A method for an underground controllable heat source and for repairing an oil and gas well

Abstract

The present invention discloses a downhole controllable heat source and a method for repairing oil and gas wells, belonging to the technical field of downhole plugging and repair. To solve the problem of the complex process of the existing oil well casing repair technology, the downhole controllable heat source includes a chemical loading cylinder (101) and an electric ignition component (1). The chemical loading cylinder (101) contains combustion chemicals, and the electric ignition component (1) can ignite the combustion chemicals and make the combustion chemicals continuously burn and release heat. The downhole controllable heat source and the method for repairing oil and gas wells can achieve safe, fast and low-cost well repair operations downhole.

Description

Technical Field

[0001] The invention relates to the technical field of underground plugging and repairing, in particular to an underground controllable heat source and a method for repairing an oil and gas well. Background Art

[0002] When oil and gas wells are at the end of production, the casing will be damaged due to various reasons. When encountering casing damage, the conventional operation method is to mill the part, and then repair the damaged part by re-squeezing cement, etc. The main disadvantages include: 1. The solid formed by the existing cement after solidification has many pores inside, so that the gas can flow out through the pores. Therefore, when using cement to repair oil and gas wells, it is easy to cause the internal gas to be discharged to the ground; 2. During the operation, the blocked wellbore needs to be opened up, and the blocked stratum needs to be drilled out with a drill bit, and the process is relatively complicated; 3. The existing cement plugging process is inseparable from the drilling rig, which makes its construction cost high. Summary of the invention

[0003] In order to solve the above-mentioned problem of complex process for repairing oil well casing, the present invention provides a downhole controllable heat source and a method for repairing oil and gas wells, which can realize safe, fast and low-cost well repair operations downhole.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A controllable underground heat source comprises a medicine filling tube and an electric ignition component. The medicine filling tube contains a combustion medicine, and the electric ignition component can ignite the combustion medicine and make the combustion medicine continue to burn and release heat.

[0006] The medicine filling cylinder is in an upright state, and is a cylindrical structure with both upper and lower ends closed. The outside of the medicine filling cylinder contains a cylinder wall, and the melting point of the cylinder wall is greater than 1600°C. The inside of the medicine filling cylinder contains a medicine containing cavity. The combustion agent contains thermite. The liquid generated by the combustion of the combustion agent cannot flow out of the medicine filling cylinder. The combustion of the combustion agent lasts for 1 minute to 10 minutes.

[0007] The combustion agent comprises a starting charge layer, an upper receiving charge layer, a middle burning charge layer and a lower receiving charge layer which are arranged in sequence from top to bottom, and the combustion intensity of the starting charge layer, the combustion intensity of the upper receiving charge layer, the combustion intensity of the middle burning charge layer and the combustion intensity of the lower receiving charge layer decreases in sequence.

[0008] The starting charge layer contains an ignition charge and an outer receiving charge arranged inside and outside. The electric ignition component is an electric heating rod. The lower end of the electric ignition component is located in the ignition charge. The lower part of the starting charge layer is a conical structure with the top facing downward and the bottom facing upward. The upper part of the upper receiving charge layer is also a conical structure with the top facing downward and the bottom facing upward. The starting charge layer is matched and connected with the upper receiving charge layer.

[0009] The ignition powder contains charcoal powder and / or saltpeter powder, the external support powder contains thermite and a binder, and the external support powder is in a block shape as a whole.

[0010] The upper receiving charge layer, the middle burning charge layer and the lower receiving charge layer all contain thermite, flame retardant and adhesive, and the upper receiving charge layer, the middle burning charge layer and the lower receiving charge layer are block-shaped as a whole.

[0011] The combustion agent contains a plurality of middle-layer combustion powder layers arranged in sequence from top to bottom, a receiving and ignition powder layer is arranged between the upper receiving powder layer and the uppermost middle-layer combustion powder layer, a receiving and ignition powder layer is also arranged between two adjacent middle-layer combustion powder layers, and a receiving and ignition powder layer is also arranged between the lower receiving powder layer and the lowermost middle-layer combustion powder layer.

