Shale gas well gas lift dredging method

Abstract

The invention belongs to the technical field of oil and gas well development, and particularly relates to a shale gas well gas lift dredging method. According to the method, the gas lift pressure is obviously reduced to 40-60% through comprehensive means such as foam drainage liquid filling for reducing the gas well accumulated liquid density, short-time annular gas lift, wellhead return pressure reduction for the gas lift, oil jacket pressure balancing for reducing the hydrostatic liquid column height and alternate positive and negative lift, and multiple cooperation is conducted, so that the gas lift pressure is obviously reduced to 40-60%, the gas well recovery production progress can be accelerated, the gas lift effect is improved, and the gas well recovery efficiency is improved. The production recovery cost is reduced. In the process of lifting the deep shale gas well, gas well lifting can be achieved by optimizing gas lifting operation steps on the basis of existing gas lifting equipment, effective gas lifting can be achieved by means of the technical method under the influence of factors such as high temperature and high pressure, shaft corrosion and sand production of the deep shale gas well under different conditions, and the success rate reaches up to 80%.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas well development, and in particular relates to a shale gas well gas lift method. Background Art

[0002] Gas lift is one of the effective means to restore production of gas wells such as deep shale gas flooding or pressure channeling. Pressurized gas (nitrogen / natural gas) is pumped into the wellbore of the gas well through the oil / casing to increase the bottom hole pressure and lift the accumulated liquid in the gas well. When the gas lift reaches the lifting pressure, the injected pressurized gas is lifted from the oil / casing to the ground along with the gas and liquid produced by the gas well itself, thereby achieving the effect of draining and restoring production of pressure channeling / flooded wells.

[0003] At present, the following situations often occur during gas lift drainage:

[0004] The wellbore of deep shale gas wells is greater than 3500m. After flooding, the accumulated liquid exerts a back pressure of 20-35MPa on the bottom of the gas well, making gas lift difficult and unable to effectively drain the liquid and resume production. For gas wells that have been shut down due to flooding, continuous gas lift and drainage are required to effectively resume production.

[0005] Existing gas lift equipment is usually of two levels: 30MPa and 50MPa. When 35MPa gas lift equipment is selected, the purpose of resuming production of flooded wells cannot be achieved for gas wells with a lifting pressure higher than 35MPa; when 50MPa gas lift equipment is selected, the cost of use is 1.5 times higher than that of 35MPa, the economy is poor, and it does not meet the needs of long-term drainage.

[0006] When the lifting pressure is high, it is necessary to use supporting equipment such as higher-grade pressure pipelines, which increases the construction cost and cannot be effectively promoted. In addition, there is a defect that the gas lift equipment has insufficient operating stability, which is easy to cause equipment damage and results in extremely high equipment maintenance costs.

[0007] Based on the above-mentioned practical problems, the cost of resuming production of deep shale gas water-flooded wells / pressure-channeled wells is relatively high. Therefore, how to effectively reduce the lifting pressure of gas wells will be beneficial to reducing the cost of resuming production of deep shale gas water-flooded wells / pressure-channeled wells and improving the efficiency of gas well resumption.

[0008] The existing gas lift technology mainly reduces the starting pressure of gas lift by optimizing the tubing, adding gas lift valves and closed gas lift, which can reduce the gas lift pressure to a certain extent. However, the wellbore of deep shale gas wells exceeds 3500m, resulting in a pressure loss of 30-35MPa, and the underground temperature is above 130℃, accompanied by the return of proppants such as gas well fracturing sand and wellbore corrosion. The adaptability of downhole tools such as gas lift valves and closed gas lift is weak, and the gas lift effect is affected after failure, resulting in limited effect of existing technical solutions on reducing gas lift pressure, and it is easy to cause complex conditions underground, bringing huge maintenance costs. Summary of the invention

[0009] The purpose of the present invention is to provide a low-cost method for reducing the gas lift pressure of deep shale gas wells, aiming to solve the problem of high cost of gas lift resumption in deep shale gas wells due to water-flooded wells and pressure-pushing wells in existing gas lift technology, which requires relatively high gas lift equipment and leads to high cost.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A method for reducing the gas lift pressure of a deep shale gas well at low cost comprises the following steps:

