Electric submersible pump production tubular column

Abstract

The invention relates to the technical field of underground oil extraction equipment, in particular to an electric submersible pump production pipe column which comprises an electric submersible pump and a flow stabilizing device arranged above the electric submersible pump, the flow stabilizing device comprises a barrel, the barrel is provided with an overflowing inner cavity, a flow stabilizing baffle is arranged in the overflowing inner cavity, and the overflowing inner cavity is provided with a flow stabilizing baffle. The two side plate faces of the flow stabilizing baffle are back to back in the axial direction of the barrel, flow passing holes are formed in the flow stabilizing baffle, the center lines of the flow passing holes extend in the axial direction of the barrel, rotational flow discharged by the electric submersible pump enters an inner flow passing cavity of the barrel of the flow stabilizing device, the rotational force of fluid is weakened due to the influence of the flow stabilizing baffle, the fluid is rectified through the flow passing holes, and the flow stabilizing effect is improved. According to the flow stabilizing device, the rotational flow is inhibited, so that the fluid tends to flow upwards in the axial direction of the tubular column, a stable flowing state is formed when the fluid continues to be lifted upwards through the flow stabilizing device, abrasion caused by the fact that the rotational flow drives a movable part in the tubular column to rotate is avoided, and faults caused by the rotational flow are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of downhole oil production equipment, in particular to a submersible electric pump production pipe column. BACKGROUND

[0002] Submersible electric pump oil production is one of the important mechanical production methods in oilfield development. Its working principle is to use the high-speed rotation of the submersible motor to drive the multi-stage guide wheel inside the submersible electric pump to rotate, and then lift the well fluid upward to the ground. The single flow valve is arranged on the submersible electric pump production pipe column, and the single flow valve is located above the submersible electric pump. When the submersible electric pump stops, it can prevent the liquid in the pipe column from flowing back to damage the submersible motor and the submersible electric pump. However, during the production of the submersible electric pump, due to the rotation of the multi-stage guide wheel inside the submersible electric pump, the lifted well fluid is in a rotational flow state when it is discharged from the discharge port of the submersible electric pump. When it reaches the single flow valve above the discharge port, the rotational flow slows down, but it is still not a relatively stable laminar flow. The rotational flow will drive the valve ball of the single flow valve to rotate, causing the valve ball of the single flow valve to be eccentrically worn with the cylindrical valve seat. With the long-time operation of the submersible electric pump, the wear gradually increases, which can result in two consequences: first, the cylinder wall of the cylindrical valve seat of the single flow valve becomes thin and is eventually worn out, causing downhole accidents; second, when the well is stopped, the valve ball with a smaller diameter will fall from the inner hole of the valve seat to the shaft head of the submersible electric pump, causing pump jamming and leading to downhole accidents such as submersible motor burning.

[0003] At present, in order to avoid the above-mentioned downhole accidents, the conventional method is to extend the buffer distance to reduce the rotational force of the liquid flow. Generally, the distance from the discharge port of the submersible electric pump to the single flow valve is extended to 40-60 meters, and a buffer section is formed in the inner cavity of the long oil pipe between the submersible electric pump and the single flow valve. However, due to the excessive initial speed of the rotational flow discharged from the discharge port of the submersible electric pump, and the continuous state of the rotational flow, the rotational flow is always generated. The buffer section formed in the inner cavity of the long oil pipe cannot eliminate the rotational flow well, and when the lifted liquid reaches the single flow valve at the upper part of the pipe column, it can still drive the valve ball of the single flow valve to rotate, causing wear. When the operation period of the submersible electric pump is long enough, the cylinder wall of the cylindrical valve seat of the single flow valve can still be worn and perforated, and the pump can be jammed, causing the well to be stopped and lying. SUMMARY

[0004] The purpose of the present application is to provide a submersible electric pump production pipe column to solve the problem that the rotational flow discharged from the submersible electric pump can drive the rotating parts in the pipe column to rotate and cause wear and failure.

[0005] The technical scheme of the submersible electric pump production pipe column of the present application is: The utility model provides an electric submersible pump production string, comprising an electric submersible pump, a flow stabilizing device is arranged above the electric submersible pump, the flow stabilizing device comprises a cylinder body, the cylinder body has a through-flow inner cavity for the fluid discharged by the electric submersible pump to pass through, a flow stabilizing baffle is arranged in the through-flow inner cavity, the two side surfaces of the flow stabilizing baffle are opposite in the axial direction of the cylinder body, the flow stabilizing baffle is provided with a through-flow hole, and the center line of the through-flow hole extends along the axial direction of the cylinder body.

