Immersed pump for increasing yield of shale oil

Abstract

The utility model relates to an immersed pump for increasing the yield of shale oil, and belongs to the technical field of oil and gas exploitation equipment. The device comprises a submersible motor, a multi-stage centrifugal pump and an axial force self-balancing device. The core structure is that the upper end and the lower end of the multi-stage centrifugal pump are respectively provided with an upper diversion pressure plate and a lower diversion pressure plate which are connected through a connecting column; and the submersible motor is wrapped in an upper flow guide shell connected with the upper flow guide pressure plate to form a forced cooling flow channel. High-pressure liquid discharged by the multi-stage centrifugal pump flows through the flow channel to cool the motor, and meanwhile, the high-pressure liquid acts on the balance disc at the water outlet end of the pump to generate reverse thrust so as to automatically balance axial force generated by the impeller set. Through innovative structural layout and self-balancing design, the running reliability of the pump is remarkably improved, and the service life of the pump is remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to a submersible pump for shale oil production increase belongs to oil and gas exploitation equipment technical field. BACKGROUND

[0002] The electric submersible pump becomes the first artificial lifting way of the shale oil well production initial stage to realize "production increase" and commercial development because of its large displacement and high lift characteristics. However, in the in-depth research of the inventor to the shale oil field site application, it is found that the electric submersible pump of the prior art has the following two bottleneck problems of restricting its performance and life under the specific scene of "shale oil production increase":

[0003] The huge axial force caused by "production increase" leads to the premature failure of the thrust bearing: in order to realize high yield, the electric submersible pump for shale oil usually needs to be designed with extremely high stages (up to hundreds of stages) and high speed to provide huge lifting power. This leads to the axial force generated by all impellers to be superimposed, forming a huge thrust of tens of tons even hundreds of tons pointing to the pump suction inlet. The thrust is completely borne by the thrust bearing at the top end of the submersible motor. More seriously, a large amount of high-hardness quartz sand proppant carried in the fracturing flowback fluid will invade the bearing, like an abrasive, and aggravate its wear. Therefore, under the dual action of "excessive axial force" and "abrasive wear", the thrust bearing often fails in a short period of time, which is the primary cause of the scrap of the entire expensive electric submersible pump unit and the huge economic loss.

[0004] The high-power operation of the "production increase" stage poses a severe challenge to the heat dissipation of the motor: the high-yield liquid of the shale oil well corresponds to the super-high power submersible motor needed to drive the electric submersible pump. The motor operates at full load in the high-temperature environment of thousands of meters underground, which will generate a large amount of heat. The conventional electric submersible pump only relies on the natural upward flow of the production liquid in the wellbore to cool its shell, and this passive cooling method has limited effect. Especially in the case of reduced production, reduced flow rate or irregular expansion of the wellbore, the cooling effect will deteriorate sharply. Once the motor is poorly cooled, it is easy to fail due to the aging of the winding insulation layer and burnout, resulting in unexpected interruption of the "production increase" process. UTILITY MODEL CONTENTS

[0005] The utility model wants to solve the technical problem: overcome the prior art's insufficient, provide a submersible pump for shale oil production increase,

[0006] The utility model discloses a submersible pump for shale oil production increase, including: including from top to bottom the submersible motor and the multistage centrifugal pump of the multiple pump stages series connection, the multistage centrifugal pump includes multiple impellers and flow guide shell, the impeller is driven to be connected with the submersible motor through the pump shaft;

[0007] Still include an axial force self-balancing device that sets up in the multistage centrifugal pump outlet water end;

[0008] The axial force self-balancing device comprises a balance disc rotating synchronously with the pump shaft and a balance channel for connecting a balance chamber formed behind the balance disc with a low-pressure area outside;

[0009] The upper and lower ends of the multi-stage centrifugal pump in series are respectively provided with flow guide pressure discs, the flow guide pressure discs at the two ends are connected through connecting columns, and the flow guide pressure discs at the two ends are respectively connected with flow guide housings, wherein the water outlet accommodation cavity of the upper flow guide pressure disc is communicated with the upper flow guide housing, and the water inlet accommodation cavity of the lower flow guide pressure disc is communicated with the lower flow guide housing.

