Well washing scraper

Abstract

The utility model discloses a well flushing scraper which comprises a recycling head, a sliding shaft, a fixing sleeve, a sliding claw, a fixing cap, a conical head, a release pin and a fixing shaft, the fixing sleeve is installed on the outer surface of the sliding shaft, the sliding claw and the fixing cap are installed on the outer surface of the fixing sleeve, and through holes penetrating in the radial direction are formed in the outer cylindrical face of the sliding shaft and the outer cylindrical face of the sliding claw. The fixed shaft is installed in the through holes of the sliding shaft and the sliding claw, key grooves which penetrate in the radial direction and are symmetrically arranged are formed in the outer cylindrical face of the fixed sleeve, and the sliding claw is in an open state when the fixed shaft is located at the uppermost end of the key grooves of the fixed sleeve. When the fixing shaft is located at the lowermost end of the key groove of the fixing sleeve, the sliding claw is embedded into the annular cavity of the fixing sleeve and the annular cavity of the fixing cap and is in a contraction state. The well washing scraper can thoroughly clean impurities such as scales, oil sludge and the like on the inner wall of an oil pipe, has the advantages of being simple, efficient and safe, improves well washing efficiency, and meets construction operation requirements.

Description

Technical Field

[0001] The utility model relates to the field of oil field scrapers, in particular to a well-washing scraper. Background Art

[0002] During water well production, normal testing is affected by corrosion, scaling, and sludge on the inner wall of the tubing. Statistics show that the length of tubing above the casing packer in water injection wells accounts for 93% of the total tubing length, while the length of tubing within the distance between the packers accounts for only 7%. During water volume inspection and water volume measurement and adjustment tests in water wells, approximately 40% of wells experience blockage in different layers during the lowering of the tubing above the casing packer. This is mainly manifested in increased injection pressure, decreased wellhead water volume, and test resistance in some wells. This indicates that scraping and disturbing the inner wall of the tubing during the lowering of the test instrument causes corrosion, scaling, sludge, and other impurities to fall off the tubing, clogging the nozzle or causing resistance in the test instrument within the distance between the packers. The above problems require well flushing to clear the blockage.

[0003] At present, the oil field does not have special tools for cleaning and descaling the inner wall of the upper oil pipe of the hedging. Conventional well washing only flushes the pipe wall with water flow, and cannot thoroughly scrape off scale, sludge and other impurities on the pipe wall. The well washing operation effect does not meet the construction requirements. Utility Model Content

[0004] The main purpose of the utility model is to provide a well-washing scraper, which can effectively solve the problems in the background technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] The cam is secured to the outer surface of the sliding sleeve and is adapted to engage the sliding sleeve of the drive means and to engage the sliding sleeve of the drive means.

[0007] Preferably, the sliding shaft and the fixing sleeve are fixed by riveting with release pins, and 2-4 release pins are provided.

[0008] Preferably, the outer cylindrical surface of the sliding claw is provided with 12-20 axially uniformly distributed slits, the length of the slit is from the lower end surface of the sliding claw to the upper step end surface, the slit width is 2-4 mm, and the outer cylindrical surface of the sliding claw is designed with 6-12 external teeth.

[0009] The working principle of this utility model:

