EP0201398A1 - Composition for oriented drilling - Google Patents

Abstract

The present invention relates to an assembly making it possible to drive a tool 206 in rotation about an axis 203 linked to said tool from a column 211, called the drive column, rotating at its lower end 201 around a second axis 202, said axes 201 and 202 being substantially concurrent at the same point A and forming between them the same angle α. This tool is characterized in that said assembly comprises in combination, a flexible joint incorporated in column 211, a remote-controlled deflector 208 adapted to create a deviation of angle α, means for controlling the value of said angle α, means of guide 223, 221, allowing the rotation of said tool 206 and said column 211 at its lower (flexible) end 201, around said axes 203 and 202, relative to said deflector 208 and means 12 for controlling the polar position of said deflector relative to said second axis.

Description

The present invention relates to an assembly for performing oriented drilling.

One of the objectives of the assembly according to the present invention is to make it possible, from existing or drilled vertical wells, to produce horizontal or inclined drains with precisely controlled orientation and connected to the vertical well by a section with a small radius of curvature (20 to 30 meters).

• -le forage horizontal (classique) utilisant les tiges de forage classiques implique des profils de transition de la section verticale à la section horizontale développés sur plusieurs centaines de mètres, -le forage à faible rayon de courbure utilisant des tiges épaisses articulées ne permet pas de contrôler efficacement et avec précision l'orientation du drain horizontal.

This objective cannot be achieved by any existing, operational or experimental system:

• -horizontal (conventional) drilling using conventional drilling rods involves transition profiles from the vertical section to the horizontal section developed over several hundred meters, -bore drilling with small radius of curvature using thick articulated rods does not allow effectively and precisely control the orientation of the horizontal drain.

The prior art can be illustrated by the following American patents US-A-2,198,016 and US-A-1,850,403, by the Belgian patent BE-A-865,955, by the German patent DE-A-3,306,405 as well as by the article entitled "Recent developments in unmanned drilling", published in the "Revue de l'Institut Français du Pétrole", Vol. 38, N. 1 from January-February 1983 at pages 63 to 81.

• a) pour la réalisation de drains horizontaux dans des réservoirs pétroliers peu profonds où le forage horizontal (classique) est inapplicable techniquement ou économiquement (nombreux gisements d'huiles lourdes et sables bitumineux);
• b) pour la réactivation de puits pétroliers existants anciens ne produisant plus par suite d'envahissement (eau ou gaz) ou d'épuisement relatif. L'intérêt de cette application, par rapport à la solution courante de forage de puits verticaux intermédiaires, augmente avec la profondeur des gisements;
• c) pour la réalisation de drains horizontaux dans la zone centrale à l'aplomb des plate- formes de forage-production en mer, où t'accès en forage horizontal (classique) n'est pas possible;
• d) pour l'augmentation du rythme d'exploitation de gisements à horizons multiples superposés en exploitant successivement les différents horizons par des drains horizontaux forés depuis un puits vertical unique;
• e) pour la réalisation de drains suivant les sinuosités de filons de minerais, minces et sensiblement horizontaux (lixiviation in situ - gazéification du charbon in situ).

The present invention can be used preferentially:

• a) for the realization of horizontal drains in shallow petroleum reservoirs where horizontal (conventional) drilling is technically or economically inapplicable (many heavy oil and oil sands deposits);
• b) for the reactivation of old existing oil wells no longer producing as a result of flooding (water or gas) or relative exhaustion. The interest of this application, compared to the current solution for drilling intermediate vertical wells, increases with the depth of the deposits;
• c) for the realization of horizontal drains in the central area directly above the drilling-production platforms at sea, where access by horizontal (conventional) drilling is not possible;
• d) for increasing the rate of exploitation of deposits with multiple superimposed horizons by successively exploiting the different horizons by horizontal drains drilled from a single vertical well;
• e) for the realization of drains according to the sinuosities of ore veins, thin and substantially horizontal (in situ leaching - gasification of coal in situ).

The present invention also makes it possible to drill multiple drains in several directions from a vertical well of common access.

To achieve these objectives, the present invention uses an assembly making it possible to drive a tool in rotation about an axis linked to said tool from a column, called a drive column, rotating at its lower end around a second axis, said axes being substantially concurrent at the same point A and forming an angle α between them.

This assembly is characterized in that it comprises in combination a deflector, or elbow, adapted to create a deviation of angle α, means for controlling the value of said angle a, guide means allowing the rotation of said tool and said column at its lower end around said axes relative to said deflector and means for controlling the polar position of said deflector relative to said second axis.

When this assembly is applied in the case of drilling from the surface, the means for controlling the polar position of said deflector may include a measurement probe integral with said deflector, said probe being marked angularly relative to the latter, a second column, said polar orientation column integral in orientation with said deflector rising to the surface, the lower part of said orientation column being flexible.

