A delayed exothermic chemical plugging remover for oil field oil layers and its preparation method and application

Abstract

The present application discloses a kind of oil field oil layer delayed exothermic chemical unblocking agent and its preparation method, application, relate to the field of oil field development technology, raw material includes component A, component B and catalyst;In the component A, raw material includes 20 31% ammonium chloride and 69 80% water by mass percentage;In the component B, raw material includes 26 40% sodium nitrite, 4 6% solvent oil, 1 2% mixed aromatic hydrocarbons, 1 2% emulsifier, 0.2 1.5% paraffin dispersant, 1 2% mutual solvent, 0.5 1% alkyl sulfonic acid metal salt, 47.8 64% water by mass percentage;The catalyst is potassium dihydrogen phosphate. The application provides chemical unblocking agent not only with excellent wax dissolving and anti-wax effect, but also with the characteristics of controllable reaction time and delayed exothermicity, can be adjusted according to site needs, suitable for different well depths, convenient for on-site construction, and will not pollute the oil layer.

Description

Technical Field

[0001] The present application relates to the field of oilfield development technology, and in particular to an oilfield oil layer delayed exothermic chemical plugging remover and its preparation method and application. Background Art

[0002] During oil and gas field production, low formation or ambient temperatures often pose adverse challenges. These factors, such as wax deposition in the formation and wellbore, and cold damage to the formation from hydraulic fracturing, can lead to wax deposition in the formation surrounding the wellbore, reducing formation permeability, increasing production difficulties, and increasing production costs. Existing technologies primarily utilize chemical reactions to release heat to heat the area near the wellbore, thereby removing blockages and removing wax.

[0003] The chemical thermogenic system currently used is the thermogenic system of nitrite and ammonium chloride, a common chemical reagent that is inexpensive and readily available. It can react under acid catalysis to produce a large amount of heat and gas, so it is widely used on site.

[0004] The chemical reaction equation is as follows:

[0005]

[0006] However, in actual production and construction, the acid catalysts used in the reaction of sodium nitrite and ammonium chloride are mainly hydrochloric acid, oxalic acid, etc., which generally cause a quick reaction. Although it can achieve the desired purpose, the reaction will occur during the construction process, posing a great safety hazard to the construction. In addition, near the formation, due to the relatively high temperature and pressure, wax deposition is generally not too serious. On the contrary, during the process of crude oil flowing from the bottom of the well to the wellhead, its temperature and pressure will drop to varying degrees. When the temperature drops below the wax precipitation point, wax will precipitate from the crude oil, forming wax crystals that adhere to the wall of the oil casing, seriously affecting the normal production of the oil well. Therefore, the too fast reaction speed of the chemical heat generation system will also result in low utilization efficiency of the heat generation agent and low wax dissolution rate. Summary of the Invention

[0007] In order to solve the problems existing in the prior art, the present application provides an oilfield oil layer delayed exothermic chemical plugging remover and its preparation method and application.

[0008] The present application provides a delayed exothermic chemical plugging remover for oil field oil layers, which adopts the following technical solution:

[0009] A delayed exothermic chemical plugging remover for oilfield oil layers, comprising raw materials including component A, component B, and a catalyst; the raw materials in component A include, by mass percentage, 20-31% ammonium chloride and 69-80% water; the raw materials in component B include, by mass percentage, 26-40% sodium nitrite, 4-6% solvent oil, 1-2% mixed aromatic hydrocarbons, 1-2% emulsifier, 0.2-1.5% paraffin dispersant, 1-2% mutual solvent, 0.5-1% alkylsulfonic acid metal salt, and 47.8-64% water; the mass ratio of component A, component B, and catalyst is 1:0.9-1.1:0.03-0.1; and the catalyst is potassium dihydrogen phosphate.

[0010] Preferably, the catalyst further comprises an auxiliary agent; the auxiliary agent is polyferric sulfate.

