EP3757349B1 - Maintenance device and method for determining the position of a locking point for a tubular element - Google Patents

Description

The invention relates to the field of the exploitation of the subsoil such as mining and oil exploitation, and more particularly the field of drilling. The invention relates to a maintenance device for determining the position of a locking point of a tubular element, preferably in a borehole. The invention also relates to a method for determining the position of a locking point of a tubular element in a borehole.

[Prior art]

Drilling has been used for years to dig holes in the earth. Generally, drilling refers to all the techniques used to dig or drill the earth to great depths, as well as the result of their application. Historically, drilling made it possible to find and exploit resources such as water. Then over the years, drilling techniques have developed with the exploitation of other resources such as oil and gas. New fields of application using drilling techniques have also appeared, such as the field of geothermal energy, geotechnics, the environment and also scientific research.

In general, drilling consists of digging with the aid of a rotating drill bit placed at the end of a tubular element such as a tubular column or drill string through layers of earth and rock. As drilling progresses, drill tubes are used to advance the borehole deeper. However, as the drilling progresses, it is not uncommon for the drill pipe to get stuck, in particular due to landslides, putting an end to the drilling operations.

Due to the length of the tube, the difficulty of access and clearance, it is difficult or even impractical to proceed with the clearance of the blocked section(s).

In order to achieve clearance, it is common practice to unscrew ("back-off" in Anglo-Saxon terminology) or cut the drill string at a specific location to recover a maximum of drill rods and equipment for further use, or yet to drop the drill string at the stall point. These solutions are fraught with consequences, time-consuming, costly, jeopardizing the safety of the operators and the stability of the drilling. It is therefore necessary to know precisely the blocking point of a drill pipe in order to limit these consequences.

Current techniques, developed by oil groups, are based on a tool commonly called FPI (“Free Point Indicator” in Anglo-Saxon terminology). This tool makes it possible to determine the place where the drill pipe is blocked in order to be able to subsequently free it, for example by means of explosives. For this, the tool is removably fixed to the internal walls of the drill pipe which is subjected to a tensile or torsion stress. The FPI measures deformations which make it possible to estimate the locking point of the drill pipe. However, this tool only measures a few meters each time, requiring a large number of measurements to be taken to cover the entire tube. In addition, the descent protocol is long, possibly extending over several hours, to determine the blocked portion. Moreover, this technology is particularly expensive and fragile because of the electronics and the on-board mechanical systems.

Another system called HFPT (“Halliburton Free Point Tool” in English terminology) also makes it possible to determine the position of a blocking point in a borehole. For this, this tool measures a reference magnetic value and a magnetic value after the exertion of a stress on the drill pipe and then a comparison of these measurements is made. However, this system also requires complex electrical equipment. Another technique based on magnetic sensors consists of marking magnetic markers in the casing which are subsequently read by the magnetic sensors during the retrieval of the drilling system. This technique requires specific and expensive equipment. Such a method is for example illustrated in the document US2008060808 .

Techniques using acoustic sensors have also been implemented. For this, and as described in the document US7660197 , transmitters configured to generate and receive acoustic waves were used. Depending on the speed and direction of propagation of the acoustic waves, it seems possible to determine a stress in the drill pipe. However, these techniques determining a stress do not make it possible to demonstrate in a reliable and precise manner the position of the blocking point of a tube. In addition, several sensors are necessary, leading to an additional cost of use and a total immobilization of the borehole for an often excessive time. By example, according to the document US7389183 , acoustic data and magnetic permeability data on a stressed or unstressed tube are compared to determine the nature and location of the blockage. These techniques require carrying out several measurements, both acoustic and magnetic, on the one hand in the presence of a constraint, and on the other hand without constraint. In addition, the data collected must be analyzed and compared with each other, which further increases the time of use and the complexity of the system. Furthermore, these techniques prove to be time-consuming and expensive due to the plurality of sensors and the equipment required. In addition, they require significant downtime of the borehole.

Other techniques using optical fibers have also been developed. For example, a first fiber can be wrapped around the upper end of the tube and a second fiber is then wrapped around the lower end of the tube, then a twist is applied and measured. This technique requires descending the tube little by little and taking spot measurements along the tube. In addition, explosives are also required to free the rod when it is stuck ( CN106351646 ). However, these techniques are just as time-consuming, require several measurements and point-to-point measurements. They do not make it possible to reliably and precisely highlight the position of a blocking point of a tube. In addition, they are not safe for operators and require downtime of the drilling.

Thus, there is a need for new systems and new methods for determining a blocking point of a tubular element in a borehole capable of responding to the problems generated by the existing methods.

[Technical problem]

The object of the invention is therefore to remedy the drawbacks of the prior art. In particular, the object of the invention is to propose a maintenance device for determining the position of a blocking point of a tubular element. This device being suitable for use in a borehole, inexpensive in particular thanks to a short period of immobilization of the borehole for example, and being able to be lowered quickly into the borehole. In addition, the device makes it possible to check in a single measurement several tens of meters, preferably a hundred meters.

The invention also aims to provide a method for determining the position of a blocking point of a tubular element by means of a maintenance device, said method being quick and simple to implement, with a reduced number of measurements, and making it possible to control costs in particular, thanks to the reduction in the downtime of the drilling rig and the personnel involved.

[Brief description of the invention]

To this end, the invention relates to a maintenance device for determining the position of a blocking point of a tubular element characterized in that it comprises a fiber optic cable and a plurality of holding guides, each retaining guide being fixed to the fiber optic cable and comprising a means of attachment to an internal wall of the tubular element. The implementation of a fiber optic cable makes it possible to have a completely passive device and therefore no electrical system is lowered into the borehole. This improves the safety of operators, installations and drilling. In addition, the optical fiber cable allows in particular, thanks to the optical fiber, an easy measurement of the deformation. The measurements are of increased accuracy, precision and reliability.

The retaining guides make it possible to secure the fiber optic cable to the drill pipe to the internal walls of the drill pipe.

• il comporte un câble de sécurité et chaque guide de maintien est agencé de façon à permettre un mouvement de translation des guides de maintien par rapport au câble de sécurité. Cette caractéristique permet d'augmenter la robustesse du dispositif de maintenance. En outre, ceci permet un degré de liberté entre le câble de sécurité et les guides de maintien, se traduisant par un coulissement du câble de sécurité à l'intérieur de chaque guide de maintien. Ce degré de liberté permet de libérer le câble à fibre optique lors de la mesure.
• il comporte une pluralité de butées, chaque butée étant couplée au câble de sécurité et à un des guides de maintien de façon à limiter le mouvement dudit guide de maintien par rapport au câble de sécurité. Ceci permet d'augmenter et d'améliorer la sécurité du dispositif de maintenance, aussi bien durant la descente dans l'élément tubulaire du dispositif de maintenance que lors de la remontée. Les butées permettent d'améliorer la protection et la sécurité en constituant une protection du câble à fibre optique en évitant qu'une force de traction trop importante lui soit imposée.

• il comporte une pluralité de paires de butées, chaque butée d'une paire de butées étant couplée au câble de sécurité et étant positionnée respectivement de part et d'autre d'un des guides de maintien de façon à limiter le mouvement dudit guide de maintien par rapport au câble de sécurité. La pluralité de paires de butées permet de limiter le mouvement de chaque guide de maintien par rapport au câble de sécurité. Ceci permet également, d'augmenter et d'améliorer la sécurité du dispositif de maintenance, aussi bien durant la descente dans l'élément tubulaire du dispositif de maintenance que lors de la remontée. Les butées permettent d'améliorer la protection et la sécurité en constituant une protection du câble à fibre optique en évitant qu'une force de traction trop importante lui soit imposée.
• le moyen d'accroche est sélectionné parmi : un moyen d'accroche mécanique, un moyen d'accroche magnétique, un moyen d'accroche électromagnétique, un moyen d'accroche chimique, de préférence un moyen d'accroche adhésif. Le moyen d'accroche permet de fixer indirectement le câble à fibre optique à l'élément tubulaire et plus précisément à une paroi interne de l'élément tubulaire.
• les moyens d'accroche des guides de maintien permettent une fixation fixe et amovible à la paroi interne de l'élément tubulaire. Une fixation fixe permet tant qu'elle est active d'empêcher tout mouvement d'un guide de maintien par rapport à l'élément tubulaire. Par contre la fixation est amovible donc le guide de maintien peut être détaché.
• les guides de maintien comprennent des aimants et un système de serrage. Les aimants permettent d'assurer la fixation des guides de maintien avec l'élément tubulaire. Le système de serrage permet de retenir le câble à fibre optique sur les guides de maintien. Les guides de maintien permettent alors de solidariser le câble à fibre optique avec l'élément tubulaire sans l'utilisation de mécanismes mobiles et/ou électriques.
• le câble de sécurité est un câble en acier (e.g. standard ou inoxydable), en matériaux composites ou en matériaux textiles. Ceci permet d'assurer la robustesse du dispositif de maintenance et d'assurer une protection à l'ensemble des composants. En effet, avantageusement, le câble de sécurité est configuré pour résister à au moins l'ensemble du poids du dispositif additionné d'un coefficient de sécurité pour prendre en compte les aléas de manœuvre (e.g. traction, choc...).
• il comprend en outre un ou plusieurs lests. Le lest permet d'assurer la descente du dispositif de maintenance dans le forage. Ceci permet d'assurer la descente totale dans le forage des deux câbles, de la pluralité des guides de maintien et de la pluralité de paires de butées ou de la pluralité de butées. En outre, le lest permet la mise en tension du ou des câbles de sécurité et à fibre optique.
• les guides de maintien présentent une forme longitudinale et sont traversés sur leur longueur par le câble de sécurité. Ceci permet d'assurer une parfaite sécurité du dispositif. En outre, cela permet un degré de liberté du câble de sécurité et d'éviter tout risque de rupture du dispositif.
• chaque guide de maintien comprend une conduite adaptée au câble à fibre optique, pour accueillir le câble à fibre optique. Cette caractéristique permet de sécuriser le câble à fibre optique et d'augmenter la qualité et la fiabilité de la fixation.
• les guides de maintien de la pluralité de guides de maintien peuvent être espacés les uns des autres d'une distance de l'ordre de la taille d'une section de l'élément tubulaire, par exemple, chaque guide de maintien est espacé d'au plus 20 mètres. Cela permet d'augmenter la précision de l'analyse.
• les guides de maintien présentent une forme longitudinale comportant deux extrémités et une portion centrale et les guides de maintien présentent à leurs extrémités un diamètre de section transversale inférieur au diamètre de section transversale de la portion centrale. Ceci permet de passer plus facilement d'éventuelles réductions de diamètre de l'élément tubulaire.
• il comprend en outre un équipement de mesures de pression et/ou de température et/ou acoustique. Ce ou ces équipements permettent de recueillir des données supplémentaires afin de parfaire la détermination de la position d'un point de blocage d'un élément tubulaire, mais également d'assurer une surveillance et un contrôle de l'élément tubulaire ou du point de blocage.