In the case where the deflector is remotely controlled electrically and the probe provides electrical signals, the polar orientation column may include in its center an electrical conductor adapted to transmit the measurement signals from the probe to the surface and the remote control signals from the surface to the deflector.

The drive column may have a flexible lower part, the lower end of which may be extended by a flexible extension and be fixed to said tool. The flexible part of said column may be coaxial and external to the flexible section of the polar orientation column.

The drive column and the polar orientation column may each comprise a substantially rigid part and these substantially rigid parts may be coaxial and connected to the surface, the substantially rigid part of the drive column may be connected, at the surface, to a rotating head.

The drive column can be connected to a downhole motor.

This downhole motor may be a multi-lobed helical volumetric motor whose rotary external body is connected to said drive column and whose non-rotating internal body is integral at its lower part with the flexible orientation column and at its upper part of the rigid upper part of the polar orientation column.

The flexible part of the drive column may have a perfectly smooth internal wall and an external wall provided with at least one rib wound in a helix.

The deflector may comprise two bodies articulated with respect to each other about an axis or a ball joint, the upper body forming an extension of the measurement probe and of the orientation column, the lower body supporting the pivoting of rotation of the drilling tool and means adapted to control the angle established between the two bodies.

The means for controlling the angle established between the two bodies may include a screw jack which governs the distance between a first point belonging to the lower body and a second point belonging to the upper body.

The measurement probe may be placed inside a centering module adapted to keep the longitudinal axis of the probe substantially parallel to the mean axis of the well at its level.

The measurement probe may be placed inside an internal centering body secured to the top of the base of the flexible orientation column and to the bottom of the upper body of the deflector.

The internal centering body can be placed coaxially inside an external centering body, which can itself be centered and aligned in the well by lower and upper centering shoes.

Said external centering body may be secured in the upper part of the foot of the main hose, and connected in the lower part to the drilling tool by a drive spacer assembly comprising a flexible rotary joint.

The centering and alignment of the internal centering body inside the external centering body and the centering of the drive spacer around the lower (s) and upper (s) body of the deflector may be ensured by at least three pivotings radial.

The longitudinal forces of thrust or traction between the main flexible and the drilling tool can be transmitted via the central core constituted by the internal centering body and the deflector and by two axial pivotings arranged respectively at the head and at the foot of this central core.

Appropriate conduits at the foot of the main hose, as well as flexible bellows insulation around the deflector, can ensure that between the head of the centering module and the tool, the circulation of drilling mud takes place only in the central part of the device, and that all the radial and axial pivots work in a clean environment lubricated by oil.

The assembly according to the present invention may include orientation means located on the surface at the upper end of said orientation column.

Thus, the present invention very often requires the use of a flexible lower column only over a length limited to the development of the horizontal drain and of the curved connection to the vertical section of the well.

The connection between the flexible lower column and the surface, through the vertical section of the well, can be carried out by conventional rigid drilling rods.

According to the present invention, it is possible to continuously measure, during drilling, directional parameters of the drain, at a very short distance behind the drilling tool.

According to the present invention, the possibility of placing immediately behind the drilling tool a device for controlling the tool, precise and with a large clearance, continuously remote controllable from the surface, allows perfect control of the trajectory of the tool, and thereby a good mastery of the profile of the well drilled.

• au forage sous équilibre de pression limite;
• aux venues de fluides sous pression;
• aux pertes de circulation;
• au collage différentiel;
• aux coincements.

In addition, the present invention makes it possible to cope safely, easily and essentially by the usual methods, with the potential difficulties inherent in all horizontal drilling, in particular:

• drilling under limit pressure equilibrium;
• the arrival of pressurized fluids;
• traffic losses;
• differential bonding;
• jamming.

Finally, the present invention allows the optimization of the transmission of thrust and torque from the vertical section of the packing to the drilling tool, through the flexible lower column.

• -la figure 1 compare le profil d'un puits foré suivant les techniques usuelles conventionnelles et le profil d'un puits foré suivant les techniques selon la présente invention, ces deux puits étant destinés à la mise en place d'un drain horizontal dans une même formation géologique,
• -la figure 2 montre en détail un mode de réalisation de l'ensemble selon la présente invention,
• -les figures 3 et 4 illustrent un mode d'entraînement de l'outil en rotation par une colonne rigide aboutissant en surface,
• -la figure 5 représente un exemple de mise en place du dispositif selon la présente invention,
• -la figure 6 représente un autre mode de réalisation selon la présente invention, et
• -la figure 7 montre schématiquement un mode simple de réalisation de la présente invention.

The present invention will be better understood and its advantages will appear more clearly on description which follows of a particular example, in no way limiting, illustrated by the appended figures, among which:

• FIG. 1 compares the profile of a well drilled according to conventional conventional techniques and the profile of a well drilled according to techniques according to the present invention, these two wells being intended for the installation of a horizontal drain in a same geological formation,
• FIG. 2 shows in detail an embodiment of the assembly according to the present invention,
• FIGS. 3 and 4 illustrate a mode of driving the tool in rotation by a rigid column ending at the surface,
• FIG. 5 represents an example of installation of the device according to the present invention,
• FIG. 6 represents another embodiment according to the present invention, and
• FIG. 7 schematically shows a simple embodiment of the present invention.

