Pertinent Art

A submersible pumping unit claimed is classified as oil production equipment, namely pumps and pumping units for lifting of liquids from deep depth.

Prior Art

Prior art discloses a submersible reciprocating pumping unit with numerical control, (see EAPO patent for invention No. 009268, IPC E21B43/00, F04B47/00.)

A submersible reciprocating pumping device with the digital-programme control, comprising the lattice pipe, drive and pump; meanwhile the total device is designed to be installed in the underground oil reservoir. The drive consists of the stator and the reciprocating head with the steel cores inside the stator. The stator and the head form the friction joint due to the supporting guides and the steel head cores that is different so that, provided the air-tight cavity available, the upper end of the stator is linked to the lower end of the pump via the lattice pipe, the pump is linked to the oil pipe, the lower end of the stator is connected in sequence to the balancing lattice pipe, the end plug and the end intermediate coupling. There are many groups of circular windings of steel cores with the supporting guides between the winding groups inside the stator housing. The steel cores and the circular windings are installed near W

each other. The sealing bushes are located on the circular interior surfaces which are connected by the end covers. The air-tight cavity is formed resulting therefrom. The stator windings coiled in the radial direction are located axially. The supporting guides are 5 manufactured of the alloy. The circular interior surfaces are made of the alloy. The supporting guides have the lesser interior diameters than the sealing bushes. The steel cores of the reciprocating head are located around the solid shaft thereof with the permanent magnets between the steel cores. The exterior surfaces of the circular steel

10 cores are made of alloy. They form the friction joint with the supporting guides via the layers made of alloy on the interior surfaces of the supporting guides. The permanent magnets stand apart each other within the equal distance between the steel cores of the reciprocating head. They have the lesser exterior diameter than

15 the circular steel cores. The pump housing is located at the exterior side of the pumping cylinder which forms the circular space between those for the sand deposit, while the plunger ram is connected to the upper end of the reciprocating head shaft via the lattice pipe. The oil pipe goes to the ground surface. The stator winding output is

20 connected to the digital-programme control unit located on the surface.

The drawback of this technical solution is the insufficient heat discharge as well as the significant decrease in 25 capacity at lowering the dimensions of the pump assembly. Disclosure of the invention

The purpose of the proposed invention shall be to create a submersible pumping unit while ensuring the intensive heat discharge and the stable capacity at lowering the dimension of the device.

The task set is addressed so that the submersible pumping unit comprises the housing, the suction valve, the discharge valve, the rotor, the stator, the plunger, the cylinder and the induction coils. The plunger-cylinder pair shall be executed as a line pump. The plunger that consists of the metal pipe featuring the permanent magnets with the reciprocal poles alternating with the metal inserts shall be simultaneously the rotor of the pump unit. The rotor cylinder shall play the role of the insulating pipe. This shall be made of the alternating fused rings comprising the ferromagnetic and non-magnetic materials. The width of the rings made of the non-magnetic material in the rotor cylinder is twice larger than the same of the ferromagnetic rings, while the width of the rings comprising the permanent magnet on a metal tube is equal to the width of the non-magnetic rings comprising the rotor cylinder. The width of the rings made of the ferromagnetic material is equal to the width of the metal inserts in the metal plunger tube. The stator shall comprise the stator cylinder featuring the alternating fused rings made of the ferromagnetic and non-magnetic materials with the equal length and the induction coils enclosed into the core cases. The distance between the rotor cylinder and the stator cylinder shall be made to ensure the W

minimum clearance. The induction coils and the core cases shall be made with the circular cut-through openings located axially with all induction coils and the core cases, to which the heat pipes are installed with the one end located inside the stator and being 5 the heat receiver, while the second end is put into the flow of the drained fluid and being the heat discharger. The ends of the rotor are equipped with the valves, while the induction coils enclosed into the core cases are made so that they feature the clearances upside to output the winding and they fully cover the width of the 10 induction coils, while the core cases downside, at the point where those align to the stator cylinder, are located at the same level with the rings of the stator cylinder made of the ferromagnetic material.

Brief description of figures and drawings

The essence of the invention shall be clarified by the 15 drawings where

Fig. 1 presents a view of the submersible pumping unit in the longitudinal cross section.

Fig. 2 presents a view along AA of the submersible pumping unit in the transverse cross section.

