EP2652205B1 - Drilling method - Google Patents

Description

The present invention relates to a method of drilling and lining consolidation of a well in a friable ground, for casting a pile or soil recognition, or drilling water and drain, through a hollow rod train operated in rotation or linearly. At the end of the drill string is a drilling tool adapted to the nature of the soil. Near the tool is projected a drilling fluid injected into the drill string and cuttings generated by drilling are removed by surface recovery by the same drilling fluid.

The method of the invention relates to any type of drilling, regardless of its diameter, depth, shape (round, square, rectangular), in any type of soil and whatever its purpose.

The prior art teaches, according to a traditional method of drilling, to use hollow rods placed end to end as drilling progresses, see document US 4972906A . In this case, the ground must be dry to avoid landslide, or the drilling fluid is left in place before being evacuated and immediately replaced by a concrete constituting a pile. Of course, this is not valid for digging a well for oil exploration or soil recognition, because in these cases, the well must remain free.

Thus, it has also been proposed so-called "cased boreholes" of using stems put end to end, as before, but also to introduce into the well, tubes according to the progress of drilling. These are the tubes that hold the ground in this case, in a safe way.

But the disadvantage of this method lies in the fact that the rate of progress is low and that it is heavy and expensive.

There is also a so-called "self-drilling" method, consisting of the use of hollow rods equipped with a drilling tool at their end, and injecting into the well being formed a cement, depending on the progress of the drilling. drilling, which cement is a stake to achieve. But in this case, the rods and the tool are lost to constitute in fact a concrete reinforcement. Of course, this method is not valid for drilling wells for oil exploration or for soil reconnaissance.

Another method is to use auger elements forming helicoids, solid or hollow, adding to each other depending on the progress of drilling. In this case, the excavations are dug and put back in order to then inject the cement.

Depending on the case, all these drilling is carried out using drilling fluid used to remount the cuttings to the surface, and sometimes to hold the ground.

This is how it can be: water; air; a viscous mixture called "GSP"; bentonite, which is a mixture of water and clay; a grout, which is a mixture of water and cement; concrete, which is a mixture of water, cement and gravel.

The same is true for drilling tools that may be different.

Known for example the tricone particularly suitable for any type of terrain, but the larger the diameter of the tricone, the more the drill must be important.

The trilame is also used, rather restricted to clay and silty soils.

For rocky terrain, the "downhole" or "off-hole" hammer will be preferred. This is a direct hit of the tool respectively on the bottom of the soil being drilled, or on the end of the rod carrying said drilling tool.

Also for the rocky terrains, are sometimes used drilling tools known as "cutting button". This tool is made of tungsten and rotates, as in the previous cases.

Finally, is sometimes used a tool called "corer", which tool finds its use in soil recognition, to extract samples. It sometimes requires casing, when deep, to prevent rock fall behind the borehole.

All these drilling methods mentioned above have a major disadvantage related to the fact that the technique must be adapted to the ground, which can change several times on the same site.

These methods are different and often require the intervention of specialists because drillers do not necessarily know all the drilling techniques.

The present invention aims to provide a single and simplified technique regardless of the site, where only the drilling tool is to adapt to the type of terrain.

To this end, the invention relates to a method of drilling and lining consolidation of a well in a friable ground, for the casting of a pile, the search for oil or soil recognition, or drilling d water and drain, by means of a hollow shaft train actuated in rotation or linearly, at the end of which is disposed a drilling tool adapted to the nature of the ground, and near which is projected a drilling fluid injected into the drill string, the cuttings thus generated by the drilling being discharged by surface raising by the same drilling fluid, characterized in that the lining of the wellbore is obtained from a double jet of projection on its wall, on the one hand a slurry of a material having curing characteristics, and secondly a fluid hardener, the first jet occurring immediately behind the drill bit, and the second jet occurring simultaneously behind said first jet.

Thanks to this simple process, there are no more hazards during the recovery of the drill string. The drilling may be intended for the realization of the pile for special foundations, the sounding of soil, the search for oil, water drilling or drain, without concern of holding of ground or time of intervention.

Thus, regardless of the type of drilling, it is no longer necessary to perform casings, or inputs of mud or water to be injected into the hole to hold the walls before pouring a cement. The method mentioned above is adaptable whatever the type of soil or well to achieve.

Another advantage of the method according to the invention lies in the fact that the realization of the well can be made horizontally, vertically or obliquely.

The invention also relates to the features that will emerge during the following description, which should be considered in isolation or in all their possible technical combinations.

