Horizontal well air injection hot miscible-phase huff and puff oil extraction method and system

Abstract

The invention belongs to the technical field of air injection development, and discloses a horizontal well air injection hot mixed-phase huff and puff oil extraction method and system, and the method comprises the steps: injecting a catalyst slug, a foaming agent slug and air into a horizontal well in a target oil reservoir for oxygen consumption starting; injecting air into the horizontal well to perform oxidation reaction with crude oil in the reservoir to form a hot air cavity, so that the formation energy is supplemented by the hot mixed phase to form micro cracks in the pore structure of the reservoir; when the air injected into the horizontal well reaches the set amount, nitrogen with the set amount is injected into the horizontal well, water injection is replaced, and the air in the horizontal well is displaced to enter the deep part of the stratum, so that the temperature of a shaft is lower than a set value; soaking the horizontal well to form a gas cap; and opening the well for production after the soaking is finished. The method is suitable for conventional medium-high permeability old oil fields developed by horizontal wells and low-permeability tight oil, shale oil and other tight reservoirs transformed by volume fracturing, and the scheme is easy and effective to implement. According to the method, the single well yield and recovery efficiency of the depleted horizontal well are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of air injection development, and in particular relates to a method and system for producing oil by injecting hot mixed phase of air into a horizontal well. Background Art

[0002] Air injection thermal miscibility technology refers to the technology of injecting catalytic oxygen-consuming agents and air into the formation through injection wells to preheat the oil layer, forming a medium-high temperature thermal oxidation state of the formation crude oil and air, and achieving phase change thermal miscibility with the liquid crude oil by the medium-high temperature flue gas produced by thermal oxidation, eliminating interfacial tension, overcoming capillary force effects, effectively mobilizing the crude oil in the matrix pores, and greatly improving the recovery rate.

[0003] Horizontal wells have become an effective means of large-scale development of low-permeability and tight reservoirs, and an important technology for improving the recovery rate of medium- and high-permeability old oil fields. The application scale of horizontal wells has expanded rapidly in recent years. However, horizontal wells have a fast oil production rate and a rapid decline in production. It is difficult to effectively replenish energy in the later stage of development. Improving the production and recovery rate of a single well faces major technical challenges. Gas injection replenishment is an important means of improving the recovery rate. The injected gas medium usually includes natural gas, CO2, nitrogen, etc. However, due to the high cost and transportation cost of the injected gas medium, the difficulty of on-site operation technology, and the prominent crossflow problem, the large-scale application of conventional gas injection development is limited.

[0004] Air injection hot miscible technology is to continuously inject air into the oil layer to produce high-temperature thermal oxidation. The mixed pressure of the generated mixed-phase gas is greatly reduced under high-temperature conditions, and hot miscibility with liquid crude oil is achieved, and the oil recovery efficiency reaches more than 90%. The injection medium air in air hot miscible development has a wide range of sources and no medium cost, which avoids the problem of high medium cost in conventional gas injection development and difficulty in large-scale application. The on-site operation method is simple, with low operating cost, high development efficiency and wide application range. Air injection hot miscible drive technology has been successfully tested on the field and achieved important technical breakthroughs.

[0005] Gas injection and huff-and-puff in horizontal wells is one of the important means to improve oil recovery. The existing gas injection and huff-and-puff methods have small gas injection scale, short well shut-down time, prominent gas crossflow problems after well production, and short effective huff-and-puff time. Summary of the invention

[0006] In view of the above problems, the present invention provides a method and system for oil production by injecting hot mixed phase of air into a horizontal well, which adopts the following technical solutions:

[0007] A method for producing oil by injecting air into a horizontal well and performing hot mixed phase huff and puff, comprising the following steps: injecting a catalyst slug, a foaming agent slug and air into a horizontal well in a target oil reservoir for oxygen consumption startup; injecting air into the horizontal well for oxidation reaction with reservoir crude oil to form a hot gas cavity, so as to achieve hot mixed phase replenishment of formation energy and form microcracks in the reservoir pore structure; when the air injected into the horizontal well reaches a set amount, injecting a set amount of nitrogen into the horizontal well, and replacing water injection, so as to displace the air in the horizontal well into the deep formation and make the wellbore temperature lower than the set value; soaking the horizontal well, monitoring the bottom hole temperature and pressure of the horizontal well, and ending the soaking when the bottom hole temperature and pressure of the horizontal well are stable to form a gas cap; and starting the well for production after soaking is completed.

