Self-cleaning negative pressure sand washing tool and using method

Abstract

The invention discloses a self-cleaning negative-pressure sand washing tool and a using method. The negative-pressure sand washing tool comprises a connecting outer cylinder, a connecting inner cylinder, a flow channel switching mechanism, a jet pump mechanism and a jet unblocking mechanism. The switching shaft seat is connected to the lower end of the connecting inner cylinder; a switching sliding groove is formed in the outer side wall of the switching shaft base in the circumferential direction. The jet pump mechanism comprises a bypass base, a sand inlet formed in the bypass base and a negative pressure sand suction tool. Blind hole channels and through hole channels are evenly formed in the bypass base in the circumferential direction. The blind hole channel is arranged corresponding to the sand inlet, and the through hole channel is communicated with the jet flow unblocking mechanism; the switching sliding sleeve can compress the elastic piece under the action of fluid in the fluid pumping-in channel, vertically and downwards move along the switching sliding groove and circumferentially rotate in the preset direction at the same time till the switching sliding sleeve abuts against the bypass base, and therefore the fluid pumping-in channel communicates with the blind hole channel or the through hole channel. According to the invention, the underground self-cleaning function can be realized, and the sand inlet is prevented from being blocked.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field downhole operation, in particular to a self-cleaning negative pressure sand washing tool and a use method thereof. BACKGROUND

[0002] In the operation process of a low-pressure oil and gas well, the sand outflow of the low-pressure oil and gas well blocks the wellbore, and because the liquid level of the wellbore is lower than the height of the wellhead, the conventional water jet sand washing technology cannot flow back the blockage to the ground. The main technical means for sand washing and blockage removal of the low-pressure oil and gas well in China is the foam sand washing technology and the Venturi sand washing technology. The foam sand washing technology has high requirements for the composition of the wellbore liquid, and needs to be matched with devices such as liquid nitrogen and pump trucks, and has high comprehensive operation cost. The Venturi sand washing technology has low construction cost, but has low operation efficiency.

[0003] In view of the above technical difficulties, various negative pressure sand washing technologies have been researched and applied in China. The technical principle is to pump the power liquid into the jet pump inside the negative pressure sand washing tool through the operation string, form a negative pressure suction effect, suck the debris or sand particles in the wellbore into the operation pipe, flow back the sand particles to the ground from the operation string, and form a pumping and flow-back circulation channel in the operation string, which does not flow back to the ground from the wellbore such as casing or tubing, and is not affected by the liquid level in the wellbore of the low-pressure oil and gas well. In view of the problems such as sand blockage and sand burying in thick oil wells, gas wells and other low-pressure wells, the negative pressure sand washing can effectively solve the problem that the debris in the wellbore cannot be flowed back to the ground. SUMMARY

[0004] In order to solve the problem of sand inlet blockage and achieve the purpose of self-cleaning of the negative pressure sand washing tool, the present application provides a self-cleaning negative pressure sand washing tool and a use method thereof.

[0005] In a first aspect, the present application provides a self-cleaning negative pressure sand washing tool, comprising: a connecting outer cylinder, a connecting inner cylinder, a flow channel switching mechanism, a jet pump mechanism and a jet deblocking mechanism.

[0006] The annular part between the connecting outer cylinder and the connecting inner cylinder forms a fluid pumping channel;

[0007] The hollow part of the connecting inner cylinder forms a flow-back channel;

[0008] The flow channel switching mechanism comprises a switching shaft seat, an elastic member and a switching sliding sleeve;

[0009] The switching shaft seat is coaxially arranged with the connecting inner cylinder and connected to the lower end of the connecting inner cylinder;

[0010] The outer side wall of the switching shaft seat is provided with a switching sliding groove in the circumferential direction;

[0011] The switching sliding sleeve is in communication with the fluid pumping channel, and the switching sliding sleeve can slide along the switching sliding groove;

[0012] The elastic member is arranged between the switching sleeve and the switching shaft base;

[0013] The jet pump mechanism comprises a bypass base, a sand inlet arranged on the bypass base, and a negative pressure sand suction tool;

[0014] The negative pressure sand suction tool is in communication with the sand inlet and the flowback channel respectively;

[0015] The upper and lower ends of the bypass base are connected with the connecting outer cylinder and the jet flow unblocking mechanism respectively;

[0016] Blind hole channels and through hole channels are uniformly arranged in the bypass base in the circumferential direction; the blind hole channels are arranged corresponding to the sand inlet, and the through hole channels are in communication with the jet flow unblocking mechanism;

[0017] The switching sleeve can compress the elastic member under the action of the fluid in the fluid pump inlet channel, simultaneously perform vertical downward movement and circumferential rotation movement in a preset direction along the switching slot, and abut against the bypass base, so that the fluid pump inlet channel is in communication with the blind hole channel or the through hole channel.

[0018] Optionally, the switching slot comprises a plurality of first curve slots, second curve slots, first linear slots and second linear slots arranged at intervals in the circumferential direction of the switching shaft base, wherein a first curve slot, a second linear slot and a second curve slot are arranged between any first linear slot and adjacent first linear slot;

[0019] The upper end of each first linear slot does not penetrate the switching shaft base;

[0020] The lower end of each second linear slot does not penetrate the switching shaft base and is lower than the upper end of each first linear slot;

[0021] The lower end of any second linear slot is in communication with the lower end of adjacent first linear slot through the first curve slot, and the upper end of the second linear slot is in communication with the lower end of another adjacent first linear slot through the second curve slot.

[0022] Optionally, the flow channel switching mechanism further comprises a sliding pin;

[0023] The sliding pin is connected with the upper part of the switching sleeve, and the free end of the sliding pin is arranged in the switching slot;

[0024] The sliding pin can slide from the upper end of one first linear slot to the first curve slot, and then to the lower end of the second linear slot under the action of the fluid in the fluid pump inlet channel, so as to drive the switching sleeve to simultaneously perform vertical downward movement and circumferential rotation movement in a preset direction along the switching slot.

[0025] Or, the sliding pin can be sequentially slid from the lower end of the second linear slot to the upper end of another first linear slot under the action of the elastic member, to drive the switching sliding sleeve to simultaneously perform vertical upward linear motion and circumferential rotation motion in a preset direction along the switching sliding slot.

