Gas well shaft cleaning and wax removing device

Abstract

The utility model relates to the technical field of methods or devices for cleaning well holes or wells, in particular to a cleaning and wax removing device for a gas well shaft. The gas well shaft cleaning and wax removing device comprises a center rod, a wax scraping structure is arranged on the center rod, the wax scraping structure comprises a rotary scraper, and the rotary scraper can move in the axial direction of the center rod and can rotate around the center line of the center rod. Limiting devices are arranged at the two ends of the rotary scraper and used for limiting the moving range of the rotary scraper on the center rod. And at least one scraper spring is arranged between the rotary scraper and the adjacent limiting device at at least one end of the rotary scraper and is used for providing counter-acting force to the rotary scraper when the rotary scraper is blocked. According to the gas well shaft cleaning and wax removing device, the scraper spring is arranged to provide necessary counter-acting force for the wax scraping structure, the wax scraping structure is helped to overcome obstacles when encountering the obstacles in the shaft, and the wax removing efficiency is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the method or device technical field of cleaning wellbore or well, especially relates to a gas well shaft cleaning and wax removing device. BACKGROUND

[0002] Crude oil usually contains a certain amount of wax, which is in a dissolved state under reservoir conditions. When the crude oil is produced and flows upward through the wellbore, its temperature and pressure conditions change. Specifically, as the crude oil flows upward from the deep formation, its temperature gradually decreases, and the solubility of paraffin in the crude oil decreases with the decrease in temperature, so when the temperature decreases to a certain extent, the wax begins to precipitate from the crude oil; as the crude oil flows upward from the deep formation, its pressure also gradually decreases, and when the pressure decreases to a certain extent, the solubility balance of paraffin in the crude oil may be destroyed, leading to precipitation of wax. The precipitated wax exists in the form of crystals, and these crystals will gradually grow and aggregate together. Due to the friction and adhesion of the wellbore wall, these wax crystals are easily deposited on the wellbore wall, forming a waxing phenomenon and generating wax crystals.

[0003] The deposition of wax crystals on the wellbore wall gradually reduces the area of the oil flow passage, resulting in a smaller flow passage for the oil to flow, and the oil needs to overcome greater resistance during flow, thereby causing the production pressure difference to become larger and the oil production to decrease. The deposition of paraffin can also change the flow characteristics of the crude oil, increase the fluid viscosity, and increase the energy consumption and reduce the pumping capacity during pumping, further reducing the recovery efficiency. With continuous deposition of paraffin, the tubing may be completely blocked in severe cases, resulting in production stoppage. Therefore, in order to maintain normal production of the oil well, regular wax removal operations are required.

[0004] In view of the problem of wax crystal deposition on the wall of the oil and gas wellbore, the existing wax removal methods usually include mechanical wax removal, thermal wax removal, and chemical wax removal. Mechanical wax removal uses a special tool to scrape off the wax on the tubing wall and relies on the liquid flow to carry the wax to the ground. Thermal wax removal uses thermal energy to increase the temperature of the liquid flow and the deposition surface to melt the wax deposited in the wellbore. The temperature and time need to be strictly controlled during the thermal wax removal process, and improper temperature and time control can easily cause re-deposition of wax blocks and blockage of the tubing. Chemical wax removal uses chemical agents to dissolve and carry the deposited paraffin out of the wellbore. The chemical agents may cause damage to the formation, and continuous addition and monitoring are required. In addition, chemical wax removal has high cost and may cause environmental pollution.

[0005] The mechanical wax cleaning tool of the coiled tubing well cleaning wax scraper is disclosed in Chinese Utility Model Patent No. CN212272125U, authorized on January 1, 2021. The coiled tubing well cleaning wax scraper includes a mounting cylinder, a first wax scraper body, and a second wax scraper body. The first and second wax scraper bodies are both cylindrical and are fitted in the middle of the mounting cylinder. A limiting device is fixedly installed on the lower part of the mounting cylinder to block the first or second wax scraper body. A first wax scraping strip and a second wax scraping strip are integrally fixed on the outer side of the first wax scraper body and the outer side of the second wax scraper body, respectively, in a spiral shape. The rotation direction of the first wax scraping strip on the first wax scraper body is opposite to that of the second wax scraping strip on the second wax scraper body. The coiled tubing well cleaning wax scraper achieves the purpose of cleaning the inner wall of the wellbore through the cooperation of the mounting cylinder, the first and second wax scraper bodies, and the first and second wax scraping strips.