[0010] The submersible motor is arranged in the flow guide housing connected with the upper flow guide pressure disc, so that the multi-stage centrifugal pump, the upper flow guide pressure disc, the lower flow guide pressure disc and the flow guide housing are arranged in a cylindrical shape.

[0011] Further, the output end of the submersible motor is connected with a main shaft, the impeller is keyed on the main shaft, the balance disc is sleeved on the outer periphery of the impeller, and the flow guide housing is sleeved on the outer periphery of the balance disc.

[0012] Further, the upper flow guide pressure disc and the lower flow guide pressure disc are respectively connected with support frames, the support frame on the upper flow guide pressure disc is used for connecting the submersible motor, and the support frame on the lower flow guide pressure disc is used for connecting the cyclone gas separator.

[0013] Further, the flow guide pressure disc is provided with uniformly annularly distributed connecting holes, the connecting holes are used for penetrating the connecting columns so as to connect the upper flow guide pressure disc and the lower flow guide pressure disc.

[0014] Further, a through hole is arranged between the two connecting holes, the through hole is used for connecting the water outlet accommodation cavity of the upper flow guide pressure disc with the upper flow guide housing, or the through hole is used for connecting the water inlet accommodation cavity of the lower flow guide pressure disc with the lower flow guide housing.

[0015] Further, the impeller comprises two fixed discs arranged in parallel, blades are arranged between the two fixed discs, and a suction channel is reserved on one side fixed disc.

[0016] Further, the balance disc comprises a collection cavity arranged on the outer periphery, the collection cavity is communicated with the balance chamber, guide vanes are arranged on the one end surface of the balance disc in correspondence with the collection cavity.

[0017] Compared with the prior art, the utility model has the beneficial effects that:

[0018] The utility model discloses introduce the abrasion -resistant axial force self -balancing device. It utilizes the high pressure liquid of pump itself, generates an opposite direction thrust that is opposite with the total axial force direction of impeller, and the size is almost equal, to thereby'inside offset' the huge axial force of several tons in hydraulic level. This makes the mechanical thrust bearing from'main bearing'become'auxiliary positioner ', and its load reduces. Even in the sand liquid, because load is sharp to reduce, its service life can also get exponential promotion, has guaranteed the long -term stable operation of'increase production'stage.

[0019] The utility model discloses ingeniously guide the high pressure, high -speed liquid of pump discharge to an annular flow passage that is wrapped motor, forms a'pump -type'forced convection cooling system. Regardless of wellbore fluid production, motor is always washed cooling by high -speed liquid, and its heat dissipation efficiency is far more than traditional natural convection mode. This has guaranteed that motor can also keep in the safe temperature range operation under the condition of'increase production'required high power, high load, and has eliminated the risk of burning because of overheating. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the structural schematic diagram of the utility model embodiment 1;

[0021] Figure 2 It is the front view of the utility model embodiment 1;

[0022] Figure 3 It is Figure 2 the full section view of A-A in;

[0023] Figure 4 It is Figure 3 the partial close -up view of B in;

[0024] Figure 5 It is the internal structure schematic diagram of the utility model embodiment 1 of guide flow shell;

[0025] Figure 6 It is Figure 5 the partial close -up view of C in;

[0026] Figure 7 It is the structure schematic diagram of the upper guide flow pressure disc of the utility model embodiment 1;

[0027] Figure 8 It is the front view of the upper guide flow pressure disc of the utility model embodiment 1;

[0028] Figure 9 It is the rear view of the upper guide flow pressure disc of the utility model embodiment 1;

[0029] Figure 10 It is the plan view of the upper guide flow pressure disc of the utility model embodiment 1;

