Movable CO2 drive oil field wellhead pressure relief device
By designing a movable pressure relief device in the wellhead of the CO2-driven oil field, the problems of freezing and high gas discharge during the wellhead pressure relief process are solved, and the continuity and safety of the wellhead pressure relief are achieved and production efficiency is improved.
Patent Information
- Application Number
- CN202311496029.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-10
- Publication Date
- 2025-05-13
AI Technical Summary
In the wellhead of the CO2-driving oil field, the high gas-liquid ratio and pressure fluctuations lead to the throttling effect during the pressure relief process, the temperature drop leads to the freezing of pipelines, and the emergency pressure relief of tankers has safety and environmental hazards of high CO2-containing gas leaking into the atmosphere.
A movable CO2-driven oilfield wellhead pressure relief device is designed, and the pressure is adjusted using a throttle valve, and the fluid produced in the wellhead is exchanged through an electric heating device to avoid freezing and high gas leakage.
The continuity and safety of the wellhead pressure relief process is achieved, the frequency of emergency pressure relief and operation risks of tankers is reduced, the efficiency of gas traversal regulation is improved, and efficient and stable production is ensured.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of heat exchange equipment, and in particular relates to a movable CO2 flooding oil field wellhead pressure relief device. Background Art
[0002] my country's major oil fields have carried out experimental work on CO2 flooding, which has greatly improved the recovery rate of crude oil and achieved large-scale production. [1-3] Due to the use of CO2 flooding technology, the produced fluid has a high gas-liquid ratio. In order to ensure production safety, the oil field site discharges the overpressured casing gas into the oil production pipeline, which further increases the gas-liquid ratio of the produced fluid, makes the gas-liquid fluctuation more intense, and even forms slug flow. [4-5] , resulting in fluctuations in the production of the gathering and transportation system, frequent fluctuations in the wellhead casing pressure and single-ring production pressure, affecting the single well production and stable gathering and transportation. In order to reduce the impact, it is necessary to relieve the pressure of the plug flow in the effective well section. At present, the effective well pressure relief adopts tank truck emergency pressure relief. Due to the high wellhead pressure, a throttling effect will occur during the pressure relief process, and the temperature drop will cause the medium in the pipeline to freeze and block. At the same time, the gas volume in the output fluid is too large. The emergency pressure relief of the tank truck will cause the high-CO2 associated gas to be released into the atmosphere, posing a safety and environmental hazard. Summary of the invention
[0003] In order to overcome the deficiency of the prior art that the wellhead cannot directly and continuously perform emergency pressure relief and venting as the number of gas crosstalk wells increases, the present invention provides a movable CO2 drive oil field wellhead pressure relief device, a throttle valve is designed to reduce the pressure, and the output fluid of the effective well is heat exchanged through an electric heating device to meet the normal entry into the gathering and transportation system operation requirements, reduce the frequency of emergency pressure relief and operation risks of tank trucks, improve the efficiency of gas crosstalk regulation, and ensure efficient and stable production.
[0004] The above-mentioned purpose of the present invention is achieved through the following technical scheme: a movable CO2 drive oil field wellhead pressure relief device, including a head, a heat exchange tube, a support plate, a cylinder, a water replenishment barrel, and a saddle. The head is installed in an arc shape at both ends of the cylinder to form a closed shell, the heat exchange tube is arranged inside the cylinder, the support plates are cross-arranged inside the cylinder, the water replenishment barrel penetrates into the cylinder, and the water replenishment barrel is provided with a saddle at the top of the outer part of the cylinder.
[0005] Furthermore, the heat exchange tube is divided into a liquid inlet tube and a liquid outlet tube, wherein the liquid inlet tube passes through a head at one end, and the end of the passing part is the liquid inlet, and the liquid outlet tube passes through a head at one end, and the end of the passing part is the liquid outlet.
[0006] Furthermore, the sealing head is provided with an electric heating rod opening equipped with a flange.
[0007] Furthermore, the sealing head and the cylinder are provided with thermometer ports connected by threads.
[0008] Furthermore, a breathing port equipped with a flange is provided on the top of the cylinder.
[0009] Furthermore, a magnetic flap port equipped with a flange is provided on the top of the cylinder.
[0010] Furthermore, the saddle and the bottom of the cylinder are provided with a water filling port with a water filling cover.
[0011] Furthermore, a sewage outlet equipped with a flange is provided at the bottom of the cylinder.
