2-5:5-8;

[0006] The chemically modified lignin sulfonate is prepared by modifying the lignin sulfonate using an oxidizing agent and a sulfonating agent;

[0007] The high molecular copolymer is prepared by free radical aqueous solution polymerization reaction of unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side-group vinyl monomers after adjusting pH.

[0008] The chemically modified lignin sulfonate used in the present invention is obtained by oxidation modification and sulfonation modification of lignin sulfonate with excellent slow setting performance, so that the lignin sulfonate undergoes a series of fragmentation reactions such as increase of phenolic hydroxyl group, increase of carboxyl group, increase of sulfonic acid group and increase of molecular weight under the synergistic action of oxidant and sulfonating agent. The increase of carboxyl group and sulfonic acid group enhances the adsorption and chelation ability of lignin sulfonate, so that it can chelate more metal ions and cement hydration products, and can effectively alleviate the possible "heart-wrapping" and "bulging" phenomena. The increase of molecular weight improves its temperature resistance.

[0009] The present invention selects sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side-group vinyl monomers as raw materials to synthesize high molecular copolymers. The sulfonic acid group of the sulfonic acid monomer can provide excellent adsorption capacity and certain heat and salt resistance. The unsaturated carboxylic acid monomer can provide strong adsorption and chelation capabilities for the polymer. The macrocyclic side-group vinyl monomer, the steric hindrance of its cyclic side group, can improve the rigidity of the molecular chain, alleviate the curling phenomenon of the polymer molecular chain during the adsorption and chelation process, and help the uniform distribution of the molecular chain in the cement slurry.

[0010] Lignin sulfonate is a naturally occurring polymer compound, mainly derived from lignin. It is biodegradable and renewable because it exists naturally in the cell walls of plants. After modification, its molecules contain a large number of functional groups such as phenolic hydroxyl groups and alcoholic hydroxyl groups. These groups can form physical or chemical crosslinks with polymer copolymers. The formation of this crosslinked network can improve the temperature resistance of the material. At the same time, the functional groups of chemically modified lignin sulfonate increase. These functional groups not only enhance the water solubility and dispersibility of lignin sulfonate itself, but also form hydrogen bonds and other interactions with polymer copolymers, further improving the stability of the material. The improvement of the dispersing effect of lignin sulfonate is beneficial to the dispersibility of polymer copolymers in aqueous systems and the adsorption and chelation of polymer copolymer segments on cement particles, thereby improving its retarding effect. The fully dispersed cement slurry system also has a certain inhibitory effect on the core and bulging phenomenon. In addition, as a natural polymer, lignin sulfonate is also an advantage in its application in oil well cement cementing due to its renewability and biodegradability. This helps to reduce the impact of oil well operations on the environment and meets the current requirements of sustainable development.

[0011] Preferably, the lignin sulfonate includes one of sodium lignin sulfonate and calcium lignin sulfonate;

[0012] The oxidizing agent includes one or two of hydrogen peroxide, potassium permanganate, and potassium dichromate;

[0013] The sulfonating agent includes one or more of sulfamic acid, sodium sulfite, carbon disulfide, and methyl bromoacetate.

[0014] Preferably, the molar ratio of the unsaturated sulfonic acid monomer, the unsaturated carboxylic acid monomer and the macrocyclic side vinyl monomer is 4-7:2-4:1-2.

[0015] Preferably, the unsaturated sulfonic acid monomers include one or two of styrene sulfonic acid, sodium propylene sulfonate, 2-acrylamide-2-methylpropane sulfonic acid, 2-hydroxy-3-allyl sulfonic acid, and sodium methyl propylene sulfonate;

[0016] The unsaturated carboxylic acid monomers include one or two of itaconic acid, maleic acid, acrylic acid, and fumaric acid;

[0017] The macrocyclic side-group vinyl monomers include one or more of N-vinyl pyrrolidone, N-vinyl caprolactam, 1,5-cyclooctadiene-3-ethylene, 4-vinylcyclohexene, and cyclododecahexaene-1-ethylene.

[0018] Preferably, the initiator of the free radical aqueous solution polymerization reaction is a redox initiator, and the redox initiator includes two of ammonium persulfate, ammonium sulfite, sodium bisulfite, and potassium persulfate, and is compounded in a mass ratio of 1:1.

