High-temperature-resistant waterproof lock fracturing fluid as well as preparation method and application thereof
By developing fracturing fluid formulations containing oleamide and erucamide surfactants, the problems of insufficient temperature resistance and water-locking effect in deep tight gas reservoirs were solved, enabling effective fracturing operations and increased production under high-temperature conditions.
Patent Information
- Application Number
- CN202411061711.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-05
- Publication Date
- 2026-02-06
AI Technical Summary
Existing fracturing fluids are not sufficiently temperature-resistant in deep tight gas reservoirs and are prone to water-locking effects, leading to permeability damage and reduced gas well production.
A fracturing fluid formulation composed of oleamide and erucamide surfactants, sodium salicylate, water-locking inhibitors, synergists, and pH adjusters is prepared through a specific process to enhance temperature resistance and inhibit water-locking.
In deep tight gas reservoirs with well temperatures not exceeding 200℃, it significantly reduces water lock damage, increases gas well production, and ensures construction effectiveness.
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Figure CN121471898A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of fracturing fluid for oil exploitation, in particular to a high-temperature-resistant and water-lock-preventing fracturing fluid suitable for deep tight gas reservoirs. BACKGROUND
[0002] According to the overall planning and deployment of oilfield companies in the field of natural gas, deep gas in Liaohe Basin will be an important field for exploration in the next five years. Among them, deep volcanic rock and clastic rock are the key targets for exploration. Such reservoirs are ultra-deep (> 4500m), high temperature (> 180℃), high pressure (> 1.2) gas reservoirs, with diverse and complex lithology, low porosity and low permeability, which need to be fractured to obtain industrial gas flow, so as to realize the upgrading of reserves. In large-scale fracturing of deep tight gas reservoirs, the performance of fracturing fluid is one of the key factors determining the success of the operation. Therefore, it is necessary to strengthen the research on fracturing fluid for deep gas wells and improve the efficiency of fracturing engineering technical measures.
[0003] For deep tight gas reservoirs, deep burial and high temperature are one of their main characteristics, which requires the fracturing fluid to have good temperature and shear resistance. In addition, water lock effect is another problem that cannot be ignored in tight gas reservoirs. Once water lock occurs, the permeability damage rate increases rapidly, which greatly reduces the gas well production. Therefore, the fracturing fluid suitable for deep tight gas wells needs to meet the quality requirements of high temperature resistance and water lock prevention at the same time. SUMMARY
[0004] To solve the above technical problems, the present application provides a fracturing fluid, which comprises, based on the total mass of the fracturing fluid being 100%, 1-3% of oleic acid amide surfactant, 1-3% of erucic acid amide surfactant, 0.5-2.5% of sodium salicylate, 0.2-0.8% of water lock inhibitor, 0.3-0.6% of synergist, 0.01-0.04% of pH regulator, 0.5-1% of clay stabilizer, and 89-96% of water.
[0005] The oleic acid amide / erucic acid amide surfactant is an oleic acid / erucic acid amide propylene glycol surfactant prepared by reacting oleic acid amide / erucic acid amide with 3-chloropropylene glycol, which has better viscoelasticity than oleic acid amide / erucic acid amide betaine and is more suitable for use as a fracturing fluid thickening agent. The specific preparation method is as follows: (1) industrial oleic acid amide / erucic acid amide, 3-chloropropylene glycol and propylene oxide are placed in a three-necked flask with a condenser at a mass ratio of 1:1:2, heated to 95℃ in water bath, and stirred for 20-24h under reflux; (2) the product after reaction is subjected to reduced pressure distillation to remove the solvent; (3) a small amount of dichloromethane is added for dissolution, and after dissolution, it is slowly dropped into excess ethyl acetate for recrystallization purification; (4) the supernatant is removed, and the solvent is removed by reduced pressure distillation to obtain the solid oleic acid amide / erucic acid amide surfactant;
[0006] In the above preparation method, the water-locking inhibitor is a mixture of methanol and a fluorinated surfactant, with a mass ratio of 1:0.1-0.3. Specifically, the fluorinated surfactant is a fluorinated surfactant with a perfluoropolyether structure. Preferably, the structural formula of the perfluoropolyether fluorinated surfactant can be selected from one of CF3CF2CF2OCF(CF3)CF2OCF(CF3)COONH4, CF3CF2OCF(CF3)CF2OCF(CF3)COONH4, and CF3OCF2OCF2OCF2OCF2COONH4.