[0006] Further, the flow stabilizing baffles are arranged in the axial direction of the cylinder body in a spaced manner, and two adjacent flow stabilizing baffles comprise an upstream baffle located upstream in the fluid flow direction and a downstream baffle located downstream in the fluid flow direction, and a flow stabilizing cavity is formed between the two adjacent flow stabilizing baffles.

[0007] Further, the flow stabilizing baffle is provided with a first through-flow hole, and the diameter of the first through-flow hole on the downstream baffle is greater than the diameter of the first through-flow hole on the upstream baffle.

[0008] Further, the flow stabilizing baffle is provided with a second through-flow hole at the center thereof, and the first through-flow holes are circumferentially distributed at the periphery of the second through-flow hole, and the diameter of the second through-flow hole on the upstream baffle is equal to the diameter of the second through-flow hole on the downstream baffle.

[0009] Further, the sum of the cross-sectional areas of the through-flow holes on the downstream baffle is greater than the sum of the cross-sectional areas of the through-flow holes on the upstream baffle.

[0010] Further, the number of the through-flow holes on the downstream baffle is less than the number of the through-flow holes on the upstream baffle.

[0011] Further, the thickness of the upstream baffle is less than the thickness of the downstream baffle.

[0012] Further, the cross-sectional area of the flow stabilizing cavity is 3-5 times the sum of the cross-sectional areas of the through-flow holes on the upstream baffle.

[0013] Further, the diameters of the through-flow holes on the flow stabilizing baffle located most upstream in the fluid flow direction are the same.

[0014] Further, the utility model provides an electric submersible pump production string, comprising an electric submersible pump, a flow stabilizing device is arranged above the electric submersible pump, the flow stabilizing device comprises a cylinder body, the cylinder body has a through-flow inner cavity for the fluid discharged by the electric submersible pump to pass through, a flow stabilizing baffle is arranged in the through-flow inner cavity, the two side surfaces of the flow stabilizing baffle are opposite in the axial direction of the cylinder body, the flow stabilizing baffle is provided with a through-flow hole, and the center line of the through-flow hole extends along the axial direction of the cylinder body.

[0015] Beneficial effects: the present application improves the production string of the submersible electric pump in the prior art, by setting the flow stabilizing device above the production string of the submersible electric pump, the rotational flow discharged by the submersible electric pump enters the overflow inner cavity of the cylinder of the flow stabilizing device, the rotating force of the fluid is weakened by the influence of the flow stabilizing baffle in the overflow inner cavity, the fluid is rectified by passing through the overflow hole, which plays a role in inhibiting the rotational flow, and is conducive to making the fluid tend to be laminar flow along the axial direction of the string upward, so that when the fluid continues to lift upward after passing through the flow stabilizing device, a stable flow state is formed, which is conducive to avoiding the rotation of the movable part in the string driven by the rotational flow and the easy wear and tear, and further reducing the failure caused by the rotational flow. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Figure is a schematic diagram of the submersible electric pump production string of the embodiment of the present application being lowered into a well; Figure 2 Figure is a structural schematic diagram of the flow stabilizing device in Figure 1 Figure is a schematic diagram of the first baffle in Figure 3 Figure is a schematic diagram of the second baffle in Figure 2 Figure is a schematic diagram of the second baffle in Figure 4 Figure 2 Figure is a schematic diagram of the second baffle in Figure 5 Figure is a schematic diagram of the second baffle in Figure 2

[0017] In the figure: 100, technical casing; 200, oil layer; 300, upper oil pipe; 400, oil drain; 500, single flow valve; 600, flow stabilizing device; 700, submersible electric pump; 1, upper connecting end; 2, snap spring; 3, second baffle; 31, second center hole; 32, second side hole; 4, flow stabilizing cavity; 5, first baffle; 51, first center hole; 52, first side hole; 6, lower connecting end. DETAILED DESCRIPTION

[0018] The submersible electric pump production string of the present application is provided with a flow stabilizing device above the submersible electric pump, the rotational flow discharged by the submersible electric pump enters the overflow inner cavity of the cylinder of the flow stabilizing device, the rotating force of the fluid is weakened by the influence of the flow stabilizing baffle in the overflow inner cavity, the fluid is rectified by passing through the overflow hole, which plays a role in inhibiting the rotational flow, and is conducive to making the fluid tend to be laminar flow along the axial direction of the string upward, so that when the fluid continues to lift upward after passing through the flow stabilizing device, a stable flow state is formed, which is conducive to avoiding the rotation of the movable part in the string driven by the rotational flow and the easy wear and tear, and further reducing the failure caused by the rotational flow.

