Method for combined drainage and gas recovery by using drainage and recovery integrated pipe column

Abstract

The invention relates to the technical field of shale gas production, in particular to a method for composite drainage and gas production by using a drainage and production integrated pipe column, which comprises the following steps: connecting the drainage and production integrated pipe column with a wellhead gas production tree, and descending the drainage and production integrated pipe column into a well; a sensor is used for detecting temperature and pressure data of the bottom of the oil pipe and transmitting the data to a ground control cabinet; the ground control cabinet converts sensor data into the submergence degree of the mechanical pump, when the submergence degree is not lower than a first preset threshold value, the mechanical pump is started, an air inlet channel switch is closed, and liquid discharging operation is started; when the submergence degree is smaller than a second preset threshold value, the mechanical pump is stopped, a gas inlet channel switch is turned on, and gas production operation is started; and the ground control cabinet circularly switches liquid drainage or gas production operation according to the change of the submergence degree. The method can effectively reduce slippage loss, increase the utilization rate of the tubular column and realize efficient production of a gas well.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas production, and in particular to a method for composite drainage and gas production using an integrated drainage and production pipe column. Background Art

[0002] During the production process of gas wells, the presence of gas and water in the same layer or bottom water often leads to liquid accumulation in the wellbore. Especially in the middle and late stages of production, when the formation pressure decreases, the gas production decreases, resulting in the gas being unable to carry liquid stably and continuously, causing liquid accumulation in the wellbore. The accumulated liquid will cause a high back pressure at the bottom of the well, affecting the gas well production and ultimate recovery rate. In severe cases, it may even cause gas well flooding.

[0003] Therefore, it is necessary to conduct research on corresponding drainage gas production processes. Common drainage gas production processes for gas wells, such as electric submersible pump drainage gas production, jet pump drainage gas production, mechanical pump drainage gas production, and plunger pump drainage gas production, all use a complete tubing string to drain the bottomhole liquid to the wellhead. The tubing string only serves as a drainage string, and gas is produced through the oil-casing annulus. This method results in low tubing string utilization, and the oil-casing annulus area is large, resulting in large slippage losses when the gas-liquid two-phase flow flows in the annulus, which is not conducive to gas carrying liquid. Summary of the Invention

[0004] The present invention provides a method for composite drainage and gas production using an integrated drainage and production pipe string, which can effectively reduce slippage losses, improve pipe string utilization, and increase gas well recovery rate.

[0005] This application provides the following technical solutions: A method for composite drainage and gas production using an integrated drainage and production string comprises the following steps: S1. Connect the integrated drainage and production string to the wellhead gas tree and lower the integrated drainage and production string into the well; S2. Sensors detect the temperature and pressure data at the bottom of the oil pipe and transmit them to the ground control cabinet via a data cable. When the submergence depth is not lower than a first preset threshold, the mechanical pump is started and the air inlet switch is closed. The accumulated liquid is lifted to the wellhead through the integrated drainage and production string to start the drainage operation. S3. When the submergence is less than the second preset threshold, the control cabinet stops the mechanical pump, the air inlet channel switch is turned on, the oil casing annulus and the integrated drainage and production string are combined to form a gas production channel, and the gas production operation begins.

[0006] Technical Principle: The integrated drainage and production string integrates a mechanical pump, temperature and pressure sensors, and an air inlet switch within the tubing. This system is lowered into the well along with the tubing and controlled by a surface control cabinet according to pre-set logic. By switching the air inlet switch, the integrated drainage and production string functions differently during different operation phases. When the air inlet is closed, the mechanical pump is activated for drainage; when the air inlet is opened, the mechanical pump is deactivated for gas production. Different thresholds for the mechanical pump's submergence level are used to determine whether drainage or gas production is initiated.

[0007] Beneficial effects: The integrated string has a simple structure and reliable control, and the entire process of water drainage and gas production can be completed with only a few devices.

[0008] Meanwhile, traditional gas production methods utilize the tubing annulus as a gas production channel. However, due to the large area of the tubing annulus, the gas-liquid carrying capacity is poor, resulting in significant slippage losses. The technical solution of this application fully ensures that gas is produced from the tubing. This not only increases tubing string utilization, but also reduces slippage losses due to the smaller cross-sectional area of the tubing string, further facilitating gas-liquid carrying and improving drainage efficiency.

