A high-temperature clay stabilizer containing rigid groups and its preparation method

Abstract

This invention provides a high-temperature resistant clay stabilizer containing rigid groups and its preparation method. Its structure contains rigid benzene rings, polyether segments, polyamide groups, and ammonium ions, exhibiting advantages such as good temperature resistance, excellent anti-swelling effect, strong adsorption, and good water washability. The high-temperature resistant clay stabilizer with rigid groups provided by this invention achieves an anti-swelling rate of over 90%, a shrinkage-swelling rate of over 50%, a temperature resistance of up to 300℃, a water washability of 100%, and a core permeability retention value of over 90%. It can be used for water injection anti-swelling, acid fracturing anti-swelling, and heavy oil thermal recovery anti-swelling in oilfields.

Description

Technical Field

[0001] This invention relates to a high-temperature resistant clay stabilizer and its preparation method, belonging to the field of petroleum engineering technology. Background Technology

[0002] Clay minerals are widely present in oil reservoirs, with 97% of the world's oil reservoirs containing clay minerals to varying degrees. Generally, an oil reservoir containing 5%–20% clay is considered to have a high clay content. During oilfield development (water injection, acidizing, fracturing), if improper measures are taken, these clays will expand, disperse, and migrate when they encounter external water or water-based substances. During expansion, the clay absorbs water into its crystal structure, leading to an increase in clay volume and thus clogging formation pores. During migration, clay material is dispersed by external liquids or carried by produced fluids, forming bridging or throttling points at the pore throats of capillaries, blocking pore channels and reducing formation permeability. This is particularly detrimental to low-permeability reservoirs. Therefore, for reservoirs with high clay content and high water sensitivity, water-based working fluid intrusion can cause water-sensitive damage in any process such as drilling, cementing, water injection, fracturing, acidizing, well workover, and well kill. The most common way to solve water-sensitive damage is to add clay stabilizers to the injected water. Therefore, the development and use of high-quality and efficient anti-swelling agents are important measures to ensure stable oilfield production.

[0003] As oil resource exploration deepens, reservoir depths increase, and reservoir temperatures rise, demanding higher temperature resistance from chemical treatment agents used in oil and gas well operations. Currently, commonly used clay stabilizers are predominantly applied to protect formation permeability in shallow areas, with temperature resistance generally below 200℃. Analysis suggests two main possibilities for insufficient temperature resistance: first, the agent itself may lack thermal stability, decomposing at high temperatures and failing to prevent swelling; second, the agent's adsorption to clay may weaken at high temperatures, preventing effective adsorption within the clay and thus reducing its effectiveness. Summary of the Invention

[0004] This invention provides a high-temperature resistant clay stabilizer containing rigid groups and its preparation method. First, by introducing a benzene ring into the main molecular chain structure of the clay stabilizer, the chemical bonding strength of the polymer main chain is increased due to the ring structure and π-bond characteristics of the benzene ring (carbon-carbon double bond strength > carbon-carbon single bond strength), which further improves the thermal stability of the clay stabilizer itself. Second, this high-temperature resistant clay stabilizer containing rigid groups has multiple amide groups and ammonium ions in its molecular structure, resulting in strong adsorption to the formation, allowing it to maintain its thermal stability even under high-temperature conditions. First, it adsorbs inside the clay, thus preventing swelling. Second, its molecular main chain structure contains polyether chains and benzene ring structures. When it is adsorbed inside the clay, the hydrophobicity of the polyether chains and benzene ring structures can not only drive away water molecules that have entered the clay layers, but also prevent external water molecules from re-entering the clay, which is beneficial to improving the anti-swelling performance. Third, because its structure contains multiple amide groups and ammonium ions, it can adsorb on the already hydrated and dispersed clay layers, which can pull the already hydrated and dispersed layers closer and tighter, thus having a shrinkage and swelling effect.

[0005] The present invention achieves the above objectives through the following technical solutions.

