EP3271541B1 - Drill string element - Google Patents

Description

The invention relates to a drill string element for installation in a drill string for creating a borehole along a drill route, in particular for laying a pipeline, with a tubular base body with connecting elements on both sides for connecting the drill string element to the drill string, the drill string element having an interior through which a Flushing medium for flushing the borehole and the removal of cuttings loosened through a drill head connected to the drill string can be transported, with at least one opening connected to the interior in a wall of the base body, through which at least part of the flushing medium flowing through the interior into one Annulus between the borehole wall and the base body, wherein at least one body is arranged on the outer wall above the opening, in which at least partially a flow channel is arranged, the flow channel at least one flow channel g and is fluidly connected to the opening via an inlet opening, the flow channel on its side facing away from the opening at least one outlet opening, and the clear cross section of the opening and / or inlet opening being smaller or larger than the clear cross section of the outlet opening, wherein the outlet opening is arranged substantially axially to the central axis of the drill string element.

From the EP 0 360 321 A drilling and laying method (horizontal directional drilling) is known in which a pilot hole with a drill head and a drill string is made from a starting point to a target point for trenchless laying of a pipeline under an obstacle along a predetermined drilling line. The drill head is driven by turning the drill string. A scraper is then placed on the pilot drill string on the target side attached, which is connected to the pipeline to be laid. The reamer is driven by turning the drill string. The reamer is advanced while the pipeline is being pulled in by pulling out the pilot drill string.

When pilot drilling with the HDD process, the pilot drill head is pushed using boring bars and pushed along the planned route. A drilling suspension is pumped to the pilot drill head through an opening through the drill pipe. There, the cuttings mined by the pilot drilling head mix with the drilling suspension. This suspension then flows with the cuttings through the drilled borehole back to the starting point or entry point of the borehole. Since the diameter of the drill head is not significantly larger than the outside diameter of the boring bars, there is an annular space between the borehole and the boring bar. A flow forms in this annulus, with which the cuttings are conveyed out of the borehole.

Due to the shape of the flow channel in the annular space, there are zones in which the flow velocity is almost zero, in these zones carried cuttings are deposited, a so-called cuttings bed is formed. The consequence of these deposits is an increased torque of the rotating drill string due to friction against the cuttings on the bottom of the borehole. In addition, the free flow cross-section is reduced, the flow speed increases and thereby generates higher pressure losses during the backflow to the start of the bore. These pressure losses must be compensated for by the irrigation pump, which leads to an increased pressure level when the drilling suspension emerges from the pilot drilling head. The higher mud pressure at the outlet of the mud at the drill head can, depending on the rock or its nature, lead to the rock breaking up. The consequence of this is that undefined irrigation paths can usually arise perpendicular to the horizontal drilling axis directly to the surface, at which the drilling fluid then escapes in an uncontrolled manner.

In addition to the environmental aspect of an undefined irrigation outlet, drilling must also be interrupted because controlled removal of the cuttings is no longer possible. A so-called rinsing blow-out can only be done with great effort repair again by adding additives to the drilling fluid or cementing the blow-out point.

In practice, critical mud pressures are usually calculated in advance by superimposing existing geological data with a pressure calculation. The maximum values must not be exceeded. The pressure can be measured and monitored using pressure sensors behind the drill head.

EP 0171335 A1 discloses a drill string element for vertical drilling in the petroleum / natural gas sector. The drill string element has a flow channel with an inlet and a nozzle in the outlet, the nozzle being designed to be exchangeable. A fixed volume flow of flushing, which flows through the flow channel, is provided at the nozzle, which experiences a speed increase through the nozzle. A desired aggressive flushing jet is emitted vertically upwards, with the aim of providing movement in poorly / not flowed through zones of the bore above the outlet. The interchangeability of the nozzle is used for replacement when the degree of wear of the nozzle is reached for repair purposes. The body also acts as a stabilizer in the borehole to center the drill string with respect to the borehole walls.

