A downhole ignition device and method for burning oil layer

Abstract

The present application discloses an underground ignition device and method for burning oil layers, belonging to the field of crude oil exploitation. The second cylinder of the ignition device is sleeved on the first cylinder to form a first annular cavity; the movable rod of the ignition assembly is inserted into the first cylinder, and the front end face is connected to the mounting plate; a plurality of mounting through holes are arranged on the mounting plate; a protective sleeve is clamped in each mounting through hole; an ignition nozzle is arranged in each protective sleeve; a cooling cavity is formed between the inner wall of the front end of the protective sleeve and the inner wall of the front end of the ignition nozzle; a first temperature and pressure detection structure is arranged on the front end face of the mounting plate; the interlayer is sleeved on the front end of the second cylinder, wherein the cavity is connected to the first annular cavity; a plurality of vents are arranged on the outer wall; the mounting plate is clamped on the front end of the inner cavity of the second cylinder and can extend out of the interlayer shell or be retracted into the inner cavity of the second cylinder under the drive of the movable rod; the gas delivery mechanism is connected to the first annular cavity. The present application can protect the ignition nozzle and reduce the temperature around the ignition nozzle.

Description

Technical Field

[0001] The present application relates to the technical field of crude oil extraction, and in particular to a downhole ignition device and method for burning oil layers. Background Art

[0002] In the process of extracting crude oil from deep wells such as horizontal wells and vertical wells, the crude oil recovery efficiency is reduced due to the high viscosity of the crude oil at the far end of the well. In order to reduce the viscosity of the crude oil at the far end of the well, it is usually necessary to ignite the crude oil at the well so that the heat of the near-end crude oil is transferred to the far-end crude oil after ignition, thereby reducing the viscosity of the far-end crude oil and ultimately improving the extraction efficiency of the crude oil at the well.

[0003] Electric heating ignition is one of the most commonly used methods for igniting downhole crude oil in the prior art. The principle is to lower an electric heater into a deep well and discharge heat or ignite the crude oil through the electric heater to cause the crude oil near the downhole to burn.

[0004] However, in the existing electric heating ignition technology, the electric heater is often affected by factors such as underground high temperature, vibration, and impact and resistance of foreign objects during underground hoisting and lowering, and the electric heater often fails to ignite. Even if the ignition is successful, the high temperature conditions underground can easily cause the electric heater to fail. Summary of the invention

[0005] The embodiments of the present application provide an underground ignition device and method for burning oil layers, which can solve the problem that existing electric heaters are affected by factors such as high temperature and vibration underground, and impact and resistance of foreign objects during underground lifting and lowering. The electric heaters often fail to ignite. Even if the ignition is successful, the high temperature conditions underground can easily cause the electric heater to fail.

[0006] In order to achieve the above object, the technical solution of the embodiment of the present invention is:

[0007] In the first aspect, an embodiment of the present invention provides a downhole ignition device for burning oil layers, comprising a first cylinder, a second cylinder, an ignition assembly, a first temperature and pressure detection structure, a sandwich shell, a gas delivery mechanism and a control mechanism; the second cylinder is sleeved on the first cylinder so that the front end face of the first cylinder is located in the inner cavity of the second cylinder, and the outer wall of the first cylinder and the inner wall of the second cylinder are spaced a preset distance apart to form a first annular cavity; the ignition assembly comprises a movable rod, a mounting plate, a protective sleeve and an ignition nozzle; the movable rod is inserted into the first cylinder, and the front end face is connected to the mounting plate; a plurality of mounting through holes are provided on the mounting plate; a protective sleeve is clamped in each of the mounting through holes; an ignition nozzle is provided in each of the protective sleeves, and the ignition nozzle is connected to an ignition controller outside the well through an ignition cable; the protective sleeve A cooling cavity is formed between the inner wall of the front end and the inner wall of the front end of the ignition nozzle, and the inner wall of the protective sleeve in contact with the rear end of the ignition nozzle is provided with a plurality of axial through grooves, and the plurality of axial through grooves connect the first annular cavity and the cooling cavity; the first temperature and pressure detection structure is arranged on the front end surface of the mounting disk and is electrically connected to the control mechanism; the sandwich shell is cylindrical, the front end is an arc surface, and a hollow cavity is arranged between the outer wall and the inner wall, which is sleeved on the front end of the second cylinder; the hollow cavity is connected with the first annular cavity; the outer wall is provided with a plurality of air vents connecting the hollow cavity and the outside world; the mounting disk is clamped at the front end of the inner cavity of the second cylinder and can extend out of the sandwich shell or be retracted into the inner cavity of the second cylinder under the drive of the movable rod; the gas delivery mechanism is connected with the first annular cavity, and is configured to deliver supporting combustion gas or cooling protective gas to the first annular cavity.

[0008] In combination with the first aspect, in a possible implementation, the downhole ignition device for burning oil layers also includes a protective tube and a peripheral combustion condition detection and adjustment mechanism; the protective tube is open at one end and closed at the other end, and a clamping hole is provided on the closed surface; the second cylinder is passed through the clamping hole so that the protective tube is sleeved on the second cylinder, and a second annular cavity is formed between the outer wall of the second cylinder and the inner wall of the protective tube; the gas delivery mechanism is connected to the second annular cavity and is configured to deliver cooling protective gas to the second annular cavity; the peripheral combustion condition detection and adjustment mechanism includes multiple groups, and the multiple groups of the peripheral combustion condition detection and adjustment mechanisms are arranged in a circular array around the central axis of the protective tube; each group of the peripheral combustion condition detection and adjustment mechanism includes an expansion arm structure, a temperature and pressure resistant tube and a second temperature and pressure detection structure; the second temperature and pressure detection structure is arranged on the expansion arm structure and is electrically connected to the control mechanism, and the expansion arm structure can adjust the distance between the second temperature and pressure detection structure and the central axis of the second cylinder; one end of the temperature and pressure resistant tube is connected to the second annular cavity, and the other end is arranged around the second temperature and pressure detection structure.

[0009] In combination with the first aspect, in a possible implementation manner, the distances between the multiple expansion arm structures are adjusted to be different.

[0010] In combination with the first aspect, in a possible implementation, the expansion arm structure includes a slide rail, a counterweight, a traction assembly, a first arm, a mounting seat and a second arm; the slide rail is arranged on the outer wall of the second cylinder, and the extension direction is parallel to the central axis of the second cylinder; the counterweight is slidably arranged on the slide rail; one end of the traction assembly is connected to the counterweight, and the other end is connected to the hoisting mechanism outside the well; one end of the first arm is hinged to the counterweight, and the other end is connected to the mounting seat; one end of the second arm is connected to the mounting seat, and the other end is hinged to the front end of the slide rail.