[0006] This invention provides a high-temperature resistant clay stabilizer containing rigid groups, characterized by the following structure: the main chain of the high-temperature resistant clay stabilizer molecule contains polyether segments, rigid benzene ring groups, amide groups and ammonium ions that can be strongly adsorbed in the formation, and its general structural formula is one of the following three:

[0007] Where R1 and R2 are hydrogen or methyl; R3 is hydrogen, methyl, ethyl, propyl, phenyl or benzyl; and n is 2-8.

[0008] This invention also provides a method for preparing a high-temperature clay stabilizer containing rigid groups, characterized by the following preparation steps:

[0009] (1) A diacid containing a rigid group and a diamine containing a polyether segment are reacted to generate an intermediate product with the following general structural formula:

[0010] Wherein, R1 and R2 are hydrogen or methyl; n is 2-8;

[0011] (2) Add organic acid to the intermediate product generated in step (1) and adjust the pH value to obtain a high-temperature clay stabilizer containing rigid groups.

[0012] The dicarboxylic acid containing a rigid group is phthalic acid, isophthalic acid, or terephthalic acid.

[0013] The general formula of the diamine containing polyether segments is:

[0014] Where R1 and R2 are hydrogen or methyl; n is 2-8.

[0015] The organic acid mentioned is formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, or phenylacetic acid.

[0016] The molar ratio of the diacid containing rigid groups to the diamine containing polyether segments is 1:2.05-1:5.

[0017] The reaction step (1) is as follows: add the diamine containing polyether segments into the reactor, start stirring, and purge nitrogen gas throughout for protection, then start heating, and keep the temperature constant when it reaches 160°C; dissolve the diacid containing rigid groups with a dispersant, and then start adding the dispersant solution containing the diacid containing rigid groups dropwise. After the addition is complete, continue heating to 180°C, keep this temperature until no more water is removed, continue the reaction for 30 min, then stop the reaction and cool down.

[0018] The dispersant is methanol, ethanol, or acetone.

[0019] In reaction step (2), the pH value is adjusted to 7-9.

[0020] The aforementioned high-temperature clay stabilizer containing rigid groups can be used for water injection anti-swelling, acid fracturing anti-swelling, and heavy oil thermal recovery anti-swelling in oil fields.

[0021] The temperature-resistant clay stabilizer provided by this invention enhances thermal stability through the introduction of rigid benzene ring groups, resulting in a significant temperature resistance effect, reaching up to 300℃. Utilizing the hydrophobic properties of the benzene ring and polyether chain, it effectively inhibits the hydration and swelling of clay, exhibiting good anti-swelling and shrinkage-swelling properties, with an anti-swelling rate exceeding 90% and a shrinkage-swelling rate exceeding 50%. Furthermore, the presence of multiple amide groups and ammonium ions in the structure enhances adsorption performance at high temperatures, achieving a 100% water wash resistance rate and a core permeability retention value exceeding 90%. Implementation

[0022] The present invention will now be described in detail with reference to embodiments and comparative examples. Example

[0023] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0024]

[0025] R1 and R2 are both methyl groups; n is 3.

[0026] Weigh 0.3 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0027] Weigh 0.1 mol of terephthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing terephthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0028] Reaction step (2): Add 0.4 mol of formic acid to the reaction product obtained in step (1) and control the pH value to 7. Example

[0029] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0030]

[0031] R1 and R2 are both methyl groups; n is 5.

[0032] Weigh 0.205 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0033] Weigh 0.1 mol of isophthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing isophthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0034] Reaction step (2): Add 0.21 mol of benzoic acid to the reaction product obtained in step (1) and control the pH value to 7. Example

[0035] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0036]

[0037] R1 and R2 are both methyl groups; n is 8.

[0038] Weigh 0.5 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0039] Weigh 0.1 mol of phthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing phthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0040] Reaction step (2): Add 0.8 mol of acetic acid to the reaction product obtained in step (1) and control the pH value to 7. Example

[0041] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0042]

[0043] R1 and R2 are both methyl groups; n is 5.