[0019] A method for preparing a high temperature resistant broad-spectrum environmentally friendly retarder for cementing, comprising the following steps:

[0020] S1, modifying lignin sulfonate using an oxidant and a sulfonating agent to obtain chemically modified lignin sulfonate;

[0021] S2, adjusting the pH of unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side-group vinyl monomers, and preparing a high molecular copolymer by free radical aqueous solution polymerization;

[0022] S3. The chemically modified lignin sulfonate in S1 and the high molecular copolymer in S2 are mixed in a mass ratio of 2-5:5-8 to obtain a high temperature resistant retarder.

[0023] Preferably, step S1 comprises:

[0024] S1.1. Add lignin sulfonate into a three-necked flask, add deionized water and stir to dissolve to obtain a lignin sulfonate solution, the mass concentration of the lignin sulfonate solution is 25%~35%;

[0025] S1.2, add 3% to 8% of the total mass of lignin sulfonate oxidant to the three-necked flask in S1.1, raise the temperature to 80°C, and react for 3 hours;

[0026] S1.3, add 30% to 50% of the total mass of lignin sulfonate sulfonating agent and 5% to 20% of formaldehyde to the three-necked flask in S1.2, adjust the pH of the solution to 8 to 9 with a pH adjuster, heat to 90°C, react for 5 hours, and cool to obtain a chemically modified lignin sulfonate aqueous solution;

[0027] S1.4, removing water from the chemically modified lignin sulfonate aqueous solution, drying it, and grinding it into powder to obtain chemically modified lignin sulfonate.

[0028] Preferably, the pH regulator in S1.3 is sodium hydroxide.

[0029] Preferably, step S2 comprises,

[0030] S2.1. Dissolve unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side-group vinyl monomers in deionized water at a molar ratio of 4-7:2-4:1-2 to obtain a mixed solution, wherein the total mass concentration of the unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side-group vinyl monomers in the mixed solution is 20%-25%;

[0031] S2.2, adjusting the pH value of the mixed solution in S2.1 to 2-3 to obtain an acidic mixed solution, and then heating it to 60-70°C;

[0032] S2.3, add a redox initiator dropwise to the acidic mixed solution of S2.2, wherein the amount of the redox initiator is 0.5% to 1% of the total mass of the unsaturated sulfonic acid monomer, the unsaturated carboxylic acid monomer and the macrocyclic side vinyl monomer, the dripping speed is 1 drop per 3 to 4 seconds, and the reaction is carried out at a constant temperature for 4 hours;

[0033] S2.4. Remove water from the solution after the reaction in S2.3, dry it, grind it into powder, and obtain a high molecular copolymer.

[0034] The invention discloses an application of a high temperature resistant broad-spectrum environmentally friendly retarder for cementing, which is applied to oil well cement.

[0035] Beneficial effects of the present invention:

[0036] (1) The high-temperature resistant broad-spectrum environmentally friendly retarder for cementing provided by the present invention can work stably in a high-temperature environment of 130~220℃ due to its unique chemical structure, and significantly improve the construction performance of oil well cement slurry. Compared with traditional retarders, the high-temperature resistant broad-spectrum environmentally friendly retarder for cementing of the present invention shows excellent stability at high temperatures and is not easy to degrade, effectively avoiding the problem of dosage sensitivity caused by temperature fluctuations, as well as cementing abnormalities such as "core wrapping" and "bulging" that may occur when the temperature span is large.

[0037] (2) The high temperature resistant broad spectrum environmentally friendly retarder for cementing of the present invention can meet the retarding requirements of 130-220°C, the thickening curve has no abnormal gelling problems such as "core" and "bulging", and the amount of retarder added has a good linear relationship.

[0038] (3) The high-temperature resistant broad-spectrum environmentally friendly retarder for cementing of the present invention has good compatibility with a variety of admixtures, does not affect the working performance of other admixtures, can accurately control the thickening time of cement slurry, and ensure that the cement slurry always maintains good fluidity and pumpability during the process of being pumped to the predetermined position, thereby ensuring the safety of cementing construction and the quality of cementing.

[0039] (4) The method for preparing a high temperature resistant broad-spectrum environmentally friendly retarder for cementing of the present invention has a reliable principle, simple operation, readily available raw materials, low toxicity to the environment, and is beneficial to environmental protection.