[0012] Step 1: First, inject a foaming agent into the oil pipe and casing of the target gas well respectively, wherein the foaming agent is used to reduce the density of liquid accumulation in the gas well; 液 Indicates that the back pressure caused by the effusion is reduced by △P w Indicates; observe the gas well energy index, when the gas well energy shut-in pressure is restored to greater than 2MPa / d; directly proceed to step 3; if the gas well energy shut-in pressure cannot be restored to 2MPa / d; then proceed to step 2;

[0013] Step 2: Before the formal gas lift operation, according to the casing pressure, perform short-term gas lift to supplement the pressure of the casing annulus to prevent the wellbore fluid from being squeezed back into the formation during gas lift, causing reservoir water lock and reducing the gas well production capacity; the short-term gas lift time shall not exceed 30 minutes;

[0014] Step 3: Perform air lift operation to reduce the wellhead back pressure P yy During the air lifting process, observe the injection pressure (P 注 ), and the lifting condition of the gas well; determine the gas lifting pressure value (P 注 ) is higher than the rated pressure of the gas lift equipment (P 额定 ), when the injection pressure is equal to the rated pressure of the gas lift equipment (P 注 =P 额定 ), the gas well has not yet been opened (P 注 <P jt ), proceed to step 4;

[0015] Step 4: Balance the oil and casing pressure to reduce the height difference of the water column in the oil and casing △H, in order to reduce the back pressure of the static liquid column in the wellbore △P w , continue to observe the gas lift situation of the gas well. When the gas lift pressure value is equal to the highest rated pressure level of the equipment (P 注 =P 额定 ), the gas well has not yet been opened (P 注 <P jt ), proceed to step 5;

[0016] Step 5: Use alternating positive and negative gas lift methods to stimulate the wellbore liquid level to overcome the deadweight of the liquid column and the loss of slippage; observe the lifting condition of the gas well. If the gas well is still not lifted (P 注 <P jt ), return to step 2 and repeat N cycles until the gas well is restored to production.

[0017] The technical solution of the present invention proposes a low-cost method for lifting deep shale gas wells. In this solution, the lifting pressure is reduced by changing the density of the liquid accumulation in the gas well and its liquid accumulation state, which can effectively reduce the requirements for gas lift equipment. According to the calculation formula of the gas lift pressure, the wellhead pressure P yy , Pressure △P caused by effusion w (i.e., pressure loss) and by changing the wellbore fluid state through process switching to reduce the lifting pressure P jt Among them, following the above steps in order can reduce the final lifting pressure P jt .

[0018] Preferably, the calculation formula of the gas lift pressure is:

[0019] P jt =P yy +△P w +P f -P ty ,

[0020] △P w =ρ 液 g△H,

[0021] △H=H y -H t ,

[0022] Among them, P jt is the gas lift pressure, P yy is the wellhead pressure, △P w is the pressure caused by the effusion, g is the acceleration due to gravity, ρ 液 is the density of the accumulated liquid, △H is the liquid level difference between the oil casing and the casing, and H y is the liquid level in the oil pipe, H t is the liquid level in the casing, P f is the fluid friction loss, P ty is the casing pressure.

[0023] Preferably, the foaming agent is selected based on the comprehensive foaming effect between the surface simulated gas well flowback fluid and the foaming agent. The foaming agent is preferably selected in terms of the highest foaming performance, the best foam stability, and the optimal foaming agent concentration, which can further improve the degree of reduction of the gas lift pressure.

[0024] A foaming agent is a surfactant that mainly reduces the interfacial tension at the air-water interface. Its molecular structure is composed of lipophilic groups and hydrophilic groups, forming a so-called "amphiphilic structure" molecule that is both hydrophilic and lipophilic. When a foaming agent is added to water, the hydrophilic groups are inserted into the water phase, while the lipophilic groups are inserted into the oil phase or stand upright in the air, forming a directional arrangement on the interface layer or surface, thereby reducing the interfacial tension or surface tension.

[0025] Further preferably, with respect to the composition of the gas well fluid, a foaming agent of a salt-resistant, oil-resistant or other type is preferred, and the foaming agent is added at a ratio of 0.5% according to the liquid accumulation situation of the gas well.

[0026] Preferably, the foaming agent can be further tested for compatibility with other well fluids to avoid the formation of colloids and other precipitations due to incompatibility of the downhole fluid, which in turn increases the density of the effluent. 液 .

[0027] As a preferred embodiment of the present invention, in step 2, the pressure for annulus pressure replenishment is selected as follows: according to the flow steady flow pressure test results, the bottom hole pressure and liquid accumulation conditions are clarified, and the gas lift pressure should be lower than the bottom hole flow pressure when performing annulus pressure replenishment.

