EP0457925A1 - Working organ of helical-type down-hole drive for hole drilling - Google Patents

Abstract

A working organ of a helical-type down-hole drive consisting of either a rotor with external helical teeth or a stator with internal helical teeth. The working organ comprises separate sections (1) provided with successively arranged helical teeth (3) and interconnected by sleeves (2). Each sleeve (2) is provided with helical teeth (4) corresponding in pitch and direction to those of the helical teeth (3) of the sections (1) and equidistant from the latter in profile. This enables automatic orientation of the helical teeth sections of the working organ.

Description

Technical field

The invention relates to drilling technology and relates in particular to a working member of screw-type bottom-hole motors for producing oil and gas holes. Both the rotor and the stator, which have screw teeth, are normally operated together in the motor, and can generally be called the working pair of the motor, as the working organ of a downhole screw motor.

Underlying state of the art

There is already a working organ of a downhole screw motor in the form of a rotor or stator is known, the number of screw teeth of the rotor one and more and the stator two and more. In each working pair, the stator and rotor teeth differ in number from one another.

In the well-known borehole sole motors, the rotors are generally made entirely of metal, consist of a rolling stock with a full cross section, or are tubular. The stators are made of rubber and metal and have screw teeth on the inside on an elastomer coating, which is connected to a cylindrical recess of the metallic stator frame by vulcanization. The number of screw tooth divisions of the working pair is a little more than two in the known motors. The production of a large number of screw tooth divisions of the working couple encounters procedural problems, nevertheless it is necessary to increase their number due to the increase in the force moment on the output shaft, which influences the technical-economic indicators of the drilling work. In recent times there has been a trend towards increasing the division number of the working couple signed the production of the work organ from interconnected individual sections.

For example, a work organ with several divisions for a bottom-hole screw motor in the form of a rotor or stator is known (US, A, 39I2426). The rotor contains individual sections with outer screw teeth that are continuously arranged one behind the other and are rigidly connected to one another by welding. The stator also has individual sections with internal screw teeth and a device for connecting the sections to one another. The latter is designed as openings on one of the end faces of the adjacent sections and as pins on the other end face. At their ends, the end sections of the stator are clamped in the housing by means of screws.

In this constructive design of the devices for connecting the sections of the working member, however, a particularly precise orientation of the helical working surfaces of the rotor, the sections of which are connected to one another by welding, as well as mechanical processing of the weld seam at the connection point of the sections, which is particularly difficult can be realized with multi-speed rotors that have more than one tooth and a complicated shape of the cross section. When the stator is used as a working element, the reliability of the connection of the sections deteriorates because the moment of force is transmitted between the sections via the pins of limited diameter, which depends on the cross section of the motor and the tooth height of the stator. This disadvantage is particularly important for multi-speed stators, which are characterized by a higher force torque when the motor is operated.

It is also known from FR-PS, A, 2349729, a working element for a downhole sole screw motor for producing bores, for example for a rotor, which consists of individual sections with external screw teeth, which are arranged continuously one behind the other and connected to one another by means of a device for connection. The device for connecting the sections to one another has a rod on which individual rotor sections are continuously placed. Openings for receiving bolts are provided on the end faces of the rotor sections, by means of which the sections are connected to one another. Some of the rotor sections on the rod are attached to their end faces by means of screws. Thanks to this structural design of the rotor, rotor sections of different lengths can be arranged on the rod, the production of which is not technologically difficult. The length of each section varies between I5 and 30 cm.

The working element of the downhole screw motor as a stator, just like the rotor, contains individual sections which are continuously arranged one behind the other. Openings for receiving bolts are provided on the end faces of the stator sections, through which the sections are connected to one another, and the stator sections are fastened in the housing by means of screwing on the end faces.

In this working organ of the downhole screw motor, too, the sections are not connected to one another reliably enough because the moment of force between the sections of the working organ (the rotor or stator) is transmitted via the bolts, the number of which does not exceed that of the working organ teeth and the bolt diameters by Sizes of the rotor or stator cross-section and are limited by the tooth height.

The orientation of the screw surfaces of the sections to be connected requires such additional work to be carried out in order to ensure a very precise mutual arrangement of the openings for receiving the bolts and their arrangement relative to the seating surfaces of the sections provided on the rod of the rotor or the stator housing and their arrangement relative to the screw teeth of the rotor or stator in the plane of the end faces of the sections of each working element. Any deviations in the mutual arrangement of the elements mentioned result in poorer orientation accuracy or make the assembly of the rotor or stator impossible.

Disclosure of the invention

The invention has for its object to provide a working organ for a downhole screw motor for producing boreholes, the connecting elements for the connection of the sections of this working member are designed so that the sections are reliably connected to each other, higher moments of force are transmitted and the processes both in the manufacture of these sections, as well as in their connection to the work organ do not become more complicated.

This object is achieved in that, in the case of a working element of a downhole screw motor for producing boreholes, which contains tubular individual sections with screw teeth which are arranged one behind the other and are connected to one another by connecting elements, according to the invention each connecting element is designed as a mount which is rigid on the sections to be connected is attached and has screw teeth, the pitch and direction of which are equal to the pitch and direction of the screw teeth of the sections to be connected, and the screw tooth profile of the socket is equidistant from the screw tooth profile of the sections to be connected.

