Preparation of blocking remover and application of blocking remover in low-permeability oil layer

Abstract

The invention discloses preparation of a blocking remover and application of the blocking remover in a low-permeability oil layer, and belongs to the technical field of oilfield chemistry. The blocking remover comprises the following raw materials in parts by weight: 40-50 parts of an acidic scale dissolving agent, 18-25 parts of an anionic surfactant, 15-20 parts of cationic surfactant modified mesoporous silica, 25-40 parts of a penetrant, 20-32 parts of a suspending agent, 10-20 parts of a stabilizer and 1-3 parts of a corrosion inhibitor. The blocking remover is stable in system, high in comprehensive blocking removal capacity, wide in application range and beneficial to yield increase and injection increase.

Description

Technical Field

[0001] The present application relates to the preparation of a plugging remover and its application in low-permeability oil layers, belonging to the technical field of oilfield chemistry. Background Art

[0002] Because low-permeability oil layers are susceptible to the effects of external fluids, reservoir damage can occur, significantly reducing the oil layer's seepage efficiency and impacting oil well productivity. This can also cause injection pressures in water injection wells to rise, reducing injection capacity and preventing an effective displacement system between oil and water wells. This, in turn, increases the difficulty of developing low-permeability oil fields. Therefore, reducing reservoir damage and implementing effective deblocking and reconstruction measures for oil layers are key to improving the development of low-permeability oil fields and ensuring the long-term, stable development of the oil industry.

[0003] The composition of oil reservoir blockages is complex and diverse, primarily categorized as inorganic, organic, and other. Inorganic substances are the primary component of oilfield blockages. Salts such as calcium carbonate, calcium sulfate, and barium sulfate can precipitate in oilfield pipelines and reservoirs, causing blockages. Organic substances, including heavy components of crude oil such as asphaltenes and colloids, are another important component of oilfield blockages. Furthermore, particles such as silt and clay from the formation are carried by fluids into pipelines and reservoirs. When the flow rate decreases or encounters an obstruction, they settle and form blockages.

[0004] Traditional plugging removers, such as acidic and alkaline agents, have a certain dissolving effect on blockages, but they suffer from limited effectiveness, significant damage to the formation, corrosion to equipment, and the potential for reprecipitation of reaction products. In recent years, newer plugging removers, such as surfactants, have become increasingly common. These agents work by reducing the oil-water interfacial tension, freeing blockages from the formation surface and achieving the desired effect. However, these agents also have drawbacks such as limited targeting and a short shelf life. Summary of the Invention

[0005] In order to solve the above problems, a method for preparing a plugging remover and its application in low permeability oil layers is provided. The system is stable, has strong comprehensive plugging removal ability, is widely applicable, and is conducive to increasing production and injection.

[0006] The present invention adopts the following technical solutions: According to one aspect of the present application, a plugging remover is provided, comprising the following raw materials in parts by weight: 40-50 parts of an acidic scale dissolving agent, 18-25 parts of anionic surfactant, 15-20 parts of cationic surfactant-modified mesoporous silica, 25-40 parts of a penetrant, 20-32 parts of a suspending agent, 10-20 parts of a stabilizer, and 1-3 parts of a corrosion inhibitor.

[0007] Optionally, the acidic scale dissolving agent is selected from one or more of hydrochloric acid, phosphoric acid, citric acid, ethylenediaminetetraacetic acid and aminosulfonic acid.

[0008] Optionally, the anionic surfactant is selected from one or more of fatty alcohol polyoxyethylene ether sulfates, fatty alcohol polyoxyethylene ether carboxylates and fatty acid methyl ester sulfonates.

[0009] Optionally, the preparation method of the cationic surfactant-modified mesoporous silica comprises the following steps: The mesoporous silica is added to a sodium hydroxide solution and soaked for 8-12 hours, washed, and dried to obtain pretreated mesoporous silica; the pretreated mesoporous silica is then mixed with a cationic surfactant, and shaken in a constant temperature water bath at 20-30° C. for 20-30 hours, filtered, washed, and dried to obtain cationic surfactant-modified mesoporous silica.

[0010] Optionally, the cationic surfactant is selected from one or more of cetyltrimethylammonium bromide, dodecyltrimethylammonium chloride and undecylferroceniumtrimethylammonium bromide.

