EP1564367B1 - Earth displacement drill - Google Patents

Abstract

Displacement drill comprises a drill pipe (10) running linearly up to the drill head (12), a mixing element (40) rigidly fixed to the outer periphery of the drill pipe, and radially protruding ribs arranged on the drill head. An independent claim is also included for a process for the production of a drill head using the displacement drill. Preferred Features: The mixing element does not radially protrude over the drill head and extends radially outward up to the largest radius of the drill head. The mixing element is arranged directly above the drill head.

Description

The present invention relates to a Erdverdrängungsbohrer according to the preamble of claim 1 (see, DE 195 30 718 G).

When using such a Erdverdrängungsbohrers this is driven under rotation into the ground, wherein due to the larger radius of the drill head between the resulting drill channel and the drill pipe creates an annular space. For drilling, a drilling fluid is usually introduced into the drill channel in the area of the drill head. Such a drilling fluid may for example be water, but often consists of a mixture of cement and mortar, although other additives can be used.

The lubricating action of drilling fluid mixed with constituents of the soil material allows the drill pipe to be drilled to a desired depth. After creating the drilling channel, it can be filled with concrete to form a pile.

Due to the ever increasing loads on such piles and the desire for settlement-free foundations, nowadays drilling channels have to be drilled deeper and deeper. Also, due to these requirements, the cross section of the drill pipe and the drill head is getting bigger. However, the desired pile depth can often not be achieved be because the drilling fluid disappears into a porous or coarse-grained soil layer or because the annulus, which has formed between the drill pipe and the drilling channel, is filled by burbling soil material, so that the lubricating effect of Bohrfluids deleted. As a result, the friction increases on the drill pipe and the torque required for further drilling becomes so great that the drilling process comes to a standstill, although the desired drilling depth has not yet been reached. A solution to this problem would be to increase the applied torque. However, in this case, the thickness of the drill pipe would have to be increased drastically, so that an economic use of such Erdverdrängungsbohrers is out of the question.

It is the object of the present invention to provide a soil displacement drill and a method for creating a well, with which it is possible to provide wells cost and with greater depth and / or larger diameter.

The solution of this object is achieved by the features of the independent claims.

By introducing drilling fluid into the area of the drill head and / or the annular space between the drill pipe and the wall of the drill channel, parts of soil material mix with the drilling fluid, wherein the mixing element provided according to the invention ensures that soil material and drilling fluid mix particularly well and intensively. As a result, friction is significantly reduced, so that on the one hand with larger Diameters can be drilled and on the other hand significantly greater drilling depths can be achieved.

Advantageous embodiments of the invention are described in the description, the drawings and the subclaims.

According to a first advantageous embodiment, the mixing element may be dimensioned such that it does not protrude radially beyond the drill head and in particular extends radially outward approximately to the largest radius of the drill head. In this way, it is ensured that the mixing element does not undesirably increase the drilling channel. By a radial extent to about the largest radius of the drill head ensures that a thorough mixing of drilling fluid and soil material over the entire cross section of the annulus takes place.

According to a further advantageous embodiment, the mixing element is arranged directly above the drill head. Such an embodiment is particularly advantageous when the drilling fluid exits through one or more openings in the region of the drill head in the wellbore. In this way, the mixing can be done immediately above the drill head.

According to a further advantageous embodiment, the mixing element is formed so that between this and the drill pipe, in particular a closed volume is included. In other words, the mixing element is designed as a body, whereby a particularly good mixing is achieved.

According to a further advantageous embodiment, the mixing element has at least one wedge surface, which forms a tapered region in cross section with the wall of a drilling channel formed by the drill head. In this particularly advantageous embodiment, the wedge surface ensures that upon rotation of the drill pipe, the mixture of drilling fluid and soil material is forced into the tapered region, wherein the mixture is then registered by the rotational movement of the wedge surface in the wall of the drilling channel. In this way, as it were a plastering of the drilling channel can be achieved by the mixed by the mixing element mixture of drilling fluid and soil material is pressed into the wall of the drilling channel. This provides a highly stable bore that does not break down and prevents drilling fluid from leaking into the surrounding soil.

According to a further advantageous embodiment, the mixing element may have a convex outer surface, which is in particular formed symmetrically. As a result, a particularly good introduction of the mixed material is achieved in the wall of the drilling channel. Particularly good results have resulted from the fact that at least one outer surface was provided on the mixing element, which was arranged approximately tangentially to the drill pipe.

The mixing element may in principle be arranged parallel to the drilling axis, but may also be arranged obliquely on the drill pipe, so that a plane passing through the center axis of the drill pipe forms an angle with the longitudinal axis of the mixing element.

The longitudinal extent of the mixing element can vary. Good results have been found when the mixing element is about one and a half to two and a half times the diameter of the drill pipe.