[0008] Further, injecting catalyst and air into the horizontal well in the target oil reservoir for oxygen consumption start-up includes the following steps:

[0009] A catalyst plug is injected into the horizontal well in the target oil reservoir, followed by a foam plug at a set temperature, followed by air injection into the horizontal well at a set speed, and the oxidation reaction at the formation temperature is used to release heat to complete the oxygen consumption startup.

[0010] Further, air is injected into the horizontal well to react with the reservoir crude oil for oxidation, thereby forming a hot gas cavity, and realizing hot mixed phase replenishment of formation energy to form micro-cracks in the reservoir pore structure, including the following steps:

[0011] Inject a set amount of air into the horizontal well within a set time, so that the reservoir crude oil and air in the horizontal well reach a stable medium-high temperature thermal oxidation state, forming a hot gas cavity, and realizing hot mixed phase supplementation of formation energy to transform the reservoir pore structure and form micro-cracks.

[0012] Furthermore, the catalyst content in the catalyst slug is 1-5% by weight, the catalyst injection temperature is 0-40° C., and the catalyst injection amount is (1-1.5)×1 m 3 , where l is the length of the horizontal well.

[0013] Furthermore, the volume of the injected foaming agent is (0.5-1)×1 m 3 , where l is the length of the horizontal well.

[0014] Furthermore, when the horizontal well length is 400-1000 m, the gas injection rate is 10-50×10 4 Nm 3 / d, the air injection time is 60 to 90 days, and the cumulative air injection volume is 600 to 2000×10 4 Nm 3 .

[0015] Furthermore, the amount of nitrogen injected is (50-100)×lNm 3, the replacement water injection volume is (1~1.5)×lm 3 , where l is the horizontal well length.

[0016] Furthermore, the well-keeping time is 180 to 240 days.

[0017] Furthermore, the target reservoir needs to meet the following conditions: reservoir pressure > 15MPa, oil layer thickness > 10m, horizontal well located in the lower middle part of the oil layer, and residual oil saturation at the bottom of the well > 30%.

[0018] Furthermore, the following steps are included: real-time monitoring of the horizontal well bottom temperature, produced gas components and production pressure difference during the well production process.

[0019] The present invention also provides a horizontal well air injection hot mixed phase huff and puff oil production system, comprising:

[0020] A gas-liquid injection unit is used to inject catalyst slugs, foaming agent slugs and air into horizontal wells in the target reservoir for oxygen consumption startup;

[0021] The gas injection unit is used to inject air into the horizontal well to react with the reservoir crude oil to form a hot gas cavity, so as to achieve hot mixed phase to supplement the formation energy and form micro-cracks in the reservoir pore structure;

[0022] The displacement unit is used to inject a set amount of nitrogen into the horizontal well when the air injected into the horizontal well reaches a set amount, and then replace the water injection to displace the air in the horizontal well into the deep formation so that the wellbore temperature is lower than the set value;

[0023] Well soaking unit, used to soak the horizontal well and monitor the bottom temperature and pressure of the horizontal well. When the bottom temperature and pressure of the horizontal well are stable, well soaking is terminated to form a gas cap.

[0024] The oil production unit starts production after the well is shut down.

[0025] Furthermore, the gas-liquid injection unit is specifically used for:

[0026] A catalyst plug is injected into the horizontal well in the target oil reservoir, followed by the injection of a foam agent at a set temperature, followed by the injection of air and catalyst mixture into the horizontal well at a set speed, and the oxidation reaction is released using the formation temperature to complete the oxygen consumption startup.

[0027] Furthermore, the gas injection unit is specifically used for:

[0028] Inject a set amount of air into the horizontal well within a set time, so that the reservoir crude oil and air in the horizontal well reach a stable medium-high temperature thermal oxidation state, forming a hot gas cavity, and realizing hot mixed phase supplementation of formation energy to transform the reservoir pore structure and form micro-cracks.

[0029] Beneficial effects of the present invention:

[0030] 1. The present invention is applicable to conventional medium- and high-permeability old oil fields developed by horizontal wells, low-permeability, tight oil and shale oil reservoirs transformed by volume fracturing, and the implementation of the scheme is simple and effective.

[0031] 2. The present invention greatly supplements formation energy and forms an artificial gas cap by far exceeding the conventional gas injection scale and well-keeping time, thereby achieving resaturation of crude oil near the wellbore area and significantly improving the single well production and recovery rate of the exhausted horizontal well.

