Balanced pressure well repair method for recovering homogeneous kill fluid

Abstract

The invention belongs to the technical field of petroleum engineering, and particularly provides a balanced pressure well repair method for recovering homogeneous well killing fluid, which comprises the following steps: determining the density and liquid quantity of the homogeneous well killing fluid according to production parameters of a water injection well, and calculating the amount of required base fluid, solvent and solute according to the determined density and liquid quantity of the homogeneous well killing fluid; preparing homogeneous well killing fluid; a high-pressure water injection well killing method is adopted to balance shaft pressure; underground operation is carried out in a shaft pressure balance state; recovering the homogeneous well killing fluid; setting and completing the well; and the homogeneous well killing fluid is recycled and treated. The problems that when an existing balance pressure method is used for well repairing, operation is complex, well killing fluid cannot be efficiently recycled, the recycling rate is low, the cost caused by medicine loss is high, and the well killing fluid is not suitable for string detection operation of a large number of high-pressure water injection wells are solved. The normal-pressure well repair on the ground is carried out under the conditions of no pressure relief, no plugging and no temporary plugging of the stratum, and the homogeneous kill fluid is efficiently recycled after well completion to realize cyclic utilization.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum engineering, and in particular relates to a balanced pressure well repairing method for recovering homogeneous well-killing fluid. Background Art

[0002] In recent years, with the rapid development of the economy, the country's demand for oil and natural gas resources has continued to increase. The mining conditions of oil wells and the technical level of well repair technology have a great impact on the efficiency and productivity of the entire oil project. In addition, technological modernization can effectively increase the oil content and better meet my country's huge oil needs. If the well repair technology in the downhole operation of the oil project is not significantly improved, major problems will occur in the entire oil project, and even affect the progress of the entire oil project. Therefore, it is very important to promote the downhole operation well repair technology of the oil project and promote the improvement of the technology.

[0003] The ultra-low permeability reservoirs in Changqing are mainly developed by water injection. The wellbore technology of water injection wells is complex and the pressure is high. It is difficult to relieve the pressure of water injection wells under normal pressure, which is not only wasteful and pollutes the environment, but also loses formation energy and destroys the balance between injection and production. The equipment for pressure inspection of water injection wells is complex, cumbersome to operate, has a long cycle and high cost. There are safety and quality issues such as the risk of accidental energy release at the wellhead, the inability to control overflow from drilling to the water distributor, and the difficulty of unsealing the packer after plugging. In order to complete the inspection of high-pressure water injection wells without pressure relief and pressure, the existing methods mainly include temporary plugging method and balanced pressure method.

[0004] The temporary plugging method is to inject polymer into the well to temporarily plug the wellbore and formation, and then perform well repair after there is no overflow at the wellhead. The plugging agents used include oil-soluble temporary plugging agents, polymer gel temporary plugging agents, water-soluble temporary plugging agents, and acid-soluble temporary plugging agents. This method has the limitations of complex process and high cost; the presence of solid phase, which is easy to plug the reservoir; the addition of unblocking agents is easy to cause secondary pollution; and it cannot be reused. It cannot meet the maintenance needs of high-pressure water injection wells.

[0005] The balanced pressure method is a method of injecting high-density well-killing fluid into the wellbore to balance the wellbore pressure, so that the wellhead is at normal pressure and the normal pressure well repair operation is realized. In recent years, China has made great progress in well-killing technology, among which many technologies have been improved in well-killing fluid. The types of well-killing fluid are roughly divided into water-based well-killing fluid, oil-based well-killing fluid, and mixed well-killing fluid. When preparing well-killing fluid, the characteristics of the layer environment are simulated through indoor experiments. It is mainly optimized from the aspects of high temperature resistance, corrosion resistance, filtration loss and protection of oil and gas layers. It meets the construction needs while also meeting the conditions of protecting the reservoir and the environment. It is highly targeted and has a high cost. At present, the commonly used well-killing methods are mainly used in drilling, oil testing, oil and gas well repair and other projects. The operation is complicated, there is no efficient recovery method for well-killing fluid recovery, the recovery rate is low, and the cost caused by the loss of drugs is high. It is not suitable for the inspection and stringing operations of a large number of high-pressure water injection wells.

[0006] A Chinese patent document with publication number CN106894774A discloses an underbalanced tubing replacement process method, including the following steps: obtaining parameters by using the air pressure balance method of casing and tubing; obtaining construction parameters; replacing the air pressure in the tubing by liquid and air pressure replacement method; replacing the air pressure in the casing by liquid and air pressure replacement method; underbalanced drilling or drilling down. The underbalanced tubing replacement process method has a long cycle, high cost, and high risk of replacing tubing under pressure, and achieves protection of oil and gas layers. It is safe and environmentally friendly. During the construction process, there is no liquid return and no environmental pollution. The document does not solve the problem that the balanced pressure method is complicated to operate, the well-killing fluid cannot be efficiently recovered, the recovery rate is low, the cost caused by the loss of drugs is high, and it is not suitable for the inspection of a large number of high-pressure water injection wells. Summary of the invention

[0007] The balanced pressure well repair method for recovering homogeneous well killing fluid provided by the present invention aims to overcome the problems of the balanced pressure well repair method in the prior art, such as complex operation, inability to efficiently recover the well killing fluid, low recovery rate, high cost due to drug loss, and unsuitability for inspection operations of a large number of high-pressure water injection wells.

[0008] To this end, the present invention provides a balanced pressure well repairing method for recovering homogeneous well killing fluid, comprising the following steps:

[0009] 1) Determine the density and liquid volume of the homogeneous well-killing fluid according to the production parameters of the water injection well, and calculate the required amounts of base fluid, solvent and solute according to the determined density and liquid volume of the homogeneous well-killing fluid;

[0010] 2) Use the required base fluid, solvent and solute to prepare the homogeneous well-killing fluid;

[0011] 3) Use homogeneous well killing fluid and high-pressure water injection well killing method to balance the wellbore pressure;

[0012] 4) Carry out downhole operations under the wellbore pressure balance state;

[0013] 5) Recovering homogeneous well-killing fluid;

[0014] 6) Sealing and completing the well;

[0015] 7) Recycle and treat homogeneous well-killing fluid.

[0016] Preferably, the required amounts of base liquid, solvent and solute are calculated by combining theoretical calculation with field experiments to produce a table of empirical values ​​for liquid preparation of various drug formulations.

[0017] Preferably, the volume actually configured when configuring the homogeneous well-killing fluid is 1.5 times the total volume of the well-killing fluid required for the wellbore calculated in theory.