[0030] Figure 11 It isFigure 10 Full cross-sectional view at D-D;

[0031] Figure 12 is the balance disc structure schematic view of embodiment 1 of the utility model;

[0032] Figure 13 is the impeller structure schematic view of embodiment 1 of the utility model;

[0033] Figure 14 is the impeller bottom view of embodiment 1 of the utility model;

[0034] Figure 15 is Figure 14 Full cross-sectional structure schematic view at E-E;

[0035] Figure 16 is the guide shell structure schematic view of embodiment 1 of the utility model;

[0036] In the figure:

[0037] 1, submersible motor;2, guide shell;3, multistage centrifugal pump;31, impeller;311, fixed disc;312, blade;313, suction passage;32, guide shell;33, balance chamber;34, balance passage;4, connecting column;5, lower guide pressure disc;6, upper guide pressure disc;61, connecting hole;62, through hole;63, water outlet containing cavity;7, balance disc;71, guide blade;72, collection cavity;73, water outlet;8, main shaft;9, support frame. DETAILED DESCRIPTION

[0038] Embodiment 1

[0039] As Figures 1-16 shown, the shale oil production increasing submersible pump of the utility model, including: including from top to bottom sequentially connected submersible motor 1 and by a plurality of pump stages in series multistage centrifugal pump 3, the multistage centrifugal pump 3 including a plurality of impellers 31 and guide shell 32, the impeller 31 is driven to be connected with the submersible motor 1 through pump shaft;The core component of this pump, namely multistage centrifugal pump 3, is covered and fixed by an innovative external frame.This frame is composed of a lower guide pressure disc 5 located at the lower end of pump group, an upper guide pressure disc 6 located at the upper end of pump group and a plurality of connecting columns 4 (see Figure 5 ) penetrating both and firmly tensioning them.This "frame type" structure fastens the originally segmented pump stages into a high-rigidity whole, greatly enhancing the bending resistance and vibration resistance of the pump group when being lowered into and working in long horizontal wells.

[0040] Still including an axial force self-balancing device arranged at the water outlet end of the multistage centrifugal pump 3;

[0041] The axial force self-balancing device comprises a balance disc 7 rotating synchronously with the pump shaft and a balance passage 34 for connecting the balance chamber 33 formed behind the balance disc 7 with a low-pressure area or a communication outside;

[0042] The upper and lower ends of the multi-stage centrifugal pump 3 are respectively provided with flow guide pressure discs, the flow guide pressure discs at the two ends are connected through a connecting column 4, and the flow guide pressure discs at the two ends are respectively connected with flow guide housings 2, wherein the water outlet accommodation cavity 63 of the upper flow guide pressure disc 6 is communicated with the upper flow guide housing 2, and the water inlet accommodation cavity of the lower flow guide pressure disc 5 is communicated with the lower flow guide housing 2.

[0043] The submersible motor 1 is arranged in the flow guide housing 2 connected with the upper flow guide pressure disc 6, so that the multi-stage centrifugal pump 3, the upper flow guide pressure disc 6, the lower flow guide pressure disc 5 and the flow guide housing 2 are arranged in a cylindrical shape. The submersible motor 1 as a power source is installed at the upper part of the frame and is completely covered in an upper flow guide housing 2. The upper flow guide housing 2 is sealingly connected with the upper flow guide pressure disc 6. Similarly, a lower flow guide housing 2 is sealingly connected with the lower flow guide pressure disc 5 for guiding well fluid into the suction inlet of the pump.

[0044] The output end of the submersible motor 1 is connected with a main shaft 8, the impeller 31 is keyed connected on the main shaft 8, the balance disc 7 is sleeved on the outer periphery of the impeller 31, and the flow guide housing 32 is sleeved on the outer periphery of the balance disc 7.