[0011] Optionally, the weight ratio of mesoporous silica to cationic surfactant is 1:(8-12).

[0012] Optionally, the penetrant includes at least one of penetrant JFC, penetrant OT, and penetrant SF; The suspending agent includes at least one of sodium butylnaphthalene sulfonate, sodium lauryl sulfate, and sodium tripolyphosphate; The stabilizer is potassium chloride or ammonium chloride; The corrosion inhibitor is chitosan or hydroxyethyl cellulose.

[0013] According to another aspect of the present application, a method for preparing any of the above-mentioned blocking agents is provided, comprising the following steps: By weight, 18-25 parts of anionic surfactant, 15-20 parts of cationic surfactant-modified mesoporous silica and 25-40 parts of penetrant are mixed evenly, and then 40-50 parts of acidic scale dissolving agent, 20-32 parts of suspending agent, 10-20 parts of stabilizer and 1-3 parts of corrosion inhibitor are added. Stir at room temperature for 1-3 hours to obtain the blocking agent.

[0014] According to another aspect of the present application, there is provided a use of any of the above-mentioned plugging removers in low permeability oil layers.

[0015] Optionally, the above application includes the following steps: Inject the plugging agent into the low permeability oil layer at a rate of 35-40m 3 The construction pressure is 12.5-13.0MPa, the effective period is 20-25d, flowback, and well shut-in.

[0016] In this application, "room temperature" refers to 20-30°C.

[0017] The beneficial effects of this application include but are not limited to: 1. The preparation and application of the plugging remover in low-permeability oil reservoirs of this application utilizes an acidic scale dissolving agent to remove inorganic scale from the wellbore. Mesoporous silica modified with anionic and cationic surfactants and a penetrant rapidly dissolve organic matter such as wax, colloid, and asphalt in the oil well scale, converting its surface from lipophilic to hydrophilic. The added suspending agent stably suspends clay and sand particles in the scale in the solution and carries them out of the wellbore along with the produced fluid. The stabilizer ensures the stability of the physical and chemical properties of the plugging remover during storage and use, preventing stratification or failure. The corrosion inhibitor The addition of the agent can inhibit the corrosion of downhole equipment in the acidic environment and extend its service life; the various components work synergistically, have a strong comprehensive unblocking ability, and have good reservoir adaptability; it can not only remove organic pollutants such as polymer flocculants, but also dissolve inorganic pollutants such as mud, clay, minerals, carbonate precipitation, and aluminosilicate precipitation. Moreover, since the unblocking agent has a certain oxidizing effect, when removing organic-inorganic composite scale, it can produce iron oxidation products on the pipeline surface, passivating the surface, effectively preventing further contact between the unblocking agent and the pipeline, and slowing down the corrosion rate.

[0018] 2. The preparation of the blockage remover of the present application and its application in low permeability oil layers, the cationic surfactant modified mesoporous silica can enter tiny pores and cracks, and react physically or chemically with the blockage, thereby removing the blockage. Among them, mesoporous silica is used as a carrier to load the cationic surfactant. The cationic surfactant occupies the cationic adsorption sites on the surface of the mesoporous silica through electrostatic attraction, fills the inner surface of its pores, and thus occupies the space in the void structure of the mesoporous silica. On the one hand, the cationic surfactant has a slow release effect and prolongs its action time. On the other hand, the mesoporous silica will rub the oil film on the inner wall of the pipe, so its surface is cleaned cleanly and quickly, thereby improving the blockage removal effect. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0020] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. The raw materials or instruments used, if the manufacturers are not specified, are all conventional products that can be purchased commercially.

[0021] The mesoporous silica mentioned below was purchased from Nanjing Jike Biotechnology Co., Ltd.

[0022] Example 1 A method for preparing a blocking agent comprises the following steps: By weight, 18 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 15 parts of cationic surfactant modified mesoporous silica and 25 parts of penetrant JFC were mixed evenly, and then 20 parts of hydrochloric acid, 20 parts of citric acid, 20 parts of sodium lauryl sulfate, 10 parts of ammonium chloride and 1 part of chitosan were added. The mixture was stirred at room temperature (stirring speed was 3000 r / min) for 1 hour to obtain the blocking agent. The preparation method of cationic surfactant-modified mesoporous silica comprises the following steps: Mesoporous silica was added to a sodium hydroxide solution (1 mol / L) and soaked for 8 h, washed, and dried to obtain pretreated mesoporous silica; then the pretreated mesoporous silica and dodecyltrimethylammonium chloride (5 g / L) were dissolved in water with a weight ratio of mesoporous silica to dodecyltrimethylammonium chloride of 1:8, and the mixture was shaken in a constant temperature water bath at 20°C for 20 h, filtered, washed, and dried to obtain cationic surfactant-modified mesoporous silica.

