阅读说明：本技术 一种利用温度响应型封固剂修复套损方法 (Method for repairing casing damage by using temperature response type sealing agent ) 是由 陈祥 赵立强 刘平礼 杜娟 王承杰 安琪 刘金明 王强 虞梦遥 郑雄 于 2021-01-05 设计创作，主要内容包括：本发明公开了一种利用温度响应型封固剂修复穿孔套管的方法,其步骤包括：S1、循环洗井,取油管；S2、下桥塞,坐封,泵送堵球；S3、计算井筒温度场,选择温度响应型封固剂,要求井筒内最大温度T-(1max)小于温度响应型封固剂相变最低温度T-(2min)；S4、计算温度响应型封固剂用量Q-2；S5、向井筒内注入温度响应型封固剂,要求穿孔位置处压力P-2小于地层破裂压力P-F；S6、压胶塞,注顶替液,顶替液量为Q-3；S7、计算温度响应型封固剂相变所需时间t-(wa)；S8、等待t-(wa)时间后,下钻,钻除井筒中预留的封固剂和桥塞。作业全过程注入的均是液体,易注入,不受井型限制,施工难度小,方法简单明确,普遍适用性强。(The invention discloses a method for repairing a perforated casing by using a temperature response type sealing agent, which comprises the following steps: s1, circularly washing the well, and taking an oil pipe; s2, lower bridge plug, setting, and pumping blocking balls; s3, calculating a temperature field of the shaft, selecting a temperature response type sealing agent, and requiring the maximum temperature T in the shaft 1max Less than the lowest phase transition temperature T of the temperature response type sealant 2min (ii) a S4, calculating the using amount Q of the temperature response type sealing agent 2 (ii) a S5, injecting a temperature response type sealing agent into the shaft, and requiring the pressure P at the position of the perforation 2 Less than formation fracture pressure P F (ii) a S6, pressing a rubber plug, and injecting a displacement liquid, wherein the displacement liquid is Q 3 (ii) a S7, calculating the time t required by the phase change of the temperature response type sealing agent wa (ii) a S8, waiting for t wa After a certain time, the well is drilled down and the sealing agent and the bridge plug reserved in the well bore are removed. The liquid is injected in the whole operation process, the injection is easy, the limitation of a well type is avoided, the construction difficulty is small, the method is simple and clear, and the general applicability is strong.)

1. A method of repairing a perforated casing using a temperature responsive sealant, comprising the steps of:

s1, circularly washing the well, and taking an oil pipe;

s2, lower bridge plug, setting, and pumping blocking balls;

s3, calculating a temperature field of the shaft, selecting a temperature response type sealing agent, and requiring the maximum temperature T in the shaft_1maxLess than the lowest phase transition temperature T of the temperature response type sealant_2min；

S4, calculating the using amount Q of the temperature response type sealing agent₂；

S5, injecting a temperature response type sealing agent into the shaft, and requiring the pressure P at the position of the perforation₂Less than formation fracture pressure P_F；

S6, pressing a rubber plug, injecting a displacement liquid and displacing the liquidAmount is Q₃；

S7, calculating the time t required by the phase change of the temperature response type sealing agent_wa；

S8, waiting for t_waAfter the time, the well is drilled down, and the sealing agent and the bridge plug reserved in the well bore are drilled away.

2. The method for repairing perforated casing using temperature-responsive sealant according to claim 1, wherein in step S2, drillable bridge plugs or autolyzed bridge plugs are lowered to a position below the perforated position of the casing by using cables, coiled tubing or conventional tubing, and the distance from the perforated position is 5 to 10 m; and setting the bridge plug, and then pumping the plugging ball to plug the bridge plug.