20 Fig. 3 presents a view of the fragment being part of the longitudinal cross section of the plunger-cylinder pair.

Fig. 4 presents an axonometric projection of the elements comprising the subordinate module of the submersible pumping unit. Submersible pumping unit 1 shall comprise housing 2, suction valve 3, discharge valve 4, rotor 5, stator 6, plunger 7, cylinder 8 and induction coils 9. Plunger-cylinder pair 10 shall be executed as a line pump. Plunger 7 that consists of metal pipe 11 featuring permanent magnets 12 with the reciprocal poles alternating with metal inserts 13 shall be simultaneously rotor 5 of pump unit 1. Rotor cylinder 14 shall play the role of the insulating pipe. This shall be made of the alternating fused rings comprising ferromagnetic 15 and non-magnetic 16 materials. The width of the rings made of non-magnetic material 16 in rotor cylinder 14 is twice larger than the same of ferromagnetic rings 15, while the width of the rings comprising permanent magnet 12 on metal tube 11 is equal to the width of non-magnetic rings 16 comprising rotor cylinder 14. The width of the rings made of ferromagnetic material 15 inside rotor cylinder 14 is equal to the width of metal inserts 13 in metal tube 1 1 of plunger 7. Stator 6 shall comprise stator cylinder 17 featuring the alternating fused rings made of ferromagnetic 18 and non-magnetic 19 materials with the equal length and induction coils 9 enclosed into core cases 20. The distance between rotor cylinder 14 and stator cylinder 17 shall be made to ensure the minimum clearance. Induction coils 9 and core cases 20 shall be made with circular cut-through openings 21 located axially with all induction coils 9 and core cases 20, to which heat pipes 22 are installed with the one end located inside stator 6 and being the heat receiver, while the second end is put into the flow of the drained fluid and being the heat discharger. The ends of rotor 6 are equipped with valves 23, while induction coils 9 enclosed into core cases 20 are made so that they feature clearances 24 upside to output winding 25 and they fully cover the width of induction coils 9, while core cases 20 downside, at the point where those align to stator cylinder 17, are located at the same level with the rings of stator cylinder 17 made of ferromagnetic material 18.

The functional principle of the submersible pumps shall tackle the reciprocating travel of the plunger inside the thick- walled cylinder, wherein the required shifts of the fluid flow shall be effected using the suction (fixed) valve and the discharge (moving) valve. The plunger shall be driven to motion from the surface using the special rods.

The plunger cylinder pair being part of the proposed submersible pumping unit shall be made as the linear motor wherein the plunger shall be simultaneously the rotor and the cylinder, inside which the plunger moves, shall be made as the fixed stator.

The movement of the submersible pumping unit shall be effected using the frequency converter with the microprocessor- based control which may be located either on a surface or may be integrated into the pumping unit as a stand-alone module. The position of the rotor regarding the stator shall be defined by the magnetic-field sensors located inside the stator (absent on fig.). The submersible pumping unit shall operate as follows:

When switching for the first time, the microprocessor control unit shall put on the mode of searching for rotor 5 position via the magnetic-field sensors. When rotor 5 position is defined, the operating mode is on tackling the transfer of the required current frequency, phase and magnitude to corresponding coils 9. Induction coils 9 of stator 6 shall be connected to the three-phase alternating currentnetwork; the magnetic fieldemerges. Such magnetic field crosses the conductors of rotor winding 5 and induces EMFtherein, under the impact of which the currents will start flowing through the winding. The interaction of the currents with the magnetic field shall result in emergence of the power impacting towards the magnetic field shift. As impacted by such, rotor 5 shall start moving.

Motor control is fully identical with the control of the standard motor with the permanent magnets using the frequency converter. Wherein all parameters shall be control that are required for the normal operation of the motor (current, voltage, frequency, temperature and etc.).

The device shall be assembled as follows:

1. Stator 6 shall be made of three parts. Induction coils 9, the electrical outputs (winding 25) of which through special clearances 24 in core cases 20 will connect in a star similarly to the standard electric motors, shall be enclosed to steel core cases 20.

2. The the star of induction coils 20 shall be put onto stator cylinder 17 comprising the pressurised together (fused) heterogeneous rings made of the ferromagnetic 18 and the nonmagnetic 19 materials. The width of the rings made of the ferromagnetic 18 material is equal to the width of core cases 20 for induction coils 9, i.e. this is the continuation of core case 20 for coil 9; thus makes the value of the air clearance between stator 6 and rotor 5 equal to the minimum value being approximately one point tenth of a millimetre.

