Preparation method of slow-release solid acid rod for plugging removal operation of oil field

Abstract

The invention relates to a preparation method of a slow-release solid acid rod for oil field plug removal operation, and belongs to the technical field of oil field chemistry. The preparation method comprises the following steps: mixing water-soluble epoxy resin, water-insoluble epoxy resin, anhydride monomers, organic acid monomers and sulfamic acid to prepare a prepolymer, and on the basis, further reacting at high temperature to generate an esterification product until the esterification product is completely cured, thereby preparing the slow-release solid acid rod. A result test shows that the prepared slow-release solid acid rod has excellent slow-release and dissolving properties. The process for preparing the slow-release solid acid rod is simple, and the slow-release solid acid rod is convenient to transport and use and has a wide application prospect in oil field plug removal operation.

Description

Technical Field

[0001] The invention relates to a method for preparing a slow-release solid acid stick used for oilfield plugging removal operations, and belongs to the technical field of oilfield chemistry. Background Art

[0002] Oil is known as the "blood of industry" and plays a vital role in modern industrial society. It is not only related to a country's energy security, but also an important driving force for economic development. In order to meet the growing demand for oil in various fields, countries around the world are also increasing their efforts in oil extraction. In the process of oil field development, due to the deposition of minerals in water (such as calcium carbonate, calcium sulfate, silicate, etc.), the deposition of crude oil asphaltene and the corrosion of the well wall, the oil field water injection wells are blocked, which seriously affects the water injection efficiency of the oil field and the output of the oil wells, thus affecting the development effect of the entire oil field.

[0003] Acidizing plugging removal is one of the most commonly used and effective methods for oilfield development. It can significantly improve the production of oil wells and the injection capacity of water injection wells, and extend the production life of oil wells. Acidizing plugging removal mainly utilizes the chemical corrosiveness of acidic substances to dissolve mineral deposits that block the wellbore or formation, dredge the flow channel, and restore the seepage capacity of the formation. In the acidizing plugging removal process, commonly used acid types include hydrochloric acid, hydrofluoric acid, earth acid, and aminosulfonic acid. Among them, aminosulfonic acid, as a powdered solid acid, is safer and more convenient than other liquid acids, but it still has problems such as high storage requirements, difficult transportation, and many risks in use. Therefore, aminosulfonic acid is wrapped by wrapping materials to form an isolation layer to isolate it from external contact, and a solid acid stick with a size suitable for wellbore addition and long-term acid release performance is prepared. It has good practical significance and broad application prospects in the oilfield development plugging removal process. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a method for preparing a slow-release solid acid stick for oilfield unblocking operations. SUMMARY OF THE INVENTION

[0006] The present invention prepares a prepolymer by mixing a water-soluble epoxy resin, a water-insoluble epoxy resin, an anhydride monomer, an organic acid monomer and aminosulfonic acid, and then further reacts the prepolymer at a high temperature to generate an esterification product until it is completely cured to prepare a slow-release solid acid stick. Test results show that the prepared slow-release solid acid stick has excellent slow-release and solubility properties. DETAILED DESCRIPTION OF THE INVENTION

[0008] The technical solution of the present invention is as follows.

[0009] A method for preparing a slow-release solid acid stick for oilfield unblocking operations comprises the following steps:

[0010] (1) Preparation of prepolymer

[0011] In a flask equipped with a stirrer, a nitrogen tube and a thermometer, add a water-soluble epoxy resin, a water-insoluble epoxy resin, an anhydride monomer, an organic acid monomer, a cross-linking agent, a accelerator and aminosulfonic acid in sequence, stir until dissolved, pass nitrogen for 15 minutes, and react at 20-60°C for 1-5 hours to obtain; the mass ratio of the water-soluble epoxy resin, the water-insoluble epoxy resin, the anhydride monomer, the organic acid monomer, the cross-linking agent and the accelerator is 1:(0.1-1):(0.5-1.5):(0.2-1):(0.001-0.01):(0.001-0.05), and the ratio of the total mass of the water-soluble epoxy resin, the water-insoluble epoxy resin, the anhydride monomer, the organic acid monomer, the cross-linking agent and the accelerator to the mass of the aminosulfonic acid is 1:(0.1-10);

[0012] (2) Preparation of solid acid rods

[0013] Pour the prepolymer into a cylindrical mold, place it in an oven, control the temperature at 80-140°C, react for 6-24 hours, and cool and demould the product after it is completely solidified.

