IE52056B1 - Turbodrill - Google Patents

Description

The invention relates to turbodrills, particularly those designed for drilling deep oil and gas veils under complicated mining and geological conditions, or those designed for directional drilling in' applications where the well bote should be drilled with a minimum deviation from a pre-set path of drilling.

The invention provides a turbodrill comprising turbine sections, each having a casing and a hollow shaft, both made of a magnetic material, and a spindle installed in ' an independent casing and carrying a rock breaking tool, the turbodrill including a diamagnetic or paramagnetic pipe in which instruments are to be accommodated for measuring tbe position in space of a well bore being formed by the turbodrill, the. diamagnetic or paramagnetic pipe comprising two coaxial inner and outer pipes whose relative magnetic permeability is at most 1.12 and vhich are disposed between the spindle and an adjacent turbine section, tbe ends Of the outer pipe being rigidly coupled to the casing of the spindle and the casing of the said turbine section, and the ends of the inner pipe being coupled to the spindle and to the hollow shaft of the said turbine section so as to transmit rotary motion from the said hollow shaft to the spindle.

The design of the diamagnetic pipe, its position in the turbodrill and coupling to the turbodrill components make it possible to obtain most reliable information on the movement in space of the rock-breaking tool, such as a drill bit, and hence of the turbodrill and to promptly 520 56 ’ 3 control the turbodrill operation and movement of the drill bit with minimum deviations from a pre-set path.

The provision of the diamagnetic or paramagnetic pipe in the form of tvo coaxially arranged pipes makes it possible to separate tvo functions: transmission of an axial load to the drill bit and transmission of rotary motion to the drill bit, which have been heretofore performed by one and the same pipe, these functions being nov performed by two pipes. Ιθ The load is transmitted to the drill bit by the outer pipe since it is rigidly coupled to the drilling string, and rotary motion is transmitted to the drill bit by the inner pipe. This facility relieves the outer pipe from rotation so as to ensure its more accurate alignment with the well bore. Consequently, readings of the instruments housed in such diamagnetic or paramagnetic pipe give more exact indication of the three-dimensional position of a rock breaking tool (drill bit).

The arrangement of the tvo pipes between the spindle and the adjacent turbine section makes it possible to obtain more rational accommodation of instruments for measuring the three-dimensional position in space. Thus only a short spindle is between the measurement point and the drill bit so that the information on the movement of the drill bit in space may be obtained at a short distance from the drill bit and which is the most important, the position of the drill bit in space may be controlled by means of a short spindle.

It is most advantageous from the production point of view for the length of tbe pipes to be determined by the condition L«={30 to 60)D. wherein t is the length of the pipes and D is the outside diameter of the turbine section.

The length of the pipes determined by the above condition ensures the desired accuracy of measurement of the three-dimensional position in space, owing to the fact that the magnetic (i.e. ferromagnetic) masses of the turbine sections and spindle do not substantially affect the accuracy since they are separated from the instrument by the diamagnetic pipe over the above-mentioned length.

The rigid coupling of the outer pipe to the turbodrill components may be provided in the form of threaded ' joints between one end of the pipe and the spindle casing and between the other end of the same pipe and the casing of the turbine section. This rigid coupling ensures most simple arrangement from the manufacturing point -of view. s The coupling of the inner pipe to the turbodrill components may be provided in the form of threaded joints between one end of the pipe and the turbodrill spindle and between the other end of the same pipe and the hollow shaft of the turbine section.

The coupling of the inner pipe to the turbodrill components, may also comprise tapered splined couplings between one end of the pipe and the turbodrill spindle and between the other end of the same pipe and the hollow shaft of the turbine section.

This coupling makeJ it possible to obtain an arrangement facilitating assembly and disassembly and ensuring the transmission of rotary motion to the drill bit.

In order to provide for the possibility of flushing and maintenance of permanent cleanliness in the interior of the inner pipe to eliminate its clogging, for exact installation of the instrunents, the inner pipe is preferably couple/to the turbodrill components by means of a hydraulic coupling which is formed by the interior space of the turbine section communicating with the interior space of the spindle through the interior space of the inner pipe, and it is preferably to provide hydraulic seals at the end of the inner pipe and at the end of the hollow shaft of the turbine section and the end of the spindle corresponding to these ends.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a general view of a turbodrill in partial longitudinal section; Fig. 2 shows a threaded joint between the ends of an outer diamagnetic pipe and components of the turbodrill; Fig. 3 shows a threaded joint between the ends of an inner diamagnetic pipe and components of the turbodrill; Fig· 4 shows a tapered splined coupling of the ends of an inner diamagnetic pipe to components of the turbodrill.

