Film-forming fluid loss additive, method for preparing same, workover fluid, and workover method

Abstract

The application relates to a film-forming fluid loss additive, a preparation method thereof, a workover fluid and a workover method, and relates to the workover field. The film-forming fluid loss additive comprises an oil phase, an emulsifier, acrylamide, N-vinyl pyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride, water and an initiator. The workover fluid comprises water, a viscosity increasing agent, a plugging agent, an acid-soluble temporary plugging agent, an interface modifier, an anti-corrosion agent, a weighting agent and the aforementioned film-forming fluid loss additive. The film-forming fluid loss additive is provided, a polymer obtained through reverse emulsion polymerization of specific acrylamide, N-vinyl pyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyl dimethyl allyl ammonium chloride is massively adsorbed on the surface of a filter cake under the action of high temperature and high pressure to form a high-molecular polymer film with high toughness, and the reduction of the fluid loss is realized. The temperature resistance of the workover fluid is greater than or equal to 180 DEG C, the pressure plugging capacity of the workover fluid to a fractured core is greater than 10 MPa, and the permeability recovery value of the workover fluid is greater than or equal to 92%.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well workover, specifically to a film-forming filtration loss reducing agent and its preparation method, workover fluid, and workover method, and particularly to a high-temperature and high-pressure film-forming filtration loss reducing agent and its preparation method, workover fluid, and workover method. Background Technology

[0002] Gas storage facilities have advantages such as large storage capacity, wide peak-shaving range, and high safety factor, and play an increasingly important role in the development of the natural gas industry.

[0003] Gas storage facilities are typically converted from depleted oil and gas reservoirs. These reservoirs have complex geological conditions, characterized by strong heterogeneity, low reservoir pressure coefficients, and fractured structures. During well workover, the working pressure differential is large, and workover fluid loss frequently occurs. This not only significantly increases the amount of workover fluid used but also easily induces solid phase intrusion damage, fluid sensitivity damage, and aqueous phase trapping damage, affecting production after well workover and seriously impacting the gas storage facility's injection and production efficiency and economic benefits.

[0004] In recent years, hydrocarbon-based workover fluids, gel-type workover fluids, and PRD workover fluid systems have been developed both domestically and internationally.

[0005] For example, CN110305642A discloses a well workover fluid for oil and gas wells, which is composed of brine base fluid, polymer, oil-soluble resin, sodium iminodisuccinate and heat-sensitive additives. The mass content of each component is as follows: polymer 0.5-1%, oil-soluble resin 0.5-1%, sodium iminodisuccinate 0.4-0.8%, heat-sensitive additives 0.1-2%, and brine base fluid as the balance.

[0006] CN104818003A describes a high-temperature, low-pressure oil and gas well protection reservoir workover fluid, belonging to the field of oil and gas well protection fluid technology. It comprises the following components, by mass percentage: NaOH 0.3%, Na2CO3 0.2%, suspension stabilizer 3.5%, film-forming and plugging agent 8.0%, high-temperature fluid loss reducing agent 5.0%, high-temperature hydrogel 1.5%, inorganic hydrogel (HIG-a:HIG-b=1:3) 1.0%, KCl 3%, complexing agent HLH-1 5%, and the balance being fresh water.

[0007] However, existing workover fluids still have shortcomings such as low pressure-bearing and sealing capacity, poor anti-liquid lock effect, and poor self-unblocking ability. They cannot effectively solve the problem of reservoir damage caused by working fluids during gas storage well workover, which brings great challenges to gas storage well workover operations. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a film-forming filtration loss reducing agent and its preparation method, well workover fluid, and well workover method, so as to solve the defects of existing well workover fluids such as low pressure-bearing sealing capacity, insufficient anti-liquid lock effect, and poor self-unblocking ability.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a film-forming filtration loss reducing agent, wherein the raw materials for preparing the film-forming filtration loss reducing agent comprise the following components in parts by weight:

[0011] Oil phase 120-180 parts, emulsifier 15-20 parts, acrylamide 20-30 parts, N-vinylpyrrolidone 8-15 parts, 2-acrylamido-2-methylpropanesulfonic acid 20-40 parts, hexadecyl dimethyl allyl ammonium chloride 5-10 parts, water 90-110 parts, initiator 1.5-2 parts.

[0012] The film-forming filtration loss reducer provided by this invention utilizes a specific combination of acrylamide, N-vinylpyrrolidone, acrylamido-2-methylpropanesulfonic acid, and hexadecyl dimethylallyl ammonium chloride. This results in an agent containing amide groups, quaternary ammonium cations, and sulfonate ions, which are adsorbed onto the filter cake surface through film-forming adsorption. Under high temperature and pressure, a large amount of these adsorbed substances form a tough polymer film on the filter cake surface. Furthermore, the chemical film can bind various particles in the sealing layer together, improving the density of the filter cake and reducing the filtration loss of the workover fluid to the reservoir.

[0013] As a preferred embodiment of the present invention, the oil phase includes white oil and / or diesel oil.

[0014] Preferably, the emulsifier includes one or a combination of at least two of Span-80 emulsifier, Tween 80, or glyceryl monostearate.

[0015] Preferably, the initiator comprises one or a combination of at least two of potassium persulfate, ammonium persulfate, or azobisisobutyronitrile.

[0016] In a second aspect, the present invention provides a method for preparing the film-forming filtration loss reducing agent as described in the first aspect, the method comprising:

[0017] The oil phase and emulsifier are mixed to obtain an oil phase solution;

[0018] Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution.

[0019] An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then, an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

[0020] As a preferred embodiment of the present invention, the endpoint pH value of the pH adjustment is 6.5-8.5.