In FIG. 1, the reference 1 designates a geological formation in which a horizontal drain 2 must be drilled.

The present invention allows the control, at any time, of the radius of curvature of the trajectory of the drilled well and thereby has many advantages, as explained below.

In this figure, the distance L6 designates the distance separating the surface well 3 from plumb with the start of the horizontal drain 2 to be drilled in the case of the implementation of conventional conventional drilling techniques.

The distance LZ designates the same distance in the case of the implementation of the assembly according to the present invention.

It will be seen, unequivocally possible, that the distance L7 is much less than the distance L6 and that the surface well 5 used for the implementation of the assembly according to the present invention is practically vertical to the start of the horizontal drain.

Independently of this advantage, the present invention allows precise control of the trajectory of a borehole and makes it possible to rectify it almost instantaneously with a minimum of delay, this thanks to the control and control at all times of the positioning of the tool in the well. In addition, the present invention makes it possible to vary the radius of the curve of the trajectory of the drilled well by a large range.

After conventional drilling and casing of the vertical part of the well (or from the bottom of an existing well, by side strack) the curved, then horizontal drilling is carried out using a conventional tool driven in rotation and receiving a thrust from the vertical packing or column, via the flexible packing or lower column. The vertical packing may be rigid.

In FIG. 7, the reference 230 designates the well drilled, the reference 206 the drilling tool.

The lower end 201, of a drive column 211, rotates around an axis 202 _. and drives the tool 206 in rotation about an axis 203, by means of a flexible sleeve or flexible joint 204.

This flexible joint forms an extension of the drive column. The axes 202 and 203 are substantially concurrent at a point A and form between them a deflection angle a.

It is the deflector member 208 which makes it possible to produce the angle deviation α.

Guide means 221 and 223 allow the tool 206 and the lower part 201 of the drive column 211 to rotate respectively around the axes 203 and 202 relative to the deflector 208.

In the case of FIG. 7, the deflector is kept stationary in rotation thanks to a so-called orientation column 210.

In the example of FIG. 2, the reference 7 designates a deviation and measurement instrument. This instrument comprises a variable angle bend or deflector 8 located inside the lower end of a flexible joint 9 forming a flexible extension of the drive column, immediately behind the tool 6; the radial or polar orientation of this elbow 8 is controlled by a flexible polar orientation column 10 at least on its lower part. This column is substantially coaxial with the flexible joint 9, itself connected to a main drive hose 11, possibly extended to the surface by a rigid extension.

The assembly comprising the flexible joint, the main drive hose and the rigid extension constitute a column for driving the tool in rotation, likewise, the assembly comprising the flexible joint and the main drive hose for - will be qualified as a flexible part of the drive column. However, in this case, when reference is made to the axis around which the lower end of the drive column rotates, it is the axis of the lower end of the main hose.

The bend or deflector 8 makes it possible to print radial deviations from the tool 6 in determined controllable directions, resulting in different degrees of curvature, or in straightness, of the well profile and in controlling its azimuth.

The instrument 7 also includes a directional measurement probe 12 housed in the center of the orientation column, immediately behind the deflector 8 (or approximately 2 to 3 meters behind the tool).

It makes it possible to measure, at a short distance behind any drain section that has just been drilled, the inclination and the azimuth of this section.

This speed of response makes it possible to correct the profile if necessary without delay, by acting on the angle and on the orientation of the deflector 8. This rapid looping between the creation of the hole 13, the measurement of its profile, and the reaction on the deflector 8, constitute one of the major innovations of the system compared to the other known horizontal drilling systems. It is he who opens the possibility of producing profiles with small radii of curvature, possibly complex, and yet with precision, either to faithfully execute a determined profile, or to follow, upon discovery, the practical profile of a given layer. .

The precision of the directional measurement implies a satisfactory centering of the measurement probe 12 in the hole, as well as a certain smoothing of unduly short and insignificant undulations of the latter. To this end, the probe 12 is aligned in a rigid extension 14 of the orientation column 10, this extension which can be described as an internal centered body is itself centered in a module or centralizing body and external stabilizer 15 of length 3 to 4 meters, inserted between the main hose 11 and the deflector module 8.

This external centering body 15 may include lower 115 and upper 116 centering shoes.

In addition to the inclination and the azimuth of the profile of the drain, the probe 12 can measure the radial or polar orientation of the deflector with respect to the high generatrix of the hole or with respect to magnetic north (in Anglo-Saxon term " tool face "), to allow this radial orientation to be maintained or corrected, by surface action on the orientation column.

The probe 12 may include magnetometers for measuring the azimuth and the "tool face". These magnetometers must be distant from significant magnetic masses: for this purpose, the centering module 15 and the rigid extension 14 of the orientation column may be made of non-magnetic metal.

