FR2819850A1 - PRESSURIZED LIQUID JET DRILLING TOOL - Google Patents

Abstract

The tool comprises a body (40) with a lower end (42) provided with several mechanical cutting parts (44) and with nozzles (46) for creating a pressurized fluid jet for breaking up the ground. It has an upper end (48) provided with connections (50) to a drilling string and a pressurized fluid supply. A valve (56) gives the pressurized fluid jet a temporary non-symmetrical distribution relative to the tool longitudinal axis.

Description

The present invention relates to a liquid jet drilling tool

  under pressure which allows the realization of deviated drilling and a drilling assembly by injection of pressurized fluid using such a tool. The so-called "jet grouting" technique consists in producing concrete columns of soil using a fluid sent at high pressure to destructure the ground. This destructuring operation is performed from a mechanical drilling materializing the axis of the column which will be obtained. The position and in particular the verticality of these columns are very important for the quality of the final work, especially when it must have a sealing function. For example, to obtain a good continuity of a veil resulting from the juxtaposition of columns or that of a solid mass, it is necessary to position very precisely the axes of all the columns constituting this work. To correct positioning errors and in particular verticality errors, directional drilling techniques are used to correct deviations from the axis of the

drilling in progress.

  The technique of directional drilling relies on two systems: on the one hand the detection of the position of the drilling and on the other hand the possibility of deflecting this drilling in the desired direction in order to

  correct the error of verticality or, more generally, the error of direction.

  The techniques commonly used in hard terrain, that is to say essentially in the field of oil drilling, are based on three principles: - the insertion of a bend in the tool line; The use of controlled deflectors that create a lateral force on the tool; and - changing the impact of the tool, for example by making

bend its axis.

  These three techniques are associated with the continuous rotation of the driven drilling tool either by a bottom motor or directly by

  the drill head via the drill string.

  In the coverage areas, other deviated drilling techniques are used. They are based on the sinking of an inclined pallet which is equipped with the tool, this sinking being sometimes assisted by a jet of drilling fluid. To perform the deviation, the rotation of the drill string at the end of which is mounted the tool must be stopped and after orientation, the tool is dark in the ground a few inches before resuming its rotation. This operation is repeated several times until a significant deviation is obtained capable of correcting the steering error. To drill in the normal way, the tool is rotated continuously. In the case of boreholes used for the construction of "jet grouting" columns, these are necessarily located in grounds that can be destroyed by a jet under high pressure,

  that is to say, relatively soft lands.

  A drilling technique used in poorly consistent alluvial terrain consists of destructuring the soil by a jet of pressurized fluid directed towards the front of the tool. This technique is called

  jetting. It is widely used in sandy loams.

  The disadvantage of this drilling principle is that it does not work as soon as

  that he meets a hurdle a little harder.

  A first object of the present invention is to provide a tool

  Directional drilling compatible with the "jet grouting" technique.

  To achieve this object according to the invention, the directional drilling tool for conducting a directional drilling comprises a body having a longitudinal axis, a lower end provided with a plurality of mechanical cutting members and means for creating a jet of fluid under pressure to disintegrate the soil and an upper end provided with connection means to a drill string and means

  supplying fluid under pressure of the jet generating means.

  This drilling tool is characterized in that it comprises means for giving at least temporarily to said jet of pressurized fluid a mean non-symmetrical distribution with respect to said axis.

longitudinal body of said tool.

  In the present text, by means for creating a jet of pressurized fluid means means which make it possible to create a fluid outlet under pressure at the lower end of the drilling tool.

  which may actually consist of a single jet or a plurality of jets.

  In addition, the drilling tool that can be driven by a continuous or alternating rotation movement about its longitudinal axis, by mean non-symmetrical distribution with respect to the longitudinal axis, not only the distribution of the jet to the static state (in the absence of rotation) but also dynamic, that is to say all the positions of the jet or jets during a period of rotation of the tool around

its axis.

  It will be understood that, thanks to the invention in the phases where it is desired to carry out a deflection, it is possible at least temporarily to make the mean distribution of the jet of pressurized fluid asymmetrical with respect to the longitudinal axis of the tool. average dissymmetry resulting in an overall deviation of the tool in the corresponding direction

dissymmetry.

  According to a first embodiment, the tool is characterized in that the means for creating a jet of fluid under pressure comprise q injection nozzles distributed symmetrically with respect to the longitudinal axis of said tool and in that comprises means for temporarily controlling the interruption of the supply of some of said nozzles such that said powered nozzles present

  a non-symmetrical distribution with respect to the longitudinal axis of said tool.

  It will be understood that, in this first embodiment, apart from the deflection phases, the jet of pressurized fluid has a symmetrical distribution with respect to the axis of the tool and the jet is temporarily modified in the deflection phases for introduce a

  asymmetry in the desired direction.