[0032] 3. The present invention greatly reduces the miscible pressure through thermal effect, realizes thermal miscibility, and increases the oil displacement efficiency from 40% to more than 90%. At the same time, a hot gas cavity is formed within a certain range near the wellbore, and the high temperature transforms the pore structure of the reservoir near the wellbore to form micro-cracks, thereby increasing the seepage capacity by 10 to 20 times.

[0033] 4. The present invention has a simple injection-production relationship, low cost investment, and simple operation. It fully utilizes the original horizontal production wells and does not require large-scale thermal completion. The injection medium is air, which is simple and easy to obtain and does not require medium costs. It also overcomes the problems of corrosion, transportation, and complex injection processes in conventional gas injection development.

[0034] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic flow chart of a method for producing oil by hot mixed phase huff and puff of air injection into a horizontal well according to an embodiment of the present invention is shown;

[0037] Figure 2 A structural schematic diagram of a horizontal well air injection hot mixed phase huff and puff oil production system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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.

[0039] It should be noted that the terms "first", "second", etc. in this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so as to describe the embodiments of the present application described here.

[0040] The present invention provides a method and system for oil production by hot mixed phase huff and puff of air injected into a horizontal well. The method comprises the following steps: by sequentially injecting a catalyst and a large amount of air into a horizontal well located in the middle and lower part of an oil layer, efficient oxygen consumption startup is completed to realize hot miscibility, and the oil displacement efficiency is increased to more than 90%. The scale of air injection far exceeds that of a conventional gas injection development method, and the formation energy is greatly supplemented to increase the formation pressure. A hot gas cavity is formed in a near-wellbore zone, and the pore structure of the reservoir in the near-wellbore zone is reformed by high temperature to form microcracks, and the seepage capacity is improved by 10 to 20 times. The well shut-in time far exceeds that of conventional gas injection huff and puff development, and gravity differentiation is fully utilized to form an artificial gas cap, so that crude oil in the near-wellbore zone is re-saturated, gas channeling problems in the recovery process are effectively suppressed, and the expansion energy of the gas cap is utilized to extend the recovery production time, so that the production and recovery rate of conventional medium- and high-permeability old oil fields developed by horizontal wells, and low-permeability, tight oil, shale oil and other tight reservoirs reformed by volume fracturing are greatly improved.

[0041] like Figure 1 As shown, a method for producing oil by injecting hot mixed phase of air into a horizontal well comprises the following steps:

[0042] S1. Determine the target reservoir. For example, select a light reservoir that can be developed by air injection, with reservoir pressure > 15MPa, oil layer thickness > 10m, horizontal wells located in the middle and lower part of the oil layer, and the remaining oil saturation at the bottom of the well > 30%.

[0043] S2. High-efficiency oxygen consumption start-up step: inject catalyst and air into the horizontal wells in the target reservoir for oxygen consumption start-up, as follows:

[0044] A catalyst plug is injected into the horizontal well in the target oil reservoir, followed by a foam plug at a set temperature, followed by air injection into the horizontal well at a set speed, and the oxidation reaction at the formation temperature is used to release heat to complete the oxygen consumption startup.

[0045] For example, the catalyst content in the catalyst plug injected into the horizontal well is 1-5% by weight, the catalyst plug injection temperature is 0-40°C, and the catalyst plug injection volume is (1-1.5)×1 m 3 , where l is the length of the horizontal well.

[0046] For example, the volume of the foaming agent injected is (0.5~1)×1 m 3 Clean the wellbore to ensure that there is no residual oil on the wall, and the catalyst enters the oil layer and comes into contact with the saturated crude oil in the formation.

[0047] For example, instead of high-speed air injection, the air is mixed with the injected catalyst, and the formation temperature (>50°C) is used to generate oxidation heat to complete efficient oxygen consumption startup.

[0048] In this step, the catalyst and a large amount of air are sequentially injected into the horizontal wells located in the middle and lower part of the oil layer to complete the efficient oxygen consumption startup and realize hot mixing.

[0049] S3, air injection to create hot gas cavity step: inject air into the horizontal well to react with the reservoir crude oil for oxidation, forming a hot gas cavity, achieving thermal mixing to supplement the formation energy and form micro-cracks in the reservoir pore structure, as follows:

[0050] Within the set time, a set amount of air is injected into the horizontal well, so that the reservoir crude oil and air in the horizontal well reach a stable medium-high temperature thermal oxidation state, forming a hot gas cavity, achieving thermal miscibility, and increasing the oil recovery efficiency to more than 90%, greatly supplementing the formation energy to transform the reservoir pore structure to form micro-cracks.