[0010] In the present invention, before being lowered into the wellbore, the sliding claws of the scraper are embedded in the annular cavity of the fixed sleeve and the fixed cap, and the sliding claws are in a retracted state. Since the maximum outer diameter of the sliding claws is smaller than the maximum outer diameter of the cone head, the sliding claws will not scrape the inner wall of the oil pipe during lowering, causing wear of the sliding claws. After the wellhead is opened, the scraper is lowered into the oil pipe and descends under its own weight. When descending to the casing packer, the scraper will not pass through the inner diameter of the packer center pipe because the inner diameter of the packer center pipe is smaller than the outer diameter of the cone head. After the cone head of the scraper strikes the end face of the packer center pipe, the cone head and the sliding shaft move upward under the reaction force, instantly shearing the release pin. At the same time, the upward movement of the sliding shaft drives the sliding claws and the fixed shaft upward. The fixed shaft ascends to the uppermost end face in the keyway of the fixed sleeve. At this time, the sliding claws slide out of the annular cavity of the fixed sleeve and the fixed cap and then expand due to elasticity, and the outer teeth of the sliding claws are in close contact with the inner wall of the oil pipe. During the well washing operation, a pump truck is used on the ground to pump the washing fluid into the wellbore from the casing. After reaching the bottom of the well, the washing fluid enters the oil pipe through the well washing device. When the washing fluid reaches the scraper, the scraper is pushed upward by the pressure and flow of the washing fluid. Because the sliding claws are made of spring steel and have elastic deformation properties after quenching, the outer teeth of the sliding claws are in close contact with the inner wall of the oil pipe. Each outer tooth scrapes the inner wall of the oil pipe while scraping. The scraped sludge, scale and other impurities are returned to the ground tank truck with the washing fluid. After scraping, the inner wall of the oil pipe is clean and smooth, and restored to the standard inner diameter of the oil pipe. After reaching the wellhead, the scraper enters the recovery device, and the washing fluid enters the tank truck through the pipeline, and the well washing operation is completed.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] At present, conventional well washing at oil fields is to pump washing fluid into the wellbore from the ground and return it to the tank truck through the oil pipe. The washing fluid only flushes the inner wall of the oil pipe, but does not really clean the oil sludge and scale flakes on the inner wall of the oil pipe. Because the oil pipe is in production for a long time underground, as the water quality deteriorates, the inner wall of the oil pipe will be scaled, resulting in a decrease in the inner diameter of the oil pipe. The scale flakes will not be flushed away during conventional well washing, so the conventional well washing operation cannot meet the construction operation requirements. Therefore, a well washing scraper is needed that can clean the scale flakes, oil sludge and other impurities on the inner wall of the oil pipe in a simple, efficient and safe manner during the well washing operation to meet the requirements of the well washing operation.

[0013] In the present invention, through the first test, after the scraper designed with nitrile rubber is lowered into the wellbore, the rubber will expand and adhere to the inner wall of the oil pipe as the temperature of the well fluid increases. After the well fluid is pumped in, the rubber is further deformed by the pressure. When it expands to a critical value, it will be blocked and stuck in the oil pipe. As the pumping pressure increases, the pressure in the section of oil pipe from the obstruction position to the wellhead increases, which increases the operation risk. Pulling out the pipe again also increases production costs. If a backwash operation is used to push the obstructed scraper back to the wellhead, the increased downhole pressure will increase the initial velocity of the scraper, and the instantaneous pressure release will cause a blowout accident. Therefore, the use of a rubber scraper for well washing operations is neither safe nor will it improve the well washing efficiency.

[0014] Through the second test, a sliding claw designed with spring steel material was selected. The outer cylindrical surface of the sliding claw was provided with 12-20 axially uniformly distributed slits. The slit length was from the lower end face of the sliding claw to the upper step end face, and the slit width was 2-4mm. The outer cylindrical surface of the sliding claw was designed with 6-12 external teeth. The slits were processed using a CNC electric spark wire cutting machine. After quenching treatment, the sliding claw had elastic deformation characteristics. The sliding claw was embedded in the annular cavity of the fixed sleeve and the fixed cap and was in a contracted state. The sliding claw slid out of the annular cavity of the fixed sleeve and the fixed cap and was in an open state.

[0015] Before well washing operation:

[0016] Before the scraper is lowered into the wellbore, a test instrument is lowered to measure and adjust the water volume. When it reaches 1,000 meters, it encounters resistance, preventing the test instrument from reaching the intended position for testing. This indicates that the inner wall of the tubing is contaminated with scale, sludge, and other impurities, which has reduced the inner diameter of the tubing and prevented the test instrument from passing smoothly. The scraper is lowered into the tubing by its own weight. When the scraper strikes the casing packer, the cone head and sliding shaft move upward to shear the release pin, while the sliding claw moves upward and opens to press against the inner wall of the tubing. At this point, the pre-well flushing operation is completed.