3. Rotor 5 is assembled from metal tube 1 1 and magnets 12 which are put in pairs onto metal tube 1 1 so that the magnet poles of each magnet pair 12 are directed counter-currently towards each other, forming the linear sequence of the north and south poles.

4. Then rotor 5 shall be inserted to stator 6.

The essence of the proposed subordinate module for the pumping unit shall be as follows:

The submersible pumping unit comprises the housing which is the steel tube, the suction valve, the protective filter, the cylinder stator, the plunger rotor with the discharge valve. The housing shall have the cable input to feed the pumping unit and shall be connected with the tubing string. The plunger cylinder pair shall be made as the linear motor. The plunger shall be simultaneously the rotor, while the cylinder, inside which the plunger moves, shall be made as the fixed stator.

The cylinder stator shall comprise the ring-type steel cores, to which the circular windings shall be inserted with the electrical outputs through the special clearances in the cores being connected between each other in a star; the thick-walled cylinder where the cores and the windings are located, while the cylinder is made of the pressurised together heterogeneous materials looking as a layer-cake in the longitudinal cross section; one material is ferromagnetic and the other is non-ferromagnetic; wherein the width of the ferromagnetic layer is exactly equal to the width of the steel cores, that is the ferromagnetic layer is the continuation of the winding core thus making the value of the air clearance between the stator and the rotor equal to the minimum value being approximately one point tenth of a millimetre. The circular windings and the cores shall be designed so that there are the cut-through holes (3 pes.) located axially along the total length of the stator where the heat pipes are inserted, on the upper end of which there is a radiator located in the flow of the drained fluid thus providing for the efficient heat evacuation from the stator.

The rotor shall consist of the circular permanent magnets with the metal inserts between those. The magnets shall be assembled in pairs so that the magnet poles thereof are directed counter-currently towards each other to form the linear sequence of the north and south poles. The width of the metal inserts between the magnets shall be equal to the width of the winding core, while the distance between the centres of the analogous poles shall be exactly equal to the triple width of the core with the winding. The rotor shall be assembled on the non-magnetic tube. The upper side thereof may be protected by a pipe designed as per the cylinder technology. The functionalities of the motor and the pump shall be combined within the single element which is the linear rotor. It shall be simultaneously the plunger of the pumping unit. Meanwhile the pump cylinder shall be simultaneously the motor stator to decrease the line dimensions of the pump unit by twice.

So far as the submersible pumping unit operated at large depths with the high ambient pressure (up to 200-300 kg per square centimetre), there is a need for the secure insulation of the electromagnetic system against the penetration of the surrounding fluid inside the motor. It is suggested creating almost the no- clearance system at the interaction between the rotor and the stator by using the insulating tube that consists of the alternating heterogeneous ferromagnetic and non-ferromagnetic rings. To insulate the rotor magnets, the same tube design may be applied. Wherein the magnetic flow in the stator-rotor magnet system shall be limited only by the properties of the material, to specify, by the values of the magnetic flux density. Putting it differently, to create the required stator-rotor magnetic flow, the significantly lower current shall be supplied to the induction windings to decrease the heating thereof which consequently allows decreasing the linear dimensions of the pumping unit or increasing the capacity per the length unit.

The proposed design shall have the following advantages as compared to the prototype:

1. Increasing the heat removal capacity

2. Economic efficiency 3. Decreasing the dimension provided the similar capacity

4. Increasing the capacity provided the similar dimensions

5. Maximum insulation against the environmental impact.

In such a manner, the set purpose of creating a submersible pumping unit while ensuring the intensive heat discharge and the stable capacity at lowering the dimension of the device has been fulfilled.

Industrial applicability

The submersible pumping unit is designed for integration into the submersible assembly of the oil production unit that consists of the ground-level assembly, the submersible assembly and the power cable between those.

The purpose of the ground-level assembly:

The ground-level assembly shall be designed to feed the submersible assembly, to adjust the settings and the operation modes thereof, to receive the telemetric information from the submersible assembly, to provide the communication with the external automated control system as well as to manage and visualise the technological processes.

The purpose of the submersible assembly:

The submersible assembly shall be designed to pump oil from the layer via the tubing string (TS), to measure the operation parameters of the pumping unit and the well, to transfer the telemetric and technological information to the ground-level assembly as well as to receive and execute the commands from the ground-level assembly.

The purpose of the power cable:

The power cable shall be designed to feed the submersible assembly as well as to transfer data between the ground- level assembly and the submersible assembly.

The aforesaid shall speak of the industrial applicability of the claimed invention.