Anti-pollution device for oil layer isolation

Abstract

The anti-pollution device is arranged in a shaft and located between a lifting tubular column and an oil production stratum, the oil layer is separated from working liquid in well washing, paraffin removal and other measure operations on the upper portion of the device through a leather cup assembly, in an oil field producing well, the oil layer is effectively protected, and long-term stable production of the oil well is guaranteed; when the anti-pollution device needs to be moved out of the oil well, crude oil in the upper space of the leather cup assembly can be prevented from being splashed to the ground through oil unloading operation of the oil unloading mandrel, the environment is protected, and meanwhile the well control risk caused by the upward swabbing effect of the anti-pollution device is avoided.

Description

Technical Field

[0001] This application relates to the field of oilfield lift technology, and in particular to a pollution prevention device for oil reservoir isolation. Background Technology

[0002] The information provided in this section is for the purpose of generally presenting the background of this disclosure. To the extent described in this section, the work of the currently named inventors and aspects of the description that may not constitute prior art at the time of filing are neither explicitly nor implicitly considered to be prior art of this disclosure.

[0003] Oilfield lift strings are a key piece of equipment used in oilfield extraction, primarily for lifting crude oil or natural gas from the bottom of the well to the surface for collection and transportation.

[0004] As oilfield development progresses, reservoir pressure gradually decreases. During operations such as pump inspection and dewaxing of the lift tubing, the well-killing and well-washing fluids cannot establish pressure balance within the wellbore, resulting in a large amount of fluid leaking into the formation. This not only contaminates the reservoir but also introduces well-killing and well control risks, affecting not only the long-term stable production of oil wells but also increasing the costs of oil and gas field development. Summary of the Invention

[0005] In view of the deficiencies in the prior art, this application provides a pollution prevention device for oil reservoir isolation to solve the problem of pollution caused by well washing operations in the prior art.

[0006] The above-mentioned objectives of this application are mainly achieved through the following technical solutions:

[0007] A contamination prevention device for oil reservoir isolation, the device being disposed within the wellbore and located between the lift string and the oil-producing formation, the contamination prevention device comprising:

[0008] The upper connector has one end for detachable connection to the lower part of the lifting column, and the upper connector has a working space that runs through both ends.

[0009] An oil unloading mandrel is detachably connected to the other end of the upper connector. The oil unloading mandrel has a cavity communicating with the working space inside, and multiple radially arranged through holes are provided on the side wall of the oil unloading mandrel.

[0010] A cup assembly is coaxially arranged at the end of the unloading mandrel away from the upper connector, and the cup assembly is used to cooperate with the wellbore, and restricts the communication between the upper space and the lower space of the cup assembly within the wellbore.

[0011] In an optional embodiment, the cup assembly includes a first mandrel, a second mandrel, and a plurality of cup portions. The first mandrel and the second mandrel are coaxially threaded together, and the first mandrel and the second mandrel are respectively provided with cavities communicating with the working space. The plurality of cup portions are coaxially arranged on the first mandrel and / or the second mandrel, and the cup portions have a working surface that contacts the wellbore.

[0012] In an optional embodiment, the cup portion is interference-fitted with the wellbore.

[0013] In an optional embodiment, the cup portion is provided with a deformation ring, the deformation ring has deformation recovery force, and the working surface is arranged on the outer wall of the deformation ring, the outer diameter of the deformation ring is larger than the inner diameter of the wellbore.

[0014] In an optional embodiment, the anti-pollution device further includes a sliding member, which is connected between the upper connector and the oil unloading spindle. The two ends of the sliding member can move closer to or further away from each other, so that the upper connector and the oil unloading spindle can move closer to or further away from each other.

[0015] In an optional embodiment, the sliding member includes a connecting mandrel and a connecting outer cylinder. The connecting mandrel is fixedly connected to the upper connector, and the connecting outer cylinder is fixedly connected to the oil unloading mandrel. The connecting mandrel and the connecting outer cylinder are coaxial and close to or far from each other.