US 2634101 A discloses a drill string element for vertical drilling in the petroleum / natural gas area directly behind the drill head. The drill string element has an element with a flow channel with an inlet and an outlet, the element being designed to be exchangeable. A fixed volume flow of flushing, which flows through the flow channel, is delivered at the outlet. A flushing jet is emitted vertically upwards behind the drill head. The interchangeability of the element is used for replacement when the element has reached a degree of wear for repair purposes.

WO 9604458 A1 discloses a drill string element for vertical drilling in the petroleum / natural gas area directly behind the drill head. The drill string element has an element with a flow channel with an inlet and an outlet. Flush that flows through the flow channel is released at the outlet when a certain purge pressure is inside of the drill string is exceeded by opening a valve. The release takes place radially horizontally towards the borehole wall. The clear cross sections are also the same.

US 20040011561 A1 also discloses a drill string element for vertical drilling in the petroleum / natural gas field. The drill string element serves, in the reverse arrangement, to receive flushing from the ring space into the drill string when flushing over the annular space and removing the cuttings over the drill string.

US 5407020 A discloses an apparatus and method for removing cuttings from vertical bores. The cuttings are removed pneumatically.

The object of the invention is to provide a drill string element and a drill string with the same, with which it becomes possible to keep the pressure in the annulus below the calculated limits or to keep the pressures prevailing in the annulus or drill string as low as possible. In the process, deposited cuttings should also be brought back into the flow or the cuttings should be prevented from settling.

The object of the invention is achieved in that the drill string is a drill string for horizontal directional drilling (HDD), that the drill route extends essentially horizontally from a starting point to a target point, that the clear cross section of the opening or the entry opening and the outlet opening is adjustable such that the setting is carried out by arranging at least one nozzle and / or orifice in at least two of the opening, the inlet opening, within the flow channel and / or in the outlet opening, the at least two nozzles and / or Orifices are designed to be exchangeable, and the nozzle and / or orifice plate is selected so that at the point of installation of the drill string element in the drill string in the borehole, the flushing medium can be dispensed into the annulus with a predetermined volume flow and / or pressure, the volume flow and / or pressure in the annulus depending on geological conditions it is set in the upcoming mountains, and that the at least one body extends on the base body, so that the outer radius of the base body increases in sections and there is an eccentric through which the drill string can be temporarily raised from the borehole wall during drilling.

The provision of two different clear cross-sections, in which the clear cross-section of the opening and / or inlet opening is smaller than the clear cross-section of the outlet opening, makes it possible in a particularly simple manner to provide a low pressure level at the nozzle outlet. This ensures a lower flow rate of the flushing medium at the outlet. This means that the flushing medium escapes less aggressively. With a high pressure level in the interior of the drill string and thus at the nozzle outlet, there is a risk that the drilling hole will be expanded by the flushing medium escaping. It has been shown so unexpectedly that it is possible in a particularly simple manner to introduce the escaping flushing medium gently into the annular space.

The provision of two different clear cross sections, in which the clear cross section of the opening and / or inlet opening is larger than the clear cross section of the outlet opening, makes it possible in a particularly simple manner to provide a higher pressure level at the nozzle outlet. This ensures a higher flow rate of the flushing medium at the outlet. As a result, the flushing medium escapes more aggressively. This can be used in particular when drilling cuttings are deliberately to be whirled up at the same time, the mountains in which the borehole is being made or the rock of the borehole wall is made in such a way that there is no danger at a high pressure level in the interior of the drill string and thus at the nozzle outlet that the borehole is expanded by the flushing medium escaping. Because the clear cross-section of the opening, the inlet opening and / or the outlet opening is adjustable, the desired parameters of the flushing medium can be adjusted / set particularly easily. The fact that at least one nozzle and / or diaphragm is arranged in the opening, the inlet opening, within the flow channel and / or in the outlet opening, preferably at least one nozzle and / or diaphragm being interchangeable, allows the desired ones Provide delivery parameters particularly easily. By changing the nozzle (s), the parameters desired at the operating point of the drill string element can be set particularly easily. As a result, different pressure levels within the drill pipe depending on the drill length are compensated for in a particularly simple manner. Furthermore, since the outlet opening is arranged essentially axially to the central axis of the drill string element, the flushing medium is dispensed along the drill string, which leads to movement of the cuttings, in particular if it has settled. Furthermore, widening of the borehole is avoided by direct action of the flushing medium that is emitted on the borehole wall. Characterized in that the at least one body, preferably the one body, extends on the base body, so that the outer radius of the base body increases in sections and there is an eccentric through which the drill string can be temporarily raised during drilling. The eccentrically designed drill string element causes the drill string to rise with every revolution. By lifting the flow cross-section in the upper area of the borehole is reduced, which leads to the drilling fluid flowing along the bottom of the borehole. As a result, deposited cuttings are returned to the drilling fluid.

