EP1514995B1 - Drilling rig with rotating head - Google Patents

Description

The subject of the present invention is a rotary head drilling installation comprising means for correcting the trajectory of the head and in particular means for verticality correction when the drilling is vertical.

More specifically, the present invention relates to such a drilling installation that can be controlled automatically, with regard to the correction of possible errors in drilling trajectory and in particular verticality.

When drilling bored piles using a rotating drill head driven by a drill string, many parameters can affect the verticality of the drilling actually performed. These parameters are in particular the inhomogeneity of the ground that meets at the same depth the drilling head or the necessarily limited stiffness of the drill string. When the drilling must be performed at a great depth, for example of the order of 100 meters, it is understood that a deviation even at a reduced angle relative to the vertical can cause a positioning error of the bottom of the borehole. However, in a large number of cases, it is impossible to tolerate such differences, because of the tolerances imposed by the specifications of the work.

More generally, it may be necessary to carry out non-vertical drilling, for example drilling having their full depth an inclination noted relative to the vertical or drilling with several portions, each portion having a proper inclination relative to the vertical . In these situations, it is important that the drilling performed respects the inclination or inclination defined by the specifications of the structure.

It is therefore very desirable to have a drilling rig of the rotary head type which makes it possible to correct any errors of trajectory.

In the present text, the term "trajectory error" means that the drilling actually carried out using the rotary tool is at an angle to the path planned for drilling. Most often, the planned path of the drilling is vertical and one will thus be led to detect errors of verticality.

It is also understood that it is highly desirable that the means used to correct this trajectory error do not lead to periods of unavailability of the drilling head significant.

In Figure 1 attached, there is shown an installation of known type drilling rotary cutting head. In this figure, there is shown the borehole 10 in progress with its casing 12. At the upper portion 14 of the casing 12 is mounted a head 16 for rotating and translational movement of the cutting head. The rotation and displacement head 16 is connected to the cutting tool 18 by a rotating rod train 20. At regular intervals, the drill string 20 is preferably equipped with stabilizing fins such as 22 which ensure a certain centering of the drill string 20 in the borehole. The lower end 20a of the drill string is connected to the cutting tool 18 via two stabilizing drums 24 and 26. Of course, there could be only one stabilizing drum. In the following description, the stabilizing drums 24 or 26 will be called "stabilizers". The stabilizing drums 24 or 26 are parts constituted by an outer cylindrical skirt whose diameter is slightly smaller than that of the cutting tool 18 but much greater than that of the drill string. As will be explained in more detail later, the stabilizer 24 or 26 is rotatably mounted around the drill string 20 but immobilized in translation. The drum or stabilizers 24 or 26 allow (s) to provide a certain orientation or trajectory to the cutting tool 18. However, even with the presence of these stabilizers, the path of the cutting tool can not be most often provided with the required tolerance.

In the case of the production of bored piles, the case of the invention, the rods have a diameter of 200 to 400 millimeters and the diameter of the borehole is at least 1000 millimeters and most often at least 1500 millimeters. The diameter of the stabilizing drums is also at least 1,000 to 1,500 millimeters and thus at least three times greater than that of the rods.

An object of the present invention is to provide a drilling rig with rotary cutting head of the type described in particular with reference to Figure 1 but which comprises tool path correction means for respecting the desired theoretical path.

To achieve this object, according to the invention, the drilling installation equipped with trajectory correction means is designed as in claim 1.

WO-A-0236924, US-A-5931239, US-A-5547031 and US-A-5467834 all relate to drilling rigs in which the drill bit, and thus the drilling itself, has a diameter only slightly greater than that of the drill string.

Accordingly, none of these documents relates to the problem that aims to solve the invention defined by claim 1, namely the correction of the trajectory of the drill bit in the case of drilling diameter greater than 1000 mm.

Claim 1 differs from said documents not only in the diameter of the borehole but also in the fact that the stabilizer is close to the drill head and has a diameter smaller than that of the rotary drill head and at least three times greater than that of the drill string.

It is understood that when the path error is detected for example by means of sensors mounted on the cutting tool, the drill string is stopped. Then, it controls the rotation of the drill string to bring the support pad in the angular orientation corresponding to the path correction to be made. This orientation having been achieved, the displacement means are controlled to apply the support pad against the wall of the borehole.