[0044] Weigh 0.205 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0045] Weigh 0.1 mol of terephthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing terephthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0046] Reaction step (2): Add 0.205 mol of benzoic acid to the reaction product obtained in step (1) and control the pH value to 9.

[0047] Example 5

[0048] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0049]

[0050] R1 and R2 are both methyl groups; n is 5.

[0051] Weigh 0.205 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0052] Weigh 0.1 mol of isophthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing isophthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0053] Reaction step (2): Add 0.208 mol of benzoic acid to the reaction product obtained in step (1) and control the pH value to 8.

[0054] Example 6

[0055] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0056]

[0057] Where R1 is methyl, R2 is hydrogen, and n is 3.

[0058] Weigh 0.3 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0059] Weigh 0.1 mol of phthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing phthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0060] Reaction step (2): Add 0.4 mol of formic acid to the reaction product obtained in step (1) and control the pH value to 7.

[0061] Example 7

[0062] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0063]

[0064] Where R1 is hydrogen, R2 is methyl, and n is 3.

[0065] Weigh 0.3 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0066] Weigh 0.1 mol of terephthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing terephthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0067] Reaction step (2): Add 0.4 mol of formic acid to the reaction product obtained in step (1) and control the pH value to 7.

[0068] Example 8

[0069] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0070]

[0071] Where R1 is methyl, R2 is hydrogen, and n is 2.

[0072] Weigh 0.25 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0073] Weigh 0.1 mol of isophthalic acid and dissolve it in ethanol. Then transfer the solution to a dropping funnel and start adding the ethanol solution containing isophthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0074] Reaction step (2): Add 0.3 mol of butyric acid to the reaction product obtained in step (1) and control the pH value to 7.

[0075] Example 9

[0076] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0077]

[0078] R1 and R2 are both hydrogen; n is 7.

[0079] Weigh 0.4 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0080] Weigh 0.1 mol of phthalic acid and dissolve it in acetone. Then transfer the solution to a dropping funnel and start adding the acetone solution containing phthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 minutes, stop the reaction, and cool down.

[0081] Reaction step (2): Add 0.6 mol of phenylacetic acid to the reaction product obtained in step (1) and control the pH value to 7.

[0082] Comparative Example 1

[0083] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0084]

[0085] R1 and R2 are both methyl groups; n is 5.

[0086] Weigh 0.15 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0087] Weigh 0.1 mol of isophthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing isophthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0088] Reaction step (2): Add 0.1 mol of benzoic acid to the reaction product obtained in step (1) and control the pH value to 7.

[0089] Comparative Example 2

[0090] In Example 2, isophthalic acid was not introduced. 0.15 mol of a diamine containing polyether segments was weighed and added to a flask, followed by 0.3 mol of benzoic acid, and the pH was controlled to 7.

[0091] Comparative Example 3

[0092] Reaction step (1): Weigh 0.5 mol of 1,2-propanediamine into a flask, start stirring, and purge with nitrogen gas throughout the process for protection, and then start heating; keep the temperature constant when it reaches 160℃.

[0093] Weigh 0.1 mol of phthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing phthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0094] Reaction step (2): Add 0.8 mol of acetic acid to the reaction product obtained in step (1) and control the pH value to 7.

[0095] Comparative Example 4

[0096] Reaction step (1): The structure of the diamine containing polyether segments is selected as follows:

[0097]

[0098] R1 and R2 are both methyl groups; n is 5.

[0099] Weigh 0.205 mol of a diamine containing polyether segments and add it to a flask. Start stirring and purge with nitrogen gas throughout the process for protection. Then start heating. Keep the temperature constant when it reaches 160°C.

[0100] Weigh 0.1 mol of isophthalic acid and dissolve it in methanol. Then transfer the solution to a dropping funnel and start adding the methanol solution containing isophthalic acid dropwise to the flask. After the addition is complete, continue heating to 180°C and react until no more water is removed. Then react for another 30 min, stop the reaction, and cool down.