Another teaching of the invention provides that the outlet opening is arranged in a rear side surface of the body. The outlet opening is advantageously arranged on the rear side surface in such a way that the drilling suspension exiting at the outlet opening, which has been taken up by a receiving and transport surface on the body and leaves it at the rear end, is carried along by the drilling suspension exiting there and thus the general flow fed back to the drilling suspension in the annulus and transported out of the borehole in the direction of flow.

A further teaching of the invention provides that a side surface is provided on the body, which is designed as a receiving and transport surface for drill cuttings deposited on a bottom of the borehole, the side surface preferably being helical in relation to the borehole axis. hereby the deposited cuttings are picked up and passed back to the drilling fluid.

A further teaching of the invention provides that an access opening is arranged in the body above the opening and / or the entry opening, in which preferably a blind flange is provided as the closure element. This makes it possible to change or adjust the nozzle / orifice in a particularly simple manner.

Furthermore, the object according to the invention is achieved by a drill string for creating a borehole along a drill line as an HDD bore with at least two of the drill string elements described above, in which the clear cross sections of the openings and / or inlet openings and the outlet openings are set relative to one another such that at the installation point in the drill string, the flushing medium is released into the annulus with a predetermined volume flow and / or pressure.

In addition, it should be said that the wording "and / or" is understood both as "and" and as "or" combination of the corresponding features.

The solutions of the invention are described in more detail below on the basis of a preferred exemplary embodiment in conjunction with a further drawing.

Fig. 1

eine erste räumliche Ansicht eines erfindungsgemäßen Bohrstrangelements,

Fig. 2

eine räumliche Seitenansicht zu Fig. 1,

Fig. 3

eine räumliche Ansicht der Unterseite zu Fig. 1,

Fig. 4

eine Ansicht zu Fig. 3 mit markierter Schnittansicht,

Fig. 5

eine Schnittansicht eines erfindungsgemäßen Bohrstrangelements gemäß Fig. 1, geschnitten wie in Fig. 4 angezeigt,

Fig. 6

eine räumliche Ansicht eines erfindungsgemäßen Bohrstrangelements in einem geschnitten dargestellten Bohrloch, und

Fig. 7

ein Diagramm der Druckverluste im Ringraum in Abhängigkeit zum Volumenstrom bzw. der Länge der Bohrung.

Show

Fig. 1

a first spatial view of a drill string element according to the invention,

Fig. 2

a spatial side view too Fig. 1 .

Fig. 3

a spatial view of the bottom too Fig. 1 .

Fig. 4

a view too Fig. 3 with marked sectional view,

Fig. 5

a sectional view of a drill string element according to the invention Fig. 1 , cut as in Fig. 4 displayed

Fig. 6

a spatial view of a drill string element according to the invention in a borehole shown in section, and

Fig. 7

a diagram of the pressure losses in the annulus depending on the volume flow or the length of the bore.

1 to 6 show an inventive drill string element 10 with a base body 11, which is tubular. The base body 11 has a male connecting element 13 at its front end 12 and a female connecting element 15 at its rear end 14, each of which is provided with a corresponding thread (not shown).