[0016] In an optional embodiment, the connecting outer cylinder is provided with a sliding groove, one end of the connecting mandrel extends into the sliding groove and can reciprocate within the sliding groove along the axial direction of the connecting outer cylinder, and a limiting ring is provided in the sliding groove to restrict the connecting mandrel from disengaging.

[0017] In an optional embodiment, a flow connector and a sealing sleeve are detachably connected between the upper connector and the unloading mandrel. The flow connector is fixedly connected to the upper connector, and the sealing sleeve is fixedly connected between the flow connector and the unloading mandrel. The flow connector and the sealing sleeve are respectively provided with cavities communicating with the working space. The flow connector is circumferentially arranged with a plurality of radial through holes.

[0018] In an optional embodiment, the end of the cup assembly away from the unloading mandrel is provided with a detachable and fixed positioning mandrel. The positioning mandrel is fitted with a straightening sleeve, which has a plurality of radially penetrating positioning grooves. A locking block is movably provided between the positioning mandrel and the straightening sleeve. The locking block has a boss that can extend out of the positioning groove. The boss can cooperate with the wellbore to lock and restrict the descent of the anti-pollution device inside the wellbore.

[0019] In an optional embodiment, an elastic element is provided between the positioning mandrel and the locking block. The elastic element is used to push the locking block away from the positioning mandrel until the boss is engaged on the well shaft. The boss is provided with a guide slope so that when the anti-pollution device rises in the well shaft, the guide slope guides the boss to retract into the positioning groove. The straightening sleeve is provided with a plurality of radially penetrating tightening holes. A soluble pushing part is provided in the tightening hole. When the soluble pushing part is provided in the tightening hole, the soluble pushing part pushes the locking block and causes the boss to retract into the positioning groove.

[0020] Compared with the prior art, the advantages of this application are:

[0021] The anti-pollution device in this application is arranged inside the wellbore and located between the lift string and the oil-producing formation. The anti-pollution device includes an upper connector, an unloading mandrel, and a cup assembly. One end of the upper connector is detachably connected to the lower part of the lift string, and the upper connector has a working space extending through both ends. The unloading mandrel is detachably connected to the other end of the upper connector. The unloading mandrel has a cavity communicating with the working space, and its sidewall has multiple radially arranged through holes. The cup assembly is coaxially arranged at the end of the unloading mandrel away from the upper connector, and the cup assembly is used to cooperate with the wellbore, restricting the upper space of the cup assembly within the wellbore. The lower space is connected. During actual operation, the anti-pollution device is arranged inside the wellbore and located between the lifting tubing and the oil-producing formation. The cup assembly separates the oil layer from the working fluid used in well washing, dewaxing, and other operations above the device. In oilfield production wells, this effectively protects the oil layer, ensures long-term stable production, reduces oil well productivity loss, and improves economic efficiency. Moreover, when the anti-pollution device needs to be removed from the well, the oil unloading operation through the unloading mandrel ensures that the crude oil in the upper space of the cup assembly does not splash onto the ground. At the same time, it avoids well control risks caused by the upward pumping action of the anti-pollution device, thus protecting the environment. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A partial cross-sectional view of the anti-pollution device is provided for the embodiments of this application;

[0024] In the diagram: 100, upper connector; 200, oil unloading mandrel; 300, leather cup assembly; 301, first mandrel; 302, second mandrel; 303, leather cup part; 304, deformation ring; 400, sliding component; 401, connecting mandrel; 402, connecting outer cylinder; 403, sliding groove; 404, limiting ring; 501, flow short joint; 502, sealing sliding sleeve; 601, positioning mandrel; 602, straightening sleeve; 603, positioning groove; 604, locking block; 605, boss; 606, elastic component; 607, guide slope; 608, tightening hole. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that the description of these embodiments is intended to aid in understanding the invention, but does not constitute a limitation thereof. The specific structural and functional details disclosed herein are merely for describing exemplary embodiments of the invention. However, the invention can be embodied in many alternative forms and should not be construed as being limited to the embodiments described herein.

