RU2334340C1 - Drilling electric generator - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: drilling electric generator contains a stator, point of attachment, a rotor with one or several groups of permanent magnets, kinematically connected with the drive for the moving of the magnets, and the excitation windings corresponding to them. The drive for the moving of magnets is capable of reciprocative transportation and contains a power element from material with memory of the form. The power element can be executed in the form of bellows, from a material with memory of the form, established in an airtight cavity inside the stator to which are supplied wires from the excitation winding through the switchboard, to which is in turn connected the power supply and the accumulator of electric power. On the front part of the stator there is a ribbing. In a back part of the electric generator there is an electric socket connected by electricity cables with windings of excitation. Inside the point of attachment there are openings. The point of attachment is on the front part of the stator, or in the middle part of the stator, or at the back part of the stator.

EFFECT: increase in the power and resource with the reduction of its diametrical dimensions.

7 cl, 1 dwg

Description

The invention relates to electric machines. Specifically, the invention is intended for a power generator for supplying downhole equipment and a transmission device for a downhole telemetry system. An electric generator converts the energy of the flushing fluid into electrical energy, which is necessary for supplying downhole navigation and geophysical instruments during drilling and the transmitter of the electromagnetic communication channel. For the telemetry system to work at great depths, an increase in the power of the transmitting device to 1 kW or more is required. To get more power with the small dimensions of the generator is very problematic.

A known alternator for powering the telemetric system in the process of drilling small diameter wells, including a fixed internal stator with a collector and an external rotor mounted on the drive shaft, equipped with electromagnets (RF patent No. 2060383, MKP ЕВВ 47/022, 47/00, priority from 21.02 .92 g). The lubrication system is a cavity between the rotor and the stator, filled with lubricating fluid.

A self-contained turbine unit (electric generator) is also intended for supplying electric energy to the telemetry system, containing a hydraulic turbine driven by a wash fluid stream, an oil-filled stator filled with an epoxy compound, and a rotor of an alternating current generator with permanent magnets located on the same shaft with a hydraulic turbine ( Molchanov A.A., Siraev A.X. “Borehole autonomous systems with magnetic recording.” M., Nedra, 1979, pp. 102-103).

This generator consists of a stator located inside the unit and a six-pole annular magnetic rotor made from the outside. The rotor is also a casing for the working blades of a three-stage hydraulic turbine. In front of each stage of the working blades of the hydraulic turbine, in turn, there are three stages of guide vanes assembled on the outer casing, which increases the diameter of the device. To prevent the flushing fluid from entering the generator and the bearing units, sealing devices are installed, the internal cavity of the generator is filled with transformer oil.

Due to the fact that the generator operates in the temperature range from -40 to + 130 ° C, at drilling depths of up to 3500 m or more, and the oil volume changes with temperature, a pressure compensator and thermal expansion of the lubricating fluid (oil) are introduced. The compensator for pressure and thermal expansion of the lubricating fluid is made inside the inlet fairing of the generator. It consists of two thin profile plates, one of which is convex, and the other is concave. The compensator for pressure and thermal expansion of the lubricating fluid is designed to compensate for changes in the volume of oil in the oil-filled cavity of the generator under operating conditions with increasing temperature, as well as equalizing the pressure inside and outside the generator.

The disadvantages of this generator are:

- low reliability

- small resource

- large dimensions and mass of the device,

- the complexity of the design.

These shortcomings are caused, first of all, by the fact that a multistage turbine with guide vanes is used as a drive. The use of a hydraulic turbine with guide vanes as a drive places high demands on the quality of cleaning the washing liquid from fractions of drill cuttings and foreign objects, the ingress of which into the gap between the working and guide vanes of the hydraulic turbine can cause it to stop (jamming). The presence of guiding devices of a hydraulic turbine increases the diametrical dimension of the electric generator, which is undesirable when drilling wells of relatively small diameter.

The second design flaw is the complexity and unreliability of the pressure compensator and thermal expansion of the lubricating fluid. Due to the elasticity of the walls of the compensator, the pressure of the lubricating fluid is always less than the pressure of the environment. This can result in flushing fluid entering the generator’s lubrication system and in the wear of bearings, seals and other parts.

Also known generator according to US Pat. RF №2173925, the main feature of which can be considered a lubrication system. The lubrication system of this generator contains a filling device at its front end, a cavity between the external rotor and the stator, filled with lubricating fluid, and a pressure compensator and thermal expansion of the lubricating fluid located on the side of the generator mounting device, made in the form of a piston mounted with axial movement and seals mounted inside the piston with the possibility of axial movement with it.