It is expedient for each socket to have a constant or variable wall thickness.

In that the sections of the work organ connecting sockets are provided with the screw teeth, the pitch and direction of which are the same as the screw teeth of the sections, and that the screw tooth profile of the sockets is equidistant from the tooth profile of the sections, the force moment developing is transmitted via the interacting tooth screw surfaces, which are along the outline whose cross and axial section are applied. A large area of contact of the cooperating screw surfaces of sections of the working member and the frames connecting them results in low specific loads at the connection points and consequently a high reliability of the connection is ensured.

The equidistance of the screw tooth profiles of sections of the working organ and the sockets, which have the same pitch and direction of their screw teeth, makes it possible to automatically and precisely orient the screw teeth of the sections during assembly and to ensure the continuity of their screw surfaces at the junctures of the sections.

By designing the connecting element in the form of a socket with the same wall thickness, the weight of the working element can be reduced and the work step for its manufacture can be facilitated.

If one or more versions of the working element with variable wall thickness, e.g. of the rotor, a connection element for connecting the rotor to a cardan shaft or a flexible shaft can be provided on the mount, with the aid of which the moment of force is transmitted from the rotor to the output shaft of the support element of the screw motor.

The sockets with a variable wall thickness, which are arranged for the connection of the sections along the length of a rotor serving as a working element, reliably ensure the transmission of the torque with a reduced wall thickness of this working element.

Brief description of the drawings

• Fig. I die Gesamtansicht eines als Arbeitsorgan dienenden Rotors eines Bohrlochsohlen-Schraubenmotors zum Herstellen von Bohrlöchern mit äusseren Schraubenzähnen, gemäss der Erfindung, ein Längsschnitt;
• Fig. 2 einen Schnitt nach der Linie II-II in Fig. I, in vergrössertem Masstab;
• Fig. 3 einen Schnitt nach der Linie III-III in Fig. I, in vergrössertem Masstab;
• Fig. 4 die Gesamtansicht eines als Arbeitsorgan dienenden Stators eines Bohrlochsohlen-Schraubenmotors zum Herstellen von Bohrlöchern mit inneren Schraubenzähnen, gemäss der Erfindung, ein Längsschnitt;
• Fig. 5 einen Schnitt nach der Linie V-V in Fig. 4, in vergrössertem Masstab;
• Fig. 6 dito, wie in Fig. I, mit einer Schicht, die auf die Aussenfläche des Arbeitsorganes aufgetragen ist, ein Längsschnitt;
• Fig. 7 einen Schnitt nach der Linie VII-VII in Fig. 6, in vergrössertem Masstab.

In the following, the invention is explained in more detail by means of a detailed description of its exemplary embodiments with reference to the accompanying drawings, in which:

• Figure I is the overall view of a rotor serving as a working organ of a bottom-hole screw motor for producing holes with outer screw teeth, according to the invention, a longitudinal section.
• Figure 2 is a section along the line II-II in Figure I, on an enlarged scale.
• 3 shows a section along the line III-III in FIG. I, on an enlarged scale;
• 4 shows the overall view of a stator serving as a working element of a bottom-hole screw motor for producing boreholes with internal screw teeth, according to the invention, a longitudinal section;
• 5 shows a section along the line VV in FIG. 4, on an enlarged scale;
• Fig. 6 ditto, as in Fig. I, with a layer applied to the outer surface of the working member, a longitudinal section;
• Fig. 7 is a section along the line VII-VII in Fig. 6, on an enlarged scale.

Preferred embodiments of the invention

The working organ of a downhole screw motor with external screw teeth such as e.g. a rotor, is composed of tubular individual sections I (FIG. I), which are arranged consecutively one behind the other and are connected to one another by means of connecting elements in the form of sockets 2.

The sections I of the working organ have the shape of a tubular profile envelope with a constant wall thickness, the outer surfaces being the active surfaces Serve screw teeth 3. Each socket 2 is accommodated in the interior of the sections to be connected by carding over the joints of these sections, and has outer screw teeth 4 which, according to the division t and the direction with the division t _I and the direction of the teeth 3 of the sections I of the working organ to match. Here, the profile of the teeth 4 of the sockets 2 is equidistant from the profile of the teeth 3 of the sections I to be connected. As a result, the teeth 4 of the sockets 2 lie close to the inner screw surfaces 5 (FIGS. 2, 3) of the teeth 3 of both adjacent sections I. To ensure a hermetic seal and the fact that the connection point cannot be dismantled, the sockets 2 are rigidly attached to the sections I to be connected by methods known per se, such as soldering, gluing, welding or the like.

The socket 2 is a hollow part with outer teeth 4 and - as shown in FIG. 2 - has a constant wall thickness a or a variable wall thickness b, b _I - as shown in FIG. 3 - the length of the socket 2 being is 8 to 20 times shorter than the length of the sections I to be joined.

