A Polymer Retarder for Low-Temperature Cementing Sulfoaluminate Cement and Its Preparation Method

Abstract

The present invention discloses a polymer retarder for low-temperature well cementing sulfoaluminate cement and a preparation method thereof. The polymer retarder comprises 30 to 50 parts of N-(hydroxymethyl)acrylamide monomer, 25 to 35 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer, 15 to 25 parts of isopropenylboronic acid monomer, 5 to 10 parts of isopropenylphosphonic acid monomer, 1 to 3 parts of initiator, and 2 to 5 parts of chain transfer agent. The structural units of the polymer retarder comprise a random copolymer having a number average molecular weight of 10,000 to 50,000 and the general formula I, II, III, and IV. The polymer retarder of the present invention has a good linear retarding effect on sulfoaluminate cement, that is, its effect on delaying the low-temperature thickening time of sulfoaluminate cement increases linearly with increasing dosage, without dosage inversion or dosage sensitivity issues. In addition, the polymer retarder does not affect the early and late strengths of sulfoaluminate cement.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer retarders for sulphoaluminate cement, and particularly relates to a polymer retarder for low-temperature well cementing sulphoaluminate cement and a preparation method thereof. Background Art

[0002] With the continuous growth of China's social economy, the demand for oil and gas resources is also increasing. Shallow oil and gas resources on land have been developed to the point of exhaustion, and deep oil and gas reserves are limited and expensive to extract, making it difficult to meet the energy needs of today's social development. However, China's offshore oil and gas reserves are vast, with huge potential for exploration and development. Vigorously exploring and developing offshore oil and gas resources will help fill the gap in oil and gas resources.

[0003] China's offshore oil resource development strategy is currently shifting from shallow waters to deep waters. Deepwater cementing, particularly surface cementing, faces a challenging low-temperature environment during exploration and development. Low temperatures have become a major operational challenge for deepwater cementing. Cementing slurries experience severe setbacks in low-temperature environments, resulting in slow strength development and poor cementitious properties in the annulus cement, weakened anti-channeling capabilities, and a high risk of oil, gas, and water channeling in the annulus. This not only severely impacts cementing quality but also increases the costs of offshore cementing and other subsequent operations, making it difficult to ensure the efficient and safe extraction of deepwater oil and gas resources. Currently, deepwater cementing slurries are primarily based on silicate cement systems. Even with the addition of large amounts of low-temperature early-strengthening agents, these systems still struggle to meet the strength requirements for deepwater, low-temperature cementing. To address these challenges, sulfoaluminate cement, with its rapid hardening and early-strengthening properties, can be used as a new type of deepwater, low-temperature cementing cement to address the challenges faced by existing deepwater, low-temperature cementing slurry systems.

[0004] Sulphoaluminate cement is a fast-hardening, early-strengthening specialty cement with advantages such as low alkalinity, rapid hydration and hardening, resistance to CO2 corrosion, and high early strength. Sulphoaluminate cement sets quickly; pure sulfate cement sets in just 10 minutes at room temperature and quickly forms a cementitious structure with sufficient strength. To ensure safe cementing operations, the retarding time of sulphoaluminate cement must be appropriately adjusted. However, existing oil well cement retarders, primarily AMPS polymers, are primarily suitable for use in Portland cement systems and are less effective in retarding sulphoaluminate cement systems. However, boric acid and hydroxycarboxylic acid retarders commonly used in sulphoaluminate cement also present numerous challenges. Boric acid's retarding effect on sulfate cement is unstable; low dosages have no effect, while high dosages can cause severe retarding and compromise its early strength. Hydroxycarboxylic acid retarders, such as citric acid and sodium gluconate, are sensitive to dosage and, at high dosages, can even accelerate setting, significantly impacting both the early and later strengths of sulphoaluminate cement.