[0007] In the above preparation method, preferably, the synergist is selected from one of octadecyl 4-methylbenzenesulfonate or octadecyl 4-chlorobenzenesulfonate;
[0008] In the above preparation method, preferably, the pH adjuster is selected from potassium hydroxide or sodium bicarbonate;
[0009] In the above preparation method, preferably, the clay stabilizer is selected from potassium chloride or ammonium chloride.
[0010] The present invention also provides a method for preparing the above-mentioned fracturing fluid, comprising:
[0011] S1: Dissolve a mixture of oleamide surfactants and erucamide surfactants in warm water to obtain solution A; dissolve a water-locking inhibitor and a clay stabilizer in water to obtain solution B;
[0012] S2: Add solution B from S1 to solution A, stir, and obtain mixed solution C;
[0013] S3: Add pH adjuster and synergist to the mixed solution C of S2, stir, then add sodium salicylate aqueous solution, and continue stirring to obtain the fracturing fluid.
[0014] In the above preparation method, preferably, in S1, the temperature of the warm water is 50-70℃.
[0015] In the above preparation method, preferably, in S2, the rate at which solution B is added to solution A is 2-5 mL / s.
[0016] In the above preparation method, preferably, in step S3, the rate at which the sodium salicylate aqueous solution is added is 2-5 mL / s.
[0017] This invention also provides the application of the above-mentioned fracturing fluid in fracturing deep tight gas wells with well temperatures not exceeding 200°C. When applying the above-mentioned fracturing fluid to fracturing operations in deep tight gas reservoirs, the operation can be carried out in a conventional manner.
[0018] The advantages of this invention over the prior art are as follows:
[0019] (1) When the fracturing fluid provided by the present invention is applied to the fracturing of deep tight gas reservoirs, it can more effectively suppress the occurrence of water lock phenomenon, reduce water lock damage to the reservoir, and increase gas well production while ensuring the needs of on-site construction.
[0020] (2) The fracturing fluid provided by the present invention has stronger temperature resistance and can be applied to reservoirs with well temperatures up to 200°C. Attached Figure Description
[0021] Figure 1 For fracturing fluid A at 200℃ for 170 seconds -1 The temperature resistance and shear resistance curves are shown below.
[0022] Figure 2 For fracturing fluid B at 200℃ for 170 seconds -1 The temperature resistance and shear resistance curves are shown below.
[0023] Figure 3 For fracturing fluid C at 200℃ for 170s -1 The temperature resistance and shear resistance curves are shown below. Detailed Implementation
[0024] Example 1:
[0025] This embodiment provides a high-temperature resistant, waterproof, low-damage fracturing fluid A, the preparation method of which includes the following steps:
[0026] 1. Preparation of oleamide surfactants
[0027] 30g of oleamide, 30g of 3-chloropropanediol, and 60g of propylene oxide were placed in a three-necked flask equipped with a condenser and heated to 95°C in a water bath. The mixture was stirred and refluxed for 24 hours. The propylene oxide was removed from the product by vacuum distillation. A small amount of dichloromethane was added to dissolve the product. After dissolution, the product was slowly added dropwise to excess ethyl acetate for recrystallization purification. The supernatant was removed, and the solvent was removed by vacuum distillation to obtain a solid oleamide surfactant.
[0028] 2. Preparation of erucamide surfactants
[0029] The synthesis method of erucamide surfactants is the same as that of oleamide surfactants, except that oleamide is replaced with erucamide.
[0030] 3. Preparation of water-locking inhibitors
[0031] 10g of methanol and 1.3g of a fluorinated surfactant with a perfluoropolyether structure (structural formula CF3CF2CF2OCF(CF3)CF2OCF(CF3)COONH4) were mixed evenly at 60°C to obtain water-locking inhibitor A.
[0032] 4. Preparation of fracturing fluid
[0033] Dissolve 4g each of the prepared oleamide surfactant and the prepared erucamide surfactant in 150mL of warm water at 60℃ and stir until homogeneous to obtain a surfactant solution. Dissolve 1.2g of the prepared water-locking inhibitor A and 1g of potassium chloride in 40mL of water and slowly pour this solution into the surfactant solution at a rate of 3mL / s, stirring until homogeneous. Continue to add 0.05g of potassium hydroxide and 1g of octadecyl 4-methylbenzenesulfonate to the mixed solution and stir until homogeneous to obtain a mixed solution. Then, dissolve 4g of sodium salicylate in 10mL of water and slowly add this sodium salicylate solution into the aforementioned mixed solution at a rate of 3mL / s, stirring until homogeneous to obtain the fracturing fluid A.