[0101] The reaction step (2) of adjusting the pH value is no longer performed, and the product obtained in reaction step (1) is directly used as a clay stabilizer sample.

[0102] Test Example 1

[0103] The anti-swelling rate test was conducted according to the "Sy / T5971-2016 Performance Evaluation Method of Clay Stabilizer for Water Injection". The steps are as follows: Weigh 0.5 g of sodium bentonite, add it to a 10 mL centrifuge tube, add deionized water to the 10 mL mark, shake thoroughly, let stand at room temperature for 2 h, put it into a centrifuge, and centrifuge at 1500 r / min for 15 min. Read the volume V2 of sodium bentonite in water. Use the same steps but replace water with a clay stabilizer aqueous solution of a certain concentration to measure the volume V1 of the soil after centrifugation. Use kerosene instead of water to measure the volume V0 of the soil.

[0104]

[0105] Where: η—anti-swelling rate, %; V0—volume of sodium bentonite in kerosene, mL; V1—volume of sodium bentonite in clay stabilizer, mL; V2—volume of sodium bentonite in water, mL.

[0106] Test Example 2

[0107] The steps for testing the anti-swelling rate after aging at 300℃ are as follows:

[0108] (1) Weigh 3.00 g of bentonite powder, accurate to 0.01 g, and put it into a high-temperature and high-pressure closed reactor;

[0109] (2) Add 60 mL of 4% clay stabilizer solution, shake well and mix thoroughly, then place in an oven at 300±2℃ for 24 h and cool to room temperature;

[0110] (3) Transfer all the clay mixture in the high-temperature, high-pressure closed reactor into a 100 mL beaker, shake thoroughly, quickly remove 10 mL and add it to a glass centrifuge tube, place it in a centrifuge with an automatic balancing function, centrifuge at 1500 r / min for 15 min, and read the swelling volume V1 of the bentonite. The formula for calculating the anti-swelling rate is as follows:

[0111]

[0112] In the formula: V0 is the expansion volume of bentonite in kerosene; V1 is the expansion volume of bentonite in an aqueous solution of clay stabilizer; V2 is the expansion volume of bentonite in water.

[0113] Experimental Example 3

[0114] The test procedure for water wash resistance is as follows:

[0115] Pour out the supernatant from the centrifuge tube in Experiment Example 2 above, add deionized water to 10 mL, stir thoroughly, let stand for 2 h, and then centrifuge at 1500 r / min for 15 min. Finally, read the final volume V1 of bentonite in the centrifuge tube. ′ .

[0116] Formula for calculating water wash resistance:

[0117]

[0118] In the formula: V1 is the swelling volume of bentonite in the clay stabilizer aqueous solution, mL;

[0119] V1 ′ V1 represents the volume of bentonite that has expanded after being washed with water, in mL; V2 represents the volume of bentonite that has expanded in water, in mL.

[0120] Test Example 4

[0121] The shrinkage-expansion ratio test procedure is as follows:

[0122] Weigh 0.5 g of sodium bentonite and add it to a 10 mL centrifuge tube. Add deionized water to the 10 mL mark, shake well, and let stand at room temperature for 2 h. Then, place the tube in a centrifuge and centrifuge at 1500 r / min for 15 min. Read the volume V2 of the sodium bentonite in water. Pour out the water, add a clay stabilizer solution of a certain concentration to the expanded bentonite instead of water, and measure the volume V1 of the soil after centrifugation. Measure the volume V0 of the soil using kerosene instead of water.

[0123]

[0124] In the formula: η—anti-swelling rate, %; V0—volume of sodium bentonite in kerosene, mL; V1—volume of expanded sodium bentonite in clay stabilizer, mL; V2—volume of sodium bentonite in water, mL.

[0125] Experimental Example 5

[0126] The original core permeability K0 was tested using a core displacement test. Then, the core was saturated with simulated formation water. A clay stabilizer solution system was then injected into the core tube at 300°C, followed by high-temperature steam at 300°C. Finally, the permeability K1 of the core after the experiment was tested. K1 / K0 is the core permeability retention value.

