RU2295023C1 - Turbine screw downhole motor - Google Patents

Abstract

FIELD: well drilling equipment, particularly downhole motors.

SUBSTANCE: turbine screw downhole motor comprises gyrator mechanism, which acts in three dimensions, turbodrill and collar connected to turbodrill body and provided with elastic lining. The lining is connected to inner surface thereof and adapted to receive gyrator mechanism. Stator of gyrator mechanism is connected to shaft of turbine turbodrill section by means of tapered splined joint. The tapered splined joint comprises coupling and half-coupling and is connected to shaft of turbine turbodrill section. Rotor cooperating with stator is connected to upper motor sub through flexible member.

EFFECT: increased drilling efficiency, reliability and service life.

4 dwg

Description

The invention relates to downhole motors for drilling wells.

The downhole motors of the hydrodynamic and volumetric principle of action are known, for example, turbodrills and screw downhole motors, as well as turboprop engines made on the basis of aggregation of turbine and gerotor (screw) working bodies.

One of the first technical solutions of a turboprop engine was proposed in 1975 according to AC No. 557172, Е 21 В 3/12, in which a screw pair acts as a braking device, reducing the moment of force developed by the turbine by the amount of hydromechanical losses in the “rotor-stator” gear mesh section and, therefore, the speed of the output shaft of the engine. In such an engine, lateral vibrations and axial force from the rotor of the screw pair are transmitted through the flexible element to the shaft of the turbine section, reducing the reliability of the turbine and the axial support of the spindle.

Another modification of the turboprop engine is a technical solution for AC No. 1601307 A1, E 21 V 4/02.

This turboprop engine has a modular design and consists of a spindle, a turbine section and a screw working pair, in which the turbine rotor blades and the teeth of the screw rotor have an inclination of one direction to the axis of rotation.

When the working fluid is supplied from the pumps, the engine initially at low loads on the bit operates in acceleration mode. In this case, the screw pair operates in the pump mode, resisting the power turbine. This is because the rotor of a screw pair rotates by a turbine with a frequency greater than it would rotate at idle at a given flow rate of the working fluid without a turbine, and the screw pair ceases to function as a volumetric hydraulic machine (engine). As the load on the bit increases, the screw pair switches to the motor mode of operation, creating an additional moment of force on the output shaft of the engine with a corresponding pressure drop.

A significant drawback of this engine is that during its operation the main power element becomes a screw pair, which for this reason has less operating time than the turbine section. If the engine fails, the drilling process stops, while the rock cutting tool in most cases does not work out before the weapons wear out. In addition, a helical pair, generating transverse vibrations, negatively affects the performance of the turbine section and rock cutting tool.

A technical solution is known for a screw gerotor engine with a turbine activator according to AC No. 2203380 C1, E 21 V 4/02, F 03 B 13/01, the essence of which is to create a multi-start screw motor containing a screw gerotor pair in combination with a set of stator and rotor stages pressure of the turbine-activator, made with a special profile of the blades. The gaps between the rims of the rotors and stators in each stage of the turbine are closed by ring rubber-metal seals.

The rotors of the activator turbine are fixedly mounted on the shaft of the working section together with the rotor of the screw gerotor pair, and the stators of the turbine-activator are fixed in the housing of the working section together with the stator of the screw gerotor pair.

The screw gerotor pair due to the choice of a large angle of elevation of the helix from 30 ° to 60 ° has a multi-step design on a limited length and does not start well. Multiple helical pairs with a helix elevation angle of more than 30 ° during operation are started only with the rotor turning an additional (external) torque due to the large friction forces in the gearing.

The main disadvantage of a turbocharged screw gerotor engine is that, at the initial moment, a sufficient amount of hydraulic fluid must be pumped through a braked screw gerotor pair in order to create the required torque on the shaft of the activator turbine to start the screw pair. Pumping a working fluid saturated with sludge and sand through a locked screw gerotor pair can occur only during deformation of the stator teeth with the formation of slotted channels between the stator and rotor teeth, which will lead to catastrophic hydroabrasive wear of the rotor helical teeth and, especially, the stator.

When the engine enters the operating mode, the rotor system assembled and fixed on the shaft will oscillate-rotate with an amplitude of oscillations of the upper end of the motor shaft equal to two interaxal distances (eccentricities) of the internal gearing of the screw gerotor pair. During rotational-vibrational motion of the upper part of the shaft, which has a large mass, an unbalanced inertia force will arise, which, when the axial force, torsion and bending moments act on the shaft, will lead to complex eccentric loading of the shaft, the occurrence of alternating stresses in the shaft and its insufficient cyclic endurance. Transverse vibrations of the engine shaft will have a negative effect on the rock cutting tool, significantly reducing the reliability of the engine.