According to other optional characteristics of the maintenance device, the latter may optionally include one or more of the following characteristics, alone or in combination :

• it comprises a safety cable and each holding guide is arranged so as to allow a translational movement of the holding guides with respect to the safety cable. This characteristic makes it possible to increase the robustness of the maintenance device. In addition, this allows a degree of freedom between the safety cable and the holding guides, resulting in sliding of the safety cable inside each holding guide. This degree of freedom makes it possible to release the fiber optic cable during the measurement.
• it comprises a plurality of stops, each stop being coupled to the safety cable and to one of the holding guides so as to limit the movement of said holding guide relative to the safety cable. This increases and improves the security of the maintenance device, both during the descent into the tubular element of the maintenance device and during the ascent. The stops make it possible to improve the protection and the safety by constituting a protection of the fiber optic cable by avoiding that an excessive pulling force is imposed on it.

• it comprises a plurality of pairs of stops, each stop of a pair of stops being coupled to the safety cable and being positioned respectively on either side of one of the holding guides so as to limit the movement of said holding guide relative to the safety cable. The plurality of pairs of stops makes it possible to limit the movement of each holding guide relative to the safety cable. This also makes it possible to increase and improve the safety of the maintenance device, both during the descent into the tubular element of the maintenance device and during the ascent. The stops make it possible to improve the protection and the safety by constituting a protection of the fiber optic cable by avoiding that an excessive pulling force is imposed on it.
• the attachment means is selected from: a mechanical attachment means, a magnetic attachment means, an electromagnetic attachment means, a chemical attachment means, preferably an adhesive attachment means. The attachment means makes it possible to indirectly fix the optical fiber cable to the tubular element and more precisely to an internal wall of the tubular element.
• the attachment means of the holding guides allow fixed and removable attachment to the internal wall of the tubular element. A fixed attachment makes it possible, as long as it is active, to prevent any movement of a retaining guide relative to the tubular element. On the other hand, the fixing is removable so the holding guide can be detached.
• the holding guides include magnets and a clamping system. The magnets make it possible to ensure the fixing of the holding guides with the tubular element. The clamping system makes it possible to hold the fiber optic cable on the holding guides. The holding guides then make it possible to secure the fiber optic cable with the tubular element without the use of mobile and/or electric mechanisms.
• the safety cable is a steel cable (eg standard or stainless), composite materials or textile materials. This makes it possible to ensure the robustness of the maintenance device and to ensure protection for all the components. In effect, advantageously, the safety cable is configured to withstand at least the entire weight of the device plus a safety factor to take into account the hazards of maneuver (eg traction, shock, etc.).
• it further comprises one or more ballasts. The ballast ensures the descent of the maintenance device into the borehole. This makes it possible to ensure the total descent into the borehole of the two cables, of the plurality of holding guides and of the plurality of pairs of stops or of the plurality of stops. In addition, the ballast allows tensioning of the safety and fiber optic cable(s).
• the holding guides have a longitudinal shape and are crossed along their length by the safety cable. This makes it possible to ensure perfect safety of the device. In addition, this allows a degree of freedom of the safety cable and avoids any risk of breakage of the device.
• each holding guide includes a conduit suitable for the fiber optic cable, to accommodate the fiber optic cable. This feature secures the fiber optic cable and increases the quality and reliability of the fixing.
• the plurality of retaining guides may be spaced apart by a distance on the order of the size of a section of the tubular member, for example, each retaining guide is spaced at most 20 meters. This increases the precision of the analysis.
• the holding guides have a longitudinal shape comprising two ends and a central portion and the holding guides have at their ends a cross-sectional diameter smaller than the cross-sectional diameter of the central portion. This makes it easier to pass any reductions in diameter of the tubular element.
• it further comprises equipment for measuring pressure and/or temperature and/or acoustics. This or these pieces of equipment make it possible to collect additional data in order to perfect the determination of the position of a blocking point of a tubular element, but also to ensure monitoring and control of the tubular element or of the blocking point. .

According to another aspect, the invention relates to a system for determining the position of a blocking point of a tubular element comprising a measuring device distributed by reflectometry and a maintenance device according to the invention, said measuring device distributed by reflectometry being connected to the maintenance device and configured to carry out a measurement of deformation of the tubular element. The system makes it possible to determine the position of a blocking point in a simple and fast way. Indeed, such a system makes it possible to produce only a single measurement set. In addition, the measurements are precise, accurate and reliable. This also makes it possible to measure the deformations of the optical fiber over its entire length so as to determine where the tubular element is blocked.

• une étape de première mesure répartie par réflectométrie,
• une étape d'application d'une contrainte sur l'élément tubulaire ou de suppression d'une contrainte appliquée sur l'élément tubulaire antérieurement à l'étape de première mesure répartie par réflectométrie,
• une étape de seconde mesure répartie par réflectométrie, et
• une étape de détermination de la position du point de blocage de l'élément tubulaire par comparaison des première et seconde mesures par réflectométrie.

According to another aspect, the invention relates to a method for determining the position of a blocking point of a tubular element by means of a maintenance device comprising a fiber optic cable and a plurality of holding guides, each holding guide being fixed to the fiber optic cable and comprising a means of attachment to the tubular element, preferably to an internal wall of the tubular element, the maintenance device being inserted into the tubular element and the guides holding being fixed to the tubular element by means of the attachment means, said method comprising:

• a first measurement step distributed by reflectometry,
• a step of applying a stress on the tubular element or of removing a stress applied to the tubular element prior to the step of first measurement distributed by reflectometry,
• a step of second measurement distributed by reflectometry, and
• a step of determining the position of the blocking point of the tubular element by comparing the first and second measurements by reflectometry.

A method according to the invention makes it possible to check in a single measurement, typically a hundred meters of a tubular element. This saves considerable time. In addition, the measurements are reliable, accurate and precise. Moreover, the method according to the invention does not require successive anchoring steps at different heights of the walls of the tubular element to carry out the measurements. The maintenance device can therefore be lowered several meters or even hundreds of meters along the tubular element before carrying out the measurements necessary for determining the position of a blocking point. This again saves considerable time and reduces use of expensive and specific equipment. Furthermore, the method is secure because it does not require the use of an active sensor or an active anchor.

• les étapes de mesure de la déformation comportent le calcul de la rétrodiffusion de Brillouin dans la fibre optique au moyen d'un dispositif de mesure répartie de déformation. Ceci permet de réaliser les mesures en temps réel et de façon autonome. En outre, une telle étape est faiblement consommatrice d'énergie.
• il comprend en outre une étape de mesure de la longueur du câble à fibre optique déroulée. Ceci permet d'éviter toute sur-longueur d'un câble par rapport à l'autre. Cela minimise le risque de rupture.
• il comprend en outre une étape de mesure acoustique par un équipement de mesure de rétrodiffusion Rayleigh. Cette étape permet de recueillir des données afin de parfaire la détermination de la position d'un point de blocage d'un élément tubulaire, mais également d'assurer une surveillance et un contrôle de l'élément tubulaire ou du point de blocage.
• il comprend en outre une étape de mesure de pression par un équipement de mesure de rétrodiffusion Brillouin et/ou Rayleigh. Ceci permet de recueillir des données afin de parfaire la détermination de la position d'un point de blocage d'un élément tubulaire, mais également d'assurer une surveillance et un contrôle de l'élément tubulaire ou du point de blocage
• il comprend en outre une étape de mesure de température par un équipement de mesure de rétrodiffusion de Brillouin. Cette étape permet de recueillir des données afin de parfaire la détermination de la position d'un point de blocage d'un élément tubulaire, mais également d'assurer une surveillance et un contrôle de l'élément tubulaire ou du point de blocage.

According to other optional characteristics of the method, the latter may optionally include one or more of the following characteristics, alone or in combination :

• the deformation measurement steps comprise the calculation of the Brillouin backscattering in the optical fiber by means of a distributed deformation measurement device. This makes it possible to carry out measurements in real time and autonomously. In addition, such a step consumes little energy.
• it further comprises a step for measuring the length of the unwound optical fiber cable. This avoids any excess length of one cable compared to the other. This minimizes the risk of breakage.
• it further comprises an acoustic measurement step using Rayleigh backscatter measurement equipment. This step makes it possible to collect data in order to perfect the determination of the position of a blocking point of a tubular element, but also to ensure monitoring and control of the tubular element or of the blocking point.
• it further comprises a pressure measurement step using Brillouin and/or Rayleigh backscattering measurement equipment. This makes it possible to collect data in order to perfect the determination of the position of a blocking point of a tubular element, but also to ensure monitoring and control of the tubular element or of the blocking point.
• it further comprises a temperature measurement step using Brillouin backscattering measurement equipment. This step makes it possible to collect data in order to perfect the determination of the position of a blocking point of a tubular element, but also to ensure monitoring and control of the tubular element or of the blocking point.