[0026] Optionally, the lower part of the switching sliding sleeve is provided with a bypass hole, and the bypass hole is in communication with the fluid pumping channel;

[0027] The flow channel switching mechanism further comprises a throttling hole;

[0028] The throttling hole is connected in the bypass hole.

[0029] Optionally, the bypass base is provided with a central hole;

[0030] The jet pump mechanism further comprises a throat, one end of the throat is connected to the switching shaft base, and the other end of the throat is connected to the central hole;

[0031] The switching shaft base, the throat and the central hole are all in communication with the flowback channel;

[0032] The negative pressure sand sucking tool is arranged in the central hole and below the throat;

[0033] A flow channel is arranged between the negative pressure sand sucking tool and the sand inlet.

[0034] Optionally, the negative pressure sand sucking tool comprises a power nozzle and a power nozzle base;

[0035] The power nozzle is arranged in the central hole and connected to the upper end of the power nozzle, and the power nozzle is spaced apart from the throat by a preset interval;

[0036] A flow channel is arranged between the power nozzle and the sand inlet.

[0037] The lower end of the power nozzle base is connected to the central hole;

[0038] The power nozzle base is provided with a hollow part, and the two ends of the hollow part are respectively in communication with the through hole channel and the power nozzle, so as to introduce part of the fluid in the through hole channel into the power nozzle.

[0039] Optionally, the negative pressure sand sucking tool further comprises a locking cap;

[0040] The locking cap is connected to the lower end of the power nozzle base, and is used for locking the power nozzle base, so that the interval between the power nozzle and the throat is the preset interval.

[0041] Optionally, the jet pump mechanism further comprises a filter screen.

[0042] The filter screen is connected with the bypass base and covers the sand inlet.

[0043] Optionally, the blind hole passage is provided with a cleaning nozzle.

[0044] The cleaning nozzle and the central axis of the blind hole passage form a first angle, so that the outlet direction of the cleaning nozzle is towards the filter screen.

[0045] The cleaning nozzle is used to guide the fluid in the blind hole passage to the filter screen to clean the filter screen.

[0046] Optionally, the jet unblocking mechanism comprises a jet cylinder, a forward nozzle, a plurality of first lateral nozzles and a plurality of second lateral nozzles.

[0047] The jet cylinder is connected with the bypass base.

[0048] The jet cylinder is provided with an inner cavity in communication with the through-hole passage.

[0049] The outer side wall of the jet cylinder is provided with a plurality of first accommodating cavities and second accommodating cavities in communication with the inner cavity, which accommodate the first lateral nozzles and the second lateral nozzles respectively.

[0050] The first accommodating cavities and the second accommodating cavities have a second angle and a third angle with the central axis of the jet cylinder respectively.

[0051] The forward nozzle is connected to the lower end of the jet cylinder, coaxially arranged with the jet cylinder and in communication with the inner cavity.

[0052] In a second aspect, the embodiments of the present application further provide a use method of the self-cleaning negative pressure sand washing tool, comprising:

[0053] Pumping, pumping fluid into the fluid pumping passage, under the action of the fluid, the switching sleeve compresses the elastic member, simultaneously performing vertical downward movement and circumferential rotation movement in a preset direction along the switching sliding groove, until abutting against the bypass base, so that the fluid pumping passage is in communication with the through-hole passage, and the fluid enters the jet unblocking mechanism to perform wellbore sand washing operation;

[0054] Pumping off, under the action of the elastic member, the switching sleeve simultaneously performs vertical upward movement and circumferential rotation movement in a preset direction along the switching sliding groove, until abutting against the connecting inner cylinder.

[0055] Pump, pump into the fluid channel, under the action of fluid, the switching sleeve compresses the elastic element, and simultaneously performs vertical downward movement and circumferential rotation movement in a preset direction along the switching sliding groove until abutting with the bypass base, so that the fluid pumping channel is communicated with the blind hole channel, and fluid acts on the sand inlet to perform self-cleaning operation;

[0056] The pump closing and opening operations are repeatedly performed to realize switching of the wellbore sand washing operation and the self-cleaning operation.

[0057] The beneficial effects of the above technical solutions provided in the embodiments of the present application at least include:

[0058] The present application provides a self-cleaning negative pressure sand washing tool, by setting a switching shaft base and a switching sleeve, and ingeniously setting a switching sliding groove on the switching shaft base, the switching sleeve simultaneously performs vertical upward or downward displacement along the switching sliding groove, and realizes the function of circumferential rotation movement in a preset direction, so as to achieve the purpose of switching the fluid pumping channel and the through hole channel to be communicated with the blind hole channel, and the fluid enters the blind hole channel from the fluid pumping channel to clean the sand inlet, the negative pressure sand washing tool enters the self-cleaning mode to realize the self-cleaning function. When it is necessary to start the wellbore sand washing operation again, the switching sleeve can also realize the purpose of switching the fluid pumping channel and the blind hole channel to be communicated with the through hole channel, and the fluid enters the through hole channel from the fluid pumping channel in turn until the jetting deblocking mechanism, and the wellbore is washed by the jetting deblocking mechanism. At this time, the negative pressure sand washing tool is switched to the negative pressure sand washing mode.

[0059] The above switching process can be remotely operated by the staff to achieve the purposes of downhole self-cleaning and wellbore sand washing, and is convenient and fast. The whole process does not need to lift the negative pressure sand washing tool from the wellbore, effectively reduces the operation time, improves the operation efficiency, and the switching process does not need to rely on any power equipment, which can effectively save energy.

[0060] In the self-cleaning mode, the fluid passing through the blind hole channel washes the sand inlet to clean the oil sludge, oil wax, gelatinous substances and other substances adsorbed at the sand inlet, which can effectively solve the problem of sand inlet blockage of the conventional negative pressure sand washing tool, avoid the situation of increasing the negative pressure suction resistance of the negative pressure sand washing tool, and thus ensure the efficient operation of the negative pressure sand washing tool and comprehensively improve the operation efficiency.

[0061] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structure particularly pointed out in the written description and the accompanying drawings.