The disadvantage of this device is the difficulty of filling the system with lubricating fluid and a low seal life.

Known downhole power generator telemetry systems according to St. RF for utility model No. 34638.

This electric generator contains a filling device in its front part, a cavity between the external rotor and the stator filled with a lubricating fluid, and a compensator for pressure and thermal expansion of the lubricating fluid located on the side of the generator mounting device, made in the form of a piston mounted inside the rotor with axial movement , and the seal, installed, in turn, inside the piston with the possibility of axial movement with it, the piston is made with the possibility of drainage lubricating the fluid in the fully tucked position to the gap between the rotor and the alternator mounting assembly.

The disadvantage of this lubrication system is that due to the combination of the functions of the compensator and the seal, their life is reduced.

Known generator for St. RF № 13123, which contains a rotor with a turbine, a stator, a mounting unit and a reservoir for the reserve supply of lubricating fluid, made in the form of a cup made in the front of the generator with a spring-loaded piston installed inside, and a refueling device. The generator and turbine are significantly distant from each other in the axial direction and are separated by a magnetic coupling, which increases the dimensions of the generator and reduces the reliability of the lubricant.

A known generator according to the patent of the Russian Federation for invention No. 2264537, a prototype comprising a housing with field windings, a mount, a rotor with a shaft, magnets and a turbine mounted through bearings in the housing, and a reservoir for a reserve supply of lubricating fluid in the form of a cup made in front generator with a spring-loaded piston installed inside and a refueling device, characterized in that at least one front bearing is mounted in a sleeve that is centered in the protruding part of the housing, closed on the other side axis fixed from rotation and having an annular groove under the winding and a cylindrical protrusion, in the inner bore of which at least one rear bearing is installed, and a through axial hole is made inside the shaft. An adjustment washer is installed between the front bearing and the rotor. Field windings are installed in the housing and are fixed with pins against bias. The spring is partially placed inside the piston. The filling device is made in the form of a valve installed in the stem channel, closed by a plug.

Disadvantages: low power and resource of the generator with limited diametrical dimensions.

The creation of a powerful electric generator is limited by its diametric dimensions, and the low resource is explained by the fact that for the lubrication of numerous bearings (bearings), the internal cavity of the electric generator is filled with lubricating fluid, but due to the fact that during operation the drilling fluid containing abrasive particles, bearings gets inside the electric generator Seals and other parts wear out quickly.

The objective of the invention is to increase the power and resource of the generator while reducing its diametrical dimensions.

The solution to this problem was achieved due to the fact that the downhole electric generator containing a stator, an attachment unit, a rotor with one or more groups of permanent magnets, kinematically connected with a magnet displacement drive, and corresponding excitation windings, while the magnet displacement drive is configured to reciprocate translational movement and contains a power element made of a material with shape memory. The power element can be made in the form of a bellows made of a material with a shape memory installed in a sealed cavity inside the stator, to which wires from the field winding are connected through a switch, to which, in turn, a power source and an energy storage device are connected. On the front of the stator, ribbing is made. An electrical connector is made in the rear part of the generator (at its end), connected by electric wires to the field windings. Holes are made inside the mount. The attachment site can be made either in the front (downstream of the drilling fluid) part, or in the middle part, or in the back (lower, if the generator is installed vertically) of the stator.

The invention is illustrated in the drawing.

A downhole electric generator (see drawing), designed to supply downhole equipment, is installed in the drill pipe string or in the casing and contains a fastener 1 on the stator 2. In the fastener 1, holes “A” are made for the drilling fluid to pass to the downhole motor and rock cutting tool (not shown).

The downhole electric generator comprises a rotor 3 with one or more groups of permanent magnets 4 mounted on it.

A cavity “B” is made inside the stator 2, in which the magnet moving drive 5 is mounted. This drive can be of any design and must necessarily contain a power element 6 made of material with shape memory, one end of which is connected to the stator 2 and the other to the rotor 3. The drive moving the magnets 5 provides a reciprocating movement of the rotor 3 and the group of magnets 4 inside the field windings 7 installed in the cavity of the stator "B" concentrically to the groups of magnets 4. This is necessary to create the field windings 7 electric current. The power element 6 can be made in the form of a bellows of a material with shape memory, as shown in figure 1. Other forms of implementation of the power element 6 are possible, for example, in the form of a spring or a rod.

The cavity "B" is sealed and can be filled with a lubricating fluid or other solution to improve thermal conductivity and compensate for pressure and temperature expansion. This will eliminate the crushing of the thin wall of the stator 2. On the front of the stator 2 there is a fin 8 for removing heat.