[0018] Preferably, in the step 3), the high-pressure water injection well killing method balances the wellbore pressure and uses one of the three processing methods to complete the well killing, specifically:

[0019] 31) When the sealing of the tubing in the water injection well is intact and the backwash channel of the packer is unobstructed, the reverse circulation + positive squeeze injection method is used to complete the well killing;

[0020] 32) When the pipe seal in the water injection well fails or the pipe seal is intact but the backwash channel is blocked, the forward squeeze + reverse squeeze method is used to complete the well killing;

[0021] 33) When the tubing in the wellbore of an injection well falls off, there is no tubing, and the forward squeeze + reverse squeeze method is unsuccessful, the oil and casing synchronous squeeze injection method is used to complete the well killing.

[0022] Preferably, the 31) is specifically as follows: prepare for the inspection string, first check the casing, when the casing is intact, select the density and amount of the well killing fluid; then check the sealing of the tubing, when the sealing of the tubing is intact, use reverse circulation to balance the annulus, then positive squeeze and balance the oil pipe, and the well killing is completed.

[0023] Preferably, the 32) is specifically:

[0024] Prepare for string inspection. First check the casing. When the casing is intact, select the density and amount of the killing fluid. Then check the sealing of the tubing. When the sealing of the tubing fails, use the tubing to squeeze the killing fluid until the tubing pressure is balanced. The killing is completed.

[0025] Prepare for string inspection, first check the casing, if the casing is intact, select the density and amount of killing fluid; then check the sealing of the tubing, if the tubing is intact; then check whether the backwash channel is unobstructed, if the backwash channel is not unobstructed, use tubing squeeze injection to balance the tubing pressure, and the well is killed;

[0026] Preferably, the 33) is specifically:

[0027] Prepare for string inspection, first check the casing, if the casing is intact, select the density and amount of killing fluid; then check the sealing of the tubing, if the tubing sealing fails, the tubing squeezing and injecting killing fluid cannot balance the tubing pressure, if the tubing has fallen off, use oil and casing synchronous squeezing and injecting until the tubing pressure is balanced, and the killing is completed;

[0028] Prepare to inspect the string, first check the casing, when the casing is intact, select the density and amount of the well killing fluid; then check the sealing of the tubing, when the tubing is intact; then check whether the backwash channel is unobstructed, when the backwash channel is not unobstructed, the tubing squeeze injection cannot balance the tubing pressure; when the tubing has fallen off, use oil and casing synchronous squeeze injection to balance the tubing pressure, and the well killing is completed.

[0029] Preferably, when the situations 31) to 33) do not exist, other string detection methods or other well repair methods are used, specifically:

[0030] When preparing for string inspection, first check the casing. When the casing is incomplete; or when the casing is complete, select the density and amount of the well-killing fluid, and then check the sealing of the tubing. When the tubing sealing fails, the tubing pressure cannot be balanced by squeezing the well-killing fluid through the tubing. When the tubing has fallen off, the tubing pressure cannot be balanced by squeezing the tubing and casing simultaneously; or when the tubing pressure cannot be balanced by squeezing the well-killing fluid through the tubing, and the unsealing of the tubing is unsuccessful, other string inspection methods are used.

[0031] When preparing for string inspection, first check the casing. When the casing is incomplete; or when the casing is complete, select the density and amount of the well-killing fluid, and then check the sealing of the tubing. When the tubing is sealed, then check whether the backwash channel is unobstructed. When the backwash channel is not unobstructed, tubing squeezing cannot balance the tubing pressure. When the tubing has fallen off, the simultaneous squeezing of oil and casing cannot balance the tubing pressure; or after the tubing squeezing and injection of well-killing fluid cannot balance the tubing pressure, and the unsealing of the tubing is unsuccessful, other well repair methods are used.

[0032] Preferably, the step 5) recovers the homogeneous well-killing fluid by pulse induced blowback recovery method.

[0033] Preferably, in step 7) the homogeneous well-killing fluid is recycled and treated by purifying the returned well-killing fluid online through a homogeneous fluid treatment device, and using the purified well-killing fluid as a base fluid to adjust its density so that it meets the working requirements of the next well.

[0034] Beneficial effects of the present invention:

[0035] 1. The balanced pressure well repairing method for recovering homogeneous well-killing fluid provided by the present invention comprises the following steps: 1) determining the density and liquid volume of the homogeneous well-killing fluid according to the production parameters of the water injection well, and calculating the required amounts of base fluid, solvent and solute according to the determined density and liquid volume of the homogeneous well-killing fluid; 2) configuring the homogeneous well-killing fluid using the required base fluid, solvent and solute; 3) balancing the wellbore pressure using the homogeneous well-killing fluid and the high-pressure water injection well killing method; 4) carrying out downhole operations under the wellbore pressure balanced state; 5) recovering the homogeneous well-killing fluid; 6) sealing and completing the well; 7) recycling and treating the homogeneous well-killing fluid; the formation pressure can be balanced, and normal pressure well repairing can be carried out on the ground without depressurizing, plugging or temporarily plugging the formation, and the homogeneous well-killing fluid can be efficiently recovered and treated after the well is completed for recycling.

[0036] 2. In the balanced pressure well repairing method for recovering homogeneous well-killing fluid provided by the present invention, the required amounts of base fluid, solvent and solute are calculated by combining theoretical calculation with field experiments, and a table of empirical values ​​for the preparation of various drug formulas is statistically calculated, that is, the required amounts of base fluid, solvent and solute are calculated using the empirical value method. The operation is simpler and more convenient, and the work can be completed by operators on site.

[0037] 3. The balanced pressure well repairing method for recovering homogeneous well-killing fluid provided by the present invention, the high-pressure water injection well killing method balances the wellbore pressure and adopts one of three treatment methods to complete the well killing. When the sealing of the tubing in the water injection well is intact and the backwash channel of the packer is unobstructed, the reverse circulation + forward squeezing method is adopted; when the sealing of the tubing in the water injection well fails or the tubing is intact but the backwash channel is not unobstructed, the forward squeezing + reverse squeezing method is adopted; when the tubing in the wellbore of the water injection well falls off, there is no tubing and the forward squeezing + reverse squeezing method is unsuccessful, the synchronous squeezing method is adopted; it can meet the well repairing needs in various situations and has strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described in detail below with reference to the accompanying drawings.

[0039] Figure 1 is a flow chart of a balanced pressure well repair method for recovering homogeneous well killing fluid;

[0040] Figure 2 An operational flow chart of a high-pressure water injection well killing method;

[0041] Figure 3 This is a schematic diagram of reverse circulation + forward squeeze injection method;

[0042] Figure 4 It is a schematic diagram of the forward extrusion + reverse extrusion method;

[0043] Figure 5 It is a schematic diagram of the synchronous squeeze injection method;

[0044] Figure 6 It is the operation flow chart of underground operation;

[0045] Figure 7 This is a schematic diagram of the pulse induced jet flowback recovery method.