[0009] Furthermore, it also includes: S4. When the sinking degree is greater than or equal to the first threshold, the control cabinet starts the mechanical pump, closes the air inlet channel switch, and starts the liquid drainage operation.

[0010] Beneficial effect: After the initial drainage and normal gas production, as the air pressure in the tubing annulus decreases, the dynamic liquid level gradually rises. At this time, the control cabinet determines that drainage is needed again based on the submergence degree and automatically switches to the drainage operation.

[0011] Furthermore, it also includes: S5. Loop through steps S3 and S4.

[0012] Beneficial effect: cyclically executing the steps of liquid drainage operation and gas production operation can effectively improve the production efficiency of gas wells and increase gas production.

[0013] Furthermore, during the composite drainage and gas production process, the valve corresponding to the tubing annulus is closed.

[0014] Beneficial effects: The casing annulus is always in a closed state controlled by the valve on the wellhead gas tree, which can avoid gas pressure loss during the drainage stage and increase the bottom hole back pressure; during the gas production stage, the gas is fully guaranteed to be produced from the oil pipe. Since the cross-sectional area of the pipe is smaller, the slip loss is small, which is conducive to gas carrying liquid and can improve the drainage efficiency.

[0015] Furthermore, the ground control cabinet calculates the submergence degree of the mechanical pump according to the temperature and pressure data.

[0016] Beneficial effects: The ground control cabinet converts the real-time data collected by the temperature and pressure sensors into the submergence of the mechanical pump, and selects to perform drainage or gas production operations according to the preset logic. It can adjust the working state of the integrated pipe string in real time to adapt to the changes in the dynamic liquid level, which is conducive to improving gas production efficiency and promptly eliminating production risks caused by excessively high dynamic liquid levels.

[0017] Furthermore, the first preset threshold and the second preset threshold are set according to the actual working conditions of the gas well.

[0018] Beneficial effect: The threshold can be flexibly adjusted to adapt to the design parameters and operating conditions of different gas wells.

[0019] Furthermore, the integrated production and drainage tubing used includes an oil pipe and a casing. The top of the oil pipe is hung in the casing through a oil pipe hanger. An oil pipe annulus is formed between the outer wall of the oil pipe and the inner wall of the casing. The oil pipe and the casing are respectively connected to the wellhead gas tree; a mechanical pump and a temperature and pressure sensor are provided at the bottom of the oil pipe, and an air inlet channel switch is provided inside the oil pipe.

[0020] Beneficial Effects: The integrated drainage and production string integrates multiple functional devices, including temperature and pressure sensors for collecting dynamic liquid level data, a mechanical pump for liquid drainage and lift, and an air inlet switch for switching the string's operating state. Centrally controlled by a ground control cabinet, the system enables the entire complex drainage and gas production process with a small number of components, resulting in a simple, stable, and reliable structure.

[0021] Furthermore, the mechanical pump is controlled in linkage with the air intake channel switch.

[0022] Beneficial effect: The mechanical pump and the air intake channel switch are controlled in conjunction with the ground control cabinet, ensuring reliable switching of the working status of the integrated system and ensuring the smooth progress of gas production.

[0023] Furthermore, the air intake channel switch is an electrically controlled sliding sleeve switch, which includes a driving motor fixedly connected to the inner wall of the oil pipe, a sliding sleeve adapted to the inner diameter of the oil pipe, and a push rod connecting the sliding sleeve and the driving motor. The wall of the oil pipe is provided with first air intake holes evenly distributed along the outer circumference, and the upper part of the sliding sleeve is provided with second air intake holes corresponding to the first air intake holes.

[0024] Beneficial effect: The electronically controlled sliding sleeve switch is used as the intake channel switch, which can realize precise control of the sliding sleeve and complete the opening and closing of the intake channel by whether different intake holes are connected.

[0025] Furthermore, the extension and retraction direction of the push rod is the same as the direction of the oil pipe axis. When the drive motor is not working, the length of the push rod is the shortest, and at this time the first air intake hole is aligned with the second air intake hole.