[0011] In combination with the first aspect, in a possible implementation, the downhole ignition device for burning oil layers also includes a first straightening ring and / or a second straightening ring; the first straightening ring is sleeved on the outer wall of the first cylinder; the second straightening ring is sleeved on the outer wall of the second cylinder.

[0012] In combination with the first aspect, in a possible implementation, the ignition assembly also includes a connecting tube, a clamping cylinder and a limiting ring; the rear end of the protective sleeve is connected to one of the connecting tubes; a clamping cylinder is sleeved on the outside of each of the connecting tubes; the clamping cylinder is clamped in the inner cavity of the second cylinder, and the rear end face is located in front of the connection point between the hollow cavity and the first ring cavity; one end of the connecting tube passes through the clamping cylinder and is sleeved with a limiting ring, and the outer diameter of the limiting ring is larger than the inner diameter of the clamping cylinder; the axial through groove connects the connecting tube and the cooling cavity.

[0013] In combination with the first aspect, in a possible implementation, the downhole ignition device for burning the oil layer also includes a top cover and a push rod; one end of the push rod is fixedly connected to the end of the movable rod facing away from the mounting plate, and the other end is connected to the top cover; the top cover is located outside the rear end surface of the first cylinder; the gas delivery mechanism can pass through the top cover to communicate with the first annular cavity.

[0014] In combination with the first aspect, in a possible implementation, the ignition assembly further includes a diffusion contact grid; and a diffusion contact grid is disposed at the front end of each ignition nozzle.

[0015] In a second aspect, another embodiment of the present invention provides a method for igniting a fire-burning oil layer downhole, based on the above-mentioned fire-burning oil layer downhole ignition device, comprising:

[0016] A protective sleeve is clamped in each mounting through hole of the mounting plate, and an ignition nozzle is arranged in each of the protective sleeves. The ignition nozzle is tested for ignition through an ignition cable. If the ignition nozzle is tested for ignition normally, the front end surface of the movable rod is connected to the mounting plate, and the first temperature and pressure detection structure is arranged on the front end surface of the mounting plate and electrically connected to the control mechanism;

[0017] The second cylinder is sleeved on the first cylinder so that the front end surface of the first cylinder is located in the inner cavity of the second cylinder, and the outer wall of the first cylinder and the inner wall of the second cylinder are spaced at a preset distance to form a first annular cavity;

[0018] The movable rod is inserted into the first cylinder, the mounting plate is clamped at the front end of the inner cavity of the second cylinder, the interlayer shell is sleeved at the front end of the second cylinder, and the gas delivery mechanism is connected to the first annular cavity.

[0019] The ignition device is hoisted and lowered, and during the process, cooling protection gas is delivered to the first cavity through the gas delivery mechanism;

[0020] After the ignition device is hoisted and lowered to a predetermined depth underground, the mounting plate is pushed by a movable rod so that the front end of the ignition nozzle extends out of the sandwich housing;

[0021] The gas delivery mechanism delivers the combustion-supporting gas into the first annular cavity and ignites the ignition nozzle through the ignition cable;

[0022] Ignition is successful, and the first temperature and pressure parameters of the area around the ignition nozzle are detected by the first temperature and pressure detection structure. The control mechanism receives the first temperature and pressure parameters transmitted by the first temperature and pressure detection structure to control the gas delivery mechanism to deliver cooling protective gas to the first annular cavity. The cooling protective gas enters the hollow cavity of the sandwich shell and is ejected from the vent to form a first protective gas film around the ignition nozzle.

[0023] In combination with the second aspect, in one possible implementation, if the first temperature and pressure parameters continue to be abnormal, the movable rod is moved backward to retract the mounting plate into the inner cavity of the second cylinder, and at the same time, cooling protective gas is transported to the cooling cavity through the second annular cavity to form a second protective gas film around the ignition nozzle.

[0024] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0025] The downhole ignition device for burning oil layers provided by the embodiment of the present invention, when actually used, first sets the ignition nozzle in the protective sleeve for protection, then clamps the mounting plate on which the ignition nozzle is mounted at the front end of the inner cavity of the second cylinder, so that the mounting plate is retracted into the inner cavity of the second cylinder, so that during the process of hoisting and lowering the ignition device, the second cylinder can provide structural protection for the ignition nozzle, reduce the damage to the ignition nozzle caused by the vibration downhole, the impact of foreign objects and the resistance during the process of hoisting and lowering downhole. At the same time, the cooling protective gas is delivered to the first annular cavity through the gas delivery mechanism, so that the cooling protective gas surrounds the ignition nozzle, and during the process of hoisting and lowering downhole, it is ensured that the ignition nozzle is not damaged by high temperature. In addition, the interlayer shell is sleeved on the front end of the second cylinder, which can further provide structural protection for the ignition nozzle during the process of hoisting and lowering the ignition device. After the ignition device is hoisted and lowered to a predetermined depth downhole, the mounting plate is pushed by the movable rod so that the front end of the ignition nozzle extends out of the interlayer shell. The gas delivery mechanism delivers combustion-supporting gas to the first annular cavity and ignites the ignition nozzle through the ignition cable, which greatly improves the success rate of downhole ignition and can quickly help the ignition nozzle ignite the near-end crude oil. After the ignition is successful, the first temperature and pressure parameters of the area around the ignition nozzle are detected by the first temperature and pressure detection structure. The control mechanism receives the first temperature and pressure parameters transmitted by the first temperature and pressure detection structure to control the gas delivery mechanism to deliver cooling protective gas to the first annular cavity and adjust the flow and temperature of the cooling protective gas. After the cooling protective gas enters the hollow cavity of the sandwich shell, it is ejected from the vent hole to form a first protective gas film around the ignition nozzle, which can reduce the temperature around the ignition nozzle and prevent high temperature from damaging the ignition nozzle and avoiding its failure. The embodiment of the present application can realize deep well safe ignition operation, and at the same time, effectively protect the first annular cavity during the process of hoisting and lowering the ignition device to the underground or dragging it out of the well, and can perform real-time temperature and pressure detection on the ignition center point and the surrounding area during the underground ignition process, and protect the structure of the ignition device in real time according to the detected temperature, so as to ensure the safety and reliability of the underground ignition work. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0027] Figure 1 A schematic diagram of the structure of the downhole ignition device for burning oil layers provided in the embodiment of the present application Figure 1 (The expansion arm structure adjusts the distance between the second temperature and pressure detection structure and the central axis of the second cylinder to be larger);

