Abstract:
A crude oil lifting system and a method utilizing a vane pump for conveying a fluid. The crude oil lifting system comprises: an oil pipe and an oil pump connected to the oil pipe. The oil pump is the vane pump. The vane pump is provided with a cylindrical stator. The stator has arranged therein a drive shaft and a rator sleeved onto the drive shaft. The drive shaft is arranged within the stator along the direction parallel to the length of the stator. An intake plate is arranged at the lower end of the stator. A discharge plate is arranged at the upper end of the stator. The intake plate, the discharge plate, and the stator form a cylindrical cavity. The rotor is arranged between the intake plate and the discharge plate. An intake opening for taking in the crude oil is arranged on the intake plate. A discharge opening for discharging the crude oil is arranged on the discharge plate. The method utilizing the vane pump for conveying the fluid performs lifting by taking in and discharging the fluid in the directions of the ends of the stator.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is an U.S. National Stage application under 35 USC 371, which claims the priority to international application no. PCT/CN2012/083314, filed Oct. 22, 2012, which claims the benefit of Chinese patent application No. 201210054052.8 filed Mar. 2, 2012. The entire disclosures of the aforesaid international application no. PCT/CN2012/083314 and Chinese patent application No. 201210054052.8 are hereby incorporated by reference herein. 
     
    
     FIELD 
       [0002]    The present invention relates to a field of crude oil lifting system, which belongs to a crude oil lifting system using a vane pump, in the oil well in the petroleum industry, in particular, to a crude oil lifting system and a method for conveying fluid using a vane pump. 
       BACKGROUND 
       [0003]    Nowadays, there are following ways of lifting used in the oil field: beam pumping unit, screw pump, electric submersible pump and gas lift, each of them has unique advantages, but has distinct defects: the beam pumping unit is durable, but has a lot of transmission nodes, in which there are not only second stage deceleration of the reduction gear box, but also four-link transmission and donkey head motion, the maximum transmission efficiency is 70%-75%, the efficiency of the system is poor and the energy cost is great; the transmission mechanism of the screw pump ground lift pump is simple, and commonly separated into two stage deceleration motion, the efficiency thereof is higher, and the ground efficiency is typically 88%-92%, which is much higher than the beam pumping unit. However, the stator of the screw pump is rubber, which is difficult to undertake the high temperature lifting working condition of the heavy oil well. Moreover, as the time of oil exploration passes, the water content, sand content and gas content in the crude oil gradually increases, the high temperature exploration working condition becomes more frequently, and the existing lifting technique is no longer fulfill the requirement of high temperature lifting and energy conservation. 
         [0004]    The vane pump is a displacement pump, and is wildly used in the fields of hydraulic power steering system for vehicle, machine tool, construction machinery and etc., it has advantages of strong self-priming capability, compact structure, higher working pressure, low flow pulsation and high volumetric efficiency. Today&#39;s industrial vane pump uses radial suction and discharge, such that the direction of suction and discharge tends to be perpendicular to the rotation shaft of the vane puom, after connecting the direction of suction and discharge to the pipe line of the suction and discharge, the radial dimension of the vane pump is increased, causing the volume of vane pump is relatively large, which is difficult to adapt to the narrow tube-shaped space. For example, the Japanese patent JP1-177478A and Chinese patent CN2379622Y both use bypass structure of radial suction and discharge, these two types of bypass structure of radial suction and discharge require a very large radial dimension to achieve the displacement and pressure to lift fluid (e.g. lift crude oil), and cannot be arranged in a casing pipe of limited dimension. Also, if it will descend in the well to lift the crude oil, due to the bypass structure of radial suction and discharge used in the above existing vane pump, the radial arranged suction and discharge pipe line will be damaged during the descending in the well, and it is hard to install the vane pump safely and stably under the well. It is hard for the radially arranged suction and discharge pipe line to undertake the enormous pressure and corrosion under the well, and it cannot operate under the working condition of submersion of the crude oil. Thus, the bypass structure of radial suction and discharge limits the application of under-well lifting for the vane pump. 