[0026] Beneficial effect: When the drive motor is not working, the air inlet channel is opened, and the gas production operation can be started normally after the pipe string is lowered into the well, which is more in line with the actual production conditions of the gas well. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural diagram of the integrated drainage and production string; Figure 2 This is a flow chart of the composite drainage gas recovery method; Figure 3 This is a schematic diagram of the working process of the sliding sleeve switch.

[0028] The symbols in the drawings of the specification include: oil pipe 1, casing 2, air intake channel switch 3, mechanical pump 4, temperature and pressure sensor 5, cable assembly 6, sliding sleeve 7, drive motor 8, push rod 9, first air intake hole 10, and second air intake hole 11. DETAILED DESCRIPTION

[0029] In the later stage of gas well production, liquid accumulation is serious and the dynamic liquid level is high. Appropriate drainage measures need to be taken to lower the dynamic liquid level to ensure smooth gas production. The following is a detailed description of the specific implementation method: Example 1 The integrated drainage and production string structure used in this embodiment is as follows: Figure 1 As shown, the system comprises tubing 1 and casing 2. The top of tubing 1 is hung in casing 2 via a tubing hanger, forming an annulus between the outer wall of tubing 1 and the inner wall of casing 2. Tubing 1 and casing 2 are each connected to a wellhead Christmas tree.

[0030] A mechanical pump 4 is installed at the bottom end of the oil pipe 1. This pump is powered by a surface booster and is controlled by a surface control cabinet. In practice, this pump can be an electric submersible pump or a plunger pump. A temperature and pressure sensor 5 is installed at the bottom end of the pump, transmitting real-time temperature and pressure data to the surface control cabinet via wired communication. The control cabinet pre-calibrates the temperature and pressure data and calculates the submergence depth of the pump 4 based on the pressure data.

[0031] A cable assembly 6 is fixed to the outer wall of the oil pipe 1 by a cable clip, including a data cable, a mechanical pump power supply cable and a mechanical pump control cable. The data cable is used to transmit the data collected by the temperature and pressure sensor 5 to the ground control cabinet; the mechanical pump power supply cable is connected to the ground power supply equipment and the mechanical pump 4 to provide driving power for the mechanical pump 4; the mechanical pump control cable is connected to the ground control cabinet and the mechanical pump 4 to realize the controlled start and stop of the mechanical pump 4.

[0032] An air intake channel switch 3 is installed in the oil pipe 1 above the mechanical pump 4. The ground control cabinet controls the opening and closing of the air intake channel switch 3 according to the change of the dynamic liquid level. In this embodiment, the air intake channel switch 3 adopts an electric control sliding sleeve switch. The specific structure is as follows: Figure 3 As shown. A fixedly connected drive motor 8 is provided on the inner wall of the oil pipe 1 above the mechanical pump 4. The drive motor is powered by a power line led out from the mechanical pump 4 and is started and stopped synchronously with the mechanical pump 4. A retractable push rod 9 is provided on the drive motor 8, and the retractable direction of the push rod 9 is the same as the direction of the axis of the oil pipe. The top of the push rod 9 is fixedly connected to the sleeve 7. The diameter of the sleeve 7 is the same as the inner diameter of the oil pipe 1. A first air intake hole 10 evenly distributed along the periphery is provided on the wall of the oil pipe 1, and a second air intake hole 11 corresponding to the first air intake hole 10 is provided on the upper part of the sleeve 7. When the drive motor 8 is working, the push rod 9 drives the sleeve 7 to move upward. At this time, the second air intake hole 11 moves upward and is not aligned with the first air intake hole 10. The side wall of the sleeve 7 is aligned with the first air intake hole 10. The oil pipe 1 and the oil pipe annulus are in a disconnected state, and the air intake channel is closed. Figure 3 As shown in the left figure. When the drive motor 8 is not working, the length of the push rod 7 is the shortest, and the sleeve 7 is correspondingly at the lowest position. At this time, the first air inlet hole 10 is aligned with the second air inlet hole 11, the air inlet channel is open, and the oil pipe 1 and the oil pipe annulus are in a connected state. The gas in the annulus can enter the oil pipe 1 through the first air inlet hole 10 and the second air inlet hole 11, as shown in FIG. Figure 3 As shown in the right figure.