[0046] Explanation of the accompanying reference numerals: 1. oil casing annulus; 2. oil pipe; 3. oil pressure; 4. casing pressure. DETAILED DESCRIPTION

[0047] like Figure 1 As shown, a balanced pressure well repairing method for recovering homogeneous well killing fluid comprises the following steps:

[0048] 1) Determine the density and liquid volume of the homogeneous well-killing fluid according to the production parameters of the water injection well, and calculate the required amounts of base fluid, solvent and solute according to the determined density and liquid volume of the homogeneous well-killing fluid;

[0049] 2) Use the required base fluid, solvent and solute to prepare the homogeneous well-killing fluid;

[0050] 3) Use homogeneous well killing fluid and high-pressure water injection well killing method to balance the wellbore pressure;

[0051] 4) Carry out downhole operations under the wellbore pressure balance state;

[0052] 5) Recovering homogeneous well-killing fluid;

[0053] 6) Sealing and completing the well;

[0054] 7) Recycle and treat homogeneous well-killing fluid.

[0055] The present invention realizes the normal pressure well repairing operation on the ground of the high-pressure water injection well without pressure relief, plugging and temporary plugging of the formation. The operation is zero-emission throughout the whole process, safe and controllable, and the recovery of the well-killing fluid is not limited by the wellbore conditions, and the recovery rate can be as high as more than 90%. The present invention eliminates the hidden safety hazards of high-pressure operation at the wellhead, avoids the energy loss of the formation caused by pressure relief and the safety and environmental protection risks brought about.

[0056] Preferably, the density calculation formula of the homogeneous well-killing fluid in step 1) is:

[0057] ρ 理论 gH1=ρ 实际 g(H1-h) (1)

[0058] In formula (1), h is the buffer height; H1 is the vertical height of the upper edge of the perforation section; ρ 理论 is the theoretical required well-killing fluid density; g is the gravitational acceleration; ρ 实际 It is the actual density required on site for the well killing fluid.

[0059] Preferably, the buffer height is 50 to 100 meters.

[0060] Preferably, the calculation formula of the theoretically required killing fluid density is:

[0061] P 关井 =ρ 理论 gH1 (2)

[0062] In formula (2), P 关井 is the shut-in bottom hole pressure; H1 is the vertical height of the upper edge of the perforation section; ρ 理论 is the theoretical required density of well-killing fluid; g is the gravitational acceleration.

[0063] Preferably, the homogeneous well-killing fluid comprises, per cubic meter: water: 0.485 m 3 ~0.597m 3 , calcium chloride 110.44kg~215.53kg, sodium nitrate 466.02kg~573.13kg, zinc bromide 142~542.7kg, HS-3 imidazoline quaternary ammonium salt (corrosion inhibitor) 100~200kg.

[0064] Preferably, the density of the homogeneous well-killing fluid is in the range of 1.2 g / cm 3 ~1.8g / cm 3 .

[0065] Preferably, the calculation formula of the liquid volume of the homogeneous well-killing fluid in step 1) is:

[0066]

[0067]

[0068]

[0069]

[0070] In formula (3) to formula (6), D1 is the inner diameter of the casing; D2 is the inner diameter of the oil pipe; D3 is the outer diameter of the oil pipe; v 环空 is the annulus volume; v 油管 is the volume of the oil pipe; v 补充 v is the volume to be replenished; 井筒 The volume of wellbore killing fluid required.

[0071] Preferably, the actual volume of the homogeneous well-killing fluid configured is 1.5 times the total volume of the well-killing fluid required by the wellbore calculated in theory, so as to better meet the actual needs.

[0072] Preferably, the calculation formula for the amount of base liquid, z solvent and solute required in step 1) is (taking the formula with the highest density of 1.5g / cm3 as an example for explanation, the calculation method for other formulas is the same):

[0073]

[0074] V 实配压井液体积 =α×V 井筒体积 (8)

[0075]

[0076]

[0077] In formula (7) to formula (10),

[0078] The known data are: D1 is the inner diameter of the annulus m; H is the vertical height of the upper edge of the perforation section m; β is the expansion rate of the well-killing fluid (1.5g / cm 3 The well killing fluid is 1.82, 1.6g / cm 3 The killing fluid is 1.86); α is 1.5 (considering various conditions on site, the actual killing fluid volume is generally 1.5 times the theoretical calculated value); ρ is the base fluid density g / cm 3 ;

[0079] The data that needs to be measured experimentally are: z is the dilution amount m 3 (1m3 Density: 1.5g / cm 3 The volume of clean water used to dilute the well-killing fluid to the base fluid density ρ is recorded as z);

[0080] Based on the known data and experimentally measured data z, according to formula (8), (9), (10), it can be calculated that: X is the required base liquid volume m 3 ; n is the theoretical dilution water consumption m 3 ;

[0081] Calculate the amount of medicine to be added based on the theoretical dilution water consumption:

[0082] m 加药 =n·m 药品 (11)

[0083] In formula (11), m 加药 is the amount of diluted drug to be added, m 药品 is the amount of undiluted drug;

[0084] Specifically: m 硝酸钠 = n·527.47kg, m 氯化钙 =n·243.96kg,m 溴化锌 =n·54.95kg.

[0085] Preferably, the required amounts of base liquid, solvent and solute are calculated by combining theoretical calculation with field experiments to produce a table of empirical values ​​for liquid preparation of various drug formulations.

[0086] Specifically, the combination of theoretical calculation and field experiment adopts the empirical value calculation method of base liquid and solute dosage. This method combines theoretical calculation with field experiment to statistically calculate the empirical value table of liquid preparation for various drug formulas. The optimal formula of three solutes, calcium nitrate, calcium chloride and potassium chloride, is used as an example to illustrate (the calculation method of other formulas is the same). The empirical value table of liquid preparation is shown in Table 1. This table statistically calculates 1m 3 Under solvent conditions, the density and volume values ​​of the drilling fluid when the solute is gradually added according to the formula ratio. The on-site operators can refer to Table 1 to calculate the amount of base fluid and each solute required to adjust the base fluid at a certain density value to the homogeneous drilling fluid density and liquid volume required for the operation.

[0087] Table 1 Liquid preparation experience table

[0088]

[0089] Preferably, Figure 2 As shown, in step 3), the high-pressure water injection well killing method balances the wellbore pressure and uses one of the three processing methods to complete the well killing, specifically:

[0090] like Figure 3 As shown,

[0091] 31) When the sealing of the tubing in the water injection well is intact and the backwash channel of the packer is unobstructed, the reverse circulation + positive squeeze injection method is used to complete the well killing;

[0092] like Figure 4 As shown in FIG32 , when the pipe string seal in the water injection well fails or the pipe string seal is intact but the backwash channel is blocked, the forward squeeze + reverse squeeze method is used to complete the well killing;

[0093] like Figure 5 As shown in FIG. 33 ), when the tubing in the wellbore of a water injection well falls off, there is no tubing, and the forward squeeze + reverse squeeze method is unsuccessful, the oil and casing synchronous squeeze injection method is used to complete the well killing.