[0028] Further preferably, the time for annulus pressure replenishment is selected as follows: when the casing pressure is less than or equal to 5MPa, short-term gas lift is 1-2h; when the casing pressure is greater than 5MPa and less than or equal to 10MPa, short-term gas lift is 3-4h; when the casing pressure is greater than 10MPa, no short-term gas lift is required.

[0029] As a preferred embodiment of the present invention, in step 3, the specific steps of air lift include: if reverse lift is selected, the oil pipe is connected to the blowout pool process, the opening of the wellhead throttling needle valve is 1 / 4-1 / 2 (adjustable according to the pressure after throttling), the casing air injection valve is opened, and the air lift is started; if forward lift is selected, the casing is connected to the blowout pool process, the opening of the throttling needle valve of the throttling skid is 1 / 4-1 / 2 (adjustable according to the pressure after throttling), the oil pipe air injection valve is opened, and the air lift is started.

[0030] As a preferred technical solution of the present invention, in step 4, balancing the oil and casing pressure specifically includes the following steps: if it is in a positive lift state and in an external transmission process, then when the gas lift equipment is shut down, close the gas tree external transmission gate, open the casing valve, balance the wellbore oil and casing pressure through the oil and casing connecting pipeline, and when the pressure gauge indicates that the pressure is balanced, close the casing valve and resume gas lift; if it is in a reverse lift state, then when the gas lift equipment is shut down, open the tubing production gate to balance the wellbore oil and casing pressure, and when the pressure gauge indicates that the pressure is balanced, close the tubing production gate until gas lift is resumed.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] In the technical solution of the present invention, by comprehensively adopting the methods of injecting bubbles to reduce the density of liquid accumulation in the gas well, reducing the wellhead back pressure by air lift, balancing the oil casing pressure to reduce the height of the static liquid column, etc., the gas lift pressure is significantly reduced to 40-60%. This method can accelerate the progress of gas well resumption of production, improve the gas lift effect, and reduce the cost of resumption of production.

[0033] In the technical solution of the present invention, in the process of lifting deep shale gas wells, the gas well lifting can be achieved by optimizing the gas lifting operation steps on the basis of existing gas lift equipment. In the face of different deep shale gas wells with high temperature and high pressure, wellbore corrosion, sand production and other factors, this technical method can achieve effective gas lifting with a success rate of up to 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flow chart of the method of operation of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] Example 1

[0038] A method for reducing the gas lift pressure of a deep shale gas well at low cost comprises the following steps:

[0039] Step 1: Before the gas lift operation, inject a foaming agent into the tubing and casing respectively to reduce the density of the gas well liquid accumulation and reduce the impact of the liquid column back pressure; observe the gas well energy index, when the gas well energy shut-in pressure is restored to more than 2MPa / d; directly proceed to step 3, when the gas well energy shut-in pressure is restored to no more than 2MPa / d; proceed to step 2; specifically, the selection of the foaming agent is selected by the comprehensive foaming effect between the ground simulated gas well return fluid and the foaming agent; the foaming agent is preferably selected in terms of high foaming performance, good foam stability, and optimal use concentration of the foaming agent, which can further improve the degree of reduction of the gas lift pressure; according to the composition of the gas well fluid, salt-resistant, oil-resistant and other types of foaming agents are preferred, and the amount of foaming agent added is added at a ratio of 0.5% according to the gas well liquid accumulation situation;

[0040] Step 2: Before the formal gas lift operation, according to the size of the casing pressure, the casing annulus is short-term gas lift to supplement the pressure, so as to prevent the wellbore accumulated liquid from being squeezed back into the formation during gas lift, causing reservoir water lock and reducing the gas well production capacity; the pressure selection for annulus pressure supplement: according to the results of the steady flow pressure test, the bottom hole pressure and liquid accumulation conditions are clarified, and the gas lift pressure should be lower than the bottom hole flow pressure when the annulus pressure is supplemented.

[0041] Specifically, the time selection for annulus pressure replenishment is: when the casing pressure is less than 5MPa, short-term gas lift is 1-2h; when the casing pressure is greater than 5MPa and lower than 10MPa, short-term gas lift is 3-4h; when the casing pressure is greater than 10MPa, no short-term gas lift is required.