[0033] The ground control cabinet is responsible for controlling the linkage between the mechanical pump 4 and the air inlet switch 3. When it detects that the mechanical pump 4's submergence level is no less than a first preset threshold, the ground control cabinet determines that the dynamic liquid level is high and requires drainage. It starts the mechanical pump 4 and closes the air inlet switch 3. At this point, the oil pipe 1 is disconnected from the oil pipe annulus. Using the intact oil pipe 1 as the drainage string, the mechanical pump 4 operates to lift the bottomhole liquid to the drainage pipe interface of the wellhead gas tree. When it detects that the mechanical pump 4's submergence level is less than a second preset threshold, the ground control cabinet determines that gas production conditions have been met, stops the mechanical pump 4, and opens the air inlet switch 3. At this point, the oil pipe 1 is connected to the oil pipe annulus. Gas in the oil pipe annulus can enter the oil pipe string through the air inlet switch, and then enter the gas production pipeline of the wellhead tree through the upper section of the oil pipe string, commencing gas production operations.

[0034] Figure 2 This is a schematic diagram of a method for composite drainage and gas recovery using the integrated drainage and recovery column, comprising the following steps: S1. Connect the integrated drainage and production string to the wellhead gas tree, close the valve corresponding to the tubing annulus, and lower the integrated drainage and production string into the well; S2. The sensor detects the temperature and pressure data at the bottom of the oil pipe and transmits it to the ground control cabinet via a data cable. The ground control cabinet calculates the submergence of the mechanical pump based on the temperature and pressure data. When the submergence is not lower than a first preset threshold, the ground booster equipment is activated to increase the 380V voltage at the well site to 1140V, driving the mechanical pump to lift the accumulated fluid through the oil pipe string to the wellhead, starting the liquid drainage operation. S3. When the submergence is less than a second preset threshold, the control cabinet shuts down the booster device and stops supplying energy to the mechanical pump. The air inlet switch is turned on, and the oil-casing annulus and the integrated drainage and production string are combined to form a gas production channel, and gas production operations begin. As the drainage operation progresses, the dynamic liquid level in the tubing gradually decreases. At this point, a sensor transmits bottomhole pressure data to the surface control cabinet, which converts the pressure data into the pump's submergence depth to determine the actual height of the dynamic liquid level. When the submergence depth falls below a second preset threshold, the control cabinet determines that gas production conditions have been met and shuts down the mechanical pump. This also stops the drive motor, causing the sleeve to descend, aligning the first air inlet with the second air inlet, connecting the tubing string with the tubing annulus. High-pressure gas in the annulus enters the tubing string through the air inlet channel. The tubing now serves as a gas production channel, smoothly carrying the liquid in the tubing string to the wellhead. Furthermore, because the tubing's cross-sectional area is smaller than that of the annulus, it can also carry a large amount of water along with the gas produced, further reducing bottomhole liquid accumulation and backpressure, thereby increasing the gas well's production capacity and recovery rate.

[0035] The first preset threshold and the second preset threshold are set according to the actual working conditions of the gas well to adapt to the different design parameters and actual working conditions of each gas well.

[0036] S4. When the submergence degree is greater than or equal to the first threshold, the control cabinet starts the mechanical pump, closes the air inlet channel switch, and starts the liquid discharge operation; As gas production progresses, the pressure in the tubing annulus gradually decreases, and the accumulated liquid in the tubing gradually increases, causing the dynamic liquid level to rise. When the dynamic liquid level exceeds the position of the first air inlet hole, the accumulated liquid blocks the annular gas from entering the tubing string. At this point, the ground control cabinet, using submergence-based logic, sends a command to start the mechanical pump and close the air inlet switch, commencing the liquid drainage operation.

[0037] S5. Loop through steps S3 and S4.

[0038] By cyclically executing the steps of drainage and gas production, the liquid accumulated at the bottom of the well can be discharged to the wellhead, thereby ensuring the opening rate of the gas well and improving the recovery rate.