[0045] The upper flow guide pressure disc 6 and the lower flow guide pressure disc 5 are respectively connected with support frames 9, the support frame 9 on the upper flow guide pressure disc 6 is used for connecting the submersible motor 1, and the support frame 9 on the lower flow guide pressure disc 5 is used for connecting a cyclone gas separator. Through the support frame 9, the submersible motor 1 is accurately fixed on the upper flow guide pressure disc 6, so as to ensure the coaxiality with the main shaft 8. Meanwhile, the support frame 9 below the lower flow guide pressure disc 5 provides a standard interface for connecting other parts of the downhole tool string, preferably connecting a cyclone gas separator to cope with the high gas content problem commonly seen in shale oil wells.

[0046] The outer ring of the flow guide pressure disc is provided with uniformly annularly distributed connecting holes 61, the connecting holes 61 are used for penetrating the connecting column 4, so as to connect the upper flow guide pressure disc 6 and the lower flow guide pressure disc 5.

[0047] A through hole 62 is arranged between the two connecting holes 61, and the through hole 62 is used for connecting the water outlet accommodation cavity 63 of the upper flow guide pressure disc 6 with the upper flow guide housing 2.

[0048] The through hole 62 on the lower flow guide pressure disc 5 is used for connecting the water inlet accommodation cavity of the lower flow guide pressure disc 5 with the lower flow guide housing 2, and the position of the through hole 62 is arranged at the same position of the upper flow guide pressure disc 6 and the lower flow guide pressure disc 5 and has the same function.

[0049] The impeller 31 comprises two fixed discs 311 arranged in parallel, and blades 312 arranged between the two fixed discs 311, wherein an intake passage 313 is reserved on one side of the fixed disc 311.

[0050] The balance disc 7 comprises a collection cavity 72 arranged at an outer periphery, the collection cavity 72 being communicated with the balance chamber 33, and guide vanes 71 being correspondingly arranged on one end face of the balance disc 7, the guide vanes 71 being arranged corresponding to the collection cavity 72.

[0051] The collection cavity 72 is provided with a water outlet 73 on one side face, and water sucked by the impeller 31 enters the collection cavity 72 through the water outlet 73.

[0052] Working process or working principle:

[0053] In the "increasing production" operation, well fluid flows through the lower guide flow disc 5 into the multi-stage centrifugal pump 3 to be gradually pressurized from bottom to top after gas-liquid separation; the high-pressure liquid discharged by the pump is used to drive the balance disc 7 to offset the axial force, and most of the high-pressure liquid enters the annular flow channel through the upper guide flow disc 6 to forcibly cool the submersible motor 1; finally, the liquid is discharged from the top of the pump set. Through the ingenious design of the structure, the axial force and the motor cooling, which are two core problems restricting the performance of the shale oil electric submersible pump, are solved in one station.

[0054] Intake and pressurization process: the downhole liquid (after gas separation) first enters the lower guide shell 2, then enters the water inlet cavity in the lower guide flow disc 5 through the through hole 62 on the lower guide flow disc 5, and finally is sucked into the first stage impeller 31 of the multi-stage centrifugal pump 3 (see Figure 3 ). Under the drive of the submersible motor 1, the main shaft 8 drives all the impellers 31 to rotate at high speed, and the liquid is continuously pressurized when flowing through the "impeller 31-guide shell 32" pump stage.

[0055] Formation and work of the forced cooling flow channel: after the liquid is pressurized in the last stage, all the high-pressure and high-speed liquid is collected in the water outlet cavity 63 of the upper guide flow disc 6 (see Figure 11 ). Then, the liquid is guided into the annular flow channel formed between the upper guide shell 2 and the motor shell through the uniformly distributed through holes 62 (see Figure 10 ) on the upper guide flow disc 6. Since the entire displacement of the pump is forced to pass through this narrow annular space, a high-speed scouring flow is formed, which performs efficient forced convection heat exchange with the motor shell, thereby rapidly removing the large amount of heat generated by the motor. Finally, the liquid that has completed the cooling task flows out from the discharge port at the top end of the pump set and enters the production pipe.