[0026] Pump inspection via lift tubing is a crucial operation in oilfield production, primarily used for inspecting, repairing, or replacing downhole pumps. This operation is essential for ensuring normal oilfield production and extending equipment lifespan.

[0027] Before commencing operations, conduct a safety inspection to ensure all equipment and tools are in good working order and prepare necessary equipment and tools, such as workover rigs, wellhead equipment, and tubing handling equipment.

[0028] Then, the lifting string (including sucker rod and pump) is gradually pulled out of the wellhead using a workover rig. During the pull-out process, the depth of the string and any abnormalities are recorded. The pulled-out string is then cleaned and inspected to check for wear, corrosion or damage. The pump is also inspected to assess its performance and condition and determine whether it needs repair or replacement.

[0029] Then, the repaired or replaced tubing is lowered back into the well, ensuring proper alignment to avoid jamming. The tubing and wellhead equipment are then connected at the wellhead. The pumping equipment is then started for a trial run to check the pump's operating status and the tubing's sealing. After the pump inspection is completed, the well's production is monitored to ensure normal operation.

[0030] Wax removal from lift tubing is an important maintenance activity in oilfield production, aimed at removing wax deposits from the tubing to maintain well flow efficiency and extend equipment life. Wax is a type of hydrocarbon found in crude oil that easily solidifies and deposits on the tubing wall when temperatures drop, obstructing well flow.

[0031] When performing wax removal operations on the lift string, stop production at the well, close the relevant valves, and ensure that there is no crude oil flow in the work area. Use a workover rig to gradually pull the lift string out of the wellhead to facilitate the wax removal operation. Use a hot wash truck to inject hot fluid (such as water or oil) into the string to dissolve and remove wax deposits. Then, use specialized wax removal tools, such as scrapers and brushes, to manually remove difficult-to-dissolve wax deposits. In some cases, it may be necessary to use an acidic solution to dissolve the wax deposits, which is usually done after hot washing. After wax removal, thoroughly inspect the string to ensure that the wax deposits have been removed.

[0032] The cleaned tubing string is lowered back into the well, ensuring proper alignment to prevent jamming. After the dewaxing operation is completed, the well is reopened to resume production. After the dewaxing operation is completed, the production status of the well is continuously monitored to ensure that the wax deposition problem is effectively controlled.

[0033] Dewaxing of lift tubing is a routine operation in oilfield maintenance, and it is of great significance for maintaining normal well production and improving economic efficiency. Regular dewaxing can reduce the impact of wax deposits on well production, extend equipment lifespan, and improve the overall production efficiency of the oilfield.

[0034] like Figure 1 As shown, Figure 1 A partial cross-sectional view of the anti-pollution device is provided for the embodiments of this application.

[0035] like Figure 1 As shown, an anti-fouling device for oil reservoir isolation is disposed within the wellbore and located between the lift string and the oil-producing formation. The anti-fouling device includes an upper connector 100, an unloading mandrel 200, and a cup assembly 300, wherein:

[0036] One end of the upper connector 100 is detachably connected to the lower part of the lifting column, and the upper connector 100 has a working space that runs through both ends.

[0037] The unloading mandrel 200 is detachably connected to the other end of the upper connector 100. The unloading mandrel 200 has a cavity communicating with the working space, and the side wall of the unloading mandrel 200 is provided with a plurality of radially arranged through holes.

[0038] The cup assembly 300 is coaxially arranged at the end of the unloading mandrel 200 away from the upper connector 100, and the cup assembly 300 is used to cooperate with the wellbore, and restricts the communication between the upper space and the lower space of the cup assembly 300 within the wellbore.