The rotation and movement of the drill string and thus of the cutting tool are then reordered, the action of the bearing pad to correct the path of the rotary cutting tool.

It should further be emphasized that since the pad constitutes a part of the side wall of the stabilizer, it can fully fulfill its guiding role outside the error correction phases of trajectory.

According to a first mode of implementation, preferably, the means for angular orientation of the pad comprise first abutment means, integral in rotation, said stabilizer and second abutment means integral in rotation of the drill string and movable relative to the drill string to assume a first operative position in which the first and second abutment means can cooperate to transmit the rotation of the drill string to said stabilizer.

More preferably, said second stop means comprise an orientation cylinder whose body is integral with the drill string and whose rod is movable parallel to the axis of the drill string. In the extended position, the end of the rod of said jack is able to cooperate in rotation with the first stop means.

According to this preferred embodiment, it is understood that when the orientation cylinder is not activated, there is no connection in rotation between the drill string and the stabilizer. On the other hand, when the jack is activated, the end of its rod cooperates with the stop carried by the stabilizer, which makes it possible to give the stabilizer and thus the support pad the desired orientation. When this orientation is obtained, the orientation cylinder is deactivated and the mechanical connection in rotation between the drill string and the stabilizer is eliminated.

• la figure 1 déjà décrite montre une installation de forage à tête rotative de coupe de type connu ;
• la figure 2A montre en coupe verticale un premier mode de réalisation du système de correction d'erreur de trajectoire ;
• la figure 2B est une vue en coupe horizontale selon la ligne B-B de la figure 2A ; et
• la figure 3 illustre une variante de réalisation du système de correction d'erreur de trajectoire.

Other characteristics and advantages of the invention will appear better on reading the following description of several embodiments of the invention given by way of non-limiting example. The description refers to the appended figures in which:

• Figure 1 already described shows a drilling rig rotary head cutting known type;
• FIG. 2A shows in vertical section a first embodiment of the trajectory error correction system;
• Figure 2B is a horizontal sectional view along line BB of Figure 2A; and
• FIG. 3 illustrates an alternative embodiment of the trajectory error correction system.

Referring now to FIGS. 2A and 2B, a first embodiment of the trajectory error correction system will be described. This system as already explained is made from the stabilizer 40 which is mounted on the drill string 20 near the cutting tool not shown in these figures.

The stabilizer 40 consists essentially of a cylindrical outer wall 42 of axis X, X '. The side wall 42 is completed by two annular end portions 44 and 45. The stabilizer 40 also comprises in simplified manner an axial sleeve 46 which is engaged around the rods 20 of the drill string. This sleeve is mechanically connected to the side wall 42 for example by radial arms not shown in the figures. As shown in Figure 2A, the rod 20 on which the stabilizer 40 is mounted comprises two fixed annular rings 48 and 50 which act as a stop to limit the possibilities of translational movement of the stabilizer 40 along the rod 20. However, as already explained, the stabilizer 40 is free to rotate around the rod 20.

According to the invention, a part of the side wall 42 of the stabilizer 40 constitutes a separate part 52 which therefore has the shape of a cylindrical surface portion. This separate portion 52 which forms a support pad on the borehole wall is movably mounted relative to the rest of the stabilizer by means of displacement cylinders, for example the four jacks referenced 54 in the figures. These cylinders, preferably hydraulic, have a body 55 which is secured by any suitable means of the main part of the stabilizer 40 and whose ends 56a of the rods 56 are integral with the pad 52 also by any suitable means. The rods 56 of the cylinders 54 can move in planes orthogonal to the axis X, X 'and in directions y, y' parallel to the median plane P, P 'of the stabilizer. Thus, the shoe 52 can be moved using the jacks 54 between a retracted position shown in Figure 2B in which the shoe 52 constitutes a continuity of the side wall 42 of the stabilizer itself and an output position shown in dotted line on the Figure 2B. In this extended position, the pad 52 is applied with pressure against the wall of the borehole or against the casing when it is provided. It is understood that this action of the shoe 52 against the bore wall transmits a force to the drill string 20 and therefore to the axis of rotation of the cutting tool 18 to modify the path of the cutting tool and thus correct the axis of the drilling performed.