[0039] Traditional gas production methods utilize the oil-casing annulus as a gas production channel. However, due to the large area of the oil-casing annulus, the gas-liquid carrying capacity is poor, resulting in significant slippage losses. In the technical solution of the present invention, the oil-casing annulus is always closed by a valve on the wellhead gas tree. This prevents gas pressure loss during the drainage phase and increases bottomhole back pressure. During the gas production phase, gas is fully produced from the oil pipe. This increases the utilization rate of the tubing, allowing the entire drainage and gas production process to be completed with less equipment. Furthermore, due to the smaller cross-sectional area of the tubing, slippage losses are minimized, which is more conducive to gas-liquid carrying and improves drainage efficiency.

[0040] The above are only embodiments of the present invention. The invention is not limited to the fields involved in this implementation case. Common knowledge such as the specific structure and characteristics of the scheme are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, which should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for composite drainage and gas production using an integrated drainage and production column, characterized by: The following steps are involved: S1. Connect the integrated drainage and production string to the wellhead gas tree and lower the integrated drainage and production string into the well; S2. Sensors detect the temperature and pressure data at the bottom of the oil pipe and transmit them to the ground control cabinet via a data cable. When the submergence depth is not lower than a first preset threshold, the mechanical pump is started and the air inlet switch is closed. The accumulated liquid is lifted to the wellhead through the integrated drainage and production string to start the drainage operation. S3. When the submergence is less than the second preset threshold, the control cabinet stops the mechanical pump, the air inlet channel switch is turned on, the oil casing annulus and the integrated drainage and production string are combined to form a gas production channel, and the gas production operation begins.

2. The method for composite drainage and gas production using an integrated drainage and production column according to claim 1, characterized in that: Also includes: S4. When the sinking degree is greater than or equal to the first threshold, the control cabinet starts the mechanical pump, closes the air inlet channel switch, and starts the liquid drainage operation.

3. The method for composite drainage and gas production using an integrated drainage and production column according to claim 2, characterized in that: Also includes: S5. Loop through steps S3 and S4.

4. The method for composite drainage and gas production using an integrated drainage and production column according to claim 1, characterized in that: During the composite drainage and gas production process, close the valve corresponding to the tubing annulus.

5. The method for composite drainage and gas production using an integrated drainage and production column according to claim 1, characterized in that: The ground control cabinet calculates the submergence degree of the mechanical pump according to the temperature and pressure data.

6. The method for composite drainage and gas production using an integrated drainage and production column according to claim 1, characterized in that: The first preset threshold and the second preset threshold are set according to the actual working conditions of the gas well.

7. The method for composite drainage and gas production using an integrated drainage and production column according to claim 1, characterized in that: The integrated production and drainage string used includes oil pipes and casing. The top of the oil pipe is hung in the casing through a oil pipe hanger. An oil pipe annulus is formed between the outer wall of the oil pipe and the inner wall of the casing. The oil pipe and casing are respectively connected to the wellhead gas tree; a mechanical pump and a temperature and pressure sensor are provided at the bottom of the oil pipe, and an air inlet channel switch is provided inside the oil pipe.

8. The method for composite drainage and gas production using an integrated drainage and production column according to claim 1, characterized in that: The mechanical pump is controlled in linkage with the air intake channel switch.

9. The method for composite drainage and gas production using an integrated drainage and production column according to claim 1, characterized in that: The air intake channel switch is an electrically controlled sliding sleeve switch, which includes a drive motor fixedly connected to the inner wall of the oil pipe, a sliding sleeve adapted to the inner diameter of the oil pipe, and a push rod connecting the sliding sleeve and the drive motor. The wall of the oil pipe is provided with first air intake holes evenly distributed along the outer circumference, and the upper part of the sliding sleeve is provided with second air intake holes corresponding to the first air intake holes.

10. The method for composite drainage and gas production using an integrated drainage and production column according to claim 9, characterized in that: The extension and contraction direction of the push rod is the same as the direction of the oil pipe axis. When the drive motor is not working, the length of the push rod is the shortest, and at this time the first air intake hole is aligned with the second air intake hole.

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