[0039] In an optional embodiment, the working principle of the anti-pollution device in this application is as follows: the anti-pollution device is arranged inside the wellbore and located between the lifting tubing and the oil-producing formation. The anti-pollution device includes an upper connector 100, an unloading mandrel 200, and a cup assembly 300. One end of the upper connector 100 is detachably connected to the lower part of the lifting tubing. The upper connector 100 has a working space that extends through both ends. The unloading mandrel 200 is detachably connected to the other end of the upper connector 100. The unloading mandrel 200 has a cavity communicating with the working space, and the side wall of the unloading mandrel 200 has multiple radially arranged through holes. The cup assembly 300 is coaxially arranged at the end of the unloading mandrel 200 away from the upper connector 100. The device is used in conjunction with the wellbore and restricts the communication between the upper and lower spaces of the cup assembly 300 within the wellbore. In actual operation, the anti-pollution device is arranged inside the wellbore and located between the lifting tubing and the oil-producing formation. The cup assembly 300 separates the oil layer from the working fluid used in well washing, dewaxing, and other operations above the device. In oilfield production wells, this effectively protects the oil layer, ensures long-term stable production, reduces oil well productivity loss, and improves economic efficiency. Moreover, when the anti-pollution device needs to be removed from the oil well, the oil unloading operation of the unloading mandrel 200 ensures that the crude oil in the upper space of the cup assembly 300 does not splash onto the ground. At the same time, it avoids well control risks caused by the upward pumping action of the anti-pollution device, thus protecting the environment.

[0040] like Figure 1 As shown, in an optional embodiment, the cup assembly 300 includes a first spindle 301, a second spindle 302, and a plurality of cup portions 303. The first spindle 301 and the second spindle 302 are coaxially threaded together, and the first spindle 301 and the second spindle 302 are respectively provided with cavities communicating with the working space. The plurality of cup portions 303 are coaxially arranged on the first spindle 301 and / or the second spindle 302. The cup portion 303 has a working surface that contacts the wellbore. The provision of multiple cup portions 303 is to maintain a better working space isolation effect, further preventing communication between the upper and lower spaces of the cup portion 303 in the wellbore. Each cup portion 303 contacts the inner wall of the wellbore through its working surface, further maintaining the reliability of the isolation during the operation process.

[0041] like Figure 1 As shown, in an optional embodiment, the cup portion 303 is interference-fitted with the wellbore to ensure a tighter connection between the cup portion 303 and the wellbore after assembly, so that the upper and lower spaces of the cup portion 303 within the wellbore maintain a more stable independent state, thereby improving the barrier effect in complex operating conditions.

[0042] It should be noted that when two diaphragm cups 303 are installed, the pressure difference that the diaphragm cup 303 can withstand is 27 MPa. In actual operation, the pressure that the diaphragm cup 303 can withstand is calculated using the following formula:

[0043] P 上 -P 下 =27MPa;

[0044] P 上 =P 液柱 -P 井口 ;

[0045] Where: P 上 For the upper space pressure of the leather cup, P 下 P represents the pressure in the lower space of the cup-shaped part 303, and this pressure is equal to the formation pressure. 液柱 P is the pressure generated by the gravity of the liquid column from the 303 section of the wellhead to the wellhead. 井口 The pressure for circulating the liquid column in the ground pump truck is adjusted according to the actual construction situation.

[0046] When performing well control operations with a working fluid having a relative density of 1, the following calculations are performed:

[0047] P 下 =P 地层 =20MPa

[0048] P 液柱 =1*9.8*2000 / 1000 = 19.6MPa

[0049] P 上 =27+P 下 =27 + 20 = 47 MPa

[0050] P 井口 =P 上 -P 液柱 =47-19.6=27.4MPa

[0051] The safe operating pressure at wellhead P is calculated to be 21.92 MPa based on a safety factor of 0.8.

[0052] The above calculations show that when the wellhead working pressure does not exceed 21.92 MPa, the working fluid in the well is completely isolated by the cup part 303 and cannot enter the formation, thus achieving the purpose of protecting the reservoir and preventing the working fluid from directly contacting the formation, contaminating the reservoir, and affecting production recovery and stable production.

