A temporary plugging and string checking construction method for a water injection well under pressure

Abstract

The present application relates to the oil and gas industry workover operation process and supporting technology field, in particular to a kind of construction method of water injection well temporary plugging and string checking under pressure, under the condition that wellhead is not pressure relief, degradable temporary plugging gel is extruded into water injection formation, after degradable temporary plugging gel is gelled, formation pressure is blocked, string checking work is carried out under normal pressure condition, after re-entering water injection string, under the condition of formation temperature and pressure, degradable temporary plugging gel is automatically degraded and hydrated, so as to re-establish the channel between wellbore and water injection layer. Through the construction method, the problems of high cost and long operation time faced by the current string checking operation of water injection well under pressure are solved.

Description

Technical Field

[0001] This invention relates to the field of well workover technology and supporting technologies in the oil and gas industry, and in particular to a method for temporary plugging and inspection of pressurized water injection wells. Background Technology

[0002] Changqing Oilfield generally adopts the water injection development model, and currently has nearly 20,000 water injection wells. As development continues to deepen, more than 1,000 pressurized water injection wells need to be inspected and repaired every year, resulting in a large demand for operations.

[0003] Live water injection well string inspection operations mainly employ two methods: conventional operations after depressurization and live operations, to ensure the normal conduct of these operations. Conventional operations after depressurization involve large overflows during tubing string setup and setup, resulting in high well control risks. Furthermore, handling the flowback fluid is difficult, and the costs of transporting kill fluid materials, construction, and waste disposal significantly increase the cost of single-well operations in the oilfield. Live operations using tubing string setup and setup rigs involve complex procedures, long average well dwell times, and high costs. Additionally, the number of live operation teams is insufficient to meet the enormous demand for water well string inspection.

[0004] Before gelation, polymer gel materials exhibit good rheological properties and are easy to inject; after gelation, they are deformable and have adjustable plugging strength. Therefore, polymer gels offer unique advantages in plugging operations. Due to their high deformability, polymer gel materials are not limited by leakage channels. After injection, they can crosslink and copolymerize easily flowing polymer or monomer solutions to form non-flowing gels or jelly, which can achieve plugging effects in extremely small channels. This material is liquid before injection, and after injection, under formation conditions, it transforms into a solid gel with a three-dimensional network structure due to crosslinking, exhibiting excellent plugging properties.

[0005] However, most existing gel-based plugging agents are difficult to apply for temporary plugging operations due to problems such as difficulty in breaking down the gel and reservoir contamination, resulting in high difficulty and risk in on-site construction. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a method for temporary plugging and inspection of pressurized water injection wells. This method solves the current problems of high costs and long operation times in pressurized water injection well inspection operations, avoids pressurized inspection operations, improves construction efficiency, and provides technical support for replenishing reservoir energy.

[0007] This invention is achieved by adopting the following technical solution:

[0008] A method for temporary plugging and inspection of pressurized water injection wells includes the following steps:

[0009] Step S1. Calculate the amount of biodegradable temporary plugging gel used, V, based on the injection-production well network, basic reservoir characteristics, and formation pressure parameters; the biodegradable temporary plugging gel has a viscosity of less than 30 mPa·s at room temperature, a gelation time that is controllable from 1 to 24 hours, a reverse pressure resistance of ≥25 MPa, and a degradation time of 5 to 10 days.

[0010] Step S2. Based on the wellbore string conditions, establish a biodegradable temporary plugging gel injection channel;

[0011] Step S3. Before construction, use clean water for a test squeeze. After the test squeeze, inject biodegradable temporary plugging gel and replacement clean water in sequence; shut off the well and wait for it to set.

[0012] Step S4. Determine whether the temporary plugging of all water injection layers is successful. If so, proceed with the water injection well inspection procedure under normal pressure.

