Polyhydroxy amino carboxylic acid blocking remover as well as preparation method and application thereof

Abstract

The invention relates to the technical field of oil-water well blocking removal, and discloses a polyhydroxy amino carboxylic acid blocking remover and a preparation method and application thereof, and the polyhydroxy amino carboxylic acid blocking remover comprises the following raw materials: a polyhydroxy amino carboxylic acid complexing agent, deionized water, a pH buffer agent, a corrosion inhibition synergist and a permeation auxiliary agent; the prepared blocking remover hardly generates solid scale slag or secondary sediment in the scale dissolving process, effectively avoids the risk of secondary blocking, has thermal stability, can meet the use requirement in a high-temperature environment, can rapidly permeate into a compact scale layer and improve the scale dissolving efficiency and depth in cooperation with a penetrating agent, and uses a pH buffering agent to replace strong base, so that the blocking remover is environmentally friendly. After the pH of the system is adjusted, the corrosion inhibitor is matched, so that the corrosion of the blocking remover to equipment can be effectively prevented, the service life of the equipment for the oil-water well can be remarkably prolonged, the core raw materials used in the blocking remover are biodegradable, the environment-friendly requirement can be met, and the blocking remover is relatively friendly to the ecological environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil and water well plugging removal, and particularly relates to a multi-hydroxy amino carboxylic acid plugging removal agent and a preparation method and application thereof. BACKGROUND

[0002] In the process of oil and gas exploitation, oil and water well scaling is a common technical bottleneck that leads to a decrease in production rate and a sharp increase in maintenance cost. With the deepening of oilfield development, high-concentration calcium, magnesium, barium and strontium scaling ions in the formation water are prone to precipitate calcium sulfate, barium sulfate and other insoluble inorganic salt scales when the temperature and pressure fluctuate and when they are in contact with high-sulfate water. These dense scale layers are firmly deposited on the near-wellbore zone, perforation holes, downhole pump valves and the inner wall of the delivery pipe string, seriously blocking the oil and gas seepage channel, leading to a sharp decrease in single-well production, a rise in water injection pressure, and even causing deep-well pump seizure and production pipe string sanding and other malignant production accidents. In order to restore production capacity, well repair or acidizing and fracturing are often required, which not only increases the development cost but also seriously disrupts the production order. Therefore, finding an efficient and safe plugging removal technology is the key to ensuring long-term stable production of oil and gas fields.

[0003] At present, the mainstream chemical plugging removal technology mainly relies on strong acid and strong base dissolution. Although the strong acid system represented by hydrochloric acid can quickly dissolve carbonate scales and part of sulfate scales through chemical reaction, the reaction is uncontrolled and can easily cause corrosion of equipment. In addition, high-concentration calcium ions are released during the scale dissolution process, which can form scale mud in the formation and cause secondary deposition if not returned in time. In order to solve the above problems, the patent with publication number CN106811186B discloses an acidizing plugging removal agent. The acidizing plugging removal agent increases nitric acid, organic acid, penetrating agent and oil washing agent compared with conventional acidizing plugging removal agents, so as to improve the dissolution rate of scales and formation blockages, does not produce secondary deposition, and the added surfactant and penetrating agent can increase the effective action distance of the acid liquid, achieve the purpose of deep acidizing of the formation, reduce the reaction speed, prolong the effective reaction time of the acid, and at the same time, the surface tension between the acid liquid and the rock can be reduced to adjust the wettability of the rock and acid liquid contact surface, effectively realizing the return of residual acid liquid. The added demulsifier component can prevent the emulsion produced by the mixing of the plugging removal agent and the formation fluid from blocking the formation, can reduce the return resistance and avoid causing new pollution and blockage. However, the prepared plugging removal agent of the patent needs to be improved in terms of high-temperature resistance, and the plugging removal capacity is easily lost in a high-temperature environment. In addition, the use of strong acid and surfactant and other components will cause serious environmental burden, which does not meet the green and environmentally friendly concept. SUMMARY