• Une solution technologique proposée et représentée sur la Fig. 2 comporte l'utilisation d'une genouillère articulée 16 dont la flexion ou déviation est contrôlée par un vérin électrique fortement démultiplié 17 : ce fait, combiné au court bras de levier du déflecteur, entraîne que le couple nécessaire au moteur du vérin pour vaincre les efforts de déflection est faible et la puissance nécessaire au moteur est également faible, et peut être de l'ordre de 1/4 de kW.

Different embodiments of the deflector 8 are possible:

• A technological solution proposed and shown in FIG. 2 includes the use of an articulated toggle joint 16, the flexion or deflection of which is controlled by a greatly increased electric actuator 17: this fact, combined with the short lever arm of the deflector, causes the torque necessary for the actuator motor to overcome the deflection forces is low and the power required for the motor is also low, and can be of the order of 1/4 kW.

An electric cable which can be a single conductor 18; located in the center of the orientation column 10 and its extension to the surface transmits the electrical power and the remote controls to the deflector 8 (discontinuous actions) and ascends, in digital mode, the signals from the measurement probe 12 directional for decoding and surface treatment - (continuous transmission). It is well known to those skilled in the art to carry out transfers of electrical power and electrical signals from a single conductor.

The supply of drilling mud for irrigation of the tool 6, washing of the hole and balancing of the formation pressures takes place through the annular space between the external wall of the orientation column 10 and the internal wall of the main hose. 11 ': thus the friction between these walls, during the rotation of the main hose 11 around the orientation column 10 is lubricated friction.

Just upstream of the centering module 15, the flow of mud is directed towards the center, inside the column extender, through orifices 19 and thus channeled to the center of the tool 6. The annular space 20 around the column extension and the deflector 8 is filled with oil which can be in equipression with mud this thanks to devices well known to those skilled in the art. This oil provides efficient lubrication of the centering bearings 21 22 and 23 and of the upstream axial stops 24 and downstream 25.

Rotating seals 26 and 27 upstream and downstream isolate the oil from the mud. A semi-rigid metallic membrane 28 connects the upstream 29 and downstream 30 elements of the toggle 16 around the deflector 8; this membrane may be formed by a metal bellows. A flexible joint 9, resistant to the pressure differential between its internal face and its external face (equal to the pressure drop in the tool), connects the centering module 15 to the tool-holder endpiece 32.

The thrust transmission from the main hose 11 to the tool-holder endpiece 32 can preferably be done through the extension of the orientation column 14 and the deflector 8 via the upstream axial stops 24 and downstream 25. Thus the joint flexible 9 will not have to support this thrust, It however supports rotation. torque, and flexion combined. generators of fatigue effects: consequently, this flexible joint 9 can be considered as a wearing part which it is allowed to replace periodically. Of course, the axial stop 24 may be placed substantially in the vicinity of the radial stop 22. In this case the transmission of the axial thrust to the tool will be done via the centering module 15 instead of being done via the extension 14 of the orientation column.

The main hose 11 has, among other functions, that of transmitting to the tool 6 rotation, cutting, and axial thrust and of conveying the drilling mud towards the bottom. It must allow the ascent of the mud and the cuttings in the ring finger of the hole.

This main hose will preferably be designed to minimize the risks of differential bonding, it will have to resist the traction necessary to extract the lining from the drain with the possible help of rotation and circulation combined in case of jamming and finally it will preferably be easily storable and transportable on the surface.

• -un tube interne en plastique,
• -une carcasse en fil d'acier agrafé à profil "Zeta",
• -une gaine plastique intermédiaire,
• -deux nappes croisées d'armures d'acier au pas d'environ 45,, et
• -une gaine externe en plastique (Rilsan).

It may be made up of a (conventional) structure existing on the market and marketed by the COFLEXIP Company. Such structures generally include:

• -an internal plastic tube,
• -a carcass in stapled steel wire with "Zeta" profile,
• -an intermediate plastic sheath,
• -two crossed plies of steel armor with a pitch of about 45 ,, and
• -an external plastic sheath (Rilsan).

Following a particular embodiment of the main hose 11, according to the present invention, it may include a spiral outer rib 33 of polyamide loaded with reinforcing fibers - (aramid fibers, for example the fiber designated by "Kevlar" Dupont de Nemours), located on its outskirts.