[0006] The mechanical wax cleaning tool of the oil well production maintenance device is disclosed in Chinese Utility Model Patent No. CN212317941U, authorized on January 8, 2021. The oil well production maintenance device installs a wax scraping barrel on the sucker rod. Three layers of scraping blades are arranged on the outer wall of the wax scraping barrel along the axial direction. The wax scraping barrel rotates with the up-and-down reciprocating movement of the sucker rod to polish and remove the wax. When the wax crystals and structures in the wellbore are excessive, the above two mechanical wax cleaning tools may be stuck or blocked during upward or downward movement. Specifically, forced pulling during upward movement may cause deformation of the wax scraping strips or scraping blades, and in severe cases, may cause torsion or even breakage of the steel wire used to hoist the mechanical wax cleaning tool. Downward movement may cause sticking or even jamming of the wax scraping strips or scraping blades, affecting the wax cleaning effect and efficiency. Utility model content

[0007] The purpose of the present utility model is to provide a gas well bore cleaning and wax removing device to solve the problem of damage to the wax cleaning tool caused by upward sticking or downward blocking of the existing mechanical wax cleaning tool when the wax crystals and structures in the wellbore are excessive.

[0008] To solve the above problems, the gas well bore cleaning and wax removing device of the present utility model adopts the following technical solutions:

[0009] A gas well bore cleaning and wax removing device includes a central rod, a wax scraping structure is provided on the central rod, the wax scraping structure includes a rotary scraper, the rotary scraper is movable along the axial direction of the central rod and can rotate around the center line of the central rod, limit devices are provided at both ends of the rotary scraper to limit the movement range of the rotary scraper on the central rod; at least one scraper spring is provided between the rotary scraper and the adjacent limit device at one end of the rotary scraper to provide a reaction force to the rotary scraper when it is blocked.

[0010] Further, the wax scraping structure is provided with multiple groups in the axial direction of the central rod.

[0011] Further, the size of the rotating scraper of the multiple groups of the wax scraping structure gradually decreases from top to bottom.

[0012] Further, the wax scraping structure comprises a rotating shaft sleeve, and the rotating scraper is sleeved on the central rod through the rotating shaft sleeve.

[0013] Further, the rotating scraper is a three-wing spiral scraper.

[0014] Further, the three-wing spiral scraper comprises a center-holed mounting body and a three-wing spiral blade fixed to the outer wall of the mounting body.

[0015] Further, the limiting device comprises a limiting sleeve sleeved on the central rod and fixed on the central rod through a threaded hole on the limiting sleeve and a top screw.

[0016] Further, the top of the central rod is provided with a connecting thread for connecting a steel wire, a cable or a coiled tubing.

[0017] Further, the bottom of the central rod is provided with a spiral lead cone for passing through the rough surface or step-shaped scale part of the wellbore.

[0018] Further, the spiral lead cone is connected with the central rod through the connecting thread.

[0019] Beneficial effects: The gas well wellbore cleaning and wax removing device is an improved invention. Through the scheme, the wax scraping structure is arranged in the axial direction of the central rod and can rotate around the center line of the central rod, so that the cleaning and wax removing work is more effectively performed; the limiting device is used to limit the axial movement range of the wax scraping structure, so as to ensure the stability and controllability of the wax scraping structure during the working process; the scraper spring is further arranged between the wax scraping structure and the limiting device, which provides necessary reaction force when the wax scraping structure encounters obstacles in the wellbore, helps the wax scraping structure to overcome the obstacles and continuously and smoothly perform the cleaning and wax removing work. The gas well wellbore cleaning and wax removing device of the utility model sets the scraper spring to provide necessary reaction force for the wax scraping structure, helps the wax scraping structure to overcome the obstacles when the wax scraping structure encounters obstacles in the wellbore, and improves the wax removing efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a whole structure schematic view of one embodiment of the gas well wellbore cleaning and wax removing device of the utility model.