[0062] The technical solutions of the present application will be further described in detail below by means of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0063] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and are meant to explain the present application and are not intended to limit the application. In the drawings:

[0064] Figure 1 is a schematic view of the structure of the negative pressure sand washing tool provided in the embodiments of the present application;

[0065] Figure 2 is a perspective view of the bypass base provided in the embodiments of the present application;

[0066] Figure 3 is a transverse cross-sectional view of the bypass base provided in the embodiments of the present application;

[0067] Figure 4 is an A-A direction cross-sectional view of Figure 3 ;

[0068] Figure 5 is a B-B direction cross-sectional view of Figure 3 ;

[0069] Figure 6 is a perspective view of the switching shaft base provided in the embodiments of the present application;

[0070] Figure 7 is a schematic view of the positional relationship of the bypass hole, through hole channel and blind hole channel provided in the embodiments of the present application;

[0071] BRIEF DESCRIPTION OF DRAWINGS

[0072] 1, connecting outer cylinder; 101, fluid pumping channel; 2, connecting inner cylinder; 201, flowback channel; 3, switching shaft base; 301, switching sliding groove; 3011, first linear groove; 3012, first curved groove; 3013, second linear groove; 3014, second curved groove; 4, sliding pin; 5, switching sliding sleeve; 501, bypass hole; 6, throttling hole; 7, throat; 8, bypass base; 801, through hole channel; 802, blind hole channel; 803, cleaning jet hole; 804, central hole; 805, sand inlet; 9, power nozzle; 10, filter screen; 11, power nozzle base; 12, locking cap; 13, jet cylinder; 14, first lateral nozzle; 15, second lateral nozzle; 16, forward nozzle; 17, elastic member. DETAILED DESCRIPTION

[0073] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it is to be understood that the present disclosure can be embodied in various forms without being limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0074] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "far", "near", "front", "back", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0075] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0076] The inventors found that in the actual working condition of the current domestic negative pressure sand washing tool, oil sludge, oil wax, and gel-like substances are often adsorbed at the sand inlet, increasing the negative pressure suction resistance of the tool, and even blocking the sand inlet, leading to tool failure and causing sand plugging and sand burying accidents.

[0077] In order to solve the above problems, the inventors have developed a self-cleaning negative pressure sand washing tool, which can realize self-cleaning of the negative pressure sand washing tool, timely remove oil sludge, oil wax, and gel-like substances adsorbed at the sand inlet, and avoid the situation of sand inlet blockage.

[0078] Embodiment one

[0079] Reference Figure 1The embodiment of the present application provides a self-cleaning negative pressure sand washing tool, which comprises a connecting outer cylinder 1 and a connecting inner cylinder 2, the connecting inner cylinder 2 is a hollow cylinder, a hollow part of the connecting inner cylinder 2 forms a flow back channel 201, and an annular part between the connecting outer cylinder 1 and the connecting inner cylinder 2 forms a fluid pumping channel 101. The upper ends of the connecting inner cylinder 2 and the connecting outer cylinder 1 can be connected with a pipe string (such as a coiled tubing) in the prior art, the negative pressure sand washing tool is connected with the pipe string, and the negative pressure sand washing tool and the pipe string are lowered into a wellbore together to perform wellbore sand washing work.

[0080] Referring to Figure 1 According to the functional structure division, the negative pressure sand washing tool further comprises three parts: a flow channel switching mechanism (not marked in the figure), a jet pump mechanism (not marked in the figure) and a jet deblocking mechanism (not marked in the figure). The flow channel switching mechanism comprises a switching shaft seat 3, an elastic member 17 and a switching sliding sleeve 5. The switching shaft seat 3 is coaxially arranged on the connecting inner cylinder 2 and connected to the lower end of the connecting inner cylinder 2, and the outer side wall of the switching shaft seat 3 is provided with a switching sliding groove 301 in the circumferential direction. The switching sliding sleeve 5 is in communication with the fluid pumping channel 101, and the switching sliding sleeve 5 can slide along the switching sliding groove 301. The elastic member 17 is arranged between the switching sliding sleeve 5 and the switching shaft seat 3.

[0081] Referring to Figures 1-5 The jet pump mechanism comprises a bypass base 8, a sand inlet 805 arranged on the bypass base 8 and a negative pressure sand suction tool (not shown in the figure). The upper and lower ends of the bypass base 8 are connected with the connecting outer cylinder 1 and the jet deblocking mechanism respectively, and the inside of the bypass base 8 is uniformly provided with a blind hole channel 802 and a through hole channel 801 in the circumferential direction, the blind hole channel 802 is arranged corresponding to the sand inlet 805, and the through hole channel 801 is in communication with the jet deblocking mechanism. The negative pressure sand suction tool is in communication with the sand inlet 805 and the flow back channel 201 respectively.

[0082] In use, the negative pressure sand washing tool is connected with the pipe string, and is lowered into the wellbore together with the pipe string. When it is necessary to wash and clean the wellbore, the staff pumps fluid into the fluid pumping channel 101 from the ground, under the action of the fluid, the switching sliding sleeve 5 compresses the elastic member 17, and simultaneously performs vertical downward movement and circumferential rotation movement in a preset direction along the switching sliding groove 301, until the switching sliding sleeve 5 abuts against the bypass base 8, so that the fluid pumping channel 101 is in communication with the through hole channel 801, the fluid sequentially passes through the fluid pumping channel 101, the through hole channel 801 and the jet deblocking mechanism, and the fluid jet is formed in the wellbore through the jet deblocking mechanism, so that the wellbore is washed and cleaned. Under the action of the negative pressure sand suction tool, the sand-carrying fluid (such as a well bottom sand bed or other blockages) formed after the wellbore is cleaned enters the inside of the negative pressure sand washing tool through the sand inlet 805, and is discharged to the ground through the flow back channel 201, at this time, the negative pressure sand washing tool is in a negative pressure sand washing mode.