• -son diamètre externe étant proche de celui du trou (et du dernier tubage ou d'un tubage ou liner guide temporaire dans la section verticale du puits), elle assure le guidage du flexible 11 et évite son flambage en compression lorsqu'il transmet la poussée à l'outil;
• -par effet de vissage dans le trou et dans la boue - (analogue à celui d'une tarière), elle aide à la transmission de la poussée venant du lest présent dans la portion verticale du puits et elle génère elle-même une certaine poussée additionnelle;
• -cet effet facilite aussi l'évacuation des déblais en évitant leur sédimentation sur les génératrices basses du trou et en induisant leur translation vers la surface;
• -elle contribue également à maintenir le trou "ouvert" par son action continue d'alésage,
• -enfin, la nervure isole le flexible proprement dit du trou. Elle évite ainsi les risques de collage différentiel et les risques de détérioration de la gaine externe du flexible 11 par abrasion ou accrochages,
• -par contre, étant en contact de frottement permanent avec les parois de trou et de tubage, et malgré sa constitution en polyamide chargé de fibres d'aramide (anti-usure et à faible frottement), cette nervure aura une durée de vie plus courte que celle du flexible proprement dit : elle devra donc pouvoir être remplacée ou rechargée périodiquement.

This rib 33, with an essential role, fulfills multiple functions:

• its external diameter being close to that of the hole (and of the last casing or of a casing or temporary guide liner in the vertical section of the well), it guides the hose 11 and prevents it from buckling in compression when it transmits the tool thrust;
• - by screwing effect in the hole and in the mud - (similar to that of an auger), it helps the transmission of the push coming from the ballast present in the vertical portion of the well and it generates itself a certain push additional;
• this effect also facilitates the evacuation of the cuttings by avoiding their sedimentation on the low generators of the hole and by inducing their translation towards the surface;
• -it also helps to keep the hole "open" by its continuous boring action,
• - finally, the rib isolates the actual hose from the hole. It thus avoids the risks of differential bonding and the risks of deterioration of the external sheath of the flexible 11 by abrasion or snagging,
• -on the other hand, being in permanent friction contact with the walls of the hole and casing, and despite its constitution in polyamide loaded with aramid fibers (anti-wear and low friction), this rib will have a shorter lifespan than that of the hose itself: it should therefore be able to be replaced or recharged periodically.

The only function of the flexible column 10 is to transmit the orientation torque from the surface to the deflector 8 and to maintain this orientation during drilling. Its diametrical dimensions must spare, in its center, the passage of the electrical transmission cable 18 and, externally, an annular 34 sufficient in the main hose 11 for the passage of the downward flow of the drilling mud, indicated by the arrow 35.

It could be constituted by a conventional and simple structure of the type of that marketed by the Company COFLEXIP. It may include, in particular, an internal carcass of stapled metal strip, two crossed layers of steel armor with relatively short pitch - (optimization of the torque resistance), and an external envelope.

This hose 10, permanently installed inside the main hose 11 will nevertheless be easily removable for inspection, maintenance and to allow, if necessary, access to the interior of the main hose 11 during operations (for example for unscrewing with explosive, in Anglo-Saxon terms "back-off", above the background instrument).

It will be noted that the friction resulting from the rotation of the main hose around the stationary orientation hose is that of plastic material (such as the material sold under the brand rilsan) on itself, with the interposition of the descending drilling mud, not or little loaded with solids. These frictions, and the wear of the surfaces, are therefore low.

The electrical transmission cable 18, possibly a single conductor, can be permanently installed in the center of the orientation hose.

In the lower part, it is connected to the measurement probe 12, during the assembly of the main flexible assembly 11 - orientation hose 10 on the bottom instrument 7. In the upper part, it ends with a connector 36, possibly a single contact, housed in the center of the combined end piece of main hose 11 and orientation hose 10. The connection of cable 18 to probe 12 can be achieved by a connector 37.

Regarding the column connection in the lining of the vertical section of the well, two lining systems can be considered depending on the embodiment of the rotation in drilling. These two embodiments are shown in FIGS. 3, 4 and 6.

If the movement intended to drive the tool comes from the surface (Figs. 3 and 4) (this mode is commonly called rotary drilling), the main hose 11 is extended to the surface by a main train 38 ,, optionally rigid, possibly consisting of drill rods 39 and conventional drill rods 40. The flexible orientation 10 can be extended at the center of the main landing gear 38 by an orientation column 41, possibly rigid, consisting of rods conventional drilling type mining constant external diameter, commonly called "flush mining rod" by those skilled in the art.

The assembly comprising the orientation hose and the possibly rigid column constitutes the polar orientation column or more simply the orientation column.

The rotation, and the injection of drilling mud, are ensured by a conventional motorized head 42 (in English terms "Power Swivel") connected to the main gear 38. In its center passes and extends the rigid column of orientation 41 and 10, the top of which is connected to an orienter 43 of the orientation column, mounted on the frame of the motorized head 42.

The assembly of the gasket described above at the start of drilling the drain can be carried out as indicated below.

The tool and bottom instrument assembly having been pre-assembled is placed on corners.

The main flexible assembly 11 - flexible orientation 10 - central cable 18, is connected to the bottom instrument 7 and then lowered, by unwinding from the storage drum 44 - (FIG. 5) of the flexible assembly, up to to be installed on the corners of the upper combined nozzle.