[0053] like Figure 1As shown, in an optional embodiment, the cup portion 303 is provided with a deformation ring 304, the deformation ring 304 has deformation recovery force, and the working surface is arranged on the outer wall of the deformation ring 304, the outer diameter of the deformation ring 304 is larger than the inner diameter of the wellbore.

[0054] The deformation ring 304 is arranged on the cup portion 303, and the working surface for contacting the wellbore is located on the deformation ring 304. During operation, the working surface on the deformation ring 304 contacts the inner wall of the wellbore to ensure that the working surface is always reliably in contact with the inner wall of the wellbore. The deformation of the deformation ring 304 provides a stable barrier effect.

[0055] like Figure 1 As shown, in an optional embodiment, the anti-pollution device further includes a sliding member 400, which is connected between the upper connector 100 and the oil unloading spindle 200. The two ends of the sliding member 400 can move closer to or further away from each other, so that the upper connector 100 and the oil unloading spindle 200 can move closer to or further away from each other.

[0056] After the anti-pollution device and the lifting tubing enter the working state, the lifting tubing extracts crude oil from the formation and enters the oil production pump system. During the oil production process, the vibration generated by the fluid flow causes the anti-pollution device to be in a state of up-and-down creeping in the wellbore. At this time, the two ends of the sliding member 400 move by moving closer or further away from each other, thereby offsetting the friction force generated by the overall creeping of the anti-pollution device on the cup part 303, thereby increasing the service life of the cup part 303.

[0057] like Figure 1 As shown, in an optional embodiment, the sliding member 400 includes a connecting mandrel 401 and a connecting outer cylinder 402. The connecting mandrel 401 is fixedly connected to the upper connector 100, and the connecting outer cylinder 402 is fixedly connected to the oil unloading mandrel 200. The connecting mandrel 401 and the connecting outer cylinder 402 are coaxial and may be close to or far from each other. In actual operation, one end of the connecting mandrel 401 is relatively displaced within the connecting outer cylinder 402, which causes the relative distance between the upper connector 100 and the oil unloading mandrel 200 to change, so as to compensate for the creep displacement.

[0058] like Figure 1 As shown, in an optional embodiment, the connecting outer cylinder 402 is provided with a sliding groove 403, one end of the connecting mandrel 401 extends into the sliding groove 403 and can reciprocate within the sliding groove 403 along the axial direction of the connecting outer cylinder 402, and a limiting ring 404 is provided in the sliding groove 403 to restrict the connecting mandrel 401 from coming out.

[0059] One end of the connecting spindle 401 extends into the slide groove 403 and moves back and forth within the slide groove 403 under the guidance of the extension of the slide groove 403, so that the two ends of the sliding member 400 are close to or far apart from each other. The limiting ring 404 in the slide groove 403 provides displacement blocking and limits the travel of the connecting spindle 401, thus maintaining the reliability of the movement process.

[0060] like Figure 1 As shown, in an optional embodiment, a flow connector 501 and a sealing sleeve 502 are detachably connected between the upper connector 100 and the unloading mandrel 200. The flow connector 501 is fixedly connected to the upper connector 100, and the sealing sleeve 502 is fixedly connected between the flow connector 501 and the unloading mandrel 200. The flow connector 501 and the sealing sleeve 502 are respectively provided with cavities communicating with the working space. The flow connector 501 has multiple radial through holes arranged circumferentially. The flow connector 501, the sealing sleeve 502, and the unloading mandrel 200 form an unloading system, so that the crude oil in the wellbore flows into the lower wellbore or formation below the cup-shaped component through the unloading system of the flow connector 501, the sealing sleeve 502, and the unloading mandrel 200, thereby preventing pumping during the tubing string tripping process and reducing well control risks.