[0083] Stop pumping fluid, under the action of the elastic member 17, push the switching sleeve 5 along the switching slot 301 to simultaneously perform vertical upward movement and circumferential rotation movement in a preset direction until the top end of the switching sleeve 5 abuts against the connecting inner cylinder 2, pump again, pump fluid into the fluid pumping channel 101, under the action of the fluid, the switching sleeve 5 compresses the elastic member 17, and simultaneously performs vertical downward movement and circumferential rotation movement in a preset direction along the switching slot 301 until it abuts against the bypass base 8, so that the fluid pumping channel 101 is in communication with the blind hole channel 802, and the fluid acts on the sand inlet 805 in sequence through the fluid pumping channel 101 and the blind hole channel 802, to flush the sand inlet 805 and clean the oil sludge, oil wax, and gel-like substances adsorbed at the sand inlet 805, achieving the effect of self-cleaning. At this time, the negative pressure sand washing tool of the embodiment is in the self-cleaning mode.

[0084] In the embodiment, the flow channel switching mechanism is used to realize the function of switching the fluid channel, that is, to switch the communication between the fluid pumping channel 101 and the through hole channel 801 to the communication between the fluid pumping channel 101 and the blind hole channel 802, achieving the purpose of switching from the negative pressure sand washing mode to the self-cleaning mode. When it is needed to switch to the negative pressure sand washing mode again, the fluid pumping channel 101 and the blind hole channel 802 are switched to communicate with each other by using the flow channel switching mechanism, achieving the purpose of switching from the self-cleaning mode to the negative pressure sand washing mode. The working staff can remotely switch the working mode, which is convenient to operate.

[0085] In the embodiment, the working staff can remotely switch the negative pressure sand washing tool of the embodiment to the self-cleaning mode, achieving the purpose of self-cleaning in the well, and the whole process does not need to lift the negative pressure sand washing tool from the wellbore, effectively reducing the operation time and improving the operation efficiency. At the same time, the sand inlet 805 is flushed by the fluid in the blind hole channel 802 to clean the oil sludge, oil wax, and gel-like substances adsorbed at the sand inlet 805, which can effectively solve the problem of sand inlet 805 blockage and avoid the situation of increasing the negative pressure of the negative pressure sand washing tool, thereby ensuring the efficient operation of the negative pressure sand washing tool and improving the operation efficiency.

[0086] In one specific embodiment, refer to Figure 1 , Figure 2 and Figure 5 , one end of the blind hole channel 802 penetrates the bypass base 8, the other end does not penetrate the bypass base 8, and the other end of the blind hole channel 802 is arranged towards the sand inlet 805, when the fluid pumping channel 101 and the blind hole channel 802 are in communication, the fluid can be guided to the sand inlet 805, achieving the effect of cleaning the sand inlet 805. Refer to Figure 4, both ends of the through-hole passage 801 pass through the bypass base 8. The number of the blind-hole passage 802 and the through-hole passage 801 should be consistent, and they are uniformly arranged along the circumference of the bypass base 8. Here, the specific number of the blind-hole passage 802 and the through-hole passage 801 is not limited. The number of the blind-hole passage 802 and the through-hole passage 801 can be determined according to the site working condition to meet the fluid flow demand of the site.

[0087] In a specific embodiment, the number of the blind-hole passage 802 and the through-hole passage 801 is one, and the blind-hole passage 802 and the through-hole passage 801 are symmetrically arranged.

[0088] In another embodiment, a plurality of blind-hole passages 802 and a plurality of through-hole passages 801 are arranged, and the blind-hole passages 802 and the through-hole passages 801 should be arranged alternately, that is, a through-hole passage 801 is arranged between any blind-hole passage 802 and the adjacent blind-hole passage 802. Referring to Figure 3 , an embodiment of arranging two blind-hole passages 802 and two through-hole passages 801 is given, and the two blind-hole passages 802 are symmetrically distributed, and the two through-hole passages 801 are also symmetrically distributed.

[0089] In a specific embodiment, referring to Figure 1 , the lower part of the switching sleeve 5 is provided with a bypass hole 501, and the bypass hole 501 is in communication with the fluid pumping passage 101. The number of the bypass hole 501 should be consistent with the number of the blind-hole passage 802 or the through-hole passage 801, and when the number of the bypass hole 501 is multiple, it should be uniformly distributed, so that when the switching sleeve 5 moves to abut against the bypass base 8, the bypass hole 501 can be on the same axis with the blind-hole passage 802 or the through-hole passage 801, and the fluid pumping passage 101 and the blind-hole passage 802 or the through-hole passage 801 are in communication.

[0090] Referring to Figure 1The flow channel switching mechanism further comprises throttling holes 6 connected to the bypass holes 501. The cross-sectional area of the upper end of the throttling holes 6 is larger than that of the lower end, so the flow area decreases from top to bottom. When the fluid passes through the throttling holes 6, the flow rate of the fluid increases due to the sudden decrease in flow area. According to Bernoulli's equation (a basic principle in fluid mechanics), the increase in flow rate leads to a decrease in pressure energy of the fluid, that is, the fluid pressure decreases, thus forming a pressure difference on the upper and lower sides of the throttling holes 6 to push the switching sleeve 5 to move vertically downward and rotate circumferentially in a preset direction until the switching sleeve 5 abuts against the bypass base 8, the bypass holes 501 are connected to the blind hole passages 802 or the through hole passages 801, thereby achieving the purpose of connecting the fluid pumping passages 101 to the blind hole passages 802 or the through hole passages 801. By skillfully designing the throttling holes 6 in the bypass holes 501 to form a pressure difference, the switching sleeve 5 is pushed to move, without the need for any power equipment, thereby effectively saving energy.

[0091] In one embodiment, referring to Figure 6 The switching chute 301 comprises a plurality of first linear grooves 3011, first curved grooves 3012, second linear grooves 3013 and second curved grooves 3014 arranged along the circumference of the switching shaft base 3. Any first linear groove 3011 is provided with a first curved groove 3012, a second linear groove 3013 and a second curved groove 3014 between adjacent first linear grooves 3011. The upper end of each first linear groove 3011 does not penetrate the switching shaft base 3. The lower end of each second linear groove 3013 does not penetrate the switching shaft base 3 and is lower than the upper end of each first linear groove 3011. The lower end of any second linear groove 3013 is connected to the lower end of an adjacent first linear groove 3011 through a first curved groove 3012, and the upper end of the second linear groove 3013 is connected to the lower end of another adjacent first linear groove 3011 through a second curved groove 3014.