[0021] As a preferred embodiment of the present invention, the stirring rate of the stirring emulsification is 6000-7000 r / min.

[0022] Preferably, the initiator is added under a protective atmosphere.

[0023] Preferably, the liquid phase temperature at which the initiator is added is 70-80°C.

[0024] Preferably, the polymerization reaction is carried out at a temperature of 70-80°C.

[0025] Preferably, the polymerization reaction takes 3-4 hours.

[0026] Thirdly, the present invention provides a self-degrading chemical film-protected reservoir workover fluid, the self-degrading chemical film-protected reservoir workover fluid comprising:

[0027] Water, thickeners, plugging agents, acid-soluble temporary plugging agents, interface modifiers, corrosion inhibitors, weighting agents, and the aforementioned film-forming and filtration-reducing agents.

[0028] As a preferred embodiment of the present invention, the self-degradable chemical film-protected reservoir workover fluid comprises, by weight:

[0029] 80-120 parts water, 2-10 parts thickener, 2-8 parts sealing agent, 10-40 parts acid-soluble temporary plugging agent, 0.2-1 part interface modifier, 0.5-2 parts corrosion inhibitor, 10-100 parts weighting agent, and 3-12 parts film-forming and filtration loss reducing agent as described in the first aspect.

[0030] As a preferred embodiment of the present invention, the tackifier includes one or a combination of at least two of hydroxyethyl cellulose, high-viscosity polyanionic cellulose HV-PAC, or tackifier CX-216, preferably with a mass ratio of (0.5-2):(1-3) for high-viscosity polyanionic cellulose HV-PAC and tackifier CX-216, and more preferably with a mass ratio of (1-1.1):2 for high-viscosity polyanionic cellulose HV-PAC and tackifier CX-216.

[0031] Preferably, the plugging agent comprises one or a combination of at least two of sulfonated bitumen, polymer microsphere plugging agent, or nano-calcium carbonate, preferably polymer microsphere plugging agent and / or nano-calcium carbonate, and more preferably nano-calcium carbonate.

[0032] Preferably, the acid-soluble temporary plugging agent includes one or a combination of at least two of sepiolite fiber, brucite fiber, or polylactic acid fiber, preferably sepiolite fiber and / or polylactic acid fiber, and more preferably polylactic acid fiber.

[0033] Preferably, the interface modifier includes an organosilicon polymer interface modifier.

[0034] Preferably, the corrosion inhibitor comprises an imidazoline-type corrosion inhibitor.

[0035] Preferably, the weighting agent includes one or a combination of at least two of barite powder, formate, or organic salt weighting agent Weight2, preferably formate and / or organic salt weighting agent Weight2, and more preferably organic salt weighting agent Weight2.

[0036] As a preferred embodiment of the present invention, the self-degradable chemical film-protected reservoir workover fluid comprises, by weight:

[0037] 90-110 parts water, 4-8 parts thickener, 4-8 parts plugging agent, 10-40 parts acid-soluble temporary plugging agent, 0.2-0.5 parts interface modifier, 0.5-1.8 parts corrosion inhibitor, 30-90 parts weighting agent, and 8-11 parts film-forming and filtration loss reducing agent;

[0038] The tackifier is a high-viscosity polyanionic cellulose HV-PAC and a tackifier CX-216 in a mass ratio of (0.5-2):(1-3), the plugging agent is a polymer microsphere plugging agent and / or nano-calcium carbonate, the acid-soluble temporary plugging agent includes sepiolite fiber and / or polylactic acid fiber, and the weighting agent includes formate and / or organic salt weighting agent Weight2.

[0039] Fourthly, the present invention provides a well workover method, the well workover method comprising: performing well workover using a reservoir workover fluid protected by a self-degrading chemical film as described in the third aspect.

[0040] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0041] (1) The well workover fluid provided by the present invention has a temperature resistance of ≥180℃, a pressure-bearing and sealing capacity of ≥8.4MPa for fracture core, a sealing rate of ≥91%, and a permeability recovery value of ≥92%. It overcomes the dual problems of low pressure-bearing and sealing capacity and poor reservoir protection effect. Under the preferred range, the pressure-bearing and sealing capacity of fracture core is >10MPa, the sealing rate is >94%, and the permeability recovery value is >95%.

[0042] (2) The well workover fluid provided by the present invention adopts a preferred scheme by adding polylactic acid fibers of different sizes to the well workover fluid, which can form a stable sealing layer at the opening of the fracture, reduce the entry of harmful solid phases in the working fluid into the reservoir, and unblock it through automatic degradation during the injection and production process (the degradation rate is close to 100% after 28 days), restore the flow capacity of the fracture channel, and improve the gas production volume and gas production efficiency of the gas storage.

[0043] (3) The well workover fluid provided by this invention uses nano-calcium carbonate as a plugging agent, which can enter micro-cracks and micropores to enhance toughness and fill the gaps. The use of organosilicon polymer interface modifiers as waterproofing agents significantly improves the waterproofing and locking capabilities of the workover fluid, reducing damage from water phase trapping. The use of water-soluble organic salt weighting agent Weight2 as a weighting agent overcomes the problems of high solid content and difficult rheological control associated with conventional weighting materials such as barite, limestone powder, and iron ore powder, greatly reducing solid phase intrusion damage. Through the synergistic effect of various treatment agents, the workover fluid and wellbore rock undergo chemical and physical interactions, forming a dense and tough sealing layer on the wellbore, effectively improving the formation's pressure-bearing capacity and preventing harmful solid phases and filtrate in the workover fluid from entering the reservoir. Detailed Implementation

[0044] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0045] This embodiment provides a film-forming filtration loss reducing agent, the raw materials for which the film-forming filtration loss reducing agent is prepared include the following components in parts by weight:

[0046] Oil phase 120-180 parts, emulsifier 15-20 parts, acrylamide 20-30 parts, N-vinylpyrrolidone 8-15 parts, 2-acrylamido-2-methylpropanesulfonic acid 20-40 parts, hexadecyl dimethyl allyl ammonium chloride 5-10 parts, water 90-110 parts, initiator 1.5-2 parts.