[0042] Step 3: Perform air lift operation to reduce the wellhead back pressure P yy During the air lifting process, observe the injection pressure (P 注 ), and the lifting condition of the gas well; determine the gas lifting pressure value (P 注 ) is higher than the rated pressure of the gas lift equipment (P 额定 ), when the injection pressure is equal to the rated pressure of the gas lift equipment (P 注 =P 额定 ), the gas well has not yet been opened (P 注 <P jt ), proceed to step 4; in detail, in step 3, the specific steps for air lift include the following: if reverse lift is selected, the oil pipe is connected to the blowout pool process, the wellhead throttling needle valve is opened to 1 / 4-1 / 2, the casing air injection valve is opened, and the air lift is started; if forward lift is selected, the casing is connected to the blowout pool process, the throttling needle valve of the throttling skid is opened to 1 / 4-1 / 2, the oil pipe air injection valve is opened, and the air lift is started.

[0043] Furthermore, the calculation formula of the gas lift pressure is:

[0044] P jt =P yy +△P w +P f -P ty ,

[0045] △P w =ρ 液 g△H,

[0046] △H=H y -H t ,

[0047] Among them, P jt is the gas lift pressure, P yy is the wellhead pressure, △P w is the pressure caused by the effusion, g is the acceleration due to gravity, ρ 液is the density of the accumulated liquid, △H is the liquid level difference between the oil casing and the casing, and H y is the liquid level in the oil pipe, H t is the liquid level in the casing, P f is the fluid friction loss, P ty is the casing pressure. In this scheme, the lifting pressure can be reduced by changing the density of the liquid in the gas well and its state, which can effectively reduce the requirements for gas lift equipment. According to the calculation formula of gas lift pressure, the wellhead pressure P yy , Pressure △P caused by effusion w (i.e., pressure loss) and by changing the wellbore fluid state through process switching to reduce the lifting pressure P jt Among them, following the above steps in order can reduce the final lifting pressure P jt .

[0048] Step 4: Balance the oil and casing pressure to reduce the height difference of the water column in the oil and casing △H, in order to reduce the back pressure of the static liquid column in the wellbore △P w , continue to observe the gas lift situation of the gas well. When the gas lift pressure value is equal to the highest rated pressure level of the equipment (P 注 =P 额定 ), the gas well has not yet been opened (P 注 <P jt ), proceed to step 5;

[0049] Specifically, balancing the casing and oil pressure includes the following steps: if it is in the positive lift state and in the external transmission process, then when the gas lift equipment is shut down, close the external transmission gate of the gas tree, open the casing valve, and balance the wellbore casing and oil pressure through the casing connecting pipeline. When the pressure gauge indicates that the pressure is balanced, close the casing valve and resume gas lift. If it is in the reverse lift state, then when the gas lift equipment is shut down, open the tubing production gate to balance the wellbore casing pressure. When the pressure gauge indicates that the pressure is balanced, close the tubing production gate until gas lift is resumed.

[0050] Step 5: Use alternating positive and negative gas lift methods to stimulate the wellbore liquid level to overcome the deadweight of the liquid column and the loss of slippage; observe the lifting condition of the gas well. If the gas well is still not lifted (P 注 <P jt ), return to step 2 and repeat N cycles until the gas well is restored to production.

[0051] Example 2

[0052] The experimental object of this embodiment is gas well #1. The basic information of gas well #1 is: the vertical depth of the gas well is 3830m, the oil pressure is 2.09MPa, the casing pressure is 18.6MPa, and the production is stopped due to water flooding;

[0053] The steps of reducing the gas lift pressure of gas well #1 at low cost specifically include the following steps:

[0054] Step 1: Take a water sample from gas well #1, conduct a ground simulation experiment of gas well flowback fluid and foaming agent to determine the foaming agent with high foaming performance, good foam stability and optimal foaming concentration, inject 20 kg of foaming agent into the oil pipe and casing respectively to reduce the density of liquid accumulation in the gas well bore; observe the energy index of the gas well, the casing pressure of the wellhead of gas well #1 is greater than 10 MPa, and there is no need to perform short-term pressure replenishment, and directly perform the operation of step 3;

[0055] Step 3, select the gas lift equipment pressure as 30MPa, guide the gas lift process to the air process for gas lift, after 6 hours of gas lift, the oil pressure is 0MPa, and the casing pressure is 27.4MPa, which is close to the rated pressure of the gas lift equipment; it still does not lift; continue with the operation of step 4;

[0056] Step 4: Balance the casing and oil pressure. After balance, the oil / casing pressure is 18.8 MPa. After 6 hours of gas lift, the oil pressure is 1.5 MPa and the casing pressure is 26.3 MPa. A large amount of liquid is returned and discharged from the wellhead. After accumulatively discharging 27 cubic meters of liquid, the well is lifted and restored to production. The instantaneous liquid production is 93 cubic meters / day and the instantaneous gas production is 121,000 cubic meters / day.