[0005] To address the adverse effects of existing retarders such as boric acid and hydroxycarboxylic acid on the performance of sulphoaluminate cement, the polymer retarder of the present invention can effectively delay the thickening time of sulphoaluminate cement, and its delaying effect shows a good linear relationship with its added dosage. In addition, the polymer retarder has good compatibility with the fluid loss additive and dispersant used in cement cementing. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a polymer retarder for low-temperature cementing of sulphoaluminate cement, so as to reduce the adverse effects on deepwater cementing operations caused by the unstable retarding effect of existing retarders when sulphoaluminate cement is used in low-temperature cementing environments, thereby achieving safe cementing construction of low-temperature deepwater cement slurry, thereby ensuring the efficient and safe exploitation of oil and gas resources in deepwater areas and meeting the country's demand for deepwater oil and gas resources.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A polymer retarder for low-temperature well cementing sulphoaluminate cement comprises the following components in parts by weight:

[0009]

[0010] The present invention uses N-(hydroxymethyl)acrylamide, 3-allyloxy-2-hydroxy-1-propanesulfonate, isopropenylboric acid and isopropenylphosphonic acid as reaction monomers, adds initiators and chain transfer agents, and prepares a polymer retarder for sulfoaluminate cement through aqueous solution free radical polymerization. The polymer retarder contains a large number of polar groups such as -OH and -SO3M, which have a good adsorption effect on sulfoaluminate cement. After the polymer retarder is adsorbed, it can form a retarder film layer on the surface of cement particles that inhibits hydration, thereby hindering the hydration of sulfoaluminate cement. However, as the hydration reaction proceeds, the retarder film will break under the action of the internal and external osmotic pressure difference, so that the hydration reaction of sulfoaluminate cement proceeds normally, and therefore does not affect its early strength. Furthermore, the polymer retarder contains -B(OH)2 and -PO(OH)2 groups that have a good retarding effect on sulfoaluminate, which can react with Ca in the liquid phase. 2+The complex forms a thick, amorphous complex film on the surface of the sulfoaluminate cement, thereby delaying the hydration of the sulfoaluminate cement. As the hydration reaction proceeds, the complex film is destroyed, and the hydration continues with signs of delayed acceleration. Therefore, the early strength of the sulfoaluminate cement is not affected. In the present invention, the N-(hydroxymethyl)acrylamide monomer is 30 to 50 parts; for example, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 parts, 49 parts, and 50 parts.

[0011] The amount of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer is 25 to 35 parts; for example, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, and 35 parts.

[0012] The amount of the isopropenyl boronic acid monomer is 15 to 25 parts; for example, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, and 25 parts.

[0013] The amount of the isopropenylphosphonic acid monomer is 5 to 10 parts; for example, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, and 10 parts.

[0014] The initiator is 1 to 3 parts; for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts.

[0015] The chain transfer agent is 2 to 5 parts; for example, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, and 5 parts.

[0016] In some embodiments of the present invention, the polymer retarder includes the following components in parts by weight:

[0017]

[0018]

[0019] Furthermore, the structural unit composition of the polymer retarder comprises a random copolymer of formula I, formula II, formula III and formula IV and a number average molecular weight of 10,000 to 50,000;

[0020]

[0021] Furthermore, in the structural units of the polymer retarder, the mass percentages of the random copolymers are: formula I = 30-50%, formula II = 25-35%, formula III = 15-25%, and formula IV = 5-10%.

[0022] The mass percentage of the random copolymer represented by Formula I is 30-50%, for example, 30%, 31%, 32%, 333%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, and 50%.

[0023] The mass percentage of the random copolymer represented by Formula II is 25-35%, for example, 25%, 26%, 27%, 28%, 29%, 30%, 21%, 32%, 33%, 34%, 35%.

[0024] The mass percentage of the random copolymer represented by formula III is 15-25%, for example, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%.

[0025] The mass percentage of the random copolymer represented by Formula IV is 5-10%, for example, 5%, 6%, 7%, 8%, 9%, or 10%. Furthermore, the initiator is a peroxide or a mixture of several peroxides, and the peroxides include but are not limited to potassium persulfate, sodium persulfate, and ammonium persulfate.

[0026] Furthermore, the chain transfer agent is one or a mixture of isopropyl alcohol, sodium bisulfite, and sodium hypophosphite.