[0013] Step S5. Continue the well shut-in reaction. After the gelled biodegradable temporary plugging gel degrades, perform a water test squeeze. If the wellhead pressure recovers to 60%-90% of the water injection pressure before construction, it is determined that the biodegradable temporary plugging gel has degraded sufficiently, and normal injection can proceed.

[0014] In step S1, the method for calculating the amount V of the biodegradable temporary plugging gel used is as follows:

[0015] V = π * R 2 *h*φ+V0

[0016]

[0017]

[0018] Where V is the amount of biodegradable temporary plugging gel used; R is the near-wellbore water injection sweep radius; h is the effective thickness of the water injection layer; φ is the average porosity of the reservoir; V0 is the effective volume of the dominant waterline diffusion zone; r is the wellbore radius; and m and n are the well spacing and row spacing of the injection and production well network.

[0019] The establishment of the biodegradable temporary plugging gel injection channel in step S2 specifically refers to: establishing a channel from the biodegradable temporary plugging gel to the cement truck, the wellbore, and the water injection layer.

[0020] In step S3, when injecting biodegradable temporary plugging gel and displacement water in sequence, a layered and layer-by-layer injection method is adopted. After each layer of biodegradable temporary plugging gel and displacement water is injected, the well is shut off and allowed to solidify.

[0021] The volume of the replacement water is 120% of the volume of the inlet channel.

[0022] In step S3, during the water test squeeze, the injection volume increases in a stepwise manner.

[0023] In step S3, when injecting water to replace the formation fracture pressure, the injection pressure is controlled to not exceed 80% of the formation fracture pressure, and the pressure rise during the entire process does not exceed 5 MPa.

[0024] The method for determining whether the temporary plugging of all water injection layers is successful in step S4 is as follows: shut the well and wait for condensation for 12 hours, and observe the reading of the wellhead pressure gauge; after the condensation is completed, control the opening and depressurization of the wellhead, and observe the wellhead pressure within 6 hours. If the pressure does not rise, it is considered that the temporary plugging of all water injection layers is successful.

[0025] By weight percentage, the biodegradable plugging gel comprises 4-15% main monomer, 0.5-4% functional crosslinking agent, 0.01-0.5% built-in degradation catalyst, 2-10% reinforcing and toughening monomer, and 0.01-0.2% initiator, with the balance being deionized water;

[0026] The general structural formula of the functional crosslinking agent is shown in Formula I:

[0027]

[0028] in:

[0029] R1=H, CH3; R2=CH2CH2, CH2CH2CH2, CH(CH3)CH2, CH2CH2CH2CH2;

[0030]

[0031] X = F, Cl, Br, I.

[0032] The built-in degradation catalyst is one or more of 2-amino-2-methyl-1-propanol, ethylene glycolamine, diisopropylethanolamine, diacetone acrylamide, or cyclohexylpropanediol.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. In this invention, under conditions where the wellhead pressure is not released, a specific biodegradable temporary plugging gel is selected and injected into the water-injection formation. After the gel solidifies, it seals the formation pressure, and the string inspection is carried out under normal pressure. After the water injection string is re-inserted, under formation temperature and pressure conditions, the biodegradable temporary plugging gel automatically degrades and hydrates after 5-10 days, allowing the wellbore and the water-injection formation to re-establish a channel. This construction method solves the problems of large workload for string inspection in pressurized water injection wells, high costs of conventional well control and pressurized operations, and the difficulty in breaking down most existing gel-based plugging agents, which pollute the reservoir and cannot meet the requirements for temporary plugging operations. This method is particularly suitable for pressurized water injection wells and has good application prospects.

[0035] 2. In this invention, the biodegradable temporary plugging gel is suitable for reservoirs with temperatures ranging from 50°C to 90°C, and the formula can be adjusted according to design requirements to improve the effectiveness of the measures and construction efficiency.