[0019] Embodiment of the submersible electric pump production string of the present application: As Figure 1 ​​As shown in the drawings, the electric submersible pump production string comprises an electric submersible pump 700, a flow stabilizer 600, a check valve 500, a flow release device 400 and an upper tubing 300 extending to the wellhead, the valve ball of the check valve 500 is a movable part in the string, the flow stabilizer 600 is located above the electric submersible pump 700, the check valve 500 is located above the flow stabilizer 600, the flow release device 400 is located above the check valve 500, the electric submersible pump 700 and the flow stabilizer 600, the flow stabilizer 600 and the check valve 500, and the check valve 500 and the flow release device 400 are connected by corresponding tubing respectively, the upper end of the flow release device 400 is connected with the upper tubing 300, the electric submersible pump production string is lowered into the technical casing 100 of the oil well, and the fluid of the oil layer 200 is extracted.

[0020] As shown in the drawings, Figure 1 and Figure 2 As shown in the drawings, the flow stabilizer 600 of the electric submersible pump production string comprises a cylinder body, the axial direction of the cylinder body is upward and downward, the upper end of the cylinder body is an upper connecting end 1, the upper connecting end 1 is provided with an internal thread for connecting with the external thread of the corresponding tubing, the lower end of the cylinder body is a lower connecting end 6, the lower connecting end 6 is provided with an external thread for connecting with the internal thread of the corresponding tubing, so as to connect the flow stabilizer in series on the string. The inner cavity of the cylinder body forms a flow-through inner cavity for the fluid discharged by the electric submersible pump to pass through, the flow-through inner cavity is provided with a flow stabilizing baffle, the two side surfaces of the flow stabilizing baffle are opposite in the axial direction of the cylinder body, the flow stabilizing baffle is provided with a flow-through hole, the center line of the flow-through hole extends along the axial direction of the cylinder body, and the flow stabilizing baffle and the flow-through hole thereon can make the rotational flow flowing into the flow stabilizer from below become stable upward flow and flow out.

[0021] The flow stabilizing baffle is provided with two baffles, namely a first baffle 5 and a second baffle 3, and the first baffle 5 and the second baffle 3 are arranged in the axial direction of the cylinder body. The fluid in the string flows from below to above, the first baffle 5 constitutes an upstream baffle in the upstream of the fluid flow direction, the second baffle 3 constitutes a downstream baffle in the downstream of the fluid flow direction, a flow stabilizing cavity 4 is formed between the first baffle 5 and the second baffle 3, the flow stabilizing cavity 4 is the part of the inner cavity of the cylinder body between the first baffle 5 and the second baffle 3, the fluid flows into the flow stabilizing cavity 4 after passing through each flow-through hole on the first baffle 5, and then flows out through each flow-through hole on the second baffle 3, which is beneficial to the rectification and stabilization of the flow.

[0022] As shown in the drawings, Figure 2 and Figure 5As shown, the first baffle plate 5 is integrally formed with the cylinder body, and the first baffle plate 5 is arranged at the lower part of the cylinder body. The second baffle plate 3 is detachably arranged in the cylinder body, and the second baffle plate 3 is arranged at the upper part of the cylinder body. The upper and lower side plate surfaces of the first baffle plate 5 and the second baffle plate 3 are perpendicular to the axis of the cylinder body. An upward step surface is arranged on the inner wall of the upper part of the cylinder body, the second baffle plate 3 is supported on the upward step surface, and a clamping groove for mounting the snap spring 2 is further arranged on the inner wall of the cylinder body above the upward step surface, so as to fix the second baffle plate 3 in the cylinder body through the snap spring 2. The outer peripheral surface of the second baffle plate 3 is tightly matched with the inner wall surface of the cylinder body, the second baffle plate 3 is axially limited and fixed by the snap spring 2, the processing of the cylinder body is facilitated, the second baffle plate 3 is convenient to disassemble, clean and reuse subsequently.