[0047] In this invention, the oil phase in the film-forming filtration loss reducing agent is 120-180 parts by weight, for example, it can be 120 parts, 125 parts, 130 parts, 135 parts, 140 parts, 145 parts, 150 parts, 155 parts, 160 parts, 165 parts, 170 parts, 175 parts or 180 parts, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also acceptable.

[0048] In this invention, the emulsifier in the film-forming filtration loss reducing agent is 15-20 parts by weight, for example, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts, etc., but not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0049] In this invention, the acrylamide in the film-forming filtration loss reducing agent is 20-30 parts by weight, for example, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts or 30 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0050] In this invention, the N-vinylpyrrolidone in the film-forming filtration loss reducing agent is 8-15 parts by weight, for example, it can be 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0051] In this invention, the 2-acrylamido-2-methylpropanesulfonic acid in the film-forming filtration loss reducing agent is 20-40 parts by weight, for example, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts or 40 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0052] In this invention, the cetyldimethylallylammonium chloride in the film-forming filtration loss reducing agent is 5-10 parts by weight, for example, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, but not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0053] In this invention, the water in the film-forming filtration loss reducing agent is 90-110 parts by weight, for example, 90 parts, 92 parts, 94 parts, 96 parts, 98 parts, 100 parts, 102 parts, 104 parts, 106 parts, 108 parts or 110 parts, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0054] In this invention, the initiator in the film-forming filtration loss reducing agent is 1.5-2 parts by weight, for example, it can be 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts or 2 parts, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0055] The oil phase includes white oil and / or diesel oil.

[0056] The emulsifier includes one or a combination of at least two of Span-80 emulsifier, Tween 80, or glyceryl monostearate.

[0057] The initiator includes one or a combination of at least two of potassium persulfate, ammonium persulfate, or azobisisobutyronitrile.

[0058] Furthermore, the present invention provides a method for preparing the aforementioned film-forming filtration loss reducing agent, the method comprising:

[0059] The oil phase and emulsifier are mixed to obtain an oil phase solution;

[0060] Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution.

[0061] An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then, an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

[0062] The endpoint pH value for pH adjustment is 6.5-8.5, such as 6.5, 7.0, 7.5, 8 or 8.5, but not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0063] The stirring rate for emulsification is 6000-7000 r / min, for example, it can be 6000 r / min, 6200 r / min, 6400 r / min, 6600 r / min, 6800 r / min or 7000 r / min, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0064] The addition of the initiator is carried out under a protective atmosphere.

[0065] In this invention, the protective atmosphere includes at least one of nitrogen, helium, neon, argon, etc.

[0066] The liquid phase temperature at which the initiator is added is 70-80℃, for example, it can be 70℃, 72℃, 74℃, 76℃, 78℃ or 80℃, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0067] The polymerization reaction temperature is 70-80℃, for example, it can be 70℃, 72℃, 74℃, 76℃, 78℃ or 80℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0068] The polymerization reaction time is 3-4 hours, for example, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours or 4.0 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0069] Furthermore, the present invention provides a self-degrading chemical film-protected reservoir workover fluid, the self-degrading chemical film-protected reservoir workover fluid comprising:

[0070] Water, thickeners, plugging agents, acid-soluble temporary plugging agents, interface modifiers, corrosion inhibitors, weighting agents, and the aforementioned film-forming and filtration-reducing agents.

[0071] The self-degradable chemical film-protected reservoir workover fluid comprises, by weight, the following:

[0072] 80-120 parts water, 2-10 parts thickener, 2-8 parts sealing agent, 10-40 parts acid-soluble temporary plugging agent, 0.2-1 part interface modifier, 0.5-2 parts corrosion inhibitor, 10-100 parts weighting agent, and 3-12 parts of the aforementioned film-forming and filtration loss reducing agent.

[0073] In this invention, the water in the reservoir workover fluid protected by the self-degradable chemical film is 80-120 parts by weight, for example, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, or 120 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0074] In this invention, the viscosity enhancer in the reservoir workover fluid containing the self-degradable chemical film is 2-10 parts by weight, for example, 2, 3, 4, 5, 6, 7, 8, 9 or 10 parts, but not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0075] In this invention, the plugging agent in the reservoir workover fluid containing the self-degradable chemical film is 2-8 parts by weight, for example, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts, but not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0076] In this invention, the acid-soluble temporary plugging agent in the reservoir workover fluid containing the self-degradable chemical film is 10-40 parts by weight, for example, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38 or 40 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0077] In this invention, the interface modifier in the reservoir workover fluid containing the self-degradable chemical film is 0.2-1 parts by weight, for example, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts or 1 part, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0078] In this invention, the corrosion inhibitor in the reservoir workover fluid protected by the self-degradable chemical film is 0.5-2 parts by weight, for example, it can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts or 2 parts, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0079] In this invention, the weighting agent in the reservoir workover fluid containing the self-degradable chemical film is 10-100 parts by weight, for example, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts or 100 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0080] In this invention, the film-forming and filtration loss reducing agent in the self-degradable chemical membrane protection reservoir workover fluid is 3-12 parts by weight, for example, it can be 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts or 12 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0081] The tackifier includes one or a combination of at least two of hydroxyethyl cellulose, high-viscosity polyanionic cellulose HV-PAC, or tackifier CX-216.