[0036] 3. Based on regional formation pressure and injection-production well network conditions, this invention establishes a method for calculating the amount of biodegradable temporary plugging gel used in the injection layer, which accurately determines the amount of biodegradable temporary plugging gel used, thus achieving both temporary plugging effect and reduced construction costs.

[0037] 4. This invention addresses existing water injection tubing by establishing a multi-layer water injection biodegradable temporary plugging gel extrusion process and extrusion parameter range, thereby improving the efficiency of temporary plugging and inspection string construction. Attached Figure Description

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, wherein:

[0039] Figure 1 This is a schematic diagram of the injection-production well pattern and sweep effect in this invention;

[0040] Figure 2 This is a schematic diagram of the bridge-type concentric layered water injection pipe column in this invention;

[0041] Marked in the image:

[0042] 1. Packer, 2. Hydraulic anchor, 3. Bridge-type concentric water distributor A, 4. Bridge-type concentric water distributor B, 5. Bridge-type concentric water distributor C, 6. Ball seat, 7. Reservoir 1, 8. Reservoir 2, 9. Reservoir 3. Detailed Implementation

[0043] Example 1

[0044] As a basic embodiment of the present invention, the present invention includes a method for temporary plugging and inspection of pressurized water injection wells, comprising the following steps:

[0045] Step S1. Calculate the amount V of biodegradable temporary plugging gel used based on the injection-production well network, basic reservoir characteristics, and formation pressure parameters. The biodegradable temporary plugging gel should have a viscosity of less than 30 mPa·s at room temperature, a controllable gelation time of 1-24 hours, a reverse pressure resistance of ≥25 MPa, and a degradation time of 5-10 days. Any gel meeting these parameters is acceptable.

[0046] Step S2. Based on the wellbore string conditions, establish a biodegradable temporary plugging gel injection channel, ensuring that the channel is unobstructed and free of leaks.

[0047] Step S3. Before construction, use clean water for trial extrusion. After the trial extrusion, inject biodegradable temporary plugging gel and replacement clean water in sequence; shut in the well and wait for it to solidify.

[0048] Step S4. Determine whether the temporary plugging of all water injection layers is successful. If so, proceed with the water injection well inspection procedure under normal pressure.

[0049] Step S5. Continue the well shut-in reaction. After the gelled biodegradable temporary plugging gel degrades, perform a water test squeeze. If the wellhead pressure recovers to 60%-90% of the water injection pressure before construction, it is determined that the biodegradable temporary plugging gel has degraded sufficiently, and normal injection can proceed.

[0050] Example 2

[0051] As a preferred embodiment of the present invention, the present invention includes a method for temporary plugging and inspection of pressurized water injection wells, comprising the following steps:

[0052] Step S1. Calculate the amount V of biodegradable temporary plugging gel used based on the injection-production well network, basic reservoir characteristics, and formation pressure parameters. The biodegradable temporary plugging gel has a viscosity of less than 30 mPa·s at room temperature, a controllable gelation time of 1-24 hours, a reverse pressure resistance of ≥25 MPa, and a degradation time of 5-10 days.

[0053] The specific calculation method for the amount V of biodegradable temporary plugging gel used is as follows:

[0054] V = π * R 2 *h*φ+V0

[0055]

[0056]

[0057] Where V is the amount of biodegradable temporary plugging gel used; R is the near-wellbore water injection sweep radius; h is the effective thickness of the water injection layer; φ is the average porosity of the reservoir; V0 is the effective volume of the dominant waterline diffusion zone; r is the wellbore radius; and m and n are the well spacing and row spacing of the injection and production well network.

[0058] Step S2. Based on the wellbore tubing conditions, establish a biodegradable temporary plugging gel injection channel, i.e., establish a channel from the plugging gel to the cement truck to the wellbore and the water injection layer, ensuring the channel is unobstructed and leak-free. When constructing the target layer, adjust the relevant water distributors on the water injection tubing, seal the water injection channels of other layers, ensure the accuracy of the biodegradable temporary plugging gel injection layer, and ensure that the construction process is carried out under normal wellbore pressure.