[0023] As shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 , the first baffle plate 5 is provided with a first center hole 51 and a plurality of first side holes 52, and the first center hole 51 and the first side hole 52 both constitute flow-through holes on the first baffle plate 5. The second baffle plate 3 is provided with a second center hole 31 and a plurality of second side holes 32, and the second center hole 31 and the second side hole 32 both constitute flow-through holes on the second baffle plate 3. Among them, the first side hole 52 constitutes the first flow-through hole on the first baffle plate 5, the second side hole 32 constitutes the first flow-through hole on the second baffle plate 3, the first center hole 51 constitutes the second flow-through hole on the first baffle plate 5, and the second center hole 31 constitutes the second flow-through hole on the second baffle plate 3. The second flow-through hole is arranged at the center of the flow stabilizing baffle plate, the first flow-through holes are circumferentially distributed at the periphery of the second flow-through hole, and the first flow-through holes are uniformly distributed in the circumferential direction, so as to fully utilize the surface area of the flow stabilizing baffle plate and facilitate the guarantee of the structural strength of the flow stabilizing baffle plate. The diameter of the second side hole 32 on the second baffle plate 3 is greater than the diameter of the first side hole 52 on the first baffle plate 5, so as to facilitate the increase of the flow area of the second baffle plate 3 and the reduction of the pressure loss of the fluid passing through the second baffle plate 3 while the second baffle plate 3 plays a role of rectification.

[0024] The diameter of the first center hole 51 on the first baffle plate 5 is equal to the diameter of the second center hole 31 on the second baffle plate 3, so as to facilitate the arrangement of the second side holes 32 with larger size on the second baffle plate 3 and avoid the diameter of the second baffle plate 3 being too large. The first center hole 51 and the second center hole 31 are coaxially arranged, which is conducive to the flow of fluid. The first baffle plate 5 constitutes the most upstream flow stabilizing baffle plate in the flow direction of the fluid, the diameters of the flow-through holes on the first baffle plate 5 are the same, that is, the diameter of the first center hole 51 is the same as the diameter of the first side hole 52, so as to change the liquid flow line and achieve the purpose of cyclone change direction, and the liquid flow is stabilized.

[0025] The sum of the cross-sectional areas of the flow holes of the second baffle 3 is greater than the sum of the cross-sectional areas of the flow holes of the first baffle 5, and the cross-section of the flow hole is perpendicular to the center line thereof. In the present embodiment, the first side holes 52 on the first baffle 5 are eight in number, and the second side holes 32 on the second baffle 3 are four in number. The diameter of the second side holes 32 is 1.5 times the diameter of the first side holes 52, so that the flow area of the second baffle 3 is relatively large, which is beneficial to the flow of liquid from the steady flow cavity 4 and reduces the pressure loss. The number of the flow holes on the second baffle 3 is less than the number of the flow holes on the first baffle 5, so as to avoid the second baffle 3 being too large in diameter and facilitate the flow of liquid through the second side holes 32 with a larger diameter and reduce the pressure loss.

[0026] The lower connecting end portion 6 cavity is communicated with the steady flow cavity 4 through the flow holes on the first baffle 5, and the steady flow cavity 4 is communicated with the upper connecting end portion 1 cavity through the flow holes on the second baffle 3. The flow inner cavity of the cylinder includes the lower connecting end portion 6 cavity, the steady flow cavity 4 and the upper connecting end portion 1 cavity. The cross-sectional area of the steady flow cavity 4 is 4 times the sum of the cross-sectional areas of the flow holes on the first baffle 5, so as to regulate the flow of liquid with high flow rate through the first baffle 5 in the steady flow cavity 4 and stabilize the flow rate.

[0027] The thickness of the first baffle 5 is less than the thickness of the second baffle 3, and the thickness direction is the up-down direction. The first baffle 5 is provided with flow holes with the same diameter. The thickness of the first baffle 5 is relatively small, which is beneficial to reduce the pressure loss of the fluid passing through the first baffle 5 and does not affect the normal production of the submersible electric pump. The thickness of the second baffle 3 is slightly larger, which is beneficial to ensure the structural strength and can receive the falling objects to prevent the pump from being stuck.

[0028] The flow holes on the steady flow baffle meet the demand of the displacement of the submersible electric pump. The flow holes are straight holes penetrating in the up-down direction, so that the rotational force of the upward rotating liquid flow discharged from the discharge port of the submersible electric pump is weakened when passing through the flow holes on the first baffle 5, and the liquid flow becomes upward flow. When the liquid in the steady flow cavity 4 continues to be lifted upward, a stable flow state is formed. The valve ball of the check valve is in a relatively stable state during production, avoiding the high-speed rotation of the valve ball under the action of rotational flow and the friction between the valve ball and the inner wall of the corresponding valve seat, thereby reducing the failure caused by rotational flow.