[0051] For example, when continuously injecting large amounts of air into a horizontal well, the air injection speed and volume vary according to the length of the horizontal well. When the horizontal well length is 400 to 1000 m, the air injection speed is 10 to 50 × 10 4 Nm 3 / d, continuous air injection for 60 to 90 days, cumulative air injection of 600 to 2000×10 4 Nm 3 The reservoir crude oil and air reach a stable medium-high temperature thermal oxidation state, achieving thermal miscibility, forming a hot gas cavity within about 5m near the wellbore, and high temperature transforms the reservoir pore structure near the wellbore to form micro-cracks, increasing the seepage capacity by 10 to 20 times.

[0052] S4, nitrogen and water plugging to prevent backflow: When the air injected into the horizontal well reaches a set amount, a set amount of nitrogen is injected into the horizontal well, and water injection is substituted to displace the air in the horizontal well into the deep formation so that the wellbore temperature is lower than the set value.

[0053] For example, when the designed air injection volume is reached in the horizontal well, the continuous nitrogen injection volume is (50-100)×lNm 3, the replacement water injection volume is (1~1.5)×lm 3 , where l is the length of the horizontal well, which displaces air into the deep formation and reduces the wellbore temperature (ensuring that the wellbore temperature is below 200°C) to prevent secondary heat generation due to air reflux and cause damage to the wellbore.

[0054] S5, well soaking to form an artificial gas cap: soak the horizontal well and monitor the bottom temperature and pressure of the horizontal well. When the bottom temperature and pressure of the horizontal well are stable, the well soaking is terminated to form a gas cap.

[0055] For example, a temperature and pressure monitoring system is installed at the bottom of the well to continuously monitor the changes in bottom hole temperature and pressure. When the bottom hole temperature is lower than 150°C and the temperature and pressure reduction rate tends to be stable, the well is shut down. Affected by the physical properties of the reservoir and fluid, the gas-liquid gravity differentiation rate is different under different reservoir conditions, and the gas cap formation and crude oil resaturation rates near the wellbore are different. The well shut-in time changes accordingly and is extended as the reservoir and fluid properties deteriorate. The estimated well shut-in time is 180 to 240 days.

[0056] In this step, the gas injection volume and well-keeping time far exceed those of conventional gas injection development methods, which greatly supplements the formation energy, forms an artificial gas cap, and achieves re-saturation of crude oil in the near-wellbore area.

[0057] S6. Well opening and recovery production steps: After the well is shut down, the well is opened for production. During the well opening and production process, the horizontal well bottom temperature, output gas composition and production pressure difference are monitored in real time.

[0058] For example, after the well is shut down, the well is opened for production. During the production process, the bottom hole temperature is monitored in real time. When the temperature exceeds the set temperature (200°C), water is injected into the horizontal well to cool it down and prevent damage to the wellbore.

[0059] For example, real-time monitoring of the oxygen and hydrogen sulfide content in the output gas can ensure safe production.

[0060] For example, control the reasonable production pressure difference, adjust the production speed, and maintain stable gas cap drive production.

[0061] This step finds the best time to open the well for production. The well is opened for production when the bottom hole temperature is lower than 150°C and the temperature and pressure reduction rates tend to be stable; the production rate is controlled reasonably, the gas cap expansion energy is effectively utilized, gas channeling is suppressed, and the production time is extended; the production temperature and pressure changes and the output gas components are monitored in real time to ensure safe production.

[0062] S7. When the production of the horizontal well is exhausted, the next round of air injection hot mixed phase huff and puff is carried out, and the same steps as S2 to S6 are repeated.

[0063] Based on the above horizontal well air injection hot miscible huff and puff oil production method, Figure 2As shown, the present invention also provides a horizontal well air injection hot mixed phase huff and puff oil production system, including a gas-liquid injection unit, a gas injection unit, a displacement unit, a well shut-in unit and an oil production unit.

[0064] Among them, the gas-liquid injection unit is used to inject catalyst plugs, foam plugs and air into the horizontal wells in the target oil reservoir for oxygen consumption startup; the gas injection unit is used to inject air into the horizontal well to react with the reservoir crude oil for oxidation to form a hot gas cavity, realize thermal mixing to supplement the formation energy and form micro-cracks in the reservoir pore structure; the displacement unit is used to inject a set amount of nitrogen into the horizontal well when the air injected into the horizontal well reaches a set amount, and then replace the water injection to drive the air in the horizontal well into the deep formation to make the wellbore temperature lower than the set value; the well-holding unit is used to hold the horizontal well and monitor the bottom hole temperature and pressure of the horizontal well. When the bottom hole temperature and pressure of the horizontal well are stable, the well-holding is terminated to form a gas cap; the oil production unit is used to start the well for production after the well-holding is completed.