If the version 2 has a variable wall thickness, it can be used not only for the connection of the sections to each other, but also for the connection of the working element (a rotor) with a cardan shaft or a flexible shaft, which is used for the transmission of the moment of force and the axial load from Rotor on the shaft of the support element of the downhole screw motor (the propshaft and the support element are not shown in figures) are used.

The connecting elements according to the invention, that is to say sockets, can be used for connecting the sections of the working element of the downhole screw motor for which a stator is used, as can be seen in FIGS. 4, 5.

In this case, the sections 7 of the work organ, which are arranged continuously one behind the other and are designed as a tubular profile sleeve with a constant wall thickness, connected to one another by means of sockets 8, which are arranged from the outside on the sections 7 to be connected at their abutment and have a constant thickness.

Each socket 8 has inner screw teeth 9 which, according to the division t₂ and direction with the division t₃ and direction of the inner teeth I0 of the sections 7 of the working organ.

Here, the profile of the inner screw teeth 9 of the sockets 8 is equidistant from the profile of the inner teeth 10 of the sections 7 of the working organ to be connected. As a result, the teeth 9 of the sockets 8 lie tightly against the outer screw surfaces II of the two adjacent sections 7 and are firmly attached to them in a manner known per se, as stated above.

The end sections of the end sections 7 of the stator serving as the working member are connected to a drill string and a support element (not shown in FIG. 4).

As a result of the fact that borehole bottom screw motors are operated under abrasive conditions of the drilling fluid, it makes sense to coat one of the elements of the working pair with an elastomer, a nitryl rubber or another known suitable material to improve the wear resistance.

6, 7 show an embodiment of a rotor serving as a work organ, the outer screw teeth I2 of which are provided with a coating I3 which is applied by methods known in the art. This rotor can be used in combination with the stator shown in FIG. 4. It is obvious here that the coating can be applied to the inner surface of the screw teeth of the stator, which in the present case together with the I rotor can be used.

The working organ of a downhole screw motor, which is composed of several tubular sections which are connected to one another by means of sockets, can be of any length.

When assembling the work organ, e.g. a rotor, the tubular sections I are united with the socket 2 on the screw tooth surfaces and rigidly attached to the socket 2 in a manner known per se in the art (for example by soldering, gluing, welding or the like), thus making it undemountable and hermetically sealed Connection is reached.

The working member assembled in this way is then used as a working pair in a bottom-hole screw motor, which is operated as follows.

When a flush is fed into the interior of the working pair, its rotor, which serves as the working organ and is composed of the sections I (FIG. I), is rotated under the action of the unbalanced fluid pressure forces, by using its external teeth 3 on the internal teeth I0 ( Fig. 4) of the combined and existing from section 7, serving as a working stator rolls. Here, the tubular working element, which consists of the individual sections connected by the sockets 2 and 8, behaves as a one-piece, monolithic construction.

The presence of the sockets 2 and 8 with the screw teeth 4 and 9, which have a very low mass compared to the mass of section I, does not increase the degree of vibration of the working organ and ensures its ability to work at higher loads. The moment of force generated at sections I of the rotor is transmitted to the output shaft of the support element of the downhole screw motor by means of an articulated connection or a flexible shaft (the support element of the motor and other assemblies and parts are not shown in the figures).

Accordingly, the inventive design of the working element of a downhole screw motor makes it possible to increase the number of division of the working couple thanks to the connection of the individual sections of the rotors or stators by means of the sockets of the construction according to the invention and to increase the moment of force on the output shaft.

The sockets enable one section to be oriented automatically relative to the other, to make the connection point hermetically sealed, to reduce specific loads in the device and the working couple and to improve the functionality. This also increases the bending resistance of the stator teeth. The consumption of scarce, corrosion-resistant steel is saved in the manufacture of the working element, thanks to the use of the tubular sections of the working element, which are connected to one another by means of the likewise hollow part, that is to say the mount, there is the possibility of reducing the rotor mass and thus for the reduction of the dynamics of transverse vibrations of the engine and the associated wear of the working organ.

Industrial applicability

The bottom-hole screw motor with the working element designed according to the invention is used when drilling oil and gas wells, both a rotor and a stator with screw teeth being suitable as the working element of the bottom hole screw motor.

Claims (3)

Working element of a downhole screw motor for producing boreholes, which contains tubular individual sections (I or 7) with screw teeth (3 or I0), which are arranged one behind the other and are connected to one another by connecting elements, characterized in that each connecting element as a socket (2 or . 8) which is rigidly fastened to the sections (I or 7) to be connected and has screw teeth (4 or 9), the pitch and direction of which correspond to the pitch and direction of the screw teeth (3 or I0) connecting sections (I or 7), and that the profile of the screw teeth (4 or 9) of the socket (2 or 8) the profile of the screw teeth (3 or I0) of the sections to be connected (I or 7) is equidistant. Work organ according to claim I, characterized in that each socket (2 or 8) has a constant wall thickness. Work organ according to claim I, characterized in that each socket (2 or 8) has a variable wall thickness.

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