         [0005]    Moreover, In order to improve the transfer capability of the vane pump, it always needs to increase the rotation speed of the prime mover. However, the speed of prime mover of the vane pump is hard to be increased due to the radiation condition and the limitation of many situations. Although the stator of the regular vane pump is metal (e.g. made from stainless steel), above characteristics restrict the vane pump to the application in some industrial field, in particular, it is difficult to be applied in the conventional field of the lifting work in the oil field. 
       SUMMARY 
       [0006]    The present invention is intended to meet the lifting requirement of high temperature well and regular well by utilizing the vane pump&#39;s advantages of high temperature durability, compact structure and high volumetric efficiency in order to obtain the objective of high temperature lifting and energy conservation. Also, the present invention is intended to solve the problems of small lifting force and large radial dimension of the existing vane pump. 
         [0007]    To this end, the present invention proposes a crude oil lifting system for lifting the crude oil in the oil well, said crude oil lifting system comprises a oil pipe and a oil well pump connected with said oil pipe, said oil well pump is a vane pump, said vane pump has a tube shaped stator, in which is provided a driving shaft, said driving shaft is arranged in the stator parallel to the length direction of the stator, and encases a rotor on the driving shaft; at the lower end of said stator is provided a suction disc, and at the upper end of said stator is provided a discharging disc, said suction disc, discharging disc and said stator form a tube shaped inner chamber, said rotor is located between the suction disc and the discharging disc, a suction inlet for sucking crude oil is arranged on said suction disc, and a discharge outlet for discharging crude oil is arranged on said discharging disc. 
         [0008]    Further, said rotor is provided with vanes along the circumferential direction, said vanes contact seal the inner chamber of the stator, said vane pump also includes a tube shaped pump case arranged to encase the outside of the stator, said suction disc and discharging disc are respectively provided with a shaft hole through which said driving shaft pass, a bearing is provided in said shaft hole, said suction disc and discharging disc both are located in the pump case and are respectively connected to the driving shaft via bearing. 
         [0009]    Further, said oil pipe is arranged in the oil layer casing pipe of the oil well, said vane pump is connected under said oil pipe, and is anchored on the inner wall of the oil layer casing pipe through an anchored. 
         [0010]    Further, said crude oil lifting system also comprises a Christmas tree provided at the well head of the oil well, a driving head supported and fixed on the Christmas tree and located on the top of the oil pipe, a sucker rod reaching into said oil pipe and connected between the driving head and the driving shaft of said vane pump. 
         [0011]    The present invention also proposes another crude oil lifting system, which comprises a oil pipe and a oil well pump connected to the oil pipe, said oil well pump is a vane pump, said vane pump comprises a plurality of tube shaped stators successively engaged with one another from bottom to top according to a direction from head to tail, a driving shaft provided through the plurality of stators parallel to the length direction of the plurality of stators, at the lower end of each said stator is provided with a suction disc, and at the upper end of each stator is provided with a discharging disc, each said stator forms a tube shaped inner chamber with adjacent suction disc and discharging disc, in each inner chamber is provided with a rotor encasing said driving shaft, said rotor is located between said suction disc and said discharging disc, on said suction disc is arranged a suction inlet for sucking crude oil, and on said discharging disc is arranged a discharging outlet for discharging crude oil, wherein between the two adjacent stators, the discharging disc for a lower stator simultaneously acts as the suction disc for the upper stator, and the discharging outlet for the lower stator simultaneously acts as the suction inlet for the upper stator, said vane pump has a channel for conveying fluid from bottom to top, and the channel for conveying fluid is located in the inner chamber of each said tube shaped stator. 
         [0012]    Further, each said rotor is provided with vanes along the circumferential direction, in each said stator, said vanes contact seal the inner chamber of said stator, said vane pump also includes a tube shaped pump case arranged to encase the outside of the plurality of stators, each said suction disc and discharging disc are respectively provided with a shaft hole through which said driving shaft pass, in each said shaft hole provided with a bearing, each said suction disc and discharging disc are all located in the pump case and are respectively connected to the driving shaft via a bearing. 