[0040] (5) The high temperature resistant broad spectrum environmentally friendly retarder for cementing of the present invention effectively avoids abnormal gelation of cement hydration products at high temperature by introducing chemically modified lignin sulfonate and utilizing its adsorption and chelation effect on metal ions and cement hydration products in cement slurry.

[0041] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is the thickening curve of the oil well cement slurry prepared using the high temperature resistant retarder of Example 1 of the present invention;

[0043] Figure 2 is the thickening curve of the oil well cement slurry prepared by using the retarder of Comparative Example 1 of the present invention;

[0044] Figure 3 This is the thickening curve of the oil well cement slurry prepared using the retarder of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with the accompanying drawings and embodiments. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs. The above-mentioned features or features mentioned in the specific examples mentioned in the present invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0046] Example 1

[0047] The invention provides a high temperature resistant broad-spectrum environmentally friendly retarder for cementing, which is prepared by mixing chemically modified sodium lignin sulfonate and a high molecular copolymer in a mass ratio of 2:8.

[0048] The preparation method of the above-mentioned high temperature resistant retarder comprises the following steps:

[0049] S1, modifying sodium lignin sulfonate using an oxidant and a sulfonating agent to obtain chemically modified sodium lignin sulfonate;

[0050] S1.1. Add sodium lignin sulfonate into a three-necked flask, add deionized water and stir to dissolve to obtain a sodium lignin sulfonate solution, so that the sodium lignin sulfonate is fully dissolved, and the mass concentration of the sodium lignin sulfonate solution is 25%;

[0051] S1.2, add 4% hydrogen peroxide of the total mass of sodium lignin sulfonate to the three-necked flask in S1.1, raise the temperature to 80°C, and react for 3 hours;

[0052] S1.3, add 35% of the total mass of sodium lignin sulfonate aminosulfonic acid and 10% of formaldehyde to the three-necked flask in S1.2, adjust the pH of the solution to 8 with sodium hydroxide, raise the temperature to 90°C, react for 5 hours, and cool after the reaction to obtain a chemically modified sodium lignin sulfonate aqueous solution;

[0053] S1.4. The chemically modified sodium lignin sulfonate aqueous solution is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then the solid matter is ground into powder after drying to obtain chemically modified sodium lignin sulfonate.

[0054] S2, p-styrene sulfonic acid, itaconic acid and N-vinyl caprolactam, after adjusting the pH, adopt free radical aqueous solution polymerization method to prepare a high molecular copolymer;

[0055] S2.1, dissolving styrene sulfonic acid, itaconic acid and N-vinyl caprolactam in deionized water at a molar ratio of 5:2:1 to obtain a mixed solution, wherein the total mass concentration of the three monomers in the mixed solution is 20%;

[0056] S2.2, adjusting the pH value of the mixed solution in S2.1 to 2 to obtain an acidic mixed solution, and then heating the solution to 65°C and maintaining the temperature;

[0057] S2.3, add a redox initiator dropwise to the acidic mixed solution of S2.2, the amount of the redox initiator is 1% of the total mass of the above three monomers, the redox initiator is ammonium sulfate and ammonium sulfite mixed in a ratio of 1:1 and dissolved in deionized water, the dripping speed is 1 drop per 3-4 seconds, and the reaction is maintained at a constant temperature for 4 hours;

[0058] S2.4. The solution after the reaction in S2.3 is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then after drying, the solid matter is ground into powder to obtain a high molecular copolymer.

[0059] S3, mixing the chemically modified sodium lignin sulfonate of S1 and the high molecular copolymer of S2 in a mass ratio of 2:8 to obtain a high temperature resistant retarder.

[0060] Example 2

[0061] The invention provides a high temperature resistant broad-spectrum environmentally friendly retarder for cementing, which is prepared by mixing chemically modified calcium lignin sulfonate and a high molecular copolymer in a mass ratio of 3:7.

