Efficient composite drag-reducing and injection-increasing agent and preparation method and application thereof

Abstract

The invention discloses an efficient composite drag-reducing and injection-increasing agent and a preparation method and application thereof, and belongs to the technical field of oilfield water injection exploitation. The drag-reducing and injection-increasing agent comprises the following raw materials in percentage by mass: 10%-15% of a scale dissolving agent, 3%-5% of a gemini surfactant, 1%-3% of a degradation agent, 10%-20% of a mutual solvent, 0.5%-1% of a solubilizer and the balance of water. The adhesive force of crude oil on the rock surface can be effectively reduced, the wettability of the rock surface is changed, and the seepage resistance is reduced. The crude oil stripped from the rock surface is dispersed into small oil drops under the action of the surfactant, and the flowing capacity of the crude oil passing through the throat is improved, so that the reservoir permeability is improved, the stratum is dredged, the oil well liquid supply capacity is recovered, and normal water injection of a water well is achieved. And the pressure of the water injection well can be effectively reduced by more than 30% when the water injection well is blocked by oil stains caused by formation scaling and high residual oil saturation and long-term produced water reinjection.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield water injection and exploitation, and particularly relates to a high-efficiency composite drag-reducing and injection-increasing agent, a preparation method thereof, and an application thereof. Background Art

[0002] After waterflooding an oilfield, inorganic scale forms in the formation due to incompatibility between the injected water and the formation water. Simultaneously, some produced water quality issues can lead to organic matter accumulation in the formation, clogging the throat. Furthermore, asphaltene precipitates from the crude oil, blocking the formation's seepage channels and causing increased injection pressure, ultimately leading to underfill. Conventional acidification and plugging measures are too short-lived, resulting in a rapid increase in injection pressure after construction.

[0003] Several solutions have been proposed in the prior art to address these issues. For example, patent publication number CN 116925725A proposes a drag-reducing and injection-enhancing oil displacement agent system. The active ingredients include 26% to 35% aminocarboxylic acid chelating agent, 10% to 14% penetrant, 12% to 16% amphoteric surfactant, 14% to 18% nonionic surfactant, 18% to 22% mutual solvent, and the balance water. This system effectively reduces the adhesion of crude oil to the rock surface, thereby improving its flow through the throat and increasing reservoir permeability, enabling normal water injection into the well.

[0004] Patent publication number CN109762548A proposes a pressure-reducing and injection-enhancing oil displacement agent for low-permeability oil fields containing gemini surfactants, which includes: gemini-type silicone surfactants, polyoxyethylene sorbitan monooleate, chelating agents, bio-acids, scale inhibitors, and water; this invention can effectively prevent metal ion precipitation from damaging the formation.

[0005] CN104194744A proposes a drag reducer for drilling fluid and its preparation method. The preparation comprises 0.5% to 2% cationic gemini surfactant, 1% to 2% quaternary ammonium salt cationic surfactant, 0.5% to 1% sulfide oil, 20% to 25% polyglucoside aqueous solution, and the remainder white oil. The sulfide oil is added to the white oil at a temperature of 50°C to 60°C and stirred for 1 to 2 hours. The cationic gemini surfactant and quaternary ammonium salt cationic surfactant are then added in sequence and stirred for 2 to 4 hours. The polyglucoside aqueous solution is then added and stirred for 2 to 4 hours. The mixture is then concentrated at a temperature of 100°C to 120°C for 1 hour to obtain the drag reducer for drilling fluid. The drag reducer is suitable for reducing frictional resistance during the drilling of horizontal wells and extended reach wells, and is particularly effective in solid-free, low-solids, and clay-free drilling fluid systems.

[0006] However, although the above-mentioned chemical pressure-reducing and injection-increasing agents can reduce the oil-water interfacial tension, increase the water phase permeability and the migration speed of the oil-water microemulsion, or prevent the formation of scale to achieve the purpose of reducing the pressure and increasing the injection of water injection wells in low permeability oil fields, they cannot remove inorganic scale and organic matter at the same time. Summary of the Invention

[0007] In view of the above problems, the present invention proposes a high-efficiency composite drag reducing and injection-increasing agent, which comprises the following raw materials in percentage by mass:

[0008] 10% to 15% scale dissolving agent, 3% to 5% gemini surfactant, 1% to 3% degradation agent, 10% to 20% mutual solvent, 0.5% to 1% solubilizer and the balance water.