         [0013]    Further, said vane pump is connected under the oil pipe, and is anchored on the inner wall of the oil layer casing pipe through an anchored. 
         [0014]    Further, said crude oil lifting system also comprises a Christmas tree provided at the well head of the oil well, a driving head supported and fixed on the Christmas tree and located on the top of the oil pipe, a sucker rod reaching into said oil pipe and connected between the driving head and the driving shaft of said vane pump. 
         [0015]    Further, each said stator has two suction inlets and two discharging outlets. 
         [0016]    Further, the number of said stators is two. The two stators are successively engaged. 
         [0017]    The present invention also proposes a method for conveying fluid using vane pump, said vane pump has a tube shaped stator, in said stator is provided with a driving shaft, said method for conveying fluid using vane pump carries out the suction and discharging of the fluid from the end direction of said stator so as to perform lifting. A plurality of tube shaped stators are arranged in said vane pump, and are successively engaged from bottom to top according to a direction from head to tail, each said stator performs the suction and discharging of fluid from the end direction of said stator in order to perform lifting, the fluid is sucked into the vane pump by the lowest stator and discharged out of the vane pump by the highest stator, between two adjacent stators, the fluid discharged from the lower stator is sucked into the upper stator, the fluid sucked by the upper stator is sucked in the stator above the upper stator such that a suction and discharging relay is formed until the fluid sucked is discharged by the highest stator. 
         [0018]    Further, each said stator has two suction inlets for sucking fluid and two discharging outlet for discharging fluid. 
         [0019]    The present invention performs suction and discharging of fluid (e.g. crude oil) from the end direction of said stator, through the rotation of the rotor, the volume of the chamber formed by the vane and the stator continuously changes, which forms the a communication of suction inlet of vane pump with low pressure chamber in the stator, and a communication of discharging outlet with high pressure chamber, then a pressure difference thus is formed between the suction inlet of the vane pump and the discharging outlet of the vane pump such that the pumping of fluid is achieved. 
         [0020]    The present invention performs the suction and discharging of the fluid from the end direction of said stator, during the boost or the pumping of the fluid, the present invention also brings about the change of fluid potential energy due to the height difference present between the suction inlet of the vane pump and the discharging outlet of the vane pump, when the suction inlet of the vane pump and the discharging outlet of the vane pump are arranged at the end of the pump case, it maximizes the changing effect of the vane pump on the fluid potential energy, in particular it can carry out the improvement of potential energy. Comparing to the conventional arrangement in which the suction inlet of the vane pump and the discharging outlet of the vane pump are arranged at lateral of the pump case and the height difference between the suction inlet of the vane pump and the discharging outlet of the vane pump is not obvious such that it cannot affect the change of fluid potential, a great improvement is made by the present invention which makes the vane pump has not only a function of boost or pumping but also a higher lifting capability such that the vane pump may be not only limited to be used in the situations such as oil discharging at oil tanker dock, cargo oil on shipboard, cargo sweeping, unloading railroad tanker and so on, and in the oil transferring of tank truck, refueller and oil depot, fuel station, but also to be applied in any situations require for a lifting. 
         [0021]    The present invention avoids the arrangement that the stator laterally performs the suction and the discharging of the fluid, decreases the radial dimension and radial volume of the vane pump, and is capable of adapting to narrow tube shaped space, extending the range of application of vane pump. Since the channel conveying the fluid is located in the inner chamber of the pump case, there is no need to arrange the suction and discharging pipe line radially arranged in the prior art. Thus the present invention has solved the defects that the existing bypass type vane pump is hard to be installed safely and stably under the well due to the radially arranged suction and discharging pipe line, and is hard to undertake the enormous pressure and corrosion under the well, and cannot be operated under the working condition of submersion of the crude oil. By the protection of pump case or pump tube, the present vane pump performs lifting and boost while comprehensively improves such that the structure has advantages of sand resistance, gas resistance, corrosion resistance and pressure durability, capability of working under the submersion working condition, continuously lifting unattended around the clock thus the way of lifting crude oil is extended, and a better high temperature durability than other ways of lifting. 