According to another aspect, the invention relates to a tubular element comprising a maintenance device according to the invention for determining the position of a blocking point of said tubular element.

• [Fig 1] représente un schéma d'un mode de réalisation du dispositif de maintenance selon l'invention.
• [Fig 2] représente un schéma d'un mode de réalisation du dispositif de maintenance selon l'invention.
• [Fig 3] représente un schéma d'un mode de réalisation du dispositif de maintenance selon l'invention.
• [Fig 4] représente un schéma d'un mode de réalisation du dispositif de maintenance selon l'invention.
• [Fig 5] représente un schéma d'un guide de maintien selon l'invention.
• [Fig 6] représente un schéma d'un système pour déterminer la position d'un point de blocage d'un élément tubulaire selon l'invention.
• [Fig 7] représente un schéma d'un mode de réalisation du procédé de détermination de la position d'un point de blocage selon l'invention.
• [Fig 8A] représente un graphique d'une mesure absolue de déformation par fibre optique.
• [Fig 8B] représente un graphique d'une mesure relative de déformation par fibre optique.
• [Fig 9] représente un schéma d'un mode de réalisation du système d'assemblage selon l'invention.
• [Fig 10] représente un schéma d'un mode de réalisation du procédé de mise en place selon l'invention, les étapes en pointillées étant facultatives.

Other advantages and characteristics of the invention will appear on reading the following description given by way of illustrative and non-limiting example, with reference to the appended Figures:

• [ Fig 1 ] shows a diagram of an embodiment of the maintenance device according to the invention.
• [ Fig 2 ] shows a diagram of an embodiment of the maintenance device according to the invention.
• [ Fig.3 ] shows a diagram of an embodiment of the maintenance device according to the invention.
• [ Fig 4 ] shows a diagram of an embodiment of the maintenance device according to the invention.
• [ Fig.5 ] shows a diagram of a holding guide according to the invention.
• [ Fig 6 ] shows a diagram of a system for determining the position of a blocking point of a tubular element according to the invention.
• [ Fig 7 ] shows a diagram of an embodiment of the method for determining the position of a blocking point according to the invention.
• [ Fig 8A ] represents a graph of an absolute fiber optic strain measurement.
• [ Fig. 8B ] represents a plot of a relative fiber optic strain measurement.
• [ Fig.9 ] shows a diagram of an embodiment of the assembly system according to the invention.
• [ Fig. 10 ] represents a diagram of an embodiment of the installation method according to the invention, the dotted steps being optional.

[Description of the invention]

In the rest of the description, the expression “ blocking point ” corresponds to the jamming of a tubular element, for example in a borehole preventing the progression of this tubular element. A sticking point can be, for example, the consequence of a landslide, a restriction, or a deformation of the rock formation.

By “ drilling ” is meant in the sense of the invention the action of drilling and/or its result.

By “ position ” is meant within the meaning of the invention a precise location in the space occupied by the blocking point, for example over the entire height of the borehole, and therefore more particularly a depth or a distance relative to the surface.

The term “ tubular element” within the meaning of the invention preferably corresponds to a drill rod used for drilling a well, a casing, or casing. However, a tubular element can also correspond to a part, an object or a conduit, the length of which is greater than the width, for example of cylindrical or rectangular shape. Thus, this term can also correspond to any equipment forming part of the drill or completion string, such as a stabilizer, drill collar ("drill collar" in English terminology), seal ("packer" in Anglo-Saxon terminology), suspension olive (“hanger” in Anglo-Saxon terminology), or heavy rods (“heavy-weight” in Anglo-Saxon terminology).

The term “ constraint ” in the sense of the invention means a force applied to a material or a body. This force can be exerted by a torsion, a traction, a push or any other force resulting in a “ deformation ” or a displacement of the material or the body on which it is exerted.

By " deformation " is meant a change in shape or size of a material or body without exceeding the ultimate limit of the material or body in question. For example, a deformation within the meaning of the invention tends to stretch or compress a material or a body undergoing a force and in particular in the form of a constraint.

The terms " fixed ", " fixed ", or " fixed ", within the meaning of the invention correspond to the direct or indirect association of one element with respect to another without movement of these elements with respect to each other. other, irremovable or removable with one or more intermediate elements. Two elements can be fixed mechanically, electrically or linked by a communication channel.

The terms “ coupled ” or “ assemble ” and their derivatives within the meaning of the invention correspond to the attachment, to the direct or indirect, mobile or immobile, irremovable or removable connection with one or more intermediate elements. Two elements can be coupled mechanically, electrically or linked by a communication channel.

By “ connected ” within the meaning of the invention is meant a connection between at least two elements, the connection possibly being physical, electrical or digital.

The term " removable " within the meaning of the invention corresponds to the ability to be easily detached, removed or dismantled without having to destroy the fixing means either because there is no fixing means or because the means fasteners are easily and quickly removable (eg notch, screw, tab, lug, clips). For example, by removable, it should be understood that the object is not fixed by welding or by any other means not intended to allow the object to be detached.

By “ crossing ” is meant within the meaning of the invention, the penetration of a device from one end to the other, preferably in the longitudinal direction of the device and in its center. A degree of freedom, preferably a translational movement along the longitudinal axis of the device can be authorized.

The expression “ a single set of measurements ” is understood to mean, within the meaning of the invention, the absence of a succession of different types of measurements. This is a single type of measurement, carried out by reflectometry. Thus, within the meaning of the invention, a single measurement corresponds to carrying out measurements by reflectometry without moving the maintenance device, making it possible to identify the position of a blocking point.

By " process ", " calculate ", " display ", " extract ", " compare ", " measure " or more broadly " executable operation " within the meaning of the invention, an action performed by a device or a processor unless the context indicates otherwise. In this regard, operations refer to actions and/or processes of a data processing system, e.g. a computer system or an electronic computing device, which manipulates and transforms data represented as physical (electronic ) in the memories of the computer system or other devices of storage, transmission or display of information. These operations can be based on applications or software.

By " essentially " is meant in the sense of the invention at least 50% of the constitution, preferably at least 70% of the constitution, more preferably at least 90% of the constitution, even more preferably at least 95% of the constitution.

By “ accurate ”, “ reliable ”, “ precise ” is meant in the sense of the invention, preferably repeatable and exact measurements of the position of the blocking point, the precision of which is for example of the order of one meter.

In addition, the different characteristics presented and/or claimed can be advantageously combined. Their presence in the description or in different dependent claims does not exclude this possibility.

Current solutions for determining the position of a blocking point of a tubular element are generally long, laborious and expensive. In addition, they often require the insertion into the tubular element of expensive electronic equipment and a source of risk, particularly in the context of hydrocarbon drilling.

Thus, the inventors have developed a new maintenance device for determining the position of a blocking point of a tubular element in a borehole allowing speed and reliability, accuracy and precision of the measurements, and moreover increased safety (without no electrical system lowered into the borehole).

The invention will be described in the context of blocking a tubular element in a borehole. The invention is not limited, however, to this example, and can find applications in any configuration in which there is a blockage of equipment during drilling.

In the remainder of the description, the same references are used to designate the same elements.

According to a first aspect, the invention relates to a maintenance device 1 for determining the position of a blocking point 2 of a tubular element, preferably a drill pipe. A maintenance device 1 according to the invention makes it possible to overcome the difficulties encountered with the systems of the prior art. The implementation of a maintenance device 1 according to the invention is perfectly suited for use in the exploitation of the subsoil such as mining and oil exploitation, and more particularly drilling.

Indeed, a maintenance device 1 according to the invention is completely passive and therefore no electrical system is lowered into the borehole. This also makes it possible to secure the place of the drilling such as the drilling, the operators and the installations. In addition, the maintenance device 1 ensures high resistance.

A maintenance device 1 can be, according to a preferred embodiment of the invention, a cable, but the invention is not limited to a cable. Indeed, any type of device comprising a fiber optic cable 40 and a plurality of holding guides 20 can be implemented.

The Figure 1 schematizes an embodiment of a maintenance device 1 according to the invention. As illustrated, the maintenance device 1 comprises a fiber optic cable 40 and a plurality of holding guides 20 .

The maintenance device 1 comprises a plurality of holding guides 20 .

Each retaining guide 20 may comprise a means 21 for hooking the tubular element. Preferably the attachment means 21 makes it possible to fix the fiber optic cable 40 to the tubular element and more precisely to an internal wall of the tubular element. This attachment between the tubular element and the fiber optic cable 40 via the means 21 for attaching the holding guides 20 is preferably fixed and removable. The attachment means 21 is preferably arranged at the periphery of the central portion 20C of each holding guide 20 .

The attachment means 21 is selected from: a mechanical attachment means, a magnetic attachment means, an electromagnetic attachment means, a chemical attachment means, preferably an adhesive attachment means. A mechanical attachment means can for example be selected from: anchor, mobile arm, crampon or sealing gasket (“packer” in Anglo-Saxon terminology). A magnetic attachment means can for example be selected from: permanent magnet, electrostatic device. An electromagnetic attachment means can for example be selected from: an electromagnetic device, an electromagnet. A means of attachment chemical, preferably adhesive can for example be selected from: permanent adhesive, temporary adhesive, glue, tape, adhesive.