The turbodrill shown in Fig. 1 comprises turbine sections 1 (only one of which is shown) and a spindle 2. Each turbine section 1 comprises a casing 3 attached to a drilling string 4 and a hollow shaft 5 having an interior space fi. Turbines of each turbine section 1 are arranged between the casing 3 and the shaft 5 and are formed by stators 7 secured in the casing 3 and rotors 8 installed on the hollow shaft 5. The hollow shaft 5 is aligned with the axis of the casing 3 by means of radial bearing 9 installed in the casing 3.

The spindle 2 is mounted in an independent casing 10 by means of a bearing 11 and carries a rock breaking tool in the 5 6 form of a drill bit 12. The bearing 11 aligns the spindle 2 with respect to the casing 10.

The turbodrill is provided with a diamagnetic pipe in which are housed instruments (not shown) for measuring the three-dimensional position of the well bore. The diamagnetic pipe consists of two coaxially arranged pipes - an outer pipe 13 and an inner pipe 14 - which arranged between the spindle 2 and the adjacent turbine section 1. The lower, end 15 of the outer pipe 13 is rigidly coupled to the casing 10 of the spindle 2 and the upper end 15 of the same pipe 13 is coupled to the casing 3 of the turbine section 1. The lower end 17 of the inner pipe 14 is coupled to the spindle 2 and the upper end 18 of the same pipe 14 is coupled to the hollow shaft 5 of the turbine section 1.

The rigid coupling of the ends 15 and 16 of the pipe 13 IS to the casing 10 of the spindle 2 and to the casing 3 of the turbine section 1 enables the transmission of an axial load from the drilling string 4 to the drill bit 12. The coupling of the ends 17 and 18 of the pipe 14 to the spindle 2 and to the hollow shaft 5 of the turbine section 1 enables the transmission of rotary motion from the hollow shafts 5 of the turbine sections to the spindle 2.

This arrangement of the diamagnetic pipe, its position and coupling to the adjacent components of the turbodrill enables reliable centering of the outer pipe 13, its rational position in proximity to the drill bit 12, and rigid coupling to the drilling string 4. This becomes possible owing to the fact that the inner pipe 14 transmits rotary motion to the drill bit 12 from the shaft 5 of the turbine section 1.

The pipes 13 and 14 are made of a diamagnetic material with a coefficient of magnetic permeability equal to or below 1.12 so as to ensure desired diamagnetic properties of the pipes. The length L of the pipes 13 and 14 is determined by the condition L=f30 to 60)D, wherein D is the outside diameter of the casing 3 of the turbine section 1. This length makes it possible to eliminate the effect of magnetic masses of the turbine section 1 and the spindle 2 on the accuracy of measurements for determining the three-dimensional position of the turbodrill in space.

The turbine sections 1 and the spindle 2 with the casing 10 may be of different diameters D depending on the diameter of the drill bit 12 employed; hence the magnetic mass thereof may also differ. The length L determined by its values from 30D to 600 covers the range of all practically used diameters of drill bits and turbine sections. ί ii It .»* j In order to align the outer pipes 13 in the well bore (not shown), ribs 19 and 20 are provided which are made in the fora of spirals embracing the pipe 13 over its periphery, the outside diameter Of the spirals being substantially equal to the outside' diameter of the drill bit 12. These ribs effectively align the pipe· 13 with.the well bore since they do not rotate, hence their wear rate is very small: A similar rib 21 is provided on the casing 10’of the spindle 2 and extends to a radius which is substantially equal to the outside radius of the drill bit 12 (its extentmay be greater than the outside radius of the drill bit 12.) This rib is designed for controlling the movement of the drill bit in space by acting on the drill bit 12 through the casing 10, bearing 11, and spindle 2.