[0057] Step 5: Successfully resume production and bring gas well #1 back into production.

[0058] Example 3

[0059] The experimental object of this embodiment is gas well #2; the basic information of gas well #2 is: the vertical depth of the gas well is 3650m, the oil pressure is 1.5MPa, the casing pressure is 4.5MPa, the gas well cannot produce liquid, the oil-casing pressure difference continues to expand, and the flooding trend is determined;

[0060] The steps of reducing the gas lift pressure of gas well #2 at low cost specifically include the following steps:

[0061] Step 1: Take a water sample from gas well #2, conduct a ground simulation experiment of gas well flowback fluid and foaming agent, determine the foaming agent with high foaming performance, good foam stability and optimal foaming agent concentration, inject 10 kg of foaming agent into the oil pipe and casing respectively to reduce the density of liquid accumulation in the gas well bore; observe the gas well energy index,

[0062] Step 2: As the casing pressure at the wellhead is less than 5MPa, short-term pressure replenishment is performed for 2 hours, the oil pressure is 3.6MPa, and the casing pressure is 7.8MPa;

[0063] Step 3: Select the gas lift equipment pressure as 30MPa, and guide the gas lift process to the air process for gas lift (oil pressure 0MPa, casing pressure 6.5MPa). After 5h of gas lift, a large amount of liquid returns to the wellhead (oil pressure 1.2MPa, casing pressure 10.5), with an instantaneous gas production of 52,000 cubic meters / day and an instantaneous liquid production of 25 cubic meters / day.

[0064] Step 4: Successfully resume production and bring gas well #2 back into production.

[0065] Example 4

[0066] The experimental object of this embodiment is gas well #3. The basic information of gas well #3 is: the vertical depth of the gas well is 3710m, the oil pressure is 1.0MPa, the casing pressure is 24.6MPa, and the gas well is flooded and shut down.

[0067] Step 1: Take a water sample from gas well #1, conduct a ground simulation experiment of gas well flowback fluid and foaming agent to determine the foaming agent with high foaming performance, good foam stability and optimal foaming concentration, inject 20 kg of foaming agent into the oil pipe and casing respectively to reduce the density of liquid accumulation in the gas well bore; observe the energy index of the gas well, the casing pressure of the wellhead of gas well #1 is greater than 10 MPa, and there is no need to perform short-term pressure replenishment, and directly perform the operation of step 3;

[0068] Step 3: Select the gas lift equipment pressure as 30MPa, and guide the gas lift process to the air process for gas lift. After 6 hours of gas lift, the oil pressure is 0MPa and the casing pressure is 26.7MPa, which is close to the rated pressure of the gas lift equipment. The lifting is still not successful. Continue with the operation of step 4.

[0069] Step 4: Balance the casing and oil pressure. After balance, the oil / casing pressure is 16.4 MPa. After 6 hours of gas lift, the oil pressure is 0 MPa, the casing pressure is 27.4 MPa, and there is intermittent liquid return at the wellhead.

[0070] Step 5, switch the process to alternate forward and reverse gas lift, alternate gas lift twice, the wellhead oil pressure is 1.2MPa, the casing pressure is 26.5MPa, and the wellhead continues to return liquid. After 1 hour, the wellhead oil pressure is 12.8MPa, the casing pressure is 19.4MPa, the instantaneous gas production is 98,000 cubic meters / day, the instantaneous liquid production is 158 cubic meters / day, and the cumulative liquid discharge is 40 cubic meters; the production is successfully resumed and the production process is introduced.

[0071] In the technical solution of the present invention, by comprehensively adopting the methods of injecting bubbles to reduce the density of liquid accumulation in the gas well, reducing the wellhead back pressure by air lift, balancing the oil casing pressure to reduce the height of the static liquid column, etc., the gas lift pressure is significantly reduced to 40-60%. This method can accelerate the progress of gas well resumption of production, improve the gas lift effect, and reduce the cost of resumption of production.