[0004] The purpose of this invention is to provide a polyhydroxyaminocarboxylic acid unblocking agent, its preparation method and application, which solves the following technical problems: (1) Traditional strong acid or strong base unblocking systems are prone to secondary precipitation or large hard scale in the scale solution, which can easily cause deep well pump jamming and secondary blockage of oil production channels; (2) Traditional strong acid and strong base unblocking systems are corrosive to downhole tubing and tools, which will shorten the service life of equipment when used; (3) Existing unblocking agents are prone to dispersion and failure of complexing active ingredients under high temperature conditions, resulting in reduced complexing ability; (4) Traditional unblocking agents often use surfactants that are difficult to degrade or have ecotoxicity, which does not conform to the concept of environmental protection.

[0005] The objective of this invention can be achieved through the following technical solutions: A polyhydroxyaminocarboxylic acid-based unblocking agent comprises the following raw materials in parts by weight: 30-60 parts polyhydroxyaminocarboxylic acid complexing agent, 65-150 parts deionized water, 8-12 parts pH buffer, 1-3 parts corrosion inhibitor, and 0.2-0.5 parts penetration enhancer; wherein the polyhydroxyaminocarboxylic acid complexing agent is prepared by a click reaction of alkenylated gelatin with L-cysteine; wherein the alkenylated gelatin is prepared by a ring-opening reaction of gelatin with glycidyl methacrylate.

[0006] Furthermore, the pH buffer is a complex composed of sodium citrate and sodium bicarbonate in a mass ratio of 2.5-3.5:1-1.2.

[0007] Furthermore, the corrosion inhibitor is any one of sodium gluconate, sodium phytate, sodium tungstate, and sodium polyaspartate; the penetration aid is any one of alkyl glycoside APG0810, tea saponin, and sophorolipid.

[0008] Furthermore, the preparation method of the polyhydroxyaminocarboxylic acid complexing agent includes the following steps: S1: Add gelatin to a carbonate buffer solution, stir in a water bath at 45-55℃ for 30-45 min, add glycidyl methacrylate, heat to 60-65℃, stir at 200-300 rpm for 4-6 h, cool to room temperature and purify, collect the product to obtain alkenylated gelatin. S2: Add alkenylated gelatin to deionized water, stir and dissolve at room temperature, introduce nitrogen gas, add L-cysteine ​​and photoinitiator, irradiate with UV lamp for 2-2.5 h, separate and purify, collect the product to obtain polyhydroxyaminocarboxylic acid complexing agent.

[0009] In the scheme, the amino group in the gelatin structure undergoes ring-opening reaction with the epoxy group in the glycidyl methacrylate structure to obtain an alkenylated gelatin containing multiple hydroxyl groups in the structure; then, under the action of a photoinitiator and UV light, the alkenyl group in the alkenylated gelatin structure and the thiol group in the L-cysteine structure undergo click chemistry reaction to obtain a polyhydroxy aminocarboxylic acid complexing agent; the polyhydroxy aminocarboxylic acid complexing agent successfully introduces hydroxyl, carboxyl and amino functional groups on the natural gelatin skeleton through two steps, has excellent synergistic complexation with calcium, magnesium and strontium cations constituting sulfate scale, the carboxyl and amino groups can provide strong primary coordination sites, and the hydroxyl group can stabilize the complex structure through steric hindrance and hydrogen bonding; the gelatin as the skeleton has good adhesion and film-forming property in the solution, the molecules can effectively wet and have high molecular chain swelling effect, can strip the scale layer and synergistically act with the hydroxyl, carboxyl and amino functional groups on the molecular chain to form a double plugging removal mechanism, effectively improving the plugging removal efficiency of the plugging removal agent; and the formation of the three-dimensional network structure can in-situ wrap and stably disperse the generated metal complexes in the aqueous phase through the blocking between the molecular chains after complexing the metal ions, effectively preventing the generated complexes from colliding and aggregating to form insoluble precipitates or large scale residues, fundamentally solving the problem of secondary precipitation caused by traditional small molecule complexing agents at high concentrations, the polyhydroxy aminocarboxylic acid polymer has good high-temperature resistance and can meet the use requirements in high-temperature environments, and the complexing agent prepared from the biologically derived gelatin and L-cysteine in the scheme has good biocompatibility and is easy to degrade, and the complexing agent itself is neutral to weakly acidic, effectively avoiding the potential threat of strong acid and strong base to personnel and equipment.