[0011] Preferably, the mass ratio of potassium dihydrogen phosphate to polyferric sulfate is 1:0.01-0.07.

[0012] Preferably, the polyferric sulfate is prepared from the following raw materials in parts by weight: 27.9-41.9 parts of ferrous sulfate, 70-105 parts of distilled water, 1.66-2.49 parts of concentrated sulfuric acid, and 5.5-8.3 parts of hydrogen peroxide.

[0013] Preferably, the preparation method of the polyferric sulfate comprises the following steps:

[0014] Add distilled water to ferrous sulfate, stir until dissolved, then add concentrated sulfuric acid, stir evenly to obtain a mixed solution, heat the mixed solution to 20-30°C in a water bath, dropwise add hydrogen peroxide, and control the dropping time to be 30-40 minutes; then heat to 50-60°C, carry out hydrolysis polymerization reaction for 3-5 hours, remove from the mixture, and mature at room temperature for 24-30 hours to obtain a liquid product, which is freeze-dried to obtain solid polyferric sulfate.

[0015] Preferably, the mixed aromatic hydrocarbons are composed of benzene, toluene, xylene, trimethylbenzene and ethylbenzene; the mass ratio of benzene, toluene, xylene, trimethylbenzene and ethylbenzene is 3-5:2-3:10-20:2.5-5:2.5-5.

[0016] Preferably, the metal salt of alkyl sulfonate is C10-C20 alkyl sulfonate sodium salt.

[0017] Preferably, the emulsifier is a mixture of one or more of Tween, OP-10 and Span.

[0018] The present application provides a method for preparing a delayed exothermic chemical plugging remover for oil field oil layers, which adopts the following technical solution:

[0019] A method for preparing a delayed exothermic chemical plugging remover for oil field oil layers comprises the following steps:

[0020] 20-31% ammonium chloride and 69-80% water are mixed uniformly according to mass percentage to obtain component A;

[0021] 26-40% sodium nitrite, 4-6% solvent oil, 1-2% mixed aromatic hydrocarbons, 1-2% emulsifier, 0.2-1.5% paraffin dispersant, 1-2% mutual solvent, 0.5-1% alkyl sulfonic acid metal salt, and 47.8-64% water are mixed uniformly by mass to obtain component B;

[0022] preparing a catalyst;

[0023] After mixing component A, component B and catalyst, a chemical blocking agent with delayed heat release is obtained.

[0024] The application of a delayed exothermic chemical plugging remover for oil field oil layers provided in this application adopts the following technical solution:

[0025] The invention discloses an application of a delayed exothermic chemical plugging remover for oil field oil layers, and the application of the chemical plugging remover in clearing wax and removing plugging in oil field oil layers.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. By adopting the above technical solution, the present application uses potassium dihydrogen phosphate as a catalyst for the reaction of sodium nitrite and ammonium chloride. Potassium dihydrogen phosphate can slowly ionize H in water. + To catalyze the reaction between nitrite and ammonium chloride, the ionization equation is as follows:

[0028] H2PO4 - → HPO4 2- + H +

[0029] HPO4 2- →PO4 3- + H + ;

[0030] As the reaction H + The continuous consumption of KH2PO4 continuously ionizes H + , thereby achieving the purpose of delaying heat release; and the reaction speed can be controlled by adjusting the amount of catalyst, so that a violent chemical reaction occurs within a predetermined time range at a predetermined depth of the oil layer, generating a large amount of gas and releasing huge heat, forming local high temperature and high pressure, so that the wax, asphalt, colloid and other organic matter deposited in the area around the wellbore and in the wellbore can be melted, and then sprayed out from the casing return flow, effectively improving the wax dissolving rate of the chemical plugging remover; it can be adjusted according to on-site needs, suitable for different well depths, convenient for on-site construction, and will not pollute the oil layer;