[0062] The preparation method of the above-mentioned high temperature resistant retarder comprises the following steps:

[0063] S1, modifying calcium lignin sulfonate using an oxidant and a sulfonating agent to obtain chemically modified calcium lignin sulfonate;

[0064] S1.1. Add calcium lignin sulfonate into a three-necked flask, add deionized water and stir to dissolve to obtain a calcium lignin sulfonate solution, so that the calcium lignin sulfonate is fully dissolved, and the mass concentration of the calcium lignin sulfonate solution is 25%;

[0065] S1.2. Add 4% of the total mass of calcium lignin sulfonate into the three-necked flask in S1.1, increase the temperature to 80°C, and react for 3 hours;

[0066] S1.3, add 35% of the total mass of calcium lignin sulfonate aminosulfonic acid and 10% of formaldehyde to the three-necked flask of S1.2, adjust the pH of the solution to 8 with sodium hydroxide, raise the temperature to 90°C, react for 5 hours, and cool after the reaction to obtain a chemically modified calcium lignin sulfonate aqueous solution;

[0067] S1.4. The chemically modified calcium lignin sulfonate aqueous solution is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then the solid matter is ground into powder after drying to obtain chemically modified calcium lignin sulfonate.

[0068] S2, p-styrene sulfonic acid, itaconic acid and N-vinyl caprolactam, after adjusting the pH, adopt free radical aqueous solution polymerization method to prepare a high molecular copolymer;

[0069] S2.1, dissolving styrene sulfonic acid, itaconic acid and N-vinyl caprolactam in deionized water at a molar ratio of 5:2:1 to obtain a mixed solution, wherein the total mass concentration of the three monomers in the mixed solution is 20%;

[0070] S2.2, adjusting the pH value of the mixed solution in S2.1 to 2 to obtain an acidic mixed solution, and then heating the solution to 65°C and maintaining the temperature;

[0071] S2.3, add a redox initiator dropwise to the acidic mixed solution of S2.2, the amount of the redox initiator is 1% of the total mass of the above three monomers, the redox initiator is ammonium sulfate and ammonium sulfite mixed in a ratio of 1:1 and dissolved in deionized water, the dripping speed is 1 drop per 3-4 seconds, and the reaction is maintained at a constant temperature for 4 hours;

[0072] S2.4. The solution after the reaction in S2.3 is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then after drying, the solid matter is ground into powder to obtain a high molecular copolymer.

[0073] S3, mixing the chemically modified calcium lignin sulfonate in S1 and the high molecular copolymer in S2 in a mass ratio of 3:7 to obtain a high temperature resistant retarder.

[0074] Example 3

[0075] The invention provides a high temperature resistant broad-spectrum environmentally friendly retarder for cementing, which is prepared by mixing chemically modified sodium lignin sulfonate and a high molecular copolymer in a mass ratio of 3:7.

[0076] The preparation method of the above-mentioned high temperature resistant retarder comprises the following steps:

[0077] S1, modifying sodium lignin sulfonate using an oxidant and a sulfonating agent to obtain chemically modified sodium lignin sulfonate;

[0078] S1.1. Add sodium lignin sulfonate into a three-necked flask, add deionized water and stir to dissolve to obtain a sodium lignin sulfonate solution, so that the sodium lignin sulfonate is fully dissolved, and the mass concentration of the sodium lignin sulfonate solution is 30%;

[0079] S1.2, add potassium permanganate (3% of the total mass of sodium lignin sulfonate) to the three-necked flask in S1.1, raise the temperature to 80°C, and react for 3 hours;

[0080] S1.3, add 30% of the total mass of sodium lignin sulfonate sodium sulfite and 10% of formaldehyde to the three-necked flask in S1.2, adjust the solution pH to 8 with sodium hydroxide, raise the temperature to 90°C, react for 5 hours, and cool after the reaction to obtain a chemically modified sodium lignin sulfonate aqueous solution;

[0081] S1.4. The chemically modified sodium lignin sulfonate aqueous solution is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then the solid matter is ground into powder after drying to obtain chemically modified sodium lignin sulfonate.