[0092] In one embodiment, referring to Figure 1 The flow channel switching mechanism further comprises a sliding pin 4. The upper part of the switching sleeve 5 is provided with a threaded hole, and one end of the sliding pin 4 is provided with a threaded column matched with the threaded hole, so as to connect the sliding pin 4 with the upper part of the switching sleeve 5, and the free end of the sliding pin 4 is arranged in the switching chute 301.

[0093] Referring to Figure 6 and Figure 7Taking the setting of two blind hole channels 802 and two through hole channels 801 as an example, when sand flushing is required in the wellbore, the operator pumps fluid into the fluid pump channel 101 from the ground. Under the action of the fluid, the sliding pin 4 slides sequentially from the upper end of one of the first linear grooves 3011 to the first curved groove 3012, and finally to the lower end of the second linear groove 3013. That is, the movement trajectory of the sliding pin 4 along the switching groove 301 is as follows: Figure 6 The dotted line portion shown indicates that the switching sleeve 5 moves vertically downwards and rotates circumferentially in a preset direction (counterclockwise rotation in this embodiment) along the switching groove 301 simultaneously until the switching sleeve 5 abuts against the bypass base 8. During this process, the bypass hole 501 of the switching sleeve 5... Figure 7 Move to the position shown in (a) Figure 7 (b) shows that the bypass hole 501 is aligned with the central axis of the through hole channel 801 and the bypass hole 501 is connected to the through hole channel 801 so that the fluid pump inlet channel 101 is connected to the through hole channel 801, so that the negative pressure sand flushing tool of this embodiment is in negative pressure sand flushing mode.

[0094] See Figure 6 and Figure 7 When switching from negative pressure sand flushing mode to self-cleaning mode, first stop pumping fluid. Under the action of elastic element 17, sliding pin 4 slides sequentially from the lower end of the second linear groove 3013 to the second curved groove 3014, until it reaches the upper end of the other first linear groove 3011. That is, the sliding pin 4 moves along the trajectory of the switching groove 301. Figure 6 The solid line portion shown drives the switching sleeve 5 to simultaneously perform a vertical upward linear movement and a circumferential rotation in a preset direction (counterclockwise rotation in this embodiment) along the switching groove 301 until the switching sleeve 5 abuts against the connecting inner cylinder 2. During this process, the bypass hole 501 of the switching sleeve 5... Figure 7 Move to the position shown in (b) Figure 7 (c) shows the position. The pump is restarted, and under the action of the fluid, the sliding pin 4 slides from the upper end of the other first linear groove 3011 to the lower end of the second linear groove 3013 located counterclockwise from the first linear groove 3011. This drives the switching sleeve 5 to simultaneously move vertically downwards and rotate circumferentially in a preset direction (counterclockwise rotation in this embodiment) along the switching groove 301 until the switching sleeve 5 abuts against the bypass base 8. During this process, the bypass hole 501 of the switching sleeve 5... Figure 7 Move to the position shown in (c) Figure 7 At the position shown in (d), the bypass hole 501 is aligned with the central axis of the blind hole channel 802, and the bypass hole 501 is connected to the blind hole channel 802, so that the fluid pump inlet channel 101 is connected to the blind hole channel 802, and the negative pressure sand flushing tool of this embodiment is in self-cleaning mode.

[0095] By skillfully arranging the switching sliding groove 301 on the switching shaft seat 3, the rotation function of the switching sliding sleeve 5 is realized, so as to achieve the purpose of switching the fluid channel, and the free switching of the negative pressure sand washing mode and the self-cleaning mode is conveniently and quickly realized. The switching process does not need to rely on any power equipment, energy can be effectively saved, the switching process can be realized underground, the above-mentioned switching process does not need to be completed by taking out the wellbore, the operation time in the wellbore can be effectively saved, and the working efficiency is improved.

[0096] In one specific embodiment, referring to Figure 1 and Figure 2 , the bypass base 8 is provided with a central channel 804. The jet pump mechanism further comprises a throat pipe 7, one end of the throat pipe 7 is connected to the switching shaft seat 3, and the other end of the throat pipe 7 is connected to the central channel 804. Specifically, the upper part of the throat pipe 7 is provided with a stepped surface, which is inserted into the upper end of the central channel of the bypass base 8, the switching shaft seat 3 is screwed into the throat pipe 7 and locked, preventing the throat pipe 7 from moving up and down. The switching shaft seat 3, the throat pipe 7 and the central channel 804 are all in communication with the flowback channel 201. The negative pressure sand suction tool is arranged in the central channel 804 and below the throat pipe 7, and a flow channel (not marked in the figure) is arranged between the negative pressure sand suction tool and the sand inlet 805. Here, the negative pressure sand suction tool can adopt a device capable of generating a negative pressure state in the prior art. Under the action of the negative pressure, the negative pressure sand suction tool can suck the sand-carrying fluid in the wellbore into the sand inlet 805, and then to the vicinity of the negative pressure sand suction tool through the flow channel, and then into the throat pipe 7, and then transported to the ground through the flowback channel 201.

[0097] In one specific embodiment, referring to Figure 1 , the negative pressure sand suction tool comprises a power nozzle 9 and a power nozzle seat 11. The power nozzle 9 is arranged in the central channel 804, and the power nozzle 9 is spaced apart from the throat pipe 7 by a predetermined distance. The predetermined distance is determined according to the optimal negative pressure sand washing suction efficiency of the power nozzle 9. A flow channel is arranged between the power nozzle 9 and the sand inlet 805. The upper end of the power nozzle seat 11 is connected to the power nozzle 9, and the lower end of the power nozzle seat 11 is connected to the central channel 804. First and second external threads can be arranged on the outer side wall of the upper end and the lower end of the power nozzle seat 11 respectively. Correspondingly, the outer side wall of the power nozzle 9 and the central channel 804 are respectively provided with first and second internal threads. The first external thread matches the first internal thread, and the second external thread matches the second internal thread, so as to realize the threaded connection of the upper and lower ends of the power nozzle seat 11 with the power nozzle 9 and the central channel 804 respectively, and make the connection more reliable. The power nozzle seat 11 is provided with a hollow portion, and the two ends of the hollow portion are respectively in communication with the through hole channel 801 and the power nozzle 9, so as to introduce part of the fluid in the through hole channel 801 into the power nozzle 9.