The drill rod (s) 39 and main rods 40 are then successively connected and descended, until the tool is brought close to the start of drilling dimension of the drain (vertical hole bottom in the case of a "new" well ; lateral opening pre-executed in the production casing, in the case of wells "taken up"). The last added drill rod 45 (at the top of the train) is placed on corners 46, 47, its top projecting, above the corners, for example, from 0.3 to 0.4 meters.

The flexible orientation column 10 is then extended to the surface by introduction, screwing, and successive descent of sections of mining rods with constant external diameter, commonly called mining rod "flush" by the skilled person, and constituting the column upper orientation 41 (fitting for connections on a wedge box installed on the top of the upper main rod).

The latest addition of orientation rod 48 is accompanied by the connection of the foot of the upper orientation column 41 to the top of the orientation hose 10 by means of a simple fitting nozzle with square or hexagonal section, at reference 49. The length of the last added rod is such that its top exceeds that of the upper main rod, for example from 0.3 to 0.6 meters.

The extension 50 of the electric cable is then introduced into the center of the column and lowered by unwinding: a possibly single-contact plug 36, at its foot, ballasted with a load bar, is connected, for example, by simple fitting, at the end of the descent , on the head plug of the flexible assembly The total length of the cable may, depending on the depth of the well, be made up of several sub-sections, and may have a significant excess length compared to the length of the rigid train.

This extra length is housed by sinusoidal 51 in the lower part of the upper orientation column 41, without risk of deterioration by erosion since the mud circulation is external to this orientation column. It will be noted that, for the same reason, the problems of electrical insulation, in particular with connections by single-contact plugs, are greatly facilitated.

At its upper part, the cable extension ends with a plug, possibly a single contact, 52 which comes to rest in a support end piece at the top of the upper rod of the orientation column.

The start of drilling, then its deepening, takes place according to the same procedure, using "add-on elements" 53 constituted by matched lengthwise sections of drill rods 54 and mining rods 55, the latter being equipped lengths of extension electric cable 56, permanently mounted and terminated at each end by possibly single-contact plugs 57 and 58 anchored at the ends of the mining rod 55.

A set of two paired sections of main rods 54 and orientation 55 is prepared in the rat hole (in English term "rat hole"), the bottom of the latter being arranged so that the mining rod 55 is offset, upwards, relative to the main rod, for example 0.2 meters.

The motorized injection head 59 (in Anglo-Saxon terms "power swivel"), with its screwing tip on the rods and driving the drill train in rotation, is provided with an upper column extension 60 orientation 41, entered in the orienter 43 of "tool face", analogous to a small caliber hydraulic wrench. The orienter 43 is supported by a jack 61 with vertical clearance which can be approximately 0.5 meters, itself anchored on the frame of the motorized head 42. A cable gland 62 with hydraulic control (of the lubricator type "snubbing" "), above the" power swivel ", allows sealing on the upper extension (outside polished chrome) of the orientation column.

The upper extension 60 of the orientation column is permanently fitted with the upper extension of the electric cable, terminated in the lower part by a single-contact plug, and in the upper part by a rotary contact 65. Above this rotary contact, the cable surface follows the mud injection hose, and is connected to the equipment for receiving surface measurements and the deflector's remote control.

Thus equipped, the motorized injection head attached to the movable block by elevator arms 63 and 64 qualified as "long links" in terms of angle-Saxons, is ready for maneuvering.

The upper extension 60 of the orientation column is positioned to protrude under the nozzle of the injection head, for example 0.1 meter, while the support cylinder is in the middle position. The injection head 42 is brought to the vertical of the rat hole and positioned using the muffle to locate the foot of the upper extension 60 of the orientation column above the mining rod 55, for example at 10- 15 cm.

The upper extension 60 is then approached then engaged and screwed onto the mining rod 55 by combining the rotation of the orienter 43 and the translation of its support cylinder 61, which allows a fine approach and avoids the risks of deterioration of the mining rod threads 55. The electrical cable connection 56 is established simultaneously. The bio-cage is made at the maximum admissible torque for threading, a torque which can be automatically measured by the guide 43 or applied by keys.

The jaws of the orienter 43 are then loosened and separated from the upper extension 60 of the orientation column. The injection head 42 is lowered using the muffle and the nozzle of the injection head is engaged and screwed onto the main rod 54 by rotation of the head. Locking can be completed with conventional keys.

The support cylinder 61 is put in the high position.

The orienting jaws 43 are tightened on the upper extension 60.

The set of addition rods 53 thus connected to the injection head is extracted from the rat hole and brought with the aid of the muffle above the drilling train 38 on standby on corners 46, 47, maintaining a space between main rod 45 on corners and main adding rod 54, this space may be approximately 0.5 meters.

The upper extension 60 of the orientation column 41 is lowered and approached then connected to the orientation column on standby in the drilling train 38 by actions of the orienter 43 and its support jack 61.

The orienting jaws are loosened, and the main adding rod 53 is approached and connected to the main landing gear 38 on corners 46, 47 by actions of the muffle and of the injection head, the blocking can be completed by the keys .