[0023] Example 2 A method for preparing a blocking agent comprises the following steps: By weight, 12 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 10 parts of sodium fatty acid methyl ester sulfonate, 18 parts of cationic surfactant modified mesoporous silica, 18 parts of penetrant JFC and 14 parts of penetrant OT were mixed evenly, and then 15 parts of hydrochloric acid, 15 parts of citric acid, 15 parts of aminosulfonic acid, 26 parts of sodium butylnaphthalene sulfonate, 15 parts of potassium chloride and 2 parts of hydroxyethyl cellulose were added, and stirred at room temperature (stirring speed was 3000 r / min) for 2 hours to obtain the blocking agent; The preparation method of cationic surfactant-modified mesoporous silica comprises the following steps: Mesoporous silica was added to a sodium hydroxide solution (1 mol / L) and soaked for 10 hours, washed, and dried to obtain pretreated mesoporous silica; then the pretreated mesoporous silica and hexadecyltrimethylammonium bromide (5 g / L) were dissolved in water with a weight ratio of mesoporous silica to hexadecyltrimethylammonium bromide being 1:10, and the mixture was shaken in a constant temperature water bath at 25°C for 24 hours, filtered, washed, and dried to obtain cationic surfactant-modified mesoporous silica.

[0024] Example 3 A method for preparing a blocking agent comprises the following steps: By weight, 25 parts of sodium fatty alcohol polyoxyethylene ether carboxylate, 20 parts of cationic surfactant modified mesoporous silica and 40 parts of penetrant SF were mixed evenly, and then 25 parts of phosphoric acid, 25 parts of ethylenediaminetetraacetic acid, 32 parts of sodium tripolyphosphate, 20 parts of ammonium chloride and 3 parts of chitosan were added. The mixture was stirred at room temperature (stirring speed was 3000 r / min) for 3 hours to obtain the blocking agent. The preparation method of cationic surfactant-modified mesoporous silica comprises the following steps: Mesoporous silica was added to a sodium hydroxide solution (1 mol / L) and soaked for 12 hours, washed, and dried to obtain pretreated mesoporous silica; then the pretreated mesoporous silica and undecylferrocenyltrimethylammonium bromide (5 g / L) were dissolved in a mixed solution of water and ethanol (the volume ratio of water to ethanol was 1:0.2), the weight ratio of mesoporous silica to undecylferrocenyltrimethylammonium bromide was 1:12, and the mixture was shaken in a constant temperature water bath at 30°C for 30 hours, filtered, washed, and dried to obtain cationic surfactant-modified mesoporous silica.

[0025] Example 4 The difference from Example 2 is that sodium fatty acid methyl ester sulfonate is replaced by sodium dodecylbenzene sulfonate.

[0026] Example 5 The difference from Example 2 is that the preparation method of cationic surfactant-modified mesoporous silica includes the following steps: Mesoporous silica and hexadecyltrimethylammonium bromide (5 g / L) were dissolved in water at a weight ratio of 1:10, and the mixture was shaken in a constant temperature water bath at 25°C for 24 hours, filtered, washed, and dried to obtain cationic surfactant-modified mesoporous silica.

[0027] Example 6 The difference from Example 2 is that the weight ratio of mesoporous silica to hexadecyltrimethylammonium bromide is 1:5.

[0028] Comparative Example 1 The difference from Example 2 is that the cationic surfactant-modified mesoporous silica is replaced by hexadecyltrimethylammonium bromide, and the preparation method of the cationic surfactant-modified mesoporous silica is not disclosed.

[0029] Comparative Example 2 The difference from Example 2 is that the mesoporous silica is replaced by silicon dioxide.