         [0022]    Further, the channel conveying the fluid is located in the inner chamber of the stator, comparing to the radial arranged suction and discharging pipe lin for conveying fluid in the existing bypass type vane pump, the present invention avoids the conveying the fluid to the radially arranged suction and discharging pipe line by centrifugation, reducing the loss in the liquid conveying efficiency. By internal conveyation, especially the way of axial conveyation, the flow rate and pressure of the conveyation is increased. Moreover, by the internal conveyation other than bypass type radial suction and discharge, the present invention reduces the path for conveying fluid, reducing the liquid transmission loss, reducing the loss of pressure and flow rate of the liquid in the radial direction. Also, the direction of suction and discharging of the present invention is substantially straight or the direction of suction and discharging is in axial direction, the loss in speed and efficiency is small. By contrast, in the bypass type suction and discharge in the prior art, fluid significantly changes in the direction of suction and discharging, thus the bypass type suction and discharge results in more loss in speed and efficiency. 
         [0023]    The present invention carries out a boost relay for the multiple stage vane pump by arranging successively a plurality of stators utilizing the suction and discharging of the pumping fluid from the end direction, which makes it more benefit to the fluid conveyation in the tube and lifting work. This multiple stage double action vane pump is capable of significantly increasing the displacement of the vane pump, in particular is adapted to the narrow space under the well, and can greatly improve the lifting capability of the vane pump, which makes it possible for the vane pump to be applied in the forbidden field of conventional vane pump, for example lifting of fluid comprising oil exploitation, extending the field of application for the vane pump. 
         [0024]    The further effect of the present invention is as follows: 
         [0025]    (1) the vane pump in the present lifting system is totally made from metal, thus can be adapted to high temperature stimulation well and steam flooding well; 
         [0026]    (2) the oil pump has a small volume and a short pump body, thus the present invention is adapted to the inclined well and the well that had relatively big dogleg angle; 
         [0027]    (3) the present system uses driving head to drive on the ground, having advantages of high transmission, energy conservation and being adapted to light oil well, heavy oil high temperature well, gas content well, deep well and inclined well and so on. 
         [0028]    (4) the vane pump of the present invention can work at the condition where the crude oil comprises 30%-50% of gas. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0029]    The specific example of the present invention will be further described by the following examples and appending drawings, in which: 
           [0030]      FIG. 1  is a structure schematic view illustrating the crude oil lifting system according to an example of the present invention; 
           [0031]      FIG. 2  is a structure schematic view illustrating the cross section of the vane pump according to an example of the present invention from a main perspective (vanes are not shown); 
           [0032]      FIG. 3  is structure schematic view illustrating a cross section of the vane pump according to an example of the present invention in a direction perpendicular to the driving shaft; 
           [0033]      FIG. 4  is a structure schematic view illustrating the cross section of another vane pump according to an example of the present invention from a main perspective (vanes are not shown); 
       
    
    
       [0034]    Illustration of the reference sighs:
     1  pump tube     2  discharging disc     3  bearing     4  stator     5  rotor     6  key     7  suction disc     8  pump shaft (driving shaft)     9  vane     10  driving head     11  Christmas tree     12  casing pipe     13  oil pipe     14  sucker rod     15  vane pump     16  anchor     17  oil layer     27  partition     41  upper stator     43  lower stator     100  pump tube     21  suction inlet     71  discharging outlet     271  fluid transiting opening     51  upper rotor     53  lower rotor   
 
       DETAILED DESCRIPTION 
       [0061]    In order to more clearly understand the technical features, objective and effect of the present invention, reference is made of drawings to illustrate the specific embodiment of the present invention. 
         [0062]    As shown in  FIG. 1 , the present invention proposes a crude oil lifting system for lifting the crude oil in the oil well, said crude oil lifting system comprise an oil pipe  13  provided in oil well casing pipe  12 , an oil well pump connected with said pipe tube  13  is a vane pump  15 . 