[0028] Figure 2A schematic diagram of the structure of the downhole ignition device for burning oil layers provided in the embodiment of the present application Figure 2 (The expansion arm structure adjusts the distance between the second temperature and pressure detection structure and the central axis of the second cylinder to be smaller);

[0029] Figure 3 for Figure 1 The enlarged view of the M in the middle;

[0030] Figure 4 The front end diagram of the downhole ignition device for burning oil layers provided in the embodiment of the present application is shown in FIG. Figure 1 (The mounting plate is retracted into the inner cavity of the second cylinder);

[0031] Figure 5 The front end diagram of the downhole ignition device for burning oil layers provided in the embodiment of the present application Figure 2 (The mounting plate extends out of the sandwich housing).

[0032] Icons: 1-first cylinder; 2-second cylinder; A-first annular cavity; 3-ignition assembly; 31-movable rod; 32-mounting plate; 33-protective sleeve; 34-ignition nozzle; 35-connecting pipe; 36-fixed cylinder; 37-limiting ring; 38-diffusion contact net, D-cooling cavity; 4-first temperature and pressure detection structure; 5-sandwich shell; 51-outer wall; 52-inner wall; 53-vent; B-hollow cavity; 6-gas delivery Mechanism; 7-protection tube; C-second ring cavity; 8-external combustion condition detection and adjustment mechanism; 81-expansion arm structure; 811-slide rail; 812-counterweight block; 813-traction assembly; 814-first arm; 815-mounting seat; 816-second arm; 82-temperature and pressure resistant tube; 83-second temperature and pressure detection structure; 9-first righting ring; 10-second righting ring; 20-top cover; 30-push rod; 40-limit sleeve. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the embodiments of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present invention. The terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0035] The downhole ignition device for burning oil layers provided in the embodiment of the present application can be used in both horizontal wells and vertical wells.

[0036] Please refer to Figures 1 to 5 As shown, an embodiment of the present invention provides a downhole ignition device for burning oil layers, including a first cylinder 1, a second cylinder 2, an ignition assembly 3, a first temperature and pressure detection structure 4, an interlayer shell 5, a gas delivery mechanism 6 and a control mechanism.

[0037] The second cylinder 2 is sleeved on the first cylinder 1 so that the front end of the first cylinder 1 is located in the inner cavity of the second cylinder 2. The outer wall of the first cylinder 1 and the inner wall of the second cylinder 2 are spaced by a preset distance to form a first annular cavity A. Figures 1 to 5 The following refers to Figures 1 to 5 As shown above.

[0038] like Figure 1 and Figure 2As shown, the ignition assembly 3 includes a movable rod 31, a mounting plate 32, a protective sleeve 33 and an ignition nozzle 34. The movable rod 31 is inserted into the first barrel 1, and the front end face is connected to the mounting plate 32. The front end face of the movable rod 31 can be connected to the mounting plate 32 by a mortise and tenon structure, or by a threaded connection. A plurality of mounting through holes are provided on the mounting plate 32. A protective sleeve 33 is clamped in each mounting through hole. An ignition nozzle 34 is arranged in each protective sleeve 33, and the ignition nozzle 34 is connected to an ignition controller outside the well through an ignition cable. The protective sleeve 33 can protect the ignition nozzle 34 from external impact, and can also clamp the ignition nozzle 34, making it convenient for the ignition nozzle 34 to be installed in the mounting through hole. A cooling cavity D is formed between the inner wall of the front end of the protective sleeve 33 and the outer wall of the front end of the ignition nozzle 34. The inner wall of the protective sleeve 33 in contact with the rear end of the ignition nozzle 34 is provided with a plurality of axial through grooves, which connect the first annular cavity A and the cooling cavity D.

[0039] The first temperature and pressure detection structure 4 is disposed on the front end surface of the mounting plate 32 and is electrically connected to the control mechanism. The first temperature and pressure detection structure 4 can detect the temperature and pressure around the ignition nozzle 34 .

[0040] like Figures 1 to 5 As shown, the interlayer shell 5 is cylindrical, with a curved front end, and a hollow cavity B is provided between the outer wall 51 and the inner wall 52, which is sleeved on the front end of the second cylinder 2. The front end of the interlayer shell 5 is a curved surface, which can reduce the resistance of the front end of the ignition device during the process of hoisting and lowering the ignition device.

[0041] The hollow cavity B is connected to the first annular cavity A. For example, a first through hole can be opened on the inner wall 52 of the sandwich shell 5, and a second through hole can be opened on the cylinder wall of the second cylinder 2. When the sandwich shell 5 is sleeved on the front end of the second cylinder 2, the first through hole and the second through hole are butted, so that the hollow cavity B of the sandwich shell 5 can be connected to the first annular cavity A. Of course, a temperature-resistant pipeline can also be set between the hollow cavity B and the first annular cavity A to connect the two.

[0042] The outer wall 51 is provided with a plurality of vents 53 connecting the hollow cavity B and the outside. The mounting plate 32 is clamped at the front end of the inner cavity of the second cylinder 2 and can extend out of the sandwich housing 5 or be retracted into the inner cavity of the second cylinder 2 under the drive of the movable rod 31. Specifically, when the movable rod 31 moves forward, it can drive the mounting plate 32 to extend out of the sandwich housing 5. When the movable rod 31 moves backward, it can drive the mounting plate 32 to be retracted into the inner cavity of the second cylinder 2. The mounting plate 32 is clamped in the inner cavity of the second cylinder 2, and can play the role of maintaining a preset distance between the first cylinder 1 and the second cylinder 2 to form a first annular cavity.

[0043] The gas delivery mechanism 6 is in communication with the first annular cavity A, and is configured to deliver combustion-supporting gas or cooling protection gas to the first annular cavity A. The combustion-supporting gas may be oxygen, and the cooling protection gas may be low-temperature nitrogen.

[0044] The first cylinder 1 and the second cylinder 2 are made of a temperature-resistant alloy, so that the first cylinder 1 and the second cylinder 2 can withstand a temperature greater than or equal to 800°C.

