A stabilizer for oil well cement and preparation method thereof

Abstract

The present invention relates to the technical field of oil well cement, and proposes a stabilizer for oil well cement, comprising the following raw materials in parts by weight: 40 to 50 parts of fumed silica, 30 to 40 parts of modified attapulgite, 15 to 18 parts of polyacrylamide, and 6 to 8 parts of sepiolite; the modified attapulgite is obtained by modifying attapulgite with N-carboxylmethylamino-2-ethanol and 4-[amino(carboxyl)methyl]-3-methylbenzoic acid. Through the above technical scheme, the problem of oil well cement being prone to sedimentation instability at high temperatures in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil well cement, and in particular to a stabilizer for oil well cement and a preparation method thereof. Background Art

[0002] With the continuous exploitation of oil and gas resources, the focus of oil and gas resource development has been deepened, and deep oil and gas resources have become the key area of ​​exploration and development. However, the formation temperature and pressure of deep wells and ultra-deep wells are high, which will affect the settlement stability of cement slurry. The settlement stability of cement slurry is the premise to ensure that cement slurry has excellent performance. Poor stability directly affects the safety and quality of cementing construction.

[0003] In view of the above problems, existing patents disclose that inorganic mineral stabilizers are added to improve the sedimentation stability of cement slurry at high temperatures. However, adding too much inorganic mineral stabilizer will reduce the compressive strength of cement slurry. Adding high molecular weight organic polymers can solve the problem of reduced compressive strength caused by adding inorganic mineral stabilizers. However, high molecular weight organic polymers are easily degraded and thermally diluted under high temperature conditions, resulting in reduced viscosity of cement slurry and poor ability to suspend solid particles, resulting in high temperature sedimentation instability. Summary of the invention

[0004] The invention provides a stabilizer for oil well cement and a preparation method thereof, which solves the problem in the related art that oil well cement is prone to sedimentation and instability at high temperature.

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

[0006] The present invention provides a stabilizer for oil well cement, comprising the following raw materials in parts by weight: 40 to 50 parts of fumed silica, 30 to 40 parts of modified attapulgite, 15 to 18 parts of polyacrylamide, and 6 to 8 parts of sepiolite;

[0007] The modified attapulgite is obtained by modifying attapulgite with N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid.

[0008] As a further technical solution, the sum of the mass of the N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid is 2% to 4% of the mass of the attapulgite.

[0009] As a further technical solution, the sum of the mass of the N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid is 3% of the mass of attapulgite.

[0010] As a further technical solution, the mass ratio of N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid is 1-4:1.

[0011] As a further technical solution, the mass ratio of N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid is 3:1.

[0012] As a further technical solution, the preparation method of the modified attapulgite includes the following steps: adding attapulgite to an ethanol solution, mixing evenly, adding N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid, adjusting to acidity, modifying, and obtaining modified attapulgite.

[0013] As a further technical solution, the ethanol solution consists of anhydrous ethanol and water in a volume ratio of 2:5.

[0014] As a further technical solution, the modification temperature is 28-35°C, and the modification time is 12-15h.

[0015] As a further technical solution, the particle size of the attapulgite is 20-200 mesh.

[0016] The present invention also includes a method for preparing a stabilizer for oil well cement, comprising the following steps: uniformly mixing the raw material components to obtain the stabilizer for oil well cement.

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

[0018] 1. In the present invention, adding polyacrylamide to the stabilizer for oil well cement can improve the sedimentation stability of cement. However, as the temperature increases, the decomposition of polyacrylamide will be accelerated, resulting in a decrease in cement viscosity, thereby reducing the high-temperature sedimentation stability of cement. In addition, NH3 generated by the decomposition of polyacrylamide will react with calcium and magnesium cations in cement to generate ionic compounds, thereby reducing the compressive strength of cement. Adding attapulgite modified with N-carboxymethylamino-2-ethanol and 4-[amino(carboxyl)methyl]-3-methylbenzoic acid can not only solve the problem of reduced high-temperature sedimentation stability caused by the decomposition of polyacrylamide, but also adsorb NH3 generated by the decomposition of polyacrylamide, avoiding the phenomenon of reduced compressive strength of cement due to the reaction of NH3 with calcium and magnesium cations in cement, thereby ensuring that cement still has high sedimentation stability and compressive strength at high temperatures. 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 of fumed silica is TS-610;

[0022] The particle size of attapulgite is 20~200 mesh;

[0023] The model of polyacrylamide is YX-SC50, and the particle size is 60 mesh;

[0024] The density of sepiolite is 1~2.3g / cm 3 , the manufacturer is Hebei Jiegui Mineral Products Co., Ltd.;

[0025] The ethanol solution consists of anhydrous ethanol and water in a volume ratio of 2:5.