[0059] Step S3. Before construction, use clean water for trial extrusion. After the trial extrusion, inject biodegradable temporary plugging gel and replacement clean water in sequence; shut in the well and wait for it to solidify.

[0060] Step S4. Determine whether the temporary plugging of all water injection layers is successful. If so, proceed with the water injection well inspection procedure under normal pressure.

[0061] Step S5. Continue the well shut-in reaction. After the gelled biodegradable temporary plugging gel degrades, perform a water test squeeze. If the wellhead pressure recovers to 60%-90% of the water injection pressure before construction, it is determined that the biodegradable temporary plugging gel has degraded sufficiently, and normal injection can proceed.

[0062] Example 3

[0063] As another preferred embodiment of the present invention, the present invention includes a method for temporary plugging and inspection of pressurized water injection wells, comprising the following steps:

[0064] Step S1. Calculate the amount V of biodegradable temporary plugging gel used based on the injection-production well network, basic reservoir characteristics, and formation pressure parameters. The biodegradable temporary plugging gel has a viscosity of less than 30 mPa·s at room temperature, a controllable gelation time of 1-24 hours, a reverse pressure resistance of ≥25 MPa, and a degradation time of 5-10 days.

[0065] Step S2. Based on the wellbore string conditions, establish a biodegradable temporary plugging gel injection channel.

[0066] Step S3. Before construction, perform a test injection with clean water. After the test injection, inject the biodegradable temporary plugging gel and the replacement clean water in sequence. Shut down the well and wait for it to solidify. The injection volume of the replacement clean water is 120% of the inlet channel volume.

[0067] Step S4. Determine whether the temporary plugging of all water injection layers is successful. If so, carry out the water injection well inspection procedure under normal pressure, perform well control work according to the routine well workover operation, replace key tools of the water injection well, clean and purify the well barrel, and run in the new water injection string according to the design.

[0068] Specifically, determining whether the temporary plugging of all water injection layers is successful involves: shutting in the well and waiting for 12 hours for the water to solidify, while observing the reading on the wellhead pressure gauge. After the solidification period, the wellhead is opened and pressure is released in a controlled manner. The wellhead pressure is then observed for 6 hours. If the pressure does not rise, the temporary plugging of the water injection layer is considered successful.

[0069] Step S5. Continue the well shut-in reaction. After the gelled biodegradable temporary plugging gel degrades, perform a water injection test. If the wellhead pressure recovers to 60%-90% of the pre-injection pressure, the biodegradable temporary plugging gel is considered sufficiently degraded, and normal injection can proceed. Otherwise, measures such as injecting emergency degradation fluid, re-perforating, or small-scale acidizing can be taken to re-establish the water injection channel.

[0070] Example 4

[0071] As the preferred embodiment of the present invention, the present invention includes a method for temporary plugging and inspection of pressurized water injection wells, comprising the following steps:

[0072] Step S1. Calculate the amount of biodegradable temporary plugging gel used, V, based on the injection-production well network, basic reservoir characteristics, and formation pressure parameters.

[0073] The biodegradable temporary plugging gel has a viscosity of less than 30 mPa·s at room temperature, a controllable gelation time of 1-24 hours, a reverse pressure resistance of ≥25 MPa, and a degradation time of 5-10 days, making it suitable for reservoirs at temperatures between 50℃ and 90℃. Specifically, by mass percentage, the biodegradable temporary plugging gel may include 4-15% of the main monomer, 0.5-4% of the functional crosslinking agent, 0.01-0.5% of the built-in degradation catalyst, 2-10% of the reinforcing and toughening monomer, and 0.01-0.2% of the initiator, with the balance being deionized water.