[0045] The downhole ignition device for burning oil layers provided by the embodiment of the present invention, when actually used, first sets the ignition nozzle 34 in the protective sleeve 33 for protection, and then clamps the mounting plate 32 on which the ignition nozzle 34 is mounted at the front end of the inner cavity of the second cylinder 2, so that the mounting plate 32 is retracted into the inner cavity of the second cylinder 2, so that during the process of hoisting and lowering the ignition device, the second cylinder 2 can provide structural protection for the ignition nozzle 34, and reduce the damage to the ignition nozzle 34 caused by the vibration downhole, the impact of foreign objects and the resistance during the process of hoisting and lowering downhole. At the same time, the cooling protective gas is delivered to the first annular cavity A through the gas delivery mechanism 6, so that the cooling protective gas surrounds the ignition nozzle 34, and during the process of hoisting and lowering downhole, it is ensured that the ignition nozzle 34 is not damaged by high temperature. In addition, the interlayer shell 5 is sleeved on the front end of the second cylinder 2, which can further provide structural protection for the ignition nozzle 34 during the process of hoisting and lowering the ignition device. After the ignition device is hoisted and lowered to a predetermined depth underground, the mounting plate 32 is pushed by the movable rod 31 so that the front end of the ignition nozzle 34 extends out of the interlayer shell 5. The gas delivery mechanism 6 delivers combustion-supporting gas to the first annular cavity A and ignites the ignition nozzle 34 through the ignition cable, which greatly improves the success rate of underground ignition and can quickly help the ignition nozzle 34 ignite the near-end crude oil. After the ignition is successful, the first temperature and pressure parameters of the area around the ignition nozzle 34 are detected by the first temperature and pressure detection structure 4. The control mechanism receives the first temperature and pressure parameters transmitted by the first temperature and pressure detection structure 4 to control the gas delivery mechanism 6 to deliver cooling protective gas to the first annular cavity A and adjust the flow rate and temperature of the cooling protective gas. After the cooling protective gas enters the hollow cavity B of the interlayer shell 5, it is ejected from the vent 53 to form a first protective gas film around the ignition nozzle 34, which can reduce the temperature around the ignition nozzle 34, prevent high temperature damage to the ignition nozzle 34, and avoid its failure. The embodiment of the present application can realize safe ignition operations in deep wells, and at the same time, effectively protect the ignition assembly 3 during the process of hoisting the ignition device down into the well or dragging it out of the well. It can also perform real-time temperature and pressure detection on the ignition center point and the surrounding area during the underground ignition process, and protect the structure of the ignition device in real time according to the detected temperature, thereby ensuring the safety and reliability of underground ignition work.

[0046] The downhole ignition device for burning oil layers in the embodiment of the present invention further includes a protective tube 7 and a peripheral combustion condition detection and adjustment mechanism 8. The protective tube 7 is open at one end and closed at the other end, and a clamping hole is provided on the closed surface. The second cylinder 2 is penetrated through the clamping hole so that the protective tube 7 is sleeved on the second cylinder 2, and a second annular cavity C is formed between the outer wall of the second cylinder 2 and the inner wall of the protective tube 7. The gas delivery mechanism 6 is connected to the second annular cavity C, and is configured to deliver cooling protective gas to the second annular cavity C. The peripheral combustion condition detection and adjustment mechanism 8 includes a plurality of groups, and the plurality of groups of peripheral combustion condition detection and adjustment mechanisms 8 are arranged in a circular array around the central axis of the protective tube 7. For example, the peripheral combustion condition detection and adjustment mechanism 8 may include three groups.

[0047] Each set of peripheral combustion condition detection and adjustment mechanism 8 includes an expansion arm structure 81, a temperature and pressure resistant tube 82 and a second temperature and pressure detection structure 83. The second temperature and pressure detection structure 83 is arranged on the expansion arm structure 81 and is electrically connected to the control mechanism. The expansion arm structure 81 can adjust the distance between the second temperature and pressure detection structure 83 and the central axis of the second cylinder 2. One end of the temperature and pressure resistant tube 82 is connected to the second annular cavity C, and the other end is arranged around the second temperature and pressure detection structure 83.

[0048] The protective tube 7 is made of a heat-resistant alloy, and its tolerance temperature is greater than or equal to 1000°C, ensuring that the protective tube 7 can withstand the high temperature and high pressure during the underground ignition process and can protect the second cylinder 2. The clamping hole of the protective tube 7 forms a ring platform at the rear end of the protective tube 7, so that a stable second annular cavity C is formed between the protective tube 7 and the second cylinder 2. In actual use, the second temperature and pressure detection structure 83 is arranged on the expansion arm structure 81, and the expansion arm structure 81 can adjust the distance between the second temperature and pressure detection structure 83 and the central axis of the second cylinder 2, so that the second temperature and pressure detection structure 83 can measure the second temperature and pressure parameters around the ignition device. One end of the heat-resistant and pressure-resistant tube 82 is connected to the second annular cavity C, and the other end is arranged around the second temperature and pressure detection structure 83. The control mechanism receives the second temperature and pressure parameters transmitted by the second temperature and pressure detection structure 83 and controls the gas delivery mechanism 6 to deliver cooling protective gas to the second annular cavity C. The cooling protective gas is delivered from the temperature and pressure resistant pipe 82 to the surrounding area of ​​the second temperature and pressure detection structure 83, thereby reducing the temperature around the ignition device and making the temperature around the ignition device within an appropriate range.

[0049] Optionally, the ignition device further includes a plurality of vertical plates, the number of which is consistent with the number of the expansion arm structures 81. The vertical plates are clamped with the second annular cavity C, dividing the second annular cavity C into a plurality of sub-cavities consistent with the number of the expansion arm structures 81, each sub-cavity is connected to a temperature and pressure resistant pipe 82 and is connected to the gas delivery mechanism 6, and a solenoid valve is arranged therein, thereby increasing the delivery efficiency of the cooling protection gas.

[0050] Furthermore, the multiple expansion arm structures 81 are adjusted to different distances apart, so that the temperature in different ranges around the ignition device can be measured. The existing electric heater can only detect the temperature of the ignition center underground, and cannot detect the combustion of the oil layer in a larger range around the ignition center, which brings hidden dangers to the reliable operation of the underground ignition operation. By arranging multiple expansion arm structures 81 with different expansion radii outside the protective tube 7, the expansion of the expansion arm structure 81 drives the second temperature and pressure detection structure 83 to move to the crude oil combustion area close to or away from the central axis of the second cylinder 2, thereby achieving effective detection of the crude oil combustion in a wider range underground, providing sufficient protection for the safe operation of the ignition device underground.