[0098] When the negative pressure sand washing tool of the embodiment is in the negative pressure sand washing mode, the fluid pump-in channel 101 is in communication with the through-hole channel 801, a part of the fluid can flow to the jetting unblocking mechanism, and the wellbore sand removal work is performed by the jetting unblocking mechanism, another part of the fluid enters the hollow part of the power nozzle seat 11, and is introduced into the power nozzle 9. The high-speed jet flow is generated through the power nozzle 9, and the negative pressure is formed in the area between the power nozzle 9 and the throat pipe 7. The sand-carrying fluid is sequentially pumped through the sand inlet 805, the flow channel, and the bypass base 8, mixed with the high-speed jet flow generated by the power nozzle 9, and the fluid kinetic energy is converted into potential energy after entering the throat pipe 7. The sand-carrying fluid is lifted to the ground through the flowback channel 201. By arranging the power nozzle 9, the flowback work of the sand-carrying fluid can be completed without any power equipment, and the operation cost is saved.

[0099] In one specific embodiment, referring to Figure 1 , the negative pressure sand pumping tool further comprises a locking cap 12 connected to the lower end of the power nozzle seat 11. Since the power nozzle seat 11 is threadedly connected with the central hole 804, according to different unblocking working conditions, the staff can adjust the distance between the power nozzle 9 and the throat pipe 7 by rotating the lower end of the power nozzle seat 11 until the preset distance, and lock the power nozzle seat 11 through the locking cap 12, so that the distance between the power nozzle 9 and the throat pipe 7 is the preset distance, the negative pressure sand pumping efficiency is optimized, and the adaptability of the negative pressure sand pumping tool of the embodiment to different well conditions is improved.

[0100] In one specific embodiment, referring to Figure 1 and Figure 2 , the outer wall of the bypass base 8 is provided with a special-shaped through hole as the sand inlet 805. The jet pump mechanism further comprises a filter screen 10 connected with the bypass base 8 and covering the sand inlet 805. By arranging the filter screen 10, the large particles of gravel or rock debris in the sand-carrying fluid can be filtered, so that the large particles of gravel or rock debris are prevented from entering the negative pressure sand pumping tool to cause blockage and affect the normal use of the negative pressure sand pumping tool.

[0101] In one specific embodiment, referring to Figure 5The blind hole channel 802 is provided with a cleaning jet hole 803, and an included angle between the cleaning jet hole 803 and a central axis of the blind hole channel 802 is a first included angle, so that an outlet direction of the cleaning jet hole 803 is towards the filter screen 10. The cleaning jet hole 803 is used to guide fluid in the blind hole channel 802 to the filter screen 10, so as to clean the filter screen 10. In the embodiment, the inventor comprehensively considers factors such as a distance between the cleaning jet hole 803 and the filter screen 10, an impact area of the cleaning jet hole 803 on the filter screen 10, a size of the cleaning jet hole 803 and a size of the filter screen 10, and sets the first included angle to be 20°-45°. In the range, the best flushing area and flushing intensity of the cleaning jet hole 803 on the filter screen 10 can be ensured, so that the best cleaning effect on the filter screen 10 can be achieved.

[0102] In one specific embodiment, referring to Figure 1 The jetting mechanism includes a jetting barrel 13, a forward nozzle 16, a plurality of first lateral nozzles 14 and a plurality of second lateral nozzles 15, which are used for jetting and sand stirring. The jetting barrel 13 is connected with the bypass base 8. Specifically, a third external thread can be arranged on an outer sidewall of the bypass base 8, and an inner sidewall of the jetting barrel 13 is provided with a third internal thread matched with the third external thread, so that the jetting barrel 13 and the bypass base 8 are connected in a threaded connection manner, and the connection is more reliable. When the jetting barrel 13 is sleeved on the bypass base 8, the jetting barrel 13 can also achieve the clamping effect on the filter screen 10. A clamping groove can be arranged at a lower end of the filter screen 10, and the jetting barrel 13 is provided with a clamping column which can be clamped in the clamping groove, so that the jetting barrel 13 can limit the filter screen 10.

[0103] The jetting barrel 13 is provided with an inner cavity which is communicated with the through hole channel 801. The forward nozzle 16 is connected to a lower end of the jetting barrel 13 and is coaxially arranged with the jetting barrel 13 and communicated with the inner cavity of the jetting barrel 13. An outer sidewall of the jetting barrel 13 is provided with a plurality of first accommodating cavities (not marked in the figure) and second accommodating cavities (not marked in the figure) which are communicated with the inner cavity and accommodate the first lateral nozzles 14 and the second lateral nozzles 15 respectively. The first accommodating cavities and the second accommodating cavities have a second included angle and a third included angle with a central axis of the jetting barrel 13 respectively, so that the first lateral nozzles 14 are arranged obliquely upward, and the second lateral nozzles 15 are arranged obliquely downward, so as to achieve the effect of the maximum jetting range of the first lateral nozzles 14 and the second lateral nozzles 15 and achieve the best jetting and unblocking effect on the well wall. Meanwhile, the nozzle hole diameters of the first lateral nozzles 14 and the second lateral nozzles 15 can be replaced according to the specific unblocking situation in the well, so as to adjust the jetting intensity adaptively.

[0104] The inventor evenly arranges 3 first lateral nozzles 14 and 3 second lateral nozzles 15 along the circumference of the jet cylinder 13 by comprehensively considering the wellbore, the flushing area and jetting intensity of the single first lateral nozzle 14 and the flushing area and jetting intensity of the single second lateral nozzle 15, so as to ensure the circumferential flushing area covering the wellbore. The 3 first lateral nozzles 14 are located at the upper part of the jet cylinder 13, and the second included angle is 30°-60°; the 3 second lateral nozzles 15 are located at the lower part of the jet cylinder 13, and the third included angle is 30°-60°, so as to achieve the maximum jetting range and the maximum vertical flushing area of the wellbore.