         [0063]    As shown in  FIGS. 2 and 3 , the first vane pump of the present invention has a tube shaped stator  4 , a driving shaft  8  (also called as pump shaft) is provided in said stator  4 , said driving shaft  8  is arranged parallel to the length direction of said stator  4  in said stator  4  and encases the rotor  5  on said driving shaft  8 ; the lower end of the stator  4  is provided with a suction disc  7 , the upper end of said stator is provided with a discharging disc  2 , said suction disc  7 , said discharging disc  2  and said stator  4  form a tube shaped inner chamber, said rotor  5  is located between said suction disc  7  and said discharging disc  2 , a suction inlet  71  for sucking crude oil is provided on said suction disc  7 , and a discharging outlet  21  for discharging crude oil is provided on said discharging disc  2 . 
         [0064]    Said suction disc  7  and said discharging disc  2  present in a discoid shape, e.g. in a flat discoid shape, which can respectively serve as lower end cover and upper end cover for the stator  4 . The first vane pump of the present invention differs from the vane pump of the prior art mainly in that both the suction inlet and the discharging outlet of the vane pump in the present invention are arranged in the end direction of the stator, i.e. the suction inlet  71  and the discharging outlet  21  are arranged on the end cover, and present in long arc straight hole, which can be connected to the inner chamber of the stator. While both the suction inlet and the discharging outlet of the vane pump in the prior art are arranged on the lateral side of the stator, the first vane pump of the present invention may have the same structure as the prior art in other aspects. For example, with respect to the shape of the stator, of the driving shaft, of suction inlet and discharging outlet, of end cover in the vane pump, the shaft seal and bearing support of the vane pump and the connection relation between above parts in the vane pump, the suction inlet that may be connected to the pipe line, the discharging inlet that may be connected to the pipe line, and the working principle of suction at low pressure while discharging at high pressure, they are not the focus of the present invention. Above structure and working principle present in the invention may refer to and use the suitable structure of various vane pump in the prior art. For example, with respect to the suction inlet of the vane pump may be connected or in communication with the low pressure chamber of the pump case, said discharging outlet of the vane pump may be connected or in communication with the high pressure chamber of the pump case, the sealed chamber that may be formed by connecting the stator, the suction disc  7  and the discharging disc  2  and fixed by positioning pin, sealing ring and etc., all of above may be the same with the prior art. 
         [0065]    The vane pump of the present invention sucks the low pressure fluid from the suction inlet  71  on the bottom of the vane pump, changing the volume due to the rotation of the rotor of the vane pump, causing the pressure difference between the sucked fluid and the discharged fluid, and discharges high pressure fluid from the top cover, i.e. the discharging outlet  21  on the discharging disc  2  of the vane pump. Thus, the present invention completely avoids the defects of sucking and discharging fluid from the lateral of the pump case, reducing the radial dimension and radial volume, capable of adapting to narrow tube shaped space, expanding the field of application of the vane pump. The present invention is not limited to sucking and discharging fluid only from the top cover, as long as method for sucking and discharging fluid from the end direction of the stator performs pumping, regardless that the vane pump is provided with end cover, and that fluid pass through the cover, the present invention can achieve the suction and discharging of the fluid in the end direction. Normally, the direction of the suction and discharging of the fluid is in consistent with or close to the axial direction of the driving shaft  8 . Thus, the vane pump of the invention can be called as axial flow vane pump, as long as the suction and discharging of the fluid is in the end direction, regardless of the angle between the direction of the suction and discharging of the fluid and the driving shaft, for example the angle that may be intersected with the axial direction of the driving shaft  8  is 15 degree, 30 degree, 60 degree and etc., which all of these angles are distinctly differs from the bypass type structure of the suction and discharging of fluid from the lateral of the existing pump case, it is only when the direction of suction and discharging of the fluid is in consistent with or close to the axial direction of the driving shaft  8 , the vane pump of the present invention has a more compact structure. 