Thus, in particular, a hooking means 21 can correspond to a magnet, a plurality of magnets, permanent magnets, electromagnets, plastomagnets, moving parts or their combinations, configured to be fixed to the tubular element. Preferably, the attachment means 21 is a plurality of permanent annular magnets 22 . These magnets 22 can be coupled with a rod 24. The magnets 22 of the plurality of magnets on the rod 24 can be separated by a gap 23 in order to limit the direct interaction between two magnets 22. In addition, the number of magnet 22 of the plurality of magnets can be a function of the configuration of the tubular element. Indeed, depending on the friction force sought, the number of magnets 22 of the plurality of magnets will be high if the friction force must be high or reduced if the friction force sought must be low. Alternatively, the number of magnets 22 of the plurality of magnets can also depend on the characteristics of the tubular element.

In addition, the holding guides 20 can be attached to the fiber optic cable 40. The holding guides 20 of the plurality of holding guides can be spaced from each other by a distance on the order of the size of a section of the tubular element. For example, each holding guide 20 is spaced 20 meters, preferably 15 meters and more preferably 10 meters from the next holding guide 20. The distance separating two holding guides 20 is even more preferably greater than 2 meters. The distance between two holding guides 20 makes it possible to give the spatial resolution, when carrying out the measurements. For example, a distance of 2 meters between two holding guides gives a measurement spatial resolution of 2 meters equal to the spacing between two holding guides.

An optical fiber cable 40 generally consists of at least a core, an optical sheath and a coating. One or more fiber optic cable reinforcements 40 may be provided.

The core of the fiber optic cable 40 makes it possible to transport the optical signals between a light source and a receiver. The core can be of glass or polymer and is differentiated by its diameter. Thus, the fiber optic cable core 40 according to the invention may correspond to a multimode optical fiber or to a single-mode optical fiber or to multi-core fiber. The core can be for 62.5/125 µm (micrometer) multimode fiber, 50/125 µm or 9/125 µm for a single mode fiber. Preferably, the type of fiber optic cable is specific for strain measurement. For example, it can be a "tight-buffered" type fiber cable, for a tight fiber in the reinforcement, or a "loose-tube" type fiber cable. (or free fiber in French), that is to say that the fiber is free of any constraint inside the reinforcement, for a measurement of temperature and/or acoustic vibrations.

The optical cladding surrounds the core of the optical fiber. The sheath makes it possible to retain the light waves while allowing circulation over the entire length of the fiber. In addition, the sheath makes it possible to cause refraction.

The coating can be made of polymer. It surrounds the sheath and ensures the protection of the optical fiber, in particular by absorbing the shocks that the optical fiber cable 40 could undergo during its descent or ascent in a borehole. The thickness of the coating is for example between 250 μm and 900 μm.

Alternatively, fiber optic cable 40 has a fiber optic cable shield. Preferably, this fiber optic cable armor 40 is structured. This makes it possible to improve the fixing of the fiber optic cable to the retaining guides 20 . Indeed, this increases the coefficient of friction with the fixing means 27 by crushing the holding guide. This also makes it possible to improve the sensitivity of measurement of the deformation.

Preferably, the fiber optic cable is of the “tight-buffered” type. This isolates and protects the optical fiber. In addition, a “tight-buffered” type fiber optic cable allows improved measurement of the deformations of the fiber optic cable.

The length of the fiber optic cable 40 can be of the order of the depth of a borehole. For example a fiber optic cable length can be 5 Km (Kilometer).

A fiber optic cable 40 makes it possible to transport optical signals between a light source and a receiver.

Furthermore, the fiber is preferably attached to the outer frame of the fiber optic cable, which makes it possible to improve the sensitivity of the measurements. This allows precise measurements, to the meter or even to the centimeter, reliable and accurate.

The fiber optic cable 40 can be fixed to the tubular element by means of the holding guides.

In addition, one of the ends of the fiber optic cable 40 may include a sealing device 41 intended to seal the end of the fiber optic cable. This device 41 may have a diameter greater than that of the retaining guides 20 . This feature makes it possible to prevent the sealing device from passing through the retaining guides. The sealing device 41 also makes it possible to hold the fiber optic cable 40 in the holding guides. Preferably, the sealing device also makes it possible to limit the movement of the fiber optic cable. This is advantageous because the sealing device makes it possible to seal the end of the fiber optic cable while preventing the fiber optic cable from being released from the holding guides.

Advantageously, the fiber optic cable 40 withstands the temperature and pressure conditions present in a borehole. The fiber optic cable 40 can also be resistant to the various chemical compounds and elements present in a borehole.

Advantageously, the fiber optic cable 40 is able to be connected at the surface to a device 110 for distributed measurement by reflectometry which will be detailed below.

Furthermore, as illustrated in figure 2 , the maintenance device may include a security cable 10.

Advantageously, the security cable 10 has a tensile strength of more than 1 kN (kilonewton), preferably more than 2 kN and even more preferably greater than 20 kN. For example, the safety cable 10 can withstand at least a force which is equal to all the forces of the system by means of a predetermined safety coefficient. The safety cable 10 makes it possible to withstand the entire weight of the device while taking into account a safety factor to take into account the hazards of maneuver (traction if the device is blocked in the borehole, shock if the device is dropped suddenly ). This makes it possible to secure the maintenance device 1 both during its descent into the borehole and during its ascent. Thus, it is possible to exert a significant tensile force on the safety cable 10 if the maintenance device 1 becomes blocked during its use in the borehole, and this without causing the safety cable 10 to break.

The tensile strength defines the limit at break. Thus, the maintenance device 1 has a breakage limit greater than 1 kN, preferably 2 kN and even more preferably greater than 20 kN. Preferably, the breaking point is measured according to the ISO6892 standard.

For this, the security cable 10 can be made of stainless steel, carbon fiber or composite materials, textile materials or standard steel (not stainless).

Furthermore, the surface of the security cable 10 can be smooth or rough. Preferably the surface of the security cable 10 is rough. This makes it possible to improve the fixing of the stops 30, detailed below.

Preferably, the safety cable 10 is light; that is to say that its weight does not exceed more than 65 kg/km (kilogram per kilometer), preferably 30 kg/km. This facilitates its use and implementation.

The length of the safety cable 10 can be defined according to the drilling to be carried out. For example, the deeper the drilling, the longer the security cable 10 will be. For example, the security cable 10 may have a length greater than 2500 meters, preferably greater than 5000 meters. Preferably, the security cable 10 has a length between 10 meters and 2500 meters, and even more preferably between 10 meters and 5000 meters.

As illustrated in the figure 2 , the maintenance device may comprise a plurality of stops 30. Each stop 30 is advantageously coupled, preferably fixed, to the safety cable 10. In addition, they can be coupled to one of the holding guides 20 via a safety member 31 so as to limit the movement of said holding guide 20 relative to the safety cable 10.

Alternatively, as shown in picture 3 , the maintenance device 1 may comprise a plurality of pairs of stops 30. Each stop 30 of a plurality of pairs of stops is then coupled, preferably fixed, to the safety cable 10, respectively on either side of a holding guide 20 so as to limit the movement of said holding guide.

In addition, provision may be made for each stopper 30 to include a passage, such as a hole, for example in its center, allowing the safety cable to pass through each stopper.

The stops 30 are preferably of symmetrical double conical shape, the base of the cone of which faces each guide 20 for holding. In addition, the stops can be made of stainless steel, plastic, polymers, non-corrosive material, metal. Preferably, they are essentially made of aluminum to avoid corrosion. It also depends on the environment in which the device is introduced.

Each stop 30 may preferably have an outer diameter less than the outer diameter of the guides 20 for holding. Preferably, each stop 30 has an outer diameter greater than the outer diameter of the ends 20A, 20B of the guides 20 for holding. Alternatively, if each stop 30 has an outer diameter less than the outer diameter of the ends 20A, 20B of the holding guides 20, they have an outer diameter greater than the outer diameter of the projection 25, preferably of the pipe, of the holding guide 20 . This prevents the stops from passing through the holding guides 20 and vice versa.

Each stop 30 coupled to the safety cable 10 and to one of the holding guides 20, can be coupled to the holding guide via one of its ends, preferably at the downstream end of the holding guide 20, at namely end 20B.

Alternatively, each abutment 30 of the plurality of pairs of abutments can be arranged on either side of a holding guide 20 . One of the stops 30 of the pair of stops is arranged upstream of the holding guide 20 and the other stop 30 of the pair of stops is arranged downstream of said holding guide 20.

Each stop 30 can be a few centimeters (cm) upstream and/or downstream of each retaining guide 20, preferably 10 cm, more preferably 1 cm to 20 cm or 5 cm to 15 cm, from even more preferably at a distance favoring a maximum elongation of the order of 1% of the fiber optic cable. Thus, the number of pairs of stops 30, or the number of stops 30, is preferably between 10 and 500. Preferably the number of pairs of stops is equal to the number of guides.

In addition, each stopper 30 can be fixed to the safety cable 10. The fixing is preferably a fixing by crushing only on the safety cable 10 . the coupling of each abutment to the holding guide 20 is preferably direct, removable and extensible.

Each stop 30 makes it possible to control the maximum elongation of the fiber optic cable 40 which preferably does not exceed 1% to 1.5% in order to avoid a break in the fiber optic cable. Indeed, the fiber optic cable 40 is generally fixed in a removable manner to the holding guides 20, too great an elongation of the distance between two holding guides 20 could cause the fiber optic cable 40 to break. Each stop 30 makes it possible to limit the distance between two guides 20 for holding. Preferably, this spacing is calculated not to be greater than 1.5% of maximum elongation undergone by the cable 40 with optical fiber.

According to an optional embodiment and as illustrated in figure 4 , the maintenance device has two parts. A first part 1A does not include a holding guide while a second part 1B, also called a measurement section, includes the holding guides 20 . The first part 1A, for example several kilometers long (eg at least two km), preferably consists of one or two cables comprising the optical fiber and steel or composite materials. The first part 1A can therefore comprise the fiber optic cable 40 and the safety cable 10. Alternatively it can be formed from a single reinforced fiber optic cable. However, it does not include a holding guide. The second part comprises the holding guides 20. In addition, in this case, the maintenance device may comprise a joining system 60 of cables. Such a cable joint system 60 allows the fiber optic cable 40 to join the security cable to form a single reinforced fiber optic cable. Preferably, the fiber optic cable joins the safety cable after the measurement section via the specific junction system. In particular, the second part 1B may have an overlength compared to the safety cable, after the junction system 60.

