A high stability retarder for oil well cement

Abstract

The invention relates to the technical field of cement additives, and proposes a high-stability retarder for oil well cement, comprising the following raw materials in parts by weight: 3-5 parts of hydroxycarboxylate, 12-15 parts of polysaccharide, 0.05-0.8 parts of 4-imidazole acrylic acid, 2-3 parts of hydrochloric acid, 0.1-0.8 parts of succinaldehyde, and 70-80 parts of deionized water. Through the above technical scheme, the problem of "core encapsulation" of cement retarders at high temperatures in the prior art is solved, thereby causing low retarding property.

Description

Technical Field

[0001] The invention relates to the technical field of cement additives, and in particular to a high-stability retarder for oil well cement. Background Art

[0002] Cement retarder is a cement admixture, commonly used in cement slurry used in oil well cementing operations. In oil well cementing operations, cement slurry needs to be delivered to the action position by pump to achieve the purpose of isolating oil, gas, water, protecting the formation layer and supporting the protective casing. The cement slurry needs to maintain fluidity before being delivered to the required position, but as the cement hydration reaction proceeds, after reaching a certain degree of hydration, the cement will lose fluidity and cannot be used for construction operations. Therefore, a retarder should be added to the cement slurry to ensure that the cement slurry can operate normally.

[0003] During the exploitation of oil and gas fields, as the depth of the well increases, the temperature at the bottom of the well continues to increase, and the hydration rate of cement also accelerates. This requires the retarder to be able to slow down the hydration rate of cement slurry at high temperature and prolong the thickening time. However, the commonly used high-temperature retarders will have a "core-wrapping" phenomenon above 120°C, which limits their application. Patent CN111662409B, a high-temperature oil well cement retarder capable of inhibiting abnormal gelation and a preparation method, discloses a high-temperature oil well cement retarder capable of inhibiting abnormal gelation, but the normal working temperature only reaches 150°C. Once the temperature rises, the "core-wrapping" and "bulging" phenomena will still occur, thereby affecting the comprehensive performance of the cement slurry. Summary of the invention

[0004] The present invention provides a high-stability retarder for oil well cement, which solves the problem in the related art that the cement retarder has a "core" phenomenon at high temperature, thereby causing low retarding property.

[0005] The technical solution of the present invention is as follows:

[0006] The invention provides a high-stability retarder for oil well cement, which comprises the following raw materials in parts by weight: 3-5 parts of hydroxycarboxylate, 12-15 parts of polysaccharide, 0.05-0.8 parts of 4-imidazole acrylic acid, 2-3 parts of hydrochloric acid, 0.1-0.8 parts of succinaldehyde and 70-80 parts of deionized water.

[0007] As a further technical solution, the mass of the succinaldehyde is 2% to 3% of the mass of the hydroxycarboxylate and the polysaccharide.

[0008] As a further technical solution, the mass of the succinaldehyde is 2.6% of the mass of the hydroxycarboxylate and the polysaccharide.

[0009] As a further technical solution, the mass of the 4-imidazole acrylic acid is 1% to 3% of the mass of the hydroxycarboxylate and the polysaccharide.

[0010] As a further technical solution, the mass of the 4-imidazole acrylic acid is 2.1% of the mass of the hydroxycarboxylate and the polysaccharide.

[0011] As a further technical solution, the mass concentration of the hydrochloric acid is 30%~35%.

[0012] As a further technical solution, the hydroxycarboxylate is one or both of sodium gluconate and sodium glucoheptonate dihydrate.

[0013] As a further technical solution, the polysaccharide is one or more of Platycodon grandiflorum polysaccharide, white dextrin, and inulin.

[0014] The present invention also includes a method for preparing a high-stability retarder for oil well cement, which comprises the following steps: uniformly mixing raw material components, reacting, and obtaining the retarder.

[0015] As a further technical solution, the reaction temperature is 85-95° C. and the reaction time is 2-3 h.

[0016] The present invention also includes the use of a high-stability retarder for oil well cement in high-temperature oil well cement.