To obtain the correction of the desired trajectory, it is of course necessary, before causing the exit of the support pad 52, to give the latter the angular orientation corresponding to the correction of the trajectory to bring. This orientation of the shoe 52, that is to say the stabilizer 40 is obtained by performing a temporary mechanical connection in rotation between the drill string and the stabilizer 40. When this temporary connection is made, by controlling the rotation of the train of stems of a predetermined angle, the same rotation is communicated to the stabilizer 40 and therefore to the support pad 52. Once this orientation is achieved, the mechanical connection between the drill string and the stabilizer is interrupted. The rotary cutting tool is then restarted. The action of the pad 52 on the tool makes it possible to correct the error of trajectory. If the relative displacement length of the pad with respect to the drill string defined by the annular rings 48 and 50 and which is for example of the order of one meter is insufficient to obtain the desired correction, the following operations must be performed: disable the pad 52 to allow the descent of the stabilizer 40 along the rod 20 until it bears on the lower annular ring; proceed to a new orientation of the pad 52; and restoring the pad on the wall of the borehole after the pad has been reoriented.

• un vérin d'orientation 60 est rendu solidaire de la tige 20 sur laquelle est monté le stabilisateur. Ce vérin d'orientation comporte un corps 62 qui est donc solidaire de la tige 20 et dont l'axe est parallèle à l'axe de la tige 20. La tige 64 du vérin d'orientation 60 peut donc se déplacer entre une position rentrée représentée sur la figure 2A en traits pleins et une position sortie représentée en pointillé sur la figure 2A, position dans laquelle l'extrémité 64a de la tige 64 du vérin, peut venir par rotation en butée sur une butée mécanique fixe 66 montée sur la partie 44 du stabilisateur 40. Ainsi, lorsque la tige 64 du vérin 60 est sortie, on réalise une liaison mécanique temporaire en rotation du stabilisateur et donc du patin 52 avec la tige 20. On réalise ainsi l'orientation angulaire du patin. Lorsque le patin 52 est amené en position d'appui contre la paroi du forage à l'aide des vérins 54, la tige 64 du vérin d'orientation 60 peut être rentrée de telle manière que le stabilisateur 40 soit à nouveau libre en rotation autour de la tige 20.

In the embodiment shown in FIGS. 2A and 2B, the temporary mechanical connection is obtained as follows:

• an orientation cylinder 60 is made integral with the rod 20 on which is mounted the stabilizer. This steering cylinder comprises a body 62 which is thus secured to the rod 20 and whose axis is parallel to the axis of the rod 20. The rod 64 of the steering cylinder 60 can therefore move between a retracted position 2A in solid lines and an output position shown in dashed lines in FIG. 2A, in which position the end 64a of the rod 64 of the jack can come to rotate in abutment with a fixed mechanical stop 66 mounted on the part 44 of the stabilizer 40. Thus, when the rod 64 of the cylinder 60 is output, a temporary mechanical connection is made in rotation of the stabilizer and therefore the pad 52 with the rod 20. The angular orientation of the pad is thus carried out. When the shoe 52 is brought into a bearing position against the wall of the bore using the jacks 54, the rod 64 of the steering cylinder 60 can be retracted in such a way that the stabilizer 40 is free to rotate again around of the stem 20.

Preferably, the orientation cylinder 60 is a double-acting hydraulic cylinder. We can thus use the same liquid supply under pressure than for the cylinders 54 which will be described later a preferred embodiment of their supply.

FIGS. 2A and 2B also schematically show the control of the jacks 54 for moving the shoe 52. In the embodiment shown, the supply of liquid under pressure is carried out via a pipe connected to the rods. 20. The rod 20 on which the stabilizer 40 is mounted is equipped with a rotary joint 70. This rotary joint comprises a first portion 72 secured to the rod 20 and connected to the pressurized liquid supply line and a moving part. 74. This mobile part 74 is equipped with a pipe 76 which enters the stabilizer 40. The pipe 76 is divided into four supply lines such as 78 to supply each of the cylinders 54.

In FIGS. 2A and 2B, the initial orientation of the support pad 52 is achieved by the temporary mechanical connection in rotation resulting from the action of the rod 64 of the steering cylinder 60 on the mechanical stop 66 secured to the stabilizer 40 .