[0012] The medicine filling cylinder also contains an upper flame retardant medicine layer, which is stacked and connected with the starting medicine layer.

[0013] The medicine filling tube also comprises a lower flame retardant medicine layer, which is stacked and connected with the lower receiving medicine layer.

[0014] The lower part of the lower receiving medicine layer is a conical structure with the top facing upward and the bottom facing downward, and the upper part of the lower flame retardant medicine layer is also a conical structure with the top facing upward and the bottom facing downward. The lower flame retardant medicine layer is matched and connected with the lower receiving medicine layer.

[0015] A plurality of support blocks are arranged at the lower end of the medicine filling cylinder, and the plurality of support blocks are arranged at intervals along the circumference of the medicine filling cylinder. The outer ends of the support blocks are exposed to the outer circumferential surface of the medicine filling cylinder. The support blocks are connected to the medicine filling cylinder by a spring, and the support blocks can move back and forth along the diameter direction of the medicine filling cylinder.

[0016] A method for repairing an oil and gas well, wherein the method adopts the above-mentioned downhole controllable heat source, and the method for repairing an oil and gas well comprises the following steps:

[0017] Step 1: Lower the downhole controllable heat source to the damaged part of the casing, so that an annular cavity is formed between the downhole controllable heat source and the casing;

[0018] Step 2, filling well repairing particles into the annular cavity;

[0019] Step 3: The electric ignition component ignites the combustion agent and causes the combustion agent to continue to burn and release heat, and the well repairing particles are melted to form liquid and flow into the damaged part;

[0020] Step 4: The liquid solidifies to form a sealing layer.

[0021] The beneficial effects of the present invention are:

[0022] It is only necessary to lower the cables and electric cables with the downhole controllable heat source into the designated position, and through the activated block-shaped agent structure, the heat source is provided, and the casing and the annulus cement ring are melted to a certain extent to form a plugging layer. The agent and the method of use do not require large-scale drilling equipment, etc., only the ground cable car and industrial power supply are needed, and the time required for plugging is relatively short. Therefore, the downhole controllable heat source and the method for repairing oil and gas wells can significantly reduce the operation time of oil and gas wells and reduce the cost of plugging oil and gas wells. In summary, the downhole controllable heat source and the method for repairing oil and gas wells provided by the present invention have the characteristics of good sealing, high operating efficiency, and low construction cost, which can greatly improve the plugging effect of oil and gas wells and form a safe and efficient metal plugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 It is an internal schematic diagram of the controllable underground heat source described in the present invention.

[0025] Figure 2 It is a cross-sectional schematic diagram of the controllable underground heat source of the present invention.

[0026] Figure 3 It is a schematic diagram of lowering the downhole controllable heat source to the damaged part of the casing.

[0027] Figure 4 It is a schematic diagram of well repair particles being melted to form liquid and flowing into the damaged area.

[0028] Figure 5 It is a schematic diagram of forming a blocking layer.

[0029] The following are the descriptions of the reference numerals:

[0030] 1. Electric ignition components; 2. Upper flame retardant layer; 3. Starting layer; 4. Starting melting zone; 5. Upper receiving layer; 6. Receiver ignition layer; 7. Middle combustion layer; 8. Lower receiving layer; 9. Lower flame retardant layer; 10. Underground controllable heat source;

[0031] 31. Ignition charge; 32. External receiving charge;

[0032] 101, Agent Loading Cylinder; 102, Wellbore Cement; 103, Casing; 104, Damaged Area; 105, Sealing Layer; 106, Workover Granules; 107, Support Block; 108, Spring; 109, Surface Control Console. Detailed Embodiment

[0033] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0034] A downhole controllable heat source includes an agent loading cylinder 101 and an electric ignition component 1. The agent loading cylinder 101 contains a combustion agent, and the electric ignition component 1 can ignite the combustion agent and make the combustion agent continuously burn and release heat, as Figure 1 and Figure 2 shown.