The technical task of the invention is to increase the efficiency of the drilling process, reliability and durability by increasing the torque on the output shaft to drive the rock cutting tool with a constant rotational speed in the range of applied axial loads on the rock cutting tool, reducing lateral vibrations and maintaining a turboprop operable state for a longer period downhole motor.

The task in a turboprop downhole motor including a volumetric gerotor mechanism and a turbo-drill is solved by the fact that according to the invention, the engine is equipped with a ferrule connected to the turbo-drill body, having an elastic lining on the inner surface, in which the gerotor mechanism is placed, and the stator of the gerotron mechanism by means of a cone-slotted the connection, consisting of a coupling and a half coupling, is connected to the shaft of the turbine section of the turbodrill, and the rotor interacting with the stator is connected by a flexible element to the top m engine sub.

Thus, the joint work of the turbo-drill and the screw gerotor mechanism with a rotating stator, which is connected by means of a cone-splined connection consisting of a coupling and a half-coupling, with the shaft of the turbine section of the turbo-drill will reduce the level of transverse vibrations in the area of the rotor-stator screw pair and stable operation of the rock cutting tool in optimal mode with a high moment of force on the output shaft of the engine.

Figure 1 shows a section of the working section, including the connection of the cage and the stator of the screw gerotor mechanism with the turbine section.

Figure 2 shows the connection of the turbine and spindle sections of a turboprop engine.

Figure 3 shows a cross section of the working section.

Figure 4 shows a variant of the connection of the working section with the turbine section.

The working section "a" of the engine, the section of which is shown in Fig. 1, includes a stator 1 and a rotor 2 of the gerotor mechanism, a ferrule 3, a coupling 4, a flexible element 5 made in the form of a torsion bar, an upper sub 6 and a plunger 7.

The turbine section "b", shown in figures 1 and 2, consists of rotors 9 and stators 10 of a multi-stage turbine mounted on the shaft 8, heel disks 11, thrust bearings 12, radial bearings 13 and the coupling half screwed onto the shaft 8. Details assembled on the shaft 8, are installed in the housing 15 until it stops in the connecting sub 16.

Figure 2 shows the connection node of the shafts 8 and 17 and the housing 15 and 18 of the turbine "b" and spindle "c" sections using the coupling 19, the coupling half 20, the sub 21 and 22.

Figure 1 shows a plunger 7 mounted in a cage 3, which when interacting with the housing of the stator 1 limits the flow of working fluid through the annular gap between the lining 23 of the cage 3 and the housing of the stator 1, as well as the movement of the stator 1 up.

The turboprop downhole motor shown in Fig. 1 and Fig. 2 is a universal engine that combines a high-performance turbo-drill and a high-torque gerotor screw mechanism with a rotating stator mounted in a cage, which made it possible to stabilize the output characteristic of the engine by the output shaft rotation frequency from idling until reaching the maximum power mode, thereby increasing the efficiency of the drilling process and the durability of the work.

The rotor-stator gerotor screw pair in a turboprop engine performs the function of a gear mechanism and combined in one unit with the turbine and spindle sections provides the optimum drilling mode for the required torque on the motor shaft.

The greatest efficiency of the drilling process, as well as higher reliability and durability of the turboprop downhole motor, is achieved by performing, when the idler speed characteristics of the gerotor mechanism are 1.1-1.3 times greater than the turbine section in maximum power mode.

In the working section "a", shown in figure 1, the gerotor mechanism with a stator 1 and a rotor 2 located therein is a helical gear pair with internal gearing with the right direction of the helical teeth line on both the stator 1 and the rotor 2.

A cross section of the section of the working bodies "a" is shown in figure 3. The stator is installed with a guaranteed gap in the cage 3, on the inner surface of which there is a lining 23 made of an elastic material, such as rubber. To lubricate the stator housing 1 with the working fluid during its rotation in the lining of the casing 3 in the lining 23, channels “d” are made. The annular gap formed between the rubbing surfaces of the stator housing 1 and the elastic lining 23 of the cage 3 has a large hydraulic resistance, which creates an obstacle to the flow of the working fluid. In the holder 3, a plunger 7 is installed, which, interacting with the upper end of the stator 1, restricts the movement of the stator 1 upward and, at the same time, blocks the flow of working fluid through the channels “d” of the lining 23 of the holder 3.

The holder 3 is connected to the housing 15 of the turbine section by a connecting sub 16. At the other end of the holder 3, an upper sub 6 is installed, having a jumper inside which has openings for the flow of working fluid. In the central part of the bridge of the sub 6 there is a thread into which the flexible element 5 is screwed. A rotor 2 is attached to the lower end of the flexible element 5.

The stator 1 is connected to the shaft 8 of the turbine section "b" by a coupling 4 and a coupling half 14 using threaded connections. In the coupling 4 channels “g” are made for the flow of the working fluid.

