EP0212316A1 - Drill string for deflection drilling, method of using such a string and deflecting device used in this string - Google Patents

Abstract

The present invention relates to the production of deflection drilling. Is inserted into the drilling column, between a stabilizer and an active motor element, a device which, according to the direction of rotation of this column, takes a rectilinear configuration ensuring rectilinear drilling or a bent configuration transforming it into a bent connection and ensuring curved drilling; this device comprises two superimposed sleeves (1, 2), one of which rotates by a limited angle around a pivot (3) whose axis (14) makes the same small angle (A) with the axes (10, 10A) of these two sleeves.

Application to petroleum and geothermal drilling.

Description

The present invention relates to the drilling of the basement.

It applies in particular to the search for or the exploitation of oil or gas deposits, or of water layers, hot or not, when circumstances do not allow or make it undesirable to reach an underground target by drilling a rectilinear vertical or oblique well. An obstacle in the basement, even known in advance, can for example cause the inclination or the azimuth of the borehole to change at a point located at greater or lesser depth. It is the same when a layer of low height more or less inclined, even horizontal, must be traversed over a great length by the drilled well.

In such cases deviations from the well must be planned from the start.

In addition, even in the case of vertical drilling, it happens that the rocks encountered cause an unwanted deviation from the axis of the drilling. This parasitic deviation must be compensated by a voluntary deviation which can be called "correction deviation". Whatever the reason that makes them necessary, the deflection operations then begin by measuring the inclination and the azimuth of the axis of the section of the well being drilled, as well as the position reached, the latter measurement resulting from the determination of the lengths, inclinations and azimuths of all the sections already drilled. Once these measurement operations have been carried out, the deviation should be carried out. A drilling method used for this comprises a succession of distinct drilling steps, namely rectilinear drilling steps during each of which a section of rectilinear well having a rectilinear axis is drilled, and at least one curved drilling step. The latter is interposed between two straight drilling steps. During its duration, a section of curved well is drilled, the axis of which is curved substantially in an arc of a circle and is connected to the axis of the preceding straight well section. Similarly, the axis of the following rectilinear section will be connected to that of this curved section.

We use, during each of these drilling steps, a tool attack with an axis in a top-bottom direction (rear-front if the drilling is horizontal), and suitable for attacking downwards (the front) and possibly laterally the rock at the bottom of the well. A bottom motor is attached to the top (rear) of this tool to drive it, and has an axis in line with that of the tool. Tubes, called in the drill pipe profession, are fixed above (at the rear) of this motor one after the other and form a "train" up to the mouth of the well to bring to the bottom a pressurized drilling mud which transports the energy necessary for the motor, to control from the surface of the ground the force of support of the tool against the rock, to possibly drive the whole in rotation, and to carry the tool and the engine when they are raised or lowered into the well.

(In general, it should be understood that expressions such as top and bottom, or top and bottom, etc. should be replaced hereinafter by back and front or back and front and etc., respectively, when drilling progresses horizontally) .

The rods have axes extending that of the engine and extending from each other. Their number is gradually increased by adding new rods as the well deepens. The diameters of this motor and of these rods are less than the normal drilling diameter dug by the tool and the rods have sufficient flexibility so that the drill string formed by the elements described above can follow the curved sections of drilling.

It is known to carry out the curved drilling steps by incorporating a deflection device in the drilling column at the top of the downhole motor which drives the attack tool. This device is an elbow fitting which inclines the common axis of the tool relative to that of the rest of the column. The downhole motor can also be bent. Another deflection procedure uses eccentric stabilizers. Such a stabilizer forms at least one asymmetrical radial projection whose apex is at a distance from the axis of the column slightly greater than a normal radius equal to half the normal drilling diameter. It relies therefore against the wall of the wellbore and separates the axis of the downhole motor from the axis of the well with elastic bending of the column, so as to angularly offset the direction of attack of the tool relative to the axis of the section of well being drilled and thus giving this section the desired curved shape.

The downhole motor is generally a turbine or a motor of the sparrow type.