[0035] The inventive point of the present invention is that workover granules 106 are filled between the downhole controllable heat source and the damaged area 104 of the casing 103. The combustion agent in the downhole controllable heat source is ignited and made to continuously burn and release heat. The released heat melts the workover granules 106 into an alloy liquid with a certain viscosity in a flowing state. The alloy liquid flows into the damaged area 104 (i.e., holes and breakages), and after cooling, the alloy liquid solidifies to fill the damaged area 104, thereby realizing the repair of the casing 103 of the oil and gas well.

[0036] In this embodiment, the agent loading cylinder 101 is in an upright state. The agent loading cylinder 101 is a cylindrical structure with both upper and lower ends closed. The outside of the agent loading cylinder 101 has a cylinder wall, and the melting point of the cylinder wall is greater than 1600 °C. The inside of the agent loading cylinder 101 has an agent accommodation cavity, and the combustion agent is located in the agent accommodation cavity.

[0037] During implementation, the agent loading cylinder 101 can reach a predetermined downhole position by lowering a wire rope or a tubing string. The combustion agent (containing thermite) can provide a high-temperature melting heat source after combustion. The material of the agent loading cylinder 101 (i.e., the cylinder wall) can be made of materials with a relatively high melting point and high refractoriness, such as tungsten alloy, aluminum alloy, etc.

[0038] The function of the combustion of the combustion agent is to continuously burn and release heat, use the released heat to heat the workover granules 106 and melt the workover granules 106. The liquid generated by the combustion of the combustion agent cannot flow out of the agent loading cylinder 101, and the combustion time of the combustion agent lasts for 1 minute to 10 minutes.

[0039] In this embodiment, the agent filling cylinder 101 also contains ignition charge 31, and the electric ignition component 1 can ignite the combustion agent through the ignition charge 31. That is, the electric ignition component 1 can ignite the ignition charge 31, and the combustion agent is ignited after the ignition charge 31 is burned.

[0040] In this embodiment, the combustion agent comprises a starting charge layer 3, an upper receiving charge layer 5, a middle burning charge layer 7 and a lower receiving charge layer 8 which are arranged in sequence from top to bottom. The combustion intensity of the starting charge layer 3, the combustion intensity of the upper receiving charge layer 5, the combustion intensity of the middle burning charge layer 7 and the combustion intensity of the lower receiving charge layer 8 decrease in sequence (become slower in sequence), such as Figure 1 and Figure 2 shown.

[0041] That is, the combustion intensity of the starting charge layer 3 is greater than that of the upper supporting charge layer 5, the combustion intensity of the upper supporting charge layer 5 is greater than that of the middle burning charge layer 7, and the combustion intensity of the middle burning charge layer 7 is greater than that of the lower supporting charge layer 8.

[0042] For example, the combustion intensity of the lower receiving charge layer 8 is level one, the combustion intensity of the middle burning charge layer 7 is level two, the combustion intensity of the upper receiving charge layer 5 is level three, and the combustion intensity of the starting charge layer 3 is level four. The higher the level, the more intense the combustion. The combustion intensity includes the combustion speed and the combustion temperature. The starting charge layer 3, the upper receiving charge layer 5, the middle burning charge layer 7 and the lower receiving charge layer 8 can realize rapid start-up, stable take-over, main heating and slow stop accordingly.