The lower end 15 of the outer pipe 13 and the casing 10 . of the spindle 2 are coupled by means of a threaded joint 22 (Fig. 2), and the upper end 16 of the same pipe 13 is coupled to the casing 3 of the turbine section 1 by means of a threaded; joint 23. These threaded couplings provide for a .'rigid connection and transmission of load to the drill bit 12. The lower end 17 of the inner pipe 14 is coupled to the spindle 2 of the turbodrill by means of ..a threaded joint 24 (Fig. 3), and the upper end 18 of the inner pipe 14 is coupled to the hollow shaft 5 of the turbine section 1 by means cf a threaded joint 25. These threaded joints enable the transmission of rotary motion to 28 the drill bit 12 and simplify the desic’1 of the turbodrill. β '. · 5 · Fig. 4 shows another embodiment of the coupling of the inner pipe 14 to the components of the turbodrill, wherein the lower end 17 of the inner pipe 14 is coupled to the spindle 2 of the turbodrill by means of a tapered splined coupling 25, and the upper end 18 of the same pipe 14 is coupled to the hoi low shaft 5 of the turbine section 1 by means of a tapered splined coupling 27. This coupling enables the transmission of rotary motion to the drill bit without slippage and also accelerates assembly and disassembly of the turbodrill.

If an abrasive drilling fluid is used, the interior spaces 6 of the shafts 5 and the interior space 28 of the pipe 14 are flushed with a fraction of the abrasive fluid admitted to the turbodrill from the drilling string 4.

For that purpose, a flow nipple 29 (Fig. 1) is provided at the end 17 of the pipe 14 for controlling the flow of drilling fluid through the turbine sections 1. In order to reduce working pressure over the flow nipple 29, several flow nipples 29 may be provided having a greater inside diameter. This improves the reliability of turbodrill in operation and eliminates clogging of the nipple 29.

A hydraulic coupling of the drilling string 4 to the drill bit 12 comprises the interior space 6 of the shaft 5 of the turbine section 1, the interior space 28 of the inner pipe 14 and the interior space 30 (Fig. 4) of the spindle 2. To avoid leakage of drilling fluid from the interior spece 25 cf the inner pipe 14, there is a hydraulic seal 31 at the end 17 of theinner pipe 14 and at the end 33 of the hollow shaft 5, and also a hydraulic seal 32 at the end 34 of the spindle 2 and at the end 18 of the inner pipe 14.

To supply the main flow of drilling fluid to the drill bit 12, the drill bit is hydraulically coupled to the drilling string 4 through interior spaces 35 of the turbine sections 1, an interior space 36 of the outer pipe 13 and a port 37 in the periphery of the spindle 2 below the flow nipple 29, and the interior space 30 of the spindle 2.

Before lowering in the well bore, the turbodrill is assembled. The drill bit 12 is installed under the spindle 2. The pipe 13 is installed on the casing 10 of the spindle 2 with its end 15 by means of the threaded joint 22. The pipe 14 is then lowered into the pipe 13, the end 17 of the pipe 14 being coupled to the spindle 2. Subsequently, the casing 3 of the turbine section 1 is coupled to the end 16 of the pipe 13 by means of the threaded joint 23, the shaft 5 being coupled with its end 33 to the end 18 of the inner pipe 14.

The weight of the shaft 5 and pipe 14 is taken up by the bearing 11 through the spindle 2.

This method for assembling the components of the turbodrill is the most simple and convenient and enables the performance of various functions by these components.

Another method of assembly may also be used, wherein the inner pipe 14 is coupled to the components of the turbodrill by means of threaded joints 24 and 25. This method takes somewhat more time compared to the first one, but it ensures the sealing of the interior space 28, the importance of which will be explainet below.

The most convenient and preferable method of assembling the inner pipe 14 resides in coupling its ends 17 and 18 by means of tapered splined couplings 26 and 27 to the hollow shaft and spindle 2, respectively.

The interior space 28 is reliably sealed off by means of the seals 31 and 32 with respect to the adjacent interior space 36.

The turbodrill, assembled as described above, functions 15 in the well bore in the following manner.

Drilling fluid is supplied to the turbine section 1 through the drilling string 4 and is divided in the turbine section 1 into two flows.

The main flow of drilling fluid is admitted, through the interior space 35 of the turbine section 1, to the stators 7 and rotors 8.

After passing through all stators 7 and rotors 8 the main flow of drilling fluid is admitted to the drill bit 12 through the interior space 36 of the outer pipe 13 and the port 37 of the spindle 2.

The other flow of drilling fluid is admitted to the interior space 6 of the hollow shaft 5 of the turbine section 1 and to the interior space 30 of the -spindle 2, through the interior space 28 of the inner pipe 14 and the flow nipple 29, this flow merging with the main flow of drilling fluid in the interior of the spindle 2, to be admitted to the drill bit 12.