The support cylinder 61 is positioned for setting the orientation column 41 under tension under its own weight (slight sliding possible of the sliding fitting at the foot of the column).

The cable gland 62 is closed on the upper orientation extender.

Drilling can begin.

The procedures for disconnection of the motorized injection head 42 at the end of the first drilling pass and for the following additions use the same principles, reversed for disconnections, as those described above. The same applies to the extractions of the addition rods 53 during the ascent and exit from the hole.

It will be noted that each addition 53 can be made by sections of 2 or 3 rods of 9 meters, or by 27 meters: there will therefore be 11 to 18 additions to operate for a drain of 300 to 500 meters.

According to another embodiment, the movement for driving the tool comes from a downhole motor (see FIG. 6).

The main hose 11 is rotated by a downhole motor 66, preferably of the volumetric type connected at the head of the flexible train 11. This motor 66 is used in the inverted position relative to the conventional mode: it is the external body 67, normally stator, which is connected to the main flexible 11 and which becomes the rotor or rotating element.

The central shaft 68, with lobes, becomes stator: the end piece 70, normally a tool holder, of this central shaft 68 is in the upper position, and connected to the drill set 69 and conventional stems rising to the surface .

The other, normally free, end 71 of the central shaft 68 is connected to the orientation hose 72: the latter can therefore be oriented by action on the upper rod train 73 which, apart from the orientation movements, remains stationary angularly. The central shaft 68 of the downhole motor as well as its extension in its pivoting and its precession gimbals may be arranged to provide a central passage in which is housed an extension 75 of the electrical transmission cable 74. This passage may be cylindrical and have a diameter of about 1/2 ".

Above the downhole motor 66 and this electric extender, the electrical connection to the surface is formed by an optionally monoconductive cable 77, connected in the lower part to the extender 75 in the engine, by an optionally monocontact plug which can be ballasted with a load bar.

• Il peut être unique ou continu, type câble de diagraphie, en terme anglo-saxon "wire line", introduit au travers d'un raccord à sortie latérale 78, permettant les ajouts de tiges 79 sans manoeuvre de câble.

This cable can be made in several ways:

• It can be single or continuous, logging cable type, in Anglo-Saxon term "wire line", introduced through a connector with lateral outlet 78, allowing the addition of rods 79 without cable operation.

It may include a first section of cable of ad-hoc length, introduced in the center of the assembled rods when the tool is near the bottom of the hole before drilling begins, plus a complement of cable "wire line" in the center rods, connected to the previous one by possibly single contact plug surmounted by a load bar, and exiting at the head of the rod train through a cable gland, this additional cable therefore having to be operated during each addition. Thus, for example, for a length of the drain of between 300 and 500 meters, the cable will have to be maneuvered 11 to 18 times in total if the additions are made in triplicate, using an injection head. Instead of the cable supplement, it is possible to use rod elements grouped in groups of three for additions, each group being fitted with a central cable with end plugs, possibly single contact, permanently installed.

Of course, it will not depart from the scope of the present invention if each rod element is equipped with a central cable with plug.

The embodiment of the invention according to which the movement for driving the drilling tool is of the rotary type has certain advantages which are given in the remainder of this text relative to the embodiment comprising a downhole motor.

The rotary drilling embodiment has great flexibility in adapting rotation speeds and torques to terrain and drilling conditions. There is no limitation in maximum torques other than that imposed by the resistance limits of the rods. So the capacity to fight against conditions of jamming or intense friction is high.

Such an embodiment allows complete independence of the mechanical parameters of the drilling and of the mud flow rates and pressures.

The entire electrical connection between the bottom and the surface is done without mud which, according to the embodiment described as rotary drilling, facilitates the obtaining and maintenance of good electrical insulation at the connections and eliminates the problems of Erosion and deterioration of cables in the mud flow.

The rotary embodiment avoids the problems linked to the cable placed in the annular of a well or to frequent cable maneuvers.

According to this embodiment, all the components of the system, apart from a few simple adaptations which, however, use known elements on the injection head, are entirely conventional.

The embodiment according to the present invention qualified as rotary drilling allows, if necessary, in particular in the case of jamming impossible to solve by rotation-traction-circulation, to completely extract the central orientation column, including the flexible part, at the same time as the electric cable and the measuring probe, thus freeing the center of the main landing gear to the deflector and allowing the execution of an unscrewing with explosives and the possible recovery of most of the undercarriage, including all or part of the main hose, depending on the level of jamming.

Finally, this embodiment makes it possible, in the event of loss of circulation, to inject sticky products.

However, this embodiment has drawbacks relative to the downhole engine version which resides in particular in the relative complexity of the composition of the rigid drilling train as a whole and of its implementation. This is to be tempered, however, in consideration of the simplicity, classicism, and robustness of the individual components of this drill string.

The embodiment according to the present invention, which includes a downhole motor, has advantages relative to the so-called rotary version including, in particular, that of the simplicity of the composition of the rigid drilling train, and of its implementation.