[0009] Furthermore, the scale dissolving agent is a mixed aqueous solution of 50 wt.% fluoboric acid and 38 wt.% hydrochloric acid.

[0010] Furthermore, the mixing volume ratio of the fluoroboric acid and the hydrochloric acid is 35-40%:15-18%.

[0011] Furthermore, the gemini surfactant is a diphenyl ether water-soluble gemini surfactant, sodium dodecyl diphenyl ether disulfonate;

[0012] The degradation agent is poly 3-hydroxyalkanoate.

[0013] Furthermore, the mutual solvent is propylene glycol methyl ether.

[0014] Furthermore, the solubilizing agent is diisopropylethylamine.

[0015] On the other hand, the present invention provides a method for preparing a high-efficiency composite drag reducing and injection-increasing agent, the preparation method comprising the following steps:

[0016] Add the scale dissolving agent, gemini surfactant, degradation agent, solubilizer and water in sequence and stir;

[0017] After stirring, a mutual solvent is added, and stirring is continued to obtain the high-efficiency composite drag reducing and injection-increasing agent.

[0018] Furthermore, during the stirring process, the reaction temperature is controlled at 15° C.-40° C., and the stirring rate is 300 r / min-800 r / min.

[0019] In addition, the present invention also proposes the application of the high-efficiency composite drag reducing and injection-increasing agent in water injection wells.

[0020] Furthermore, the application is specifically as follows: the high-efficiency composite drag reducing and injection-increasing agent is formulated into a specific concentration and then pumped into a water injection well column.

[0021] Beneficial effects of the present invention:

[0022] The high-efficiency composite drag-reducing and injection-increasing agent provided by the present invention can be used to dissolve inorganic scale blockages in the near-wellbore area of ​​the dissolving formation, thereby reducing seepage resistance; dissolving organic matter and asphaltene precipitated in the early stage, further clearing the formation seepage channels; reducing the adhesion of crude oil to the rock surface, changing the wettability of the rock surface, thereby increasing the reservoir permeability, clearing the formation, restoring the oil well's fluid supply capacity, and achieving normal water injection in the water well.

[0023] The high-efficiency composite drag-reducing and injection-increasing agent provided by this invention effectively reduces the adhesion of crude oil to rock surfaces, altering the wettability of the rock surface, thereby reducing seepage resistance. The crude oil stripped from the rock surface is dispersed into small droplets by the action of surfactants, improving its ability to flow through the throat, thereby increasing reservoir permeability, dredging the formation, restoring the fluid supply capacity of the oil well, and enabling normal water injection into the well.

[0024] The high-efficiency composite drag reducing and injection-increasing agent of the present invention is used for injection wells with poor water quality, high formation scaling and residual oil saturation, and wells blocked by oil pollution caused by long-term produced water reinjection, and can effectively reduce the pressure of the injection well by more than 30%.

[0025] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 The figure shows the dissolution effect of the high-efficiency composite drag reducing and injection-increasing agent and conventional acid solution on calcium carbonate in the embodiment of the present invention. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0029] The high-efficiency composite drag reducing and injection-increasing agent proposed by the present invention is composed of the following raw materials:

[0030] 10% to 15% scale dissolving agent; 3% to 5% gemini surfactant; 1% to 3% degradation agent; 10% to 20% mutual solvent; 0.5% to 1% solubilizing agent and the balance water.

[0031] The scale dissolving agent is a mixed aqueous solution of 50 wt.% fluoboric acid and 38 wt.% hydrochloric acid, wherein the mixing ratio of fluoboric acid to hydrochloric acid is 35-40%:15-18%. The scale dissolving agent can remove inorganic scale such as calcium carbonate through the acid dissolving ability.

[0032] The gemini surfactant is a diphenyl ether water-soluble gemini surfactant sodium dodecyl diphenyl ether disulfonate, which can effectively reduce the adhesion of crude oil on the rock surface, change the wettability of the rock surface, and reduce seepage resistance.

[0033] The degradation agent is poly 3-hydroxyalkanoate, which can effectively degrade waxy asphaltenes and improve the flowability of crude oil through the throat.

[0034] The mutual solvent is propylene glycol methyl ether, which can dissolve oil and water in each other and clean the residual oil-soluble surfactant in the formation.

[0035] The solubilizer is diisopropylethylamine, which improves the mutual solubility of the scale dissolving agent, the degradation agent and other agents, and improves the overall performance of the agents.