FIG. 3 is a simplified representation of an alternative embodiment in which the temporary rotational connection always comprises the orientation jack 60, but this latter can cooperate in the extended position with a mechanical stop 80 integral in rotation with the part In this case, of course, there must be a sufficient mechanical connection between the stabilizer 40 and the mobile part 74 of the rotary joint. This mechanical connection may be of any suitable type and for example by metal rods such as 82 connecting the movable portion 74 of the rotary joint to the wall at the upper portion 44 of the wall of the stabilizer 40. Of course, between the movable portion of the rotary joint 70 and the stabilizer 40, there remains the connecting pipe 76 for supplying the cylinders 54 in liquid under pressure. In contrast, the fixed mechanical stop 66 is removed.

In the foregoing description, the steering cylinder 60 is a hydraulic cylinder. We would not go beyond the invention if this cylinder was pneumatic. In this case, the rods 20 must be equipped with pressurized air supply lines 67 and 68 connected to the anterior chambers 60a and posterior 60b of the jack.

It is also understood that, preferably, the control members of the correction system are cylinders. They can therefore be controlled automatically and remotely.

As already explained, in the context of the invention, the stabilizer has a diameter which is at least three times greater than that of the rods. In addition, the outer diameter of the stabilizer is close to that of the rotary cutting tool and therefore that of the drilling.

In addition, at rest, the trajectory correction pad is a part of the side wall of the stabilizer.

As a result, the stroke of the correction pad to move from its rest position to the active position is very small. It is the same for the cylinders that control the skate. The mechanical forces to which these cylinders are subjected are reduced.

Claims (9)

1. Drilling apparatus provided with trajectory correction means comprising, to create bore-holes having a diameter equal to at least 1 000 mm:

   - a rotary drilling head (18);

   - a string of rods (20) to cause the rotation and raising/lowering of the said drilling head;

   - means (16) for controlling the rotation of the string of rods; and

   - a stabilizer (40) mounted to freely rotate about the string of rods in the proximity of the said drilling head, the said stabilizer having a substantially cylindrical lateral wall the diameter of which is smaller than that of the rotary drilling head and at least three times greater than that of the string of rods,
   a part of the said lateral wall (42) of the stabilizer (40) forming an abutment part (52) moveable relative to the remainder of the stabilizer in a radial direction relative to the string of rods,

   - means (54) for displacing the said abutment part (52) between a rest position in which it is substantially arranged in the lateral wall (42) of the stabilizer and an active position in which it projects from the said lateral wall to come into abutment against the wall of the bore-hole;

   - means for controlling the means for displacement of the abutment part; and

   - means (64, 66, 80) to temporarily give the abutment part a predetermined angular orientation.
2. Drilling apparatus as described in claim 1, characterised by the fact that the said stabilizer (40) is mounted freely in translation relative to the string of rods (20) between two stops (48, 50) attached to the string of rods.
3. Drilling apparatus as described in any one of claims 1 and 2, characterised by the fact that the means for angular orientation comprise first means forming a stop (66, 80) attached in rotation to the said stabilizer (40); and second means forming a stop (60, 64) attached in rotation to the string of rods (20) and moveable relative to the string of rods to adopt a first active position in which the first and second means forming a stop can co-operate to transmit the rotation of the string of rods to the said stabilizer.
4. Drilling apparatus as described in claim 3, characterised by the fact that the said second means forming a stop comprise a ram (60) the body (62) of which is attached to the string of rods (20) and the rod (64) of which is moveable parallel with the axis of the string of rods, in the extended position, the end of the rod (64a) of the said ram being able to co-operate in rotation with the first means forming a stop (66, 80).
5. Apparatus as described in claim 4, characterised by the fact that the said ram (60) is an hydraulic ram.
6. Apparatus as described in claim 4, characterised by the fact that the said ram (60) is a double acting pneumatic ram.
7. Drilling apparatus as described in any one of claims 3 and 6, characterised by the fact that the said first means (66) forming a stop are mounted on the said stabilizer.
8. Drilling apparatus as described in any one of claims 3 to 6, characterised by the fact that the said means for displacement of the abutment part comprise at least an hydraulic ram (54) the body of which is attached to the stabilizer (40) and the end of the rod (56) of which is attached to the abutment part (52).
9. Drilling apparatus as described in claim 8, characterised by the fact that the hydraulic ram (54) is supplied with liquid by a circuit comprising the rods (20) of the said string of rods, a swivel-joint (70) comprising a first part (72) attached to the string of rods and a second part (74) moveable relative to the first part and attached in rotation to the said stabilizer and by a pipe (76) connecting the said second part of the swivel-joint to the said hydraulic ram.

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