[0074] The main monomer may be one or more of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, sodium methylallyl sulfonate, methacryloyloxyethyltrimethylammonium chloride, sodium p-styrenesulfonate, dimethyldiallyl ammonium chloride, itaconic acid, acrylic acid, or maleic anhydride.

[0075] The general structural formula of the functional crosslinking agent is shown in Formula I:

[0076]

[0077] in:

[0078] R1=H, CH3; R2=CH2CH2, CH2CH2CH2, CH(CH3)CH2, CH2CH2CH2CH2;

[0079]

[0080] X = F, Cl, Br, I.

[0081] The built-in degradation catalyst is one or more of 2-amino-2-methyl-1-propanol, ethylene glycolamine, diisopropylethanolamine, diacetone acrylamide, or cyclohexylpropylene glycol. The reinforcing and toughening monomer is one or more of chitosan, n-butyl isocyanate, calcium carbonate, bismaleimide, or butyl acrylate. The initiator is one or more of ammonium persulfate, persulfate, potassium persulfate-sodium thiosulfate, ammonium persulfate-sodium bisulfite, or azobisisobutyramidine hydrochloride.

[0082] The preparation methods of the functional crosslinking agent, the preparation methods of the biodegradable temporary plugging gel, the corresponding properties of the biodegradable temporary plugging gel and their performance testing methods can be specifically referred to the contents recorded in the Chinese patent document with application number 202311381075.4, and will not be repeated in this embodiment.

[0083] Furthermore, since the wellhead pressure of the injection well is the same as the pressure during normal injection, this pressure value generally does not exceed 125% of the regional formation pressure. If it exceeds this pressure, under-injection treatment is required, and it is not suitable for cross-contamination treatment. The dosage V of the biodegradable temporary plugging gel is mainly used to seal near-wellbore high sweep efficiency zones and dominant waterline diffusion zones. Based on the geostress conditions of the Ordos Basin, it is formulated as shown in the attached instructions. Figure 1 The calculation method for the water injection wave zone shown is as follows:

[0084] V = π * R 2 *h*φ+V0

[0085]

[0086]

[0087] Where V represents the total amount of biodegradable temporary plugging gel designed for a specific water injection layer, and m 3 R is the near-wellbore water injection sweep radius, in meters; h is the effective thickness of the injection layer, in meters; φ is the average reservoir porosity; V0 is the effective volume of the dominant waterline diffusion zone, in meters. 3 ; r is the wellbore radius, m; m and n are the well spacing and row spacing of the injection and production well network, m.

[0088] Step S2. Prepare biodegradable temporary plugging gel at the construction site. The biodegradable temporary plugging gel needs to have an adjustable gelation time under formation temperature and pressure conditions. After construction, it can automatically and quickly degrade, causing little or no damage to the reservoir and not affecting subsequent water injection.

[0089] Based on the wellbore tubing, a biodegradable temporary plugging gel injection channel is established, connecting the cement truck to the water injection wellhead test tubing channel, thus establishing a channel between the temporary plugging gel tanker truck, cement truck, wellhead, water injection tubing, and formation.

[0090] Step S3. Before construction, use clean water for trial extrusion. After the trial extrusion, inject biodegradable temporary plugging gel and replacement clean water in sequence; shut in the well and wait for it to solidify.