[0017] During well washing operation:

[0018] On the ground, a pump truck is used to pump the well washing fluid from the casing into the wellbore. After reaching the bottom of the well, the well washing fluid enters the oil pipe through the well washing device. When the well washing fluid reaches the scraper, the well washing fluid pressure and flow push the scraper upward. The outer teeth of the sliding claws are close to the inner wall of the oil pipe. Each outer tooth scrapes the inner wall of the oil pipe while scraping. The scraped sludge, scale and other impurities are returned to the ground tank truck with the well washing fluid. After scraping, the inner wall of the oil pipe is clean and smooth, and restored to the standard oil pipe inner diameter. After reaching the wellhead, the scraper enters the recovery device, and the well washing fluid enters the tank truck through the pipeline, and the well washing operation is completed.

[0019] After well washing operation:

[0020] The test instrument was lowered into the wellbore again to measure and adjust the water volume. The test instrument was able to reach the predetermined position smoothly for testing operations, indicating that the scale, sludge and other impurities on the inner wall of the oil pipe had been scraped off thoroughly and restored to the standard oil pipe inner diameter size, so the test instrument was able to pass smoothly. After the test instrument completed the operation, the oil pipe was lifted to the ground, and the measurement and adjustment construction was completed.

[0021] Two tests have proved that the utility model can completely scrape off scale, sludge and other impurities on the inner wall of the oil pipe. No additional large equipment is required during well washing, and no conventional well washing operation method needs to be changed. The scraper is put into the oil pipe before the conventional well washing operation. During well washing, the scraper can completely clean off scale, sludge and other impurities on the inner wall of the oil pipe. The inner diameter of the oil pipe after scraping is restored to the standard, and the test instrument can pass smoothly. Therefore, the use of the utility model for well washing operation is simple, efficient and safe, and can meet the construction operation requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the overall structure of a well-washing scraper of the utility model;

[0023] Figure 2 This is a schematic diagram of the sliding shaft structure of a well-washing scraper of the utility model;

[0024] Figure 3 This is an expanded view of the fixed sleeve structure of a well-washing scraper of the utility model;

[0025] Figure 4 This is a schematic diagram of the sliding claw structure of a well-washing scraper of the utility model;

[0026] In the figure: 1. Recovery head; 2. Sliding shaft; 3. Fixed sleeve; 4. Sliding claw; 5. Fixed cap; 6. Cone head; 7. Release pin; 8. Fixed shaft. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0028] like Figure 1-4As shown, a well washing scraper includes a recovery head 1, a sliding shaft 2, a fixed sleeve 3, a sliding claw 4, a fixed cap 5, a cone head 6, a release pin 7 and a fixed shaft 8. The outer surface of the sliding shaft 2 is installed with a fixed sleeve 3, and the outer surface of the fixed sleeve 3 is installed with a sliding claw 4 and a fixed cap 5. The outer cylindrical surface of the sliding shaft 2 and the sliding claw 4 is provided with a radially penetrating through hole. The fixed shaft 8 is installed in the through hole of the sliding shaft 2 and the sliding claw 4. The outer cylindrical surface of the fixed sleeve 3 is provided with a radially penetrating and symmetrically arranged keyway. The fixed shaft 8 can slide up and down in the keyway of the fixed sleeve 3. The fixed shaft 8 is at the uppermost of the keyway of the fixed sleeve 3. When the sliding claw 4 is in the open state, when the fixed shaft 8 is at the lowest end of the keyway of the fixed sleeve 3, the sliding claw 4 is embedded in the annular cavity of the fixed sleeve 3 and the fixed cap 5 and is in a contracted state. The recovery head 1 and the fixed sleeve 3 are connected by threads, the sliding shaft 2 and the cone head 6 are connected by threads, and the sliding shaft 2 and the fixed sleeve 3 are riveted and fixed by release pins 7. There are 2-4 release pins 7. The outer cylindrical surface of the sliding claw 4 is provided with 12-20 axially uniformly distributed slits. The length of the slit is from the lower end face of the sliding claw 4 to the upper step end face, the slit width is 2-4mm, and the outer cylindrical surface of the sliding claw 4 is designed with 6-12 external teeth.