[0082] The sealing agent includes one or a combination of at least two of sulfonated asphalt, polymer microsphere sealing agent, or nano-calcium carbonate.

[0083] For example, the sulfonated asphalt used is sulfonated asphalt that conforms to the standard of SY / T 5665-2018 Modified Asphalt for Drilling Fluid Anti-collapse and Sealing Agents, such as FT-1A.

[0084] For example, the polymer microsphere plugging agent used is a microsphere conforming to the Q / SY CPET J120051-2022 standard, such as ISP-1.

[0085] For example, the particle size of the nano-calcium carbonate used is D. 90 <90nm.

[0086] The acid-soluble temporary plugging agent includes one or a combination of at least two of sepiolite fiber, magnesia fiber, or polylactic acid fiber.

[0087] For example, the length of the sepiolite fibers used is 2-5 mm.

[0088] For example, the length of the magnesia fiber used is 2-5 mm.

[0089] For example, the length of the polylactic acid fiber used is ≤5mm, preferably polylactic acid fiber A (3≤A≤5mm), polylactic acid fiber B (1≤B<3mm), and polylactic acid fiber (<1mm) with a mass ratio of (1.8-2.1):(2.8-3.2):(1.8-2.2).

[0090] The interface modifier includes organosilicon polymer interface modifiers.

[0091] For example, the organosilicon polymer interface modifiers used include commonly used organosilicon polymer interface modifiers in the art, such as silane coupling agent KH-560.

[0092] The corrosion inhibitor includes imidazoline-type corrosion inhibitors.

[0093] For example, the imidazoline corrosion inhibitors used include commonly used imidazoline corrosion inhibitors in the art, such as KLSS-A.

[0094] The weighting agent includes one or a combination of at least two of barite powder, formate, or organic salt weighting agent Weight2;

[0095] The self-degradable chemical film-protected reservoir workover fluid comprises, by weight, the following:

[0096] 90-110 parts water, 4-8 parts thickener, 4-8 parts sealing agent, 10-40 parts acid-soluble temporary plugging agent, 0.2-0.5 parts interface modifier, 0.5-1.8 parts corrosion inhibitor, 30-90 parts weighting agent, and 8-11 parts of the aforementioned film-forming and filtration loss reducing agent;

[0097] The tackifier is a high-viscosity polyanionic cellulose HV-PAC and a tackifier CX-216 in a mass ratio of (0.5-2):(1-3), the plugging agent is a polymer microsphere plugging agent and / or nano-calcium carbonate, the acid-soluble temporary plugging agent includes sepiolite fiber and / or polylactic acid fiber, and the weighting agent includes formate and / or organic salt weighting agent Weight2.

[0098] The self-degradable chemical film-protected reservoir workover fluid comprises, by weight, the following:

[0099] 98-100 parts water, 5-6 parts thickener, 6-8 parts plugging agent, 30-36 parts acid-soluble temporary plugging agent, 0.3-0.5 parts interface modifier, 0.6-1.4 parts corrosion inhibitor, 40-60 parts weighting agent, and 8-10 parts of the aforementioned film-forming and filtration loss reducing agent;

[0100] The tackifier comprises high-viscosity polyanionic cellulose HV-PAC and tackifier CX-216 in a mass ratio of (1-1.1):2; the plugging agent is nano-calcium carbonate; the acid-soluble temporary plugging agent is polylactic acid fiber; and the weighting agent is organic salt weighting agent Weight2.

[0101] In this invention, the self-degradable chemical film-protected reservoir workover fluid is obtained by mixing ingredients according to a formula based on weight parts.

[0102] Furthermore, this embodiment provides a well workover method, which includes: performing well workover using the aforementioned self-degrading chemical film-protected reservoir workover fluid.

[0103] Furthermore, to illustrate the advantages of the film-forming filtration loss reducer and self-degrading chemical film protection reservoir workover fluid provided by the present invention, the following practical examples are provided for illustrative purposes:

[0104] Example 1

[0105] This embodiment provides a film-forming filtration loss reducing agent, as detailed below:

[0106] The raw materials for preparing the film-forming filtration loss reducing agent include the following components in parts by weight:

[0107] 150 parts oil phase, 17 parts emulsifier, 24 parts acrylamide, 11 parts N-vinylpyrrolidone, 30 parts 2-acrylamido-2-methylpropanesulfonic acid, 7 parts hexadecyl dimethyl allyl ammonium chloride, 100 parts water, and 1.7 parts initiator.

[0108] The oil phase is white oil; the emulsifier is Span-80 emulsifier; the initiator is potassium persulfate;

[0109] The preparation process of the film-forming filtration loss reducing agent is as follows:

[0110] The oil phase and emulsifier are mixed to obtain an oil phase solution;

[0111] Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution.

[0112] An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

[0113] The final pH value for the pH adjustment is 7.

[0114] The stirring rate for the emulsification process is 6000 r / min; the initiator is added under a protective atmosphere; the liquid phase temperature of the initiator is 75°C; the polymerization temperature is 75°C; and the polymerization time is 3.5 h.

[0115] Example 2

[0116] This embodiment provides a film-forming filtration loss reducing agent, as detailed below:

[0117] The raw materials for preparing the film-forming filtration loss reducing agent include the following components in parts by weight:

[0118] 155 parts oil phase, 17.5 parts emulsifier, 25 parts acrylamide, 12 parts N-vinylpyrrolidone, 32 parts 2-acrylamido-2-methylpropanesulfonic acid, 7.5 parts hexadecyl dimethyl allyl ammonium chloride, 100 parts water, and 1.7 parts initiator.