[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: the device adopts a skid-mounted design, which is convenient for relocation and movement, simple process connection, and convenient installation and maintenance; the device adopts a throttle valve for pressure regulation, and heats the wellhead product through heat exchange, thereby avoiding pipeline freezing and pressure holding, personnel safety and environmental protection risks during the pressure relief process, and achieving full process sealing and no leakage; the device reduces the frequency of emergency pressure relief of tank trucks and operational risks, improves the efficiency of gas channeling control, and ensures efficient and stable production. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.
[0014] Figure 1 This is a structural diagram of a CO2 flooding oil field wellhead pressure relief device of the present invention;
[0015] Figure 2 This is the arrangement form of the heat exchange tubes in the CO2 flooding oil field wellhead pressure relief device of the present invention;
[0016] Figure 3 is a structural diagram of a device in which heat exchange tubes are arranged in staggered layers in Example 1 of the present invention;
[0017] Figure 4 is a side cross-sectional view of the device structure in which the heat exchange tubes are arranged in staggered layers in Example 1 of the present invention;
[0018] Figure 5 It is a side view of the device structure in which the heat exchange tubes are arranged in staggered layers in Example 1 of the present invention;
[0019] Figure 6 The present invention shows a front view (a) and a top view (b) of the outer part of the water replenishment barrel of the wellhead pressure relief device of the CO2 flooding oil field.
[0020] In the figure, 1. head; 2. heat exchange tube; 3. support plate; 4. cylinder; 5. water supply bucket; 6. water supply port; 7. electric heating rod port; 8. liquid inlet pipe; 9. liquid outlet pipe; 10. breathing port; 11. thermometer port; 12. magnetic flap port; 13. saddle; 14. sewage outlet. DETAILED DESCRIPTION
[0021] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.
[0022] Example 1
[0023] A movable CO2 flooding oil field wellhead pressure relief device. The wellhead produced fluid heat exchange adopts the method of electrically heating water, and water heating the produced fluid, heating the produced fluid before throttling, increasing the temperature of the produced fluid, and the produced fluid will not freeze after throttling.
[0024] The equipment structure is that two heads are welded to the cylinder to form a shell; the pipeline adopts straight pipes and elbows welded to form a high-pressure coil, and a support plate is provided for it; two connecting pipes are left on the two heads of the shell and equipped with flanges to realize the installation of the electric heating rod; the interfaces on the shell also include the inlet and outlet of the high-pressure coil, the water supply port, the breathing valve port, the thermometer port, the magnetic flap liquid level gauge port, and the sewage port. Except that the thermometer port is connected by threads and the water supply port is closed by a water supply cover, the other ports are equipped with flanges and connected to the outside world by flanges; the whole equipment is supported by a standard saddle.
[0025] The produced fluid of CO2 flooding wells has the following three characteristics. First, the produced fluid temperature is low, the wellhead temperature is about 15°C, the environment temperature is low in winter, the average temperature in January is -17°C to -19°C, and the produced fluid temperature drops greatly. Second, the wellhead pressure is high after gas breakthrough, the shut-in pressure can reach 16MPa, and the flow pressure is 5-10MPa. Third, the freezing point of crude oil in the produced fluid is relatively high, and it is easy to freeze and block below the freezing point. Therefore, CO2 flooding wells need to be heated before throttling to ensure that the produced fluid at the wellhead does not freeze and block. Due to the unstable wellhead pressure, the coil needs to bear the high-pressure unstable pressure load. At the same time, the equipment structure needs to be as small as possible, the material needs to be resistant to CO2 corrosion, and it needs to solve the freezing and blocking problem in winter.
[0026] In order to solve this problem, we first calculate the heat exchange of the equipment to obtain the amount of heat required for the equipment to overcome freezing and blockage, and then perform thermal calculations to derive the selection of electric heating rods. When designing the heat exchange coil, the length of the heat exchange tube is determined based on the required heat exchange area, and the diameter of the heat exchange tube depends on the diameter of the wellhead pipe. Then we consider how to coil the tube to save the most volume. Since the coil diameter is DN40, the spacing is large when directly U-made, and it is relatively labor-intensive, so the coil is made in the form of a straight tube plus a 180° elbow.