[0043] The starting charge layer 3 starts burning quickly, and the upper receiving charge layer 5 and the middle burning charge layer 7 realize combustion connection. Each part of the charge can self-propagate from top to bottom after ignition, and the lower receiving charge layer 8 burns slowly, and is finally terminated by the flame retardant. The starting charge layer 3, the upper receiving charge layer 5, the middle burning charge layer 7 and the lower receiving charge layer 8 all contain thermite and flame retardant. Thermite contains aluminum powder and iron oxide powder. The general property of thermite is that the higher the purity and the smaller the particle size, the higher the release temperature and the intensity of the reaction. The intensity affects the combustion speed and the combustion temperature. Generally speaking, the maximum temperature of thermite can reach 2000°C.

[0044] The purpose of adding flame retardant to the combustion agent is to adjust the different combustion intensities of the starting charge layer 3, the upper receiving charge layer 5, the middle burning charge layer 7 and the lower receiving charge layer 8, that is, to control the combustion temperature and speed of the starting charge layer 3, the upper receiving charge layer 5, the middle burning charge layer 7 and the lower receiving charge layer 8. The flame retardant can be made of inorganic materials such as ceramic powder, silicon dioxide, aluminum oxide and other materials that will not decompose at high temperature or produce subordinate reactions with the thermite itself, so as to reduce the thermite content.

[0045] By changing the ratio of thermite and flame retardant in the starting charge layer 3, the upper receiving charge layer 5, the middle burning charge layer 7 and the lower receiving charge layer 8 and the particle size of the aluminum powder in thermite, the combustion intensity of the starting charge layer 3, the upper receiving charge layer 5, the middle burning charge layer 7 and the lower receiving charge layer 8 can be changed accordingly, and the specific combustion intensity can be obtained through a limited number of experiments.

[0046] In this embodiment, along the diameter direction of the medicine filling tube 101, the starting charge layer 3 includes the ignition charge 31 and the outer receiving charge 32 arranged inside and outside, that is, the ignition charge 31 is located inside the starting charge layer 3. The combustion intensity of the ignition charge 31 and the combustion intensity of the outer receiving charge 32 are both greater than the combustion intensity of the upper receiving charge layer 5.

[0047] The electric ignition component 1 is an electric heating rod. The lower end of the electric ignition component 1 is located in the ignition charge 31, and the upper end of the electric ignition component 1 is located outside the medicine filling tube 101. The electric ignition component 1 is in the shape of an upright rod, and the electric ignition component 1 passes through the upper end of the medicine filling tube 101. The electric ignition component 1 reaches the ignition temperature through a small current and a small voltage, so that the ignition charge can be started stably. The advantage is that it can be started through ground control, and does not require complex equipment layout or process parameters, such as Figure 1 and Figure 2 shown.

[0048] The ignition charge 31 is cylindrical, the outer receiving charge 32 is cylindrical, the lower part of the starting charge layer 3 is a conical structure with the top facing downward and the bottom facing upward, and the upper part of the upper receiving charge layer 5 is also a conical structure with the top facing downward and the bottom facing upward, and the starting charge layer 3 is matched with the upper receiving charge layer 5 and is stacked and connected. The conical structure is used for the starting charge to start quickly and then burn stably.

[0049] In this embodiment, the reagents in the reagent filling tube 101 are mainly divided into igniter and combustion agent. The combustion agent can be an existing thermite. The combustion reaction of the combustion agent is thermite reaction, which can realize the underground oxygen-free start, reduce gas release, and ensure the underground pressure balance. The igniter includes ignition agent 31, which can be black powder. For example, the ignition agent 31 contains charcoal powder and / or saltpeter powder. The combustion agent includes an outer receiving agent 32, an upper receiving agent layer 5, a middle combustion agent layer 7 and a lower receiving agent layer 8.