[0031] 2. This application can also use polyferric sulfate as an auxiliary agent for the potassium dihydrogen phosphate catalyst. Polyferric sulfate will react chemically with the phosphate ions ionized from potassium dihydrogen phosphate to form insoluble iron phosphate precipitates, which can promote the ionization process of potassium dihydrogen phosphate in water and accelerate the H + The production of potassium dihydrogen phosphate broadens the temperature range of the reaction; and the generated insoluble iron phosphate precipitate is also a good flocculant, which can effectively remove impurities and suspended matter in the oil field through adsorption, charge neutralization, mutual attraction and coagulation, thereby improving the deblocking effect;

[0032] 3. The present application adopts mixed aromatic hydrocarbons instead of the single aromatic hydrocarbons in the prior art, which has a certain synergistic effect and can effectively improve the wax dissolution rate; the present application also adds alkyl sulfonic acid metal salts, which have a good anti-wax effect and themselves have good dispersibility. When the wax melts, it will disperse the molten wax into fine particles, so that it remains in a dispersed state after cooling and is not easy to aggregate, thereby achieving the purpose of anti-wax. DETAILED DESCRIPTION

[0033] The present application is further described in detail below with reference to the embodiments.

[0034] The chemical reagents used in the preparation examples, embodiments and comparative examples provided by the present invention are all commercially available products, and their brands and manufacturers are as follows:

[0035] Paraffin dispersant, Anqiu Luxing Trading Co., Ltd.

[0036] Mutual solvent; Weifang Youbo Chemicals Co., Ltd.

[0037] Preparation Example 1: To 27.9 g of ferrous sulfate, 75 g of distilled water was added and stirred until dissolved. 1.66 g of concentrated sulfuric acid was added and stirred evenly to obtain a mixed solution. The mixed solution was heated to 20 ° C in a water bath, and 5.5 g of hydrogen peroxide was added dropwise, and the addition time was controlled to 30 min. The mixture was then heated to 50 ° C and subjected to a hydrolysis polymerization reaction for 3 h. After that, the mixture was taken out and aged at room temperature for 24 h to obtain a liquid product. The liquid product was freeze-dried to obtain solid polyferric sulfate.

[0038] Preparation Example 2: To 34.9 g of ferrous sulfate, 88 g of distilled water was added and stirred until dissolved, followed by the addition of 2.08 g of concentrated sulfuric acid and the stirring to obtain a mixed solution. The mixed solution was placed in a water bath and heated to 25 ° C. 7.4 g of hydrogen peroxide was added dropwise, and the addition time was controlled to 35 min. The mixture was then heated to 55 ° C. and subjected to a hydrolysis polymerization reaction for 4 h. After reaction, the mixture was taken out and aged at room temperature for 27 h to obtain a liquid product. The liquid product was freeze-dried to obtain solid polyferric sulfate.

[0039] Preparation Example 3: To 41.9 g of ferrous sulfate, 105 g of distilled water was added and stirred until dissolved, followed by the addition of 2.49 g of concentrated sulfuric acid and the stirring to obtain a mixed solution. The mixed solution was placed in a water bath and heated to 30 ° C. 8.3 g of hydrogen peroxide was added dropwise, and the addition time was controlled to 40 min. The mixture was then heated to 60 ° C. and subjected to a hydrolysis polymerization reaction for 5 h. The mixture was taken out and aged at room temperature for 30 h to obtain a liquid product. The liquid product was freeze-dried to obtain solid polyferric sulfate.

[0040] Example 1: The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in this example is 3:2:10:2.5:2.5; the emulsifier used is Span 80; and the alkyl sulfonic acid metal salt used is sodium dodecylsulfonate.

[0041] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0042] 26% sodium nitrite, 4% solvent oil, 2% mixed aromatic hydrocarbons, 1% emulsifier, 1.5% paraffin dispersant, 1% mutual solvent, 0.5% alkyl sulfonic acid metal salt, and 64% water were mixed uniformly in a mass ratio to obtain component B;

[0043] Prepare the catalyst potassium dihydrogen phosphate;

[0044] S2. After mixing 100g of component A, 90g of component B, and 3g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0045] Example 2: The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in this example is 3:2:10:2.5:2.5; the emulsifier used is Span 80; and the alkyl sulfonic acid metal salt used is sodium dodecyl sulfonate.