[0021] Figure 2 It is an assembly schematic view of one embodiment of the gas well wellbore cleaning and wax removing device of the utility model.

[0022] Figure 3 is a structure diagram of the rotating scraper in Figure 1 ;

[0023] Figure 4 is a three-dimensional schematic view of a three-wing spiral blade of an embodiment of the gas well wellbore cleaning and wax removing device;

[0024] Figure 5 is a structure diagram of the central rod in Figure 1 .

[0025] In the figure: 1, central rod; 2, rotating scraper; 3, scraper spring; 4, spacer block; 5, rotating shaft sleeve; 6, lower bottom plate; 7, mounting body; 8, three-wing spiral blade; 9, limiting sleeve; 10, threaded hole; 11, jackscrew; 12, connecting thread; 13, spiral lead cone. DETAILED DESCRIPTION

[0026] The features and performance of the present application are described in further detail below in connection with embodiments.

[0027] The gas well wellbore cleaning and wax removing device of the present application is provided with a scraper spring, which provides the necessary reaction force for the wax scraping structure when the wax scraping structure encounters an obstacle in the wellbore, helping the wax scraping structure to overcome the obstacle, avoiding damage to the wax removing device and improving the wax cleaning efficiency.

[0028] As a basic scheme, the gas well wellbore cleaning and wax removing device of the present application is as follows Figure 1 and Figure 2As shown, the gas well shaft cleaning and wax removing device mainly comprises a center rod 1 and a wax scraping structure, and the wax scraping structure comprises a rotary scraper 2. The center rod 1 serves as a support and guide structure of the entire device, so that the rotary scraper 2 can move freely in the axial direction of the center rod 1, ensuring that the rotary scraper 2 can perform cleaning work along the inner wall of the shaft, and flexibly adapt to various conditions in the shaft. If the shaft diameter is large or the shape is complex, a plurality of center rods 1 can be considered in parallel to increase the support area and the stability of the gas well shaft cleaning and wax removing device. The rotary scraper 2 can also rotate around the center line of the center rod 1, thereby improving the efficiency of cleaning and wax removing work. If there is a special coating or material on the inner wall of the shaft, a scraper made of flexible material such as a rubber scraper or a plastic scraper can be considered to reduce damage to the inner wall of the shaft. In order to ensure that the rotary scraper 2 does not move beyond the predetermined range in the axial direction, a limiting device is also provided on the center rod 1 to ensure the stability and controllability of the rotary scraper 2 during work. In addition, in order to further enhance the adaptability and working efficiency of the rotary scraper 2, a scraper spring 3 is arranged between the rotary scraper 2 and the limiting device. When the rotary scraper 2 encounters an obstacle in the shaft, the scraper spring 3 can provide the necessary reaction force to help the rotary scraper 2 overcome the obstacle and continue to smoothly perform cleaning and wax removing work. In order to protect the scraper spring 3 and the rotary scraper 2 from interfering with each other during work, a spacer 4 can be added between the scraper spring 3 and the rotary scraper 2 to reduce the interference between the scraper spring 3 and the rotary scraper 2.

[0029] As a preferred embodiment, the wax scraping structure is provided in multiple groups along the axial direction of the center rod 1, and the multiple groups of wax scraping structures are kept at a sufficient protective distance by the limiting device. The multiple groups of wax scraping structures can be distributed along the length direction of the center rod 1 to cover different positions of the shaft, ensuring comprehensive cleaning of the inner wall of the shaft. The multiple groups of wax scraping structures simultaneously scrape wax deposits in different areas and cooperate to achieve cleaning of the entire shaft. The multiple groups of wax scraping structures can reduce the number of cleaning operations and costs, improve cleaning efficiency and effect, and also prolong the service life of the equipment, reducing the cost of replacing and maintaining the equipment.