[0034] The temperature resistance and shear strength of the fracturing fluid A prepared in this embodiment were tested. Figure 1 For this fracturing fluid at 200℃ for 170 seconds -1 The temperature resistance and shear strength characteristic curves are shown below. From... Figure 1 It can be seen that the viscosity of the fracturing fluid prepared in this embodiment is still above 50 mPa·s at 200℃, indicating that the fracturing fluid has a temperature resistance of 200℃, which can meet the fracturing construction requirements of reservoirs with temperatures not higher than 200℃.
[0035] It is generally believed that reducing the surface tension of the influent fluid, decreasing capillary resistance, increasing displacement capacity, or expelling intruding fluid helps improve effective gas permeability and mitigate water-locking effects. Therefore, the magnitude of surface tension can be used to evaluate water-locking damage. Using a surface tension meter, the surface tension of the ruptured fluid of fracturing fluid A prepared in this embodiment was measured by the dip plate method at a test temperature of 20°C. The result was 21.3 Nm / m, a relatively low value, indicating that it can significantly reduce water-locking damage caused by fracturing fluid.
[0036] Example 2:
[0037] This embodiment provides a high-temperature resistant, waterproof, low-damage fracturing fluid B, the preparation method of which includes the following steps:
[0038] 1. Preparation of oleamide / erucamide surfactants
[0039] The preparation methods for oleamide surfactants and erucamide surfactants are the same as in Example 1.
[0040] 2. Preparation of water-locking inhibitors
[0041] 10g of methanol and 2.1g of a fluorinated surfactant with a perfluoropolyether structure (structural formula CF3OCF2OCF2OCF2OCF2COONH4) were mixed evenly at 60°C to obtain a water-locking inhibitor B.
[0042] 3. Preparation of fracturing fluid
[0043] Dissolve 2g of the prepared oleamide surfactant and 6g of the prepared erucamide surfactant in 150mL of warm water at 60℃ and stir until homogeneous to obtain a surfactant solution. Dissolve 1.5g of the water-locking inhibitor B prepared in step 3 and 1.4g of ammonium chloride in 40mL of water and slowly pour this solution into the surfactant solution at a rate of 2mL / s, stirring until homogeneous. Continue to add 0.05g of sodium bicarbonate and 0.8g of octadecyl 4-chlorobenzenesulfonate to the mixed solution and stir until homogeneous to obtain a mixed solution. Then dissolve 3.6g of sodium salicylate in 10mL of water and slowly add this sodium salicylate solution into the aforementioned mixed solution at a rate of 2mL / s, stirring until homogeneous to obtain the fracturing fluid B.
[0044] The temperature resistance and shear strength of the fracturing fluid B prepared in this embodiment were tested. Figure 2 For this fracturing fluid at 200℃ for 170 seconds -1 The temperature resistance and shear strength characteristic curves are shown below. From... Figure 1 It can be seen that the viscosity of the fracturing fluid prepared in this embodiment is still above 70 mPa.s at 200℃, indicating that the fracturing fluid has a temperature resistance of 200℃ and can meet the fracturing construction requirements of reservoirs with temperatures not higher than 200℃.
[0045] The surface tension of the fracturing fluid B prepared in this embodiment was measured using a surface tension meter and the strip method. The test temperature was 20°C, and the test result was 20.8 Nm / m. The relatively small surface tension value indicates that it can significantly reduce water lock damage caused by fracturing fluid.
[0046] Comparative Example 1:
[0047] In Comparative Example 1, all erucamide surfactants in the system of Example 1 were replaced with oleamide surfactants, i.e., the mass of oleamide surfactants added to the system was 8g. The rest of the preparation methods were the same as in Example 1, and fracturing fluid C was obtained.
[0048] The temperature resistance and shear strength of the prepared fracturing fluid C were tested. Figure 3 For this fracturing fluid at 200℃ for 170 seconds -1 The temperature resistance and shear strength characteristic curves are shown below. From... Figure 3It can be seen that the viscosity of the fracturing fluid prepared in this comparative example is only about 15 mPa·s at 200℃, and its temperature resistance is far inferior to that of Example 1.
[0049] Comparative Example 2:
[0050] Comparative Example 2 did not add water-locking inhibitors, and the rest of the preparation method was the same as in Example 2, to obtain fracturing fluid D.