  According to a second embodiment, the directional drilling tool is characterized in that said means for creating the jet of pressurized fluid comprise q pressure injection nozzles, said q nozzles being distributed asymmetrically with respect to the pressure injection nozzle. longitudinal axis of said tool, and it comprises means for feeding

simultaneously said nozzles.

  In this second embodiment, the jet of pressurized fluid is asymmetrical with respect to the axis of the body of the tool permanently and, in the deflection phases, the deflection is thus obtained. On the other hand, apart from the deflection phases, the tool is rotated to make the average distribution of the fluid jet

  under symmetrical pressure over a period of rotation of the tool.

  A second object of the invention is to provide a set of drilling in the ground by injection of fluid under pressure which allows, in certain phases of drilling, to carry out a directional drilling to correct

a drilling direction error.

  To achieve this goal, the set of drilling in the ground by injection of fluid under pressure comprises: - a plurality of drill pipes connected together and provided with a pressurized fluid supply pipe, forming a drill string ; a drill head for controlling the setting in rotation and the vertical translation of said drill string; and a drilling tool attached to the lower end of said drill string and characterized in that said drill bit is in accordance with

  to that which has been defined previously.

  Other features and advantages of the invention

  will appear better on reading the following description of several

  embodiments of the invention given as non-exemplary

  limiting. The description refers to the appended figures in which:

  Figure 1 is an elevational view of a pressurized jet drilling assembly; Figure 2A is a longitudinal sectional view of a drill bit according to a first embodiment of the invention; Figure 2B is a front view of the tool of Figure 2A; Figure 3A is a front view of a drill bit according to a second embodiment; and Fig. 3B is a side view of the tool of Fig. 3A

showing the deviation effect.

  In Figure 1, there is shown a drilling assembly comprising a platform 10 preferably mounted on the tracks 14 or any other displacement system. On the platform 10 is articulated a guide post 16 serving to guide a carriage in translation 18. The carriage 18 supports a drill head 20 for rotating and translational movement of a drill string 22 at the lower end 22a of which is mounted the drilling tool 24. The drilling tool 24

  is of the type capable of creating jets of fluid under pressure.

  The pressure feed is carried out by a source of pressurized fluid 26, preferably a liquid, which feeds a pipe (not shown) disposed inside the drill rods 2, this pipe being able to be constituted by the rods themselves and connected to the latter by a flexible tube 28 and a rotary joint 30. The vertical displacement control of the drill head 20 is provided for example by a cable 32 or chain system, driven by a motor not shown, while the rotation of the drill string is

  realized for example by a motor 34.

  Referring first to FIGS. 2A and 2B, a first embodiment of the drilling tool which bears the reference 24a will be described. This tool comprises a body 40 which has a lower end 42 on which are mounted cutting members such as 44 of conventional type. In the lower face 42 are also provided nozzles such as 46 capable of creating a jet of pressurized liquid substantially along the longitudinal axis X-X 'of the body 40 of the tool. The body 40 of the tool has a second end 48 provided with a thread 50 for connection to the drill string 22. There is also shown in the drill string 22 a supply pipe for pressurized liquid 52. This pipe 52 is connected to such passages

  54 arranged in the body of the tool to feed the nozzles 46.

  As shown in Figure 2A, the nozzle 46a is equipped with a controllable switch 56. In Figure 2B, there are shown four mechanical cutting tools such as 44 and four injection nozzles 46a, 46b, 46c and 46d. These nozzles are arranged at 90 relative to each other. More generally, these nozzles whose number may be different from 4 are arranged generally symmetrically with respect to the axis X-X '

of the tool.

  It is understood that, when the nozzles are fed with pressurized liquid, the nozzles 46b, 46c and 46d permanently create a localized jet of liquid whereas the nozzle 46a creates such a jet or creates no jet according to the state of the switch 56. Switch 56 may for example be controlled by a bistable system whose state depends on the application

temporary overpressure.

  It is understood that, when the tool 24a is not rotated and that the nozzle 46a is closed, the overall jet of liquid under pressure created by the nozzles 46b, 46c and 46d is asymmetrical and will allow the deviation of the trajectory of the tool in the ground. On the contrary, if the nozzle 46a is energized, the overall jet is symmetrical and no deflection occurs. It is possible during the deviation phase to combine the effect

  jets under pressure and the mechanical action of the cutting members 44.

  To maintain the deflection effect, it suffices to cause the alternating rotation of the tool by an angle equal to 90 for example, which does not alter the dissymmetry of the jet, but allows the action of the different cutting tools 360 degrees. More generally, if the tool has n cutting members 40, the alternating rotation will be an angle at least equal to 360 / n degrees and less than 360 degrees to maintain the average dissymmetry jets produced by the nozzles. The motor 34 of the drill head will have to be

ordered accordingly.