In a method of making a wellbore with a soil displacement drill of the type described in the present invention, the drill is drilled into the ground, introducing drilling fluid into the annulus formed between the wellbore and the wellbore, with the drilling fluid mixed above the wellhead. The introduction of the drilling fluid preferably takes place via the tip of the drill head so that it initially exits into the borehole formed by the drill head and then fills the annular space between the drill pipe and the borehole. By turning the drill pipe, the drilling fluid and the soil material above the drill head is mixed, whereby the advantages described above are achieved.

Fig. 1

einen Längsschnitt durch einen in einem Bohrkanal angeordneten Erdverdrängungsbohrer;

Fig. 2

einen Schnitt entlang der Linie II-II von Fig. 1;

Fig. 3a und 3b

eine dem Detail III von Fig. 2 entsprechende Schnittansicht zweier verschiedener Ausführungsformen; und

Fig. 4

eine Seitenansicht des Bohrkopfes von Fig. 1.

Hereinafter, the present invention will be described purely by way of example with reference to advantageous embodiments with reference to the accompanying drawings. Show it:

Fig. 1

a longitudinal section through an arranged in a drill hole Erdverdrängungsbohrer;

Fig. 2

a section along the line II-II of Fig. 1;

Fig. 3a and 3b

a detail III of Figure 2 corresponding sectional view of two different embodiments. and

Fig. 4

a side view of the drill head of Fig. 1st

The Erdverdrängungsbohrer shown in Fig. 1 has a circular cylindrical drill pipe 10, at the lower end of a drill head 12 is welded. The illustrated enlarged in Figure 4 drill head 12 has at its rear end an annular shank portion 14 into which the front end of the drill pipe 10 is inserted, whereupon drill pipe 10 and drill head 12 can be connected to each other by means of a welded joint 16.

The shaft portion 14 is adjoined by a cone-shaped tip portion 18, which is integrally formed with the shaft portion 14. Both in the region of the shaft portion 14 as well as the tip portion 18 a plurality of helical ribs 20, 21, 22 and 23 are provided, wherein the ribs 20 and 21 project radially from the shaft portion 14 and the ribs 22 and 23 protrude in the axial direction of the tip portion 18. Provided on all the ribs are spaced-apart teeth 24 which point in the axial direction of the drill head 12, which coincides with the drilling direction X (FIG. 1).

As shown in FIG. 1, the entire drill head 12 is integrally formed. The drill head 12 as well as the drill pipe 10 are made of steel.

1 further clarifies, the radius of the drill pipe 10 is smaller than the largest radius of the drill head 12, so that when inserting the Erdverdrängungsbohrers in soil material between the resulting drill channel and the drill pipe 10, an annular space 30 is formed. Fig. 1 also illustrates that both the resulting in the region of the drill head 12 wellbore 32 as well as the annular channel 30 are filled with a mixture of drilling fluid and particles of the soil material. The drilling fluid is guided through a pipe 34 disposed inside the drill pipe 10 in the region of the foremost end of the drill head 12 and occurs from there via radial outlet channels 36 into the borehole 32. The exiting drilling fluid 38 mixes with particles of the soil material and fills the wellbore 32 as well as the wellbore 30.

On the outer circumference of the drill pipe 10, a mixing element 40 is provided immediately above the drill head 12, which extends in the longitudinal direction X of the drill pipe and which does not project radially beyond the drill head 12, but extends radially outward approximately to the largest radius of the drill head 12. In the embodiment shown in FIGS. 1, 2 and 3a, the mixing element 40 is a groove-shaped component whose radius is smaller than that of the drill pipe 10. The mixing element 40 is welded in the illustrated embodiment to the outer shell of the drill pipe 10 and closed at its top and bottom, so that between the mixing element 40 and the drill pipe 10, a closed volume is included.

Fig. 3b shows another embodiment of a mixing element 40 '. In this embodiment, the mixing element 40 'is formed by an angle-shaped component, whose two legs are the same length and enclose an angle of about 115 ° with each other. The position of the mixing element 40 'on the drill pipe 10 is the same as that of the mixing element 40.

As FIGS. 3 a and 3 b illustrate, the mixing element according to the invention can either have a convex outer circumferential surface (FIG. 3 a) or the mixing element can have two outer surfaces converging towards one another (FIG. 3 b). In both cases, the mixing element has on its outer side a surface 42 or 42 ', which extends approximately tangentially to the outer casing of the drill pipe 10, and which serves as a wedge surface, since it with the wall of the drilling head 30 formed by a drill forms a tapered region 44. As a result of these wedge surfaces, the mixture consisting of drilling fluid and soil material is mixed on the one hand in the annular space 30 and, on the other hand, introduced into the wall of the drilling channel so that it is stabilized, which will be described in more detail below during a rotation of the Erdverdrängungsbohrers.

To create a borehole with the above-described Erdverdrängungsbohrer this is lowered in the X direction in the ground and thereby rotated in the arrow direction (Fig. 2 and 3). At the same time, drilling fluid 38 is passed through the tubing 34 by a pumping arrangement (not shown) so that it exits the exit channel 36 at the tip of the drill head 12 into the wellbore 32. The shape of the drill head 12 provided with the teeth 24 ensures that the drilling fluid 38 already somewhat mixed with parts of the soil material.