[0027] The present invention also provides a method for preparing the polymer retarder for low-temperature cementing sulphoaluminate cement, the preparation method comprising the following steps:

[0028] Step 1: Add water to N-(hydroxymethyl)acrylamide monomer and allyloxy-2-hydroxy-1-propanesulfonate monomer and mix thoroughly and evenly to obtain a first mixed solution; preferably, by weight, weigh 30 to 50 parts of N-(hydroxymethyl)acrylamide monomer and 25 to 35 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer, add them to 25 to 50 parts of water, and mix thoroughly and evenly to obtain a first mixed solution; Step 2: Evenly disperse isopropenylphosphonic acid monomer and isopropenylboric acid monomer in water to obtain a second mixed solution; preferably, by weight, weigh 15 to 25 parts of isopropenylphosphonic acid monomer and 5 to 10 parts of isopropenylboric acid monomer and evenly disperse them in 70 to 85 parts of water to obtain a second mixed solution;

[0029] Step 3: adding an initiator to water to obtain a third mixed solution; preferably, by weight, 1 to 3 parts of the initiator are added to 22 to 24 parts of water to obtain the third mixed solution;

[0030] Step 4: adding a chain transfer agent to water to obtain a fourth mixed solution; preferably, by weight, 2 to 5 parts of the chain transfer agent are added to 20 to 22 parts of water to obtain the fourth mixed solution;

[0031] Step 5: Under a protective atmosphere, uniformly mix the first mixed liquid and the second mixed liquid to obtain a fifth mixed liquid; transfer the fifth mixed liquid to a reactor and heat it to a set temperature; and sequentially add the third mixed liquid and the fourth mixed liquid dropwise to the fifth mixed liquid to obtain a sixth mixed liquid; preferably, the protective atmosphere is an inert gas or nitrogen;

[0032] Step 6: keeping the sixth mixed solution at the set temperature of step 5 and stirring, then cooling it naturally, and keeping it at the cooled temperature and stirring to obtain a seventh mixed solution;

[0033] Step 7: washing, purifying and drying the seventh mixed liquid to obtain the polymer retarder;

[0034] Preferably, steps 1, 2, 3, and 4 are performed at room temperature;

[0035] Preferably, in step 5, the set temperature of the heating in the reactor is 80-88°C; more preferably, the set temperature is 85°C;

[0036] Preferably, in step 6, the sixth mixed solution is kept at 80-88° C. for 3-5 hours, then naturally cooled to 45-50° C., and kept at 45-50° C. for 2-3 hours, and then the reaction solution is taken out from the reactor to obtain the seventh mixed solution; more preferably, the natural cooling temperature is 50° C.;

[0037] Preferably, in step 7, the seventh mixed solution is washed and purified multiple times with anhydrous acetone, with 100 parts of anhydrous acetone added each time, and then the anhydrous acetone is filtered off;

[0038] Preferably, in step 7, the seventh mixed liquid is dried by vacuum freezing, the vacuum freezing temperature is -10°C to 15°C, more preferably -10°C; the vacuum freezing time is 10 to 12 hours, more preferably 12 hours.

[0039] Furthermore, in step 5, the dropping speed of the third mixed liquid and the fourth mixed liquid is 8 to 15 drops / min; preferably, the dropping speed is 10 drops / min.

[0040] Furthermore, the step 5 further comprises adjusting the pH of the fifth mixed solution obtained by mixing to 6-7 using an alkaline solution; preferably, the alkaline solution is an inorganic alkaline solution, more preferably a NaOH solution, and further preferably, the concentration of the NaOH solution is 20 wt.%.

[0041] Furthermore, in step 6, when the sixth mixed liquid is kept warm for the first time, the stirring speed is 300 r / min; when the sixth mixed liquid is kept warm for the second time, the stirring speed is 200 r / min.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] Compared with existing sulfoaluminate cement retarders, the polymer retarder of the present invention has a good linear retarding effect on sulfoaluminate cement, that is, its delaying effect on the low-temperature thickening time of sulfoaluminate cement increases linearly with increasing dosage, and there is no dosage inversion or dosage sensitivity problem. In addition, the polymer retarder does not affect the early strength and late strength of sulfoaluminate cement.