[0094] Specifically, Figure 2 In the process, the casing integrity judgment method is: when there is no casing rupture, no verification seal failure history, and no sudden drop in water injection pressure, the casing is judged to be intact;

[0095] The method for judging the sealing performance of the tubing string is as follows: if there is no backflow from the casing annulus 1 and the casing pressure 4 drops to zero, the sealing performance of the tubing string above the casing protection isolation is intact;

[0096] The method for judging whether the backwash channel is unobstructed is: if the backwash channel can circulate normally, then the backwash channel is unobstructed; otherwise, it is blocked;

[0097] The method for judging the wellbore well pressure balance is: when the pressure drops to zero, there is no overflow at the wellhead and the annular liquid level is stable, the wellbore well pressure balance is achieved.

[0098] During the well killing process, the well killing pressure is required to be less than the minimum value among the wellbore internal pressure, the oil layer rupture pressure and the oil pipe pressure level.

[0099] Specifically:

[0100] Preferably, the 31) is specifically as follows: prepare for the inspection string, first check the casing, when the casing is intact, select the density and amount of the well killing fluid; then check the sealing of the tubing, when the sealing of the tubing is intact, use reverse circulation to balance the annulus, then positively squeeze and balance the oil pipe 2, and the well killing is completed.

[0101] Preferably, the 32) is specifically:

[0102] Prepare for string inspection. First check the casing. When the casing is intact, select the density and amount of the killing fluid. Then check the sealing of the tubing. When the sealing of the tubing fails, use the tubing to squeeze the killing fluid until the tubing pressure is balanced. The killing is completed.

[0103] Prepare for string inspection, first check the casing, if the casing is intact, select the density and amount of killing fluid; then check the sealing of the tubing, if the tubing is intact; then check whether the backwash channel is unobstructed, if the backwash channel is not unobstructed, use tubing squeeze injection to balance the tubing pressure, and the well is killed;

[0104] Preferably, the 33) is specifically:

[0105] Prepare for string inspection, first check the casing, if the casing is intact, select the density and amount of killing fluid; then check the sealing of the tubing, if the tubing sealing fails, the tubing squeezing and injecting killing fluid cannot balance the tubing pressure, if the tubing has fallen off, use oil and casing synchronous squeezing and injecting until the tubing pressure is balanced, and the killing is completed;

[0106] Prepare to inspect the string, first check the casing, when the casing is intact, select the density and amount of the well killing fluid; then check the sealing of the tubing, when the tubing is intact; then check whether the backwash channel is unobstructed, when the backwash channel is not unobstructed, the tubing squeeze injection cannot balance the tubing pressure; when the tubing has fallen off, use oil and casing synchronous squeeze injection to balance the tubing pressure, and the well killing is completed.

[0107] Preferably, when the situations 31) to 33) do not exist, other string detection methods or other well repair methods are used, specifically:

[0108] When preparing for string inspection, first check the casing. When the casing is incomplete; or when the casing is complete, select the density and amount of the well-killing fluid, and then check the sealing of the tubing. When the tubing sealing fails, the tubing pressure cannot be balanced by squeezing the well-killing fluid through the tubing. When the tubing has fallen off, the tubing pressure cannot be balanced by squeezing the tubing and casing simultaneously; or when the tubing pressure cannot be balanced by squeezing the well-killing fluid through the tubing, and the unsealing of the tubing is unsuccessful, other string inspection methods are used.

[0109] When preparing for string inspection, first check the casing. When the casing is incomplete; or when the casing is complete, select the density and amount of the well-killing fluid, and then check the sealing of the tubing. When the tubing is sealed, then check whether the backwash channel is unobstructed. When the backwash channel is not unobstructed, tubing squeezing cannot balance the tubing pressure. When the tubing has fallen off, the simultaneous squeezing of oil and casing cannot balance the tubing pressure; or after the tubing squeezing and injection of well-killing fluid cannot balance the tubing pressure, and the unsealing of the tubing is unsuccessful, other well repair methods are used.

[0110] Other string detection methods and other well repair methods are existing methods and will not be introduced in detail here.

[0111] Preferably, the reverse circulation + forward squeeze injection method comprises the following steps:

[0112] 11) Injection of well-killing fluid in the casing annulus through reverse circulation. First, a certain amount of isolation fluid is squeezed into the casing annulus to separate the well-killing fluid from the water in the wellbore, and then the well-killing fluid is injected using the constant displacement method. During the well-killing process, the throttle valve installed at the outlet of the tubing controls the return flow of the tubing so that the injection displacement is consistent with the return displacement, thereby achieving the effect of ensuring the stability of the bottom hole pressure and monitoring the dynamic changes of the well-killing. Under normal circumstances, the pump pressure decreases linearly when the constant displacement injection is used. When the well-killing fluid is injected and the casing pressure is 0MPa after the pump is stopped, it is considered qualified if the pressure does not rise for 10 minutes. If the pump pressure continues to rise during the injection process, the reason is that the backwash channel is not drained in time. At this time, the injection displacement needs to be reduced. If the pressure continues to rise and exceeds the upper limit of the pressure, the operation should be stopped, and the cause should be analyzed and determined before adjusting the well-killing plan; if the pressure drops for a period of time during the injection process and remains unchanged, it may be that the tubing string is broken and leaking. At this time, the pump needs to be stopped, and the cause should be analyzed and determined before adjusting the well-killing plan.

[0113] 12) Tubing squeeze injection: The tubing squeeze injection method is used to balance the tubing pressure. First, squeeze in the isolation fluid to separate the well-killing fluid from the water in the well, and then squeeze in an appropriate amount of well-killing fluid.

[0114] 13) Stop the pump, shut down the diffusion pressure of the well, observe that the oil and casing pressure are 0MPa, and there is no overflow at the wellhead.

[0115] The forward extrusion + reverse extrusion method includes the following steps:

[0116] 21) Tubing squeeze injection to balance tubing pressure. Use tubing squeeze injection to balance tubing pressure. First squeeze in the isolation fluid to separate the well-killing fluid from the water in the well, and then squeeze in the appropriate homogeneous well-killing fluid. Stop the pump, shut down the well diffusion pressure, and observe that the oil pressure 3 is 0MPa, and there is no overflow at the tubing outlet to be qualified.

[0117] 22) The second step is to install the blowout preventer wellhead and unseal the pipe string.

[0118] 23) Balance casing pressure by squeezing oil from the casing annulus. Stop the pump, shut down the well to diffuse the pressure, and observe that the oil and casing pressures are 0 MPa, and there is no overflow at the wellhead.

[0119] The synchronous squeeze injection method includes the following steps:

[0120] The tubing 2 and casing 4 are squeezed and injected synchronously to balance the wellbore pressure;

[0121] 32) Automatically adjust the wellbore balance and monitor the liquid level when the well is shut in.