[0051] For example, when there are three expansion arm structures 81, the expansion range of the first expansion arm structure 81 is 1m~2m away from the central axis of the second cylinder 2, and the normal temperature range of the detection area is 600℃~800℃. The expansion range of the second expansion arm structure 81 is 2m~5m away from the central axis of the second cylinder 2, and the normal temperature range of the detection area is 500℃~600℃. The expansion range of the third expansion arm structure 81 is 5m~8m away from the central axis of the second cylinder 2, and the normal temperature range of the detection area is 400℃~500℃. By expanding three expansion arm structures 81 with different radii, it is ensured that the three first temperature and pressure detection structures 4 can perform temperature and pressure detection in a wider area underground, thereby providing guarantee for the normal operation of the ignition device.

[0052] like Figure 1 and Figure 2 As shown, the expansion arm structure 81 includes a slide rail 811, a counterweight 812, a traction assembly 813, a first arm 814, a mounting seat 815 and a second arm 816. The slide rail 811 is arranged on the outer wall of the second cylinder 2, and the extension direction is parallel to the central axis of the second cylinder 2. The counterweight 812 is slidably arranged on the slide rail 811. One end of the traction assembly 813 is connected to the counterweight 812, and the other end is connected to the hoisting mechanism outside the well. One end of the first arm 814 is hinged to the counterweight 812, and the other end is connected to the mounting seat 815. One end of the second arm 816 is connected to the mounting seat 815, and the other end is hinged to the front end of the slide rail 811. The protective tube 7 can facilitate the setting of the slide rail 811.

[0053] like Figure 1As shown, when the arm structure 81 needs to be expanded to adjust the distance between the second temperature and pressure detection structure 83 and the central axis of the second cylinder 2, the hoisting mechanism loosens the traction assembly 813, allowing the counterweight block 812 to move forward along the slide rail 811. The first arm 814 rotates around the hinge axis hinged to the counterweight block 812, and the second arm 816 rotates around the hinge axis at the front end of the slide rail 811. The distance between the second temperature and pressure detection structure 83 and the central axis of the second cylinder 2 becomes larger, and the second temperature and pressure detection structure 83 can measure the temperature and pressure at a longer distance around the ignition device. Figure 2 As shown, when it is necessary to expand the support arm structure 81 to adjust the distance between the second temperature and pressure detection structure 83 and the central axis of the second cylinder 2 to be smaller, the winch mechanism pulls the traction assembly 813 to make the counterweight block 812 move backward along the slide rail 811, and the first support arm 814 rotates around the hinge axis hinged to the counterweight block 812, and the second support arm 816 rotates around the hinge axis hinged to the front end of the slide rail 811. The distance between the second temperature and pressure detection structure 83 and the central axis of the second cylinder 2 becomes smaller, and the second temperature and pressure detection structure 83 can measure the temperature and pressure at a closer distance around the ignition device.

[0054] Furthermore, a limiting sleeve 40 is sleeved on the outer wall of the protection tube 7 at the end of the slide rail 811 to prevent the counterweight 812 from escaping from the slide rail 811 .

[0055] Continue to refer to Figure 1 and Figure 2 As shown, the downhole ignition device for burning oil layers also includes a first straightening ring 9 and / or a second straightening ring 10. The first straightening ring 9 is sleeved on the outer wall of the first cylinder 1. The second straightening ring 10 is sleeved on the outer wall of the second cylinder 2. By arranging the first straightening ring 9 and the second straightening ring 10, it is possible to ensure that the first cylinder 1 and the second cylinder 2, and the second cylinder 2 and the protective tube 7 maintain a coaxial straightening state during the lifting and lowering of the ignition device, thereby ensuring the stability of the cavity structures of the first ring cavity A and the second ring cavity C.

[0056] like Figures 1 to 5 As shown, the ignition assembly 3 also includes a connecting tube 35, a clamping cylinder 36 and a limiting ring 37. A connecting tube 35 is connected to the rear end of the protective sleeve 33. A clamping cylinder 36 is sleeved on the outside of each connecting tube 35. The clamping cylinder 36 is clamped in the inner cavity of the second cylinder 2, and the rear end surface is located in front of the connection point between the hollow cavity B and the first annular cavity A. A limiting ring 37 is sleeved after one end of the connecting tube 35 passes through the clamping cylinder 36, and the outer diameter of the limiting ring 37 is larger than the inner diameter of the clamping cylinder 36. The axial through groove connects the connecting tube 35 and the cooling cavity D.

[0057] During the actual lifting and lowering of the ignition device, Figure 4As shown, the ignition nozzle 34 located on the mounting plate 32 is protected in the inner cavity of the second cylinder 2, and the cooling protective gas is delivered to the first annular cavity A through the gas delivery mechanism 6. The cooling protective gas is delivered to the cooling cavity D through the connecting pipe 35 and the plurality of axial through grooves on the protective sleeve 33, and the cooling protective gas cools and protects the ignition nozzle 34. At this time, the rear end of the connecting pipe 35 and the limit ring 37 are located behind the connection point between the hollow cavity B and the first annular cavity A, which can ensure that most of the cooling gas enters the cooling cavity D. When the ignition device is hoisted and lowered to a predetermined depth underground, as shown in FIG. Figure 5 As shown, the mounting plate 32 is pushed by the movable rod 31 so that the front end of the ignition nozzle 34 extends out of the sandwich shell 5. The gas delivery mechanism 6 delivers the combustion-supporting gas into the first annular cavity A and ignites the ignition nozzle 34 through the ignition cable. When the ignition is successful, the first temperature and pressure parameters of the area around the ignition nozzle 34 are detected by the first temperature and pressure detection structure 4. The control mechanism receives the first temperature and pressure parameters transmitted by the first temperature and pressure detection structure 4 and controls the gas delivery mechanism 6 to deliver the cooling protective gas to the first annular cavity A. After the cooling protective gas enters the hollow cavity B of the sandwich shell 5, it is ejected from the vent hole 53 to form a first protective gas film around the ignition nozzle 34. At this time, since the clamping cylinder 36 is clamped in the inner cavity of the second cylinder 2, the rear end face is located in front of the connection point between the hollow cavity B and the first annular cavity A. After one end of the connecting tube 35 passes through the clamping cylinder 36, a limiting ring 37 is sleeved. The outer diameter of the limiting ring 37 is larger than the inner diameter of the clamping cylinder 36, thereby ensuring that the rear end of the connecting tube 35 is located in front of the connection point and will not block the connection point. The combustion-supporting gas and cooling protection gas transported from the first annular cavity A can be transported from the first annular cavity A to the hollow cavity B of the sandwich shell 5 and then ejected from the vent hole 53 to perform combustion-supporting or cooling around the ignition nozzle 34.