         [0066]    As shown in  FIGS. 2 and 3 , both the number of suction inlet  71  and the number of discharging outlet  21  is two, the two suction inlets  71  are axial symmetry to each other relative to the driving shaft  8  and are arranged on the suction disc  7 , the two discharging outlets  21  are axial symmetry to each other relative to the driving shaft  8  and are arranged on the discharging disc  2 , the suction inlet  71  and the discharging outlet  21  are arranged on the circumferential direction with a interval of 90 degree, double action vane pump is thus obtained. The double action vane pump performs suction and discharging both 2 times during one rotation of the driving shaft. Since the structure is symmetric to the force load, the double action vane pump tends to obtain more displacement, at the same time decreasing the noise of the vane pump, improve the reliability of the parts such as the driving shaft. Of course, the number of the suction inlet  71  and the number of the discharging outlet  21  both is one, the suction inlet  71  is arranged on the suction disc  7  and the discharging outlet  21  is arranged on the discharging disc  2 , the circumferential angle interval between the suction inlet and discharging outlet is 180° C. so as to coordinate with the connection between the suction inlet and the low pressure chamber of the stator, and the connection between the discharging outlet and the high pressure chamber of the stator. The vane pump performs suction and discharging one time during one rotation of the driving shaft, known as single action vane pump. The number of suction inlet  71  and discharging outlet  21  arranged is either one or two, that depends on the displacement of the lifting. 
         [0067]    Further, as shown in  FIG. 3 , said rotor  5  is provided with vanes  9  along the circle, said vanes  9  contact seal the inner chamber of the stator  4 , said vane pump also includes a tube shaped pump case  1  arranged to encase the outside of the stator, as shown in  FIG. 2 , said suction disc  7  and discharging disc  2  are respectively provided with shaft hole through which said driving shaft  8  passes, a bearing  3  is provided in said shaft hole, said suction disc and discharging disc both are located in the pump case  1  and are respectively connected to the driving shaft  8  via bearing  3 . The arrangement of pump case is favorable to the sealing of the vane pump, stability of the lifting and the decrement of the noise. The vane pump may utilize a eccentric chamber structure for the stator or the pump case, the outline of the stator or the pump case may be a symmetric ellipse shape or approximate ellipse shape, the outline may be multiple curvilinear equation, the sealed chamber that may be formed by connecting the stator, the suction disc  7  and the discharging disc  2  and fixed by positioning pin, sealing ring and etc., and the positioning relation between the stator and the pump case, both may use the technique in the prior art. However, the present invention is not limited to eccentric chamber for the stator or the pump case, and to the rotor and vane structure, it may also use the coordination of multiple stators or pump cases with the rotor in the prior art. 
         [0068]    The present invention also proposes a second crude oil lifting system, said crude oil lifting system comprises a oil pipe, oil well pump connected with said oil pipe, said oil well pump is a vane pump. The second crude oil lifting system mainly differs from the first crude oil lifting system in that, the vane pump of the second crude oil lifting system is a multiple stage pump formed by a plurality of stators, between the adjacent stators, the fluid discharged from the lower stator is sucked into the upper stator, the discharging disc for the lower stator simultaneously acts as the suction disc for the upper stator, the discharging outlet for the lower stator simultaneously acts as the suction inlet of the upper stator. This vane pump is a multiple stage vane pump, in each stage of the pump or each stator can form a boost effect by low pressure suction and high pressure discharging in a single stage pump as shown in  FIGS. 2 and 3 , and in  FIG. 4  is shown a two stage vane pump. 
         [0069]    As shown in  FIG. 4 , the vane pump of the second crude oil lifting system comprises a plurality of tube shaped stators, for example the upper stator and the lower stator  43 , a driving shaft  8  provided through the plurality of stators parallel to the length direction of the plurality of stators, at the lower end of each said stator is provided with a suction disc, at the lower end of the lower stator  43  is provided with a suction disc  7 , on said suction disc  7  is provided with a suction inlet  71  for sucking crude oil, at the lower end of the upper stator is provided with a partition  27 , on the partition  27  is provided with a fluid transiting opening  271 , the partition  27  is served as the suction disc for the upper stator, and the fluid transiting opening  271  is served as a suction inlet for the upper stator. 