[0082] S2, sodium methyl methacrylate sulfonate, maleic acid and N-vinyl caprolactam were used to adjust the pH and then a high molecular weight copolymer was prepared by free radical aqueous solution polymerization;

[0083] S2.1, dissolving sodium methyl methacrylate sulfonate, maleic acid and N-vinyl caprolactam in a molar ratio of 6:3:2 in deionized water to obtain a mixed solution, wherein the total mass concentration of the above three monomers in the mixed solution is 20%;

[0084] S2.2, adjusting the pH value of the mixed solution in S2.1 to 2 to obtain an acidic mixed solution, and then heating the solution to 65°C and maintaining the temperature;

[0085] S2.3, add a redox initiator dropwise to the acidic mixed solution of S2.2, the amount of the redox initiator is 0.8% of the total mass of the above three monomers, the redox initiator is ammonium sulfate and ammonium sulfite mixed in a ratio of 1:1 and dissolved in deionized water, the dripping speed is 1 drop per 3-4 seconds, and the reaction is maintained at a constant temperature for 4 hours;

[0086] S2.4. The solution after the reaction in S2.3 is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then after drying, the solid matter is ground into powder to obtain a high molecular copolymer.

[0087] S3, mixing the chemically modified sodium lignin sulfonate of S1 and the high molecular copolymer of S2 in a mass ratio of 3:7 to obtain a high temperature resistant retarder.

[0088] Example 4

[0089] The invention provides a high temperature resistant broad-spectrum environmentally friendly retarder for cementing, which is prepared by mixing chemically modified sodium lignin sulfonate and a high molecular copolymer in a mass ratio of 4:6.

[0090] The preparation method of the above-mentioned high temperature resistant retarder comprises the following steps:

[0091] S1, modifying sodium lignin sulfonate using an oxidant and a sulfonating agent to obtain chemically modified sodium lignin sulfonate;

[0092] S1.1. Add sodium lignin sulfonate into a three-necked flask, add deionized water and stir to dissolve to obtain a sodium lignin sulfonate solution, so that the sodium lignin sulfonate is fully dissolved, and the mass concentration of the sodium lignin sulfonate solution is 35%;

[0093] S1.2, add potassium permanganate (5% of the total mass of sodium lignin sulfonate) to the three-necked flask in S1.1, raise the temperature to 80°C, and react for 3 hours;

[0094] S1.3, add 30% of the total mass of sodium lignin sulfonate sodium sulfite and 10% of formaldehyde to the three-necked flask of S1.2, adjust the solution pH to 8 with sodium hydroxide, raise the temperature to 90°C, react for 5 hours, and cool after the reaction to obtain a chemically modified sodium lignin sulfonate aqueous solution;

[0095] S1.4. The chemically modified sodium lignin sulfonate aqueous solution is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then the solid matter is ground into powder after drying to obtain chemically modified sodium lignin sulfonate.

[0096] S2, sodium methyl methacrylate sulfonate, maleic acid and N-vinyl caprolactam were used to adjust the pH and then a high molecular weight copolymer was prepared by free radical aqueous solution polymerization;

[0097] S2.1, dissolving sodium methyl methacrylate sulfonate, maleic acid and N-vinyl caprolactam in a molar ratio of 6:4:1 in deionized water to obtain a mixed solution, wherein the total mass concentration of the above three monomers in the mixed solution is 20%;

[0098] S2.2, adjusting the pH value of the mixed solution in S2.1 to 3 to obtain an acidic mixed solution, and then heating the solution to 70°C and maintaining the temperature;

[0099] S2.3, add a redox initiator dropwise to the acidic mixed solution of S2.2, the amount of the redox initiator is 1% of the total mass of the above three monomers, the redox initiator is ammonium sulfate and ammonium sulfite mixed in a ratio of 1:1 and dissolved in deionized water, the dripping speed is 1 drop per 3-4 seconds, and the reaction is maintained at a constant temperature for 4 hours;

[0100] S2.4. The solution after the reaction in S2.3 is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then after drying, the solid matter is ground into powder to obtain a high molecular copolymer.

[0101] S3, mixing the chemically modified sodium lignin sulfonate of S1 and the high molecular copolymer of S2 in a mass ratio of 4:6 to obtain a high temperature resistant retarder.

[0102] Comparative Example 1

[0103] A retarder is prepared by mixing sodium lignin sulfonate and a high molecular copolymer in a mass ratio of 2:8.

[0104] The preparation method of the retarder comprises the following steps:

[0105] S1. Weigh sodium lignin sulfonate.