In some of these known methods, the entire drilling column is reassembled each time it is desired to drill a straight section after a curved section, in order to remove the deflection device such as an elbow connector, the elbow motor or the stabilizers. eccentric, and also each time you want to make a new deviation, because it is then necessary to replace this device. These operations of raising and lowering the drill string include in particular the dismantling and reassembly of all the rods of the column, successively. They take a significant fraction of the time necessary to carry out a deviation, this realization including the measurement operations previously indicated and the drilling of the curved section of well which ensures the desired change of direction. However, this time constitutes an important element in the cost of drilling.

According to another known method using eccentric stabilizers, the drilling of a rectilinear section is obtained, after that of a curved section, by resetting the drilling column to rotate. The tool then drills a hole with an enlarged diameter. This method avoids expensive backwash and lowering of the lining, but it has the drawback of stressing the downhole motor by significant bending stresses.

This other known method is for example described in European patent application EP-A 2 No. 0 085 444 (Shell)

Still other known methods use a controllable deflector device, in particular a controllable elbow fitting constituting a section of the drill string above the downhole motor. Such a device takes command either during the curved drilling steps, a bent configuration, or during the drilling steps, a straight configuration which maintains or restores the straightness of the column. It comprises two successive sleeves which can pivot relative to each other about a pivot axis making the same small angle with the axes of these two sleeves. The pivoting is controlled either with the aid of axial displacement of the upper part of the column or with the aid of a pivoting motor driving a gear as described in US Patent No. 4,303,135 (Benoit).

Such controllable deflector devices have the drawback of being complex.

The object of the present invention is to follow successive curved and rectilinear drilling steps without wasting time while making the drilling tool work under always good conditions, this using a simpler controllable deflection device. according to the above-mentioned Benoit patent.

Its particular subject is a drilling column for deviation drilling, this column having an axis at all points along its length and comprising, as known from the aforementioned Benoit patent,
a rotary drilling tool carried by a tool shaft at the bottom of the column, this tool having a tool axis which at the same time locally constitutes the axis of the column,
an active element of a downhole motor for driving this tool in rapid rotation relative to this column,
a pivot element of this same motor placed between this active element and this tool and carrying said tool shaft for transmitting to this tool an axial thrust applied to this column while allowing the rotation of this tool,
a controllable deflecting device which can take an angled configuration to locally bend the column in order to produce a curved drilling section, and which can take a rectilinear configuration to restore the rectilinearity of the column in order to produce a straight drilling section,
- and a succession of drilling tubes to allow, from the ground surface, to apply an axial thrust to said pivot element, and to drive the entire column in slow rotation,
- Said diverter device comprising a lower sleeve constituting a section of said drill string above said tool, and having an axis which is locally the axis of this column and which is integral with said tool axis,
an upper sleeve constituting a section of said drilling column above said lower sleeve, and having an axis which is locally the axis of this column,
- And pivoting means connecting these two sleeves, these means having a pivot axis inclined at the same small angle relative to the two axes of these two sleeves and now these two sleeves relative to each other while allowing a rotation of the lower sleeve relative to the upper sleeve around this pivot axis, a "alignment" position of this lower sleeve ensuring the alignment of the axes of these two sleeves, to put this device in its rectilinear configuration, a "deflection" position of this sleeve creating a deflection angle between the axes of these two sleeves to put the device in its bent configuration, these pivoting means leaving a free passage inside the column at least for a mud of drilling.

The column according to the invention is characterized in that said pivoting means of the deflection device allow only the lower sleeve to rotate on a limited angular sector of pivoting around said pivot axis, said alignment and deflection positions being defined by stops at both ends of this sector,
- This column comprising, below the deflector device and above the tool, a member rubbing against the wall of the well so that a rotary drive of this drilling column in a normal direction causes a friction torque which brings about the lower sleeve in abutment at said alignment end of the pivoting sector, and so that a rotary drive of the drill string in the opposite direction causes a friction torque to appear which brings this sleeve into abutment at said deflection end , means being provided to maintain this sleeve at this deflection end in the absence of rotation of the column.