[0058] Furthermore, if Figure 1 and Figure 2 As shown, the downhole ignition device for burning oil layers also includes a top cover 20 and a push rod 30. One end of the push rod 30 is fixedly connected to one end of the movable rod 31 away from the mounting plate 32, and the other end is connected to the top cover 20. Specifically, one end of the push rod 30 and one end of the movable rod 31 away from the mounting plate 32 can be fixedly connected by a mortise and tenon structure or a threaded connection.

[0059] The top cover 20 is located outside the rear end surface of the first cylinder 1. The gas delivery mechanism 6 can pass through the top cover 20 to communicate with the first annular cavity A. Specifically, a connection hole is provided at a position corresponding to the top cover 20 and the first annular cavity A to communicate the gas delivery mechanism 6 with the first annular cavity A. When the ignition device further includes a protection tube 7, a connection hole is also provided at a position corresponding to the top cover 20 and the second annular cavity C to communicate the gas delivery mechanism 6 with the second annular cavity C.

[0060] The arrangement of the top cover 20 and the push rod 30 can reduce the length of the movable rod 31 , thereby facilitating the installation of the movable rod 31 .

[0061] like Figures 1 to 5 As shown, the ignition assembly 3 also includes a diffusion contact net 38. A diffusion contact net 38 is provided at the front end of each ignition nozzle 34. By providing the diffusion contact net 38, the ignition triggering area can be increased, further ensuring that the ignition nozzle 34 can smoothly perform the underground ignition operation.

[0062] Another embodiment of the present invention provides a method for igniting an oil layer underground by fire, which is based on the above-mentioned device for igniting an oil layer underground by fire and includes the following steps 1 to 7, wherein the sequence number of the steps does not represent the order of execution.

[0063] Step 1: A protective sleeve 33 is fixed in each mounting through hole of the mounting plate 32, and an ignition nozzle 34 is set in each protective sleeve 33. The ignition nozzle 34 is tested for ignition through an ignition cable. If the test ignition of the ignition nozzle 34 is normal, the front end surface of the movable rod 31 is connected to the mounting plate 32, and the first temperature and pressure detection structure 4 is set on the front end surface of the mounting plate 32 and electrically connected to the control mechanism.

[0064] When the ignition assembly 3 further includes a connecting tube 35, a clamping tube 36 and a limiting ring 37, the rear end of the protective sleeve 33 is connected to a connecting tube 35. A clamping tube 36 is sleeved on the outside of each connecting tube 35. The clamping tube 36 is clamped in the inner cavity of the second cylinder 2, and the rear end surface is located in front of the connection point between the hollow cavity B and the first annular cavity A. After one end of the connecting tube 35 passes through the clamping tube 36, a limiting ring 37 is sleeved, and the outer diameter of the limiting ring 37 is larger than the inner diameter of the clamping tube 36. The axial through groove connects the connecting tube 35 and the cooling cavity D.

[0065] Step 2: The second cylinder 2 is sleeved on the first cylinder 1 so that the front end surface of the first cylinder 1 is located in the inner cavity of the second cylinder 2. The outer wall 51 of the first cylinder 1 and the inner wall 52 of the second cylinder 2 are spaced at a preset distance to form a first annular cavity A.

[0066] When the ignition device further includes the first straightening ring 9 , before the second cylinder 2 is sleeved on the first cylinder 1 , the first straightening ring 9 is sleeved on the first cylinder 1 .

[0067] When the ignition device also includes a protective tube 7 and a peripheral combustion condition detection and adjustment mechanism 8, step 2 also includes passing the second cylinder 2 through a card hole set on the closed surface of the protective tube 7, so that the protective tube 7 is sleeved on the second cylinder 2, and a second annular cavity C is formed between the outer wall 51 of the second cylinder 2 and the inner wall 52 of the protective tube 7, and the gas delivery mechanism 6 is connected to the second annular cavity C. A plurality of groups of peripheral combustion condition detection and adjustment mechanisms 8 are arranged in a circular array around the central axis of the protective tube 7. The second temperature and pressure detection structure 83 is arranged on the expansion arm structure 81 and is electrically connected to the control mechanism. The distance between the second temperature and pressure detection structure 83 and the central axis of the second cylinder 2 is adjusted by the expansion arm structure 81. One end of the temperature and pressure resistant tube 82 is connected to the second annular cavity C, and the other end is arranged around the second temperature and pressure detection structure 83.

[0068] Further, the expansion arm structure 81 includes a slide rail 811, a counterweight 812, a traction assembly 813, a first arm 814, a mounting seat 815 and a second arm 816. The slide rail 811 is set on the outer wall 51 of the second cylinder 2, and the extension direction is parallel to the central axis of the second cylinder 2. The counterweight 812 is slidably set on the slide rail 811. One end of the traction assembly 813 is connected to the counterweight 812, and the other end is connected to the hoisting mechanism outside the well. One end of the first arm 814 is hinged to the counterweight 812, and the other end is connected to the mounting seat 815. One end of the second arm 816 is connected to the mounting seat 815, and the other end is hinged to the front end of the slide rail 811.

[0069] When the ignition device further includes a second straightening ring 10 , before the protection tube 7 is sleeved on the second cylinder 2 , the second straightening ring 10 is sleeved on the second cylinder 2 .

[0070] Step 3: Insert the movable rod 31 into the first cylinder 1, clamp the mounting plate 32 at the front end of the inner cavity of the second cylinder 2, retract the mounting plate 32 into the inner cavity of the second cylinder 2, sleeve the interlayer shell 5 on the front end of the second cylinder 2, and connect the gas delivery mechanism 6 to the first annular cavity A.

[0071] When the ignition device includes a top cover 20 and a push rod 30, one end of the push rod 30 is fixedly connected to the end of the movable rod 31 away from the mounting plate 32, and the other end is connected to the top cover 20. The top cover 20 is located outside the rear end surface of the first cylinder 1. The gas delivery mechanism 6 can pass through the top cover 20 and communicate with the first annular cavity A.

[0072] When the ignition assembly 3 further includes a diffusion contact 38 , a diffusion contact 38 is disposed at the front end of each ignition nozzle 34 .