As shown in figure 5 , the holding guides 20 advantageously have a longitudinal shape comprising two ends 20A, 20B and a central portion 20C. The holding guides 20 have at their ends 20A, 20B a diameter, preferably an outer diameter, of cross-section smaller than the diameter, preferably the outer diameter, of cross-section of the central portion 20C. This allows to facilitate the passage of the holding guides 20 in the tubular element and particularly of the different sections of the tubular element, when the internal diameter of the tubular element is reduced.

Alternatively, the holding guides 20 can be of cylindrical, oblong, elongated, tapered, tubular, spherical or spheroid shape. Preferably, the retaining guides 20 are cylindrical in shape.

Advantageously, the holding guides 20 can essentially consist of non-corrosive materials, stainless or of composites or of metal and preferably of aluminum. This prevents corrosion. It also depends on the environment in which the device is introduced.

In addition, each retaining guide 20 can be arranged to accommodate the safety cable 10. Thus, each holding guide can comprise a pipe, a cavity, a gap or a housing to accommodate the safety cable 10 . Preferably, each holding guide 20 comprises a conduit 25 formed in the holding guide 20 to accommodate the safety cable 10. This pipe 25 may protrude into the holding guide 20 over its entire length and preferably in its center. In other words, each holding guide 20 can be crossed by the safety cable 10, preferably in the longitudinal direction and in its center. In addition, each holding guide 20 can be arranged to allow a translational movement of the holding guides 20 relative to the safety cable 10. This allows a degree of freedom between the safety cable 10 and the holding guide 20, resulting in a sliding of the safety cable 10 inside the holding guide 20.

Each holding guide 20 can be arranged to accommodate the fiber optic cable 40. Thus, each retaining guide may comprise a pipe, a cavity, an orifice, a gap or a housing to accommodate the fiber optic cable 40. Preferably, each holding guide 20 may comprise a conduit 26. This conduit 26 may project into the holding guide 20 at the periphery of the central portion 20C of the holding guide 20. Preferably, this pipe 26 is diametrically opposed to the attachment means 21 . In addition, this pipe 26 is preferably of longitudinal shape in the direction of the length of the guide 20 for holding. The fiber optic cable 40 can penetrate the retaining guide 20 via this pipe 26. In addition, this pipe 26 has a fixing means 27.

The fixing means 27 of a holding guide 20 can correspond to a fixing by crushing, by gluing, rubbing or crimping. Preferably, the holding guides 20 comprise a fixing means 27 by crushing. This attachment means 27 can be arranged on the holding guide 20 and preferably on the surface opposite that of the attachment means 21. Preferably, the fixing means 27 can be close to the housing 26 which accommodates the fiber optic cable 40. Alternatively, this fixing means 27 can be arranged at each end of the housing 26 intended to accommodate the fiber optic cable 40. This makes it possible to increase the quality and reliability of the fixing. Each holding guide 20 can be attached to a fiber optic cable 40. The fixing means 27 makes it possible to fix the fiber optic cable 40 to the guide 20 for holding. This attachment does not allow any degree of freedom between the holding guide 20 and the fiber optic cable.

Thus, the number of holding guide 20 fixed to the fiber optic cable 40 can be between 2 and 500. The number of holding guide 20 crossed by the security cable 10 can be between 2 and 500. For example, to a 5 km long fiber optic cable, the number of holding guides is at least two, one at the bottom of the borehole and a second at the head of the borehole.

In addition, a maintenance device 1 according to the invention may comprise one or more ballast(s) 50. A ballast 50 within the meaning of the invention may correspond to a weight, a pig, a load bar. Preferably, it is a pig comprising arcuate springs (bow-springs in Anglo-Saxon terminology). This allows the centering of the ballast 50 in the tubular element. Indeed, the ballast 50 is fixed to one of the ends of the safety cable 10 and/or of the fiber optic cable 40. This ballast 50 can also be likened to a rod, preferably made of metal, several meters long and centered inside the tubular element by the bow-springs.

The weight of the ballast 50 must be sufficient to cause the total descent of the maintenance device 1 into the tubular element. Typically, the sum of the ballast, the guides and the stops must be greater than the frictional force created by the attachment means, for example the magnets.

The maintenance device 1 may further comprise equipment for measuring pressure, and/or temperature and/or acoustics. The coupling of the fiber optic cable 40 to the internal walls of the tubular element thanks to the holding guides 20 makes it possible to carry out seismic measurements VSP ("Vertical Seismic Profile" in English terminology) thanks to the use of optical fiber . Specific measuring equipment called DAS (“Distributed Acoustic Sensing” in English terminology) can also be added to the maintenance device 1 . Pressure and also temperature measurements can be made using the optical fiber installed in the borehole. However, for these latter measurements, there is no advantage in the fiber being coupled to the tubular element by the holding guides 20 . The maintenance device 1 can comprise Rayleigh backscatter measurement equipment for acoustic measurements. The maintenance device 1 can comprise Brillouin backscattering measuring equipment for temperature and/or deformation measurements. The maintenance device 1 can comprise Brillouin and/or Rayleigh backscattering measuring equipment for pressure measurements.

Thus, such a maintenance device 1 in addition to allowing the position of a blocking point 2 of a tubular element to be determined can also, thanks to pressure, and/or temperature and/or acoustic measurement equipment, allow to complete the analysis of a blocking point 2, its nature, its composition. This can also make it possible to confirm the blocking point 2 of the tubular element. In addition, this feature also allows measurements to be made independently of a blockage.

According to another aspect, the invention relates to a system 100 for determining the position of a locking point 2 of a tubular element.

The occurrence of a blocking point 2 preventing the progress of a borehole is unpredictable and often the consequence of external conditions, for example a landslide or landslide. However, it is also possible that the equipment gets stuck, deteriorates or separates causing the stoppage of the progress of the drilling. In addition, the position of the blocking point 2 can be random over the entire height of the borehole but can also be random depending on the length of the equipment (eg tubular element) inserted into the borehole. Such a system 100 according to the invention makes it possible to determine the position of a blocking point 2 simply and quickly. Indeed, this system 100 makes it possible to carry out only one set of reflectometry type measurements. In addition, the measurements are precise, accurate and reliable.

The figure 6 represents one embodiment of such a system 100 according to the invention. This system comprises in particular a maintenance device 1 according to the invention and a device 110 for distributed measurement by reflectometry. The device 110 for distributed measurement by reflectometry is preferably connected to the maintenance device 1 and is configured to measure the deformation of the tubular element 3 . Advantageously, the device 110 for distributed measurement by reflectometry is on the surface. This allows the measurement results to be retrieved directly from the surface.

The device 110 for distributed measurement by reflectometry makes it possible to measure the deformations of the fiber optic cable 40 over its entire length so as to determine the place where the tubular element 3 is stuck. The measurement carried out is preferably a B-OTDR type measurement (Brillouin Optical Time Domain Reflectometry in English terminology or optical time domain reflectometry). Thus, the device 110 for distributed measurement by reflectometry is preferably of the B-OTDR type. This type of device 110 is also referred to as a fiber optic sensor distributed by Brillouin backscatter.

Alternatively, other measurement devices can be envisaged such as Bragg grating sensor, Rayleigh scattering sensor (phase-OTDR), OFDR (for Optical Frequency Domain Reflectometry in English terminology or Optical Frequency Domain Reflectometry in French).

Such measuring devices are used for the permanent control of the integrity and safety of systems and structures in the petroleum industry. Briefly, a light signal is injected into an optical fiber and the light signal backscattered by the optical fiber then makes it possible to deduce the structural state of the tubular element. Advantageously, these optoelectronic devices for measurement distributed by Brillouin backscattering measure in real time at any point of the optical fiber of the optical fiber cable 40.

The device 110 for distributed measurement by reflectometry can in particular comprise a light source emitting a continuous light signal. This light source is advantageously embodied by a laser, preferably a DFB (from the acronym “Distributed Feedback”) laser, using a Bragg grating. The wavelength emission λ0 is preferably equal to 1550 nm, at the corresponding frequency v0. The line of the emitted light wave is centered on the emission wavelength λ0 and its width is at most 1 MHz (MegaHertz).

This device 110 for distributed measurement by reflectometry comprises at least one acousto-optic modulator. It can also include one or more amplifiers if necessary to provide gain. The acousto-optic modulator transforms the continuous signal of frequency v0 into a pulsed signal of frequency vp = v0 + vA , where vA is the frequency specific to the modulator, and is generally greater than or equal to 100 and less than or equal to 500 MHz, from preferably of the order of 200 MHz.

The local oscillator advantageously comprises a circulator which directs the incident continuous light signal, at the frequency v0, coming from the laser, into a reference optical fiber. This reference optical fiber is advantageously identical to the optical fiber under test. The reference fiber is not subject to any deformation. It is placed at a reference temperature, generally between 18 and 25°C (Celsius), preferably at a temperature of the order of 20°C. This reference fiber also makes it possible to emit a signal by Brillouin backscatter in response to the continuous signal emanating from the light source, so that the local oscillator makes it possible to transform the incident frequency v0 into a frequency vOL = v0 + vBref, where vBref represents the Brillouin frequency of the reference optical fiber, which is in the same frequency range as the vBz frequency from the signal backscattered by the optical fiber under test. The Brillouin frequency of the reference optical fiber is therefore located in a frequency range around 11 GHz, generally between 10.5 GHz and 11.5 GHz. The circulator of the local oscillator then sends the backscattered signal to the coupler to mix it with the backscattered signal coming from the optical fiber under test.

