RU2347879C1 - Turbodrill - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas well drilling equipment and namely turbodrills used as a drive for a rock destruction tool. The turbodrill includes housing (1) with turbine stators (3) mounted in series therein, a shaft with turbine rotors (4) installed in series on its top, radial bearings (5), as well as a support (7) and channels installed at the bottom of shaft (2) with an internal cylindrical cavity (d) where the channels provide hydraulic connection between turbine outlet chamber (g) and internal cylindrical cavity (d) of the shaft and are placed in groups located in various cross sections of the shaft.

EFFECT: improved reliability of the turbodrill when used in drilling intervals at increased rates of penetration and with large amounts of sand in flushing fluid.

5 cl, 4 dwg

Description

The invention relates to technical means for drilling oil and gas wells, and in particular to turbodrills for driving a rock cutting tool.

Sectional turbodrill is known (Gusman MT, Lyubimov B.G., Nikitin G.M., Sobkina I.V., Shumilov V.P. Calculation, design and operation of turbodrills. M: Nedra, 1976, p.52 Fig. 22), consisting of one or more turbine sections and a spindle section. The turbine section contains a housing and a shaft with sequentially installed stators and rotors of the turbine. The spindle section comprises a housing and a shaft with axial support. The shaft of the spindle section along the entire length has a cylindrical internal cavity.

The turbine stators are fixed in the turbine section housing, and the rotors on the shaft. The turbine shaft of the section is centered inside the housing by radial bearings, in the lower part of the turbine shaft a coupling half is fixed, which serves to connect to the shaft of the spindle section. Parts mounted on a turbine shaft are secured with a nut.

An axial support is installed in the spindle section, consisting of 15-20 rows of rubber-metal thrust bearings. The shaft is centered in the housing of the spindle section by radial bearings, and in the lower part by a nipple. The upper part of the shaft of the spindle section is equipped with a coupling half used to connect to the turbine shaft. In the housing of the coupling half of the shaft of the spindle section, channels are made that provide hydraulic communication between the turbine output chamber and the cavity of the shaft of the spindle section. The design of the coupling halves of the turbine and spindle sections provide the transmission of axial forces and torques from the turbine shaft to the shaft of the spindle section.

The possibilities of using a sectional turbo-drill at drilling intervals with a set of well curvature are limited due to the fact that a sectional turbo-drill consists of at least two sections, its length does not fit into a given well curvature.

A well-known single-section turbodrill (Drilling complexes. Modern technologies and equipment. / Edited by A.M. Gusman and KPPorozhsky. Yekaterinburg: UGGGA, 2002. P.154, Fig. 11.2), which is the closest in technical solution to the proposed invention and adopted as a prototype.

The specified turbodrill contains a housing and a shaft. About 100 turbine stages are sequentially installed in the turbodrill, with turbine stators fixed to the casing and turbine rotors on the shaft. The shaft is mounted inside the housing and centered on the radial bearings. An inner cylindrical cavity is made in the shaft under the axial support. For hydraulic communication of the output chamber of the turbine and the inner cylindrical cavity of the shaft, channels located in one cross section of the shaft are milled into the shaft. The lower part of the shaft is centered using a rubber nipple that acts as a radial bearing and shaft seal.

Known turbodrill has disadvantages that reduce the reliability of its operation. The execution of the channels in one group located in one cross section of the shaft limits the area of the passage channels of the hydraulic communication of the turbine output chamber and the cavity of the shaft, which leads to high flow rates of flushing fluid in the channels and accelerated wear of the channel walls. This design does not allow to reduce the flow rate of the washing liquid and to eliminate the wear of the walls of the channels.

The drilling speed of modern turbodrills can reach 200 m / h. Existing cleaning systems cannot cope with the volume of drilled particles, and the sand content reaches 20-30% even at lower drilling speeds. The flow of flushing fluid to the rock cutting tool for cleaning the face from cuttings occurs through channels that provide hydraulic communication between the turbine outlet chamber and the inner cylindrical cavity of the shaft. At the same time, due to the increased flow velocity and turbulence, the channels are intensively washed out. Not only is the erosion of the walls of the channels, but also the walls of the inner cylindrical cavity of the shaft, in the area opposite each channel. Such wear leads to premature failure of the turbo-drill shaft due to loss of its strength due to a decrease in the bearing section in the channel area. The implementation of the channels in one group located in one cross section of the shaft, does not make it possible to reduce the flow rate of the washing fluid and to eliminate the wear of the walls of the channels.

An object of the present invention is to provide a turbodrill with high reliability indicators for use at drilling intervals with increased penetration rates and a high sand content in the flushing fluid.