The cavity "B" communicates with the cavity "C" in which the excitation windings 7 are located, and the baffle 9 is necessary for installing the guide sleeve 10. There is no pressure difference between the cavities "B" and "C".

From the excitation windings 7, the electric (s) wire (a) 11 leaves (it) 11, it passes through the holes "G" and "D" made in the stator 2, and are connected to the electrical connector 12. If one wire is used, then the function of the other the wires are performed by the stator 2. The connection of the field windings 7 can be made parallel, serial or parallel-serial. The electrical connector 12 can be output voltage from two groups of field windings 7 for power supply to various independent consumers. The electrical connector 12, it is advisable to perform coaxial.

The wires 13 connect the field windings 7 through the switch 14 with the power element 6 for periodic heating. A power supply 15, an electric energy storage 16, such as a battery, and a processor 17 for controlling the switch 14 according to a predetermined program are connected to the switch 14. The temperature of the drilling fluid in the well is usually in the range from 80 to 130 ° C. The temperature of the martensitic transformation of the power element can be adjusted, for example, to 150 ... 200 ° C. It is possible to use a temperature sensor 18 connected to the processor 17 in the system or a limit switch (limit switch) 19 under the rear (lower) end face of the rotor 3 (electrical connection between the limit switch 19 and the processor 17 is not shown.)

In order to actuate the downhole electric generator from the power source 15, a pulse of electricity is supplied to the power element 6 through the switch 14, which is sufficient for its heating by several tens of degrees, i.e. up to the martensitic transformation temperature. In this case, the power element 6 is extended and the rotor 3 moves back (down) by 10 ... 20 mm, depending on the thickness of the group of magnets 4. In this case, an alternating magnetic field is created inside the field windings 7, and an electric current is generated in the windings themselves. Subsequently, an electric current for heating the power element 6 is supplied through the switch from the energy store. The switch 14 is controlled by the processor 17, for example, by the temperature recorded by the temperature sensor 18.

The drilling fluid passing between the drill pipe and the fins 8 through the holes "A" cools the fluid with which the cavity "B" is filled, the power element 6 is cooled to the temperature of the drilling fluid, for example 80 ... 130 ° C, and the reverse martensitic transformation of the material with shape memory, the power element 6 reduces its length, and the rotor 3 moves forward (up).

These movements are carried out periodically, a group (groups) of permanent magnets 4 reciprocate inside the field windings 7. In the field windings 7 an electric current is generated, which is transmitted through electric wires 11 to electrical connector 12, and transmitted through electric wires 13 through switch 14 to the energy storage device 16.

The number of groups of permanent magnets 4 and field windings 7 can be made arbitrarily large. This will allow you to design a power source and downhole tools for drilling and casing strings of very small diameter.

The application of the invention allowed:

1. Significantly reduce the diametrical dimensions and weight of the downhole electric generator due to the abandonment of the hydraulic turbine.

2. To increase the power and voltage at the electrical terminals of the generator through the use of a large number of groups of permanent magnets and field windings.

3. To eliminate the imbalance of the rotor of the downhole electric generator due to the rejection of rotational motion.

4. Significantly increase the reliability of the generator due to the absolute tightness of its internal cavity and the absence of seals of rotating parts.

5. Simplify the design of the downhole electric generator, due to the rejection of the use of bearings and seals and simplify the design of all nodes and their unification.

6. To simplify the assembly and disassembly of the downhole electric generator due to its modular design and the use of a coaxial electrical connector.

7. Improve the maintainability of the downhole electric generator due to the extremely simple design, the minimum number of parts and the simple configuration of all parts.

Claims (7)

1. A downhole electric generator containing a stator with a mount, a rotor with one or more groups of permanent magnets connected with a magnet displacement drive, and corresponding stator field windings, characterized in that the magnet displacement drive is configured to create a reciprocating movement and contains a power element in the form of a bellows made of material with a shape memory installed in a sealed cavity inside the stator, one end of which is connected to the stator, and the other to the rotor and to the cat The wires from the stator field winding through the switch with a power source and an energy storage device connected to it were brought to the power supply. 2. The downhole electric generator according to claim 1, characterized in that on the front of the stator there is a ribbing. 3. The downhole generator according to claim 1 or 2, characterized in that in the rear of the generator there is an electric connector connected by electric wires to the field windings. 4. The downhole electric generator according to claim 1 or 2, characterized in that the holes are made inside the stator mount. 5. The downhole generator according to claim 1 or 2, characterized in that the stator mount is made in its front. 6. The downhole generator according to claim 1 or 2, characterized in that the stator mount is made in its middle part. 7. The downhole electric generator according to claim 1 or 2, characterized in that the stator mount is made in its rear part.