3. The method of repairing a perforated casing with a temperature responsive sealant according to claim 1 wherein the temperature in the wellbore is specifically calculated as follows in step S3:

q_f1displacement of injection of fluid 1, m³/s；ρ_f1Density of fluid 1, kg/m³；C_f1-the specific heat capacity of fluid 1, J/(kg. DEG C); t is₁-temperature of fluid in the wellbore at ° c; z-well depth at the perforation, m; alpha is alpha₁-convective heat transfer coefficient of fluid 1 and casing wall, W/(m)²·℃)；r₁-the inner radius of the casing, m; t is_casing-casing wall temperature, ° c; u. of_f1-average flow velocity of the cross section of the pipe, m/s; f. of_f1-coefficient of in-pipe on-way friction resistance; t is time, s.

4. The method for repairing a perforated casing with a temperature responsive sealant according to claim 1, wherein in step S4, the amount Q of the temperature responsive sealant is used₂The specific calculation is as follows:

L₁-the occlusion length, m; l is₂-the fluid loss width, m; l is₃-fluid loss height, m; phi-formation porosity,%; h₁-the fluid level, m, is reserved in the tube.

5. The method for repairing a perforated casing using a temperature responsive sealant according to claim 1, wherein the pressure P at the perforation position is at step S5₂The specific calculation is as follows:

q_f2displacement of injection of fluid 2, m³/s；ρ_f2Density of fluid 2, kg/m³；P_inj-the injection pressure, Pa; g-acceleration of gravity, m²S; n is the number of perforations, dimensionless; d-characteristic perforation diameter, m; c is flow coefficient at the position of a perforation, and is dimensionless; u. of_f2The flow velocity of the fluid 2, m/s; mu.s₂-viscosity of fluid 2, Pa · s; delta-drag reduction of fluid 2, dimensionless.

6. The method for repairing a perforated casing using a temperature-responsive sealant according to claim 1, wherein the displacement liquid amount Q is used in step S6₃The specific calculation is as follows:

Q₃＝Q_3-1+πr₁ ²(z-H₁) (4)

Q_3-1ground pipeline volume, m³。

7. The method for repairing a perforated casing using a temperature responsive sealant according to claim 1, wherein the time t required for the phase transition of the temperature responsive sealant is t 7_waIn particular toThe calculation is as follows:

λ₁-thermal conductivity, W/(m. DEG C); c_f2-the specific heat capacity of fluid 2, J/(kg. DEG C); r is₂The outer radius of the casing, m.

Technical Field

The invention relates to the technical field of oil extraction in oil fields, in particular to a casing damage repairing operation generated by casing damage caused by perforation in the process of oil and gas field development.

Background

In the process of oil and gas field exploitation, casing perforation (such as pitting perforation, electrochemical corrosion perforation, scraping and the like) is caused by various reasons, oil and gas flow into a stratum along the perforation position from the inside of a pipe, and if the oil and gas meet a fault, the oil and gas can directly flow out of the ground, so that serious safety accidents are caused, for example, oil leakage accidents in a Bohai Bay are caused, and the oil and gas directly flow into the sea along the fault. Therefore, the problem of casing perforation always troubles the production of oil and gas fields, and serious problems directly cause the production stop and the scrapping of oil and gas wells.