[0122] Preferably, Figure 6 As shown, the step 4) performs downhole operations in a wellbore pressure balanced state, including the following steps:

[0123] Prepare for string inspection (check the string tool string), kill the well, start drilling the original well, and install the blowout preventer at the wellhead;

[0124] When the well is drilled to the bottom of the well, the completion drill is lowered, the killing fluid is recovered, and the well is completed;

[0125] When the well cannot reach the bottom of the well, lower the treatment wellbore drill, recover the well killing fluid, treat the wellbore to complete the well killing, raise the treatment wellbore drill, lower the completion drill, recover the well killing fluid, and complete the well;

[0126] When the well cannot reach the bottom of the well, the treatment wellbore drill is lowered to recover the well-killing fluid. If the treatment wellbore has not completed well killing, the treatment wellbore drill is raised and the treatment wellbore drill is lowered again to recover the well-killing fluid until the treatment wellbore completes well killing.

[0127] The main requirements of the operation process are: ① During the drilling process, the well-killing fluid must be continuously replenished, and the replenishment volume is 1.5 times the volume of the pulled-out pipe string; ② During the drilling process, the liquid level must be monitored every 50 pipes. If the liquid level rises or overflows, the well must be shut down in time, and the well must be re-balanced before the operation can be resumed; ③ When implementing hydraulic circulation to treat the wellbore operation, the well-killing fluid is recovered after the drilling tool is lowered into place, and clean water is used for hydraulic circulation. The single pipe is reversed by switching the double semi-sealed blowout preventer. After the treatment is completed, the wellbore pressure is balanced before the drilling operation can be performed.

[0128] Preferably, the specific operation steps for performing downhole operations under the wellbore pressure balance state are:

[0129] 41) Preparation for underground operations. After balancing the pressure and confirming that the wellhead pressure is 0 MPa and there is no overflow, preparation for underground operations is carried out.

[0130] 42) Normal tripping and lowering of the tubing string. By continuously replenishing the well-killing fluid and regularly monitoring the fluid level, normal pressure and overflow-free tripping and lowering can be achieved.

[0131] 421. During the drilling process, the wellbore pressure balance is maintained by using the well pressure fluid.

[0132] 421. When drilling, observation work must be done while on duty. If overflow, well kick or other abnormal conditions occur during the operation, the operation must be stopped immediately, the blowout preventer must be closed, the blowout preventer must be installed quickly, the pressure must be observed, and additional well-killing fluid must be squeezed in to re-establish balance before drilling can be resumed.

[0133] 421. Control the speed of drilling. Start with a slow lifting of the pipe string. As the hanging weight decreases, gradually increase the lifting speed. Within 300 meters from the perforated well section, the speed should not exceed 3 meters per minute. The normal drilling speed should not exceed 5 meters per minute. Drill immediately after drilling. It is strictly forbidden to stop drilling and rest without closing the blowout preventer and empty well inspection equipment. If the equipment fails during drilling, it must be confirmed that the wellhead is in a controlled state before repairing the equipment.

[0134] 421. When drilling is completed and other measures are taken, an oil pipe of no less than 1 / 3 of the well depth must be lowered into the well first, and the wellhead must be properly seated. It is strictly forbidden to stop the well while it is empty.

[0135] 421. During the drilling process, the well-killing fluid should be added every 10-20 roots, and the injection and return volumes should be measured.

[0136] 421. During the drilling process, monitor and record the annular liquid level every 40-50 tubes. If the liquid level rises or overflows, shut down the well in time and resume operations after re-balancing the well.

[0137] 43) Hydraulic circulation treatment wellbore operation. When the well is blocked and sand flushing, drilling and other wellbore treatment operations are required, the well-killing fluid is recovered first. After the well-killing fluid is recovered, the working blowout preventer group is used to control the wellhead, and the single-root operation is achieved by switching the double half seal, and the hydraulic circulation treatment wellbore operation is carried out. After the treatment is completed, the well is killed and the drill is pulled out.

[0138] Preferably, Figure 7 As shown, the step 5) recovers the homogeneous well-killing fluid by using a pulse induced blowback recovery method.

[0139] Specifically, the cement truck performs pulse pressurization and blowout at the wellhead, relying on the reaction force to gradually lift the wellbore liquid column until the wellbore pressure balance is broken, and then the formation pressure is automatically returned to recover the wellbore fluid.

[0140] like Figure 7 As shown in the figure, the pulse induced injection flowback recovery method includes the following steps:

[0141] 51) Inject clean water from the oil pipe and stop the pump when the pressure reaches the set value;

[0142] 52) Release the pressure from the oil pipe, and repeat steps 51) and 52). During the operation, it is necessary to measure the changes in the amount of injected and discharged liquid;

[0143] 53) When the liquid column in the tubing rises to break the wellbore pressure balance and realizes automatic backflow, the operations of steps 51) and 52) are stopped, the wellhead process is switched, and preparation is made to recover the well-killing fluid;

[0144] 54) First, the well-killing fluid in the tubing and near-wellbore formation is automatically spitted out through the tubing; then, the well-killing fluid in the casing annulus is recovered through the casing (it is also possible to first recover the well-killing fluid in the casing annulus and then recover the well-killing fluid in the tubing).

[0145] During the recovery process, the density is continuously monitored. When the density is low, the recovery is stopped and the recovered homogeneous fracturing fluid is stored in the original homogeneous fluid storage tank. The final recovered density and volume are measured and recorded and then used in the next well.

[0146] During the operation, all wellhead processes are hard-connected, the equipment pressure level meets the on-site requirements, the wellhead valve is flexible to open and close, and the maximum operating pressure cannot exceed the minimum value of the wellbore pressure resistance and the formation fracture pressure. Toxic and harmful gases are detected throughout the operation, and the return pressure and displacement of the well-killing fluid are controlled through the throttling and pressure-stabilizing valve to ensure safety and environmental protection.

[0147] Preferably, in step 6), the well is sealed and completed, and the completion string adopts a ball-dropping type sealing string.

[0148] Preferably, in step 7) the homogeneous well-killing fluid is recycled and treated by purifying the returned well-killing fluid online through a homogeneous fluid treatment device, and using the purified well-killing fluid as a base fluid to adjust its density so that it meets the working requirements of the next well.

[0149] Specifically, first, the returned well-killing fluid is purified online through the homogeneous liquid processing device, and the turbid and oil-rich well-killing fluid is filtered and processed into transparent, clear and impurity-free well-killing fluid. Then, according to the relevant data of the next well, the purified well-killing fluid is used as the base fluid to adjust its density so that its density meets the working requirements of the next well.