[0091] Specifically, when injecting biodegradable temporary plugging gel and displacement water, a layered and progressive injection method is adopted. After each layer of biodegradable temporary plugging gel and displacement water is injected, the well is shut in and allowed to solidify. Currently, the main injection methods include: bridge-type concentric injection, digital wavecode injection, and concentric double-tube injection. Generally, two or more layers are injected, establishing a sequence during injection, sealing each layer from top to bottom to ensure formation energy isolation. Refer to the attached instruction manual. Figure 2Taking the bridge-type concentric injection string, which is widely used in oilfields, as an example, it includes a packer 1, a hydraulic anchor 2, a bridge-type concentric water distributor A3, a bridge-type concentric water distributor B4, a bridge-type concentric water distributor C5, and a ball seat 6. During the injection of biodegradable temporary plugging gel, the gel flows from the wellhead to the bottom of the well. First, the water nozzles of the three injection layers are adjusted to the fully closed state using a measuring cable. For injection into reservoir one 7, the water nozzle of bridge-type concentric water distributor A3 is adjusted to the fully open state to complete the gel injection into reservoir one 7. After injection, the water is replaced, the well is shut in, and the gel is allowed to solidify. For injection into reservoir two 8, the water nozzle of bridge-type concentric water distributor B4 is adjusted to the fully open state to inject the biodegradable temporary plugging gel into reservoir two 8. After injection, the water is replaced, the well is shut in, and the gel is allowed to solidify. For injection into reservoir three 9, the water nozzle of bridge-type concentric water distributor C5 is adjusted to the fully open state. After injection, the water is replaced, and the gel is allowed to solidify. After all water injection layers have solidified, subsequent work can proceed. Other water injection tubing can follow a similar layer-by-layer injection process to ensure that all water injection layers are temporarily plugged with gel, establishing energy isolation between the formation and the wellbore.

[0092] The water injection rate for trial extrusion was increased in stages: 100 L / min, 200 L / min, and 500 L / min, with each rate tested for 3 minutes. Based on the trial results, a reasonable water replacement injection rate was selected, controlling the injection pressure to rise steadily or slowly, without sharp increases or decreases, and not exceeding 80% of the formation fracturing pressure. The injection pressure did not exceed 20 MPa, and the pressure increase throughout the process did not exceed 5 MPa. The volume of water replacing the water was 120% of the channel volume from the wellhead to the formation, including the volume of the injection channels for surface pipelines, the wellhead, and the wellbore, ensuring that all the biodegradable temporary plugging gel was injected into the formation.

[0093] Step S4. Determine whether the temporary plugging of all water injection layers is successful. If so, perform the water injection well inspection procedure under normal pressure, including removing the original well string, cleaning the well, replacing water injection string components, running in the new string, testing and adjusting, etc.

[0094] The method for determining whether temporary plugging of all water injection layers is successful is as follows: The well is shut in for 12 hours to allow the gel to solidify, and the wellhead pressure gauge reading is observed. After solidification, the formation pressure transmission is blocked. Upon opening the wellhead, the original wellbore pressure rapidly transitions to atmospheric pressure. The wellhead pressure is observed for 6 hours. If the pressure does not rise or rises only slightly (less than 0.05 MPa), then temporary plugging of all water injection layers is considered successful. The shut-in solidification time is determined by the gelation time of the biodegradable temporary plugging gel at the reservoir temperature; to ensure effectiveness, it can be appropriately extended.

[0095] Step S5. Continue the well shut-in reaction. After the gelled biodegradable temporary plugging gel degrades, perform a water test squeeze and observe the wellhead pressure. If the wellhead pressure recovers to 60%-90% of the water injection pressure before construction, it is determined that the biodegradable temporary plugging gel has degraded sufficiently, and normal injection can proceed.

[0096] In summary, any other corresponding modifications made by those skilled in the art after reading this invention document, without requiring creative mental effort, based on the technical solutions and concepts of this invention, are all within the scope of protection of this invention.