[0061] like Figure 1 As shown, in an optional embodiment, the end of the cup assembly 300 away from the oil unloading spindle 200 is provided with a detachable and fixed positioning spindle 601. The positioning spindle 601 is fitted with a straightening sleeve 602. The straightening sleeve 602 is provided with a plurality of radially penetrating positioning grooves 603. A locking block 604 is movably provided between the positioning spindle 601 and the straightening sleeve 602. The locking block 604 is provided with a boss 605 that can extend out of the positioning grooves 603. The boss 605 can cooperate with the wellbore to lock and restrict the descent of the anti-pollution device inside the wellbore.

[0062] like Figure 1 As shown, during assembly, the positioning mandrel 601 is pre-assembled under the cup assembly 300 and arranged in the wellbore along with the anti-pollution device. The locking block 604 extends out of the positioning groove 603, so that the boss 605 on the locking block 604 is engaged with the wellbore. At this time, the engagement between the boss 605 and the wellbore prevents the anti-pollution device and the positioning mandrel 601 from continuing to descend in the wellbore, so as to maintain the relative positional relationship during the operation, reduce the control difficulty, and improve the reliability of the operation.

[0063] like Figure 1As shown, in an optional embodiment, an elastic element 606 is provided between the positioning mandrel 601 and the locking block 604. The elastic element 606 is used to push the locking block 604 away from the positioning mandrel 601 until the boss 605 is engaged on the well shaft. The boss 605 is provided with a guide slope 607 so that when the anti-pollution device rises in the well shaft, the guide slope 607 guides the boss 605 to retract into the positioning groove 603. The straightening sleeve 602 is provided with a plurality of radially penetrating tightening holes 608. A soluble pushing part is provided in the tightening hole 608. When the soluble pushing part is provided in the tightening hole 608, the soluble pushing part pushes the locking block 604 and causes the boss 605 to retract into the positioning groove 603.

[0064] The elastic element 606 provides the power for the locking block 604 to move outward toward the positioning groove 603 and prevents the elastic element 606 from retracting into the positioning groove 603 under certain vibration, further maintaining the stable locking relationship between the boss 605 and the well shaft. Furthermore, as the positioning mandrel 601 rises, the guide slope 607 on the boss 605 interacts with the well shaft, allowing the boss 605 to release its abutment relationship with the well shaft. The boss 605 can be pushed into the positioning groove 603, maintaining smooth upward operation. To ensure the positioning mandrel 601 can smoothly descend within the well shaft... At the target position, the soluble jacking part is assembled in the tightening hole 608, and the soluble jacking part pushes the locking block 604 to keep the boss 605 inside the positioning groove 603. This prevents the boss 605 from protruding during the descent of the positioning mandrel 601. Before the positioning mandrel 601 reaches the target position, the boss 605 is prevented from being tightly fitted with the wellbore. During actual operation, the soluble jacking part is dissolved under the action of high-temperature oil. At this time, the elastic element 606 can push the locking block 604 and make the boss 605 protrude from the positioning groove 603 to engage with the wellbore, thus improving the convenience of operation.

[0065] It should be understood that the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit, without departing from the scope of the exemplary embodiments of the invention.

[0066] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this article describes another relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after it are in an "or" relationship.

[0067] It should be understood that in the description of this invention, the terms "upper," "vertical," "inner," "outer," etc., indicate the orientation or positional relationship as commonly placed when the disclosed product is used, or the orientation or positional relationship commonly understood by those skilled in the art. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0068] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" 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 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 based on the specific circumstances.

[0069] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” “containing,” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, and do not exclude the presence or addition of one or more other features, quantities, steps, operations, units, components, and / or combinations thereof.

[0070] Specific details are provided in the following description to provide a complete understanding of the exemplary embodiments. However, those skilled in the art will understand that the exemplary embodiments can be implemented without these specific details. In other embodiments, well-known processes, structures, and techniques may be omitted in the depiction of non-essential details to avoid obscuring the exemplary embodiments.

[0071] The above are merely specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

[0072] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art.