[0150] Embodiment 1:

[0151] A balanced pressure well repairing method for recovering homogeneous well killing fluid,

[0152] The steps include:

[0153] 1) Determine the density and liquid volume of the homogeneous well-killing fluid according to the production parameters of the water injection well, and calculate the required amounts of base fluid, solvent and solute according to the determined density and liquid volume of the homogeneous well-killing fluid;

[0154] Operation purpose: Efficiently recover homogeneous well-killing fluid to balance pressure and repair the well

[0155] Basic parameters: artificial well bottom 2406m, vertical depth of perforation section upper edge 2194m, daily injection 18m 3 , wellhead pressure 10.4MPa, cumulative water injection volume 20112m 3

[0156] Wellbore condition: No leakage in the casing, the sealing of the tubing is intact, and the backwash channel of the packer is unobstructed.

[0157] Well killing fluid type: high-density homogeneous inorganic well killing fluid.

[0158] Design the required killing fluid density, fluid volume and drug quality: bottom hole pressure 31.9MPa, theoretical killing fluid density ρ 理论 =1.48g / cm 3 .

[0159] According to ρ 理论 gH1=ρ 实际 g(H1-h) calculate ρ 实际 , where ρ 理论 =1.51g / cm 3 , h = 100m, we can get ρ 实际 =1.54g / cm3 .

[0160] The calculated volume of the oil pipe is 7.2m 3 , casing annulus volume 18.8m 3 , the volume of well killing fluid to be supplemented is 2.9m 3 , total volume 28.9m 3 Considering the on-site emergency reserve, the actual volume of well-killing fluid is calculated as 1.5 times the theoretical volume. The total volume of well-killing fluid actually prepared on site is 43.4m 3 , according to the formula, the mass of the required drugs is calculated: 9543kg zinc bromide, 10588kg calcium chloride, 22892kg sodium nitrate, 23.6m water 3 , HS-3 imidazoline quaternary ammonium salt 248kg.

[0161] 2) Use the required base fluid, solvent and solute to prepare the homogeneous well-killing fluid;

[0162] The homogeneous liquid treatment device was used for preparation. The whole preparation process took a total of 8 hours. After the preparation was completed, the volume and density of the well-killing fluid in the tank were measured. The total volume of the well-killing fluid in the tank was 43.4m 3 The density of the well-pressure fluid in the tank is 1.54g / cm 3 The volume and density of the well-killing fluid meet the requirements.

[0163] 3) Use homogeneous well killing fluid and high-pressure water injection well killing method to balance the wellbore pressure;

[0164] Since the casing is not leaking, the string is in good sealing condition, and the backwash channel of the packer is unobstructed, the reverse circulation + positive extrusion well method is used to balance the wellbore pressure. The operation process is as follows: Figure 3 As shown, it mainly includes three steps: the first step is to use 18.8m 3 Implement reverse circulation throttling to balance the casing annulus pressure. During the operation, the tubing backflow pressure is controlled at 8-10MPa, and the casing squeeze pressure is less than 15MPa. After the well is killed, there is no overflow in the tubing annulus, and the tubing annulus pressure is successfully killed. In the second step, the tubing is squeezing the well fluid 10.1m 3 (equal to tubing volume + wellbore volume × 0.1), the squeeze pressure is controlled to be less than 15MPa during the operation. The three-step well shut-in automatically adjusts the wellbore balance. After 15 minutes of shut-in, the measured liquid level depth is 52.0m, there is no overflow at the wellhead, and the well is successfully killed.

[0165] 4) Carry out downhole operations under the wellbore pressure balance state;

[0166] Install the wellhead blowout preventer. After the on-site construction preparation is completed, carry out normal tripping operations according to the downhole operation process. Figure 6The original well pipe string was unsealed, and the drilling speed did not exceed 3m / min. During the drilling process, the fluid was continuously replenished, and the fluid level was monitored every 50 pipes. It took 15.5 hours to replenish 4.3m of homogeneous fluid. 3 , and completely pulled out the 252 oil pipes and downhole tools in the original well. Well clearance regulations The tool tubing was used to drill the well, and the fluid level was monitored every 50 pipes. The well was pulled out after reaching the artificial bottom of the well. The well drilling took 25 hours. The completion string was equipped, and the fluid level was monitored every 50 pipes. It took 11 hours to lower the completion string into place, and then the magnetic positioning depth was calibrated to confirm that the tool position was correct before installing the wellhead.

[0167] 5) Recovering homogeneous well-killing fluid;

[0168] The "pulse induced spray backflow recovery technology" is used to recover the homogeneous liquid. The operation process is as follows: Figure 7 As shown in the figure, the first step is to inject 1.5m of clean water from the oil pipe in large volume. 3 , stop the pump after the pressure reaches the set value of 10MPa; the second step is to quickly release the pressure from the oil pipe, and repeat steps ① and ②. During the operation, observe that the amount of liquid discharged each time is more than the previous amount of liquid discharged in the same backflow time period; the third step is as shown in ③, repeat steps ① and ② for 8 times, which takes 2.5 hours. After breaking the wellbore pressure balance and realizing automatic backflow, stop operations ① and ②, switch the wellhead process, and prepare to recover the wellbore fluid; the fourth step is as shown in ④, first recover the wellbore fluid in the oil pipe and near-well formation through automatic backflow of the oil pipe; then recover the wellbore fluid in the casing annulus through casing backflow (you can also recover the casing annulus first and then the wellbore fluid). The density is continuously monitored during the recovery process, and the density is lower than 1.2g / cm 3 The recovery was stopped when the total amount of recovered 3 Homogeneous liquid 28m 3 .

[0169] 6) Throwing ball to seal the well;

[0170] 7) Recycle and treat homogeneous well-killing fluid.

[0171] Embodiment 2:

[0172] The difference between Example 2 and Example 1 is that the well-killing fluid recovered from the previous well is used as the base fluid to compound the well-killing fluid on site, and the required base fluid and solute dosage are calculated using the empirical value method. The wellbore has a problem of tubing column sealing failure, and the positive squeeze + reverse squeeze well method is used to balance the wellbore pressure. Compared with Example 1, this example has the following advantages: First, it is simpler and more convenient to use the empirical value method to calculate the required base fluid and solute dosage, and the work can be completed by the operating personnel on site; second, the positive squeeze + reverse squeeze well method is used to balance the wellbore pressure, solving the problem that the well with broken and leaking tubing cannot be reversely cycled.

[0173] Embodiment 3:

[0174] A balanced pressure well repairing method for recovering homogeneous well killing fluid comprises the following steps:

[0175] 1) Determine the density and liquid volume of the homogeneous well-killing fluid according to the production parameters of the water injection well, and calculate the required amounts of base fluid, solvent and solute according to the determined density and liquid volume of the homogeneous well-killing fluid;

[0176] Operation purpose: Efficiently recover homogeneous well-killing fluid to balance pressure and repair the well.

[0177] Basic parameters: artificial well bottom 2237m, vertical depth of perforation section upper edge 2134m, daily injection 25m 3 , wellhead pressure 11.2MPa, cumulative water injection volume 72255m 3 .

[0178] Wellbore condition: No leakage in casing, overflow during casing blowout, and failure of tubing seal.