The problem is solved due to the fact that in the known turbodrill, comprising a housing with successively mounted turbine stators, a shaft, in the upper part of which turbine rotors, radial bearings are sequentially mounted, and in the lower part of the shaft, in which the internal cylindrical cavity is made, is installed the support, and channels are made providing hydraulic communication of the turbine outlet chamber and the inner cylindrical cavity of the shaft, according to the invention, these channels are arranged in groups arranged in different transverse directions cross sections of the shaft.

In addition, in the turbodrill according to the invention, the groups of channels are offset from each other along the axis of the shaft by a distance equal to or greater than the width of one channel, measured along the axis of the shaft.

In addition, in the turbodrill according to the invention, the channels of each group are rotated relative to an adjacent group of channels around the axis of the shaft.

In addition, in the turbodrill according to the invention, the angle of rotation of the channels of each group relative to each other is equal to half the angle measured between the channels within the group.

In addition, in the turbodrill according to the invention, the channels in each group are located opposite each other, so that the pressure of the hydraulic flows coming from the channels is balanced with each other.

The proposed design of the shaft of the turbodrill will provide a significant reduction in erosive wear of the internal cavity of the shaft when drilling the upper intervals of the wells, when the percentage of sand in the drilling fluid reaches a level of 15-25%.

The implementation of the channels in groups located in different cross sections of the shaft, can significantly reduce the flow rate of the drilling fluid by increasing the total area of the passage section of the channels and, thus, reduce erosion wear of the channels.

The offset of the groups of channels from each other along the axis of the shaft by a distance equal to or greater than the width of one channel, measured along the axis of the shaft, allows you to ensure the strength of the shaft by increasing the area of the bearing sections of the bridge jumpers located between the channels and forming the channel walls. In this case, the shaft jumpers have the necessary cross-sectional area to provide a margin of safety for transmitting torque to the bit. If the displacement distance of the channel groups from each other along the shaft axis is less than the width of one channel, then the cross-sectional areas of the shaft jumpers and their strength will be insufficient.

The channels of each group are rotated relative to the adjacent group of channels around the axis of the shaft, which allows for high torsional stiffness of the shaft with a smaller length.

Since the shaft jumpers located between the channels form a spatial frame loaded with a torque transmitted to the bit, in the case when the angle of rotation of the channels of each group relative to each other is equal to half the angle measured between the channels within the group, the shaft stiffness and shaft strength maximum torsion at its minimum length.

The channels in each group are located opposite each other, so that the pressure of the hydraulic flows emanating from the channels is balanced with each other. This arrangement of the channels makes it possible to balance the radial components of the vectors of hydraulic flows emanating from the channels and to virtually eliminate the direct pressure of the hydraulic jets on the walls of the inner cylindrical cavity of the shaft, which further reduces the erosive wear of the shaft.

The implementation of the turbodrill with the indicated features will allow for a minimum length of the turbodrill to obtain a highly efficient drive when drilling with a high penetration rate.

Figure 1 shows a General view of the performance of the turbodrill according to the invention.

Figure 2 shows a fragment H of a longitudinal section of a turbo-drill shaft made according to the invention.

Figures 3-4 show cross-sections A-A and B-B of a turbo-drill shaft made according to the invention.

The turbo-drill comprises a housing 1 and a turbine shaft 2. In the housing 1, stators 3 of the turbine are installed, turbine rotors 4 are installed on the turbine shaft 2. The turbine shaft 2 is centered in the housing 1 by radial bearings 5, and at the outlet of the housing 1 is centered by a nipple 6.

The axial support 7 is installed in the lower part of the shaft 2. The shaft 2 under the axial support 7 has an internal cavity d. For the passage of the drilling fluid in the shaft 2, channels a and b are made (Fig. 2), which provide hydraulic communication between the output chamber of the turbine g (Fig. 1) and the inner cylindrical cavity d (Fig. 2) of the shaft 2. Channels a and b are located in two groups . In each group, two channels are made: two channels a in section AA, and two channels b in section BB (FIG. 2). The implementation of the channels a and b in groups located in different cross sections of the shaft A-A and B-B allows to increase the total area of the passage section of the channels without loss of shaft strength. The place of the channels a and b is blocked by a spacer sleeve - a lantern 8, in which the channels e are made (Fig. 2), which coincide in the cross section with the channels a and b.

The parts mounted on the turbine shaft 2 are fixed due to axial compression by their nut 9 (Fig. 1). Parts installed in the housing are also fixed due to axial compression by a sub 10.

The turbodrill is connected to the drill pipes (not shown in FIG. 1) through an adapter 10. An adapter 11 connects the turbodrill shaft 2 with a bit (not shown in FIG. 1).

Turbodrill works as follows.

Using a sub 10, the turbodrill is connected to the drill pipes and lowered into the well. When the mud pumps are turned on, drilling fluid flows from drill pipes (not shown) into the turbodrill.