Aiming at the problem of casing damage of the oil and gas well, the repairing method mainly comprises two methods of mechanical reshaping and sealing and plugging by a chemical sealing agent. The literature reports on mechanical plastic sealing are mainly: the horizontal well casing dislocation and casing string repairing method disclosed by patent No. CN201210329397.X, the repairing process of the horizontal well casing dislocation and casing string repairing method disclosed by patent No. CN201310014576.9, the testing method for simulating the repairing process of the deformed casing under the stratum confining pressure, the casing dislocation and casing horizontal well casing string repairing method disclosed by patent No. CN201110321772.1, the special integrated tool for the casing string repairing method disclosed by patent No. CN201110321772.1, the coal-bed gas well casing repairing method disclosed by patent No. CN 201510293777.6, the casing damage well self-expansion rubber patching device disclosed by patent No. CN201611160385.3, the patching method thereof, and the casing repairing agent construction tool and the construction method disclosed by patent No. CN202010630435.X. The mechanical shaping and sealing method has the problems of different inner diameters of the sleeve, limited temperature resistance of rubber sealing, high price of high-temperature-resistant rubber, easy shedding, high construction difficulty and the like. The application method of the casing pipe repairing device disclosed in the patent CN201810084978.9 and the petroleum pipe repairing method disclosed in the patent CN202010085268.5 mainly adopt the principle that the aluminothermic reaction is utilized to melt, seal and re-solidify, so that the operation difficulty is high. The patent CN201110314478.8 discloses a chemical composite resin sealing agent for repairing an oil-water well casing, a variable density pipe external sealing channeling leakage-blocking agent disclosed by the patent CN 201710893066.1 and a preparation method thereof, a preparation method and a construction method of a casing repairing reinforcing agent disclosed by the patent CN201810425492.7, a casing repairing material with high adhesion to metal disclosed by the patent CN202010500662.0 and a preparation method thereof, and provides a chemical sealing casing repairing material, namely a temperature response type sealing agent. The preparation method and the construction method of the casing repairing reinforcing agent disclosed in the patent CN201810425492.7 also refer to a construction method, but the construction method refers to the use of a fishable bridge plug, so that the recovery difficulty is extremely high, and in addition, the waiting curing time is not clear. The construction tool and the construction method for the casing repairing agent disclosed by the patent CN202010630435.X also refer to the construction method, but the construction method needs to be matched with the disclosed construction tool, so that the general applicability is low. In order to solve the problems, the invention provides a method for repairing casing damage by using a temperature response type sealing agent.

Disclosure of Invention

The invention aims to provide a method for repairing casing damage by using a temperature response type sealing agent, aiming at the problems of undefined curing time, limited application range and large construction difficulty.

The invention provides a method for repairing a perforated casing by using a temperature response type sealing agent, which comprises the following steps:

step S1: and circularly washing the well and taking an oil pipe. By circularly washing the well, the temperature of the well shaft is greatly reduced; and taking out the oil pipe, and leaving the optical sleeve for preparation for subsequent operation.

Step S2: and (4) lowering a bridge plug, setting and pumping a plugging ball. Using a cable, a continuous oil pipe or a conventional oil pipe to enable the drillable bridge plug or the autolyzed bridge plug to be arranged below the perforated position of the casing pipe and be 5-10 m away from the perforated position; and setting the bridge plug, and then pumping the plugging ball to plug the bridge plug.

Step S3: calculating the temperature field of the shaft, selecting a temperature response type sealing agent, and requiring the maximum temperature T in the shaft_1maxLess than the lowest phase transition temperature T of the temperature response type sealant_2min. The temperature in the wellbore is specifically calculated as follows:

q_f1displacement of injection of fluid 1, m³/s；ρ_f1Density of fluid 1, kg/m³；C_f1-the specific heat capacity of fluid 1, J/(kg. DEG C); t is₁-temperature of fluid in the wellbore at ° c; z-well depth at the perforation, m; alpha is alpha₁-convective heat transfer coefficient of fluid 1 and casing wall, W/(m)²·℃)；r₁-the inner radius of the casing, m; t is_casing-casing wall temperature, ° c; u. of_f1-average flow velocity of the cross section of the pipe, m/s; f. of_f1-coefficient of in-pipe on-way friction resistance; t is time, s.

Step S4: calculating the amount of temperature responsive sealant Q₂The specific calculation is as follows:

L₁-the occlusion length, m; l is₂-the fluid loss width, m; l is₃-fluid loss height, m; phi-formation porosity,%; h₁-the fluid level, m, is reserved in the tube.

Step S5: injecting a temperature responsive sealant into the wellbore requiring a pressure P at the location of the perforations₂Less than formation fracture pressure P_FThe specific calculation is as follows:

q_f2displacement of injection of fluid 2, m³/s；ρ_f2Flow ofDensity of body 2, kg/m³；P_inj-the injection pressure, Pa; g-acceleration of gravity, m²S; n is the number of perforations, dimensionless; d-characteristic perforation diameter, m; c is flow coefficient at the position of a perforation, and is dimensionless; u. of_f2The flow velocity of the fluid 2, m/s; mu.s₂-viscosity of fluid 2, Pa · s; delta-drag reduction of fluid 2, dimensionless.