[0050] The outer receiving charge 32 may contain (or not contain) a flame retardant. The outer receiving charge 32 also contains a binder (such as paraffin). The outer receiving charge 32 can be made into an integral block (such as a cylindrical) structure after mixing thermite and paraffin. The outer receiving charge 32, the upper receiving charge layer 5, the middle combustion charge layer 7, and the lower receiving charge layer 8 all contain thermite. The outer receiving charge 32, the upper receiving charge layer 5, the middle combustion charge layer 7, and the lower receiving charge layer 8 also all contain a binder (such as paraffin). The role of the binder is to form the combustion agent into a whole. The outer receiving charge 32, the upper receiving charge layer 5, the middle combustion charge layer 7, and the lower receiving charge layer 8 are all made into an integral block (such as a cylindrical) structure after mixing thermite, a flame retardant, and paraffin. The specific addition content ratio of the binder can be obtained through a limited number of experiments.

[0051] In this embodiment, the combustion agent contains a plurality of middle combustion charge layers 7 arranged in sequence from top to bottom. A receiving ignition charge layer 6 is arranged between the upper receiving charge layer 5 and the uppermost middle combustion charge layer 7. A receiving ignition charge layer 6 is also arranged between two adjacent middle combustion charge layers 7. A receiving ignition charge layer 6 is also arranged between the lower receiving charge layer 8 and the lowermost middle combustion charge layer 7.

[0052] The receiving ignition charge layer 6 is an ignition agent, that is, the ignition agent also includes the receiving ignition charge layer 6. The composition and content of the receiving ignition charge layer 6 can be the same as those of the ignition charge 31. The receiving ignition charge layer 6 can be black powder. For example, the ignition charge 31 contains charcoal powder and / or saltpeter powder. The role of the receiving ignition charge layer 6 is to ignite the next layer of the combustion agent and ensure the continuity of combustion.

[0053] In this embodiment, the medicine loading cylinder 101 also contains an upper flame retardant layer 2 and a lower flame retardant layer 9. The upper flame retardant layer 2 and the starting charge layer 3 are stacked and connected up and down. The lower flame retardant layer 9 and the lower receiving charge layer 8 are stacked and connected up and down. The upper flame retardant layer 2 and the lower flame retardant layer 9 can be made of materials that are not easily combustible and can achieve thermal isolation, such as silicon dioxide or magnesium hydroxide, as Figure 1 and Figure 2 shown.

[0054] The lower part of the lower receiving charge layer 8 is a conical structure with the top facing up and the bottom facing down. The upper part of the lower flame retardant layer 9 is also a conical structure with the top facing up and the bottom facing down. The lower flame retardant layer 9 and the lower receiving charge layer 8 are stacked and connected in a matching manner. The conical structure can gradually slow down the exothermic reaction of the medicine combustion and achieve automatic termination of the medicine, as Figure 1 and Figure 2 shown.

[0055] In this embodiment, a plurality of support blocks 107 are provided at the lower end of the chemical agent loading cylinder 101. The plurality of support blocks 107 are arranged at intervals along the circumferential direction of the chemical agent loading cylinder 101. The outer ends of the support blocks 107 expose the outer peripheral surface of the chemical agent loading cylinder 101. The support blocks 107 are connected to the chemical agent loading cylinder 101 through springs 108. The support blocks 107 can reciprocate in the diametrical direction of the chemical agent loading cylinder 101, and the support blocks 107 can adaptively expand and contract.

[0056] The outer ends of the support blocks 107 can block the following workover particles 106 from falling, facilitating the retention and filling of the workover particles 106 in the annular cavity formed between the chemical agent loading cylinder 101 and the casing 103. To improve the filling effect, the outer ends of the support blocks 107 can be arc-shaped strips (top view). To facilitate the detachment of the downhole controllable heat source from the casing 103 after the workover operation, the outer peripheral surface of the chemical agent loading cylinder 101 can be an inclined surface. The outer diameter of the upper end of the chemical agent loading cylinder 101 is greater than the outer diameter of the lower end of the chemical agent loading cylinder 101. The support blocks 107 can be shear pins, and the outer ends of the support blocks 107 are the heads of the shear pins.