In a turbodrill, the drilling fluid first enters the first stator 3, then into the first rotor 4, and so on, passing through the stators 3 and rotors 4 of the turbine sequentially, drives the shaft 2. In total, 100-150 pairs of stators 3 and rotors 4 of the turbine are installed , the amount of which is determined from the condition of ensuring a given output characteristic of the turbodrill as applied to specific drilling conditions.

The last stator 3 and rotor 4 are located in the lower part of the turbine shaft 2, but above the axial support 7. Leaving the last rotor 4, the drilling fluid enters the turbine outlet chamber g above the sleeve 8, then into the channels e that are made in the sleeve 8, and further into the channels a and b of the shaft 2.

In figure 1, the channels a and b of the shaft 2 are located in two groups. Two channels were made in each group, two channels a in section AA, and two channels b in section BB. The execution of channels a and b by groups located in different cross sections of the shaft A-A and B-B allows to increase the total area of the passage section of the channels, reduce the flow rate of the drilling fluid and, thus, significantly reduce the erosive wear of the channels a, b and d.

The groups of channels a are offset from the group of channels b along the axis of the shaft by a distance greater than the width f of one channel, measured along the axis of the shaft 2. The offset of the groups of channels a and b allows for the strength of the shaft 2 by increasing the bearing cross-sectional area of the jumpers 12 of the shaft 2 located between channels a and b. In this case, the jumpers 12 of the shaft 2 located between the channels a or b have the necessary margin of safety for transmitting torque to the bit. If the distance of the displacement of the groups of channels a and b from each other along the shaft axis is less than the width of one channel f, then the strength of the jumpers may be insufficient.

The channels of group a located in section AA are rotated relative to the neighboring group of channels b located in section BB around the axis of the shaft 2, which makes it possible to increase the rigidity of the shaft 2 for torsion with a shorter length.

Since the shaft jumpers 12 located between the channels a and b form a spatial frame loaded with a torsional moment from the drill bit, then in the case when the angle of rotation of the channels of each group relative to each other is equal to half the angle β measured between the channels inside group a, the rigidity and strength of the shaft 2 torsion is maximum with a minimum length of it. The angle of rotation of the channels of each group relative to each other in figure 1 is equal to half the angle β, measured between the channels within the group a, and is 90 °.

The channels in each group are located opposite each other, so that the pressure of the hydraulic flows emanating from the channels is balanced with each other. Thus, the angle β between the channels is 180 °. The upper group (section AA) contains two channels a located opposite each other. The lower group (section BB) contains two channels b located opposite each other. Thus, the radial components of the vectors C of hydraulic flows emanating from the channels a and b are equal in magnitude and opposite in direction. Vector D shows the direction of motion of the flows C after they exit the channels a and b. Such an arrangement of the channels makes it possible to balance the radial components of the vectors C of the hydraulic flows emanating from the channels a and b and to practically eliminate the direct pressure of the jets directed to the walls of the inner cylindrical cavity of the shaft d, which further reduces the erosive wear of its walls.

When the turbodrill operates in the upper intervals of the wells, where the drilling fluid may contain a large amount of sand (up to 25%), the design of the turbodrill using the distinguishing features of the claimed invention reduces the erosion wear of the turbodrill parts and increases its reliability and durability.

After passing through the channels a and b, the drilling fluid enters the cylindrical cavity d of the shaft 2 and then into the bit, which destroys the rock at the bottom of the well. After the drilling process of the specified interval of the well is completed, the flow of drilling fluid into the turbodrill is stopped, and the turbodrill is raised to the surface, where its technical condition is checked and, if necessary, sent for repair.

Thus, the proposed technical solution allows to increase the reliability of the turbodrill when used at drilling intervals with increased penetration speeds and a high sand content in the flushing fluid.

Claims (5)

1. A turbo-drill, comprising a housing with turbine stators sequentially mounted in it, a shaft, in the upper part of which turbine rotors, radial bearings are sequentially mounted, and a support is installed in the lower part of the shaft equipped with an internal cylindrical cavity, and channels are provided that provide hydraulic connection of the output chamber the turbine and the inner cylindrical cavity of the shaft, characterized in that the channels providing hydraulic communication of the output chamber of the turbine and the inner cylindrical cavity of the shaft, made group and located in different cross sections of the shaft. 2. The turbodrill according to claim 1, characterized in that the groups of channels are offset from each other along the axis of the shaft by a distance equal to or greater than the width of one channel, measured along the axis of the shaft. 3. The turbodrill according to claim 1, characterized in that the channels of each group are rotated relative to the adjacent group of channels around the axis of the shaft. 4. Turbo-drill according to claim 3, characterized in that the angle of rotation of each group of channels relative to each other is equal to half the angle measured between the channels within the group. 5. The turbo-drill according to claim 1, characterized in that the channels in each group are located opposite each other so that the pressure of the hydraulic flows coming from the channels is balanced with each other.

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