[0030] In a preferred embodiment, the size of the rotating scrapers 2 in the multiple sets of wax-scraping structures gradually decreases from top to bottom. Since the wellbore contains wax layers of varying diameters and thicknesses, during the scraping, peeling, and removal of wax crystals and deposits from the inner wall of the tubing, the lower, smaller scraper first widens the channel, followed by further scraping with the upper, larger scraper, gradually cleaning away the wax crystals and deposits inside the tubing. This design of rotating scrapers 2, which gradually decreases in size from top to bottom, more effectively removes the wax layer from the wellbore while reducing potential damage to the wellbore wall. This not only improves the efficiency of cleaning and dewaxing but also ensures the reliability and durability of the device in complex wellbore environments. If the wellbore is short or the wax deposit is minimal, the number of wax-scraping structures can be reduced to lower the cost and complexity of the device. Conversely, if the wellbore is long or the wax deposit is severe, the number of wax-scraping structures can be appropriately increased to improve the cleaning effect.

[0031] As a preferred implementation method, such as Figure 3 As shown, the wax scraping structure includes a rotating bushing 5, and the rotating scraper 2 is fitted onto the central rod 1 via the rotating bushing 5. The inner diameter of the rotating bushing 5 is slightly larger than the outer diameter of the central rod 1 to allow the rotating scraper 2 a certain degree of freedom of movement on the central rod 1. Specifically, because the inner diameter of the rotating bushing 5 is slightly larger than the outer diameter of the central rod 1, the rotating scraper 2 can move freely along the axial direction on the central rod 1, including rotation and slight axial movement. In actual production, the inner wall of the wellbore will have a certain degree of inclination. The rotating scraper 2 is connected to the central rod 1 via the rotating bushing 5. The presence of the rotating bushing 5 allows the rotating scraper 2 to have a certain degree of freedom of movement in the radial direction of the central rod 1. This degree of freedom of movement can prevent the rotating scraper 2 from causing the central rod 1 to rotate and the hoisting wire from twisting when working on the inclined section of the wellbore inner wall, allowing the scraper to better adapt to the irregular shape of the wellbore inner wall and the thickness variation of the wax layer. The rotating bushing 5 includes a body and a lower base plate 6. The rotating scraper 2 is mounted on the central rod 1 via the body and the lower base plate 6. The rotating bushing 5 allows the rotating scraper 2 to rotate freely on the central rod 1, reducing direct friction with the central rod 1 and extending the service life of both the rotating scraper 2 and the central rod 1. The wax scraping structure is mounted on the central rod 1 via the rotating bushing 5, facilitating disassembly and replacement, and reducing maintenance costs and time. In other embodiments, a bearing can be used instead of the rotating bushing 5. Bearings have higher load-bearing capacity and wear resistance, but the greater frictional resistance increases energy consumption. Although using a bearing increases energy consumption, it still achieves the purpose of effective wax scraping.

[0032] As a preferred embodiment, the rotary scraper 2 is a three-winged spiral scraper, the design of which increases the contact area with the inner wall of the wellbore, improves the scraping efficiency, and ensures that the wax can be effectively scraped off. In other embodiments, a scraper with more wings is used to further increase the contact area with the inner wall of the wellbore and improve the cleaning efficiency, but too many wings can increase the friction resistance and energy consumption; although a scraper with more wings increases energy consumption, it still achieves the purpose of effectively scraping wax.

[0033] As a preferred embodiment, the three-winged spiral scraper includes a center-holed mounting body 7 and a three-winged spiral blade 8 fixed to the outer wall of the mounting body 7. Specifically, the mounting body 7 is a center-holed conical body, and the upper end face of the conical body has a larger diameter than the lower end face, which makes the three-winged spiral blade 8 better adapt to the change in the taper of the inner wall of the wellbore when moving axially. The three-winged spiral blade 8 is fixed to the outer wall of the conical body, and a perspective view of the three-winged spiral blade 8 is shown in Figure 4 , which is arranged in a spiral manner around the conical body, can effectively scrape off the wax layer on the inner wall of the wellbore. The spiral blade not only improves the scraping efficiency of the scraper, but also enables the scraper to generate a certain cutting force when rotating, thereby better removing stubborn wax layers. When the three-winged spiral blade 8 is made of metal, it is welded to the outer wall of the conical body, and when the three-winged spiral blade 8 is made of non-metal material, it is fixed to the outer wall of the conical body by screws.