[0106] S2, p-styrene sulfonic acid, itaconic acid and N-vinyl caprolactam, after adjusting the pH, adopt free radical aqueous solution polymerization method to prepare a high molecular copolymer;

[0107] S2.1, dissolving styrene sulfonic acid, itaconic acid and N-vinyl caprolactam in deionized water at a molar ratio of 5:2:1 to obtain a mixed solution, wherein the total mass concentration of the three monomers in the mixed solution is 20%;

[0108] S2.2, adjusting the pH value of the mixed solution in S2.1 to 2 to obtain an acidic mixed solution, and then heating the solution to 65°C and maintaining the temperature;

[0109] S2.3, add a redox initiator dropwise to the acidic mixed solution of S2.2, the amount of the redox initiator is 1% of the total mass of the above three monomers, the redox initiator is ammonium sulfate and ammonium sulfite mixed in a ratio of 1:1 and dissolved in deionized water, the dripping speed is 1 drop per 3-4 seconds, and the reaction is maintained at a constant temperature for 4 hours;

[0110] S2.4. The solution after the reaction in S2.3 is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then after drying, the solid matter is ground into powder to obtain a high molecular copolymer.

[0111] S3. The sodium lignin sulfonate of S1 and the high molecular weight copolymer of S2 are mixed in a mass ratio of 2:8 to obtain a retarder.

[0112] Comparative Example 2

[0113] A retarder consisting solely of high molecular weight copolymers.

[0114] The preparation method of the retarder comprises the following steps:

[0115] S1, p-styrene sulfonic acid, itaconic acid and N-vinyl caprolactam are used to adjust the pH to prepare a high molecular copolymer by free radical aqueous solution polymerization;

[0116] S1.1, dissolving styrene sulfonic acid, itaconic acid and N-vinyl caprolactam in deionized water at a molar ratio of 5:2:1 to obtain a mixed solution, wherein the total mass concentration of the three monomers in the mixed solution is 20%;

[0117] S1.2, adjusting the pH value of the mixed solution in S1.1 to 2 to obtain an acidic mixed solution, then heating it to 65°C and maintaining this temperature;

[0118] S1.3, add a redox initiator dropwise to the acidic mixed solution of S1.2, the amount of the redox initiator is 1% of the total mass of the above three monomers, the redox initiator is ammonium sulfate and ammonium sulfite mixed in a ratio of 1:1 and dissolved in deionized water, the dripping speed is 1 drop per 3-4 seconds, and the reaction is maintained at a constant temperature for 4 hours;

[0119] S1.4. The solution after the reaction in S1.3 is extracted by acetone or anhydrous ethanol, or the solution is directly ventilated and dried at a certain temperature to remove water, and then after drying, the solid matter is ground into powder to obtain a high molecular copolymer as a retarder.

[0120] Performance Test:

[0121] The high temperature retarders of Examples 1-4 and the retarders prepared in Comparative Examples 1-2 were applied to oil well cement. The basic formula of oil well cement slurry was: Jiahua G-grade oil well cement + 50% quartz sand (200 mesh) + 1% dispersant (USZ) + 5% fluid loss agent (DRF-3L) + 3.5% retarder + 1.5% suspension stabilizer (SD89) + water, wherein SD89 was provided by Sichuan Chuanqing Downhole Technology Co., Ltd., and DRF-3L was provided by the Drilling Engineering Technology Research Institute of China National Petroleum Corporation. The mass percentages of each component were calculated based on the weight of Jiahua G-grade oil well cement, and the water-cement ratio was 0.44. The prepared oil well cement slurry was tested for properties such as thickening time and fluidity at 180°C, and the results are shown in Table 1.

[0122] Table 1 Basic properties of oil well cement slurries prepared with different retarders at 220℃

[0123] ;

[0124] It can be seen from Table 1 that the thickening time of Examples 1 to 4 at 3.5% addition meets the thickening time requirements of GB_T19139-2012, and there is no core-encapsulation or bulging phenomenon; in contrast, the thickening time of Comparative Example 1 is only 212 minutes, and there is bulging phenomenon; the thickening time of Comparative Example 2 is only 221 minutes, and there is core-encapsulation phenomenon.