[0119] The oil phase is white oil; the emulsifier is Tween 80 emulsifier; the initiator is ammonium persulfate;

[0120] The preparation process of the film-forming filtration loss reducing agent is as follows:

[0121] The oil phase and emulsifier are mixed to obtain an oil phase solution;

[0122] Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution.

[0123] An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

[0124] The final pH value for the pH adjustment is 7.

[0125] The stirring rate for emulsification is 6500 r / min; the initiator is added under a protective atmosphere; the liquid phase temperature of the initiator is 76°C; the polymerization temperature is 76°C; and the polymerization time is 3.6 h.

[0126] Example 3

[0127] This embodiment provides a film-forming filtration loss reducing agent, as detailed below:

[0128] The raw materials for preparing the film-forming filtration loss reducing agent include the following components in parts by weight:

[0129] 140 parts oil phase, 16 parts emulsifier, 22 parts acrylamide, 10 parts N-vinylpyrrolidone, 25 parts 2-acrylamido-2-methylpropanesulfonic acid, 8 parts hexadecyl dimethyl allyl ammonium chloride, 98 parts water, and 1.6 parts initiator.

[0130] The oil phase is white oil; the emulsifier is glyceryl monostearate; the initiator is azobisisobutyronitrile (AIBN).

[0131] The preparation process of the film-forming filtration loss reducing agent is as follows:

[0132] The oil phase and emulsifier are mixed to obtain an oil phase solution;

[0133] Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution.

[0134] An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

[0135] The final pH value for the pH adjustment is 8.5;

[0136] The stirring rate for the emulsification process is 6500 r / min; the initiator is added under a protective atmosphere; the liquid phase temperature of the initiator is 72°C; the polymerization temperature is 72°C; and the polymerization time is 3.8 h.

[0137] Example 4

[0138] This embodiment provides a film-forming filtration loss reducing agent, as detailed below:

[0139] The raw materials for preparing the film-forming filtration loss reducing agent include the following components in parts by weight:

[0140] 160 parts oil phase, 18 parts emulsifier, 27 parts acrylamide, 13 parts N-vinylpyrrolidone, 35 parts 2-acrylamido-2-methylpropanesulfonic acid, 6 parts hexadecyl dimethyl allyl ammonium chloride, 105 parts water, and 1.8 parts initiator.

[0141] The oil phase is white oil; the emulsifier is Span-80 emulsifier; the initiator is potassium persulfate;

[0142] The preparation process of the film-forming filtration loss reducing agent is as follows:

[0143] The oil phase and emulsifier are mixed to obtain an oil phase solution;

[0144] Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution.

[0145] An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

[0146] The endpoint pH value for the pH adjustment is 7.5;

[0147] The stirring rate for the emulsification process is 6800 r / min; the initiator is added under a protective atmosphere; the liquid phase temperature of the initiator is 78°C; the polymerization temperature is 78°C; and the polymerization time is 3.2 h.

[0148] Example 5

[0149] This embodiment provides a film-forming filtration loss reducing agent, as detailed below:

[0150] The raw materials for preparing the film-forming filtration loss reducing agent include the following components in parts by weight:

[0151] 180 parts oil phase, 15 parts emulsifier, 30 parts acrylamide, 8 parts N-vinylpyrrolidone, 40 parts 2-acrylamido-2-methylpropanesulfonic acid, 10 parts hexadecyl dimethyl allyl ammonium chloride, 90 parts water, and 1.5 parts initiator.

[0152] The oil phase is white oil; the emulsifier is Span-80 emulsifier; the initiator is potassium persulfate;

[0153] The preparation process of the film-forming filtration loss reducing agent is as follows:

[0154] The oil phase and emulsifier are mixed to obtain an oil phase solution;

[0155] Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution.

[0156] An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

[0157] The final pH value for the pH adjustment is 8.0;

[0158] The stirring rate for the emulsification process is 7000 r / min; the initiator is added under a protective atmosphere (nitrogen); the liquid phase temperature of the initiator is 80°C; the polymerization temperature is 80°C; and the polymerization time is 3 h.

[0159] Example 6

[0160] This embodiment provides a film-forming filtration loss reducing agent, as detailed below:

[0161] The raw materials for preparing the film-forming filtration loss reducing agent include the following components in parts by weight:

[0162] 120 parts oil phase, 20 parts emulsifier, 20 parts acrylamide, 15 parts N-vinylpyrrolidone, 20 parts 2-acrylamido-2-methylpropanesulfonic acid, 5 parts hexadecyl dimethyl allyl ammonium chloride, 110 parts water, and 2 parts initiator.

[0163] The oil phase is white oil; the emulsifier includes glyceryl monostearate; the initiator is potassium persulfate.

[0164] The preparation process of the film-forming filtration loss reducing agent is as follows:

[0165] The oil phase and emulsifier are mixed to obtain an oil phase solution;

[0166] Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution.

[0167] An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

[0168] The final pH value for the pH adjustment is 6.5;

[0169] The stirring rate for the emulsification process is 6000 r / min; the initiator is added under a protective atmosphere (argon); the liquid phase temperature of the initiator is 70°C; the polymerization temperature is 70°C; and the polymerization time is 4 h.

[0170] Example 7

[0171] The only difference from Example 1 is that hexadecyl dimethyl allyl ammonium chloride is replaced with an equal amount of dimethyl diallyl ammonium chloride.

[0172] Example 8

[0173] The only difference from Example 1 is that the acrylamide in the film-forming filtration loss reducing agent is 50 parts by weight.

[0174] Example 9

[0175] The only difference from Example 1 is that N-vinylpyrrolidone is replaced with an equal amount of propenylpyrrolidone.