         [0070]    The upper end of the each said state is provided with a discharging disc, the upper end of the upper stator  41  is provided with a discharging disc  41 , said discharging disc is provided with a discharging outlet  21  for discharging crude oil, the partition  27  simultaneously acts as a discharging disc for the lower stator  43 , and the fluid transiting opening  271  is served as a discharging outlet for the lower stator  43 . The partition divides the upper stator  41  and lower stator  43  into two separate inner chambers, these two stators or inner chambers are linked with each other by fluid transit opening  271 , the fluid is sucked into the lower stator  43 , subjected to the first boost, then discharged from fluid transit opening  271  into the upper stator  41 , subjected to the second boost by the upper stator  41 , then discharged from the upper stator  41  through the discharging outlet  21 . Thus is obtained the two stage boost as well as the two stage vane pump. If a boost multiple for the single stage vane pump is m, then the whole boost multiple for the vane pump is m squared after the boost of two stage axial flow vane pump, and the whole boost multiple is m cubed after three stage boost, and the whole boost multiple is m to power of n after n stage boost, it is possible to achieve a boost relay for the multiple stage axial flow vane pump by above design, and the effect thereof is significant. 
         [0071]    As shown in  FIG. 4 , the number of the fluid transit opening  271  is two, and the partition  27  may be the same shape and structure with the suction disc and the discharging disc. However, the fluid transit opening  271  on the partition  27  has a angle interval of 90° to the circumferential direction of adjacent suction inlet and discharging outlet so as to ensure that in each stator, the suction inlet is connected with the low pressure chamber of the stator, and the discharging outlet is connected with the high pressure chamber of the stator, as the single stage vane pump shown in  FIGS. 2 and 3 . Each stator inner chamber has an eccentric chamber with the same shape, along the circumferential direction, the arrangement directions of two adjacent pump cases are perpendicular to each other so as to coordinate with the connection between the suction inlet and the lower pressure chamber of the stator, and the connection between the discharging outlet and the high pressure chamber of the stator. Of course, the number of the suction inlet  71  and the number of the discharging outlet  21  both may be one, the suction inlet  71  is arranged on the suction disc  7 , and the discharging outlet  21  is arranged on the discharging disc  2 , the number of the fluid transit opening  271  is  1 , the fluid transit opening  271  on the partition  27  has a angle interval of 180° to the circumferential direction of adjacent suction inlet and discharging outlet. The vane pump sucks and discharges one time during one rotation of the driving shaft. The number of suction inlet  71  and discharging outlet  21  arranged is either one or two, which depends on the displacement of the lifting. 
         [0072]    In  FIG. 4 , two said stator are successively engaged with each other from bottom to top according to a direction from head to tail, each said stator and adjacent suction disc and discharging disc form a tube shaped inner chamber, in each inner chamber is provided with a rotor encasing said driving shaft, said rotor is located between said suction disc and said discharging disc. According to  FIG. 4 , it can be envisaged that two or more partitions are arranged to form three stage pump or more stage pump. Since different well depth requires different discharging pressure, that is, the deeper is the well, the larger is the pressure required, thus more stage is required for the pump according to the theory of pressure gradient of pump in series, and it is possible for this multiple stage vane pump to be adapted to the use of the deep well. 
         [0073]    Further, as shown in  FIG. 1 , said vane pump  15  is connected under said oil pipe  13 , the outlet of the pump tube is in communication with the oil pipe, and the pump tube is connected with the oil pipe via an oil pipe buckle, the connection of the pump tube and the oil pipe may utilize various suitable manner in the prior art. Said vane pump is anchored on the inner wall of the oil layer casing pipe  12  through an anchor  16 , the lower end of the anchor  16  and the pump tube of the vane pump  15  is provided with an oil pipe buckle, the vane pump  15  is directly connected to the anchor by the oil pipe buckle, the anchor  16  fixes vane pump to ensure that the pump case does not rotate when the pump is in operation. 