[0044] The polymer retarder of the invention has a simple preparation process and a wide source of raw materials, and has a good linear retarding effect on sulphoaluminate cement when added in a small amount.

[0045] The polymer retarder of the present invention has good compatibility with cementing additives such as fluid loss additives and dispersants. The use of these additives can form a set of deepwater low-temperature cementing slurries with good comprehensive working performance, improve the quality of deepwater low-temperature cementing, and thus improve the efficient and safe exploitation of deepwater oil and gas resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a structural unit diagram of the polymer retarder (random multipolymer) of the present invention.

[0047] Figure 2 This is an infrared spectrum of the molecular structure of the polymer retarder (random multipolymer) of the present invention. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] Example 1

[0050] As a preferred embodiment of the present invention, a polymer retarder for low-temperature cementing sulphoaluminate cement disclosed in this embodiment includes the following components in parts by weight:

[0051]

[0052] In this embodiment, a method for preparing a polymer retarder for low-temperature cementing sulphoaluminate cement is as follows:

[0053] Step 1: Weigh 50 parts by weight of N-(hydroxymethyl)acrylamide monomer and 25 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer, add them to 25 parts of water, and mix thoroughly to obtain a first mixed solution;

[0054] Step 2: Weigh 15 parts by weight of isopropenyl boronic acid monomer and 5 parts by weight of isopropenyl phosphonic acid monomer, and evenly disperse them in 80 parts of water to obtain a second mixed solution;

[0055] Step 3: Weigh 3 parts of ammonium persulfate by weight and add them to 24 parts of water to obtain a third mixed solution;

[0056] Step 4: Weigh 2 parts of isopropyl alcohol by weight and add them to 22 parts of water to obtain a fourth mixed solution;

[0057] Step 5, uniformly mixing the first mixed liquid and the second mixed liquid to obtain a fifth mixed liquid; after the fifth mixed liquid is transferred to a 20% by mass percentage NaOH solution and adjusted to 6-7, it is transferred to a reactor with a heating and stirring device, nitrogen is purged and oxygen is maintained in a nitrogen atmosphere, the stirring speed is set to 300r / min, the heating is turned on, and the fifth mixed liquid is heated to 85°C. After that, the third mixed liquid is added dropwise through a constant pressure funnel device at a dropping rate of 10 drops / min. After the addition is complete, the fourth mixed liquid is added dropwise using the same constant pressure funnel device at a dropping rate of 10 drops / min. After the third and fourth mixed liquids are added dropwise, a sixth mixed liquid is obtained;

[0058] Step 6: keeping the sixth mixed solution at 85° C. for 1 to 2 hours with a stirring speed of 300 r / min, then naturally cooling it to 50° C. and keeping it at this temperature for 1 to 2 hours with a stirring speed of 200 r / min. The reaction solution was removed from the reactor to obtain a seventh mixed solution.

[0059] Step 7: Add 100 parts of anhydrous acetone to the seventh mixed solution, wash and purify it multiple times, and filter out the anhydrous acetone to obtain an off-white viscous substance; after freeze-drying, the polymer retarder is obtained.

[0060] Example 2

[0061] As a preferred embodiment of the present invention, a polymer retarder for low-temperature cementing sulphoaluminate cement disclosed in this embodiment includes the following components in parts by weight:

[0062]

[0063] In this embodiment, a method for preparing a polymer retarder for low-temperature cementing sulphoaluminate cement is as follows:

[0064] Step 1: Weigh 30 parts by weight of N-(hydroxymethyl)acrylamide monomer and 35 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer, add them to 45 parts of water, and mix thoroughly to obtain a first mixed solution;

[0065] Step 2: Weigh 20 parts by weight of isopropenyl boronic acid monomer and 10 parts by weight of isopropenyl phosphonic acid monomer, and evenly disperse them in 85 parts of water to obtain a second mixed solution;

[0066] Step 3: Weigh 1 part of ammonium persulfate by weight and add it to 22 parts of water to obtain a third mixed solution;

[0067] Step 4: Weigh 4 parts of isopropyl alcohol by weight and add them to 20 parts of water to obtain a fourth mixed solution;