[0179] Well killing fluid type: high-density homogeneous inorganic well killing fluid.

[0180] Design the required killing fluid density, fluid volume and drug quality: bottom hole pressure 32.1MPa, theoretical killing fluid density ρ 理论 =1.54g / cm 3 .

[0181] According to ρ 理论 gH1=ρ 实际 g(H1-h) calculate ρ 实际 , where ρ 理论 =1.51g / cm 3 , h = 50m, we can get ρ 实际 =1.57g / cm 3 .

[0182] The calculated volume of the oil pipe is 6.7m 3 , casing annulus volume 17.4m 3 , the volume of well killing fluid to be supplemented is 2.7m 3 , total volume 26.8m 3 Considering the on-site emergency reserve, the actual volume of well-killing fluid is calculated as 1.5 times the theoretical volume. The total volume of well-killing fluid actually prepared on site is 40.2m 3 .

[0183] The density of the base liquid recovered on site is 1.52g / cm 3 , the total liquid volume is 40m 3 , use the empirical method to calculate the required base liquid and solute

[0184] Dosage:

[0185] Clean water volume V 水 : Calculate the density ρ 配制 =1.57g / cm 3 , volume V 配制 =40.2m 3 When the well-killing fluid is prepared with clean water, the required clean water volume V 水 =V 配制 / (1m 3 Density of clean water ρ=1.57g / cm 3 The volume of the killing fluid obtained);

[0186] Look up the experience value table to get 1m 3 Prepared with clean water 1.57g / cm 3 The volume of the well-killing fluid is 1.99m 3 ;

[0187] Calculate the clean water volume V 水 =20.2m 3 .

[0188] Use clean water to prepare density ρ=1.57g / cm 3 , volume V 配制 =40.2m 3 The dosage of each solute in the well killing fluid:

[0189] m 溶质 ＝ Clean water volume × 1m 3 Density of clean water ρ=1.57g / cm 3 The mass of solute required for the well-killing fluid;

[0190] Look up the experience value table to get 1m 3 Density of clean water ρ=1.57g / cm 3 The solute masses required for the well killing fluid are:

[0191] 1087.9kg calcium nitrate, 660.3kg calcium chloride, 270.7kg potassium chloride.

[0192] Calculate the density ρ 配制 =1.57g / cm 3 , volume V preparation = 40.2m 3 When the well-killing fluid is prepared with clean water, the required amounts of each solute are: 21975.5kg of calcium nitrate, 13338.8kg of calcium chloride, and 5469.0kg of potassium chloride.

[0193] The calculation uses the volume V 水 = 20.2 water preparation density ρ 基液 =1.52g / cm 3When the base liquid is 基液 =V 水 ×1m 3 Density of clean water ρ=1.52g / cm 3 The volume of well killing fluid obtained.

[0194] Look up the experience value table to get 1m 3 Prepared with clean water 1.52g / cm 3 The volume of the well-killing fluid is 1.87m 3 ;

[0195] Get the base liquid volume V 基液 =37.8m 3 .

[0196] Use clean water to prepare density ρ=1.52g / cm 3 , volume V 基液 =37.8m 3 Amount of each solute:

[0197] m 溶质 ＝ Clean water volume × 1m 3 Density of clean water ρ=1.52g / cm 3 The mass of solute required for the well-killing fluid;

[0198] Look up the experience value table to get 1m 3 Density of clean water ρ=1.52g / cm 3 The solute masses required for the well killing fluid are: 995.4kg calcium nitrate, 605.9kg calcium chloride, and 249.0kg potassium chloride.

[0199] The calculated density is ρ = 1.52 g / cm 3 , volume V 基液 =37.8m 3 When the well-killing fluid is prepared with clean water, the required amounts of each solute are: 20107.7kg calcium nitrate, 12240.0kg calcium chloride, and 2029.5kg potassium chloride.

[0200] Calculate the density ρ base liquid = 1.52 g / cm 3 Prepared to a density of 1.57 g / cm 3 The amount of each solute:

[0201] Δm 溶质 =m 压井液溶质 -m 基液溶质

[0202] Δm 硝酸钙 =1867.7kg;

[0203] Δm 氯化钙=1098.7kg;

[0204] Δm 氯化钾 =439.5kg;

[0205] The final working density is ρ = 1.52g / cm 3 The base liquid density is ρ = 1.57 g / cm 3 Volume: 40.2m 3 The base fluid required for the well killing fluid is 37.8m 3 , solutes to be added: 1867.7kg calcium nitrate, 1098.7kg calcium chloride, 439.5kg potassium chloride.

[0206] 2) Use the required base fluid, solvent and solute to prepare the homogeneous well-killing fluid;

[0207] The homogeneous liquid treatment device was used for preparation. The whole preparation process took a total of 4 hours. After the preparation was completed, the volume and density of the well-killing fluid in the tank were measured. The total volume of the well-killing fluid in the tank was 40.2m 3 The density of the well-pressure fluid in the tank is 1.57g / cm 3 The volume and density of the well-killing fluid meet the requirements.

[0208] 3) Use homogeneous well killing fluid and high-pressure water injection well killing method to balance the wellbore pressure;

[0209] Since the sealing of the well string failed, the forward squeeze + reverse squeeze well method was adopted. The operation process is as follows: Figure 4 It mainly includes three steps: the first step is to squeeze the tubing to balance the tubing pressure, use a 700-type cement truck to connect the cement truck and the process steel hard pipeline, test the process pressure at 25MPa, maintain the pressure for 10 minutes without leakage, and squeeze the well-killing fluid from the tubing for 8m 3 The pump pressure was 14-0MPa, the displacement was 200-300L / min, and it took 26 minutes to observe that there was no overflow in the tubing, and the tubing well was successfully killed. The second step was to squeeze the casing back to balance the casing annulus pressure, and the well-killing fluid was squeezed from the casing in reverse circulation for 20m 3 The pump pressure was 15-0MPa, the displacement was 200-300L / min, and it took 67 minutes. After the well was killed, it was observed that there was no overflow in the casing. The three-step well shut-in automatically adjusted the wellbore balance. After 30 minutes of shut-in, the measured liquid level depth was 60.0m. There was no overflow at the wellhead, and the well was killed successfully.

[0210] 4) Carry out downhole operations under the wellbore pressure balance state;

[0211] Install the wellhead blowout preventer. After the on-site construction preparation is completed, carry out normal tripping operations according to the downhole operation process. Figure 6The original well pipe string was unsealed, and the drilling speed did not exceed 3m / min. During the drilling process, the fluid was continuously replenished, and the fluid level was monitored every 50 pipes. It took 15.5 hours to replenish 4.3m of homogeneous fluid. 3 , and completely pulled out the 228 oil pipes and downhole tools from the original well. Well clearance regulations The tool tubing was used to drill the well, and the fluid level was monitored every 50 pipes. The well was pulled out after reaching the artificial bottom of the well. The well drilling took 29 hours. The completion string was equipped, and the fluid level was monitored every 50 pipes. It took 12 hours to lower the completion string into place, and then the magnetic positioning depth was calibrated. After confirming that the tool position was correct, the wellhead was installed.