According to a preferred arrangement, said diverter device is placed between said active motor element and said pivoting and it is axially traversed by a coupling ensuring the transmission of the movement of this motor to said tool shaft, this motor driving this coupling in rotation in said normal direction, so that the friction of this shaft in this pivoting element tends to cause and maintaining said lower sleeve in abutment at said deflection end in the absence of rotation of the drill string.

Said rubbing member is advantageously constituted by a stabilizer which is used at the same time in a known manner to maintain the column in the axis of the well in the vicinity of the tool and thus to guide the latter.

Said pivoting means consist of a pivot of generally tubular shape elongated along said pivot axis, with a lateral surface constituting guide surfaces which are cylindrical of revolution around this axis and which cooperate with the interior surface of a housing formed in one of said sleeves which constitutes a movable sleeve, to guide the rotation of this movable sleeve, this pivot also comprising a retaining shoulder cooperating with an internal shoulder of this sleeve to prevent its axial displacement and keep it in contact with the other of said sleeves, which is a fixed sleeve, this pivot further comprising retaining means and angular locking means for immobilizing it in said fixed sleeve, this pivot or this movable sleeve finally comprising a projection extending in an angular sector hollow in this movable sleeve or this pivot, respectively, to allow said rotation of the lower sleeve relative to the sleeve higher over a limited angular sector.

The present invention also relates to a method of drilling wells with deviations, this method being characterized in that a column is used according to claim 1,
this drill string being driven in continuous rotation in said normal direction from the ground surface during rectilinear drilling steps to maintain said lower sleeve in abutment at said alignment end of the pivoting sector,
- the transition from a straight drilling step to a curved drilling step comprising the following steps:
- temporary drive of the drilling column in rotation in said opposite direction from the ground surface to bring said sleeve lower in abutment at said end of deflection of the pivoting sector,
- And measurement of the angular position of the lower end of the drill string around its axis and limited continuation of the rotational drive of this column in the opposite direction so that this axis arrives in a predetermined plane of curvature in which a section of curved well must be drilled,
said curved drilling step then taking place without rotation of the drill string,
- And the transition from a curved drilling step to a straight drilling step by resuming the rotation of the drilling column in the normal direction.

Preferably, in this method, during the passage to a curved drilling step, after said step of limited pursuit of the rotational driving of the drilling column in the opposite direction, a column twisting step is provided during which the drilling column is rotated in the normal direction to prevent the elastic torsional torque which has appeared in the column subsequently causing the axis of said lower sleeve to exceed said plane of curvature.

• La figure 1 représente une vue en élévation de la partie inférieure d'une colonne de forage selon l'invention au cours d'une étape de forage rectiligne.
• La figure 2 représente une vue en élévation de la même partie de la même colonne au cours d'une étape de forage courbe, c'est-à-dire pendant une opération de déviation du forage.
• La figure 3 représente une vue à échelle agrandie d'une partie III de la colonne de la figure 1, en coupe par un plan passant par l'axe de cette colonne, pour montrer un dispositif selon l'invention, le pivot de ce dispositif étant représenté non coupé.
• Les figures 4 et 5 représentent deux vues de la même partie de colonne que la figure 3 en coupe par deux plans perpendiculaires à l'axe de cette colonne et repérés IV-IV et V-V, respectivement, sur la figure 3.

With the aid of the attached diagrammatic figures, a description will be given more particularly below, by way of nonlimiting example, of how the invention can be implemented. It should be understood that the elements described and shown can, without departing from the scope of the invention, be replaced by other elements ensuring the same technical functions. When the same element is represented in several figures, it is designated therein by the same reference sign.

• FIG. 1 represents an elevation view of the lower part of a drilling column according to the invention during a rectilinear drilling step.
• FIG. 2 represents an elevation view of the same part of the same column during a curved drilling step, that is to say during a drilling deflection operation.
• FIG. 3 represents an enlarged view of part III of the column of FIG. 1, in section through a plane passing through the axis of this column, to show a device according to the invention, the pivot of this device being shown uncut.
• FIGS. 4 and 5 represent two views of the same column part as FIG. 3 in section through two planes perpendicular to the axis of this column and marked IV-IV and VV, respectively, in FIG. 3.