[0027] The coil arrangement can be a square arrangement, b rotated square arrangement, c triangle 45° arrangement, d regular triangle arrangement ( Figure 2). Based on the factors of pipe diameter, elbow bending radius, manufacturing, and the size of the arrangement, the coils are arranged in a D-shaped and triangular form. During the manufacturing process, it was found that when the ends of the straight pipes of the heat exchange coils are arranged in a flush structure, the coils of DN40 and below cannot meet the requirements of the welding space due to the small 180° bending radius. For this reason, we arrange the straight pipe sections of the heat exchange coils in staggered layers, as shown in the following example. Figure 3 shown.
[0028] The staggered layout is adopted to maximize the use of heat exchange space. The cross section of the coil is shown in Figure 04, and the end of the coil is shown in Figure 04. Figure 4 The coils are arranged in a way that maximizes the heat exchange area of the coils, while also saving space occupied by the coils, making the equipment compact and saving materials.
[0029] The interface layout of the device is as follows Figure 1 As shown, there are mainly heat exchange coils, electric heating rod ports, thermometer ports, liquid level gauge ports, water replenishment ports, breathing valve ports, and sewage ports. When designing the first equipment, we also considered adding a hot water circulation port. The main purpose is to prevent the flow rate of the liquid from the wellhead from being insufficient, and the heat of the hot water cannot be taken away in time, resulting in low heat exchange efficiency and failure to meet production needs. For this reason, we added a hot water circulation outlet and a hot water circulation inlet to increase the heat transfer coefficient and prevent the temperature of the fluid produced from the wellhead from being insufficiently raised, which cannot solve the problem of pressure drop freezing. Figure 5 Figure a is a side view of the inlet and outlet. This side has the inlet and outlet of the heat exchange coil, the electric heating rod connection port, and the thermometer port linked to the electric heating rod on this side. Figure 5 Figure b is a side view of the circulation standby port, which mainly includes the circulation standby port, the electric heating rod installation port, and the thermometer interface linked to the electric heating rod. After using the first device at the wellhead, it was concluded that the heat transfer effect of the device was good and there was no need to circulate hot water, so the circulation standby port of the device was cancelled in subsequent devices.
[0030] Since the equipment is used at the wellhead, it is mostly located in the wilderness, with a large number of single wells and platforms on site, and there is no condition for manned well site. Therefore, it is necessary to equip it with a remote monitoring and management system, which can display the operation status in the duty room. To achieve the goal of unmanned wellhead equipment, remote monitoring of the Internet of Things must be used. On the equipment, we use a thermometer interlocked with an electric heating rod. First, determine the temperature control range according to the incoming liquid temperature. When the temperature reaches the maximum temperature, the control system will turn off the switch of the electric heating rod. When the temperature drops to the lower limit of the temperature control, the control system will turn on the switch of the electric heating rod to heat the water in the equipment.
[0031] Since the shell of the equipment is designed for normal pressure and the pipe line is designed for high pressure, the shell of the equipment must be kept at normal pressure during operation to prevent the equipment from being insufficiently strong due to the pressure build-up. Although the equipment is equipped with a safety valve, a water supply port cover is also provided on the water supply port for safety reasons. The cover is made of aluminum and is lightweight. It can not only cover the water supply port to prevent heat loss and block rainwater from flowing into the equipment, but also provide double insurance for protecting the shell side of the equipment at normal pressure. If the breathing valve cannot exhale the steam in the tank in time, as the steam accumulates more and more, the cover of the water supply port will be pushed open, and the pressure in the shell side can be released to ensure the safety of the equipment. The inner extension pipe of the water supply port extends into the center line of the tank body to prevent the tank from having a spray-type cooling effect when adding cold water to the tank. The pipe is introduced near the electric heating rod to prevent the upper water of the equipment from cooling too quickly. The water supply port is also equipped with a buffer chamber, which is not only convenient for operation when the inner diameter of the port is large during water supply, but also can realize a storage chamber when the hot water in the tank expands and overflows upward. See the installation diagram of the water filling port. Figure 1 , see the structural diagram of the water supply port Figure 6 Figure a is the main view, and Figure b is the top view. The cover of the water filling port is connected to the water filling port cylinder by a rotating shaft. A handle is also provided on the cover of the water filling port to facilitate the opening and closing of the water filling cover. The rotating shaft turns to the side of the super platform operating surface for easy opening and closing.