[0105] In the embodiment, by reasonably setting the number and aperture of the first lateral nozzles 14, the number and aperture of the second lateral nozzles 15, the second included angle and the third included angle, the jet impact area is reasonably distributed, the best sand washing effect is achieved, and the impact and plug removal capacity is maximized under the limited displacement. In combination with the forward nozzle 16, the sand washing displacement is reasonably distributed, the sand washing effect is improved, the sand removal is accelerated by sand washing, and the negative pressure sand washing effect is improved.

[0106] Referring to Figure 1 The embodiment is mainly used for sand washing and plug removal operation of low-pressure oil and gas wells, jet impact plug removal is realized by the first lateral nozzles 14 and the second lateral nozzles 15, the sand-carrying fluid generated is sucked and lifted to the ground under the action of the power nozzle 9. By setting the flow channel switching mechanism, the negative pressure sand washing mode can be remotely switched to the self-cleaning mode, the negative pressure sand washing tool is self-cleaned underground, the negative pressure sand washing tool is prevented from being blocked and failed, and the negative pressure sand washing operation efficiency is improved.

[0107] The negative pressure sand washing tool includes two working modes: a negative pressure sand washing mode and a self-cleaning mode, and the working processes of the two working modes are described in detail below.

[0108] The negative pressure sand washing mode: the ground pump fluid, the fluid is delivered to the fluid pumping channel 101, a pressure difference is generated through the throttle hole 6, the switching sleeve 5 is pushed to move downward along the switching sliding groove 301 (that is, vertical downward movement and circumferential rotation movement in a preset direction are simultaneously performed), until the switching sleeve 5 abuts against the bypass base 8, the bypass hole 501 of the switching sleeve 5 is aligned and communicated with the through hole channel 801 of the bypass base 8, and the fluid enters the area between the bypass base 8 and the jet cylinder 13 through the through hole channel 801. Then the fluid is divided into two parts, one part of the fluid enters the inner cavity of the jet cylinder 13, and flows out from the first side nozzle 14, the second side nozzle 15 and the front nozzle 16 respectively and forms high-speed jets, the first side nozzle 14 and the second side nozzle 15 are used for impacting the sand bed in the wellbore and the well wall, and the front nozzle 16 is used for stirring the sand bed and accelerating the sand-carrying fluid to move to the vicinity of the filter screen 10. The other part of the fluid enters the power nozzle seat 11 and is introduced into the power nozzle 9 by the power nozzle seat 11, high-speed jets are generated through the power nozzle 9 and local negative pressure is formed in the vicinity, the sand-carrying fluid outside the negative pressure sand washing tool is sucked into the bypass base 8 through the filter screen 10, the sand-carrying fluid is mixed with the high-speed jets generated by the power nozzle 9, the fluid kinetic energy is converted into potential energy after entering the throat 7, and the fluid is lifted to the ground through the flowback channel 201.

[0109] The self-cleaning mode: after the tool works in the negative pressure sand washing mode for a period of time, the blockages such as oil sludge, oil wax and gelatinous substances in the wellbore are adsorbed on the filter screen 10, and the ability of the power nozzle 9 to suck fluid is reduced. The ground pump is stopped, the elastic member 17 pushes the switching sleeve 5 to move upward along the switching sliding groove 301 (that is, vertical upward movement and circumferential rotation movement in a preset direction are simultaneously performed), and then the pump is started again, the switching sleeve 5 moves downward along the switching sliding groove 301 (that is, vertical downward movement and circumferential rotation movement in a preset direction are simultaneously performed), the bypass hole 501 of the switching sleeve 5 is aligned and communicated with the blind hole channel 802, and after the fluid enters the blind hole channel 802, high-speed jets are formed through the cleaning jet holes 803, the blockages on the filter screen 10 are impacted and broken from the inside, are discharged from the filter screen 10, play a role in dredging and unblocking, and achieve the effect of self-cleaning.

[0110] Embodiment two

[0111] Based on the same inventive concept, the embodiment of the present application further provides a use method of the self-cleaning negative pressure sand washing tool, which comprises the following steps:

[0112] Step S1, the pump is started, fluid is pumped into the fluid pumping channel, under the action of the fluid, the switching sleeve compresses the elastic member, vertical downward movement and circumferential rotation movement in a preset direction are simultaneously performed along the switching sliding groove, until the switching sleeve abuts against the bypass base, so that the fluid pumping channel is communicated with the through hole channel, and the fluid enters the jet unblocking mechanism to perform wellbore sand washing operation;

[0113] Step S2, the pump is closed, under the action of the elastic member, the switching sleeve simultaneously performs vertical upward movement and circumferential rotation movement in a preset direction along the switching sliding groove until abutting against the connecting inner cylinder;

[0114] Step S3, the pump is opened, fluid is pumped into the fluid pumping channel, under the action of the fluid, the switching sleeve compresses the elastic member, simultaneously performs vertical downward movement and circumferential rotation movement in a preset direction along the switching sliding groove until abutting against the bypass base, so that the fluid pumping channel is communicated with the blind hole channel, and the fluid acts on the sand inlet to perform self-cleaning operation;

[0115] Step S4, the pump closing and opening operations are repeatedly performed to realize switching wellbore sand washing operation and self-cleaning operation.

[0116] The use method of the self-cleaning negative pressure sand washing tool provided by the embodiment of the application has similar implementation principles and technical effects to those of the first embodiment, and thus will not be described here.

[0117] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. The present disclosure is not limited to the precise structures described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. A self-cleaning negative pressure sandblasting tool, characterized in that, include: Connecting outer cylinder, connecting inner cylinder, flow channel switching mechanism, jet pump mechanism, and jet unblocking mechanism; The annular portion between the connecting outer cylinder and the connecting inner cylinder forms a fluid pumping channel; The hollow portion of the connecting inner cylinder forms a return channel; The flow channel switching mechanism includes a switching shaft seat, an elastic element, and a switching sleeve; The switching shaft seat is coaxially arranged with the connecting inner cylinder and connected to the lower end of the connecting inner cylinder; The outer wall of the switching shaft seat is provided with a switching groove along the circumferential direction; The switching sleeve is connected to the fluid pump inlet channel, and the switching sleeve can slide along the switching groove; The elastic element is disposed between the switching sleeve and the switching shaft seat; The jet pump mechanism includes: a bypass base, a sand inlet disposed on the bypass base, and a negative pressure sand suction tool; The negative pressure sand suction tool is connected to the sand inlet and the return channel respectively; The upper and lower ends of the bypass base are respectively connected to the connecting outer cylinder and the jet unblocking mechanism; The bypass base is provided with blind holes and through holes evenly distributed around its circumference; the blind holes correspond to the sand inlet, and the through holes are connected to the jet unblocking mechanism. The switching sleeve can compress the elastic element under the action of the fluid in the fluid pumping channel, and move vertically downward and rotate circumferentially in a preset direction along the switching groove until it abuts against the bypass base, so that the fluid pumping channel is connected to the blind hole channel or the through hole channel.