Alternatively, Brillouin and/or Rayleigh backscatter measuring equipment comprises a light source emitting a continuous light signal. This light source is advantageously embodied by a laser, preferably a DFB (from the acronym “Distributed Feedback”) laser, using a Bragg grating. The emission wavelength λ ₀ is preferably equal or substantially equal to 1550 nm, at the corresponding frequency v ₀ . The line of the emitted light wave is centered on the emission wavelength λ ₀ and its width is at most 1 MHz.

Advantageously, the light source is frequency tunable and it is possible to vary its frequency continuously at a speed of at least 1 GHz/s (Gigahertz per second) over an interval of at least 125 GHz. More preferably, the light source is capable of emitting continuous laser radiation at an optical frequency v ₀ which can be varied, over the duration of all the acquisitions, according to a continuous ramp of at least 250 GHz. This frequency modulation must be continuous and not in frequency steps and thus makes it possible to reduce the effects of intrapulse interference and therefore the noise. This feature is particularly important when Rayleigh backscatter tracking is desired.

The light source, for example a laser, emits a moderately powerful continuous light signal, typically of the order of 20 mW, in an optical fiber connecting it to a first coupler or to a third coupler.

The first coupler, receiving the light signal via light source or via the first arm of the third coupler, is capable of dividing said continuous light signal into two signals of identical frequency distributed in two arms.

The first arm connects the first coupler to a reference fiber unit comprising a reference fiber, said reference fiber unit being capable of emitting another light signal of frequency v ₀ -v _brief , where v _brief is the Brillouin frequency of the fiber reference, intended to be transmitted to the modulator or to be mixed with said initial signal by a fourth coupler. Thus, the reference block makes it possible to send the information back in a lower frequency band, thus improving the performance of the device. The reference optical fiber is kept without deformation and at a reference temperature. The second arm connects the first coupler to a second coupler located downstream of the modulator and is capable of transmitting to the second coupler a continuous light signal at a frequency v ₀ , thus constituting a local oscillator. More particularly, the second arm connects the first coupler to a second coupler located upstream of the photo-detection module and preferably it is positioned just before said photo-detection module.

The first coupler is able to direct enough energy from the light signal to the first arm so as to exceed the Stimulated Brillouin Scattering threshold and so that, in the reference fiber, the backscattered wave is shifted in frequency of -v _short compared to the optical wave. Advantageously, the first coupler is capable of directing the majority of the energy of the light signal towards the first arm. Preferably, the first coupler is capable of directing more than 70%, so more preferably more than 80%, even more preferably substantially 90% of the signal light energy to the first arm.

The reference block advantageously comprises a circulator which directs the incident continuous light signal, at the frequency v ₀ , coming from the first coupler, into a reference optical fiber. This reference optical fiber may be identical to the optical fiber to be tested. Advantageously, the reference fiber is not subjected to any deformation. It is placed at a reference temperature, generally between 18 and 25°C, preferably at a temperature of the order of 20°C. This reference fiber also makes it possible to emit a signal by Brillouin backscatter in response to the continuous signal emanating from the light source, so that the reference block makes it possible to transform the incident frequency v ₀ into a frequency v _br = v ₀ - v _Short , where v _Short represents the Brillouin frequency of the reference optical fiber, and which is for example in the same frequency range as the frequency v _bAS from the signal backscattered by the optical fiber to be tested. Furthermore, advantageously, the reference optical fiber of the reference fiber block has a Brillouin frequency different from that of the optical fiber to be tested. For example, the reference optical fiber has a Brillouin frequency shifted by at least 200 MHz, preferably by at least 300 MHz with respect to the Brillouin response of the fiber to be measured. Preferably, the Brillouin frequency of the reference optical fiber has a frequency difference with the Brillouin frequency of the optical fiber to be tested, comprised between 300 MHz and 1 GHz. Thus, this avoids any spectral overlap of the Rayleigh and Brillouin spectra while limiting the requirements for subsequent signal processing. Indeed, the photo-detection module located at the end of the optoelectronic assembly receives a signal from the Rayleigh backscatter which is modulated at the frequency of the acousto-optic modulator v _A (for example 200 MHz) and from the Brillouin backscatter modulated at the frequency (v _bAS - v _short + v _A ) without there being any overlap between the two spectra.

Such an architecture makes it possible to position the reference fiber on the same optical arm as the optical fiber to be tested. This has the advantage of improving the quality of measurement by having a signal in the local oscillator coming directly from the source and therefore without interference at low frequencies. It is therefore then not necessary to use a low-frequency electric filter at the output of the photo-detection module. This configuration also makes it possible to measure the anti-Stokes line of the Brillouin backscatter and, unlike the devices of the prior art, to access measurements close to the DC (for example around 100 MHz) in the electrical domain where it was hitherto not possible to make reliable measurements.

The third coupler makes it possible to divide the incident light signal emitted by the light source, into two signals of identical frequency distributed in two arms of the device.

The first arm connects the third coupler to the first coupler and the first arm is capable of transmitting to the first coupler a continuous light signal at a frequency v ₀ . The second arm connects the third coupler to a fourth coupler located upstream of the modulator and this second arm is capable of transmitting to the fourth coupler an initial signal at a frequency v ₀ .

Advantageously, the third coupler is capable of directing the majority of the energy of the light signal towards the first arm. Preferably, the third coupler is able to direct more than 70%, more preferably more than 80%, even more preferably substantially 90% of the energy of the light signal towards the first arm.

As specified, the fourth coupler is able to mix the initial signal v ₀ coming from the second arm of the third coupler with the light signal of frequency v ₀ - v _brief coming from the reference fiber and to inject them into the modulator. The signals coming from the reference optical fiber are therefore recombined with the initial signal v ₀ in the fourth coupler. At the output of the fourth coupler, a signal is obtained which contains a signal at the frequency v ₀ −v _briefly coming from the reference optical fiber and a signal at the same frequency as the initial signal v ₀ .

• une composante continue de fréquence v₀ - v_bref, transformée en une composante impulsionnelle de fréquence v_p1 = v₀ - v_bref + v_A, et
• une composante continue de fréquence v₀, transformée en une composante impulsionnelle de fréquence v_p2 = v₀ + v_A.

The modulator is able to impose a frequency shift of at least 100 Mhz on the continuous signal and to transform it into a pulsed signal intended to be injected into an optical fiber to be tested. Preferably, the modulator is an acousto-optic modulator. The modulator can be associated with one or more amplifiers if necessary to provide gain. The signal from the modulator has at least two components,

• a continuous component of frequency v ₀ - v _brief , transformed into an impulsive component of frequency v _p1 = v ₀ - v _brief + v _A , and
• a continuous component of frequency v ₀ , transformed into an impulsive component of frequency v _p2 =v ₀ +v _A .

The modulator is capable of generating a pulse signal having a frequency shifted with respect to the frequency of the continuous light signal. The frequency shift v _A applied to said shifted frequency may be greater than or equal to 100 MHz. The frequency v _A is the frequency specific to the modulator and is generally greater than or equal to 100 MHz and less than or equal to 1 GHz, preferably substantially equal to 200 MHz. The temporal width of the pulse thus generated can for example be between 10 ns and 500 ns, preferably it is substantially equal to 20 ns. The pulsed signal is then directed to a circulator which then injects it into the optical fiber to be tested, on which the distributed measurement must be performed. When the pulsed signal passes, the optical fiber emits a signal in the opposite direction by spontaneous Brillouin backscattering at the frequency v _F1 = v ₀ - v _{short +} v _A + v _bAS(z); and v ₀ - v _{brief +} v _A - v _bS(z) in which v _bAs is the Brillouin anti-Stokes frequency to be measured at any point of coordinate z along the optical fiber. v _bS(z) is the Brillouin Stokes frequency. The optical fiber also emits a signal in the opposite direction by Rayleigh backscattering at the frequency v _F2 =v ₀ +v _A .

These backscattered signals are directed, by the circulator, to the second coupler where they are recombined with a signal v ₀ originating from the local oscillator. Furthermore, advantageously, the second arm can comprise a polarization scrambler then arranged upstream of the inputs of a second coupler. This makes it possible to reduce the effects of interference due to the polarization between the arm of the local oscillator and the measurement arm, also called the “pump” arm, and located between the circulator and a second coupler.

The second coupler is able to couple the signal from the local oscillator to the backscatter signal coming from the optical fiber to be tested before transmitting it to the photo-detection module. The second coupler can be associated with optional modules such as a separation module (polarization beam splitter) or polarization hybridization. The backscatter signal can be modulated at least to a Brillouin frequency v _rB equal to v ₀ - v _short + v _A + v _bAS , where v _bAs is the anti-Stokes Brillouin backscatter frequency that can be measured at any point z of the optical fiber to be tested. This gives the possibility to the user to measure the anti-Stokes line of Brillouin backscattering while benefiting from a local oscillator without interference at low frequencies and thus improves the quality of the measurement.

The backscatter signal coming from the optical fiber to be tested can also be modulated at a Rayleigh frequency v _rR equal to v ₀ +v _A . This is possible when the device according to the invention comprises the third coupler and fourth coupler. This second coupler then allows the Rayleigh backscatter created in the optical fiber under test to couple with the frequency of the local oscillator. Thus, the device according to the invention also makes it possible to measure the Rayleigh backscatter spectrum. Preferably, the backscatter signal is modulated at a frequency v _rR equal to v ₀ +v _A and at a frequency v _rB equal to v ₀ -Vbrief +v _A +v _bAS .