• La figure 1 représente schématiquement une machine de forage traditionnelle, équipée d'une rotative ou d'un marteau « hors trou » tel que défini ci-dessus.
• La figure 2 représente schématiquement un train de tiges et son outil de forage, équipé des moyens de chemisage selon le procédé de l'invention, selon un premier exemple de réalisation, c'est-à-dire par entraînement rotatif.
• La figure 3 représente schématiquement un train de tiges et son outil de forage, équipé des moyens de chemisage selon le procédé de l'invention, selon un second exemple de réalisation, c'est-à-dire par entraînement linéaire.
• La figure 4 est une vue en coupe selon la ligne IV-IV de la figure 3.

This description given by way of nonlimiting example, will better understand how the invention can be made with reference to the accompanying drawings in which:

• The figure 1 schematically represents a traditional drilling machine, equipped with a rotary press or an "off-hole" hammer as defined above.
• The figure 2 schematically shows a drill string and its drilling tool, equipped with lining means according to the method of the invention, according to a first embodiment, that is to say by rotary drive.
• The figure 3 schematically shows a drill string and its drilling tool, equipped with lining means according to the method of the invention, according to a second embodiment, that is to say by linear drive.
• The figure 4 is a sectional view along line IV-IV of the figure 3 .

In a manner common to the different modes of application shown, the invention relates to a method of drilling and lining consolidation of a well 1,1A in a friable ground 2, for the casting of a pile, the search for oil or soil recognition, or water drilling and drain, via a train of hollow rods 3.3A actuated in rotation or linearly, at the end of which is disposed a drill bit 4 4A adapted to the nature of the soil 2, and near which is projected a drilling fluid 5 injected into the drill string 3,3A, the cuttings thus generated by the borehole being evacuated by raising to the surface by the same drilling fluid 5.

According to the invention illustrated by the two embodiments shown in the figures, lining 6, 6A of the wellbore 1,1A is obtained from a double jet of projection 7,8-7A, 8A on its wall 9 9A, on the one hand a slurry of a material having curing characteristics, and on the other hand a fluid hardener, the first jet 7.7A intervening immediately behind the drill bit 4,4A, and the second jet 8.8A occurring simultaneously behind said first jet 7.7A, the assembly may be biodegradable depending on the type of drilling to be obtained, for example water drilling or drain.

Depending on the method of application of the process, illustrated in figures 1 and 2 , the device is constituted by a drilling machine 10, generally designated on the figure 1 , supporting the drill string 3 at the end of which is disposed the drill bit 4 itself, which can be a tricone, a cutter, a hammer "downhole" or a trilame. In the example shown, it is a rotary drive or a hammer "off hole" 11.

On the other hand, the embodiment represented on the Figures 3 and 4 differs from the preceding in that the drive of the drilling tool 4A is linearly in the direction "F". The tool 4A is in fact a grab, digging the ground 2 by means of claws 12 closing on themselves after taking the ground up, to bring it to the surface.

According to the two embodiments presented, the method is the same, namely, digging the borehole 1,1A by a drill bit 4,4A and project immediately behind, one or more streams of cement slurry 7,7A, or other, and one or more hardener streams 8,8A on the walls 9,9A.

With the method according to the invention, the drilling can be carried out dry, that is to say without mud and therefore without a specialist in this method.

Preferably, the drilling fluid 5 is air injected under high pressure.

The material having curing characteristics, forming the first spray jet 7,7A, is a cement slurry, or the like.

The cement grout consists of cement or other, and water or other, in proportions allowing the fluidity required.

On the other hand, the grout of cement or other forming the first jet 7,7A and the hardener forming the second jet 8,8A are projected under low pressure or under high pressure.

The use of low pressure avoids the enlargement of the diameter of the borehole 1.1A, during the lining.

The tests demonstrated that the proportions of mixing 1200 kg of cement with 600 liters of water, to obtain one m ³ of grout, gave good results in the projection on the walls of the wellbore.

The piles to be subsequently poured into the wellbores being of substantially identical composition, good catch compatibility will occur with the lining which has been previously made.

The second jet concerning the hardener is therefore a setting accelerator having the effect of lowering, to a few seconds, the setting time of the projected grout constituting the liner, not to say almost immediately.

This liner will have a thickness of the order of 4 to 5 mm. The grout plus the hardener may be replaced by other products according to the technical objective to be obtained for drilling.

In some particular cases, the grout may be reinforced with fibers, steel or other.

This is particularly interesting in the event of a major surge in the ground (swelling clay) or water (groundwater).

According to another characteristic of the invention, the flow rate of the first jet 7.7A is adjusted relative to the advance of the drilling tool 4, 4A, depending on the nature of the terrain 2.