On the outer wall 16 of the base body 11, a body 17 is arranged, which is designed like a helix. In the preferred embodiment, the body 17 is welded onto the base body 11. However, it is also possible to arrange this on the base body 11 using other types of connection known to the person skilled in the art. The body 17 has a receiving and transport surface 19 on a side surface 18, with which, when the drill string rotates (direction of rotation A) and thus also during the rotation of the drill string element 10, which rests on a sole 101 of a borehole 100 in an annular space 102 between the outer wall 16 of the base body 11 and a borehole wall 103 drill cuttings (not shown) received by the receiving and transport surface 19 from the borehole bottom 101 and moved along the receiving and transport surface 19 during the rotation of the drill rod element 10 from the sole 101 until the drill cuttings on has arrived at the rear end 20 of the receiving and transport surface 19, at which the cuttings leave the receiving and transport surface 19 and are returned to the flowing drilling fluid in the direction of flow B in order to be transported out of the borehole 100 through the annular space 102. The cuttings are picked up at the tip 21 of the receiving and transport surface 19.

The base body 11 has an interior 22 as shown in FIG Fig. 5 is shown. Drilling fluid is transported through the interior 22 from the pump (not shown) to the drill head (not shown) against the flow direction B. The drilling suspension emerges at the drill head and picks up the cuttings loosened from the drill head and transports them through the annular space 102 in the direction of flow B or out of the borehole 100. In order to be able to specifically increase the volume flow in the annular space 102, an opening 23 is provided in the base body 11 , which opens into a flow channel 24. The flow channel 24 has an inlet opening 25 which is aligned with the opening 23. Alternatively, there is the possibility that the inlet opening 25 and the opening 23 have different clear cross sections. A nozzle 26 is provided in the opening 23 and defines the clear cross section of the opening 23 or in this case the inlet opening 25.

The flow channel 24 extends within the wall 27 of the base body 11 and / or in the body 17 to an outlet opening 28. A nozzle 29 is also arranged in the outlet opening 28 and defines the clear cross section of the outlet opening 28. Alternatively, orifices can also be provided instead of the nozzles.

The outlet opening 28 is arranged in a rear side surface 30 of the body 17. The arrangement is provided axially to the center of the borehole. An incidence in the radial direction is also possible, for example if the borehole wall is not released by the jet of the drilling suspension.

The inlet opening 25 or the flow channel 24 in the region of the inlet opening 25 extends up to the top 31 of the body 17 in order to provide access to the inlet opening 25 or opening 23, via which the nozzle 26 can be exchanged. A blind flange 33 is arranged in this access opening 32. This can be removed in order to be able to change the nozzle 26.

The outlet opening 28 with the nozzle 29 is arranged on the rear side surface 30 such that the drilling suspension exiting at the nozzle 29 removes the cuttings from the receiving and transport surface 19 was recorded and leaves it at the rear end 20, taken away by the drilling suspension emerging there and thus fed back to the general flow of the drilling suspension in the annular space 102 and is accordingly transported out of the borehole 100 in the direction of flow B.

If several drill string elements 10 are arranged in a drill string, it is possible to equip each / several of the drill string elements 10 with an individual nozzle set consisting of the nozzles 26 and 29, in order then to adapt the delivery of the drilling suspension in the borehole 100 to the individual installation locations.

By providing several drill string elements 10 in the drill string, the volume flow in the annular space is selectively increased. This is in Fig. 7 represented by the wave curve. This makes it possible to reduce the pressure losses in the annular space, which means that, overall, less volume flow has to be introduced into the annular space at the drill head, as a result of which the pressure losses decrease and the pump output can be reduced.

Starting from the drill head, the volume flow in the annular space 102 on each drill string element 10 is increased by the previously set volume flow. In the Fig. 7 The serrated curve shown is only for orientation to clarify the point at which a drill string element 10 was installed in the drill string. The pressure losses cannot be read from this curve.

In the in Fig. 7 In the illustrated example, 4 drill string elements 10 were used in the drill string with a total drilling length of 1,500 meters. The clear cross-sections / nozzles 26, 29 of the individual drill string elements 10 were selected / set in such a way that each drill string element 10 dispenses 200 liters per minute at the outlet openings 28. A volume flow of 1,000 liters per minute is present at the drill head itself. This results in a total volume flow of 1,800 liters per minute. Surprisingly, it has been shown that there is a pressure difference of 1.8 bar with a total drilling length of 1,500 m in accordance with the "total pressure loss" curve in the annular space. The unexpected reduction in almost 2 bar in the annulus significantly reduces the risk of getting a blowout. At the same time, wear is significantly reduced and energy costs are significantly reduced due to the reduced pump output.