[0046] S1. After mixing 26% ammonium chloride and 74% water in a mass ratio, component A is obtained;

[0047] 33% sodium nitrite, 5% solvent oil, 1.5% mixed aromatic hydrocarbons, 1.5% emulsifier, 0.8% paraffin dispersant, 1.5% mutual solvent, 0.8% alkyl sulfonic acid metal salt, and 55.9% water were mixed uniformly according to the mass ratio to obtain component B;

[0048] Prepare the catalyst potassium dihydrogen phosphate;

[0049] S2. After mixing 100g of component A, 90g of component B, and 3g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0050] Example 3: The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in this example is 3:2:10:2.5:2.5; the emulsifier used is Span 80; and the alkyl sulfonic acid metal salt used is sodium dodecyl sulfonate.

[0051] S1. After mixing 31% ammonium chloride and 69% water in a mass ratio, component A is obtained;

[0052] 40% sodium nitrite, 6% solvent oil, 1% mixed aromatic hydrocarbons, 2% emulsifier, 0.2% paraffin dispersant, 2% mutual solvent, 1% alkyl sulfonic acid metal salt, and 47.8% water were mixed uniformly in a mass ratio to obtain component B;

[0053] Prepare the catalyst potassium dihydrogen phosphate;

[0054] S2. After mixing 100g of component A, 90g of component B, and 3g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0055] Example 4: The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in this example is 3:2:10:2.5:2.5; the emulsifier used is Span 80; and the alkyl sulfonic acid metal salt used is sodium dodecyl sulfonate.

[0056] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0057] 26% sodium nitrite, 4% solvent oil, 2% mixed aromatic hydrocarbons, 1% emulsifier, 1.5% paraffin dispersant, 1% mutual solvent, 0.5% alkyl sulfonic acid metal salt, and 64% water were mixed uniformly in a mass ratio to obtain component B;

[0058] Prepare the catalyst potassium dihydrogen phosphate;

[0059] S2. After mixing 100 g of component A, 100 g of component B, and 6.5 g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0060] Example 5: The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in this example is 3:2:10:2.5:2.5; the emulsifier used is Span 80; and the alkyl sulfonic acid metal salt used is sodium dodecyl sulfonate.

[0061] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0062] 26% sodium nitrite, 4% solvent oil, 2% mixed aromatic hydrocarbons, 1% emulsifier, 1.5% paraffin dispersant, 1% mutual solvent, 0.5% alkyl sulfonic acid metal salt, and 64% water were mixed uniformly in a mass ratio to obtain component B;

[0063] Prepare the catalyst potassium dihydrogen phosphate;

[0064] S2. After mixing 100 g of component A, 110 g of component B, and 0.1 g of potassium dihydrogen phosphate, a delayed exothermic chemical blocking agent is obtained.

[0065] Example 6. The difference between Example 6 and Example 1 is that the mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in Example 6 is 4:2.5:15:3.2:3.2.

[0066] Example 7. The difference between Example 7 and Example 1 is that the mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene and ethylbenzene used in Example 7 is 5:3:20:5:5.

[0067] Example 8: The difference between Example 8 and Example 1 is that the alkyl sulfonate metal salt used in Example 8 is sodium hexadecyl sulfonate.

[0068] Example 9: The difference between Example 9 and Example 1 is that the emulsifier used in Example 9 is a mixture of OP-10 and Span 80, and the mass ratio of the two is 1:1.

[0069] Example 10: The difference between Example 10 and Example 1 is that the emulsifier used in Example 10 is Tween 20.