[0125] The high temperature resistant retarder of Examples 1-4 and the retarder prepared in Comparative Examples 1-2 were applied to oil well cement. The basic formula of the oil well cement slurry was: Jiahua G-grade oil well cement + 50% quartz sand (200 mesh) + 1% dispersant (USZ) + Y% fluid loss reducer (DRF-3L) + 3.5% retarder + 1.5% suspension stabilizer (SD89) + water. The water loss of the above-prepared oil well cement slurry was measured at 180°C. The results are shown in Table 2.

[0126] Table 2 Water loss properties of oil well cement slurries prepared with different retarders at 220℃

[0127] ;

[0128] As can be seen from Table 2, the high temperature retarders prepared in Examples 1-4 have a good compatibility with the dehydrating agent, and the water loss of the oil well cement slurries prepared therefrom is below 50 mL. However, the water loss of the oil well cement slurries prepared using the retarders in Comparative Examples 1 and 2 is always above 50 mL, and the compatibility with the dehydrating agent is not good.

[0129] The high temperature resistant retarder prepared in Example 1 was used to prepare oil well cement slurry, and the basic formula of cement slurry was: Jiahua G-grade oil well cement + 50% quartz sand (200 mesh) + 1% dispersant (USZ) + 4% fluid loss agent (DRF-3L) + X% retarder + 1.5% suspension stabilizer (SD89) + water, wherein the mass percentage of each component was calculated based on the weight of Jiahua G-grade oil well cement, and the water-cement ratio was 0.44. The thickening time of the prepared oil well cement slurry was measured at 130-220°C, and the results are shown in Table 3.

[0130] Table 3 Thickening time of oil well cement slurry prepared using the high temperature retarder of Example 1 at 130-220°C

[0131] ;

[0132] It can be clearly seen from the data in Table 3 that the high temperature resistant broad spectrum environmentally friendly retarder prepared in Example 1 of the present invention has a good linear relationship of dosage, which is convenient for construction personnel to accurately control the thickening performance of cement slurry according to actual needs. In the wide temperature range of 130~220℃, the retarder of the present invention can effectively delay the thickening time of cement slurry without super retarding phenomenon, thereby ensuring that the cement slurry maintains ideal pumpability during the entire cementing process. It is suitable for cementing operations with long sealing sections, large temperature differences, deep wells, and ultra-deep wells.

[0133] Figure 1 is the thickening curve of the oil well cement slurry prepared using the high temperature resistant retarder of Example 1 of the present invention; Figure 2 is the thickening curve of the oil well cement slurry prepared by using the retarder of Comparative Example 1 of the present invention; Figure 3is the thickening curve of the oil well cement slurry prepared by using the retarder of Comparative Example 2 of the present invention; Figures 1 to 3 It can be seen that the consistency line of the cement slurry added with Example 1 is basically stable, without bulging phenomenon, the temperature line does not fluctuate greatly during the heating and insulation stages, there is no core phenomenon, and the thickening time is more than 400 minutes. The initial consistency of the cement slurry added with Comparative Example 1 is relatively high, at about 45Bc. When the thickening time is 50-80 minutes, the consistency increases to about 30Bc, bulging phenomenon occurs, and the thickening time is about 210 minutes. The consistency of the cement slurry added with Comparative Example 2 is stable, and the temperature line begins to fluctuate greatly at 70 minutes, core phenomenon occurs, and the thickening time is about 220 minutes. Figure 1-3 It can be seen that the cement slurry added with Example 1 has good comprehensive performance and no core or bulging occurs.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A high temperature resistant broad spectrum environmentally friendly retarder for cementing, Features: It includes chemically modified lignin sulfonate and a high molecular copolymer, wherein the mass ratio of the chemically modified lignin sulfonate to the high molecular copolymer is 2-5:5-8; Chemically modified lignin sulfonate is prepared by modifying lignin sulfonate using an oxidizing agent and a sulfonating agent. Wherein, the lignin sulfonate includes one of sodium lignin sulfonate and calcium lignin sulfonate. The oxidizing agent includes one or two of hydrogen peroxide, potassium permanganate, and potassium dichromate. The sulfonating agent includes one or more of sulfamic acid, sodium sulfite, carbon disulfide, and methyl bromoacetate. The oxidant and sulfonating agent are 3% to 8% and 30% to 50% of the total mass of lignin sulfonate, respectively; The high molecular copolymer is prepared by free radical aqueous solution polymerization reaction of unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side vinyl monomers after adjusting the pH. The unsaturated sulfonic acid monomers include one or two of styrene sulfonic acid, sodium propylene sulfonate, 2-acrylamide-2-methylpropane sulfonic acid, 2-hydroxy-3-allyl sulfonic acid, and sodium methyl propylene sulfonate. The unsaturated carboxylic acid monomers include one or two of itaconic acid, maleic acid, acrylic acid and fumaric acid. The macrocyclic side vinyl monomers include one or more of N-vinyl pyrrolidone, N-vinyl caprolactam, 1,5-cyclooctadiene-3-ethylene, 4-vinyl cyclohexene, and cyclododecahexaene-1-ethylene. The molar ratio of the unsaturated sulfonic acid monomer, the unsaturated carboxylic acid monomer and the macrocyclic side group vinyl monomer is 4-7:2-4:1-2.