[0068] Step 5, uniformly mixing the first mixed liquid and the second mixed liquid to obtain a fifth mixed liquid; after the fifth mixed liquid is transferred to a 20% by mass percentage NaOH solution and adjusted to 6-7, it is transferred to a reactor with a heating and stirring device, nitrogen is purged and oxygen is maintained in a nitrogen atmosphere, the stirring speed is set to 300r / min, the heating is turned on, and the fifth mixed liquid is heated to 85°C. After that, the third mixed liquid is added dropwise through a constant pressure funnel device at a dropping rate of 10 drops / min. After the addition is complete, the fourth mixed liquid is added dropwise using the same constant pressure funnel device at a dropping rate of 10 drops / min. After the third and fourth mixed liquids are added dropwise, a sixth mixed liquid is obtained;

[0069] Step 6: keeping the sixth mixed solution at 85° C. for 1 to 2 hours with a stirring speed of 300 r / min, then naturally cooling it to 50° C. and keeping it at this temperature for 1 to 2 hours with a stirring speed of 200 r / min. The reaction solution was removed from the reactor to obtain a seventh mixed solution.

[0070] Step 7: Add 100 parts of anhydrous acetone to the seventh mixed solution, wash and purify it multiple times, and filter out the acetone to obtain an off-white viscous substance; after freeze-drying, the polymer retarder is obtained.

[0071] Example 3

[0072] As a preferred embodiment of the present invention, a polymer retarder for low-temperature cementing sulphoaluminate cement disclosed in this embodiment includes the following components in parts by weight:

[0073]

[0074] In this embodiment, a method for preparing a polymer retarder for low-temperature cementing sulphoaluminate cement is as follows:

[0075] Step 1: Weigh 40 parts by weight of N-(hydroxymethyl)acrylamide monomer and 30 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer, add them to 30 parts of water, and mix thoroughly to obtain a first mixed solution;

[0076] Step 2: Weigh 17 parts of isopropenyl boronic acid monomer and 6 parts of isopropenyl phosphonic acid monomer, and evenly disperse them in 70 parts of water to obtain a second mixed solution;

[0077] Step 3: Weigh 2 parts by weight of ammonium persulfate and add them to 23 parts of water to obtain a third mixed solution;

[0078] Step 4: Weigh 5 parts of isopropyl alcohol by weight and add them to 21 parts of water to obtain a fourth mixed solution;

[0079] Step 5, uniformly mixing the first mixed liquid and the second mixed liquid to obtain a fifth mixed liquid; after the fifth mixed liquid is transferred to a 20% by mass percentage NaOH solution and adjusted to 6-7, it is transferred to a reactor with a heating and stirring device, nitrogen is purged and oxygen is maintained in a nitrogen atmosphere, the stirring speed is set to 300r / min, the heating is turned on, and the fifth mixed liquid is heated to 85°C. After that, the third mixed liquid is added dropwise through a constant pressure funnel device at a dropping rate of 10 drops / min. After the addition is complete, the fourth mixed liquid is added dropwise using the same constant pressure funnel device at a dropping rate of 10 drops / min. After the third and fourth mixed liquids are added dropwise, a sixth mixed liquid is obtained;

[0080] Step 6: keeping the sixth mixed solution at 85° C. for 1 to 2 hours with a stirring speed of 300 r / min, then naturally cooling it to 50° C. and keeping it at this temperature for 1 to 2 hours with a stirring speed of 200 r / min. The reaction solution was removed from the reactor to obtain a seventh mixed solution.

[0081] Step 7: Add 100 parts of anhydrous acetone to the seventh mixed solution, wash and purify it multiple times, and filter out the acetone to obtain an off-white viscous substance; after freeze-drying, the polymer retarder is obtained.