[0072] In the technical solution of the present invention, in the process of lifting deep shale gas wells, the gas well lifting can be achieved by optimizing the gas lifting operation steps on the basis of existing gas lift equipment. In the face of different deep shale gas wells with high temperature and high pressure, wellbore corrosion, sand production and other factors, this technical method can achieve effective gas lifting with a success rate of up to 80%.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A shale gas well gas lift method, characterized in that: The steps include: Step 1: First, a foaming agent is injected into the oil pipe and casing of the target gas well respectively, wherein the foaming agent is used to reduce the density of liquid accumulation in the gas well; the energy index of the gas well is observed, and when the energy shut-in pressure of the gas well is restored to greater than 2MPa / d, step 3 is performed; if the energy shut-in pressure of the gas well cannot be restored to 2MPa / d, step 2 is performed; Step 2: Perform short-term gas lift on the casing annulus to replenish the bottom hole pressure, and then proceed to step 3; Step 3, perform air lift operation. During the air lift process, observe the gas lift pressure value of the gas lift equipment and the lifting condition of the gas well; determine whether the gas lift pressure value is higher than the highest pressure level of the equipment. When the gas lift pressure value exceeds the highest pressure level of the equipment and the gas well has not been lifted, proceed to step 4; Step 4: Balance the oil-casing pressure to reduce the height difference of the water column in the oil-casing and the static liquid column back pressure in the wellbore, and continue to observe the lifting of the gas well and the gas lift pressure value; when the gas lift pressure value approaches or reaches the highest level of the equipment rated pressure level, and the gas well is still not lifted, proceed to step 5; Step 5: Use alternating positive and negative gas lift methods to agitate the wellbore liquid level and overcome the deadweight of the liquid column and slippage losses; observe the lifting status of the gas well. If the gas well is still not lifted, return to step 2.

2. A shale gas well gas lift method according to claim 1, characterized in that: The foaming agent is selected based on the foaming effect between the surface simulated gas well flowback fluid and the foaming agent, and the foaming agent with the best effect is selected.

3. A shale gas well gas lift method according to claim 2, characterized in that: The foaming agent includes salt-resistant and oil-resistant foaming agents.

4. A shale gas well gas lift method according to claim 1, characterized in that: In step 2, the casing annulus is gas lifted, and the gas lift pressure is selected as follows: according to the flow steady pressure test results, the bottom hole pressure and liquid accumulation conditions are clarified, and the gas lift pressure should be lower than the bottom hole flow pressure when the annulus is pressurized.

5. A shale gas well gas lift method according to claim 4, characterized in that: In step 2, the time for annulus pressure replenishment is selected as follows: when the casing pressure is less than or equal to 5MPa, short-term gas lift is performed for 1-2 hours; when the casing pressure is greater than 5MPa and less than or equal to 10MPa, short-term gas lift is performed for 3-4 hours; when the casing pressure is greater than 10MPa, no short-term gas lift is required.

6. A shale gas well gas lift method according to claim 4, characterized in that: In step 2, short-term gas lift is divided according to the gas well pressure level. When the wellhead pressure of the gas well is greater than 5MPa, the short-term gas lift time is 1-2h. When the wellhead pressure of the gas lift does not exceed 5MPa, the short-term gas lift time is 3-4h.

7. A shale gas well gas lift method according to claim 1, characterized in that: In step 3, the air lift specifically includes the following steps: if reverse lift is selected, the oil pipe is connected to the blowout pool process, the opening of the wellhead throttle needle valve is 1 / 4-1 / 2, the casing gas injection valve is opened, and the gas lift is started; If positive lift is selected, the casing is connected to the blowout pool process, the throttling needle valve of the throttling skid is opened to 1 / 4-1 / 2, and the opening is adjusted according to the pressure after throttling), the oil pipe air injection valve is opened, and gas lift is started.

8. A shale gas well gas lift method according to claim 1, characterized in that: In step 4, balancing the oil and casing pressure specifically includes the following steps: if it is in the positive lift state and in the external transmission process, then when the gas lift equipment is shut down, close the external transmission gate of the gas tree, open the casing valve, balance the wellbore oil and casing pressure through the oil and casing connecting pipeline, and when the pressure gauge indicates that the pressure is balanced, close the casing valve and resume gas lift; If it is in the reverse lift state, when the gas lift equipment is shut down, open the tubing production gate to balance the wellbore casing pressure. When the pressure gauge indicates that the pressure is balanced, close the tubing production gate until gas lift is restored.

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