This or these beats are electronically detectable through the use of a photo-detection module positioned downstream of the second coupler and it is capable of transmitting the backscatter signal received to a processing module. The photo-detection module comprises at least one photo-detector. Advantageously, the photo-detection module has a bandwidth of at least 800 MHz, preferably of at least 1 GHz. The photo-detection module located at the end of the optoelectronic assembly is capable of receiving a signal from Rayleigh backscattering modulated at the frequency of the acousto-optic modulator v _A and Brillouin backscattering modulated at the frequency (v _BAS - v _brief + v _A ). Under these conditions, at the output of the photo-detection module, the electrical signal obtained corresponding to the beats detected at the frequency of v _Batt1 = v _A +(v _bAs - v _Short ) corresponding to the Brillouin backscattering and at the frequency of v _Batt2 = v _A corresponding to Rayleigh backscatter. Thanks to the architecture of the device according to the invention, these beats were obtained from a single measurement and a single optical fiber to be tested. In addition, these beats have a lower frequency than the incident signals because the frequency v ₀ from the light source is eliminated. Typically, a first beat corresponding to _Batt1 = v _A +(v _bAs - v _Short ) has a frequency greater than 200 MHz, and preferably around 500 MHz, and a second beat corresponding to v _Batt2 = v _A has a frequency par example substantially equal to 200 MHz, corresponding to the order of magnitude of the frequency specific to the modulator. Indeed, v _A - (v _bS + v _Short ) is at around 20 GHZ and therefore out of band. The optical configuration therefore makes it possible to increase the efficiency of the photo-detection module by limiting the bandwidth to less than 2 GHz instead of 11 GHz, preferably to less than 1 GHz, for example between 400 MHz and 1 GHz.

Advantageously, the device according to the invention may not include a low-frequency electric filter at the output of the photo-detection module. Indeed, as specified previously, the positioning of the reference fiber on the same optical arm as the optical fiber to be tested makes it possible to improve the quality of measurement by having a signal in the local oscillator without interference at low frequencies. By removing these interference at low frequencies, this configuration also gives access to information that cannot be used with the configurations of the prior art (eg <100 MHz).

The beat signal(s) obtained can then be digitized, by means of an analog - digital converter module. Then they are processed by a digital processing module. Advantageously, the analog-to-digital converter module has a bandwidth of at least 800 MHz, preferably of at least 1 GHz and a sampling rate of at least 1.6 Gech/s, preferably of at least 2 Gech/s.

The processing module is advantageously configured to link said Brillouin anti-Stokes frequency v _bAs to a temperature value and/or to a strain value at any point “z” of said optical fiber to be tested. Thus, it is capable of separating the temperature measurement and the deformation measurement in order to obtain, from a single measurement, distinct temperature and deformation values. The latter may include an acquisition card which makes it possible to acquire the signal generated by the photo-detection module and therefore have a bandwidth and a sampling frequency capable of analyzing a signal corresponding to: v _A + v _bAs - v _brief . Thus, advantageously, the processing module is capable of measuring a signal having a bandwidth of at least 800 MHz, preferably of at least 1 GHz and a sampling rate of at least 1.6 Gech/s, preferably at least 2 Gech/s with the aim of detecting the two spectra simultaneously (Brillouin spectrum and Rayleigh spectrum). In addition, advantageously, it is appropriate to use an acquisition card with a high resolution such as for example a resolution greater than or equal to 10 bits. This makes it possible, considering the low intensity variations of the Brillouin backscattered spectrum as a function of temperature, to achieve an accuracy of the order of 1°C. The analog-to-digital converter and processing modules can be separate but can be integrated into a single and same assembly positioned directly after the photo-detection module.

The processing module is capable of dividing the digitized signal into a plurality of sections (T1...Ti...TN) by applying a sliding time window of the rectangular or Hamming, or Hann or Blackman type window. Harris, each section having a width equal to the temporal width of a pulse of the pulsed signal injected into the optical fiber to be tested, the width of each section also being centered around a date t corresponding to a coordinate point z of said optical fiber to be tested.

In addition, the digital processing module advantageously uses a discrete fourier transform algorithm (preferably fast), by means for example of a logic integrated circuit known by the English acronym FPGA (for “Field Programmable Gate Array”). It thus makes it possible to directly calculate the Brillouin frequency, the total intensity of the Brillouin backscattering and/or the total intensity of the Rayleigh backscattering at any point of coordinate “z” of the optical fiber under test. The digital processing module also makes it possible to average the spectra obtained in the frequency domain, for each point z of said fiber, at the end of the application of the discrete Fourier transform algorithm (preferably fast), in order to determine the distributed measurement of the frequency variation all along said optical fiber under test.

According to another aspect, the invention relates to a method 200 for determining the position of a blocking point 2 of a tubular element 3 by means of a maintenance device 1 comprising a fiber optic cable 40 and a plurality of holding guides 20 . Each retaining guide 20 can be fixed to the fiber optic cable 40 and comprise means 21 for attaching to the tubular element 3 . In addition, the maintenance device 1 is preferably inserted into the tubular element 3 and the holding guides 20 are fixed to the tubular element 3 via the attachment means 21 .

Preferably, the method 200 for determining the position of a blocking point 2 of a tubular element 3 by means of a maintenance device 1 comprises the use of a safety cable 10, a plurality of guides 20 for holding, a plurality of pairs of abutments 30 or a plurality of abutments 30 and a fiber optic cable 40.

Such a process, illustrated in figure 7 , according to the invention makes it possible to control in a single set of measurements a hundred meters of the tubular element 3 . This saves considerable time. In addition, the measurements are accurate, reliable and precise. The method 200 according to the invention also allows a considerable time saving and a reduction in the use of expensive and specific equipment. Furthermore, the method is secure because it does not require the use of an active sensor.

• une étape 240 de première mesure répartie par réflectométrie,
• une étape 250 d'application d'une contrainte sur l'élément 3 tubulaire ou de suppression d'une contrainte appliquée sur l'élément 3 tubulaire antérieurement à l'étape 240 de mesure répartie par réflectométrie,
• une étape 260 de seconde mesure répartie par réflectométrie, et
• une étape 290 de détermination de la position du point 2 de blocage de l'élément 3 tubulaire par comparaison des première et seconde mesures réparties par réflectométrie.

A method 200 for determining the position of a blocking point 2 comprises

• a step 240 of first measurement distributed by reflectometry,
• a step 250 of applying a stress to the tubular element 3 or of removing a stress applied to the tubular element 3 prior to the step 240 of distributed measurement by reflectometry,
• a step 260 of second measurement distributed by reflectometry, and
• a step 290 of determining the position of the blocking point 2 of the tubular element 3 by comparing the first and second measurements distributed by reflectometry.

In addition, a method 200 according to the invention may comprise a step 210 of producing a constraint, a step 220 of inserting the maintenance device into the tubular element and/or a step 230 of fixing the holding guides to the tubular element 3. Furthermore, a method 200 according to the invention does not require the repetition of a plurality of measurements but makes it possible, in a single measurement, to identify the position of a blocking point over several tens of meters.

The step 210 of producing a constraint on the tubular element can be carried out up to the depth where the tubular element 3 is wedged. The constraint can be carried out by traction or by any means making it possible to produce a uniform deformation over the entire length of the tubular element 3 . This constraint on the tubular element is for example maintained throughout the step 220 of inserting the maintenance device into the tubular element. Thus, the creation of a constraint can be implemented before the step 220 of inserting the maintenance device 1 into the tubular element as illustrated on the figure 7 or after inserting the fiber optic cable and before attaching the retaining guides (not shown).

The step 220 of inserting the maintenance device 1 into the tubular element 3 may comprise the insertion of the safety cable 10 and the fiber optic cable 40 into the tubular element 3 in parallel. In addition, this makes it possible to cover several hundred meters during a single insertion step 220 .

As part of a maintenance device 1 comprising two parts 1A and 1B, as illustrated in figure 4 , only one cable can be unrolled on the surface.

Such a method may further comprise a step 225 of measuring the length of the unwound optical fiber cable 40 . Preferably, this step is carried out in parallel with the step 220 of inserting the maintenance device 1 into the tubular element 3 . In addition, the length of unwound optical fiber cable 40 can be measured continuously and permanently. Alternatively, the length of the unwound security cable 10 can also be measured in parallel with the length of the unwound fiber optic cable 40. This avoids any overlength of one cable compared to the other. This therefore makes it possible to eliminate the risk of one of the cables breaking.

In the case where a single cable is unwound on the surface, preferably in the case of a cable illustrated in figure 4 , there is only one measurement of the length of the unwound cable. In fact, the fiber optic and safety cables come together, so only one cable is present on the surface.

The step 230 of fixing the holding guides 20 to the tubular element 3 makes it possible to fix the fiber optic cable 40 to the internal wall of the tubular element 3. This improves the precision, reliability and accuracy of the measurements. In addition, during this step, the weight, in particular of the ballast(s) 50, can be neutralized. For this, a tensile force can be exerted on the safety cable 10 so as to raise the weight(s) 50 when all the holding guides 20 are fixed. This prevents one of the stops 30 from being in contact with the corresponding holding guide 20 . In addition, this allows the tension forces of the fiber optic cable 40 and the friction forces created by the holding guides 20 to cancel each other out.

The step 240 of first distributed measurement by reflectometry of the optical fiber is preferably a B-OTDR type measurement. Alternatively, the measurement can be of the FDR (Frequency Reflectometry) type. More particularly, the measurement carried out can be of the calibration type which is carried out once the maintenance device 1 has been lowered and before the relaxation or the creation of the stress on the tubular element 3 . The measurement step may comprise the calculation of the Brillouin backscattering in the optical fiber by means of a device 110 for distributed measurement by reflectometry. The step 240 of first distributed measurement of the deformation of the optical fiber is preferably carried out during the constraint.

During distributed reflectometry measurements, laser 1 of distributed reflectometry measurement device 110 emits a pulsed signal of frequency vp=v0+vA. The temporal width of the pulse thus generated is for example between 10 ns and 200 ns, preferably it is 20 ns. The pulsed signal is then directed to a circulator which then injects it into the optical fiber, on which the distributed measurement must be performed.