[0034] As a preferred embodiment, the limiting device includes a limiting sleeve 9, as shown in Figure 1 and Figure 5 , which is fixed to the center rod 1 by the threaded hole 10 on it cooperating with the jackscrew 11. The limiting sleeve 9 is fixed to the center rod 1, limiting the movement of the wax scraping structure in the axial direction. The limiting sleeve 9 is fixed by the threaded hole 10 on it, the jackscrew 11, and the jackscrew groove 12, which can ensure that the wax scraping structure is uniformly and stably limited when moving axially. When the wax scraping structure is subjected to the reaction force of the inner wall of the wellbore, the limiting sleeve 9 can provide additional support to maintain the stability and cleaning efficiency of the wax scraping structure. In the specific implementation process, multiple threaded holes 10, jackscrews 11, and jackscrew grooves 12 can be uniformly fixed along the radial direction of the center rod 1 to ensure that the wax scraping structure is uniformly stressed during operation, reducing vibration and deviation caused by uneven stress. Not only does this improve the stability of the wax scraping structure during movement, but it also ensures the reliability and safety of the entire device during the cleaning and wax removal process.

[0035] As a preferred embodiment, the top of the center rod 1 is provided with a connecting thread 13 for connecting a wire, a cable or a coiled tubing. The connecting thread 13 is mainly used for reliable connection with transmission media such as wire, cable or coiled tubing. These transmission media connect the power source on the ground with the clean wax removal tool in the wellbore, ensuring that the power can be stably and efficiently transmitted to the downhole. The connecting thread 13 can ensure the stable connection between the power source and the clean wax removal tool, avoiding the loss of power and the interruption of operation due to unstable connection, and improving the efficiency and continuity of the clean wax removal operation.

[0036] As a preferred embodiment, the bottom of the center rod 1 is provided with a spiral lead cone 14 for passing through the uneven surface or stepped scale parts of the wellbore. The spiral lead cone 14 is shaped like a gradually tapered spiral, which design makes it have better cutting and guiding ability. When the device moves down, the spiral lead cone 14 can gradually cut into the scale or irregular surface like a drill bit, effectively removing these obstacles. At the same time, the shape of the spiral helps to guide the device to move along the center line of the wellbore, preventing it from deviating and affecting the cleaning effect.

[0037] As a preferred embodiment, the spiral lead cone 14 is connected with the center rod 1 through the connecting thread 13. The connecting thread 13 tightly connects the spiral lead cone 14 and the center rod 1 together through threads, forming a stable whole. This connection method is not only firm and reliable, but also can withstand various challenges brought by the complex environment in the wellbore, such as high temperature, high pressure, corrosion, etc. The connecting thread 13 makes the connection between the spiral lead cone 14 and the center rod 1 simple and fast. Workers can easily complete the installation or disassembly work by rotating the connecting thread 13, which greatly improves the work efficiency and reduces the operation difficulty. The stable connecting thread 13 ensures the stable work of the spiral lead cone 14 in the wellbore, avoiding the problems of operation interruption or low efficiency caused by unstable connection. This helps to shorten the clean wax removal period and improve the operation efficiency.

[0038] The specific implementation process of this embodiment is as follows: the top of the center rod 1 is provided with an upper connector thread for connecting a wire or a cable, the bottom of the center rod 1 is provided with a lower connector thread for connecting the spiral lead cone 14, the limiting sleeve 9 is provided with a threaded hole, the top wire 11 passes through the threaded hole and is inserted into the threaded hole 10 to fix the limiting sleeve 9, the scraper spring 3 is free between the limiting sleeve 9 and the spacer block 4 and should be in a fully expanded state during assembly, the spacer block 4 is between the scraper spring 3 and the three-wing spiral scraper, so that the force transmission between the three-wing spiral scraper and the scraper spring 3 is uniform, the rotary shaft sleeve 5 is connected with the lower bottom plate 6 through threads, the three-wing spiral scraper is installed on the scraper rotary shaft sleeve 5 through interference fit, and after the assembly of the three-wing spiral scraper is completed, the spiral lead cone 14 is connected with the center rod 1 through threads.