  In the embodiment shown in FIGS. 3A and 3B, the drilling tool which bears the reference 24b comprises three cutting members 60 and three nozzles for injecting pressurized liquid 62a, 62b and 62c. The injection nozzles 62a and 62c are closed permanently while the nozzle 62b is permanently open. It would also be possible to provide a tool with only one nozzle. It is understood that when the drilling tool is fed with fluid under pressure, the resulting overall jet is, in the static state, that is to say in the absence of rotation, asymmetrical with respect to the XX 'axis of the drilling tool. It can thus cause the deviation of the tool as shown in Figure 3B. To allow the action of the different cutting members 60, the tool can be given an alternating rotational movement F of an angle equal to 120. Indeed, this rotation allows the action of cutting members 3600 but does not alter the average dissymmetry of the jet of liquid under global pressure produced by the nozzle 62b. More generally, if the tool has n cutting members 40, the alternating rotation should correspond to an angle at least equal to 360 / n degrees to ensure a 360-degree cut. The alternating angle of rotation must respect the asymmetrical mean distribution condition of the jet (or jets) of liquid under pressure. This angle is

  therefore necessarily less than 360 degrees.

  On the other hand, apart from the deflection phases of the tool, it can be imparted to it a continuous rotational movement controlled by the drilling head 20. In fact, on average, the single jet produced by the nozzle 62b occupies all the angular positions relative to the axis XX 'on a complete rotation. We can also cause rotations

  Alternate tool of plus or minus 360 degrees.

Claims (6)

  A directional drilling tool for conducting a directed borehole, the tool comprising a body (40) having a longitudinal axis, a lower end (42) having a plurality of mechanical cutting members (44), and means (46, 62) for creating a jet of pressurized fluid to disintegrate the soil and an upper end (48) provided with means (50) for connection to a drill string and means (52) for feeding pressurized fluid of the jet generating means, said drilling tool being characterized in that it comprises means (56, 62a, 62c) for giving at least temporarily to said jet of pressurized fluid a mean non-symmetrical distribution with respect to said axis longitudinal body of said tool.   2. Drilling tool according to claim 1, characterized in that the means for creating a jet of fluid under pressure comprises q injection nozzles (46) distributed generally symmetrically with respect to the longitudinal axis of said tool and in that it comprises means (56) for temporarily controlling the interruption of the supply of some of said nozzles in such a way that said nozzles will feed a   non-symmetrical distribution with respect to the longitudinal axis of said tool.   3. Drilling tool according to claim 1, characterized in that said means for creating the jet of fluid under pressure comprises q injection nozzles (62) under pressure, said q nozzles being distributed globally unsymmetrically with respect to the axis longitudinal axis of said tool, and in that it comprises means for feeding simultaneously said nozzles.   4. A set of drilling in the ground by injection of fluid under pressure comprising: - a plurality of drill pipes (22) connected together and comprising means for supplying pressurized fluid (28, 30), forming a train of rods; - A drill head (20) for controlling the rotation and the vertical translation of said drill string; and - a drilling tool (24) attached to the lower end of said drill string; characterized in that said drilling tool is in accordance with the claim 1.   5. A set of drilling in the ground by injection of pressurized fluid comprising: - a plurality of drill pipes (22) connected together and and comprising feed means (28, 30) in pressurized fluid, forming a train stems; - A drill head (20) for controlling the rotation and the vertical translation of said drill string; and - a drilling tool (24) attached to the lower end of said drill string, characterized in that said drill bit is in accordance with claim 3 and comprises n cutting members (60) with n> q and in that that the drill head is controlled to cause continuous rotation in the same direction, or alternating rotations of more or less 360 degrees of the drill string during the drilling phases without deviation and that said drill head is controlled to cause an alternating rotation in one direction and the other of the drill string of an angle   at least 360 / n degrees and less than 360 degrees.   6. A set of drilling in the ground by injection of pressurized fluid comprising: - a plurality of drill pipes (22) connected to one another and comprising means (28, 30) for feeding fluid under pressure, forming a train of rods; - A drill head (20) for controlling the rotation and the vertical translation of said drill string; and - a drill bit (24a) attached to the lower end of said drill string, characterized in that said drill bit (24a) is in accordance with claim 2 and has n cutters (44) and during the deflection phases, only r of said nozzles (r <n) are fed with pressurized fluid and the boring head (20) is controlled to cause an alternating rotation in one direction and the other of the drill string d an angle of not less than 360 / n degrees and less than 360 degrees.