[0176] The film-forming filtration loss reducing agents obtained in Examples 1-9 were added to the base slurry (by mass percentage: 2% bentonite, 3.0% high-viscosity anionic cellulose HV-PA, with the density controlled at 1.60 g / cm³ using organic salt weighting agent Weight2). 3 The rheological properties of the slurry were tested in a solution containing water as the solvent. The mass of the film-forming and filtration-reducing agent was 3% of the weight of the base slurry. The rheological properties were determined according to the method specified in the national standard GB / T16783.1-2014. The effects of Examples 1-9 on the rheological properties of the base slurry are shown in Table 1.

[0177] Table 1

[0178]

[0179] Application Example 1

[0180] The film-forming filtration loss reducer obtained in Example 1 was used as a component of the self-degrading chemical film protection reservoir workover fluid, as detailed below:

[0181] By weight, 100 parts water, 5 parts thickener (high-viscosity anionic cellulose HV-PAC and thickener CX-216 in a mass ratio of 1:2), 10 parts film-forming filtration loss reducer, and 6 parts blocking agent (nano-calcium carbonate, D) are added. 90 30 parts of an acid-soluble temporary plugging agent (polylactic acid fiber A (3≤A≤5mm), polylactic acid fiber B (1≤B<3mm), polylactic acid fiber (<1mm) in a mass ratio of 2:3:2), 0.3 parts of an interface modifier (KH-560), 0.6 parts of an imidazoline-type corrosion inhibitor (KLSS-A), and 60 parts of a weighting agent (organic salt weighting agent Weight2) were mixed in a stirrer and stirred at room temperature (25℃) for 1 hour to prepare a solution with a density of 1.58 g / cm³. 3 Self-degradable chemical film protects reservoir workover fluid.

[0182] Application Example 2

[0183] The film-forming filtration loss reducer obtained in Example 2 was used as a component of the self-degrading chemical film protection reservoir workover fluid, as detailed below:

[0184] By weight, 100 parts water, 6 parts thickener (high-viscosity anionic cellulose HV-PAC and thickener CX-216 in a mass ratio of 1.1:2), 8 parts film-forming filtration loss reducer, and 8 parts blocking agent (nano-calcium carbonate D) are added. 90=70nm), 36 parts of acid-soluble temporary plugging agent (polylactic acid fiber A (3≤A≤5mm), polylactic acid fiber B (1≤B<3mm), polylactic acid fiber (<1mm) in a mass ratio of 1.8:3.2:1.8), 0.5 parts of interface modifier (silane coupling agent KH-560), 1.4 parts of corrosion inhibitor (imidazoline type corrosion inhibitor KLSS-A), and 40 parts of weighting agent (organic salt weighting agent Weight2) were mixed in a stirrer and stirred at room temperature (25℃) for 1 hour to prepare a solution with a density of 1.39g / cm³. 3 Self-degradable chemical film protects reservoir workover fluid.

[0185] Application Example 3

[0186] The film-forming filtration loss reducer obtained in Example 3 was used as a component of the self-degrading chemical film protection reservoir workover fluid, as detailed below:

[0187] By weight, 80 parts water, 6 parts thickener (high-viscosity anionic cellulose HV-PAC and thickener CX-216 in a mass ratio of 0.5:3), 3 parts film-forming filtration loss reducer, 8 parts plugging agent (polymer microsphere plugging agent IPS-1), 28 parts acid-soluble temporary plugging agent (sepiolite fiber, 2-5 mm in length), 0.6 parts interface modifier (silane coupling agent KH-560), 1.0 part corrosion inhibitor (imidazoline corrosion inhibitor KLSS-A), and 20 parts weighting agent (potassium formate) were mixed in a stirrer and stirred at room temperature (25°C) for 1 hour to prepare a solution with a density of 1.26 g / cm³. 3 Self-degradable chemical film protects reservoir workover fluid.

[0188] Application Example 4

[0189] The film-forming filtration loss reducer obtained in Example 4 was used as a component of the self-degrading chemical film protection reservoir workover fluid, as detailed below:

[0190] By weight, 120 parts water, 4 parts thickener (high-viscosity anionic cellulose HV-PAC and thickener CX-216 in a 2:1 mass ratio), 10 parts film-forming filtration loss reducer, 2 parts plugging agent (polymer microsphere plugging agent ISP-1), 16 parts acid-soluble temporary plugging agent (sepiolite fiber, 2-5 mm in length), 0.3 parts interface modifier (silane coupling agent KH-560), 0.9 parts corrosion inhibitor (imidazoline corrosion inhibitor KLSS-A), and 90 parts weighting agent (sodium formate) were mixed in a stirrer and stirred at room temperature (25°C) for 1 hour to prepare a solution with a density of 2.09 g / cm³. 3 Self-degradable chemical film protects reservoir workover fluid.

[0191] Application Example 5

[0192] The film-forming filtration loss reducer obtained in Example 5 was used as a component of the self-degrading chemical film protection reservoir workover fluid, as detailed below:

[0193] By weight, 80 parts water, 5 parts tackifier (hydroxyethyl cellulose), 4 parts film-forming filtration loss reducer, 7 parts sealing agent (sulfonated asphalt FT-1A), 40 parts acid-soluble temporary plugging agent (brucite fiber, 2-5 mm in length), 1.0 part interface modifier (silane coupling agent KH-560), 0.9 parts corrosion inhibitor (imidazoline corrosion inhibitor KLSS-A), and 100 parts weighting agent (barite powder) were mixed in a mixer and stirred at room temperature (25°C) for 1 hour to prepare a solution with a density of 2.56 g / cm³. 3 Self-degradable chemical film protects reservoir workover fluid.