[0082] Example 4

[0083] As a preferred embodiment of the present invention, a polymer retarder for low-temperature cementing sulphoaluminate cement disclosed in this embodiment includes the following components in parts by weight:

[0084]

[0085]

[0086] In this embodiment, a method for preparing a polymer retarder for low-temperature cementing sulphoaluminate cement is as follows:

[0087] Step 1: Weigh 33 parts of N-(hydroxymethyl)acrylamide monomer and 28 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer, add them to 50 parts of water, and mix thoroughly to obtain a first mixed solution;

[0088] Step 2: Weigh 25 parts by weight of isopropenyl boronic acid monomer and 8 parts by weight of isopropenyl phosphonic acid monomer, and evenly disperse them in 75 parts of water to obtain a second mixed solution;

[0089] Step 3: Weigh 3 parts by weight of ammonium persulfate and add them to 22 parts of water to obtain a third mixed solution;

[0090] Step 4: Weigh 3 parts of isopropyl alcohol by weight and add them to 21 parts of water to obtain a fourth mixed solution;

[0091] Step 5, uniformly mixing the first mixed liquid and the second mixed liquid to obtain a fifth mixed liquid; after the fifth mixed liquid is transferred to a 20% by mass percentage NaOH solution and adjusted to 6-7, it is transferred to a reactor with a heating and stirring device, nitrogen is purged and oxygen is maintained in a nitrogen atmosphere, the stirring speed is set to 300r / min, the heating is turned on, and the fifth mixed liquid is heated to 85°C. After that, the third mixed liquid is added dropwise through a constant pressure funnel device at a dropping rate of 10 drops / min. After the addition is complete, the fourth mixed liquid is added dropwise using the same constant pressure funnel device at a dropping rate of 10 drops / min. After the third and fourth mixed liquids are added dropwise, a sixth mixed liquid is obtained;

[0092] Step 6: keeping the sixth mixed solution at 85° C. for 1 to 2 hours with a stirring speed of 300 r / min, then naturally cooling it to 50° C. and keeping it at this temperature for 1 to 2 hours with a stirring speed of 200 r / min. The reaction solution was removed from the reactor to obtain a seventh mixed solution.

[0093] Step 7: Add 100 parts of anhydrous acetone to the seventh mixed solution, wash and purify it multiple times, and filter out the acetone to obtain an off-white viscous substance; after freeze-drying, the polymer retarder is obtained.

[0094] Test Example 1

[0095] The polymer retarders (random multi-component copolymers) obtained in Examples 1 to 4 have a number average molecular weight of 10,000 to 50,000. The structural units in the random multi-component copolymers are as follows: Figure 1The random copolymers of formula I, formula II, formula III and formula IV shown in FIG. 1, wherein the infrared spectrum of the retarder prepared in Example 1 is as follows: Figure 2 shown.

[0096] The structural unit shown in formula I is Figure 2 ) are characterized as follows: 3450cm in the infrared spectrum -1 The stretching vibration absorption peaks at 2967 and 2857 cm are attributed to the hydroxyl (—OH) in the N-(hydroxymethyl) acrylamide monomer. -1 It is the stretching vibration absorption peak of methylene C—H, 1760~1650cm -1 The peak is attributed to the C=O bond stretching vibration absorption peak, 1650~1500cm -1 The C-N stretching vibration absorption peak and N-H bending vibration absorption peak of -CONH- in N-(hydroxymethyl)acrylamide monomer are located at 1311 cm -1 The absorption peak is the C—H bending vibration.

[0097] The structural unit shown in formula II is Figure 2 ) are characterized as follows: 3450cm -1 The stretching vibration absorption peaks at 2967 and 2857 cm-1 can be attributed to the hydroxyl (—OH) in the 3-allyloxy-2-hydroxy-1-propanesulfonate monomer. -1 It is the stretching vibration absorption peak of methylene C—H, 1311 cm -1 The C-H bending vibration absorption peak is at 1263 cm in the infrared spectrum. -1 The peak at 1039cm-1 is the stretching vibration absorption peak of C—O—C in 3-allyloxy-2-hydroxy-1-propanesulfonate monomer, the peak at 873cm-1 is attributed to the stretching vibration characteristic absorption peak of sulfonic acid group-SO3M, and the peak at 1039cm-1 is attributed to the stretching vibration characteristic absorption peak of sulfonic acid group-SO3M. -1 The C—O—C bending vibration absorption peak is at 617cm -1 The weak peak at is the O—S stretching vibration absorption peak.