[0057] Next, a method for repairing an oil and gas well is introduced. The method for repairing an oil and gas well uses the above-mentioned downhole controllable heat source 10. The method for repairing an oil and gas well includes the following steps:

[0058] Preparation work: The upper end of the chemical agent loading cylinder 101 is connected to one end of a wire rope or a tubing. One end of a cable is connected to the electric ignition component 1. The cable can be sleeved inside the wire rope or the tubing. The other end of the cable is connected to the ground control console 109.

[0059] Step 1: Lower the downhole controllable heat source 10 to the damaged part 104 (such as a hole) of the casing 103 through the wire rope or the tubing. There is wellbore cement 102 outside the casing 103. An annular cavity is formed between the downhole controllable heat source 10 and the casing 103, as Figure 3 shown.

[0060] Step 2: Fill the annular cavity with workover particles 106. The material of the workover particles 106 is a ferrous alloy, and the melting point of the workover particles 106 is 600°C - 700°C.

[0061] Step 3: The ground console 109 raises the temperature of the electric ignition component 1 above the ignition point of the ignition agent 31. The electric ignition component 1 ignites the ignition agent 31, and the ignition agent 31 burns to form a starting melting zone 4. The ignition agent 31 burns and then ignites the combustion agent, and the combustion agent continuously burns and releases heat in the order from top to bottom (the starting agent layer 3, the upper receiving agent layer 5, the middle layer combustion agent layer 7, and the lower receiving agent layer 8 burn in sequence). The temperature between the agent loading cylinder 101 and the casing 103 is about 800°C - 900°C, and the inner surface temperature of the casing 103 is about 800°C. The workover particles 106 are melted by the released heat to form a liquid, which makes the casing in a solid-liquid coexistence state at high temperature. The liquid flows into the damaged part 104, such as Figure 4 shown.

[0062] Step 4: The liquid solidifies to form a sealing layer 105. The material of the sealing layer 105 is an alloy, such as Figure 5 shown. The melting repair effect is achieved, the leakage path is sealed, and the downhole repair of the casing damage well is realized. The heat source agent can be combined with other thermal melting materials for combined plugging of perforations.

[0063] Step 5: The agent loading cylinder 101 is lifted by a wire rope or a tubing, and the agent loading cylinder 101 is separated from the sealing layer 105, completing the repair operation of the casing 103.

[0064] As described above, only the specific embodiments of the present invention are provided, and the scope of the invention implementation cannot be limited by them. Therefore, the replacement of equivalent components or the equivalent changes and modifications made according to the protection scope of the present invention patent should still fall within the scope covered by this patent. In addition, the technical features in the present invention can be freely combined with each other between technical features, between technical features and technical solutions, between technical solutions and technical solutions, and between embodiments and embodiments.

Claims

1. An underground controllable heat source, characterized in that, The underground controllable heat source comprises a reagent filling cylinder (101) and an electric ignition component (1), wherein the reagent filling cylinder (101) contains a combustion reagent, and the electric ignition component (1) is capable of igniting the combustion reagent and causing the combustion reagent to continuously burn and release heat; The combustion agent comprises a starting charge layer (3), an upper receiving charge layer (5), a middle burning charge layer (7) and a lower receiving charge layer (8) which are arranged in sequence from top to bottom, and the combustion intensity of the starting charge layer (3), the combustion intensity of the upper receiving charge layer (5), the combustion intensity of the middle burning charge layer (7) and the combustion intensity of the lower receiving charge layer (8) decrease in sequence; The combustion agent lasts for 1 minute to 10 minutes; The lower part of the starting medicine layer (3) is a conical structure with the top facing downward and the bottom facing upward, and the upper part of the upper receiving medicine layer (5) is also a conical structure with the top facing downward and the bottom facing upward. The starting medicine layer (3) is matched and connected with the upper receiving medicine layer (5).