Step S6: pressing the rubber plug, injecting displacement liquid, wherein the displacement liquid is Q₃The specific calculation is as follows:

Q_3-1ground pipeline volume, m³。

Step S7: calculating the time t required by the phase change of the temperature response type sealing agent_waThe specific calculation is as follows:

λ₁-thermal conductivity, W/(m. DEG C); c_f2-the specific heat capacity of fluid 2, J/(kg. DEG C); r is₂The outer radius of the casing, m.

Step S8: wait for t_waAfter the time, the well is drilled down, and the sealing agent and the bridge plug reserved in the well bore are drilled away.

In the calculation method, the same symbols related in all formulas have the same meaning, and the symbols are all universal after being labeled once.

The flow of the method for repairing casing damage by using the temperature response type sealant is shown in figure 1.

The invention has the advantages that: (1) the liquid is injected in the whole operation process, so that the injection is easy and is not limited by the well type; (2) the method is simple and clear, and the general applicability is strong; (3) can provide guidance for repairing casing damage by using the temperature response type sealing agent.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a flow chart of a method for repairing casing damage using a temperature responsive sealant.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Examples

Taking the well A of the M oil field as an example, the quality problem and the later collision of the casing pipe cause that a certain position at the well depth of 2695.8-2705.3M is perforated, and the leakage occurs.

Step S1: and (4) taking the oil pipe after circularly washing the well for one well bore volume.

Step S2: and (3) using a coiled tubing to lower the drillable bridge plug to the well depth of 2712.3m, pulling the coiled tubing, setting the bridge plug, and pumping a plugging ball to plug the bridge plug.

Step S3: the early operation is injected with 80m³Liquid, average displacement 0.017m³Fluid density 1032 kg/m/s³The specific heat capacity of the fluid is 4198J/(kg. DEG C.), the well depth of a perforation is 2695.8-2705.3m, 2700.5m is taken, and the convective heat transfer coefficient is 4610W/(m)²DEG C), the inner radius of the casing is 0.08m, the original temperature of the casing wall is the formation temperature, the formation temperature gradient is 3.1 ℃/100m, and the maximum temperature T in the shaft is obtained by calculation_1maxThe temperature was 44.5 ℃. According to the maximum temperature T in the shaft_1maxLess than the lowest phase transition temperature T of the temperature response type sealant_2minThe temperature responsive sealant disclosed in the patent CN201110314478.8 is selected, and the minimum temperature of phase transition is 70 ℃.

Step S4: the plugging length is 5m, the filtration width is 3m, the filtration height is 2m, the formation porosity is 15%, the height of reserved fluid in the pipe is 100m, and the dosage Q of the temperature response type sealing agent₂Is 6.5m³。

Step S5: the fracture pressure of the stratum is 59.3MPa, the injection pressure is 24.5MPa, and the discharge capacity is 0.5m³Min, density 1083kg/m³Is stickyThe degree of the flow rate of the slurry is 32.5 mPas, the resistance reduction rate is 0.65, the flow coefficient of the perforation is 0.56, the number of the perforations is 1, and the characteristic diameter of the perforations is 15.3 m.

Step S6: ground pipeline volume 0.6m³Pressing the rubber plug, and injecting 52.8m³Displacing the liquid.

Step S7: the thermal conductivity coefficient is 36.7W/(m DEG C), the specific heat capacity is 4032J/(kg DEG C), the outer radius of the sleeve is 0.089m, and the time required by phase change of the temperature response type sealing agent is 150 min.

Step S8: and after waiting for 150min, drilling down, removing the sealing agent and the bridge plug reserved in the shaft by drilling, and finishing the operation.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.