Claims

1. A pollution prevention device for oil layer isolation, characterized in that, The anti-pollution device is installed inside the wellbore and located between the lift string and the oil-producing formation. The anti-pollution device includes: The upper connector has one end for detachable connection to the lower part of the lifting column, and the upper connector has a working space that runs through both ends. An oil unloading mandrel is detachably connected to the other end of the upper connector. The oil unloading mandrel has a cavity communicating with the working space inside, and multiple radially arranged through holes are provided on the side wall of the oil unloading mandrel. A cup assembly is coaxially arranged at the end of the unloading mandrel away from the upper connector, and the cup assembly is used to cooperate with the wellbore, and restricts the communication between the upper space and the lower space of the cup assembly within the wellbore.

2. The anti-pollution device for oil layer isolation as described in claim 1, characterized in that: The cup assembly includes a first mandrel, a second mandrel, and a plurality of cup portions. The first mandrel and the second mandrel are coaxially threaded together, and the first mandrel and the second mandrel are respectively provided with cavities communicating with the working space. The plurality of cup portions are coaxially arranged on the first mandrel and / or the second mandrel, and the cup portions have a working surface that contacts the wellbore.

3. The anti-pollution device for oil layer isolation as described in claim 2, characterized in that: The cup portion is interference-fitted with the wellbore.

4. The anti-pollution device for oil layer isolation as described in claim 2, characterized in that: The cup portion is provided with a deformation ring, which has deformation recovery force, and the working surface is arranged on the outer wall of the deformation ring. The outer diameter of the deformation ring is larger than the inner diameter of the wellbore.

5. The anti-pollution device for oil layer isolation as described in claim 1, characterized in that: The anti-pollution device also includes a sliding member, which is connected between the upper connector and the oil unloading spindle. The two ends of the sliding member can move closer to or further away from each other, so that the upper connector and the oil unloading spindle can move closer to or further away from each other.

6. The anti-pollution device for oil layer isolation as described in claim 5, characterized in that: The sliding component includes a connecting mandrel and a connecting outer cylinder. The connecting mandrel is fixedly connected to the upper connector, and the connecting outer cylinder is fixedly connected to the oil unloading mandrel. The connecting mandrel and the connecting outer cylinder are coaxial and may be close to or far from each other.

7. The anti-pollution device for oil layer isolation as described in claim 6, characterized in that: The connecting outer cylinder is provided with a sliding groove, one end of the connecting mandrel extends into the sliding groove and can slide back and forth in the sliding groove along the axial direction of the connecting outer cylinder, and a limiting ring is provided in the sliding groove to prevent the connecting mandrel from coming out.

8. The anti-pollution device for oil layer isolation as described in claim 1, characterized in that: A flow connector and a sealing sleeve are detachably connected between the upper connector and the unloading mandrel. The flow connector is fixedly connected to the upper connector, and the sealing sleeve is fixedly connected between the flow connector and the unloading mandrel. The flow connector and the sealing sleeve are respectively provided with cavities that communicate with the working space. The flow connector has multiple radial through holes arranged circumferentially.

9. The anti-pollution device for oil layer isolation as described in claim 1, characterized in that: The end of the cup assembly away from the unloading mandrel is provided with a detachable and fixed positioning mandrel. The positioning mandrel is fitted with a straightening sleeve, which has multiple radially penetrating positioning grooves. A locking block is movably provided between the positioning mandrel and the straightening sleeve. The locking block has a boss that can extend out of the positioning groove. The boss can cooperate with the wellbore to lock and restrict the descent of the anti-pollution device inside the wellbore.

10. The anti-pollution device for oil layer isolation as described in claim 9, characterized in that: An elastic element is provided between the positioning mandrel and the locking block. The elastic element is used to push the locking block away from the positioning mandrel until the boss is engaged on the well shaft. The boss is provided with a guide slope so that when the anti-pollution device rises in the well shaft, the guide slope guides the boss to retract into the positioning groove. The straightening sleeve is provided with multiple radially penetrating tightening holes. A soluble pushing part is provided in the tightening hole. When the soluble pushing part is provided in the tightening hole, the soluble pushing part pushes the locking block and causes the boss to retract into the positioning groove.

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