[0051] The surface tension of the fracturing fluid D prepared in this embodiment was measured using a surface tension meter and the plate method. The test temperature was 20℃, and the test result was 31.4 Nm / m. The surface tension value is relatively large and cannot play a role in inhibiting water lock damage.
Claims
1. A high-temperature resistant, waterproof, fracturing fluid, characterized in that, It is made from the following components by weight: The composition includes 1-3% oleamide surfactants, 1-3% erucamide surfactants, 0.5-2.5% sodium salicylate, 0.2-0.8% water-locking inhibitors, 0.3-0.6% synergists, 0.01-0.04% pH adjusters, 0.5-1.0% clay stabilizers, and 89%-96% water.
2. The high-temperature resistant, waterproof, and fracturing fluid according to claim 1, characterized in that, The preferred content of the component by weight is: The ingredients are: 1-2% oleamide surfactant, 2-3% erucamide surfactant, 1-2% sodium salicylate, 0.5-0.8% water-locking inhibitor, 0.4-0.5% synergist, 0.02-0.03% pH adjuster, 0.5-0.7% clay stabilizer, and 90-95% water.
3. The high-temperature resistant, waterproof, and fracturing fluid according to claim 1 or 2, characterized in that, The water-locking inhibitor is a mixture of methanol and a fluorinated surfactant in a mass ratio of 1:0.1-0.
3.
4. The high-temperature resistant, waterproof, and fracturing fluid according to claim 3, characterized in that, The preferred mass ratio of methanol to fluorinated surfactant is 1:0.15-0.
25.
5. The high-temperature resistant, waterproof, and fracturing fluid according to claim 3, characterized in that, The fluorinated surfactant has a perfluoropolyether structure and is selected from the structural formula CF3CF2CF2OCF(CF3)CF2OCF(CF3)COONH4. One of CF3CF2OCF(CF3)CF2OCF(CF3)COONH4 and CF3OCF2OCF2OCF2OCCF2COONH4.
6. The high-temperature resistant, waterproof, and fracturing fluid according to claim 1 or 2, characterized in that, The synergist is octadecyl 4-methylbenzenesulfonate or octadecyl 4-chlorobenzenesulfonate.
7. The high-temperature resistant, waterproof, and fracturing fluid according to claim 1 or 2, characterized in that, The pH adjuster is potassium hydroxide or sodium bicarbonate.
8. The high-temperature resistant, waterproof, and fracturing fluid according to claim 1 or 2, characterized in that, The clay stabilizer is potassium chloride or ammonium chloride.
9. A method for preparing the high-temperature resistant, waterproof, and fracturing fluid according to any one of claims 1-8, characterized in that, Includes the following steps: S1: Dissolve a mixture of oleamide surfactants and erucamide surfactants in water to obtain solution A; dissolve a water-locking inhibitor and a clay stabilizer in water to obtain solution B; S2: Add solution B described in S1 to solution A, and stir to obtain mixed solution C; S3: Add pH adjuster and synergist to the mixed solution C described in S2, stir, then add sodium salicylate aqueous solution, and continue stirring to obtain the high-temperature resistant waterproof fracturing fluid.
10. The preparation method according to claim 9, characterized in that, In step S1, the preparation method of oleamide surfactants and erucamide surfactants includes the following steps: Industrial oleamide or erucamide is reacted with 3-chloropropanediol and propylene oxide. After the reaction is complete, the solvent is removed. Dichloromethane is added to dissolve the oleamide. After dissolution, it is added dropwise to excess ethyl acetate for recrystallization and purification. The supernatant is removed, and the solvent is removed to obtain oleamide surfactants or erucamide surfactants.
11. The preparation method according to claim 10, characterized in that, The industrial oleamide or erucamide is mixed with 3-chloropropanediol and propylene oxide in a ratio of 1:1:2 by mass.
12. The preparation method according to claim 10, characterized in that, The reaction requires heating in a water bath to 95°C and stirring under reflux for 20-24 hours.
13. The preparation method according to any one of claims 9-12, characterized in that, In S1, the mixture of oleamide surfactants and erucamide surfactants is dissolved in water at a temperature of 50-70°C.
14. The preparation method according to any one of claims 9-12, characterized in that, In S2, the rate at which solution B is added to solution A is 2-5 mL / s.
15. The preparation method according to any one of claims 9-12, characterized in that, In step S3, the sodium salicylate aqueous solution is added at a rate of 2-5 mL / s.
16. The application of the fracturing fluid according to any one of claims 1-8 in fracturing deep tight gas wells with a well temperature not exceeding 200°C.