[0036] Example 1

[0037] This embodiment provides a high-efficiency composite drag-reducing and injection-increasing agent and a preparation method thereof. The raw material composition of the high-efficiency composite drag-reducing and injection-increasing agent includes: 10% scale dissolving agent (V (fluoroboric acid): V (hydrochloric acid) = 35%:15%); 3% sodium dodecyl diphenyl ether disulfonate; 1% poly 3-hydroxyalkanoate; and 75.5% water. These are added sequentially to a reactor, a stirring device is turned on, and the reactor temperature is raised to 50° C., reacted for 30 minutes, and then 10% propylene glycol methyl ether and 0.5% diisopropyl ethylamine are added. The temperature is then cooled to room temperature to obtain the high-efficiency composite drag-reducing and injection-increasing agent.

[0038] During the entire preparation process, if the temperature in the reactor is too low, for example, when the temperature is 10°C, the viscosity of the agent increases, resulting in prolonged dissolution time and insufficient dissolution; and when the temperature in the reactor is too high, for example, when the temperature exceeds 60°C, part of the agent, such as fluoroboric acid, will volatilize. The stirring time for the two times is 15-40 minutes respectively.

[0039] If the mutual solvent is added before the degradation agent and solubilizer during the preparation process, it is found that the drug added later cannot be dissolved.

[0040] The performance of the high-efficiency composite drag reducing and injection-increasing agent prepared in this embodiment was tested indoors. The specific test items included: appearance, surface tension, descaling rate, interfacial tension, and pressure reduction rate. The test methods for each item are as follows:

[0041] Appearance test method: take 50mL of sample into a 100mL colorimetric tube and visually observe the external state of the high-efficiency composite drag reducing and injection-increasing agent;

[0042] The test method for descaling rate is as follows:

[0043] Record the mass of medium-speed quantitative filter paper (weigh after drying to an accuracy of 0.0001g) as m0 and set aside.

[0044] In a 250 mL stoppered Erlenmeyer flask, accurately weigh 1.0 ± 0.01 g of a mixed scale sample (a mixture of calcium carbonate, calcium sulfate, and barium sulfate in a mass ratio of 1:1:1) and record its mass as m1.

[0045] Add 25.00g of high-efficiency composite drag reducing and injection agent and 200g of water, stir evenly, place in a 60℃ water bath, leave for 1h, and after the reaction is completed, filter the solution with medium-speed quantitative filter paper. Put the filter residue and filter paper into a 105℃ oven together. After 2h, take them out and put them in a desiccator. After 30min, weigh and record their mass as m2. The descaling rate calculation formula is as follows:

[0046]

[0047] Where C represents the descaling rate, %; m1 is the mass of the scale sample before the test, g; m0 is the mass of the filter paper, g; and m2 is the mass of the filter residue and filter paper after the test, g.

[0048] The test method for interfacial tension is as follows:

[0049] Use tap water to prepare 0.1%, 0.15%, 0.2%, 0.25% concentration of high-efficiency composite drag reducing and injection agent aqueous solutions, and test them according to the interfacial tension method in SY / T 5370-1999 "Surface and interfacial tension determination method" at a temperature of 50°C and a rotation speed of 5000r / min. The lowest interfacial tension is taken as the test result.

[0050] The test method for the pressure reduction rate is as follows:

[0051] The test was carried out in accordance with the pressure reduction rate method of Q / SH10202252-2014 "Technical Requirements for Surfactants for Pressure Reduction and Injection Enhancement". The test liquid was a 0.2% by mass aqueous solution of a high-efficiency composite drag reduction and injection enhancement agent; the test temperature was 50°C.

[0052] The high-efficiency composite drag reducing and injection-increasing agent prepared in Example 1 was subjected to quality technical tests according to the above test method. The results are shown in Table 1:

[0053] Table 1 Quality technical test results

[0054] Test items Test results Appearance Homogeneous transparent liquid surface tension 28 Descaling rate 95.3％ interfacial tension <![CDATA[0.65×10 -2 ]]> Blood pressure reduction rate 38.3％

[0055] On-site test results:

[0056] The high-efficiency composite drag reducing and injection-increasing agent prepared in this embodiment was used to construct two insufficiently injected water injection wells in the ZB oilfield of Changqing Oilfield. After injecting 50 cubic meters of the agent, normal water injection was carried out. The implementation effect is shown in Table 2.