[0194] Application Example 6

[0195] The film-forming filtration loss reducer obtained in Example 6 was used as a component of the self-degrading chemical film protection reservoir workover fluid, as detailed below:

[0196] By weight, 110 parts water, 3 parts tackifier (hydroxyethyl cellulose), 5 parts film-forming filtration loss reducer, 4 parts sealing agent (sulfonated asphalt FT-1A), 18 parts acid-soluble temporary plugging agent (brucite fiber, 2-5 mm in length), 0.7 parts interface modifier (silane coupling agent KH-560), 0.8 parts corrosion inhibitor (imidazoline corrosion inhibitor KLSS-A), and 10 parts weighting agent (barite powder) were mixed in a mixer and stirred at room temperature (25°C) for 1 hour to prepare a solution with a density of 1.03 g / cm³. 3 Self-degradable chemical film protects reservoir workover fluid.

[0197] Application Example 7

[0198] The only difference from Application Example 1 is that the film-forming filtration loss reducer obtained in Example 7 is used as a component of the self-degrading chemical membrane protection reservoir workover fluid.

[0199] Application Example 8

[0200] The only difference from Application Example 1 is that the film-forming filtration loss reducer obtained in Example 8 is used as a component of the self-degrading chemical membrane protection reservoir workover fluid.

[0201] Application Example 9

[0202] The only difference from Application Example 1 is that the film-forming filtration loss reducer obtained in Example 9 is used as a component of the self-degrading chemical membrane protection reservoir workover fluid.

[0203] The self-degradable chemical film obtained from the application example was subjected to the following performance tests on the reservoir workover fluid:

[0204] 1. Rheological property testing

[0205] The rheological properties of reservoir workover fluids protected by self-degradable chemical films were determined according to the method specified in national standard GB / T 16783.1-2014. The rheological properties of each test object are shown in Table 2.

[0206] Table 2

[0207]

[0208] Table 2 shows that the self-degradable chemical film protection reservoir workover fluids provided in Examples 1-6 exhibited good rheological properties before and after hot rolling at 180℃ for 16 hours, with low API filtration loss (<5mL), low HTHP filtration loss (<15mL), and a density range of 1.00-2.60 g / cm³. 3 It is internally adjustable and can meet the well repair needs under complex geological conditions.

[0209] 2. Pressure-bearing sealing capacity test

[0210] The pressure-bearing sealing capacity was determined according to the methods specified in the industry standard SY / T 5840-2007 "Indoor Test Method for Bridging and Plugging Materials for Drilling Fluids". A high-temperature, high-pressure dynamic plugging simulation experiment was conducted using a self-degradable chemical membrane to protect the reservoir workover fluid. Forward plugging experiments were performed on test modules with crack widths of 1mm, 2mm, and 4mm, and the final pressure displayed was the pressure-bearing sealing capacity. The test results of the maximum pressure-bearing sealing capacity for each embodiment are shown in Table 3.

[0211] Table 3

[0212]

[0213] As shown in Table 3, the self-degradable chemical membrane protection reservoir workover fluids provided in Application Examples 1-6 can form a tight sealing layer in simulated lost circulation zones with 1mm, 2mm, and 4mm fractured plates. The maximum pressure-bearing sealing pressure can reach over 10MPa, with Application Example 1 showing the highest pressure-bearing sealing capacity, reaching 16.8MPa. This indicates that the self-degradable chemical membrane protection reservoir workover fluid has a high pressure-bearing sealing capacity and is expected to solve the technical problem of low pressure-bearing capacity of traditional workover fluids.

[0214] 3. Indoor assessment of reservoir damage

[0215] In 180 o Under high temperature and 3.5 MPa pressure, in accordance with the industry standard SY / T 6540-2021 "Indoor Evaluation Method for Damage to Oil Reservoir by Drilling Fluid and Completion Fluid", the above-mentioned workover fluid was subjected to an indoor evaluation experiment on reservoir damage in a JHDS-2 type high temperature and high pressure dynamic filtration analyzer. The experimental results are shown in Table 4.

[0216] Table 4

[0217]

[0218] As shown in Table 4, the self-degradable chemical membrane-protected reservoir workover fluid provided by this invention achieved a plugging rate of ≥91% for medium-to-high permeability core samples, with Application Examples 1 and 2 exhibiting the best plugging efficiency. After contamination by the self-degradable chemical membrane-protected reservoir workover fluid provided by this invention, the permeability recovery value of the core sample was ≥92%, reaching a maximum of 96.2%, indicating that the self-degradable chemical membrane-protected reservoir workover fluid system provided by this invention can achieve a good reservoir protection effect.

[0219] As demonstrated by the above tests, the self-degradable chemical membrane protection reservoir workover fluid provided by this invention has the characteristics of strong high temperature resistance, high pressure-bearing and plugging capacity, and good reservoir protection effect. It can solve the dual problems of low reservoir pressure-bearing capacity and poor reservoir protection effect that restrict the workover operation of gas storage facilities, meet the needs of workover projects under complex geological conditions, and achieve safe and efficient workover operations.

[0220] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0221] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0222] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A film-forming filtration loss reducing agent, characterized in that, The film-forming filtration loss reducing agent comprises the following raw materials by weight: Oil phase 120-180 parts, emulsifier 15-20 parts, acrylamide 20-30 parts, N-vinylpyrrolidone 8-15 parts, 2-acrylamido-2-methylpropanesulfonic acid 20-40 parts, hexadecyl dimethyl allyl ammonium chloride 5-10 parts, water 90-110 parts, initiator 1.5-2 parts.