[0014] According to the present invention, preferably, the water-soluble epoxy resin in step (1) is

[0015]

[0016] Where a is 2 to 10;

[0017] Preferably, the water-insoluble epoxy resin is

[0018]

[0019] Where b is 0 to 5;

[0020] Preferably, the acid anhydride monomer is one or a mixture of two or more of maleic anhydride, tetrahydrophthalic anhydride, 2-butene-1-yl succinic anhydride, octenyl succinic anhydride, dodecenyl succinic anhydride, and acrylic anhydride;

[0021] Preferably, the organic acid monomer is one or a mixture of two or more of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and sorbic acid;

[0022] Preferably, the cross-linking agent is

[0023]

[0024] Where c is 1 to 8;

[0025] Preferably, the accelerator is one or a mixture of two or more of benzoic acid, p-toluenesulfonic acid, phosphoric acid, adipic acid, trifluoroacetic acid, and acetic acid;

[0026] Preferably, the mass ratio of the water-soluble epoxy resin, the water-insoluble epoxy resin, the anhydride monomer, the organic acid monomer, the crosslinking agent, and the accelerator is 1:(0.1-1):(0.5-1.5):(0.2-1):(0.001-0.01):(0.001-0.05);

[0027] Preferably, the ratio of the total mass of the water-soluble epoxy resin, the water-insoluble epoxy resin, the anhydride monomer, the organic acid monomer, the crosslinking agent, and the accelerator to the mass of the aminosulfonic acid is 1:(0.1-10);

[0028] Preferably, the reaction temperature is 20-60° C., and the reaction time is 1-5 h.

[0029] According to the present invention, preferably, the reaction temperature in step (2) is 80 to 140° C., and the reaction time is 6 to 24 hours.

[0030] The excellent effects of the present invention are as follows:

[0031] 1. The raw materials of the present invention are easily available, the reaction conditions are mild, the process is simple and safe, and large-scale industrial production can be realized.

[0032] 2. The solid acid stick prepared by the present invention contains epoxy resin and corresponding cross-linking agent, and after the two react and solidify, the solid acid stick is ensured to have good mechanical strength.

[0033] 3. The solid acid stick prepared by the present invention has a cylindrical structure, which is safer and more convenient to store, transport and use than aminosulfonic acid powder.

[0034] 4. The present invention utilizes the change in the amount of water-soluble epoxy resin and non-water-soluble epoxy resin, as well as the change in the amount of organic acid raw materials, to regulate the dissolution rate of the solid acid stick and achieve control of the sustained-release performance of the product.

[0035] 5. The raw materials of the present invention are solidified and formed through esterification reaction, and the good hydrolysis ability of the ester group under oil reservoir conditions is utilized to achieve the purpose of good solubility of the solid acid stick and less residue.

[0036] 6. The product prepared by the present invention is easy to store, transport and use, and meets the requirements of environmental protection. DETAILED DESCRIPTION

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0038] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0039] Embodiment 1:

[0040] (1) Preparation of prepolymer

[0041] In a flask equipped with a stirrer, a nitrogen tube and a thermometer, 40 g of a water-soluble epoxy resin (a is 3), 20 g of a water-insoluble epoxy resin (b is 3), 25 g of maleic anhydride, 15 g of acrylic acid, 0.1 g of a crosslinking agent (c is 2), 0.1 g of p-toluenesulfonic acid and 100 g of aminosulfonic acid were added in sequence, stirred until dissolved, nitrogen was introduced for 15 min, and reacted at 30° C. for 2 h to obtain a prepolymer;

[0042] (2) Preparation of solid acid rods

[0043] The prepolymer was poured into a cylindrical mold, placed in an oven, the temperature was controlled at 85°C, and the reaction was carried out for 18 hours. After the product was completely solidified, it was cooled and demolded to obtain a solid acid stick.