[0070] Example 11: The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in this example is 3:2:10:2.5:2.5; the emulsifier used is Span 80; the alkyl sulfonic acid metal salt used is sodium dodecylsulfonate; and the polyferric sulfate used is from Preparation Example 1.

[0071] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0072] 26% sodium nitrite, 4% solvent oil, 2% mixed aromatic hydrocarbons, 1% emulsifier, 1.5% paraffin dispersant, 1% mutual solvent, 0.5% alkyl sulfonic acid metal salt, and 64% water were mixed uniformly in a mass ratio to obtain component B;

[0073] Potassium dihydrogen phosphate and polyferric sulfate are mixed uniformly in a mass ratio of 1:0.01 to obtain a catalyst;

[0074] S2. After mixing 100 g of component A, 90 g of component B, and 3 g of catalyst, a chemical deblocking agent with delayed exotherm is obtained.

[0075] Example 12. The difference between Example 12 and Example 11 is that the potassium dihydrogen phosphate and polyferric sulfate in Example 12 are mixed in a mass ratio of 1:0.04.

[0076] Example 13. The difference between Example 13 and Example 11 is that the potassium dihydrogen phosphate and polyferric sulfate in Example 13 are mixed in a mass ratio of 1:0.07.

[0077] Example 14. The difference between Example 14 and Example 11 is that the potassium dihydrogen phosphate and polyferric sulfate in Example 14 are mixed in a mass ratio of 1:0.005.

[0078] Example 15. The difference between Example 15 and Example 11 is that the potassium dihydrogen phosphate and polyferric sulfate in Example 15 are mixed in a mass ratio of 1:0.1.

[0079] Example 16. The difference between Example 16 and Example 11 is that the polyferric sulfate in Example 16 comes from Preparation Example 2.

[0080] Example 17. The difference between Example 17 and Example 11 is that the polyferric sulfate in Example 17 comes from Preparation Example 3.

[0081] Comparative Example 1: The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in this comparative example is 3:2:10:2.5:2.5; the emulsifier used is Span 80; and the alkyl sulfonic acid metal salt used is sodium dodecylsulfonate.

[0082] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0083] 26% sodium nitrite, 4% solvent oil, 2% mixed aromatic hydrocarbons, 1% emulsifier, 1.5% paraffin dispersant, 1% mutual solvent, 0.5% alkyl sulfonic acid metal salt, and 64% water were mixed uniformly in a mass ratio to obtain component B;

[0084] Prepare the catalyst potassium dihydrogen phosphate;

[0085] S2. After mixing 100g of component A, 80g of component B, and 1g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0086] Comparative Example 2: The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene, and ethylbenzene used in this comparative example is 3:2:10:2.5:2.5; the emulsifier used is Span 80; and the alkyl sulfonic acid metal salt used is sodium dodecyl sulfonate.

[0087] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0088] 26% sodium nitrite, 4% solvent oil, 2% mixed aromatic hydrocarbons, 1% emulsifier, 1.5% paraffin dispersant, 1% mutual solvent, 0.5% alkyl sulfonic acid metal salt, and 64% water were mixed uniformly in a mass ratio to obtain component B;

[0089] Prepare the catalyst potassium dihydrogen phosphate;

[0090] S2. After mixing 100 g of component A, 80 g of component B, and 14 g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0091] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the catalyst used in Comparative Example 3 is a 30% hydrochloric acid solution.

[0092] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the aromatic hydrocarbon used in Comparative Example 4 is single xylene, that is, the preparation method of the chemical blocking agent of this comparative example is as follows:

[0093] The emulsifier used in this comparative example is Span 80; the alkyl sulfonic acid metal salt used is sodium dodecyl sulfonate;

[0094] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0095] 26% sodium nitrite, 4% solvent oil, 2% xylene, 1% emulsifier, 1.5% paraffin dispersant, 1% mutual solvent, 0.5% alkyl sulfonic acid metal salt, and 64% water were mixed uniformly according to the mass ratio to obtain component B;