[0030] Test Example 1 An application of a plugging remover in a low permeability oil layer comprises the following steps: The plugging removers of Examples 1-6 and Comparative Examples 1-2 were injected into the low permeability oil layer at an injection rate of 38 m 3 The construction pressure is 12.7MPa, the effective period is 24d, flowback, well shut-in, and the cumulative injection volume before and after unblocking is measured.

[0031] Taking a well in Shengli Oilfield as an example, the proportions of inorganic matter, organic matter, and particulate matter in the blockage are 77.40%, 16.23%, and 6.37%, respectively, and the dissolution rate is measured.

[0032] Solubility: Take the plugging removers of Examples 1-6 and Comparative Examples 1-2 respectively, mix them evenly with oilfield formation water at a ratio of 1:3, let them stand at room temperature for 2 hours, and observe whether the mixed solution becomes turbid or precipitates.

[0033] Corrosion: The corrosion rate of the plugging removers of Examples 1-6 and Comparative Examples 1-2 on steel sheets was measured by the hanging plate method. The experimental temperature was 90° C. and the reaction time was 7 h.

[0034] The test results are shown in Table 1 below.

[0035] Table 1

[0036] As can be seen from the results in Table 1, the preparation of the plugging remover of the present application and its application in low permeability oil layers are stable, can effectively dissolve blockages, exhibit low corrosiveness, and the corrosion test results meet oil field standards. It has good reservoir adaptability and is conducive to increasing production and injection.

[0037] The foregoing is merely an embodiment of the present application, and the scope of protection of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the technical ideas and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A blocking agent, characterized in that: The invention comprises the following raw materials in parts by weight: 40-50 parts of acidic scale dissolving agent, 18-25 parts of anionic surfactant, 15-20 parts of cationic surfactant modified mesoporous silica, 25-40 parts of penetrant, 20-32 parts of suspending agent, 10-20 parts of stabilizer, and 1-3 parts of corrosion inhibitor; The anionic surfactant is selected from one or more of fatty alcohol polyoxyethylene ether sulfates, fatty alcohol polyoxyethylene ether carboxylates and fatty acid methyl ester sulfonates; The preparation method of the cationic surfactant modified mesoporous silica comprises the following steps: The mesoporous silica is added to a sodium hydroxide solution and soaked for 8-12 hours, washed, and dried to obtain pretreated mesoporous silica; the pretreated mesoporous silica is then mixed with a cationic surfactant, and shaken in a constant temperature water bath at 20-30° C. for 20-30 hours, filtered, washed, and dried to obtain cationic surfactant-modified mesoporous silica.

2. The blocking agent according to claim 1, characterized in that The acidic scale dissolving agent is selected from one or more of hydrochloric acid, phosphoric acid, citric acid, ethylenediaminetetraacetic acid and aminosulfonic acid.

3. The blocking agent according to claim 1, characterized in that The cationic surfactant is selected from one or more of cetyltrimethylammonium bromide, dodecyltrimethylammonium chloride and undecylferrocenyltrimethylammonium bromide.

4. The blocking agent according to claim 1, characterized in that The weight ratio of mesoporous silica to cationic surfactant is 1:(8-12).

5. The blocking agent according to claim 1, characterized in that The penetrant includes at least one of penetrant JFC, penetrant OT, and penetrant SF; The suspending agent includes at least one of sodium butylnaphthalene sulfonate, sodium lauryl sulfate, and sodium tripolyphosphate; The stabilizer is potassium chloride or ammonium chloride; The corrosion inhibitor is chitosan or hydroxyethyl cellulose.

6. The method for preparing the blocking agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: By weight, 18-25 parts of anionic surfactant, 15-20 parts of cationic surfactant-modified mesoporous silica and 25-40 parts of penetrant are mixed evenly, and then 40-50 parts of acidic scale dissolving agent, 20-32 parts of suspending agent, 10-20 parts of stabilizer and 1-3 parts of corrosion inhibitor are added. Stir at room temperature for 1-3 hours to obtain the blocking agent.

7. Use of the blocking agent according to any one of claims 1 to 5 in low permeability oil layers.

8. The use according to claim 7, characterized in that The following steps are involved: Inject the plugging agent into the low permeability oil layer at a rate of 35-40m 3 The construction pressure is 12.5-13.0MPa, the effective period is 20-25d, flowback, and well shut-in.

Images