In fact, the hollow carrier rods 3,3A of the drill bit 4,4A comprise three feed circuits, respectively: one for the drilling fluid 5, air in this case; one for grout or other 7.7A liner; one for the 8,8A hardener.

Preferably, the 7,7A-8,8A jets are derived from conical jet nozzles.

According to another characteristic of the invention, the two spray jets 7.7A-8.8A of the grout and the hardener are protected from the upwelling of the cuttings by driving the drilling fluid 5 towards the surface, via a protective screen 13, disposed on the drill pipe 3 interposed between said jets 7,8 and the drill bit 4.

More precisely, the rotary protection screen 13 is composed of an angular sector whose angle is of such value as to protect the jets 7,8, integral with the rod 4, while allowing, in its also rotatable open zone, the passage of excavated material the surface by the drilling fluid 5, during its rotation.

In all cases, the drilling tool 4 is equipped with a reamer, so as to increase the diameter of drilling to take into account the thickness of the liner.

Claims (15)

1. A drilling and lining method for consolidating a well (1, 1A) on a crumbly soil (2) with view to sinking a stake, in searching for petroleum or reconnoitring soil, or drilling for water or a drain hole, via a hollow drillpipe string (3, 3A) actuated in rotation or linearly, at the end of which a drilling tool (4, 4A) adapted to the nature of the soil (2) is positioned and in proximity to which is projected a drilling fluid (5) injected into the string of rods (3, 3A), the spoils thereby generated by the drilling being discharged by moving them up to the surface with the same drilling fluid (5), characterized in that the lining (6, 6A) of the wellbore (1, 1A) is obtained from a dual projection jet (7, 8 - 7A, 8A) on its wall (9, 9A) of a slurry of material having hardening characteristics on the one hand, of a fluid hardener on the other hand, the first jet (7, 7A) intervening immediately behind the drilling tool (4, 4A), the second jet (8, 8A) intervening simultaneously behind said first jet (7, 7A), the whole may be biodegradable depending on the type of borehole to be obtained.
2. The method according to claim 1, characterized in that the drilling is carried out under dry conditions.
3. The method according to claim 2, characterized in that the drilling fluid (5) is air under high pressure.
4. The method according to one of claims 1 to 3, characterized in that the material having hardening characteristics, forming of the first projection jet (7, 7A) is a slurry of cement or other material.
5. The method according to one of claims 1 to 4, characterized in that the cement slurry forming the first jet (7, 7A) and the hardener forming the second jet (8, 8A) are projected under low pressure or under high pressure.
6. The method according to one of claims 4 or 5, characterized in that the cement slurry is reinforced with fibers.
7. The method according to one of claims 1 to 6, characterized in that the flow rates of the first jet (7, 7A) is adjusted relatively to the advance of the drilling tool (4, 4A), depending on the nature of the soil (2).
8. The method according to one of claims 1 to 7, characterized in that the hollow bearing rods (3, 3A) of the drilling tool (4, 4A), include three supply circuits, respectively: one for the drilling fluid (5); one for the lining slurry (7, 7A) or other slurry; one for the hardener (8, 8A).
9. The method according to one of claims 1 to 8, characterized in that both jets (7, 7A - 8, 8A) for projecting the slurry or other slurry and the hardener are protected from upward movements of spoils being carried out by driving the drilling fluid (5) towards the surface, via a protective screen (13) positioned on the drilling rod (3) as an interposition between said jets (7, 8) and the drilling tool (4).
10. The method according to claim 9, characterized in that the rotary protective screen (13) is composed with an angular sector, the angle of which is of a value such as to protect the jets (7, 8), interdependent with the rod (4), while allowing, in its also rotary open area, the passage of the spoils moved up to the surface by the drilling fluid (5), during its rotation.
11. Hollow bearing rod with a drilling tool fitted at one end for the implementation of the procedure mentioned in claims 1 to 10.
12. Hollow bearing rod according to claim 11, characterised in that the bearing rod consists of three power circuits, respectively: one for the drilling fluid (5); one for the lining slurry (7, 7A) or other slurry; one for the hardener (8, 8A).
13. Hollow bearing rod according to claim 12, characterised in that the power circuits for the lining slurry or other slurry and the hardener are fitted with conical jet pressure nozzles.
14. Hollow bearing rod according to Claim 13, characterised in that the nozzles are positioned on the bearing rod immediately behind the drilling tool.
15. Hollow bearing rod according to Claim 13, characterised in that the nozzles are positioned on the bearing rod to project jets of cement slurry and hardener on the surfaces.

Images