[0032] Example 2
[0033] A mobile CO2 flooding oil field wellhead pressure relief device, such as Figure 1 As shown, it includes two side heads 1 and heat exchange tubes 2. The heat exchange tubes 2 are supported by support plates 3. The heat exchange tubes 2 are arranged in a shell 4 and are replenished with water through a water replenishing bucket 5. A saddle 6 and a skid seat are arranged at the bottom of the device.
[0034] Working process and principle description:
[0035] The working principle of the equipment is that clean water enters the equipment housing 3 through the water replenishment bucket 5, fills the tank, and the height of the liquid level can be seen through the magnetic flap liquid level gauge. The water replenishment bucket 5 adopts a flip-up aluminum plate cover. If the temperature inside the equipment is too high and too much water vapor accumulates, when the water vapor passes through the breathing valve and has no time to release the internal pressure, the water replenishment cover can be flipped up to release the internal pressure to ensure that the equipment is in a normal pressure state. Electric heating rods are installed on the left and right heads 1 of the equipment respectively. The electric heating rod boils the water in the equipment housing 3, and the hot water transfers the heat to the coil 2. There is flowing wellhead produced fluid in the coil 2. The coil 2 transfers heat to the wellhead produced fluid. The wellhead produced fluid is heated during the time it flows in the coil 2, effectively preventing the wellhead throttling and freezing, and realizing the pressure reduction and transportation of the produced fluid. There are also three thermometer interfaces on the equipment. One thermometer adopts remote control to realize remote monitoring, and the two thermometer ports are interlocked with the electric heating rod switch to control the start and stop of the electric heating rod. When the temperature of the water in the equipment reaches the highest value of the temperature control, the electric heating rod switch is turned off and the equipment is in power saving mode; when the temperature of the water in the equipment drops to the lowest value of the controlled temperature, the electric heating rod switch is turned on, the electric heating rod heats the water in the equipment, and the equipment is in heating mode. The magnetic flap level gauge also has a remote transmission function to achieve remote monitoring. When the water in the equipment is lower than the highest point of the coil, the equipment manager will go to the site to add water. The wellhead pressure relief device is also equipped with a breathing valve to keep the equipment in a normal pressure state to ensure the safety of the equipment.
[0036] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.
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Claims
1. A movable CO2 flooding oil field wellhead pressure relief device, characterized in that: The invention comprises a sealing head (1), a heat exchange tube (2), a support plate (3), a cylinder (4), a water replenishing bucket (5), and a saddle (6); the sealing head (1) is installed at both ends of the cylinder (4) in an arc shape to form a closed shell; the heat exchange tube (2) is arranged inside the cylinder (4); the support plates (3) are cross-arranged inside the cylinder (4); the water replenishing bucket (5) penetrates into the cylinder (4); and the water replenishing bucket (5) is provided with a saddle (6) at the top end of the outer part of the cylinder (4).
2. The mobile CO2 flooding oil field wellhead pressure relief device according to claim 1 is characterized in that: The heat exchange tube (2) is divided into a liquid inlet tube (8) and a liquid outlet tube (9), wherein the liquid inlet tube (8) passes through the end cap (1) at one end, and the end portion of the passing portion is the liquid inlet, and the liquid outlet tube (9) passes through the end cap (1) at one end, and the end portion of the passing portion is the liquid outlet.
3. The movable CO2 flooding oil field wellhead pressure relief device according to claim 1 is characterized in that: The sealing head (1) is provided with an electric heating rod opening (7) equipped with a flange.
4. The movable CO2 flooding oil field wellhead pressure relief device according to claim 1 is characterized in that: The sealing head (1) and the cylinder (4) are provided with a thermometer port (11) connected by threads.
5. The movable CO2 flooding oil field wellhead pressure relief device according to claim 1 is characterized in that: The top of the cylinder (4) is provided with a breathing port (10) equipped with a flange.
6. The movable CO2 flooding oil field wellhead pressure relief device according to claim 1 is characterized in that: The top of the cylinder (4) is provided with a magnetic flap opening (12) equipped with a flange.
7. The movable CO2 flooding oil field wellhead pressure relief device according to claim 1 is characterized in that: The saddle (13) and the top of the cylinder (4) are provided with a water replenishment port (6) with a water replenishment cover.
8. The movable CO2 flooding oil field wellhead pressure relief device according to claim 1 is characterized in that: The bottom of the cylinder (4) is provided with a sewage outlet (14) equipped with a flange.