In the turbine section "b", shown in figure 1 and figure 2, a set of rotors 9 and stators 10 of a multi-stage turbine, radial bearings 13 and an auxiliary axial bearing consisting of heel disks 11, thrust bearings 12 and spacer rings are mounted on the shaft 8. The parts mounted on the shaft 8 are fixedly fixed by axial force due to compression of the package of parts on the shaft when the coupling half 14 is screwed onto the thread of the shaft 8.

A package of parts assembled on the shaft 8 is installed in the housing 15 of the turbine section “b” and secured against rotation by compressing the bearings 12 and stators 10 at the ends with axial force when screwing the adapters 16 and 22 into the housing 15.

When assembling the engine on the drilling site, the spindle section “c” is first attached to the turbine section “b” by screwing the threaded connection between the adapters 21 and 22, as well as by joining the coupling 19 and the coupling half 20 along the splines and cones. The working section "a" with a gerotor screw mechanism is sequentially connected to the turbine section "b" when screwing the cage 3 onto the connecting sub 16, while ensuring the coupling of the coupling 4 and the coupling half 14 through a conical-splined connection.

The connection of the working section "a" and the turbine section "b" can be performed according to the scheme shown in figure 4. An adapter 24 is screwed onto the shaft 8 of the turbine section “b” instead of the coupling half 14. The stator 1 is connected to the adapter 24 on the thread. When assembling the engine, the cage 3 of the working section “a” on the thread is connected to the connecting sub 16. The connection of the turbine section “b” with the gerotor the mechanism is carried out in stages. A stator 1 is screwed onto the adapter 24, onto which the yoke 3 is installed. The yoke 3 is screwed onto the connecting adapter 16. A plug 7 is installed in the yoke 3. A flexible element 5 is screwed into the rotor 2, and the second end is screwed into the jumper of the upper sub 6. The rotor 2 is installed in the stator 1, and when the assembly of the working section “a” is completed, the upper sub 6 is screwed into a ferrule 3.

A turboprop engine is lowered into the well on a drill pipe string, and when the pump unit feeds the working fluid through the pipes, the engine shaft is rotated.

The working fluid pumped through the rotor-stator screw pair creates a moment of force on the stator, which is transmitted to the shafts of the turbine and spindle sections. Further, the flow of the working fluid enters the turbine section and creates an additional moment of force in the multistage turbine. Since the flow of flushing fluid sequentially enters the working and turbine sections, their characteristics are summed up according to the developed moments of forces and pressure drops during braking loads on the motor shaft.

The proposed turboprop downhole motor allows it to be effectively used when drilling wells in connection with the possibility of realizing a large moment of force on the motor shaft to drive the rock cutting tool with a slight change in the output shaft speed in the range of applied axial loads on the bit.

In the engine, in which the rotor of the gerotor mechanism is fixed at the lower end of the flexible element, and the stator in absolute motion rotates coaxially and simultaneously with the shaft of the turbine section, only the rotor will be the generator of lateral vibrations in the running engine. The rotor suspended on a flexible element, having a small mass in comparison with the mass of the rotor system of a screw gerotor engine with a turbine activator, does not create significant centrifugal inertia forces when moving, causing transverse vibrations of the engine.

With a rigid connection of the stator of the gerotor mechanism with the shaft of the turbine section and the spindle by means of cone-splined joints, torsional vibrations of this system during engine operation are smoothed and do not adversely affect the operation of the bit. The efficiency of the drilling process and the durability of the rock cutting tool largely depend on the uniformity of rotation of the engine output shaft.

Stabilization of the angular velocity of the shaft of a turboprop engine leads to an increase in the mechanical drilling speed, an improvement in the quality of the wellbore wiring, and an increase in engine durability.

In the proposed turboprop downhole motor, consisting of a spindle and turbine sections, as well as a working section with a cage in which the stator of the gerotor mechanism is located, the working moment of force is transmitted from the rotating stator directly to the shaft of the turbine section and to the shaft of the spindle section without dynamic overloads. In existing turboprop engines, where the working section has a gerotor mechanism and the moment of force is transmitted to the shaft of the turbine section from the moving rotor using a connecting element, as well as in the engine, where on the shaft of the working section, simultaneously with the pressure stages of the activator turbine, is fixed the rotor, the rolling movement of the rotor along the teeth of the stator causes transverse vibrations of significant amplitude in these systems, leading to a decrease in the durability of the engines and a negative impact Suitable on the rock cutting tool.

Claims (1)

A turboprop downhole motor including a volumetric gerotor mechanism and a turbo-drill, characterized in that the engine is equipped with a ferrule connected to the turbo-drill body, having an elastic lining on the inner surface, in which the gerotor is placed, and the gerotor stator by means of a cone-splined connection consisting of a coupling and a coupling half, connected to the shaft of the turbine section of the turbodrill, and the rotor interacting with the stator is connected by a flexible element to the upper engine sub.

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