[0010] Further, in step S1, the concentration of the carbonate buffer solution is 0.1-0.2 mol / L.

[0011] Further, in step S2, the photoinitiator is any one of photoinitiator 2959 and photoinitiator 307.

[0012] Further, in step S2, the power of the UV lamp is 35 W and the wavelength is 365 nm.

[0013] A preparation method of a polyhydroxy aminocarboxylic acid plugging removal agent, comprising the following steps: The polyhydroxy aminocarboxylic acid complexing agent is added to deionized water, stirred and dissolved at a temperature of 40-45°C, a pH buffer, an corrosion inhibitor synergist and a penetration aid are added, the pH is adjusted, and after mixing and stirring for 0.5-1 h, a plugging removal agent is obtained.

[0014] Further, adjusting the pH specifically refers to adjusting the pH to 10-10.5 using a potassium hydroxide solution with a concentration of 0.1-0.2 mol / L.

[0015] A kind of polyhydroxy amino carboxylic acid type plugging remover, the plugging remover is applied to remove inorganic salt scale plugging of oil-water well, and no secondary precipitate is produced in the process of plugging removal.

[0016] The beneficial effects of the present application are: The present application is prepared by preparing polyhydroxy amino carboxylic acid complexing agent to participate in the preparation process of plugging remover, so that the prepared plugging remover hardly produces solid scale residue or secondary precipitation in the scale dissolving process, effectively avoids the risk of secondary plugging, and has thermal stability, can meet the use demand in high temperature environment, can quickly penetrate into dense scale layer with the use of penetrating agent, improve the scale dissolving efficiency and depth, replace strong alkali with pH buffer to adjust the system pH to 10-10.5, and cooperate with corrosion inhibitor to effectively prevent the corrosion of plugging remover to equipment, significantly prolong the service life of oil-water well equipment, and the core raw material used in the present application is biodegradable, can meet the environmental protection requirements, and is more friendly to ecological environment.

[0017] Of course, implementing any product of the present application does not necessarily need to achieve all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed for the description of the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0019] Figure 1 The preparation flow chart of the polyhydroxy amino carboxylic acid type plugging remover in the present application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0021] The preparation method of the polyhydroxy amino carboxylic acid complexing agent in the embodiments of the present application and the comparative examples comprises the following steps: S1: 2g gelatin is added to 40ml carbonate buffer solution with a concentration of 0.1mol / L, stirred for 30min under 45℃ water bath, then 1.2g glycidyl methacrylate is added, the temperature is raised to 60℃, and stirred at a speed of 200rpm for 4h, then cooled to room temperature and purified, and the product is collected to obtain alkenylated gelatin; The content of double bond in the alkenylated gelatin is tested by iodometric method, and the specific detection method is as follows: 0.1 mol / L sodium thiosulfate solution, 10% potassium iodide solution and 1% starch solution are prepared; 20ml of carbon tetrachloride is placed in an iodometric flask, 1g of alkenylated gelatin is added as a sample, 10ml of bromine-potassium bromide solution is added, and after stirring and mixing, 5ml of potassium iodide solution and 5ml of deionized water are added, and after stirring, the standard sodium thiosulfate solution is used for titration, when the solution color changes, 1ml of starch solution is added, and the titration is continued to the end point, and a blank control is carried out at the same time; the following formula is used for calculation: the content of double bond in the sample (%) = (V0-V)C x M / 20m; in the formula, V0 is the volume of sodium thiosulfate solution consumed in the blank test, ml; V is the volume of sodium thiosulfate solution consumed in the titration of the sample, ml; C is the concentration of sodium thiosulfate solution, mol / L; M is the molar mass of the double bond part (g / mol); m is the mass of the sample, g; through calculation, the content of double bond in the alkenylated gelatin is 5.6%; S2: 2.6g of alkenylated gelatin is added to 50ml of deionized water, stirred and dissolved at room temperature, nitrogen is introduced, 1.5g of L-cysteine and 0.15g of photoinitiator 2959 are added, and a UV lamp with a power of 35W and a wavelength of 365nm is used for irradiation for 2h, and the product is collected after separation and purification to obtain a polyhydroxy aminocarboxylic acid complexing agent; The content of double bond in the polyhydroxy aminocarboxylic acid complexing agent is tested by iodometric method, and the specific detection method and steps S1 are the same, and through calculation, the content of double bond in the polyhydroxy aminocarboxylic acid complexing agent is 0.66%, which is significantly reduced compared with the content of double bond in the alkenylated gelatin, which is because the alkenyl group in the structure of the alkenylated gelatin reacts with the thiol group in the structure of L-cysteine to produce consumption; The content of sulfur element in the alkenylated gelatin and the polyhydroxy aminocarboxylic acid complexing agent is analyzed by using a Thermo type elemental analyzer, and it is found that the alkenylated gelatin does not contain sulfur element, and the content of sulfur element in the polyhydroxy aminocarboxylic acid complexing agent is 6.8%, which is because the alkenyl group in the structure of the alkenylated gelatin reacts with the thiol group in the structure of L-cysteine to introduce sulfur element into the polyhydroxy aminocarboxylic acid complexing agent. Example 1