[0212] 5) Recovering homogeneous well-killing fluid;

[0213] The "pulse induced spray backflow recovery technology" is used to recover the homogeneous liquid. The operation process is as follows: Figure 7 As shown in the figure, the first step is to inject 1.5m of clean water from the oil pipe in large volume. 3 , stop the pump after the pressure reaches the set value of 10MPa; the second step is to quickly release the pressure from the oil pipe, and repeat steps ① and ②. During the operation, observe that the amount of liquid discharged each time is more than the previous amount of liquid discharged in the same backflow time period; the third step is as shown in ③, repeating steps ① and ② for 11 times, which takes 2.8 hours. After breaking the wellbore pressure balance and realizing automatic backflow, stop operations ① and ②, switch the wellhead process, and prepare to recover the wellbore fluid; the fourth step is as shown in ④, first recover the wellbore fluid in the oil pipe and near-well formation through automatic backflow; then recover the wellbore fluid in the casing annulus through casing backflow (you can also recover the casing annulus first and then the wellbore fluid). The density is continuously monitored during the recovery process, and the density is less than 1.2g / cm 3 The recovery was stopped when the total recovery was 1.53 g / cm 3 Homogeneous liquid 27m 3 .

[0214] 6) Pitch the ball to seal the well.

[0215] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "front", "inside", "right", etc. is based on the orientation or positional relationship shown in the drawings, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present invention.

[0216] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A balanced pressure well repairing method for recovering homogeneous well killing fluid, characterized in that: The steps include: 1) Determine the density and liquid volume of the homogeneous well-killing fluid according to the production parameters of the water injection well, and calculate the required amounts of base fluid, solvent and solute according to the determined density and liquid volume of the homogeneous well-killing fluid; 2) Use the required base fluid, solvent and solute to prepare the homogeneous well-killing fluid; 3) Use homogeneous well killing fluid and high-pressure water injection well killing method to balance the wellbore pressure; 4) Carry out downhole operations under the wellbore pressure balance state; 5) Recovering homogeneous well killing fluid; 6) Sealing and completing the well; 7) Recycle and treat homogeneous well-killing fluid.

2. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 1, characterized in that: The required amounts of base liquid, solvent and solute are calculated by combining theoretical calculation with field experiments to produce a table of experience values ​​for liquid preparation of various drug formulations.

3. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 2, characterized in that: The actual volume of the homogeneous well-killing fluid configured is 1.5 times the total volume of the well-killing fluid required by the wellbore according to theoretical calculation.

4. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 1, characterized in that: In step 3), the high-pressure water injection well killing method balances the wellbore pressure and uses one of the three processing methods to complete the well killing, specifically: 31) When the sealing of the tubing in the water injection well is intact and the backwash channel of the packer is unobstructed, the reverse circulation + positive squeeze injection method is used to complete the well killing; 32) When the pipe seal in the water injection well fails or the pipe seal is intact but the backwash channel is blocked, the forward squeeze + reverse squeeze method is used to complete the well killing; 33) When the tubing in the wellbore of an injection well falls off, there is no tubing, and the forward squeeze + reverse squeeze method is unsuccessful, the oil and casing synchronous squeeze injection method is used to complete the well killing.

5. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 4, characterized in that: The above 31) is specifically as follows: prepare for the inspection, first check the casing, when the casing is intact, select the density and amount of the well killing fluid; then check the sealing of the tubing, when the sealing of the tubing is intact, use reverse circulation to balance the annulus, then positive squeeze injection to balance the tubing, and the well killing is completed.

6. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 4, characterized in that: The specific contents of 32) are: Prepare for string inspection. First check the casing. When the casing is intact, select the density and amount of the killing fluid. Then check the sealing of the tubing. When the sealing of the tubing fails, use the tubing to squeeze the killing fluid until the tubing pressure is balanced. The killing is completed. Prepare to inspect the string, first check the casing, when the casing is intact, select the density and amount of the well killing fluid; then check the sealing of the tubing, when the tubing is intact; then check whether the backwash channel is unobstructed, when the backwash channel is not unobstructed, use tubing squeezing to balance the tubing pressure and the well killing is completed.

7. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 4, characterized in that: The specific contents of 33) are: Prepare for string inspection, first check the casing, if the casing is intact, select the density and amount of killing fluid; then check the sealing of the tubing, if the tubing sealing fails, the tubing squeezing and injecting killing fluid cannot balance the tubing pressure, if the tubing has fallen off, use oil and casing synchronous squeezing and injecting until the tubing pressure is balanced, and the killing is completed; Prepare to inspect the string, first check the casing, when the casing is intact, select the density and amount of the well killing fluid; then check the sealing of the tubing, when the tubing is intact; then check whether the backwash channel is unobstructed, when the backwash channel is not unobstructed, the tubing squeeze injection cannot balance the tubing pressure; when the tubing has fallen off, use oil and casing synchronous squeeze injection to balance the tubing pressure, and the well killing is completed.

8. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 4, characterized in that: When situations 31) to 33) do not exist, other string inspection methods or other well repair methods are used, specifically: When preparing for string inspection, first check the casing. When the casing is incomplete; or when the casing is complete, select the density and amount of the well-killing fluid, and then check the sealing of the tubing. When the tubing sealing fails, the tubing pressure cannot be balanced by squeezing the well-killing fluid through the tubing. When the tubing has fallen off, the tubing pressure cannot be balanced by squeezing the tubing and casing simultaneously; or when the tubing pressure cannot be balanced by squeezing the well-killing fluid through the tubing, and the unsealing of the tubing is unsuccessful, other string inspection methods are used. When preparing for string inspection, first check the casing. When the casing is incomplete; or when the casing is complete, select the density and amount of the well-killing fluid, and then check the sealing of the tubing. When the tubing is sealed, then check whether the backwash channel is unobstructed. When the backwash channel is not unobstructed, tubing squeezing cannot balance the tubing pressure. When the tubing has fallen off, the simultaneous squeezing of oil and casing cannot balance the tubing pressure; or after the tubing squeezing and injection of well-killing fluid cannot balance the tubing pressure, and the unsealing of the tubing is unsuccessful, other well repair methods are used.

9. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 1, characterized in that: The step 5) recovers the homogeneous well-killing fluid by using a pulse induced blowback recovery method.

10. The balanced pressure well repairing method for recovering homogeneous well killing fluid according to claim 1, characterized in that: Step 7) Recycling and treating the homogeneous well-killing fluid is to purify the returned well-killing fluid online through a homogeneous fluid treatment device, and use the purified well-killing fluid as a base fluid to adjust its density so that it meets the working requirements of the next well.

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