[0029] Before going down the well, the sliding claw 4 of the scraper is embedded in the annular cavity of the fixing sleeve 3 and the fixing cap 5, and the sliding claw 4 is in a retracted state. Since the maximum outer diameter of the sliding claw 4 is smaller than the maximum outer diameter of the cone head 6, the sliding claw 4 will not scrape the inner wall of the oil pipe and cause wear of the sliding claw 4 when going down the well.

[0030] After the wellhead is opened, the scraper is put into the oil pipe. The scraper descends by its own weight. When it descends to the casing packer, since the inner diameter of the center pipe of the packer is smaller than the outer diameter of the cone head 6, the scraper will not pass through the inner diameter of the center pipe of the packer. After the cone head 6 of the scraper hits the end face of the center pipe of the packer, the cone head 6 and the sliding shaft 2 move upward under the reaction force, instantly shearing off the release pin 7. At the same time, the upward movement of the sliding shaft 2 drives the sliding claw 4 and the fixed shaft 8 upward. The fixed shaft 8 moves upward in the keyway of the fixed sleeve 3 to the uppermost end face. At this time, the sliding claw 4 slides out of the annular cavity of the fixed sleeve 3 and the fixed cap 5 and opens by elasticity. The outer teeth of the sliding claw 4 are close to the inner wall of the oil pipe.

[0031] During the well washing operation, a pump truck is used on the ground to pump washing fluid from the casing into the wellbore. After reaching the bottom of the well, the washing fluid enters the oil pipe through the well washing device. When the washing fluid reaches the scraper, the scraper is pushed upward by the pressure and flow of the washing fluid. Because the sliding claw 4 is made of spring steel and has elastic deformation characteristics after quenching, the outer teeth of the sliding claw 4 are in close contact with the inner wall of the oil pipe. Each outer tooth scrapes the inner wall of the oil pipe while scraping. The scraped sludge, scale and other impurities are returned to the ground tank truck with the washing fluid. The scraped inner wall of the oil pipe is clean and smooth, and restored to the standard oil pipe inner diameter. After reaching the wellhead, the scraper enters the recovery device, and the washing fluid enters the tank truck through the pipeline, and the well washing operation is completed.

Claims

1. A well-washing scraper, comprising a recovery head (1), a sliding shaft (2), a fixed sleeve (3), a sliding claw (4), a fixed cap (5), a cone head (6), a release pin (7) and a fixed shaft (8), characterized in that: The outer surface of the sliding shaft (2) is provided with a fixed sleeve (3), and the outer surface of the fixed sleeve (3) is provided with a sliding claw (4) and a fixed cap (5). The outer cylindrical surfaces of the sliding shaft (2) and the sliding claw (4) are provided with a radially penetrating through hole. The fixed shaft (8) is installed in the through hole of the sliding shaft (2) and the sliding claw (4). The outer cylindrical surface of the fixed sleeve (3) is provided with a radially penetrating and symmetrically arranged keyway. The fixed shaft (8) can slide up and down in the keyway of the fixed sleeve (3). When the fixed shaft (8) is at the uppermost end of the keyway of the fixed sleeve (3), the sliding claw (4) is in an open state. When the fixed shaft (8) is at the lowermost end of the keyway of the fixed sleeve (3), the sliding claw (4) is embedded in the annular cavity of the fixed sleeve (3) and the fixed cap (5) and is in a contracted state. The recovery head (1) and the fixed sleeve (3) are connected by threads, and the sliding shaft (2) and the cone head (6) are connected by threads.

2. A well-washing scraper according to claim 1, characterized in that: The sliding shaft (2) and the fixing sleeve (3) are riveted and fixed by release pins (7), and 2-4 release pins (7) are provided.

3. A well-washing scraper according to claim 1, characterized in that: The outer cylindrical surface of the sliding claw (4) is provided with 12-20 axially evenly distributed slits, the length of the slits is from the lower end surface of the sliding claw (4) to the upper step end surface, the slit width is 2-4 mm, and the outer cylindrical surface of the sliding claw (4) is designed with 6-12 external teeth.

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