A self-cooling single screw pump for oil production

Abstract

This invention relates to the field of oil production technology, and more particularly to a self-cooled single-screw pump for oil production, comprising: an oil delivery mechanism, including a rotor that rotates along the oil delivery direction to provide oil suction power and a stator connected to the rotor to form a closed oil delivery channel; and a self-cooling mechanism that absorbs heat from the stator to cool the oil flowing inside the stator bushing, including a first cooling channel and a second cooling channel connected to the stator bushing and mutually cooperating to provide a cooling circulation space for the oil, wherein the relative spatial configuration of the first cooling channel and the second cooling channel is a double-helix structure. This invention improves the self-heating performance of the rubber stator of the single-screw pump, improves the uniformity of the rubber wall thickness and working performance of the screw pump stator, and avoids the hazards caused by heat accumulation effect and uneven wall thickness of the rubber stator.

Description

Technical Field

[0001] This invention relates to the field of oil production technology, and in particular to a self-cooling single screw pump for oil production. Background Technology

[0002] In existing technology, the single-screw pump for oil extraction is a mechanical device used in oil production. It utilizes the rotational motion of a single screw to lift crude oil. The main advantages of this pump are its simple structure, stable operation, convenient maintenance, and adaptability to oil wells with high viscosity and high sand content. A closed cavity is formed between the screw and the pump casing of the single-screw pump. As the screw rotates, oil is continuously drawn in and discharged. The single-screw pump combines the technical advantages of both positive displacement pumps and centrifugal pumps. It has a simple structure, low initial investment, can continuously lift media, has a stable load during operation, low losses, and high efficiency. It is one of the most energy-efficient and efficient mechanical oil extraction methods and is widely used in oilfields across China. Single-screw pumps are typically made of metal to withstand the harsh downhole working environment. The pump can be driven electrically or hydraulically. In an electric drive, the motor drives the screw to rotate through a reducer; in a hydraulic drive, the pressure of the downhole fluid is used to drive the screw. To improve oil production efficiency, the design of single screw pumps is constantly being optimized, including improving the geometry of the screw and pump casing, enhancing the corrosion resistance and wear resistance of materials, and optimizing pump performance.

[0003] Chinese Patent Publication No. CN102434458A discloses a double-headed single-screw pump with a 2 / 3 profile suitable for oilfield production. The pump body is characterized by a 2 / 3 profile double-headed single-screw pump body, wherein the surface of the double-headed helical rotor is uniformly coated with a nylon layer, and the stator is a die-cast metal stator. Therefore, the double-headed single-screw pump with a 2 / 3 profile suitable for oilfield production suffers from problems such as decreased pump performance due to rotor friction causing stator temperature rise, and decreased pump stability due to gas intake at the stator inlet. Summary of the Invention

[0004] Therefore, the present invention provides a self-cooling single screw pump for oil production, which overcomes the problems of deteriorated performance and premature product failure caused by heat accumulation in the thicker parts of the rubber stator during the operation of the screw pump in the prior art.

[0005] To achieve the above objectives, the present invention provides a self-cooled single-screw pump for oil production, comprising:

[0006] An oil production and delivery mechanism includes a rotor that provides oil suction power by rotating in the direction of oil delivery and a stator connected to the rotor to form a closed oil delivery channel with the rotor. The stator includes a stator bushing that collects oil by cooperating with the rotor and a stator outer tube connected to the stator bushing to support the stator bushing.

[0007] The self-cooling mechanism, which is connected to the stator, cools the oil flowing inside the stator bushing by absorbing heat from the stator. It includes a first cooling channel and a second cooling channel connected to the stator bushing and cooperating with each other to provide a cooling circulation space for the oil. The relative spatial configuration of the first cooling channel and the second cooling channel is a double helix structure.

[0008] Furthermore, the pitch of the first cooling channel and the second cooling channel are equal.

[0009] Furthermore, the pitch of the first cooling channel or the second cooling channel is twice the pitch of the stator bushing.

[0010] Furthermore, the midpoints of the first cooling channel and the second cooling channel are equidistant on the cross-section along the oil inlet direction.

[0011] Furthermore, the first cooling channel includes a plurality of external connecting holes and an internal connecting hole disposed on the suction end of the stator for drawing in the cooling oil;

[0012] The second cooling channel has the same internal structure as the first cooling channel.

[0013] Furthermore, a single external connecting hole is provided on the stator outer tube to discharge the cooling oil to the area outside the stator outer tube.

[0014] Furthermore, the number of external connecting holes is positively correlated with the pitch of the stator bushing.