[0044] Embodiment 2:

[0045] As described in Example 1, the difference is that in step (1), the a of the water-soluble epoxy resin is 5 and the added amount is 50g.

[0046] Embodiment 3:

[0047] As described in Example 1, the difference is that in step (1), the a of the water-soluble epoxy resin is 6 and the added amount is 30 g.

[0048] Embodiment 4:

[0049] As described in Example 1, the difference is that in step (1), the amount of b of the non-water-soluble epoxy resin is 2 and the amount added is 40g.

[0050] Embodiment 5:

[0051] As described in Example 1, the difference is that in step (1), b of the non-water-soluble epoxy resin is 4 and the added amount is 30 g.

[0052] Embodiment 6:

[0053] As described in Example 1, the difference is that the anhydride monomers in step (1) are 15 g of maleic anhydride and 20 g of tetrahydrophthalic anhydride.

[0054] Embodiment 7:

[0055] As described in Example 1, the difference is that the anhydride monomers in step (1) are 20 g of tetrahydrophthalic anhydride and 20 g of dodecenylsuccinic anhydride.

[0056] Embodiment 8:

[0057] As described in Example 1, the difference is that the organic acid monomers in step (1) are 10 g of acrylic acid and 5 g of methacrylic acid.

[0058] Embodiment 9:

[0059] As described in Example 1, except that the organic acid monomers in step (1) are 12 g methacrylic acid and 7 g maleic acid.

[0060] Embodiment 10:

[0061] As described in Example 1, except that in step (1), the cross-linking agent c is 3 and the added amount is 0.3 g.

[0062] Embodiment 11:

[0063] As described in Example 1, except that in step (1), the cross-linking agent c is 6 and the added amount is 0.2 g.

[0064] Embodiment 12:

[0065] As described in Example 1, except that the promoter in step (1) is 0.1 g benzoic acid and 0.3 g p-toluenesulfonic acid.

[0066] Embodiment 13:

[0067] As described in Example 1, except that the promoter in step (1) is 0.2 g benzoic acid and 0.2 g acetic acid.

[0068] Embodiment 14:

[0069] As described in Example 1, except that the amount of aminosulfonic acid added in step (1) is 200 g.

[0070] Embodiment 15:

[0071] As described in Example 1, except that in step (1), the reaction temperature is 50° C. and the reaction time is 4 h.

[0072] Embodiment 16:

[0073] As described in Example 1, except that in step (2), the reaction temperature is 110° C. and the reaction time is 8 h.

[0074] Performance Evaluation

[0075] Simulated formation water was prepared according to the composition in Table 1. The solid slow-release acid stick was processed into a cylindrical shape (Φ4×6 cm) by a mold for later use.

[0076] (1) Sustained release performance test

[0077] The solid acid stick was placed in 1000 mL of simulated formation water and aged in an oven at 85°C. 5 mL of solution was taken out at regular intervals, and the acid concentration in the solution was determined by acid-base titration to calculate the acid release rate.

[0078] Solid acid stick acid release rate calculation formula:

[0079]

[0080] Where, RS is the release rate of solid sustained-release acid, %;

[0081] C x —Acid concentration of the solution after soaking for x time, mol / L;

[0082] C y —Acid concentration of the solution after 10 days of immersion, mol / L.

[0083] (2) Solubility test

[0084] The mass of the solid acid stick was weighed, and the solid acid stick was placed in 1000 mL of simulated formation water, and aged in an oven at 85° C. for 10 days. The residue was filtered out and dried, and then the mass of the residue was weighed.