[0127] Table 1 Sample Evaluation Results

[0128] Room temperature anti-expansion rate, % Anti-swelling rate after aging at 300℃, % Swelling rate, % Washing resistance, % Core permeability retention value, % Remark Example 1 93.9 91.5 51.6 100 91.6 Example 2 94.3 92.2 52.4 100 92.0 Example 3 95.7 92.8 53.9 100 93.5 Example 4 91.7 90.8 50.6 100 90.8 Example 5 92.5 91.2 51.0 100 91.2 Example 6 93.7 91.5 51.5 100 91.8 Example 7 90.7 90.3 50.1 100 90.3 Example 8 93.6 92.0 52.1 100 91.7 Example 9 94.5 92.4 52.7 100 92.5 Comparative Example 1 — — — — — Not water-soluble, cannot be tested Comparative Example 2 92.1 78.2 51.6 100 76.1 Comparative Example 3 84.1 82.8 44.9 100 78.5 Comparative Example 4 86.5 85.3 45.7 98.7 86.1 blank 12.3

Claims

1. A high-temperature clay stabilizer containing rigid groups, characterized in that... The structure is as follows: The main chain of this high-temperature clay stabilizer contains polyether segments, rigid benzene ring groups, amide groups and ammonium ions that can be strongly adsorbed in the formation. Its general structural formula is one of the following three: Where R1 and R2 are hydrogen or methyl; R3 is hydrogen, methyl, ethyl, propyl, phenyl or benzyl; and n is 2-8.

2. A method for preparing a high-temperature clay stabilizer containing rigid groups, characterized in that... The preparation steps are as follows: (1) A diacid containing a rigid group and a diamine containing a polyether segment are reacted to generate an intermediate product with the following general structural formula: Wherein, R1 and R2 are hydrogen or methyl; n is 2-8; (2) Add organic acid to the intermediate product generated in step (1) and adjust the pH value to obtain a high-temperature clay stabilizer containing rigid groups.

3. The method for preparing a high-temperature clay stabilizer containing rigid groups as described in claim 2, characterized in that: The dicarboxylic acid containing a rigid group is phthalic acid, isophthalic acid, or terephthalic acid.

4. The method for preparing a high-temperature clay stabilizer containing rigid groups as described in claim 2, characterized in that: The general formula of the diamine containing polyether segments is: Where R1 and R2 are hydrogen or methyl; n is 2-8.

5. The method for preparing a high-temperature clay stabilizer containing rigid groups as described in claim 2, characterized in that: The organic acid mentioned is formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, or phenylacetic acid.

6. The method for preparing a high-temperature clay stabilizer containing rigid groups as described in claim 2, characterized in that: The molar ratio of a diacid containing a rigid group to a diamine containing a polyether segment is 1:2.05-1:

5.

7. The method for preparing a high-temperature clay stabilizer containing rigid groups as described in claim 2, characterized in that: The reaction step (1) is as follows: add the diamine containing polyether segments into the reactor, start stirring, and purge nitrogen gas throughout the process for protection, then start heating, and keep the temperature constant when it reaches 160℃; dissolve the diacid containing rigid groups with a dispersant, and then start adding the dispersant solution containing the diacid containing rigid groups dropwise. After the addition is complete, continue heating to 180℃, keep this temperature until no more water is removed, continue the reaction for 30 min, then stop the reaction and cool down.

8. The method for preparing a high-temperature clay stabilizer containing rigid groups as described in claim 7, characterized in that: The dispersant is methanol, ethanol, or acetone.

9. The method for preparing a high-temperature clay stabilizer containing rigid groups as described in claim 2, characterized in that: In reaction step (2), the pH value is adjusted to 7-9.

10. A high-temperature clay stabilizer containing rigid groups as described in claim 1, characterized in that... The aforementioned high-temperature clay stabilizer containing rigid groups is used for preventing swelling during water injection, acid fracturing, and heavy oil thermal recovery in oil fields.

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