In order to avoid clogging of the interior space 28 of the pipe 14, it is continuously flushed during operation. The flushing is ensured by virtue of the sealing of the interior space 28 by means of the hydraulic restrictors or seals 31 and 32 so that no dead zones are formed in the interior space 28.

The rotors 8 drive the hollow shaft 5, which rotates in radial bearings 9 of the casing 3. Rotary motion is transmitted from the hollow shaft 5 through the inner pipe 14 and spindle 2 to the drill bit 12. Load from the drilling string 4 is transmitted to the drill hit 12 through the casing 3 of the turbine section 1, outer pipe 13, spindle casing 10, thrust bearing 11, end spindle 2.

Rotary motion is transmitted from the hollow shaft 5 to the pipe 14 through its end 18, and rotary motion is transmitted from the pipe to the spindle 2 through the end 17 of the pipe 14.

The outer pipe 13 transmits the load from the casing 3 of the turbine section 1 to the casing 10 of the spindle 2 through its ends 15 and 16.

Since the pipes 13 and 14 are made of a diamagnetic material, instruments {not shown) installed therein may determine (measure) the three-dimensional position of the turbodrill and drill bit in space. For making such measurement, the supply of drilling fluid to the turbodrill is temporarily cut off and, without pulling the turbodrill to the surface, instruments for measuring the three-dimensional position of the drill bit in space are lowered on a wire rope through the drilling string 4. The instrumen get from the string 4 through the hollow shaft 5 into the pipe 14 where the measurements are taken. The instruments are then pulled out and the supply of drilling fluid starts anew.

Such measurements may be taken as frequently as necessary.

The instrument readings are used to determine the need to correct the drill bit movement anti the operation of the turbodrill, es well as the position of the rib 21 with respect to the magnetic pole of the Earth.

This arrangement of the turbodrill makes it possible to drill directional holes under complicated mining and geological conditions so as to bring the drill bit to a predetermined target In addition, the use of the turbodrill is advantageous in drilling straight holes under conditions tending to cause spontaneous deviation of the well bore.

Claims (7)

CLAIMS:

1. A turbodrill conprising turbine sections, each having a casing and a hollow shaft, both made of a magnetic material, and a spindle installed in an 5 independent casing and carrying a rock breaking tool, the turbodrill including a diamagnetic or paramagnetic pipe in which instruments are to be accommodated for measuring the position in space of a well bore being formed by the turbodrill, the diamagnetic or 10 paramagnetic pipe comprising two coaxial inner and outer pipes whose relative magnetic permeability is at most 1.12 and which are disposed between the spindle and an adjacent turbine section, the ends of the outer pipe being rigidly coupled to the casing of the spindle and 15 the casing of tbe said turbine section, and the ends of the inner pipe being coupled to the spindle and to the hollow shaft of the said turbine section so as to transmit rotary motion from the. said hollow shaft to the spindle. 20

2. A turbodrill as claimed in claim 1, in. whieh the length of the pipes is 30 to 60 times the outside diameter of the casing bf the said turbine section.

3. A turbodrill as claimed in claim 1 or 2, in which the rigid coupling of the outer pipe comprises threaded 25 joints between one end of tbe outer pipe and the casing of the spindle and between the other end of the same pipe and the casing of the said turbine section. ύ. A turbodrill as claimed in any of claims 1 to 3, in which the coupling of the inner pipe comprises threaded joints between one end of the inner pipe and the spindle and between the other end of the same pipe and the hollow shaft of the said turbine 5 section.

4. 5. A turbodrill as claimed in any of claims 1 to 3,in wnich the coupling of the inner pipe conprises tapered splined couplings between one end of the inner pipe and the spindle and between the other end of the same pipe and the hollow shaft of the said 10 turbine section.

5.

6. A turbodrill as claimed in any of claims 1 to 3, including a hydraulic coupling which is formed by the interior space of the shaft of the said turbine section communicating with the interior space of the spindle through the interior space of the inner pipe, 15 the ends of the inner pipe and the end of the hollow shaft of the said turbine section and the spindle having hydraulic seals, at least one flow nipple being provided between the inner pipe and the spindle, for regulating the flow of drilling fluid through the turbine sections. 20

7. A turbodrill substantially as described with reference to, and as shown in, the accompanying drawings.