         [0074]    Further, as shown in  FIG. 1 , said crude oil lifting system also comprises a Christmas tree  11  provided at the well head of the oil well, a driving head  10  as a driving part for rotation of the well head of the oil well, comprising a electric motor, decelerator etc, and supported and fixed on said Christmas tree  11  and located on the top of said oil pipe, for driving the rotation of a sucker rod; sucker rod  14  reaching into said oil pipe  13  and connected between said driving head  10  and the driving shaft  8  of said vane pump. The driving head  10  drives the rotation of the sucker rod  14 , pump shaft  8 , rotor  5  and vane  9  when the driving head  10  rotates. The pump shaft  8  (also known as driving shaft) is under the power transmission, driving the rotation of the vane  9  on the stator  2  in the working chamber, the inner chamber of the stator  2  presents an ellipsoid and forces the vane  9  to move radially. The crude oil is sucked through a pore channel in the suction disc  7  when the vane rotates toward the large chamber section (low pressure chamber), and the crude oil is discharged through a pore channel in the discharging disc  2  when the vane rotates toward the small chamber section (high pressure chamber). Since the rotor continuously rotates, the crude oil is continuously sucked and discharged. The crude oil in the oil layer  17  under the well is conveyed to the ground Christmas tree through the oil pipe  14 , and then is distributed to crude oil metering station and storage station. The pump shaft differs in theory from plunger pump, electric submersible centrifugal pump and screw pump in the prior art. 
         [0075]    The present invention also proposes a method for conveying fluid using vane pump, said vane pump has a tube shaped stator, in said stator is provided with a driving shaft, said method for conveying fluid using vane pump carries out the suction and discharging of the fluid from the end direction of said stator so as to perform lifting. As shown in  FIGS. 1 to 4 , the present invention is not limited to sucking and discharging fluid only from end cover (i.e. suction disc and discharging disc), the present invention can convey the crude oil from upper end to lower end. As long as the method for sucking and discharging fluid from the end direction of the stator performs pumping, regardless that the vane pump is provided with end cover, that the fluid pass through the cover or the suction disc and the discharging disc, and that the cover is flat or arc, the present invention can achieve the suction and discharging of the fluid in the end direction. Normally, the direction of the suction and discharging of the fluid is in consistent with or close to the axial direction of the driving shaft  8 . Thus, the vane pump of the invention can be called as axial flow vane pump, as long as the suction and discharging of the fluid is in the end direction, regardless of the angle between the direction of the suction and discharging of the fluid and the driving shaft, for example the angle that may be intersected with the axial direction of the driving shaft  8  is 15 degree, 30 degree, 60 degree and etc., which all of these angles are distinctly differs from the bypass type structure of the suction and discharging of fluid from the lateral of the existing pump case, it is only when the direction of suction and discharging of the fluid is in consistent with or close to the axial direction of the driving shaft  8 , the vane pump of the present invention has a more compact structure. 
         [0076]    Further, as shown in  FIG. 4 , a plurality of tube shaped stators are arranged in said vane pump, and are successively engaged from bottom to top according to a direction from head to tail, each said stator performs the suction and discharging of fluid from the end direction of said stator in order to perform lifting, the fluid is sucked into the vane pump by the lowest stator and discharged out of the vane pump by the highest stator, between two adjacent stators, the fluid discharged from the lower stator is sucked into the upper stator, the fluid sucked by the upper stator is sucked in the stator above the upper stator such that a suction and discharging relay is formed until the fluid sucked is discharged by the highest stator. Through above design, the boost relay of the multiple stage axial flow vane pump can be obtained, the boost and relay of pumps between stages can be achieved. Comparing to multiple single stage pump in series, the multiple stage axial flow vane pump has advantages of simple structure, lower cost and significant boost effect. 
         [0077]    Above description is only intended to schematically illustrate the specific embodiment of the present application, and is not used to limit the scope of the present invention. Any part of the present invention may be combined together under the condition that they do not contradict themselves, any equivalent modification or variation made by any person skilled in the art without departing the spirit and principle of the present invention falls into the scope of protection of the present invention.