[0015] Furthermore, the distance between any two adjacent external connecting holes on the first cooling channel and the second cooling channel is the same as the projected distance on the centerline of the stator.

[0016] Furthermore, the rotor is also used to draw the cooling oil into the closed oil delivery channel when the cooling oil flows from the outer connecting hole into the cooling channel and out through the inner connecting port, and merges with the oil in the stator's suction oil area.

[0017] Furthermore, during the meshing process between the rotor and the stator, the cooling channel is circulated and compressed to transport cooling oil from the outer connecting hole to the inner connecting hole.

[0018] Furthermore, during the periodic rotational meshing process, the rotor and the stator cause oil to be repeatedly drawn in and discharged through the first cooling channel and the second cooling channel to dissipate heat from the stator.

[0019] Furthermore, the stator is also used to form a vacuum space between the outer wall of the rotor and the inner wall of the stator bushing during the rotation of the rotor, so that the oil flows in the direction of oil delivery.

[0020] Furthermore, the stator bushing is made of rubber.

[0021] Compared with the prior art, the beneficial effects of the present invention are that the system of the present invention, by setting up an oil production and transportation mechanism and a self-cooling mechanism, addresses the issue that the uneven thickness of the stator inner wall causes heat generation and temperature rise within the stator, making it difficult for the stator to dissipate heat. By setting up a cooling channel in the stator bushing, the uniformity of the stator wall thickness of the single screw pump is improved, thereby further improving the working performance of the single screw pump.

[0022] Furthermore, the system of the present invention, by setting up a first cooling channel and a second cooling channel, addresses the issue that, due to the uneven thickness of the rubber during the casting of the stator bushing and the fact that rubber is a poor conductor of heat, the heat generated by the rotor operation causes a higher temperature rise in the thicker rubber sections. In addition, the swelling of the medium in the thicker rubber sections is also greater, which significantly increases the interference fit between the stator and rotor, and consequently increases the friction and frictional heat generated between the stator and rotor, leading to a decrease in system efficiency. By circling and setting up the first and second cooling channels inside the stator bushing, the stator is continuously cooled, thereby improving the working stability of the single screw and the uniformity of the wall thickness of the rubber stator bushing.

[0023] Furthermore, the system of the present invention, by setting an internal connecting hole and an external connecting hole group, realizes the flow of oil circuit and continuous heat absorption and dissipation when the rotor is working. The cooling oil enters through the external connecting hole, absorbs heat on the stator bushing in the cooling channel, and is discharged through the external connecting hole to dissipate heat. This helps to exchange the cooling oil in the cooling channel with the collected oil, thereby improving the heat dissipation performance of the stator.

[0024] Furthermore, the system described in this invention sets up a cooling channel, which forms a loop with the external area. During operation, the rotor squeezes the cooling oil, which flows up and down in the cooling channel and absorbs heat at different positions in the stator bushing. After absorbing heat, the cooling oil flows through the cooling channel and merges with the oil at the stator suction end, carrying away the heat. This enhances the heat dissipation performance of the self-cooling mechanism and further enhances the working performance of the single screw pump.

[0025] Furthermore, the system of the present invention increases the flow length of the cooling oil in the channel by setting a double helix structure for the cooling channel, prolongs the contact time between the coolant and the channel wall, which helps to improve the heat exchange efficiency. Compared with a straight channel, it can also reduce sharp turns and sudden changes in the flow, thereby reducing the flow resistance of the fluid, reducing the energy consumption of the pump, and realizing the enhanced working performance of the single screw pump. Attached Figure Description

[0026] Figure 1 This is an overall structural diagram of a self-cooled single-screw oil pump according to an embodiment of the present invention;

[0027] Figure 2 This is another structural view of the self-cooled single screw pump for oil production according to an embodiment of the present invention;

[0028] Figure 3 This is a structural diagram of the external communication hole of a self-cooled single-screw oil pump according to an embodiment of the present invention;

[0029] Figure 4 This is a structural diagram of the cooling channel of a self-cooled oil extraction single screw pump according to an embodiment of the present invention;

[0030] Figure 5 This is a structural diagram of the cooling channel with a non-circular cross-section of a self-cooled oil extraction single screw pump according to an embodiment of the present invention;

[0031] Explanation of reference numerals: 1-Rotor, 21-External connecting hole of the first cooling channel, 22-External connecting hole of the second cooling channel, 31-Internal connecting hole of the first cooling channel, 32-Internal connecting hole of the second cooling channel, 4-Outer stator tube, 5-Stator bushing, 6-First cooling channel, 7-Second cooling channel, 8-Temperature sensor, 9-Inner wall of stator bushing, 10-Outer wall of rotor. Detailed Implementation

[0032] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0033] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0034] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0035] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] Please see Figure 1 , Figure 2 , Figure 3 , Figure 4 as well as Figure 5 As shown, these are respectively the overall structural diagram, another angle structural diagram, the external connecting hole structural diagram, the cooling channel structural diagram, and another form of cooling channel structural diagram of the self-cooled oil production single screw pump of the present invention.