[0098] The structural unit shown in formula III is Figure 2 ) are characterized as follows: 3450cm in the infrared spectrum -1 The stretching vibration absorption peaks at 2967 and 2857 cm-1 can be attributed to the hydroxyl (—OH) in isopropenylboronic acid. -1 It is the stretching vibration absorption peak of methyl or methylene C—H, 1405cm -1 The antisymmetric deformation vibration absorption peak of -CH3 is 1311cm -1 The stretching vibration absorption peak of B-O bond is at 1015cm -1 The point is the B-O-H stretching vibration absorption peak.

[0099] The structural unit shown in formula IV is Figure 2 ) are characterized as follows: 3450cm in the infrared spectrum -1 The stretching vibration absorption peaks at 2967 and 2857 cm-1 can be attributed to the hydroxyl (—OH) in isopropenylphosphonic acid. -1 It is the stretching vibration absorption peak of methyl or methylene C—H, 1405cm -1 The antisymmetric deformation vibration absorption peak of -CH3 is 1263cm -1 、1205cm -1 The stretching vibration absorption peak of P=O bond is 1134cm -1 The weak peak is the P—O stretching vibration absorption peak.

[0100] The polymer retarder obtained in Examples 1-4 was added to cement slurries prepared under the same conditions to obtain experimental groups corresponding to each example. Experiments were conducted using the following formulation: sulphoaluminate cement (based on 100 wt.% of sulphoaluminate cement) + 0.3 wt.% of a polycarboxylic acid dispersant + 0-0.3 wt.% of a polymer retarder + 3 wt.% of an acrylamide-based G33S fluid loss additive + 0.3 wt.% of a dimethyl silicone oil-based defoamer + 44 wt.% of water. (This cementing slurry formulation is not limited to the aforementioned cementing admixtures.)

[0101] A control group and a blank group were set up at the same time. The control group used a commercially available boric acid retarder to replace the polymer retarder of the present invention, while the blank group did not add any retarder. The other proportions and conditions were the same as the above formula.

[0102] Low-temperature cementing slurries were prepared according to GB / T 19139-2012 Test Methods for Oil Well Cement. The thickening and engineering properties of the low-temperature cementing slurries in the control and examples were tested in accordance with SY / T 6544-2017 Performance Requirements for Oil Well Cement Slurries. The experimental results are shown in Table 1.

[0103] Table 1 Comparison of experimental results

[0104]

[0105] Note: “-” in the blank group means no retarder was added.

[0106] The results in Table 1 show that without a retarder, sulfoaluminate cement has a short low-temperature thickening time, failing to meet the safe cementing construction time requirements. Adding a boric acid retarder, commonly used in sulfoaluminate cement, results in an unstable retarding effect, which affects the early strength of the cement paste (low early strength). However, the polymer retarder prepared in the present invention exhibits an excellent low-temperature linear retarding effect on sulfoaluminate cement. The thickening time increases linearly with increasing polymer retarder addition, and has no adverse effects on the performance of the sulfoaluminate cement, including early strength, water loss, and fluidity.

[0107] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention and are intended to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features therein may be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or refinements made to the main design concept and spirit of the present invention that have no substantive significance, provided that the technical problems they solve are still consistent with those of the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields should also be included in the patent protection scope of the present invention.

Claims

1. A polymer retarder for low-temperature cementing sulphoaluminate cement, characterized in that: The raw materials for its preparation include the following components in parts by weight: 30-50 parts of N-(hydroxymethyl)acrylamide monomer; 25-35 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer; 15-25 parts of isopropenyl boronic acid monomer; 5-10 parts of isopropenylphosphonic acid monomer; 1~3 parts of initiator; 2~5 parts of chain transfer agent.

2. A polymer retarder for low-temperature cementing sulphoaluminate cement according to claim 1, characterized in that: The raw materials for its preparation include the following components in parts by weight: 35-45 parts of N-(hydroxymethyl)acrylamide monomer; 30-35 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate monomer; 20-25 parts of isopropenyl boronic acid monomer; 5-8 parts of isopropenylphosphonic acid monomer; 2~3 parts of initiator; 2~3 parts of chain transfer agent.