[0022] Preparation of polyhydroxy aminocarboxylic acid type plugging remover 30 parts of polyhydroxy aminocarboxylic acid complexing agent are added to 65 parts of deionized water, stirred and dissolved at 40℃, 8 parts of a compound composed of sodium citrate and sodium bicarbonate with a mass ratio of 2.5:1, 1 part of sodium gluconate, and 0.2 parts of alkyl glycoside APG0810 are added, a 0.1mol / L potassium hydroxide solution is used to adjust the pH to 10, and after mixing and stirring for 0.5h, a plugging remover is obtained. Example 2

[0023] Preparation of polyhydroxy amino carboxylic acid plugging remover 45 parts of polyhydroxy amino carboxylic acid complexing agent were added into 100 parts of deionized water, and stirred and dissolved at 42℃, then 10 parts of a compound composed of sodium citrate and sodium bicarbonate with a mass ratio of 3:1.1, 2 parts of sodium phytate, and 0.35 parts of tea saponin were added, a potassium hydroxide solution with a concentration of 0.15 mol / L was used to adjust the pH to 10.2, and after stirring for 0.8 h, the plugging remover was obtained. Example 3

[0024] Preparation of polyhydroxy amino carboxylic acid plugging remover 60 parts of polyhydroxy amino carboxylic acid complexing agent were added into 150 parts of deionized water, and stirred and dissolved at 45℃, then 12 parts of a compound composed of sodium citrate and sodium bicarbonate with a mass ratio of 3.5:1.2, 3 parts of sodium tungstate, and 0.5 parts of sophorolipid were added, a potassium hydroxide solution with a concentration of 0.2 mol / L was used to adjust the pH to 10.5, and after stirring for 1 h, the plugging remover was obtained.

[0025] Comparative Example 1 Preparation of plugging remover 45 parts of disodium ethylenediaminetetraacetate were added into 100 parts of deionized water, and stirred and dissolved at 42℃, then 10 parts of a compound composed of sodium citrate and sodium bicarbonate with a mass ratio of 3:1.1, 2 parts of sodium phytate, and 0.35 parts of tea saponin were added, a potassium hydroxide solution with a concentration of 0.15 mol / L was used to adjust the pH to 10.2, and after stirring for 0.8 h, the plugging remover was obtained.

[0026] Comparative Example 2 Preparation of plugging remover 45 parts of polyhydroxy amino carboxylic acid complexing agent were added into 100 parts of deionized water, and stirred and dissolved at 42℃, then 2 parts of sodium phytate and 0.35 parts of tea saponin were added, and after stirring for 0.8 h, the plugging remover was obtained.