[0037] Example 1: This invention provides a self-cooled single-screw pump for oil production, comprising:

[0038] An oil production and transportation mechanism includes a rotor 1 that provides oil suction power by rotating in the direction of oil transportation and a stator connected to the rotor 1 to form a closed oil transportation channel with the rotor 1. The stator includes a stator bushing 5 that cooperates with the rotor 1 to collect oil and an outer stator tube 4 connected to the stator bushing 5 to support the stator bushing 5.

[0039] The self-cooling mechanism, which is connected to the stator, cools the oil flowing inside the stator bushing 5 by absorbing heat from the stator. It includes a first cooling channel 6 and a second cooling channel 7 connected to the stator bushing 5 and cooperating with each other to provide a cooling circulation space for the oil. The relative spatial configuration of the first cooling channel 6 and the second cooling channel 7 is a double helix structure.

[0040] Specifically, the working process of the self-cooled single-screw pump of this invention is as follows: Oil enters the stator suction port through the upper external connecting hole, coolant channel, and internal connecting hole, where it merges with the produced fluid from the lower part of the pump and is lifted to the ground by the screw pump. Simultaneously, during the meshing process between the rotor 1 and the stator, the liquid in the coolant channel is circulated and squeezed, flowing up and down: upwards through the external connecting hole to form a connecting passage with the outside of the stator outer tube 4, and downwards through the internal connecting hole to connect with the stator suction port, forcibly dissipating heat from the stator rubber. This repeated process of oil being drawn in and discharged through the coolant channel to dissipate heat from the stator is performed automatically and repeatedly during the periodic rotation and meshing of the rotor 1 and the stator, thereby preventing heat accumulation and temperature rise in the stator rubber.

[0041] In practice, the system of the present invention, by setting up an oil production and transportation mechanism and a self-cooling mechanism, addresses the issue that the uneven thickness of the stator inner wall causes heat accumulation and temperature rise within the stator, making it difficult for the stator to dissipate heat. By setting up a cooling channel inside the stator bushing 5, the uniformity of the stator wall thickness of the single screw pump is improved, thereby further enhancing the working performance of the single screw pump.

[0042] Specifically, the pitch of the first cooling channel 6 and the second cooling channel 7 are equal.

[0043] Specifically, the pitch of the first cooling channel 6 or the second cooling channel 7 is twice the pitch of the stator bushing 5.

[0044] Specifically, the midpoints of the first cooling channel 6 and the second cooling channel 7 are equidistant from each other on the cross-section along the oil inlet direction.

[0045] Specifically, the cross-sectional shape of the cooling channel can be set to circular or non-circular, as long as the function can be achieved.

[0046] In practice, the system of the present invention, by setting up a first cooling channel 6 and a second cooling channel 7, addresses the issue that, due to the uneven thickness of the rubber during the casting of the stator bushing 5 and the fact that rubber is a poor conductor of heat, the heat generated by the rotor 1 during operation causes a higher temperature rise in the thicker rubber sections. In addition, the swelling of the medium in the thicker rubber sections is also greater, which significantly increases the interference between the stator and rotor, and consequently increases the friction and frictional heat generated between the stator and rotor, leading to a decrease in system efficiency. By using the first cooling channel 6 and the second cooling channel 7 to continuously dissipate heat from the stator inside the stator bushing 5, the working stability of the single screw rod and the uniformity of the wall thickness of the rubber stator bushing 5 are improved.

[0047] Specifically, the first cooling channel 6 includes a plurality of external connecting holes and an internal connecting hole disposed on the suction end of the stator for sucking in the cooling oil;

[0048] The second cooling channel 7 has the same internal structure as the first cooling channel 6.

[0049] Specifically, the first cooling channel 6 is provided with a plurality of external connecting holes 21 and a first cooling channel 6 internal connecting hole 31, and the second cooling channel 7 is provided with a plurality of external connecting holes 22 and a second cooling channel 7 internal connecting hole 32.

[0050] Specifically, a single external connecting hole is provided on the stator outer tube 4 to discharge the cooling oil to the area outside the stator outer tube 4.