2. A high temperature resistant broad spectrum environmentally friendly retarder for cementing according to claim 1, Features: The initiator of the free radical aqueous solution polymerization reaction is a redox initiator, which includes two of ammonium persulfate, ammonium sulfite, sodium bisulfite and potassium persulfate, and is compounded in a mass ratio of 1:

1.

3. A method for preparing the high temperature resistant broad spectrum environmentally friendly retarder for cementing as claimed in any one of claims 1 to 2, Features: The following steps are included: S1, modifying lignin sulfonate using an oxidant and a sulfonating agent to obtain chemically modified lignin sulfonate; S2, adjusting the pH of unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side-group vinyl monomers, and preparing a high molecular copolymer by free radical aqueous solution polymerization; S3. The chemically modified lignin sulfonate in S1 and the high molecular copolymer in S2 are mixed in a mass ratio of 2-5:5-8 to obtain a high temperature resistant retarder.

4. The method for preparing a high temperature resistant broad spectrum environmentally friendly retarder for cementing according to claim 3, Features: Step S1 comprises, S1.

1. Add lignin sulfonate into a three-necked flask, add deionized water and stir to dissolve to obtain a lignin sulfonate solution, the mass concentration of the lignin sulfonate solution is 25%~35%; S1.2, add 3% to 8% of the total mass of lignin sulfonate oxidant to the three-necked flask in S1.1, raise the temperature to 80°C, and react for 3 hours; S1.3, add 30% to 50% of the total mass of lignin sulfonate sulfonating agent and 5% to 20% of formaldehyde to the three-necked flask in S1.2, adjust the pH of the solution to 8 to 9 with a pH adjuster, heat to 90°C, react for 5 hours, and cool to obtain a chemically modified lignin sulfonate aqueous solution; S1.4, removing water from the chemically modified lignin sulfonate aqueous solution, drying it, and grinding it into powder to obtain chemically modified lignin sulfonate.

5. The method for preparing a high temperature resistant broad spectrum environmentally friendly retarder for cementing according to claim 4, Features: The pH regulator in S1.3 is sodium hydroxide.

6. The method for preparing a high temperature resistant broad spectrum environmentally friendly retarder for cementing according to claim 3, Features: Step S2 comprises, S2.

1. Dissolve unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side-group vinyl monomers in deionized water at a molar ratio of 4-7:2-4:1-2 to obtain a mixed solution, wherein the total mass concentration of the unsaturated sulfonic acid monomers, unsaturated carboxylic acid monomers and macrocyclic side-group vinyl monomers in the mixed solution is 20%-25%; S2.2, adjusting the pH value of the mixed solution in S2.1 to 2-3 to obtain an acidic mixed solution, and then heating it to 60-70°C; S2.3, add a redox initiator dropwise to the acidic mixed solution of S2.2, wherein the amount of the redox initiator is 0.5% to 1% of the total mass of the unsaturated sulfonic acid monomer, the unsaturated carboxylic acid monomer and the macrocyclic side vinyl monomer, the dripping speed is 1 drop per 3 to 4 seconds, and the reaction is carried out at a constant temperature for 4 hours; S2.

4. Remove water from the solution after the reaction in S2.3, dry it, grind it into powder, and obtain a high molecular copolymer.

7. Use of the high temperature resistant broad spectrum environmentally friendly retarder for cementing as claimed in any one of claims 1 to 2, Features: Used in oil well cement.

Images