[0029] The oil pipe connected between the electric submersible pump 700 and the flow stabilizer 600 on the production pipe string forms a first buffer section, and the length of the first buffer section is 50 m. The oil pipe connected between the flow stabilizer 600 and the check valve 500 on the production pipe string forms a second buffer section, and the length of the second buffer section is 10 m. The first buffer section is used to slow down the rotational flow generated when the electric submersible pump 700 is in production. The flow stabilizer 600 can rectify the rotational flow which has been preliminarily weakened. The rectified flow passes through the second buffer section and enters the check valve 500, and at this time, the flow is more stable. The two rectifying baffles of the flow stabilizer 600 rectify the flow twice, and the buffer sections buffer the flow. The upward rotational flow generated when the electric submersible pump 700 lifts the liquid is changed into stable upward flow which is close to laminar flow, and the damage of the rotational flow to the accessories such as the check valve 500 on the production pipe string of the electric submersible pump is reduced.

[0030] In other embodiments, only one flow stabilizing baffle can be provided. In order to ensure the flow stabilizing effect, the thickness of the flow stabilizing baffle can be appropriately increased.

[0031] In other embodiments, the hole diameter of the flow holes on the upstream baffle can be the same as the hole diameter of the flow holes on the downstream baffle.

[0032] In other embodiments, the sum of the cross-sectional areas of the flow holes of the downstream baffle can be equal to the sum of the cross-sectional areas of the flow holes of the upstream baffle.

[0033] In other embodiments, the number of the flow holes on the downstream baffle can be greater than the number of the flow holes on the upstream baffle, and the size of the downstream baffle can meet the needs of the arrangement of the flow holes.

[0034] In other embodiments, the thickness of the upstream baffle can be equal to or greater than the thickness of the downstream baffle.

[0035] In other embodiments, the cross-sectional area of the flow stabilizing cavity can be 2 times, 3 times or 5 times the sum of the cross-sectional areas of the flow holes on the upstream baffle.

[0036] In other embodiments, the length of the first buffer section can be 40 m or 60 m, and the length of the second buffer section can be 8 m or 12 m.

[0037] Finally, it should be noted that the above description is only for the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions described in the foregoing embodiments without creative labor, or replace some of the technical features with equivalent ones. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An ESP production string comprising an ESP, characterized in that, The production string is provided with a flow stabilizing device above the electric submersible pump, the flow stabilizing device comprises a cylinder body, the cylinder body has a flow passage for the fluid discharged by the electric submersible pump, the flow passage is provided with a flow stabilizing baffle, the two side plates of the flow stabilizing baffle are opposite in the axial direction of the cylinder body, the flow stabilizing baffle is provided with a flow hole, and the center line of the flow hole extends along the axial direction of the cylinder body.

2. The ESP production string of claim 1, wherein, The flow stabilizing baffles are arranged in the axial direction of the cylinder body at intervals, and two adjacent flow stabilizing baffles are one upstream baffle upstream of the fluid flow direction and the other downstream baffle downstream of the fluid flow direction, and a flow stabilizing cavity is formed between the two adjacent flow stabilizing baffles.

3. The ESP production string of claim 2, wherein, The flow stabilizing baffle is provided with a first flow hole, the hole diameter of the first flow hole on the downstream baffle is greater than the hole diameter of the first flow hole on the upstream baffle.

4. The submersible electric pump production string according to claim 3, characterized in that: The flow stabilizing baffle is provided with a second flow hole at the center, and the first flow holes are circumferentially distributed outside the second flow hole, and the hole diameter of the second flow hole on the upstream baffle is equal to the hole diameter of the second flow hole on the downstream baffle.

5. The ESP production string of claim 2 or 3 or 4, wherein, The sum of the cross-sectional areas of the flow holes on the downstream baffle is greater than the sum of the cross-sectional areas of the flow holes on the upstream baffle.

6. The ESP production string of claim 5, wherein, The number of the flow holes on the downstream baffle is less than the number of the flow holes on the upstream baffle.

7. The ESP production string of claim 2 or 3 or 4, wherein, The thickness of the upstream baffle is less than the thickness of the downstream baffle.

8. The ESP production string of claim 2 or 3 or 4, wherein, The cross-sectional area of the flow stabilizing cavity is 3-5 times the sum of the cross-sectional areas of the flow holes on the upstream baffle.

9. The ESP production string of claim 2 or 3 or 4, wherein, The hole diameters of the flow holes on the flow stabilizing baffle upstream of the fluid flow direction are the same.

10. The ESP production string of claim 1 or 2 or 3 or 4, wherein, The production string comprises a flow valve arranged above the flow stabilizing device, a first buffer section is arranged between the electric submersible pump and the flow stabilizing device on the production string, the length of the first buffer section is 40-60 m, a second buffer section is arranged between the flow stabilizing device and the flow valve on the production string, and the length of the second buffer section is 8-12 m.

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