In accordance with FIG. 1, the lower part of a generally cylindrical drilling column of revolution is rotated from the ground, at a low speed, for example 80 revolutions per minute, in a direction which can be called "direction normal ", in particular to facilitate the descent of the column as the drilling tool 51 works.

Drilling mud is injected into the drill string from the ground surface. It crosses successively, from top to bottom,
- A downhole motor, or more precisely an active motor element 50 responsible for driving the drilling tool 51 in rotation and for this receiving its energy from the mud under pressure. This motor can advantageously be of the known type called "Sparrow motor". It can for example rotate at 300 revolutions per minute like tool 51.
- A tubular deflector device 1, 2, according to the invention, this device being here in its rectilinear configuration which gives it the form of a rectilinear tube coaxial with the column, that is to say not creating any deviation from this drilling stage,
- A pivot element (cartridge) 30 to support the axial forces of the motor 50 and the tool 51 while allowing them to rotate at high speed.
- A stabilizer 31 comprising blades which are arranged in radial axial planes and project radially to keep the column in the axis of the hole
- and the drilling tool 51.

The reference 60 designates the "engine assembly" comprising the actual engine 50, the pivoting cartridge 30 and the stabilizer 31.

The mud leaving by the drilling tool 51 rises in the conventional manner around the drilling column to the ground surface, entraining the rock debris formed by the working of the tool.

The same part of the column is shown in Figure 2 with the diverter device according to the invention in its bent configuration for drilling a curved well section.

In Figure 3 the diverter device according to the invention is shown in its straight configuration. It presents the arrangements previously mentioned according to the invention.

It comprises :
a lower sleeve 1, the lower end of which is arranged to receive the pivoting cartridge 30 coaxially and the upper part of which has arrangements intended to receive a pivot 3,
an upper sleeve 2, the upper end of which is arranged to receive the motor element 50 coaxially and the lower part of which has arrangements intended to receive the pivot 3,
a tubular pivot 3, which has a lower shoulder 5, a key 6 and a threaded upper end 7,
- a locking nut 4 cooperating with the threaded end 7 to press the sleeves 1 and 2 one against the other between the shoulder 5 and this nut
- And O-rings 52 to prevent drilling mud from being inserted between the rubbing surfaces.

Faces 8 of the sleeve 1 and 9 of the sleeve 2 are planar section faces bearing one against the other. They are oblique to the common axis 10, 10A of the outer surfaces 11 and 12 of these sleeves: Their plane intersects the axis 10 at a point 0 and is very slightly moved away from the plane perpendicular in 0 to the axis 10. Their axis 14 passing through 0 is also the axis of pivot 3 and makes a very small angle A with axis 10, for example from 0 to 10 degrees.

The connector is ready to be used when the nut 4 is locked on the pivot 3 and its face 15 and the shoulder 5 are pressed without play on the faces of corresponding housings machined in the sleeves 1 and 2.

The key 6 of the pivot 3 is adjusted in the sleeve 2 and rests thereon on its faces 21 and 22.

On the other hand, during the rotation of the pivot, it evolves between the end faces 23 and 24 of a housing in the form of a wider angular sector machined in the sleeve 1. Its pivot angle constitutes the angular sector of pivoting mentioned above. .

During rectilinear drilling, the sleeve 2 is rotated in a clockwise direction constituting the normal direction previously mentioned. The sleeve 1, linked to the pivoting cartridge 30, itself equipped with a stabilizer 31, is slowed down by the friction of the stabilizer 31 on the ground.

The drive of the sleeve 2 causes that of the pivot 3 by the key 6. The latter then comes to bear on the face 24 of the angular sector machined in the sleeve. This position corresponds to the coincidence of axes 10 and 10A.

When a reverse rotation of a few turns is carried out, the friction of the stabilizer 31 on the ground opposes this movement. The sleeve 2 therefore drives the pivot 3 to rotate, the key 6 coming into contact with the end face 23. This relative angular rotation takes place around the oblique axis 14 of the pivot 3 and with rotary sliding of the 8 faces and 9 one on top of the other. As a result of this rotation of angle R, the axes 10 and 10A are no longer merged but form an angle D:
D = 2 A sin R / 2

If for example we machine the housing 23, 24 to have R = 60 °, we obtain D = A

We see in the above formula that the deflection angle D of the fitting depends on the choice of the two variables A, the so-called pivot inclination angle, and R, the so-called pivot sector angle.