[0051] Specifically, the number of external connecting holes is positively correlated with the pitch of the stator bushing 5.

[0052] Specifically, the distance between any two adjacent external connecting holes on the first cooling channel 6 and the second cooling channel 7 is the same as the projected distance on the centerline of the stator.

[0053] In practice, the pitch of the stator bushing 5 is positively correlated with the number of external connecting holes. For example, when the pitch of the stator bushing 5 is less than 200mm, the number of external connecting holes on a cooling channel is set to 1-3. When the pitch of the stator bushing 5 is 200mm-300mm, the number of external connecting holes on a cooling channel is set to 4-6. When the pitch of the stator bushing 5 exceeds 300mm, the number of external connecting holes on a cooling channel increases by 2-4 for every 100mm exceeding 300mm. The specific number of external connecting holes on a cooling channel is adjusted appropriately according to the stator length.

[0054] In practice, the system of the present invention, by setting an internal connecting hole and an external connecting hole group, enables the oil circuit to circulate and continuously absorb and dissipate heat when the rotor 1 is working. The cooling oil enters through the external connecting hole, absorbs heat on the stator bushing 5 in the cooling channel, and is discharged through the external connecting hole to dissipate heat. This helps to exchange the cooling oil in the cooling channel with the collected oil, thereby improving the heat dissipation performance of the stator.

[0055] Specifically, the rotor 1 is also used to draw the cooling oil into the closed oil delivery channel when the cooling oil flows from the outer connecting hole into the cooling channel and out through the inner connecting port, and merges with the oil in the stator's suction oil area.

[0056] Specifically, during the meshing process between the rotor 1 and the stator, the cooling channel is circulated and compressed to transport cooling oil from the outer connecting hole to the inner connecting hole.

[0057] Specifically, during the periodic rotation and meshing process of the rotor 1 and the stator, oil is repeatedly drawn in and discharged through the first cooling channel 6 and the second cooling channel 7 to dissipate heat from the stator.

[0058] Specifically, the stator is also used to form a vacuum space between the outer wall 12 of the rotor and the inner wall 11 of the stator bushing during the rotation of the rotor 1, so that the oil flows in the direction of oil delivery.

[0059] Specifically, the stator bushing 5 is made of rubber.

[0060] Example 2: Based on Example 1, Example 2 of the present invention further includes a temperature sensor 8, which is connected to the stator and the self-cooling mechanism respectively, for detecting the temperature at the contact position between the stator outer tube 4 and the stator bushing 5;

[0061] The controller is connected to the temperature sensor 8 and the rotor 1 respectively, and is used to determine the operating stability of the rotor 1 based on the temperature difference of the stator bushing 5, so as to determine whether to adjust the speed of the rotor 1, and after the single screw pump stops working, to determine the degree of friction between the stator bushing 5 and the rotor 1 based on the temperature drop rate of the stator bushing 5.

[0062] In practice, a preferred embodiment of the controller is a small microcontroller.

[0063] Specifically, for a single temperature sensor 8, it is disposed on the inner wall of the stator outer tube 4 to detect the corresponding temperature of the stator bushing 5 in the area where the single temperature sensor 8 is located; several rings of the temperature sensor 8 are equally spaced on the inner wall of the stator outer tube 4, and the number of temperature sensors 8 per ring is determined according to the diameter of the stator outer tube 4.

[0064] Specifically, the temperature sensors 8 of a single turn are distributed at equal intervals along the diameter of the stator outer tube 4.

[0065] In practice, the number of temperature sensors 8 per turn is positively correlated with the diameter of the stator outer tube 4. For example, when the diameter of the stator outer tube 4 is 150mm, the number of temperature sensors 8 per turn is set to 4; when the diameter of the stator outer tube 4 is 200mm, the number of temperature sensors 8 per turn is set to 5.

[0066] Specifically, the controller is connected to the temperature sensor 8 to obtain the temperature of the stator bushing 5, calculate the temperature difference of the stator bushing 5 based on the average temperature of the stator bushing 5 per unit time, and if the temperature difference is greater than a preset difference, it is determined that the operating stability of the rotor 1 does not meet the requirements, and the speed of the rotor 1 is adjusted.

[0067] Specifically, the speed adjustment range of rotor 1 is positively correlated with the temperature difference.

[0068] Specifically, the temperature difference is the difference between the temperature of the stator bushing 5 and the average temperature of the stator bushing 5 per unit time.

[0069] Specifically, the general range of the preset difference is [4℃, 6℃].

[0070] Preferably, the preferred embodiment for the preset difference amount is 5°C.