[0073] Step 4: Lift and lower the ignition device, and in the process, convey cooling protective gas into the first cavity through the gas conveying mechanism 6. Since a cooling cavity D is formed between the inner wall of the front end of the protective sleeve 33 and the inner wall of the front end of the ignition nozzle 34, the inner wall of the protective sleeve 33 in contact with the rear end of the ignition nozzle 34 is provided with a plurality of axial through grooves, and the plurality of axial through grooves connect the first annular cavity A and the cooling cavity D. At this time, the cooling protective gas can be located in the first cavity and conveyed to the cooling cavity D through the axial through grooves. The cooling protective gas surrounds the ignition nozzle 34 to cool it down, thereby protecting the ignition nozzle from damage by high temperature.

[0074] Step 5: After the ignition device is hoisted and lowered to a predetermined depth underground, the mounting plate 32 is pushed by the movable rod 31 so that the front end of the ignition nozzle 34 extends out of the sandwich housing 5 .

[0075] Step 6: The gas delivery mechanism 6 delivers combustion-supporting gas to the first annular cavity A and ignites the ignition nozzle 34 through the ignition cable, so that the ignition nozzle 34 can ignite the proximal crude oil and transfer heat to the distal crude oil, thereby reducing the viscosity of the distal crude oil and improving the extraction efficiency of the downhole crude oil.

[0076] Step 7: When ignition is successful, the first temperature and pressure parameters of the area around the ignition nozzle 34 are detected by the first temperature and pressure detection structure 4. The control mechanism receives the first temperature and pressure parameters transmitted by the first temperature and pressure detection structure 4 and controls the gas delivery mechanism 6 to deliver cooling protective gas to the first annular cavity A. After the cooling protective gas enters the hollow cavity B of the sandwich shell 5, it is ejected from the vent hole 53 to form a first protective gas film around the ignition nozzle 34, so that the temperature around the ignition nozzle 34 is maintained at an appropriate level.

[0077] In the underground ignition method for burning oil layers of the embodiment of the present application, the ignition nozzle 34 is first set in the protective sleeve 33 for protection, and then the mounting plate 32 on which the ignition nozzle 34 is installed is clamped at the front end of the inner cavity of the second cylinder 2, so that the mounting plate 32 is retracted into the inner cavity of the second cylinder 2, so that during the process of hoisting and lowering the ignition device, the second cylinder 2 can provide structural protection for the ignition nozzle 34, and reduce the damage to the ignition nozzle 34 caused by underground vibration, foreign object impact and resistance during underground hoisting and lowering. At the same time, the cooling protective gas is delivered to the first annular cavity A through the gas delivery mechanism 6, so that the cooling protective gas surrounds the ignition nozzle 34, and during the underground hoisting and lowering process, the ignition nozzle 34 is ensured not to be damaged by high temperature. In addition, the interlayer shell 5 is sleeved on the front end of the second cylinder 2, which can further provide structural protection for the ignition nozzle 34 during the process of hoisting and lowering the ignition device. After the ignition device is hoisted and lowered to a predetermined depth underground, the mounting plate 32 is pushed by the movable rod 31 so that the front end of the ignition nozzle 34 extends out of the interlayer shell 5. The gas delivery mechanism 6 delivers combustion-supporting gas to the first annular cavity A and ignites the ignition nozzle 34 through the ignition cable, which greatly improves the success rate of underground ignition and can quickly help the ignition nozzle 34 ignite the near-end crude oil. After the ignition is successful, the first temperature and pressure parameters of the area around the ignition nozzle 34 are detected by the first temperature and pressure detection structure 4. The control mechanism receives the first temperature and pressure parameters transmitted by the first temperature and pressure detection structure 4 to control the gas delivery mechanism 6 to deliver cooling protective gas to the first annular cavity A and adjust the flow rate and temperature of the cooling protective gas. After the cooling protective gas enters the hollow cavity B of the interlayer shell 5, it is ejected from the vent 53 to form a first protective gas film around the ignition nozzle 34, which can reduce the temperature around the ignition nozzle 34, prevent high temperature damage to the ignition nozzle 34, and avoid its failure. The embodiment of the present application can realize safe ignition operations in deep wells, and at the same time, effectively protect the ignition assembly 3 during the process of hoisting the ignition device down into the well or dragging it out of the well. It can also perform real-time temperature and pressure detection on the ignition center point and the surrounding area during the underground ignition process, and protect the structure of the ignition device in real time according to the detected temperature, thereby ensuring the safety and reliability of underground ignition work.

[0078] Furthermore, if the first temperature and pressure parameter continues to be abnormal, the movable rod 31 is moved backward to retract the mounting plate 32 into the inner cavity of the second cylinder 2, and at the same time, cooling protective gas is transported to the cooling cavity D through the second annular cavity C to form a second protective gas film around the ignition nozzle 34.

[0079] When the temperature around the first temperature and pressure detection structure 4 and the second temperature and pressure detection structure 83 is too high, the protective gas film formed by the cooling protective gas can protect the ignition nozzle 34 and the second temperature and pressure detection structure 83, so as to buy enough time for the staff to remove the ignition device from the well and avoid damage to the ignition device.

[0080] The first temperature and pressure detection structure 4 and the second temperature and pressure detection structure 83 are integrated temperature sensors and pressure sensors, which adopt existing products. Their specific structures and usage methods are not described in detail here.

[0081] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0082] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A downhole ignition device for burning oil layers, characterized in that: It includes a first cylinder, a first straightening ring, a second cylinder, an ignition assembly, a first temperature and pressure detection structure, a sandwich shell, a gas delivery mechanism and a control mechanism; The second cylinder is sleeved on the first cylinder so that the front end surface of the first cylinder is located in the inner cavity of the second cylinder, and the first straightening ring is sleeved on the outer wall of the first cylinder so that a preset distance is spaced between the outer wall of the first cylinder and the inner wall of the second cylinder to form a first ring cavity; The ignition assembly comprises a movable rod, a mounting plate, a protective sleeve and an ignition nozzle; The movable rod is inserted into the first cylinder, and the front end surface is connected to the mounting plate; The mounting plate is provided with a plurality of mounting through holes; A protective sleeve is mounted in each of the mounting through holes; An ignition nozzle is arranged in each of the protective sleeves, and the ignition nozzle is connected to an ignition controller outside the well through an ignition cable; A cooling cavity is formed between the inner wall of the front end of the protective sleeve and the outer wall of the front end of the ignition nozzle, and a plurality of axial through grooves are provided on the inner wall of the protective sleeve in contact with the rear end of the ignition nozzle, and the plurality of axial through grooves communicate with the first annular cavity and the cooling cavity; The first temperature and pressure detection structure is arranged on the front end surface of the mounting plate and is electrically connected to the control mechanism; The sandwich shell is cylindrical, with a curved front end, a hollow cavity between the outer wall and the inner wall, and is sleeved on the front end of the second cylinder; The hollow cavity is in communication with the first annular cavity; The outer wall is provided with a plurality of vent holes connecting the hollow cavity and the outside; The mounting plate is clamped at the front end of the inner cavity of the second cylinder and can be extended out of the sandwich shell or retracted into the inner cavity of the second cylinder under the drive of the movable rod; The gas delivery mechanism is in communication with the first annular cavity, and is configured to deliver supporting gas or cooling protection gas to the first annular cavity.