[0026] Example 1

[0027] A method for preparing a stabilizer for oil well cement comprises the following steps:

[0028] 40 parts of fumed silica, 30 parts of modified attapulgite, 15 parts of polyacrylamide and 6 parts of sepiolite are dry-mixed and mixed evenly to obtain a stabilizer for oil well cement.

[0029] The preparation method of modified attapulgite comprises the following steps:

[0030] Add 50 g of 20-mesh attapulgite to 300 mL of ethanol solution and mix well. Add 0.75 g of N-carboxymethylamino-2-ethanol and 0.75 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid. Adjust the pH to 3 with 2 mol / L hydrochloric acid solution. Modify at 28°C for 15 h, centrifuge, wash, dry, and pass through a 200-mesh sieve to obtain modified attapulgite.

[0031] Example 2

[0032] A method for preparing a stabilizer for oil well cement comprises the following steps:

[0033] 45 parts of fumed silica, 35 parts of modified attapulgite, 17 parts of polyacrylamide and 7 parts of sepiolite are dry-mixed and mixed evenly to obtain a stabilizer for oil well cement.

[0034] The preparation method of modified attapulgite comprises the following steps:

[0035] Add 50 g of 150 mesh attapulgite to 300 mL of ethanol solution and mix well. Add 0.75 g of N-carboxymethylamino-2-ethanol and 0.75 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid. Adjust the pH to 3 with 2 mol / L hydrochloric acid solution. Modify at 30°C for 13 h, centrifuge, wash, dry, and pass through a 200 mesh sieve to obtain modified attapulgite.

[0036] Example 3

[0037] A method for preparing a stabilizer for oil well cement comprises the following steps:

[0038] 50 parts of fumed silica, 40 parts of modified attapulgite, 18 parts of polyacrylamide and 8 parts of sepiolite are dry-mixed and mixed evenly to obtain a stabilizer for oil well cement.

[0039] The preparation method of modified attapulgite comprises the following steps:

[0040] Add 50 g of 200-mesh attapulgite to 300 mL of ethanol solution and mix well. Add 0.75 g of N-carboxymethylamino-2-ethanol and 0.75 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid. Adjust the pH to 4 with 2 mol / L hydrochloric acid solution. Modify at 35 ° C for 12 h, centrifuge, wash, dry, and pass through a 200-mesh sieve to obtain modified attapulgite.

[0041] Example 4

[0042] The difference between this embodiment and embodiment 1 is that 0.5 g of N-carboxymethylamino-2-ethanol and 0.5 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid are added.

[0043] Example 5

[0044] The difference between this embodiment and embodiment 1 is that 1 g of N-carboxymethylamino-2-ethanol and 1 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid are added.

[0045] Example 6

[0046] The difference between this embodiment and embodiment 1 is that 0.25 g of N-carboxymethylamino-2-ethanol and 0.25 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid are added.

[0047] Example 7

[0048] The difference between this embodiment and embodiment 1 is that 1.25 g of N-carboxymethylamino-2-ethanol and 1.25 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid are added.

[0049] Example 8

[0050] The difference between this embodiment and embodiment 1 is that 1.125 g of N-carboxymethylamino-2-ethanol and 0.375 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid are added.

[0051] Example 9

[0052] The difference between this embodiment and embodiment 1 is that 1.2 g of N-carboxymethylamino-2-ethanol and 0.3 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid are added.

[0053] Example 10

[0054] The difference between this embodiment and embodiment 1 is that 0.5 g of N-carboxymethylamino-2-ethanol and 1.0 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid are added.

[0055] Embodiment 11

[0056] The difference between this embodiment and embodiment 1 is that 1.25 g of N-carboxymethylamino-2-ethanol and 0.25 g of 4-[amino(carboxy)methyl]-3-methylbenzoic acid are added.

[0057] Comparative Example 1

[0058] The only difference between this comparative example and Example 1 is that no modified attapulgite is added.

[0059] Comparative Example 2

[0060] The only difference between this comparative example and Example 1 is that the modified attapulgite is replaced by an equal amount of attapulgite.

[0061] Comparative Example 3

[0062] The only difference between this comparative example and Example 1 is that N-carboxymethylamino-2-ethanol is not added.