As the drilling progresses, so does the annulus 30 above the wellbore 12, in which region the mixing element 40 provides intimate mixing of drilling fluid and soil material. At the same time, the mixing element 40 ensures that the mixture located in the annular space 30 is pressed or entered into the wall of the drilling channel by the wedge surface 42 sweeping the mixture located in the region 44 into the wall of the drilling channel. As a result, the pores 46 present in the surrounding soil material are sealed and the wall of the annular space 30 or of the drilling channel is plastered, as it were, and thereby sealed and stabilized. In particular, when using corresponding additives is particularly well achieved that the drill channel has a stabilized wall portion 48 which simultaneously seals the surrounding soil, so that the annulus above the drill head 12 remains filled with drilling fluid, without this penetrates into the surrounding soil and seeps. This is on the one hand ensures that the drill channel remains stable and does not collapse. On the other hand, it is ensured that the friction-reducing effect of the drilling fluid over the entire length of the drill pipe is maintained, whereby the torque required for drilling is considerably reduced. At the same time, the wall thickness of the drill pipe 12 can remain within reasonable limits.

By the mixing element 40, 40 'also a certain imbalance is present, which imposes on the drill a certain rolling motion, which has a positive effect during drilling.

In particular, for larger pipe diameters, a plurality of mixing elements 40 and 40 'can be provided. Also, the mixing element can be arranged obliquely on the outer circumference of the drill pipe. Furthermore, both drill pipe as well as mixing element can also be made of plastic. Also, the mixing element may be curved or curved in the axial direction. Furthermore, it is not essential that the drilling fluid be injected through the interior of the drill head into the wellbore 32. This could also be done through the annulus 30.

LIST OF REFERENCE NUMBERS

10

drill pipe

12

wellhead

14

shank portion

16

Weld

18

tip portion

2021,22,23

ribs

24

teeth

30

annulus

32

well

34

pipeline

36

outlet channel

38

drilling fluid

40, 40 '

mixing element

42, 42 '

wedge surface

44

rejuvenating area

46

pore

48

stabilized wall section

Claims (15)

1. An earth displacement drill comprising a drill tube (10) and a drill head (12) non-releasably fastened to its end, wherein the radius of the drill tube (10) is smaller than the largest radius of the drill head (12), and wherein at least one mixing element (40, 40') extending in the longitudinal direction (X) of the drill tube (10) is provided at the outer periphery thereof,
   characterized in that
   the drill tube (10) extends in a straight line up to the drill head (12); in that the mixing element (40, 40') is rigidly fastened to the outer periphery of the drill tube (10); and in that at least one radially projecting, spiral-shaped rib (20, 21) is provided.
2. An earth displacement drill in accordance with claim 1, characterized in that the mixing element (40, 40') does not project radially beyond the drill head (12) and in particular extends radially outwardly approximately up to the largest radius of the drill head.
3. An earth displacement drill in accordance with claim 1, characterized in that the mixing element (40, 40') is arranged directly above the drill head (12).
4. An earth displacement drill in accordance with claim 1, characterized in that the mixing element (40, 40') includes a volume between it and the drill tube (10) which is particular a closed volume.
5. An earth displacement drill in accordance with claim 1, characterized in that the mixing element (40, 40') is made symmetrical in longitudinal section and/or in cross-section.
6. An earth displacement drill in accordance with claim 1, characterized in that the mixing element (40 40') has at least one wedge surface (42, 42') which, when viewed in cross-section, forms a converging region (44) with the wall (48) of a drill channel formed by the drill head.
7. An earth displacement drill in accordance with claim 1, characterized in that the mixing element (40) has a convex outer surface.
8. An earth displacement drill in accordance with claim 1, characterized in that the mixing element (40, 40') has at least one outer surface extending approximately tangentially to the drill tube (10).
9. An earth displacement drill in accordance with claim 1, characterized in that a plane extending through the central axis (X) of the drill tube forms an angle with the longitudinal axis of the mixing element.
10. An earth displacement drill in accordance with claim 1, characterized in that the longitudinal extent of the mixing element (40, 40') amounts to approximately 150 - 250% of the drill tube diameter.
11. An earth displacement drill in accordance with claim 1, characterized in that the drill head (12) has at least one axially projecting rib (20 - 23) at whose lower side individual teeth (24) are provided which extend in the drilling direction (X).
12. An earth displacement drill in accordance with claim 1, characterized in that the radially projecting rib (20, 21) has individual teeth (24) at its lower side which extend in the drilling direction (X).
13. A method of preparing a bore using an earth displacement drill in accordance with at least one of the preceding claims, wherein the earth displacement drill is bored into the subsurface, a drill fluid is introduced into the ring space arising between the bore and the drill channel and this drill fluid is mixed above the drill head.
14. A method in accordance with claim 13, characterized in that the drill fluid is additionally introduced, in particular pressed, into the wall of the drill channel.
15. A method in accordance with claim 13, characterized in that the drill fluid is guided through the drill tube and the drill head into the bore.

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