[0065] The horizontal well air injection hot miscible phase huff and puff oil production method and system of the present invention applies air hot miscible phase technology to horizontal well huff and puff development, and is suitable for conventional medium and high permeability old oil fields developed by horizontal wells, as well as for the development of low permeability, tight oil and shale oil and other tight reservoirs transformed by volume fracturing, and can greatly improve the production and recovery rate of depleted horizontal wells.

[0066] The present invention has a simple injection-production relationship, low cost investment, and simple operation. It fully utilizes the original horizontal production wells and does not require large-scale thermal completion. The injection medium is air, which is simple and easy to obtain and does not require medium costs. It also overcomes the problems of corrosion, transportation, and complex injection processes in conventional gas injection development.

[0067] For example, a theoretical model is established in combination with the actual situation of a certain oil field reservoir block. The average burial depth of the reservoir is 3000m, the effective oil layer thickness is 20m, the current gas injection pressure is about 23MPa, the formation temperature is 111℃, the permeability is 5.85mD, and the oil saturation is 55%. Horizontal well huff and puff development is adopted, the horizontal well length is 400m, and the horizontal section is located 5m above the bottom of the oil layer. Based on the horizontal well air injection hot miscible huff and puff oil production method and system of the present invention, the oil production adopts the following steps and parameters:

[0068] 1. Inject 400m into the formation 3 Catalytic combustion aid (wt1%) segment plug, injection temperature 0~40℃, injection speed 30m 3 / h, maximum injection pressure 30MPa.

[0069] 2. Replace injection 400m 3 Thermal foaming agent ensures that the catalytic combustion aid enters the oil layer and comes into contact with the saturated crude oil in the formation.

[0070] 3. Continue to inject air at a speed of 10×104Nm 3 / d, the formation temperature is 111℃, the crude oil in the formation achieves efficient oxygen consumption startup and enters a stable high-temperature hot mixed state, and the predicted temperature is 450℃.

[0071] 4. Cumulative injection 600×104Nm 3 After air, nitrogen gas 2×104Nm 3 , water injection 400m 3 .

[0072] 5. Shut down the well and keep it shut down for 180 days.

[0073] 6. Start production and control the liquid production speed to 100m 3 / d, with minimum bottom hole pressure of 15MPa for continuous production.

[0074] The present invention consumes air to efficiently generate mixed-phase gas inside the oil reservoir, realizes air injection thermal miscibility, and improves the oil recovery efficiency from 40% of conventional gas drive / water drive to more than 90%. At the same time, large-scale air injection forms a hot gas cavity within 5m of the near-wellbore area, and high-temperature transformation of the reservoir pore structure in the near-wellbore area forms micro-cracks, thereby increasing the seepage capacity by 10 to 20 times.

[0075] The present invention breaks the limitations of conventional gas injection huff and puff development, such as small gas injection scale, difficulty in significantly replenishing energy, short well blocking time, and prominent problems of recovered gas breakthrough, and gives full play to the gas suction capacity of horizontal wells. By injecting a large volume and high speed of gas that far exceeds the conventional gas injection development method, the formation energy is significantly replenished, and the production and recovery rate of conventional medium and high permeability old oil fields developed by horizontal wells, and low permeability, tight oil and shale oil and other tight reservoirs transformed by volume fracturing are greatly improved.

[0076] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing oil by injecting hot mixed air into a horizontal well, characterized in that: The following steps are involved: Injecting catalyst slugs, foam slugs and air into horizontal wells in target reservoirs for oxygen consumption start-up; Inject air into the horizontal well to react with the reservoir crude oil for oxidation, forming a hot gas cavity, achieving thermal mixing to supplement the formation energy and form micro-cracks in the reservoir pore structure; When the air injected into the horizontal well reaches the set amount, a set amount of nitrogen is injected into the horizontal well, and water injection is then carried out to displace the air in the horizontal well into the deep formation so that the wellbore temperature is lower than the set value; The horizontal well is soaked and the bottom temperature and pressure of the horizontal well are monitored. When the bottom temperature and pressure of the horizontal well are stable, the soaking is terminated to form a gas cap. After the well is soaked, the well is opened for production.