[0063] Comparative Example 4

[0064] This comparative example is compared with Example 1, the only difference being that 4-[amino(carboxyl)methyl]-3-methylbenzoic acid is not added.

[0065] Performance Test:

[0066] The stabilizers for oil well cement obtained in Examples 1 to 11 and Comparative Examples 1 to 4 are added to cement slurry and proportioned according to the following formula: G-grade oil well cement (based on 100 wt% of G-grade oil well cement) + 35 wt% quartz sand + 0.5 wt% stabilizer + 2 wt% high temperature retarder + 6 wt% high temperature fluid loss reducer, wherein the stabilizers are respectively selected from the stabilizers for oil well cement obtained in Examples 1 to 11 and Comparative Examples 1 to 4, the high temperature retarder is sodium gluconate, the high temperature fluid loss reducer is AMPS polymer, the G-grade oil well cement is provided by Camabella (Beijing) Technology Co., Ltd., and the quartz sand particle size is 325 mesh; the test temperature is 150°C; then according to the determination method in GB / T19139-2012 "Test Methods for Oil Well Cement", the compressive strength and sedimentation stability are determined, and the performance test results are shown in Table 1.

[0067] Table 1 Performance test results of stabilizers for oil well cement obtained from Examples 1 to 11 and Comparative Examples 1 to 4

[0068]

[0069] In the present invention, compared with Example 1, Comparative Example 1 does not add modified attapulgite, Comparative Example 2 replaces the modified attapulgite with an equal amount of attapulgite, Comparative Example 3 does not add N-carboxymethylamino-2-ethanol, and Comparative Example 4 does not add 4-[amino(carboxy)methyl]-3-methylbenzoic acid. As a result, the compressive strength and sedimentation stability of Comparative Examples 1 to 4 are both lower than those of Example 1, indicating that adding attapulgite modified with N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid to the stabilizer for oil well cement can improve the compressive strength and sedimentation stability of oil well cement.

[0070] Compared with Example 1, Examples 4 to 7 changed the mass of N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid and the proportion of the mass of attapulgite. As a result, the compressive strength and sedimentation stability in Examples 6 to 7 were less than those in Examples 1 and 4 to 5, indicating that when the sum of the mass of N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid was 2% to 4% of the mass of attapulgite, the compressive strength and sedimentation stability of oil well cement could be further improved, and the compressive strength and sedimentation stability in Example 1 were greater than those in Examples 4 to 5, indicating that when the sum of the mass of N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid was 3% of the mass of attapulgite, the compressive strength and sedimentation stability of oil well cement could be further improved.

[0071] Compared with Example 1, Examples 8 to 11 changed the mass ratio of N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid. As a result, the compressive strength and sedimentation stability in Examples 10 to 11 were less than those in Examples 1 and 8 to 9, indicating that when the mass ratio of N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid was 1 to 4:1, the compressive strength and sedimentation stability of oil well cement could be further improved, and the compressive strength and sedimentation stability in Example 8 were greater than those in Example 1 and 9, indicating that when the mass ratio of N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid was 3:1, the compressive strength and sedimentation stability of oil well cement could be further improved.

[0072] 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 stabilizer for oil well cement, characterized in that: The raw materials include the following components in parts by weight: 40-50 parts of fumed silica, 30-40 parts of modified attapulgite, 15-18 parts of polyacrylamide, and 6-8 parts of sepiolite; The modified attapulgite is obtained by modifying attapulgite with N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid; The preparation method of the modified attapulgite comprises the following steps: adding attapulgite to an ethanol solution, mixing evenly, adding N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid, adjusting to acidity, performing modification, and obtaining modified attapulgite; The modification temperature is 28-35° C., and the modification time is 12-15 hours.

2. A stabilizer for oil well cement according to claim 1, characterized in that: The sum of the mass of the N-carboxymethylamino-2-ethanol and 4-[amino(carboxy)methyl]-3-methylbenzoic acid is 2% to 4% of the mass of the attapulgite.

3. A stabilizer for oil well cement according to claim 1, characterized in that: The mass ratio of the N-carboxymethylamino-2-ethanol to 4-[amino(carboxy)methyl]-3-methylbenzoic acid is 1-4:

1.

4. A stabilizer for oil well cement according to claim 1, characterized in that: The particle size of the attapulgite is 20-200 meshes.

5. The method for preparing a stabilizer for oil well cement according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: mixing the raw material components uniformly to obtain a stabilizer for oil well cement.

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