[0057] Table 2 Changqing Oilfield on-site construction data

[0058]

[0059] Example 2

[0060] This embodiment provides a high-efficiency composite drag-reducing and injection-increasing agent and a preparation method thereof. The raw materials of the high-efficiency composite drag-reducing and injection-increasing agent include: 15% scale dissolving agent (V (fluoroboric acid): V (hydrochloric acid) = 35%: 15%); 5% sodium dodecyl diphenyl ether disulfonate; 3% poly (3-hydroxyalkanoate); and 56% water, which are added sequentially to a reactor. The stirring device is turned on, and the reactor temperature is raised to 50°C. After reacting for 30 minutes, 20% propylene glycol methyl ether and 1% diisopropyl ethylamine are added, and the temperature is then cooled to room temperature to obtain the high-efficiency composite drag-reducing and injection-increasing agent.

[0061] The performance of the high-efficiency composite drag reducing and injection-increasing agent prepared in this embodiment was tested indoors according to the test method in Example 1. The quality and technical test results are shown in Table 3:

[0062] Table 3 Quality technical test results

[0063] Test items Test results Appearance Homogeneous transparent liquid surface tension 24 Descaling rate 97.4％ interfacial tension <![CDATA[0.48×10 -2 ]]> Blood pressure reduction rate 31.2％

[0064] Field test results: The high-efficiency composite drag reducing and injection-increasing agent prepared in this embodiment was used to construct two insufficiently injected water injection wells in the HJ oilfield of Changqing Oilfield. After injecting 30 cubic meters of the agent, normal water injection was carried out. The implementation effect is shown in Table 4.

[0065] Table 4 Changqing Oilfield on-site construction data

[0066]

[0067] Example 3

[0068] The present invention provides a high-efficiency composite drag-reducing and injection-increasing agent and a preparation method thereof. The raw materials of the high-efficiency composite drag-reducing and injection-increasing agent include: 13% scale dissolving agent (V (fluoroboric acid): V (hydrochloric acid) = 35%: 15%); 4% sodium dodecyl diphenyl ether disulfonate; 2% poly (3-hydroxyalkanoate); and 65.4% water, which are sequentially added to a reactor. The stirring device is turned on, and the reactor temperature is raised to 50°C. After reacting for 30 minutes, 15% propylene glycol methyl ether and 0.6% diisopropyl ethylamine are added, and the mixture is then cooled to room temperature to obtain the high-efficiency composite drag-reducing and injection-increasing agent.

[0069] The performance of the high-efficiency composite drag reducing and injection-increasing agent prepared in this example was tested indoors according to the test method in Example 1. The quality and technical test results are shown in Table 5:

[0070] Table 5 Quality technical test results

[0071] Test items Test results Appearance Homogeneous transparent liquid surface tension 26 Descaling rate 96.4％ interfacial tension <![CDATA[0.59×10 -2 ]]> Blood pressure reduction rate 30.3％

[0072] On-site test results:

[0073] The high-efficiency composite drag reducing and injection-increasing agent prepared in this embodiment was used to construct two insufficiently injected water injection wells in the AS oil field of Changqing Oilfield. After injecting 40 cubic meters of the agent, normal water injection was carried out. The implementation effect is shown in Table 6.

[0074] Table 6 Changqing Oilfield on-site construction data

[0075]

[0076] The construction results of Examples 1-3 show that the above-mentioned high-efficiency composite drag-reducing and injection-increasing agent of this embodiment can effectively dissolve inorganic scale blockage in the near-wellbore area of ​​the formation, reduce seepage resistance; dissolve organic matter and asphaltene precipitated in the early stage, further dredge the formation seepage channels; reduce the adhesion of crude oil on the rock surface, change the wettability of the rock surface, thereby increasing the reservoir permeability, dredging the formation, restoring the oil well's fluid supply capacity, and achieving normal water injection in the water well, and has great practical application value.

[0077] Example 4 A high-efficiency composite drag reducing and injection-increasing agent was prepared in the same manner as in Example 1, except that the mixing volume ratio of fluoroboric acid and hydrochloric acid in the scale dissolving agent was 40:15; the construction well number was C63-69.

[0078] Example 5 A high-efficiency composite drag reducing and injection-increasing agent was prepared according to the same method as Example 1, except that the mass percentage of the scale dissolving agent was 20% and the construction well number was C38-33.