[0085] Dissolved residual rate calculation formula:

[0086]

[0087] Wherein, RD is the residual dissolution rate of solid sustained-release acid, %;

[0088] m x —mass of residue, g;

[0089] m y —Mass of solid acid rod, g.

[0090] Table 1 Composition of simulated formation water

[0091]

[0092] Table 2 Sustained release and dissolution properties of different samples

[0093]

[0094] It can be seen from Table 2 that the acid release rate of the solid acid stick prepared by the present invention within 3 days of aging does not exceed 20%, and the acid release rate within 7 days of aging is more than 80%, which proves that it is concentratedly released within 3 to 7 days and has good sustained release performance; the dissolved residual rate within 10 days does not exceed 3%, which proves that it has good solubility performance.

Claims

1. A method for preparing a sustained-release solid acid stick comprises the following steps: (1) Preparation of prepolymer In a flask equipped with a stirrer, a nitrogen tube and a thermometer, add a water-soluble epoxy resin, a water-insoluble epoxy resin, an anhydride monomer, an organic acid monomer, a cross-linking agent, a accelerator and aminosulfonic acid in sequence, stir until dissolved, pass nitrogen for 15 minutes, and react at 20-60°C for 1-5 hours to obtain; the mass ratio of the water-soluble epoxy resin, the water-insoluble epoxy resin, the anhydride monomer, the organic acid monomer, the cross-linking agent and the accelerator is 1:(0.1-1):(0.5-1.5):(0.2-1):(0.001-0.01):(0.001-0.05), and the ratio of the total mass of the water-soluble epoxy resin, the water-insoluble epoxy resin, the anhydride monomer, the organic acid monomer, the cross-linking agent and the accelerator to the mass of the aminosulfonic acid is 1:(0.1-10); The water-soluble epoxy resin is Where a is 2 to 10; The non-water-soluble epoxy resin is Where b is 0 to 5; The acid anhydride monomer is one or a mixture of two or more of maleic anhydride, tetrahydrophthalic anhydride, 2-butene-1-yl succinic anhydride, octenyl succinic anhydride, dodecenyl succinic anhydride, and acrylic anhydride; The organic acid monomer is one or a mixture of two or more of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and sorbic acid; The cross-linking agent is Where c is 1 to 8; The accelerator is one or a mixture of two or more of benzoic acid, p-toluenesulfonic acid, phosphoric acid, adipic acid, trifluoroacetic acid, and acetic acid; (2) Preparation of solid acid rods Pour the prepolymer into a cylindrical mold, place it in an oven, control the temperature at 80-140°C, react for 6-24 hours, and cool and demould the product after it is completely solidified.

2. The method for preparing a sustained-release solid acid stick for oilfield unblocking according to claim 1, characterized in that: In step (1), the mass ratio of the water-soluble epoxy resin, the water-insoluble epoxy resin, the anhydride monomer, the organic acid monomer, the crosslinking agent and the accelerator is 1:(0.1-1):(0.5-1.5):(0.2-1):(0.001-0.01):(0.001-0.05).

3. The method for preparing a slow-release solid acid stick for oilfield unblocking according to claim 1, characterized in that: In step (1), the ratio of the total mass of the water-soluble epoxy resin, the water-insoluble epoxy resin, the anhydride monomer, the organic acid monomer, the crosslinking agent and the accelerator to the mass of the aminosulfonic acid is 1:(0.1-10).

4. The method for preparing a slow-release solid acid stick for oilfield unblocking according to claim 1, characterized in that: In step (1), the reaction temperature is 20-60° C. and the reaction time is 1-5 h.

5. The method for preparing a slow-release solid acid stick for oilfield unblocking according to claim 1, characterized in that: In step (2), the reaction temperature is 80-140° C. and the reaction time is 6-24 h.

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