[0027] Performance detection ①The plugging removers prepared in Examples 1-3 and Comparative Examples 1-2 were used as samples for corrosion resistance detection, and the specific operation was as follows: N80 steel pieces with a size of 50mm×10mm×3mm were cut, polished with sandpaper, cleaned with acetone by ultrasonic, dried, weighed, and then completely immersed in 80℃ sample solution, 15% hydrochloric acid solution, and 10% sodium hydroxide solution for 72 h, respectively, then the surface corrosion products were cleaned with deionized water, dried, and weighed, and the corrosion rate was calculated according to the following formula: (weight loss×365) / area×days×steel density; the specific detection results are shown in Table 1 below: Table 1 Corrosion performance detection Corrosion rate (mm / a) Surface appearance Example 1 0.0009 Surface bright without corrosion Example 2 0.0007 Surface bright without corrosion Example 3 0.0008 Surface bright without corrosion Comparative Example 1 0.096 Surface with dark film, local pitting Comparative Example 2 0.053 Surface with dull and uneven film, sparse pitting Hydrochloric acid solution 7.85 Severe corrosion, large amount of black corrosion product Sodium hydroxide solution 1.66 Surface corrosion, uniform thinning From Table 1, it can be seen that the samples prepared in Examples 1-3 all have excellent corrosion protection effect. The corrosion protection effect of the sample prepared in Comparative Example 1 using disodium ethylenediaminetetraacetate as a complexing agent for the plug remover is better than that of the strong acid and strong base solution, but is still inferior to that of the examples. The sample prepared in Comparative Example 2 is not subjected to pH control, and it can be seen that the corrosion protection capability is inferior to that of the examples, which is due to the fact that although a polyhydroxy aminocarboxylic acid complexing agent is used, the pH of the plug remover is not regulated.

[0028] ②The plug removers prepared in Examples 1-3 and Comparative Examples 1-2 are used as samples to test the scale dissolving performance, and the specific operation is as follows: a calcium sulfate disc (purity > 98%) with a thickness of 2 mm and a diameter of 25 mm is dried and weighed, and the initial mass is recorded as m0. 100 ml of the sample is placed in a reaction bottle with a condensation reflux device, heated to 80°C, and immersed in the calcium sulfate disc. The temperature is kept constant for 24 h. After the reaction is completed, the disc is taken out and the surface is washed with deionized water. The disc is dried in a vacuum oven at 60°C until it is weighed. The remaining mass is recorded as m1. At the same time, the state of the solution in the reaction bottle is observed, and a 0.45 μm filter membrane is used to filter the solution. The filter membrane is dried at 105°C and weighed. It is detected whether solid particles are precipitated. The scale dissolving rate is calculated according to the formula: scale dissolving rate = (m0-m1) x 100% / m0. The specific test results are shown in Table 2. Table 2: Scale dissolving rate and secondary precipitation observation Dissolution rate / % Solution and scale morphology Example 1 98.6 Solution clear, scale completely disappeared Example 2 99.2 Solution clear, scale completely disappeared Example 3 98.9 Solution clear, scale completely disappeared Comparative Example 1 84.3 White suspended matter in solution, scale partially dissolved, 0.08 g solid particles detected on filter membrane Comparative Example 2 94.1 Solution slightly turbid, scale dispersed evenly From Table 2, it can be seen that the scale dissolving rate of the samples prepared in Examples 1-3 is all above 98.5%, and the solution is clear after the reaction without solid particles precipitating. The scale dissolving rate of the sample prepared in Comparative Example 1 is only 84.3%, and secondary precipitation occurs. The solution of the sample prepared in Comparative Example 2 is slightly turbid, which is inferior to the examples because the pH is not controlled.