[0096] Prepare the catalyst potassium dihydrogen phosphate;

[0097] S2. After mixing 100g of component A, 90g of component B, and 3g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0098] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that no alkyl sulfonic acid metal salt is added in Comparative Example 5. That is, the preparation method of the chemical blocking agent of this comparative example is as follows:

[0099] The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene and ethylbenzene used in this comparative example is 3:2:10:2.5:2.5; the emulsifier used is Span 80;

[0100] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0101] 26% sodium nitrite, 4% solvent oil, 2% mixed aromatic hydrocarbons, 1% emulsifier, 1.5% paraffin dispersant, 1% mutual solvent, and 64.5% water were mixed uniformly according to the mass ratio to obtain component B;

[0102] Prepare the catalyst potassium dihydrogen phosphate;

[0103] S2. After mixing 100g of component A, 90g of component B, and 3g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0104] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that no emulsifier is added in Comparative Example 6. That is, the preparation method of the chemical blocking agent of this comparative example is as follows:

[0105] The mass ratio of the mixed aromatic hydrocarbons benzene, toluene, xylene, trimethylbenzene and ethylbenzene used in this comparative example is 3:2:10:2.5:2.5; the alkyl sulfonic acid metal salt used is sodium dodecyl sulfonate;

[0106] S1. After mixing 20% ​​ammonium chloride and 80% water in a mass ratio, component A is obtained;

[0107] 26% sodium nitrite, 4% solvent oil, 2% mixed aromatic hydrocarbons, 1.5% paraffin dispersant, 1% mutual solvent, 0.5% alkyl sulfonic acid metal salt, and 65% water were mixed uniformly according to the mass ratio to obtain component B;

[0108] Prepare the catalyst potassium dihydrogen phosphate;

[0109] S2. After mixing 100g of component A, 90g of component B, and 3g of potassium dihydrogen phosphate, a chemical blocking agent with delayed exotherm is obtained.

[0110] Application Examples

[0111] The delayed exothermic plugging remover provided in this application can be used for clearing wax and plugging in oil formations in oil fields. The on-site construction process steps are as follows:

[0112] Step 1: Start the pump: pull out all the pipes and accessories from the well, clean and puncture the oil pipes, measure and check the data;

[0113] Step 2: Sand flushing: flush the sand from the sand exploration surface to the cement surface;

[0114] Step 3: Hot wash: lower the pipe pin to the designed position and wash the well with hot water in a positive circulation;

[0115] Step 4: Replace the high-pressure wellhead gate and seal the wellhead;

[0116] Step 5: Connect the 350 cement truck, the truck, the high-pressure tee and the wellhead liquid pipeline, close the oil and casing gates, and test the wellhead pressure at 15MPa to ensure no puncture or leakage;

[0117] Step 6: Liquid extrusion: Prepare a delayed exothermic chemical plugging remover according to the preparation method of Examples 1-16, with component A, component B, and catalyst prepared in tanks A, B, and C, respectively; close the oil pipe gate, open the casing gate, fill the casing with formation water, open the oil pipe gate, and use three cement trucks to squeeze component A, component B, and catalyst simultaneously through the oil pipe at the same displacement (the catalyst can be squeezed in at different times);

[0118] Step 7: Shut in the well, slowly release the pressure, unload the wellhead, wash and flush the sand with a large displacement, let it settle for 2 hours, and the re-exploration sand surface rises less than 2‰ to be qualified;

[0119] Step 8, well completion: complete the well according to the original pump hanging data.

[0120] Performance testing

[0121] Using the testing methods in SYT 6300-2009 "Technical Requirements for Oil Production Cleaners and Wax Preventers", the wax dissolution rate, wax prevention rate, and viscosity reduction rate of the chemical plugging removers obtained in Examples 1-17 and Comparative Examples 1-6 were tested under the same conditions. The results are shown in Table 1.