2. The downhole controllable heat source according to claim 1, wherein, The medicine filling cylinder (101) is in an upright state. The medicine filling cylinder (101) is a cylindrical structure with both upper and lower ends closed. The outside of the medicine filling cylinder (101) contains a cylinder wall, and the melting point of the cylinder wall is greater than 1600° C. The inside of the medicine filling cylinder (101) contains a medicine containing cavity. The combustion medicine contains aluminum thermite, and the liquid generated by the combustion of the combustion medicine cannot flow out of the medicine filling cylinder (101).

3. The downhole controllable heat source according to claim 1, wherein The starting charge layer (3) comprises an ignition charge (31) and an outer receiving charge (32) which are arranged inside and outside the starting charge layer. The electric ignition component (1) is an electric heating rod. The lower end of the electric ignition component (1) is located inside the ignition charge (31).

4. The downhole controllable heat source according to claim 3, characterized in that, The ignition charge (31) contains charcoal powder and / or saltpeter powder, the external receiving charge (32) contains thermite and a binder, and the external receiving charge (32) is in a block shape as a whole.

5. The downhole controllable heat source according to claim 1, wherein The upper receiving charge layer (5), the middle burning charge layer (7) and the lower receiving charge layer (8) all contain thermite, flame retardant and adhesive, and the upper receiving charge layer (5), the middle burning charge layer (7) and the lower receiving charge layer (8) are block-shaped as a whole.

6. The downhole controllable heat source according to claim 1, characterized in that, The combustion agent comprises a plurality of middle combustion charge layers (7) arranged in sequence from top to bottom, a receiving and ignition charge layer (6) is arranged between the upper receiving charge layer (5) and the uppermost middle combustion charge layer (7), a receiving and ignition charge layer (6) is also arranged between two adjacent middle combustion charge layers (7), and a receiving and ignition charge layer (6) is also arranged between the lower receiving charge layer (8) and the lowermost middle combustion charge layer (7).

7. The downhole controllable heat source according to claim 1, wherein, The medicine filling tube (101) also contains an upper flame retardant medicine layer (2), and the upper flame retardant medicine layer (2) is connected to the starting medicine layer (3) in an upper and lower stacked manner.

8. The downhole controllable heat source according to claim 1, wherein The medicine filling tube (101) also contains a lower flame retardant medicine layer (9), which is connected to the lower receiving medicine layer (8) in a stacked manner.

9. The downhole controllable heat source according to claim 8, wherein, The lower portion of the lower receiving medicine layer (8) is a conical structure with the top facing upward and the bottom facing downward, and the upper portion of the lower flame retardant medicine layer (9) is also a conical structure with the top facing upward and the bottom facing downward, and the lower flame retardant medicine layer (9) is matched and connected with the lower receiving medicine layer (8).

10. The downhole controllable heat source according to claim 1, wherein, A plurality of support blocks (107) are provided at the lower end of the medicament loading cylinder (101). The plurality of support blocks (107) are arranged at intervals along the circumferential direction of the medicament loading cylinder (101). The outer ends of the support blocks (107) expose the outer peripheral surface of the medicament loading cylinder (101). The support blocks (107) are connected to the medicament loading cylinder (101) through springs (108). The support blocks (107) can reciprocate in the diametrical direction of the medicament loading cylinder (101).

11. A method for repairing an oil and gas well, characterized in that, The method for repairing an oil and gas well uses the downhole controllable heat source (10) described in claim 1. The method for repairing an oil and gas well includes the following steps: Step 1: Lower the downhole controllable heat source (10) to the damaged part (104) of the casing (103), and an annular cavity is formed between the downhole controllable heat source (10) and the casing (103); Step 2: Fill the annular cavity with workover particles (106); Step 3: The electric ignition component (1) ignites the combustion medicament and causes the combustion medicament to continuously burn and release heat. The workover particles (106) are melted to form a liquid and flow into the damaged part (104); Step 4: The liquid solidifies to form a sealing layer (105).

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