2. The horizontal well air injection hot miscible huff and puff oil production method according to claim 1, characterized in that: Injecting catalyst and air into a horizontal well in a target reservoir for oxygen consumption start-up includes the following steps: A catalyst plug is injected into the horizontal well in the target oil reservoir, followed by a foam plug at a set temperature, followed by air injection into the horizontal well at a set speed, and the oxidation reaction at the formation temperature is used to release heat to complete the oxygen consumption startup.

3. The horizontal well air injection hot miscible huff and puff oil production method according to claim 1, characterized in that: Injecting air into the horizontal well to react with the reservoir crude oil for oxidation to form a hot gas cavity, achieve hot mixed phase to supplement the formation energy and form micro cracks in the reservoir pore structure, including the following steps: Inject a set amount of air into the horizontal well within a set time, so that the reservoir crude oil and air in the horizontal well reach a stable medium-high temperature thermal oxidation state, forming a hot gas cavity, and realizing hot mixed phase supplementation of formation energy to transform the reservoir pore structure and form micro-cracks.

4. The horizontal well air injection hot miscible huff and puff oil production method according to claim 2, characterized in that: The catalyst content in the catalyst slug is 1-5% by weight, the catalyst injection temperature is 0-40°C, and the catalyst injection amount is (1-1.5)×lm 3 , where l is the length of the horizontal well.

5. The horizontal well air injection hot miscible huff and puff oil production method according to claim 2, characterized in that: The volume of the injected foam is (0.5~1)×lm 3 , where l is the length of the horizontal well.

6. The horizontal well air injection hot miscible huff and puff oil production method according to claim 3, characterized in that: When the horizontal well length is 400-1000 m, the gas injection rate is 10-50×10 4 Nm 3 / d, the air injection time is 60 to 90 days, and the cumulative air injection volume is 600 to 2000×10 4 Nm 3 .

7. The horizontal well air injection hot miscible huff and puff oil production method according to claim 1, characterized in that: The amount of nitrogen injected is (50~100)×lNm 3 , the replacement water injection volume is (1~1.5)×lm 3 , where l is the horizontal well length.

8. The horizontal well air injection hot miscible huff and puff oil production method according to claim 1, characterized in that: The well soaking time is 180 to 240 days.

9. The method for oil production by hot mixed phase huff and puff air injection in horizontal wells according to any one of claims 1 to 8, characterized in that: The target reservoir must meet the following conditions: reservoir pressure > 15MPa, oil layer thickness > 10m, horizontal well located in the middle and lower part of the oil layer, and the residual oil saturation at the bottom of the well > 30%.

10. The method for oil production by hot mixed phase huff and puff air injection in horizontal wells according to any one of claims 1 to 8, characterized in that: The following steps are also included: During the well opening and production process, the bottom hole temperature, produced gas composition and production pressure difference of the horizontal well are monitored in real time.

11. A horizontal well air injection hot miscible phase huff and puff oil production system, characterized in that: include: A gas-liquid injection unit is used to inject catalyst slugs, foaming agent slugs and air into horizontal wells in the target reservoir for oxygen consumption startup; The gas injection unit is used to inject air into the horizontal well to react with the reservoir crude oil to form a hot gas cavity, so as to achieve hot mixed phase to supplement the formation energy and form micro-cracks in the reservoir pore structure; The displacement unit is used to inject a set amount of nitrogen into the horizontal well when the air injected into the horizontal well reaches a set amount, and then replace the water injection to displace the air in the horizontal well into the deep formation so that the wellbore temperature is lower than the set value; Well soaking unit, used to soak the horizontal well and monitor the bottom temperature and pressure of the horizontal well. When the bottom temperature and pressure of the horizontal well are stable, well soaking is terminated to form a gas cap. The oil production unit starts production after the well is shut down.

12. The horizontal well air injection hot miscible phase huff and puff oil production system according to claim 11, characterized in that: The gas-liquid injection unit is specifically used for: A catalyst plug is injected into the horizontal well in the target oil reservoir, followed by the injection of a foam agent at a set temperature, followed by the injection of air and catalyst mixture into the horizontal well at a set speed, and the oxidation reaction is released using the formation temperature to complete the oxygen consumption startup.

13. The horizontal well air injection hot miscible phase huff and puff oil production system according to claim 11, characterized in that: The gas injection unit is specifically used for: Inject a set amount of air into the horizontal well within a set time, so that the reservoir crude oil and air in the horizontal well reach a stable medium-high temperature thermal oxidation state, forming a hot gas cavity, and realizing hot mixed phase supplementation of formation energy to transform the reservoir pore structure and form micro-cracks.

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