However, this background engine embodiment has limitations, some of which are listed in the remainder of this text.

Thus, the maximum torque that can be supplied by the downhole motor is necessarily limited. For example, with 9 lobe motors. currently available on the market, you can only count on 400 to 500 mkg.

The above comparison leads to prefer the rotary mode when one has the choice.

Claims (16)

1. -Assembly for driving a tool in rotation about an axis linked to said tool from a column, called drive column, rotating at its lower end around a second axis, said axes being substantially concurrent at the same point A and form between them the same angle a, characterized in that it comprises in combination a remote-controlled deflector (208) adapted to create a deflection of angle a, control means - (16, 17) of the value of said angle a, guide means (223, 221, 25, 23, 22, 21, 24) allowing the rotation of said tool (6) and of said column at its lower end (201) around said axes (203, 202) relative to said deflector (208) and means (12) for controlling the polar position of said deflector relative to said second axis. 2. -An assembly according to claim 1, applied in the case of a drilling carried out from the surface, characterized in that the means for controlling the polar position of said deflector comprise a measurement probe (12) integral with said deflector, said probe being identified angularly relative thereto, a second column (10) said polar orientation column integral in orientation with said deflector and rising to the surface, the lower part of said orientation column being flexible. 3. -An assembly according to claim 2, applied in the case where the deflector is remote controlled electrically and where the probe provides electrical signals, characterized in that said polar orientation column (10) has in its center an electrical conductor (18) suitable for transmitting the measurement signals from the probe to the surface and the remote control signals from the surface to the deflector. 4. -An assembly according to claim 2, characterized in that the drive column comprises a flexible lower part (11) whose lower end is extended by a flexible extension fixed to said tool (6) and in that said flexible part of said column is coaxial and external to the flexible section of the polar orientation column (10). 5. -An assembly according to claim 4, characterized in that said drive column (11) and said polar orientation column (10) each comprise a substantially rigid part and in that said rigid parts are coaxial and connected on the surface, the rigid part of the first column being connected, on the surface, to a rotary head (42). 6. -An assembly according to claim 2, characterized in that said drive column (11) is connected to a downhole motor (66). 7. -An assembly according to claim 6, characterized in that said bottom motor (66) is a multi-lobed helical volumetric motor whose rotary external body (67) is connected to said drive column (11) and whose internal body (68) non-rotating is integral in its lower part with the flexible orientation column (72) and in its upper part with the rigid upper part (69, 70), with the polar orientation column. 8. -An assembly according to claim 4, characterized in that the flexible part of said drive column (11) has a perfectly smooth inner wall and an outer wall provided with at least one rib (33) wound helically. 9. - assembly according to claim 2, characterized in that said deflector (8) comprises two bodies (29, 30) articulated relative to each other about an axis or a ball joint (16), the upper body - (29) forming an extension of the measurement probe (12) and of the orientation column (10), the lower body (30) supporting the pivoting point (23 and 25) for rotation of the drilling tool (6) and means (17) adapted to control the angle established between the two bodies. 10. -An assembly according to claim 9, characterized in that said means for controlling the angle established between the two bodies comprise a screw jack (17) which governs the distance between a first point belonging to the lower body and a second point belonging to the upper body. 11. -An assembly according to claim 3, characterized in that the measurement probe (15) is placed inside a centering module (14) adapted to maintain the longitudinal axis of the probe substantially parallel to the axis way from the well to its level. 12. -An assembly according to claim 11, characterized in that the measurement probe is placed inside an internal centering body (14) secured towards the top of the base of the flexible orientation column (10) and downwards from the upper body (29) of the deflector (8), in that said internal centering body (14) is centered inside an external centering body (15), which is centered and aligned in the well by lower and upper centering shoes (115 and 116), said external centering body (15) being secured in the upper part of the foot of the main hose (11), and connected in the lower part to the drilling tool (6) by a drive spacer assembly comprising a flexible rotary joint (9). 13. -An assembly according to claim 11, characterized in that the centering and alignment of the internal centering body (14) inside the external centering body (15) and the centering of the drive spacer around the bodies lower (30) and upper (29) of the deflector (8) are provided by at least three radial pivots (23, 22, 21). 14. -An assembly according to claim 11, characterized in that the longitudinal forces of thrust or traction between the main hose - (11) and the drilling tool (6) are transmitted through the central core constituted by the internal centering body (14), the deflector (8) and two axial pivotings (25, 24) at the head and at the foot of this central core. 15. -Assembly according to claims 13 and 14, characterized in that appropriate conduits at the foot of the main hose and a flexible bellows insulation (28) around the deflector ensure that between the heads of the centering module and the tool , the circulation of the drilling mud takes place only in the central part of the device, and that all the radial and axial pivotings (21, 22, 23, 24 and 25) work in a clean environment (20) lubricated by l 'oil. 16. -An assembly according to claim 2, characterized in that it comprises orientation means - (43) on the surface of said orientation column.

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