2. The downhole ignition device for burning oil layers according to claim 1 is characterized in that: It also includes a second straightening ring, a protection tube and a peripheral combustion condition detection and adjustment mechanism; The protection tube has an open end and a closed end, and a clamping hole is provided on the closed surface; The second cylinder is inserted into the clamping hole so that the protection tube is sleeved on the second cylinder, and the second straightening ring is sleeved on the outer wall of the second cylinder so that a second annular cavity is formed between the outer wall of the second cylinder and the inner wall of the protection tube; The gas delivery mechanism is in communication with the second annular cavity and is configured to deliver cooling protection gas to the second annular cavity; The peripheral combustion condition detection and adjustment mechanism comprises a plurality of groups, and the plurality of groups of the peripheral combustion condition detection and adjustment mechanism are arranged in a circular array around the central axis of the protection tube; Each group of the peripheral combustion condition detection and adjustment mechanisms includes an expansion arm structure, a temperature and pressure resistant tube, and a second temperature and pressure detection structure; The second temperature and pressure detection structure is arranged on the expansion arm structure and is electrically connected to the control mechanism, and the expansion arm structure can adjust the distance between the second temperature and pressure detection structure and the central axis of the second cylinder; One end of the temperature and pressure resistant tube is communicated with the second annular cavity, and the other end is arranged around the second temperature and pressure detection structure.

3. The downhole ignition device for burning oil layers according to claim 2 is characterized in that: The distances between the multiple expansion arm structures are adjusted to be different.

4. The downhole ignition device for burning oil layers according to claim 2 is characterized in that: The expansion arm structure includes a slide rail, a counterweight, a traction assembly, a first arm, a mounting seat, and a second arm; The slide rail is arranged on the outer wall of the second cylinder, and its extension direction is parallel to the central axis of the second cylinder; The counterweight block is slidably disposed on the slide rail; One end of the traction assembly is connected to the counterweight block, and the other end is connected to the hoisting mechanism outside the well; One end of the first arm is hinged to the counterweight, and the other end is connected to the mounting seat; One end of the second support arm is connected to the mounting seat, and the other end is hinged to the front end of the slide rail.

5. The downhole ignition device for burning oil layers according to claim 1 is characterized in that: The ignition assembly also includes a connecting pipe, a clamping tube and a limiting ring; The rear end of the protective sleeve is connected to a connecting pipe; A fixing tube is sleeved on the rear end of each connecting pipe; The clamping cylinder is clamped in the inner cavity of the second cylinder, and the rear end surface is located in front of the connection point between the hollow cavity and the first annular cavity; One end of the connecting pipe is passed through the fixing tube and then sleeved with a limiting ring, wherein the outer diameter of the limiting ring is greater than the inner diameter of the fixing tube; The axial through groove communicates with the connecting pipe and the cooling cavity.

6. The downhole ignition device for burning oil layers according to claim 1 is characterized in that: Also includes top cap and push rod; One end of the push rod is fixedly connected to the end of the movable rod away from the mounting plate, and the other end is connected to the top cover; The top cover is located outside the rear end surface of the first cylinder; The gas delivery mechanism can be communicated with the first annular cavity through the top cover.

7. The downhole ignition device for burning oil layers according to claim 1 is characterized in that: The ignition assembly also includes a diffusion contact screen; A diffusion contact grid is arranged at the front end of each ignition nozzle.

8. A method for igniting an oil layer downhole, characterized in that: The downhole ignition device for burning oil layers according to any one of claims 1 to 7 comprises: A protective sleeve is clamped in each mounting through hole of the mounting plate, and an ignition nozzle is arranged in each of the protective sleeves. The ignition nozzle is tested for ignition through an ignition cable. If the ignition nozzle is tested for ignition normally, the front end surface of the movable rod is connected to the mounting plate, and the first temperature and pressure detection structure is arranged on the front end surface of the mounting plate and electrically connected to the control mechanism; The second cylinder is sleeved on the first cylinder so that the front end surface of the first cylinder is located in the inner cavity of the second cylinder, and the outer wall of the first cylinder and the inner wall of the second cylinder are spaced at a preset distance to form a first annular cavity; The movable rod is inserted into the first cylinder, the mounting plate is clamped at the front end of the inner cavity of the second cylinder, the interlayer shell is sleeved at the front end of the second cylinder, and the gas delivery mechanism is connected to the first annular cavity. The ignition device is hoisted and lowered, and during the process, cooling protection gas is delivered to the first cavity through the gas delivery mechanism; After the ignition device is hoisted and lowered to a predetermined depth underground, the mounting plate is pushed by a movable rod so that the front end of the ignition nozzle extends out of the sandwich housing; The gas delivery mechanism delivers the combustion-supporting gas into the first annular cavity and ignites the ignition nozzle through the ignition cable; Ignition is successful, and the first temperature and pressure parameters of the area around the ignition nozzle are detected by the first temperature and pressure detection structure. The control mechanism receives the first temperature and pressure parameters transmitted by the first temperature and pressure detection structure to control the gas delivery mechanism to deliver cooling protective gas to the first annular cavity. The cooling protective gas enters the hollow cavity of the sandwich shell and is ejected from the vent to form a first protective gas film around the ignition nozzle.

9. The downhole ignition method for burning oil layers according to claim 8, characterized in that: If the first temperature and pressure parameter continues to be abnormal, the movable rod is moved backward to retract the mounting plate into the inner cavity of the second cylinder, and cooling protective gas is transported to the cooling cavity through the second annular cavity to form a second protective gas film around the ignition nozzle.

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