The two axes 10 and 10 A no longer being combined, the motion transmission shafts 40 and 41 contained and guided in the two sleeves 50 and 30 are no longer aligned; consequently the elbow fitting is located in line with a universal coupling 39 of the gimbal type for example which ensures the transmission of the torque from the motor element 50 to the tool 51 while allowing the relative inclinations of the two shafts 40 and 41 of the drive element and the pivot cartridge. In this configuration, the angle of the two sleeves therefore makes it possible, after orientation by conventional means, to execute the deflection operation.

It should be noted that volumetric motors of the Moineau type lend themselves particularly well to this type of connection, but its use can be extended without problem to turbine engines.

The deflection operation carried out and controlled, the simple resumption of direct rotation of the lining allows the resumption of the rectilinear drilling configuration under the appropriate conditions.

It appears that the device according to the invention makes it possible to combine in drilling the advantages of the use of an elbow fitting and those of the method in which rectilinear drilling results from the rotation of an eccentric stabilizer, and this without have the disadvantages. It also allows each of the two operations to be carried out in the configuration best suited to it.

It appears particularly advantageous in the case of the "correction" deviations previously mentioned.

Claims (7)

1 / Drill column for deviation drilling, this column having an axis at all points along its length and comprising
a rotary drilling tool (51) carried by a tool shaft (41) at the bottom of the column, this tool having a tool axis (10) which at the same time locally constitutes the axis of the column,
an active element (50) of a downhole motor (60) for driving this tool in rapid rotation relative to this column,
a pivoting element (30) of this same motor placed between this motor element and this tool and carrying said tool shaft to transmit to this tool an axial thrust applied to this column while allowing the rotation of this tool,
a controllable deflecting device which can take an angled configuration to locally bend the column in order to produce a curved drilling section, and which can take a rectilinear configuration to restore the rectilinearity of the column in order to produce a straight drilling section,
- and a succession of drilling tubes to transmit an axial thrust to said pivot element, and to allow the entire column to be driven in slow rotation, from the ground surface,
- Said deflector device comprising a lower sleeve (1) constituting a section of said drilling column above said tool, and having an axis (10) which is locally the axis of this column and which is integral with said tool axis (10),
- an upper sleeve (2) constituting a section of said drilling column above said lower sleeve, and having an axis (10A) which is locally the axis of this column,
- And pivoting means (3) connecting these two sleeves (1, 2), these means having a pivot axis (14) inclined at the same small angle (A) relative to the two axes (10, 10A) of these two sleeves and now these two sleeves relative to each other while allowing rotation of the lower sleeve (1) relative to the upper sleeve (2) about this pivot axis, an "alignment" position (24) of this lower sleeve ensuring the alignment of the axes (10, 10A) of these two sleeves, to put this device in its rectilinear configuration, a "deflection" position of this sleeve creating a deflection angle (D = 2 A sin R / 2) between the axes of these two sleeves to put the device in its bent configuration, these pivoting means leaving a free passage inside the column at least for a drilling mud,
- This column being characterized by the fact that said pivoting means (3) of the deflecting device allow only the lower sleeve (1) to rotate on a limited angular sector of pivoting (R) around said pivot axis, said alignment positions (24) and deflection (23) being defined by stops at the two ends of this sector,
- This column comprising, below the deflector device and above the tool (51), a member (31) rubbing against the wall of the well so that a rotary drive of this drilling column in a normal direction reveals a friction torque which brings the lower sleeve (1) into abutment at said alignment end (24) of the pivot sector, and so that a rotary drive of the drill string in the opposite direction causes a torque to appear friction which brings this sleeve into abutment at said deflection end, means being provided to maintain this sleeve at this deflection end in the absence of rotation of the column. 2 / drilling column according to claim 1, characterized in that said deflecting device is placed between said motor element (50) and said pivot element (30) and is axially traversed by a coupling (39) ensuring the transmission of movement of this motor to said tool shaft (41), this motor driving this coupling to rotate in said normal direction, so that the friction of this shaft in this pivoting element (30) tends to drive and maintain said lower sleeve (1 ) in abutment at said deflection end (23) in the absence of rotation of the drill string. 3 / Column according to claim 1, characterized in that said member rubbing against the wall of the well below the deflector device (1, 2, 3) and above the drilling tool (51) is a stabilizer (31 ) to keep the column in line with the well. 4 / Method of drilling wells with deviations, this method being characterized in that a column according to claim 1 is used,