2. The negative pressure sandblasting tool as described in claim 1, characterized in that, The switching groove includes a plurality of first curved grooves, second curved grooves, first linear grooves and second linear grooves arranged circumferentially along the switching shaft seat, wherein each first linear groove is provided with a first curved groove, a second linear groove and a second curved groove between it and an adjacent first linear groove. The upper end of each of the first linear slots does not penetrate the switching shaft seat; The lower end of each of the second linear slots does not penetrate the switching shaft seat and is lower than the upper end of each of the first linear slots; The lower end of any second linear groove is connected to the lower end of an adjacent first linear groove through the first curved groove, and the upper end of the second linear groove is connected to the lower end of another adjacent first linear groove through the second curved groove.

3. The negative pressure sandblasting tool as described in claim 2, characterized in that, The flow channel switching mechanism also includes a sliding pin; The sliding pin is connected to the upper part of the switching sleeve, and the free end of the sliding pin is located in the switching groove. The sliding pin can slide sequentially from the upper end of one of the first linear grooves to the first curved groove, and then to the lower end of the second linear groove, under the action of the fluid in the fluid pumping channel, so as to drive the switching sleeve to move vertically downward and rotate circumferentially in a preset direction along the switching groove. Alternatively, the sliding pin can slide sequentially from the lower end of the second linear groove to the second curved groove, and then to the upper end of the other first linear groove, under the action of the elastic element, so as to drive the switching sleeve to simultaneously perform vertical upward linear movement and circumferential rotational movement in a preset direction along the switching groove.

4. The negative pressure sandblasting tool as described in claim 1, characterized in that, The lower part of the switching sleeve is provided with a bypass hole, which is connected to the fluid pump inlet channel; The flow channel switching mechanism also includes a throttling orifice; The throttling orifice is connected to the bypass orifice.

5. The negative pressure sandblasting tool as described in claim 1, characterized in that, The bypass base has a central channel; The jet pump mechanism also includes a throat tube, one end of which is connected to the switching shaft seat, and the other end of which is connected to the central channel; The switching shaft seat, the throat tube, and the central channel are all connected to the return channel; The negative pressure sand suction tool is located inside the central channel and below the throat tube; A flow channel is provided between the negative pressure sand suction tool and the sand inlet.

6. The negative pressure sandblasting tool as described in claim 5, characterized in that, The negative pressure sand suction tool includes a power nozzle and a power nozzle seat; The power nozzle is located in the central channel and connected to the upper end of the power nozzle, and the power nozzle is spaced apart from the throat by a preset distance. A flow channel is provided between the power nozzle and the sand inlet; The lower end of the power nozzle seat is connected to the central channel; The power nozzle seat has a hollow portion, and the two ends of the hollow portion are respectively connected to the through-hole channel and the power nozzle, so as to introduce part of the fluid in the through-hole channel into the power nozzle.

7. The negative pressure sandblasting tool as described in claim 6, characterized in that, The negative pressure sand suction tool also includes a locking cap; The locking cap is connected to the lower end of the power nozzle seat and is used to lock the power nozzle seat so that the distance between the power nozzle and the throat is a preset distance.

8. The negative pressure sandblasting tool as described in claim 1, characterized in that, The jet pump mechanism also includes a filter screen; The filter screen is connected to the bypass base and covers the sand inlet.

9. The negative pressure sandblasting tool as described in claim 8, characterized in that, The blind hole channel is provided with cleaning spray holes; The angle between the cleaning nozzle and the central axis of the blind channel is the first angle, so that the outlet direction of the cleaning nozzle is towards the filter screen; The cleaning nozzle is used to direct fluid from the blind channel to the filter screen to clean it.

10. The negative pressure sandblasting tool as described in claim 1, characterized in that, The jet unblocking mechanism includes a jet tube, a forward nozzle, multiple first lateral nozzles, and multiple second lateral nozzles; The jet tube is connected to the bypass base; The jet tube is provided with an inner cavity that communicates with the through-hole channel; The outer wall of the jet tube is provided with a plurality of first receiving cavities and second receiving cavities communicating with the inner cavity, which respectively accommodate the first lateral nozzle and the second lateral nozzle; The first receiving cavity and the second receiving cavity have a second included angle and a third included angle with the central axis of the jet tube, respectively; The forward nozzle is connected to the lower end of the jet tube, is coaxially arranged with the jet tube, and communicates with the inner cavity.

11. A method for using a self-cleaning negative pressure sandblasting tool, characterized in that, include: Start the pump and pump fluid into the fluid pumping channel. Under the action of the fluid, switch the sliding sleeve to compress the elastic element. Simultaneously move vertically downward and rotate circumferentially in a preset direction along the switching groove until it abuts against the bypass base, so that the fluid pumping channel is connected to the through hole channel. The fluid enters the jet unblocking mechanism to perform well shaft sand flushing operation. When the pump is turned off, under the action of the elastic element, the switching sleeve moves vertically upward and rotates circumferentially in a preset direction along the switching groove until it abuts against the connecting inner cylinder. Start the pump and pump fluid into the fluid pumping channel. Under the action of the fluid, the switching sleeve compresses the elastic element and moves vertically downward and rotates circumferentially in a preset direction along the switching groove until it abuts against the bypass base, so that the fluid pumping channel is connected to the blind hole channel and the fluid acts on the sand inlet to perform self-cleaning operation. Repeatedly perform pump shut-off and pump start-up operations to switch between wellbore sand flushing and self-cleaning operations.

Images