[0056] The wear-resistant type axial force self-balancing device: in each stage, an annular balance disc 7 is sleeved on the outer periphery of the impeller 31. When the pump works, the high-pressure liquid discharged by the impeller 31 acts on the position of the back side of the balance disc 7 provided with guide vanes 71, and a reverse thrust is formed in the balance chamber 33. The thrust is introduced to the low-pressure area through the balance channel 34 to realize pressure balance, and the principle aims to offset the axial force generated by the impeller itself.

[0057] The description of the structure direction and relative position relationship in the utility model, such as the description of front, back, left, right, up and down, does not constitute the limitation of the utility model, and is only convenient for description.

Claims

1. A submersible pump for shale oil stimulation, comprising a submersible motor (1) and a multi-stage centrifugal pump (3) connected in series from top to bottom, the multi-stage centrifugal pump (3) comprising a plurality of impellers (31) and a guide shell (32), the impellers (31) being drivingly connected with the submersible motor (1) through a pump shaft; It also includes an axial force self-balancing device arranged at the water outlet end of the multi-stage centrifugal pump (3); The axial force self-balancing device comprises: A balance disc (7) rotating synchronously with the pump shaft and a balance channel (34) for communicating a balance chamber (33) formed behind the balance disc (7) with an external low-pressure area; Characterized in that, The multi-stage centrifugal pump (3) is provided with guide pressure discs at the upper and lower ends respectively, the guide pressure discs at the two ends are connected through a connecting column (4), and the guide pressure discs at the two ends are respectively connected with flow guide housings (2), wherein the water outlet accommodation cavity (63) of the upper guide pressure disc (6) is communicated with the upper flow guide housing (2), and the water inlet accommodation cavity of the lower guide pressure disc (5) is communicated with the lower flow guide housing (2); The submersible motor (1) is arranged in the flow guide housing (2) connected with the upper guide pressure disc (6), so that the multi-stage centrifugal pump (3), the upper guide pressure disc (6), the lower guide pressure disc (5) and the flow guide housing (2) are arranged in a cylindrical shape.

2. The downhole pump of claim 1, wherein, The output end of the submersible motor (1) is connected with a main shaft (8), the main shaft (8) is keyed with the impeller (31), the impeller (31) is sleeved with the balance disc (7), and the balance disc (7) is sleeved with the guide shell (32).

3. The downhole pump of claim 1, wherein, The upper guide pressure disc (6) and the lower guide pressure disc (5) are respectively connected with support frames (9), the support frame (9) on the upper guide pressure disc (6) is used for connecting the submersible motor (1), and the support frame (9) on the lower guide pressure disc (5) is used for connecting a cyclone gas separator.

4. The downhole pump of claim 1, wherein, The outer ring of the guide pressure disc is provided with uniformly annularly distributed connecting holes (61), the connecting holes (61) are used for penetrating the connecting column (4) to connect the upper guide pressure disc (6) and the lower guide pressure disc (5).

5. The downhole pump of claim 4, wherein, A through hole (62) is arranged between the two connecting holes (61), the through hole (62) is used for communicating the water outlet accommodation cavity (63) of the upper guide pressure disc (6) with the upper flow guide housing (2); or the through hole (62) is used for communicating the water inlet accommodation cavity of the lower guide pressure disc (5) with the lower flow guide housing (2).

6. The downhole pump of claim 1, wherein, The impeller (31) comprises two fixed discs (311) arranged in parallel, a blade (312) is arranged between the two fixed discs (311), and a suction channel (313) is reserved on one side of the fixed disc (311).

7. The downhole pump of claim 1, wherein, The balance disc (7) comprises a collection cavity (72) arranged at the outer periphery, the collection cavity (72) is communicated with the balance chamber (33), a guide vane (71) is correspondingly arranged on one end face of the balance disc (7), and the guide vane (71) is arranged corresponding to the collection cavity (72).

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