- This drill string being driven in continuous rotation in said normal direction from the ground surface during rectilinear drilling steps to maintain said lower sleeve (1) in abutment at said alignment end (24) of the pivot sector (R),
- the transition from a straight drilling step to a curved drilling step comprising the following steps:
- temporary driving of the drilling column in rotation in said opposite direction from the ground surface to bring said lower sleeve into abutment at said deflection end (23) of the pivoting sector,
- And measurement of the angular position of the lower end of the drill string around its axis (10) and limited continuation of the rotational drive of this column in the opposite direction so that this axis arrives in a predetermined plane of curvature in which a section of curved well must be drilled,
said curved drilling step then taking place without rotation of the drill string,
- And the transition from a curved drilling step to a straight drilling step by resuming the rotation of the drilling column in the normal direction. 5 / A method according to claim 4, characterized in that, when passing to a curved drilling step, after said step of limited pursuit of the rotational driving of the drilling column in the opposite direction, there is provided a step column twisting during which the drilling column is rotated in the normal direction to prevent the elastic torsional torque which has appeared in the column subsequently causing the axis (10) of said lower sleeve to exceed said plane of curvature. 6 / Diverter device for drilling,
this device being intended to be inserted in a drilling column whose lower end carries a drilling tool (51) driven by a downhole motor (60) rotating around a tool axis
- This device comprising a lower sleeve (1) constituting a section of said drilling column above said tool, and having an axis (10) which is locally the axis of this column and which is integral with said tool axis (10),
- an upper sleeve (2) constituting a section of said drilling column above said lower sleeve, and having an axis (10A) which is locally the axis of this column,
- And pivoting means (3) connecting these two sleeves (1, 2), these means having a pivot axis (14) inclined at the same small angle (A) relative to the two axes (10, 10A) of these two sleeves and now these two sleeves relative to each other while allowing rotation of the lower sleeve (1) relative to the upper sleeve (2) about this pivot axis, an "alignment" position (24) of this lower sleeve ensuring the alignment of the axes (10, 10A) of these two sleeves to put this device in its rectilinear configuration, a "deflection" position of this sleeve creating a deflection angle (D = 2 A sin R / 2) between the axes of these two sleeves to put the device in its bent configuration, these pivoting means leaving a free passage inside the column at least for a drilling mud,
- This device being characterized by the fact that said pivoting means (3) allow only the lower sleeve (1) to rotate on a limited angular sector of pivoting (R) around said pivot axis, said alignment positions (24) and deflection (23) being defined by stops at the two ends of this sector. 7 / Device according to claim 6, characterized in that said pivot means are constituted by a pivot (3) of generally tubular shape elongated along said pivot axis (14), with a lateral surface constituting guide surfaces which are cylindrical of revolution around this axis and which cooperate with the inner surface of a housing formed in one (1) of said sleeves (1, 2) which constitutes a movable sleeve, to guide the rotation of this movable sleeve, this pivot also comprising a retaining shoulder (5) cooperating with an internal shoulder of this sleeve to prevent its axial displacement and to keep it in contact with the other of said sleeves, which is a fixed sleeve (2), this pivot further comprising retaining means (4) and angular locking means (6) to immobilize it in said fixed sleeve, this pivot or this movable sleeve finally comprising a projection (6) extending in a hollow angular sector (23, 24) formed in this movable sleeve or this pivot, respectively, to allow said rotation of the lower sleeve relative to the upper sleeve over a limited angular sector (R).

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