[0017] The working principle and beneficial effects of the present invention are:

[0018] 1. In the present invention, hydroxycarboxylates and polysaccharides are used as base materials of the retarder, which can chelate cations in cement to generate stable chelates, and adsorb on the surface of cement particles to prevent cement particles from forming more stable crystals, thereby achieving the effect of inhibiting hydration and prolonging thickening time. Succinaldehyde can undergo cross-linking reaction with hydroxycarboxylates and polysaccharides under the catalysis of hydrochloric acid to form a cross-linked network structure, thereby improving the compressive strength of the retarder at high temperature and further enhancing the retarding property. Adding 4-imidazole acrylic acid to the retarder can not only synergize with hydroxycarboxylates and polysaccharides to chelate cations in cement and further improve the retarding property, but can also further undergo condensation reaction and form hydrogen bonds with hydroxycarboxylates and polysaccharides to form a more dense cross-linked network structure, thereby further improving the compressive strength of the retarder at high temperature and further improving the retarding property, and solving the problem of the "core-wrapping" phenomenon occurring at high temperature. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the following examples and comparative examples,

[0021] The model number of sodium glucose heptanate dihydrate is 20230316;

[0022] The item number of Platycodon grandiflorum polysaccharide is 034, and the manufacturer is Shaanxi Fuerbang Biotechnology Co., Ltd.;

[0023] The model of white dextrin is LA-7Q, and the manufacturer is Shandong Liang New Materials Technology Co., Ltd.;

[0024] The product number of inulin is 12536, and the manufacturer is Shaanxi Lvlai Biotechnology Co., Ltd.

[0025] Example 1

[0026] A method for preparing a high-stability retarder for oil well cement comprises the following steps:

[0027] 3 parts of sodium gluconate, 12 parts of platycodon polysaccharide, 0.1 parts of 4-imidazole acrylic acid, 2 parts of hydrochloric acid, 0.2 parts of succinaldehyde and 70 parts of deionized water were mixed evenly, heated to 85°C under stirring, and reacted for 3 hours to obtain a retarder; the mass concentration of hydrochloric acid was 30%.

[0028] Example 2

[0029] A method for preparing a high-stability retarder for oil well cement comprises the following steps:

[0030] 4 parts of sodium glucoheptonate dihydrate, 13 parts of white dextrin, 0.36 parts of 4-imidazole acrylic acid, 2.5 parts of hydrochloric acid, 0.45 parts of succinaldehyde and 75 parts of deionized water were mixed evenly, heated to 90° C. under stirring, and reacted for 2.5 hours to obtain a retarder; wherein the mass concentration of the hydrochloric acid was 33%.

[0031] Example 3

[0032] A method for preparing a high-stability retarder for oil well cement comprises the following steps:

[0033] 5 parts of sodium gluconate, 15 parts of inulin, 0.5 parts of 4-imidazole acrylic acid, 3 parts of hydrochloric acid, 0.5 parts of succinaldehyde and 80 parts of deionized water were mixed evenly, heated to 95°C under stirring, and reacted for 2 hours to obtain a retarder; the mass concentration of the hydrochloric acid was 35%.

[0034] Example 4

[0035] The difference between this embodiment and embodiment 2 is that 0.36 parts of succinaldehyde is added.

[0036] Example 5

[0037] The difference between this embodiment and embodiment 2 is that 0.54 parts of succinaldehyde are added.

[0038] Example 6

[0039] The difference between this embodiment and embodiment 2 is that 0.18 parts of succinaldehyde is added.

[0040] Example 7

[0041] The difference between this embodiment and embodiment 2 is that 0.72 parts of succinaldehyde is added.

[0042] Example 8

[0043] The difference between this embodiment and embodiment 2 is that 0.18 parts of 4-imidazole acrylic acid is added.

[0044] Example 9

[0045] The difference between this embodiment and embodiment 2 is that 0.54 parts of 4-imidazole acrylic acid is added.

[0046] Example 10

[0047] The difference between this embodiment and embodiment 2 is that 0.09 parts of 4-imidazole acrylic acid is added.

[0048] Embodiment 11

[0049] The difference between this embodiment and embodiment 2 is that 0.72 parts of 4-imidazole acrylic acid is added.

[0050] Comparative Example 1

[0051] The only difference between this comparative example and Example 2 is that 4-imidazole acrylic acid is not added.