Claims

1. A method for temporary plugging and inspection of pressurized water injection wells, characterized in that: Includes the following steps: Step S1. Calculate the amount V of biodegradable temporary plugging gel used based on the injection-production well network, basic reservoir characteristics, and formation pressure parameters; the biodegradable temporary plugging gel has a viscosity of less than 30 at room temperature. The gelation time is controllable from 1 to 24 hours, the reverse pressure is ≥25MPa, and the degradation time is 5-10 days; Step S2. Based on the wellbore string conditions, establish a biodegradable temporary plugging gel injection channel; Step S3. Before construction, use clean water for a test squeeze. After the test squeeze, inject the biodegradable temporary plugging gel and the replacement clean water in sequence; shut off the well and wait for it to set. Step S4. Determine whether the temporary plugging of all water injection layers is successful. If so, proceed with the water injection well inspection procedure under normal pressure. Step S5. Continue the well shut-in reaction. After the gelled biodegradable temporary plugging gel degrades, perform a water test squeeze. If the wellhead pressure recovers to 60%-90% of the water injection pressure before construction, it is determined that the biodegradable temporary plugging gel has degraded sufficiently, and normal injection can proceed. In step S1, the method for calculating the amount V of the biodegradable temporary plugging gel used is as follows: in, This refers to the amount of biodegradable temporary plugging gel used; The near-wellbore water injection sweep radius; This refers to the effective thickness of the water injection layer; The average porosity of the reservoir; The effective volume of the dominant waterline diffusion zone; Where is the wellbore radius; m and n represent the well spacing and row spacing of the injection and production well network.

2. The construction method for temporary plugging and inspection of pressurized water injection wells according to claim 1, characterized in that: The establishment of the biodegradable temporary plugging gel injection channel in step S2 specifically refers to: establishing a channel from the biodegradable temporary plugging gel to the cement truck, the wellbore, and the water injection layer.

3. The construction method for temporary plugging and inspection of pressurized water injection wells according to claim 1, characterized in that: In step S3, when injecting biodegradable temporary plugging gel and displacement water in sequence, a layered and layer-by-layer injection method is adopted. After each layer of biodegradable temporary plugging gel and displacement water is injected, the well is shut off and allowed to solidify.

4. The construction method for temporary plugging and inspection of pressurized water injection wells according to claim 3, characterized in that: The volume of the replacement water is 120% of the volume of the inlet channel.

5. The construction method for temporary plugging and inspection of pressurized water injection wells according to claim 3, characterized in that: In step S3, during the water test squeeze, the injection volume increases in a stepwise manner.

6. The construction method for temporary plugging and inspection of pressurized water injection wells according to claim 5, characterized in that: During the water injection test, the injection rate increased in a stepwise manner, including 100L / min, 200L / min and 500L / min.

7. The construction method for temporary plugging and inspection of pressurized water injection wells according to claim 4, characterized in that: In step S3, when injecting water to replace the formation fracture pressure, the injection pressure is controlled to not exceed 80% of the formation fracture pressure, and the pressure rise during the entire process does not exceed 5 MPa.

8. The construction method for temporary plugging and inspection of pressurized water injection wells according to claim 1, characterized in that: The method for determining whether the temporary plugging of all water injection layers is successful in step S4 is as follows: shut the well and wait for condensation for 12 hours, and observe the reading of the wellhead pressure gauge; after the condensation is completed, control the opening and depressurization of the wellhead, and observe the wellhead pressure within 6 hours. If the pressure does not rise, it is considered that the temporary plugging of all water injection layers is successful.

9. The construction method for temporary plugging and inspection of pressurized water injection wells according to claim 1, characterized in that: By weight percentage, the biodegradable plugging gel comprises 4-15% main monomer, 0.5-4% functional crosslinking agent, 0.01-0.5% built-in degradation catalyst, 2-10% reinforcing and toughening monomer, and 0.01-0.2% initiator, with the balance being deionized water; The general structural formula of the functional crosslinking agent is shown in Formula I: Equation I in: R1=H, CH3; R2=CH2CH2, CH2CH2CH2, CH(CH3)CH2, CH2CH2CH2CH2; R3= ； X = F, Cl, Br, I.

10. A method for temporary plugging and inspection of pressurized water injection wells according to claim 9, characterized in that: The built-in degradation catalyst is one or more of 2-amino-2-methyl-1-propanol, ethylene glycolamine, diisopropylethanolamine, diacetone acrylamide, or cyclohexylpropanediol.

Images