3. A polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 1 or 2, characterized in that: The polymer retarder is a random copolymer with a number average molecular weight of 10,000 to 50,000.

4. A polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 1 or 2, characterized in that: The initiator is one or a mixture of several peroxides.

5. A polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 1 or 2, characterized in that: The chain transfer agent is one or a mixture of isopropyl alcohol, sodium bisulfite, and sodium hypophosphite.

6. A method for preparing a polymer retarder for low-temperature cementing sulphoaluminate cement, characterized in that: The preparation method is applied to the polymer retarder according to any one of claims 1 to 5, and the preparation method comprises: Step 1: Weigh 30-50 parts of N-(hydroxymethyl)acrylamide monomer and 25-35 parts of allyloxy-2-hydroxy-1-propanesulfonate monomer in parts by weight, add them to 25-50 parts of water, and mix thoroughly to obtain a first mixed solution; Step 2: Weigh 15 to 25 parts of isopropenylphosphonic acid monomer and 5 to 10 parts of isopropenylboronic acid monomer, and uniformly disperse them in 70 to 85 parts of water to obtain a second mixed solution; Step 3: Weigh 1 to 3 parts of initiator by weight and add them to 22 to 24 parts of water to obtain a third mixed solution; Step 4: Weigh 2 to 5 parts by weight of a chain transfer agent and add them to 20 to 22 parts of water to obtain a fourth mixed solution; Step 5: Select a reactor of appropriate size, introduce nitrogen to remove oxygen, maintain a nitrogen atmosphere, and uniformly mix the first mixed solution with the second mixed solution to obtain a fifth mixed solution; transfer the fifth mixed solution to a reactor, heat it to a set temperature, and sequentially add the third mixed solution and the fourth mixed solution dropwise to the fifth mixed solution using a constant pressure funnel apparatus to obtain a sixth mixed solution; Step 6: keeping the sixth mixed solution at the set temperature of step 5 and stirring, then cooling it naturally, and keeping it at the cooled temperature and stirring to obtain a seventh mixed solution; Step 7: washing, purifying and drying the seventh mixed liquid to obtain the polymer retarder.

7. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 6, characterized in that: In step 5, the dropping speed of the third mixed liquid and the fourth mixed liquid is 8 to 15 drops / min.

8. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 6, characterized in that: The step 5 further includes adjusting the pH of the fifth mixed solution obtained by mixing to 6-7 using a NaOH solution; the concentration of the NaOH solution is 20%.

9. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 6, characterized in that: In step 6, when the sixth mixed solution is kept warm for the first time, the stirring speed is 300 r / min; when the sixth mixed solution is kept warm for the second time, the stirring speed is 200 r / min.

10. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 6, characterized in that: Steps 1, 2, 3 and 4 are carried out at room temperature.

11. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 6, characterized in that: In step 5, the set temperature of the heating in the reactor is 80-88°C.

12. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 11, characterized in that: Set the temperature to 85°C.

13. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 6, characterized in that: In step 6, the sixth mixed solution is kept at 80-88° C. for 3-5 hours, then naturally cooled to 45-50° C., and kept at 45-50° C. for 2-3 hours, and then the reaction solution is taken out from the reactor to obtain the seventh mixed solution.

14. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 13, characterized in that: The natural cooling temperature is 50℃.

15. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 6, characterized in that: In step 7, the seventh mixed solution is washed and purified multiple times with anhydrous acetone, with 100 parts of anhydrous acetone added each time, and then the anhydrous acetone is filtered off.

16. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 6, characterized in that: In step 7, the seventh mixed liquid is dried by vacuum freezing, the vacuum freezing temperature is -10°C to 15°C, and the vacuum freezing time is 10 to 12 hours.

17. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 16, characterized in that: The vacuum freezing temperature is -10°C and the vacuum freezing time is 12h.

18. The method for preparing a polymer retarder for low-temperature well cementing sulphoaluminate cement according to claim 7, characterized in that: The dropping speed is 10 drops / min.

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