LIST OF REFERENCE NUMBERS

10

drill string

11

body

12

front end

13

connecting element

14

rear end

15

connecting element

16

outer wall

17

body

18

side surface

19

Pick-up and transport area

20

rear end

21

top

22

inner space

23

opening

24

flow channel

25

inlet opening

26

jet

27

wall

28

outlet opening

29

jet

30

side surface

31

top

32

access opening

33

blind flange

100

well

101

sole

102

annulus

103

borehole wall

A

direction of rotation

B

Flow direction in the annulus

Claims (8)

1. Drill string element for installing in a drill string, for the creation of a drill hole (100) along a drill path, in particular for laying a pipeline, comprising a tubular main body (11) having bilateral connecting elements (13, 15) for connecting the drill string element (10) to the drill string, wherein the drill string element (10) has an interior (22) through which a flushing medium for the flushing of the drill hole (100) and the evacuation of drill cuttings loosened by a drill head connected to the drill string is transportable, comprising at least one opening (23), connected to the interior (22), in a wall (16) of the main body (11), through which at least a part of the flushing medium flowing through the interior makes its way into an annular space (102) between drill hole wall (103) and main body (11), wherein on the outer wall (16), over the opening (23), is arranged at least one body (17), in which is disposed, at least in part, a flow channel (24), in that the flow channel (24) has at least one flow path and is fluidically connected to the opening (23) via an inlet opening (25), in that the flow channel (24), on its side facing away from the opening (23), has at least one outlet opening (28), and in that the clear cross section of the opening (23) and/or inlet opening (25) is smaller or larger than the clear cross section of the outlet opening (28), wherein the outlet opening (28) is arranged substantially axially to the center axis of the drill string element (10), characterized in that the drill string is a drill string for horizontal directional drilling (HDD), in that the drill path extends substantially horizontally from a start point to a destination point, in that the clear cross section of the opening (23) or the inlet opening (25) and the outlet opening (28) is adjustable, in that the adjustment is carried out in that, in at least two of the opening (23), the inlet opening (25), within the flow channel (24), and/or in the outlet opening (28), is arranged in each case at least one nozzle (26, 29) and/or orifice plate, wherein the at least two nozzles (26, 29) and/or orifice plates are designed to be changeable, and in that the nozzle (26, 29) and/or orifice plate are/is selected such that, at the installation point of the drill string element (10) in the drill string in the drill hole, the flushing medium can be delivered into the annular space (102) with respectively predefined volumetric flow and/or pressure, wherein the volumetric flow and/or pressure in the annular space is fixed in dependence on the geological nature of the in-situ rock, and in that the at least one body (17) extends on the main body (11), so that the outside radius of the main body (11) is enlarged in some sections and an eccentric is present, by which the drill string can be periodically raised from the drill hole wall (103) in the course of the drilling.
2. Drill string element according to Claim 1, characterized in that the outlet opening (28) is arranged in a rear-end side face (30) of the body (17).
3. Drill string element according to Claim 1 or 2, characterized in that the at least one body (17) is constituted by precisely one body (17) or by two bodies.
4. Drill string element according to Claim 2, characterized in that the at least one body (17) is constituted by two bodies (17), lying one opposite the other.
5. Drill string element according to one of Claims 1 to 4, characterized in that on the body (17) is provided a side face (18), which is designed as a receiving and transport surface (19) for drill cuttings settled on a bottom (101) of the drill hole.
6. Drill string element according to Claim 5, characterized in that the side face (18) is designed helically in relation to the drill hole axis.
7. Drill string element according to one of Claims 1 to 6, characterized in that in the body (17), above the opening (23) and/or the inlet opening, is arranged an access opening (32), in which preferredly a blind flange (33) is provided as the closure element.
8. Drill string for the creation of a drill hole along a drill path as an HDD drilling, comprising at least two drill string elements (10) according to one of Claims 1 to 7, in which the clear cross sections of the openings (23) and/or inlet openings (25) and of the outlet openings (28) are set in such a way in relation to one another that at the installation point in the drill string the flushing medium is delivered into the annular space (102) with respectively predefined volumetric flow and/or pressure.

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