[0029] ③The plug removers prepared in Example 2 and Comparative Example 1 are used as samples and placed in a high-temperature and high-pressure reaction kettle under the conditions of a temperature of 120°C and a pressure of 5 MPa for aging for 72 h. After cooling to room temperature, the scale dissolving rate of the aged samples is tested using the method of detection ②, and the samples before aging are compared. The test results are shown in Table 3. Table 3: Scale dissolving rate of plug removers after aging Dissolution rate / % before aging Dissolution rate / % after aging Retention rate / % Example 2 99.2 98.5 99.3 Comparative Example 1 Comparative Example 2 84.3 69.2 82.1 From Table 3, it can be seen that the scale dissolving rate of the plug remover prepared in Example 2 after aging is maintained at 99.3%, and the performance has almost no decay. The scale dissolving rate of the plug remover prepared in Comparative Example 1 after aging is only 82.1%, which cannot meet the use requirements in high-temperature environment.

[0030] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0031] The above is only an example and description of the concept of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or adopt similar ways to replace them, as long as they do not deviate from the scope defined by the concept of the application.

Claims

1. A multi-hydroxy amino carboxylic acid type plug remover, characterized by, The method comprises the following raw materials by weight: 30-60 parts of polyhydroxy aminocarboxylic acid complexing agent, 65-150 parts of deionized water, 8-12 parts of pH buffer, 1-3 parts of corrosion inhibitor synergist, and 0.2-0.5 parts of penetration aid.

2. The polyhydroxyamino carboxylic acid-based plug-breaking agent according to claim 1, characterized by, The pH buffer is a composite of sodium citrate and sodium bicarbonate in a mass ratio of 2.5-3.5:1-1.

2.

3. The polyhydroxyamino carboxylic acid-based plug breaking agent according to claim 1, characterized by, The corrosion inhibitor synergist is any one of sodium gluconate, sodium phytate, sodium tungstate, and sodium polyaspartate; and the penetration aid is any one of alkyl glycoside APG0810, tea saponin, and sophorolipid.

4. The polyhydroxyamino carboxylic acid-based plug breaking agent according to claim 1, characterized by, The method for preparing the polyhydroxy aminocarboxylic acid complexing agent comprises the following steps: S1: gelatin is added to a carbonate buffer solution, stirred at 45-55 DEG C for 30-45 min, glycidyl methacrylate is added, the temperature is raised to 60-65 DEG C, and stirring is carried out at a rotation speed of 200-300 rpm for 4-6 h, and then the product is collected after purification to obtain alkynylated gelatin; S2: the alkynylated gelatin is added to deionized water, stirred and dissolved at room temperature, nitrogen is introduced, L-cysteine and a photoinitiator are added, and the product is collected after separation and purification by irradiation with a UV lamp for 2-2.5 h to obtain the polyhydroxy aminocarboxylic acid complexing agent.

5. The polyhydroxyamino carboxylic acid-based cleanup agent according to claim 4, characterized by, In step S1, the concentration of the carbonate buffer solution is 0.1-0.2 mol / L.

6. The polyhydroxyamino carboxylic acid based cleanup agent of claim 4, wherein, In step S2, the photoinitiator is any one of photoinitiator 2959 and photoinitiator 307.

7. The polyhydroxyamino carboxylic acid based cleanup agent of claim 4, wherein, In step S2, the power of the UV lamp is 35 W, and the wavelength is 365 nm.

8. The preparation method of the polyhydroxyaminocarboxylic acid unblocking agent as described in claim 1, characterized in that, The method comprises the following steps: The polyhydroxy aminocarboxylic acid complexing agent is added to deionized water, stirred and dissolved at a temperature of 40-45 DEG C, a pH buffer, a corrosion inhibitor synergist, and a penetration aid are added, the pH is adjusted, and then the product is obtained after stirring for 0.5-1 h.

9. The preparation method of a polyhydroxyaminocarboxylic acid unblocking agent according to claim 8, characterized in that, The pH is adjusted by using a potassium hydroxide solution with a concentration of 0.1-0.2 mol / L to adjust the pH to 10-10.

5.

10. A polyhydroxyaminocarboxylic acid-based blocking remover as claimed in any one of claims 1 to 9, characterized in that, The plugging remover is applied to remove inorganic salt scale plugging in oil and water wells, and no secondary precipitate is generated during the plugging removal process.

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