2. The film-forming filtration loss reducing agent as described in claim 1, characterized in that, The oil phase includes white oil and / or diesel oil.

3. The film-forming filtration loss reducing agent as described in claim 1, characterized in that, The emulsifier includes one or a combination of at least two of Span-80 emulsifier, Tween 80, or glyceryl monostearate.

4. The film-forming filtration loss reducing agent as described in claim 1, characterized in that, The initiator includes one or a combination of at least two of potassium persulfate, ammonium persulfate, or azobisisobutyronitrile.

5. A method for preparing a film-forming filtration loss reducing agent as described in any one of claims 1-4, characterized in that, The preparation method includes: The oil phase and emulsifier are mixed to obtain an oil phase solution; Acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl dimethyl allyl ammonium chloride and water were mixed, and then the pH was adjusted to obtain an aqueous solution. An aqueous solution is added dropwise to an oil phase solution and stirred to emulsify it. Then, an initiator is added to carry out a polymerization reaction to obtain a film-forming filtration loss reducer.

6. The preparation method according to claim 5, characterized in that, The endpoint pH value for the pH adjustment is 6.5-8.

5.

7. The preparation method according to claim 5, characterized in that, The stirring rate for the emulsification process is 6000-7000 r / min.

8. The preparation method according to claim 5, characterized in that, The initiator is added under a protective atmosphere.

9. The preparation method according to claim 5, characterized in that, The liquid phase temperature at which the initiator is added is 70-80℃.

10. The preparation method according to claim 5, characterized in that, The polymerization reaction is carried out at a temperature of 70-80℃.

11. The preparation method according to claim 5, characterized in that, The polymerization reaction takes 3-4 hours.

12. A self-degradable chemical film protection reservoir workover fluid, characterized in that, The self-degradable chemical film-protected reservoir workover fluid includes: Water, thickener, plugging agent, acid-soluble temporary plugging agent, interface modifier, corrosion inhibitor, weighting agent, and film-forming filtration loss reducing agent as described in any one of claims 1-4.

13. The self-degradable chemical film protection reservoir workover fluid as described in claim 12, characterized in that, The self-degradable chemical film-protected reservoir workover fluid comprises, by weight: 80-120 parts water, 2-10 parts thickener, 2-8 parts sealing agent, 10-40 parts acid-soluble temporary plugging agent, 0.2-1 part interface modifier, 0.5-2 parts corrosion inhibitor, 10-100 parts weighting agent, and 3-12 parts film-forming and filtration loss reducing agent.

14. The self-degradable chemical film protection reservoir workover fluid as described in claim 12 or 13, characterized in that, The thickener includes one or a combination of at least two of hydroxyethyl cellulose, high-viscosity polyanionic cellulose HV-PAC, or thickener CX-216.

15. The self-degradable chemical film protection reservoir workover fluid as described in claim 14, characterized in that, The thickener is a high-viscosity polyanionic cellulose HV-PAC and a thickener CX-216 in a mass ratio of (0.5-2):(1-3).

16. The self-degradable chemical film protection reservoir workover fluid as described in claim 15, characterized in that, The thickener is a high-viscosity anionic cellulose HV-PAC and a thickener CX-216 in a mass ratio of (1-1.1):

2.

17. The self-degradable chemical film protection reservoir workover fluid as described in claim 12 or 13, characterized in that, The plugging agent includes one or a combination of at least two of sulfonated bitumen, polymer microsphere plugging agent, or nano-calcium carbonate.

18. The self-degradable chemical film protection reservoir workover fluid as described in claim 17, characterized in that, The plugging agent is a polymer microsphere plugging agent and / or nano calcium carbonate.

19. The self-degradable chemical film protection reservoir workover fluid as described in claim 18, characterized in that, The sealing agent is nano-calcium carbonate.

20. The self-degradable chemical film protection reservoir workover fluid as described in claim 12 or 13, characterized in that, The acid-soluble temporary plugging agent includes one or a combination of at least two of sepiolite fiber, brucite fiber, or polylactic acid fiber.

21. The self-degradable chemical film protection reservoir workover fluid as described in claim 20, characterized in that, The acid-soluble temporary plugging agent is sepiolite fiber and / or polylactic acid fiber.

22. The self-degradable chemical film protection reservoir workover fluid as described in claim 21, characterized in that, The acid-soluble temporary plugging agent is polylactic acid fiber with a length A of 3≤A≤5mm, a length B of 1≤B<3mm, and a length <1mm, in a mass ratio of (1.8-2.1):(2.8-3.2):(1.8-2.2).

23. The self-degradable chemical film protection reservoir workover fluid as described in claim 12 or 13, characterized in that, The interface modifier includes organosilicon polymer interface modifiers.

24. The self-degradable chemical film protection reservoir workover fluid as described in claim 12 or 13, characterized in that, The corrosion inhibitor includes imidazoline-type corrosion inhibitors.

25. The self-degradable chemical film protection reservoir workover fluid as described in claim 12 or 13, characterized in that, The weighting agent includes one or a combination of at least two of barite powder or formate.

26. The self-degradable chemical film protection reservoir workover fluid as described in claim 12 or 13, characterized in that, The self-degradable chemical film-protected reservoir workover fluid comprises, by weight: 90-110 parts water, 4-8 parts thickener, 4-8 parts sealing agent, 10-40 parts acid-soluble temporary plugging agent, 0.2-0.5 parts interface modifier, 0.5-1.8 parts corrosion inhibitor, 30-90 parts weighting agent, and 8-11 parts film-forming and filtration loss reducing agent.

27. A well repair method, characterized in that, The well workover method includes: using a self-degradable chemical film-protected reservoir workover fluid as described in any one of claims 12-26 for well workover.

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