[0052] Comparative Example 2

[0053] The only difference between this comparative example and Example 2 is that 4-imidazole acrylic acid is replaced by an equal amount of polyethylene glycol.

[0054] Performance Test:

[0055] The thickening time and compressive strength of the retarders obtained in Examples 1 to 11 and Comparative Examples 1 to 2 were measured at 150° C. according to the method in SY / T 5504.1-2013 “Evaluation Methods for Oil Well Cement Admixtures Part 1: Retarders”. The test results are shown in Table 1.

[0056] Table 1 Test results of the retarder properties obtained in Examples 1 to 11 and Comparative Examples 1 to 2

[0057]

[0058] In the present invention, compared with Example 2, Comparative Example 1 does not add 4-imidazole acrylic acid, and Comparative Example 2 replaces 4-imidazole acrylic acid with an equal amount of polyethylene glycol. As a result, the thickening time and compressive strength in Comparative Examples 1 and 2 are both less than those in Example 2, indicating that adding 4-imidazole acrylic acid to the retarder can improve the retarding property and compressive strength of the retarder at high temperature.

[0059] Compared with Example 2, Examples 8 to 11 changed the amount of 4-imidazole acrylic acid added. As a result, the thickening time and compressive strength in Examples 2 and Examples 8 to 9 were greater than those in Examples 10 to 11, indicating that when the mass of 4-imidazole acrylic acid was 1% to 3% of the sum of the mass of hydroxycarboxylate and polysaccharide, the retarder and the compressive strength at high temperature could be further improved. In addition, the thickening time and the compressive strength in Example 2 were greater than those in Examples 8 to 9, indicating that when the mass of 4-imidazole acrylic acid was 2.1% of the sum of the mass of hydroxycarboxylate and polysaccharide, the retarder and the compressive strength at high temperature could be further improved.

[0060] Compared with Example 2, Examples 4 to 7 changed the amount of succinaldehyde added. As a result, the thickening time and compressive strength in Examples 2 and Examples 4 to 5 were greater than those in Examples 6 to 7, indicating that when the mass of succinaldehyde was 2% to 3% of the sum of the mass of hydroxycarboxylates and polysaccharides, the retarding property and compressive strength of the retarder at high temperature could be further improved. In addition, the thickening time and compressive strength in Example 2 were greater than those in Examples 4 to 5, indicating that when the mass of succinaldehyde was 2.6% of the sum of the mass of hydroxycarboxylates and polysaccharides, the retarding property and compressive strength of the retarder at high temperature could be further improved.

[0061] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high stability retarder for oil well cement, characterized in that: The raw materials include the following components in parts by weight: 3-5 parts of hydroxycarboxylate, 12-15 parts of polysaccharide, 0.05-0.8 parts of 4-imidazole acrylic acid, 2-3 parts of hydrochloric acid, 0.1-0.8 parts of succinaldehyde, and 70-80 parts of deionized water; The mass of the 4-imidazole acrylic acid is 1% to 3% of the total mass of the hydroxycarboxylate and the polysaccharide.

2. A high stability retarder for oil well cement according to claim 1, characterized in that: The mass of the succinaldehyde is 2% to 3% of the total mass of the hydroxycarboxylate and the polysaccharide.

3. A high stability retarder for oil well cement according to claim 1, characterized in that: The mass concentration of the hydrochloric acid is 30% to 35%.

4. A high stability retarder for oil well cement according to claim 1, characterized in that: The hydroxycarboxylate is one or both of sodium gluconate and sodium glucoheptonate dihydrate.

5. A high stability retarder for oil well cement according to claim 1, characterized in that: The polysaccharide is one or more of platycodon polysaccharide, white dextrin and inulin.

6. The method for preparing a high stability retarder for oil well cement according to any one of claims 1 to 5, characterized in that: The following steps are involved: The raw material components are mixed evenly and reacted to obtain a retarder.

7. The method for preparing a high stability retarder for oil well cement according to claim 6, characterized in that: The reaction temperature is 85-95° C., and the reaction time is 2-3 hours.

8. Use of the high stability retarder for oil well cement according to any one of claims 1 to 5 in high temperature oil well cement.

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