[0039] The wax removal device is carried by the steel wire, the cable or the coiled tubing to be lowered into the gas well tubing from the ground. If the wax crystal and the deposit are not in the gas well tubing, the wax removal device continues to be lowered, and the tension of the steel wire, the cable or the coiled tubing is monitored by the ground instrument. If the wax removal device encounters the wax crystal and the deposit, according to the different thickness of the deposit in the tubing, the wax removal device has a plurality of different sizes of the wax scraping structure with different passing capacities. When the wax crystal and the deposit are serious, the gas flow channel is small, the three-wing spiral scraper at the bottom of the wax removal device cannot pass the deposit section, the wax removal device cannot be lowered, the lowering tension of the steel wire, the cable or the coiled tubing is abnormally reduced, and the center rod 1 is moved up and down by continuously lifting and lowering. The wax removal device is impacted by the three-wing spiral scraper at the bottom under the action of the reaction force of the scraper spring 3 and the gravity, and the three-wing spiral scraper impacts the wax crystal and the deposit. If the well is opened, the wax crystal and the deposit are taken out of the well under the action of the gas flow. If the well is closed, the wax crystal and the deposit fall to the bottom of the well under the action of the gravity. The wax crystal and the deposit on the inner wall of the tubing are continuously scraped, peeled and removed by the three-wing spiral scraper at the bottom. After passing the deposit section, the three-wing spiral scraper at the middle continuously acts on the wax crystal and the deposit for scraping, peeling and removing. Similarly, the three-wing spiral scraper at the top continuously acts on the wax crystal and the deposit, and finally the wax crystal and the deposit are cleaned. Through the above operation, the wax crystal and the deposit in the production tubing are cleaned.

[0040] The above is only a preferred embodiment of the present application, and does not limit the present application. The patent protection scope of the present application is subject to the claims, and any equivalent structural changes made according to the content of the specification and the drawings should be included in the protection scope of the present application.

Claims

1. A gas well bore cleaning and wax removal apparatus comprising a central rod having a wax removal structure thereon, the wax removal structure comprising a rotary scraper, the rotary scraper being movable in an axial direction of the central rod and rotatable about a centre line of the central rod, the rotary scraper having a stop means at each end to limit the range of movement of the rotary scraper on the central rod; characterised in that, At least one scraper spring is arranged between the rotary scraper and the adjacent limiting device at least at one end of the rotary scraper to provide a reaction force to the rotary scraper when the rotary scraper is blocked.

2. A gas well bore cleaning and paraffin removal device according to claim 1, characterized in that, The wax scraping structure is provided with multiple groups in the axial direction of the central rod.

3. A gas well bore cleaning and paraffin removal apparatus as defined in claim 2, wherein, The size of the rotary scraper of the multiple groups of the wax scraping structure is gradually reduced from top to bottom.

4. A gas well bore cleaning and paraffin removal apparatus according to any one of claims 1-3, characterized in that, The wax scraping structure comprises a rotary shaft sleeve, and the rotary scraper is sleeved on the central rod through the rotary shaft sleeve.

5. A gas well bore cleaning and paraffin removal apparatus as defined in claim 4, wherein, The rotary scraper is a three-wing spiral scraper.

6. The gas well bore cleaning and paraffin removal apparatus of claim 5, wherein, The three-wing spiral scraper comprises a center-holed mounting body and a three-wing spiral blade fixed to the outer wall of the mounting body.

7. The gas well bore cleaning and paraffin removal apparatus of claim 1, wherein, The limiting device comprises a limiting sleeve sleeved on the central rod and fixed on the central rod through a threaded hole on the limiting sleeve and a top pin.

8. A gas well bore cleaning and paraffin removal apparatus as claimed in claim 6 or 7, characterised in that, The top of the central rod is provided with a connecting thread for connecting a wire, a cable or a coiled tubing.

9. The gas well bore cleaning and paraffin removal apparatus of claim 8, wherein, The bottom of the central rod is provided with a spiral guide cone for passing through a rough surface or a stepped scale part of a wellbore.

10. The gas well bore cleaning and paraffin removal apparatus of claim 9, wherein, The spiral guide cone is connected with the central rod through the connecting thread.

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