[0071] In practice, when the difference between the temperature difference and the preset difference is within 1℃, the speed of rotor 1 increases to 1.2 times the original speed; when the difference between the temperature difference and the preset difference exceeds 1℃, the speed of rotor 1 increases by 8 rpm for every 1℃ increase. For example, if the temperature difference is 7℃ and the current speed of rotor 1 is 120 rpm, the speed of rotor 1 increases to 120 rpm × 1.2 + 8 rpm = 152 rpm.

[0072] In practice, by adjusting the rotor speed, the accumulation of impurities in the cooling oil in the cooling channel leads to frictional heat generation in the stator bushing 5 and reduced operating stability of the rotor 1. By initially adjusting the rotor speed to reduce the accumulation of impurities in the cooling channel, the operating stability of the rotor 1 is improved, and the stator heat dissipation performance is further enhanced.

[0073] Specifically, the controller is connected to the temperature sensor 8, which determines that the friction between the stator bushing 5 and the rotor 1 does not meet the requirements if the temperature drop rate of the stator bushing 5 is greater than the preset rate after the single screw pump stops working.

[0074] Specifically, the temperature decrease rate is the ratio of the difference between the temperature of the stator bushing 5 at the beginning of a unit time and the temperature of the stator bushing 5 at the end of a unit time to the unit time.

[0075] Specifically, the preset rate is generally taken in the range of [4℃ / min, 6℃ / min].

[0076] In practice, the preferred embodiment of the preset rate is 5°C / min.

[0077] In practice, the system of the present invention improves the working performance of the single screw pump by setting a preset rate. Since there is wear causing local temperature rise after the single screw pump stops working, resulting in a rapid temperature drop rate, it is determined that there is abnormal wear between the stator bushing 5 and the rotor 1. By determining whether the degree of friction between the stator bushing 5 and the rotor 1 meets the requirements, the system improves the working performance of the single screw pump.

[0078] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A self-cooled single-screw pump for oil production, characterized in that, include: An oil production and delivery mechanism includes a rotor that provides oil suction power by rotating in the direction of oil delivery and a stator connected to the rotor to form a closed oil delivery channel with the rotor. The stator includes a stator bushing that collects oil by cooperating with the rotor and a stator outer tube connected to the stator bushing to support the stator bushing. The self-cooling mechanism, which is connected to the stator, cools the oil flowing inside the stator bushing by absorbing heat from the stator. It includes a first cooling channel and a second cooling channel connected to the stator bushing and cooperating with each other to provide a cooling circulation space for the oil. The relative spatial configuration of the first cooling channel and the second cooling channel is a double helix structure. The first cooling channel includes several external connecting holes and an internal connecting hole disposed on the suction end of the stator for drawing in cooling oil. The second cooling channel has the same internal structure as the first cooling channel; The rotor is also used to draw the cooling oil into the closed oil delivery channel when the cooling oil flows from the outer connecting hole into the cooling channel and out through the inner connecting hole and merges with the oil in the stator's oil suction area. During the meshing process between the rotor and the stator, the cooling channel is circulated and compressed, causing the cooling oil to be transported from the outer connecting hole to the inner connecting hole.

2. The self-cooled single-screw pump for oil production according to claim 1, characterized in that, The pitch of the first cooling channel and the second cooling channel are equal.

3. The self-cooled single-screw pump for oil production according to claim 2, characterized in that, The pitch of the first cooling channel or the second cooling channel is twice the pitch of the stator bushing.

4. The self-cooled single-screw pump for oil production according to claim 3, characterized in that, The midpoints of the first cooling channel and the second cooling channel are equidistant on the cross-section along the oil inlet direction.

5. The self-cooled single-screw pump for oil production according to claim 1, characterized in that, The number of external connecting holes is positively correlated with the pitch of the stator bushing.

6. The self-cooled single-screw pump for oil production according to claim 5, characterized in that, The distance between any two adjacent external connecting holes on the first cooling channel and the second cooling channel is the same as the projected distance on the centerline of the stator.

7. The self-cooled single-screw pump for oil production according to claim 6, characterized in that, During the periodic rotation and meshing process, the rotor and the stator cause oil to be repeatedly drawn in and discharged through the first cooling channel and the second cooling channel to dissipate heat from the stator.

8. The self-cooled single-screw pump for oil production according to claim 7, characterized in that, The stator is also used to create a vacuum space between the outer wall of the rotor and the inner wall of the stator bushing during the rotation of the rotor, so that the oil can flow in the direction of oil delivery.

9. The self-cooled single-screw pump for oil production according to claim 8, characterized in that, The stator bushing is made of rubber.

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