[0079] Example 6 A high-efficiency composite drag reducing and injection-increasing agent was prepared according to the same method as Example 1, except that the mutual solvent was ethylene glycol butyl ether and the construction well number was C28-98.

[0080] The high-efficiency composite drag reducing and injection-increasing agent prepared in Examples 4-6 was used to construct three insufficiently injected water injection wells in the AS oilfield of Changqing Oilfield. After injecting 50 cubic meters of the agent, normal water injection was resumed. The implementation results of the three wells are shown in Table 7.

[0081] Table 7 Changqing Oilfield on-site construction data

[0082]

[0083] Comparative Example 1 is different from Example 1 in that the drag reduction and injection enhancement oil displacement agent proposed in CN116925725A was used to construct two under-injection water injection wells in the ZB oilfield of Changqing Oilfield. The agent concentration was the same, and normal water injection was carried out after injecting 50 cubic meters of the agent. The implementation effect is shown in Table 8.

[0084] Table 8 On-site construction data of Changqing Oilfield

[0085]

[0086] Comparative Example 2: The high-efficiency composite drag reducing and injection-increasing agent prepared in Example 1 was configured into different concentrations to dissolve organic calcium carbonate in the near-wellbore zone of the formation. The dissolution rate was compared with the dissolution rate of organic calcium carbonate in the near-wellbore zone of the formation using conventional acid solution. Figure 1 As shown in the figure, the horizontal axis is the concentration of the agent, and the vertical axis is the dissolution rate of calcium carbonate. It can be seen that the high-efficiency composite drag reducing and injection-increasing agent proposed in the present invention has a higher dissolution rate of calcium carbonate than conventional acid (a mixture of hydrofluoric acid and hydrochloric acid). When the acid concentration is 5%, the dissolution rate of calcium carbonate by the scale dissolving agent proposed in the present invention reaches 95.8%.

[0087] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-efficiency composite drag reducing and injection-increasing agent, characterized in that: The drag reducing and injection-increasing agent comprises the following raw materials in percentage by mass: 10% to 15% scale dissolving agent, 3% to 5% gemini surfactant, 1% to 3% degradation agent, 10% to 20% mutual solvent, 0.5% to 1% solubilizer and the balance water.

2. The high-efficiency composite drag reducing and injection-increasing agent according to claim 1, characterized in that: The scale dissolving agent is a mixed aqueous solution of 50 wt.% fluoroboric acid and 38 wt.% hydrochloric acid.

3. The high-efficiency composite drag reducing and injection-increasing agent according to claim 2, characterized in that: The mixing volume ratio of the fluoroboric acid and the hydrochloric acid is 35-40%:15-18%.

4. The high-efficiency composite drag reducing and injection-increasing agent according to claim 1, characterized in that: The gemini surfactant is a diphenyl ether water-soluble gemini surfactant, sodium dodecyl diphenyl ether disulfonate; The degradation agent is poly 3-hydroxyalkanoate.

5. The high-efficiency composite drag reducing and injection-increasing agent according to claim 1, characterized in that: The mutual solvent is propylene glycol methyl ether.

6. The high-efficiency composite drag reducing and injection-increasing agent according to claim 1, characterized in that: The solubilizing agent is diisopropylethylamine.

7. The method for preparing the high-efficiency composite drag reducing and injection-increasing agent according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: Add the scale dissolving agent, gemini surfactant, degradation agent, solubilizer and water in sequence and stir; After stirring, a mutual solvent is added, and stirring is continued to obtain the high-efficiency composite drag reducing and injection-increasing agent.

8. The method for preparing a high-efficiency composite drag reducing and injection-increasing agent according to claim 7, characterized in that: During the stirring process, the reaction temperature is controlled at 15°C-40°C, and the stirring rate is 300r / min-800r / min.

9. Use of the high-efficiency composite drag-reducing and injection-increasing agent according to any one of claims 1 to 6 or the high-efficiency composite drag-reducing and injection-increasing agent prepared according to the preparation method according to any one of claims 7 to 8 in water injection wells.

10. The use of the high-efficiency composite drag reducing and injection-increasing agent in water injection wells according to claim 9, characterized in that: The application is specifically as follows: the high-efficiency composite drag reducing and injection-increasing agent is configured to a specific concentration and then pumped into a water injection well column.

Images