[0122] The specific test results are as follows:

[0123]

[0124] The test results in Table 1 show that the delayed exothermic chemical plugging remover provided by the present application has a high wax dissolution rate, indicating that the chemical plugging remover provided by the present application has a wax dissolving and clearing effect; the high wax prevention rate indicates that the chemical plugging remover provided by the present application is not conducive to the deposition of wax molecules on it, and effectively plays a wax prevention role; the high viscosity reduction rate indicates that the chemical plugging remover provided by the present application not only has a good heating and dissolving effect on oil well wax, but also has a certain viscosity reduction effect on heavy oil, which can reduce the viscosity of crude oil.

[0125] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A delayed exothermic chemical plugging remover for oil field oil layers, characterized by: The raw materials include component A, component B and a catalyst; the raw materials in component A include 20-31% ammonium chloride and 69-80% water by mass; the raw materials in component B include 26-40% sodium nitrite, 4-6% solvent oil, 1-2% mixed aromatic hydrocarbons, 1-2% emulsifier, 0.2-1.5% paraffin dispersant, 1-2% mutual solvent, 0.5-1% alkyl sulfonic acid metal salt, and 47.8-64% water by mass; the mass ratio of component A, component B and catalyst is 1:0.9-1.1:0.03-0.1; The catalyst is composed of potassium dihydrogen phosphate and an auxiliary agent; the auxiliary agent is polyferric sulfate; The mass ratio of potassium dihydrogen phosphate to polyferric sulfate is 1:0.01-0.07; The mixed aromatic hydrocarbons are composed of benzene, toluene, xylene, trimethylbenzene and ethylbenzene; the mass ratio of benzene, toluene, xylene, trimethylbenzene and ethylbenzene is 3-5:2-3:10-20:2.5-5:2.5-5; The alkyl sulfonic acid metal salt is C10-C20 alkyl sulfonic acid sodium salt.

2. The delayed exothermic chemical plugging remover for oil field oil layers according to claim 1, characterized in that: The polyferric sulfate is prepared from the following raw materials in parts by weight: 27.9-41.9 parts of ferrous sulfate, 70-105 parts of distilled water, 1.66-2.49 parts of concentrated sulfuric acid, and 5.5-8.3 parts of hydrogen peroxide.

3. The delayed exothermic chemical plugging remover for oil field oil layers according to claim 2, characterized in that: The preparation method of the polyferric sulfate comprises the following steps: Add distilled water to ferrous sulfate, stir until dissolved, then add concentrated sulfuric acid, stir evenly to obtain a mixed solution, heat the mixed solution to 20-30°C in a water bath, dropwise add hydrogen peroxide, and control the dropping time to be 30-40 minutes; then heat to 50-60°C, carry out hydrolysis polymerization reaction for 3-5 hours, remove from the mixture, and mature at room temperature for 24-30 hours to obtain a liquid product, which is freeze-dried to obtain solid polyferric sulfate.

4. The delayed exothermic chemical plugging remover for oil field oil layers according to claim 1, characterized in that: The emulsifier is a mixture of one or more of Tween, OP-10 and Span.

5. The method for preparing an oilfield oil layer delayed exothermic chemical plugging remover according to any one of claims 1 to 4, characterized in that: The following steps are involved: 20-31% ammonium chloride and 69-80% water are mixed uniformly according to mass percentage to obtain component A; 26-40% sodium nitrite, 4-6% solvent oil, 1-2% mixed aromatic hydrocarbons, 1-2% emulsifier, 0.2-1.5% paraffin dispersant, 1-2% mutual solvent, 0.5-1% alkyl sulfonic acid metal salt, and 47.8-64% water are mixed uniformly by mass to obtain component B; preparing a catalyst; After mixing component A, component B and catalyst, a chemical blocking agent with delayed heat release is obtained.

6. Use of the delayed exothermic chemical plugging remover for oil field oil layers according to any one of claims 1 to 4, characterized in that: The chemical plugging remover is used in clearing wax and removing plugging in oil fields.

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