When the pulsed signal passes, the optical fiber emits a signal in the opposite direction by spontaneous Brillouin backscattering at the frequency vF=v0+vA+vBz; vBz being the Brillouin frequency to be measured at any z-coordinate point along the optical fiber. This backscattered signal is directed by the circulator to the coupler where it is recombined with a signal coming from the local oscillator forming the second arm of the device.

The signals coming from the optical fiber under test and from the reference optical fiber are therefore recombined in the coupler. At the output of the coupler, a signal is obtained which contains a beat between the signal originating from the optical fiber under test and from the reference optical fiber of the local oscillator. This beat, of lower frequency, is electronically detectable thanks to the use of a photo-detector, with a bandwidth of less than 1 GHz, preferably 500 MHz. At the output of the photo-detector, an electrical signal corresponding to the beat detected at the frequency of vBatt=vA+(vBz-vBref) is therefore obtained. The beat has a lower frequency than the incident signals because the frequency v0 from the light source is eliminated. Typically, the beat has a frequency below 500 MHz, and preferably around 200 MHz, corresponding to the order of magnitude of the frequency specific to the acousto-optic modulator.

The beat signal obtained is then digitized, by means of an analog-to-digital converter module. Then it is processed by a digital processing module.

The advantageous configuration of the device 110 according to the invention makes it possible to dispense with all the prior checks necessary when using a Brillouin ring laser in order to avoid disturbances on the signal (by laser cavity instability). It also makes it possible to reduce the frequency to be detected by the photo-detector to less than 500 MHz, and more particularly in a frequency band centered around 200 MHz. The optical configuration therefore makes it possible to increase the efficiency of the photo-detector by limiting the bandwidth to less than 1 GHz instead of 11 GHz, preferably to 500 MHz.

The digital processing module, for its part, advantageously uses a fast fourier transform algorithm FFT, by means for example of a logic integrated circuit known by the English acronym FPGA (for “Field Programmable Gate Array”). It thus makes it possible to directly calculate the Brillouin frequency at any point of coordinate z of the optical fiber. The digital processing module also makes it possible to average the spectra obtained in the frequency domain, for each point z of said fiber, at the end of the application of the FFT fast fourier transform algorithm, in order to determine the measurement distribution of the frequency variation all along said optical fiber under test.

When the measurement of the deformation of the optical fiber during the constraint is finished, the method can comprise a step 250 of applying a constraint or of removing the constraint applied to the tubular element 3 . For example, the deformation which was applied is lifted, the tubular element 3 is then in a relaxed state.

The method can include a step 260 of second measurement distributed by reflectometry. Preferably, this second measurement is carried out after removal of the constraint. The step 260 of measuring the deformation can comprise the calculation of the Brillouin backscattering in the optical fiber by means of a device 110 for distributed deformation measurement. Preferably, it is a B-OTDR type measurement. This makes it possible to measure compression or deformation of the fiber optic cable 40.

The method may comprise a step 290 of determining the position of the blocking point 2 of the tubular element 3 by comparing the first and second measurements distributed by reflectometry. This allows the deformation of the optical fiber to be determined during stress and after stress removal. The comparison of these two measurements gives the position of the change of state of the tubular element. Typically on a relative Brillouin measurement of deformation, when the difference between the measurement before relaxation of the tubular element and after relaxation is zero then the tubular element is jammed. When the relative measurement of deformations measured is proportional to the force exerted on the surface on the tubular element 3, then the latter is not jammed. Thus the method comprises only one set of measurements. In addition, the method saves time while being passive and more secure.

Two examples of results for determining the position of blocking point 2 are presented to the figure 8A and 8B .

The figure 8A represents the measurements distributed by strain optic fiber. A typical measurement of absolute strain is made by a fiber optic measurement device 110 on the fiber optic cable 40 present in the invention. The fiber optic cable is placed at a depth of about 400 meters in the tubular element 3. Only one set of measurements is made, one measurement when the stress on the tubular element is present and one measurement when the stress on the tubular element is removed. On the figure 8A the results have different values up to a distance of 450 meters. After this distance, the two measurements are identical. The measurement carried out makes it possible to conclude that the tubular element is stuck in the borehole from a depth of 450 meters. The measurement is precise to the nearest meter, reliable and accurate. Plus, it's quick and easy.

The figure 8B represents distributed optical fiber strain measurements. A relative deformation measurement is carried out by an optical fiber measurement device 110 on the optical fiber cable 40 according to the invention. The fiber optic cable is placed at a depth of about 400 meters in the tubular element 3. A measurement is made when the stress on the tubular member is present and a measurement is made when the stress on the tubular member is removed. On the figure 8B , the gross step variation indicates the depth from which the tubular element is wedged. The measurement is also precise, fair and reliable. It is also simple and quick.

The method may further comprise a step 270a of acoustic measurement. This makes it possible to complete the method for determining the blocking point 2 of a tubular element 3 . Indeed, this can allow the supply of additional information, such as for example the nature of the blocking, for example a blocking in torsion or a blocking in traction. For this, the method can comprise Rayleigh backscattering equipment for acoustic measurements, VSP equipment (Vertical Seismic Profiling in English terminology or vertical seismic profile in French), a device for generating acoustic vibration at the desired depth.

The method may further comprise a step 270b of pressure measurement. The method may further comprise a step 270c of temperature measurement. That can allow the provision of additional information, but also monitoring of the blocking point 2 or of the tubular element 3. For this, the method can comprise Brillouin backscattering measuring equipment for temperature and/or deformation measurements. The method may also include Brillouin and/or Rayleigh backscatter measurement equipment for pressure measurements.

According to another aspect, the invention relates to a system 300 for assembling a maintenance device 1 for determining the position of a blocking point 2 of a tubular element 3.

The system, shown in figure 9 may include a 305 lifting crane. This lifting crane makes it possible to raise the safety cable 10 and the fiber optic cable 40 of the maintenance device 1 by means of pulleys.

The system may comprise at least one pulley 311,312 for the safety cable 10, intended to transmit movement to the safety cable 10. A first pulley 311 coupled to the lifting crane 305, allows the lifting movement of the lifting crane 305 to be transmitted to the safety cable 10. Preferably, the first pulley 311 is coupled to the lifting crane 305 by means of a sling 310. A second pulley 312, preferably on the surface at ground level, makes it possible to unwind the safety cable 10 as and when lifting or lowering movements of the lifting crane 305. This second pulley 312 is preferably fixed to the drill head by a sling 313. Thus, the first 311 and the second pulley 312 make it possible to transmit the movements of the lifting crane 305 to the safety cable 10 . The movements of the lifting crane 305 actuate the rotation of the pulleys 311,312 which then allow for the first pulley 311 the transmission of the lifting movement, and for the second pulley 312 the transmission of the lifting movement causing the unwinding of the cable 10 security.

The safety cable 10 can be unwound from a reel 330, coupled to a lifting device 320. The lifting device 320 is preferably a winch. The winch can be motorized or not. It controls the winding and unwinding of the safety cable 10.

The system may also include a pulley 340 for the fiber optic cable 40, intended to transmit movement to the fiber optic cable 40. This pulley 340 can also be coupled to the lifting crane 305. This pulley 340 makes it possible to transmit the elevation movement of the lifting crane 305 to the fiber optic cable 40. Thus, when the lifting crane 305 is set in motion, the rotation of the pulley 340 is actuated, which allows the transmission of the lifting movement of the lifting crane 305 to the fiber optic cable 40.

Furthermore, the fiber optic cable 40 can be unwound from a reel 350 connected to a lifting device 360. This device 360 is also preferably a winch. This winch can be anchored to the ground by means of an anchoring means 370. The winch can also be motorized or not. It controls the winding and unwinding of the fiber optic cable 40. Additionally, the winch may include a turn counting device for unwinding the fiber optic cable. This measures the length of unwound fiber optic cable.

The system may include a fork 380, intended to hold the holding guides 20 and the stops 30 during assembly. The fork 380 can have at least two arms. It can be placed on the head of the well. This fork 380 makes it possible to retain the holding guides 20 and the stops 30 so that the holding guides 20 and the stops 30 do not fall into the borehole by gravity during assembly.

This assembly system 300 saves time for assembling a maintenance device 1 for determining the position of a blocking point 2 of a tubular element 3 . Indeed, this system 300 is quick and easy to implement. In addition, it is easy to use and does not require specific and expensive equipment. In addition, the pulleys allow the cables to be unrolled. In addition, the fork makes it possible to maintain the holding guides and stops which rest on it on the surface in order to prevent the latter from falling by gravity when they are not fixed on the two cables.

According to another aspect, the invention relates to a method 400 for installing a maintenance device 1 for determining the position of a blocking point 2 of a tubular element 3, shown in figure 10 .

Preferably, the maintenance device 1 is initially assembled horizontally relative to the ground, and close to the head of the borehole.

The method may include a step 410 of attaching the holding guides to the fiber optic cable 40. This fixing is preferably fixed and removable between the means 27 for fixing a holding guide 20 and the fiber optic cable 40.

In addition, during this fixing step, the distance between each holding guide 20 may not be determined. Indeed, since the attachment is not yet removable at this stage between the holding guides 20 and the fiber optic cable 40, the distance between each holding guide 20 is not fixed. Furthermore, the fixing means 27, preferably by crushing, of the retaining guides 20 is not activated. Thus, the holding guides 20 are close to each other.

The process, illustrated in figure 10 , may include a step 415 to seal one end of the fiber optic cable 40. Preferably, the end is the end of the fiber optic cable that will first enter the borehole. This makes it possible on the one hand to limit the movement of the fiber optic cable by preventing the fiber optic cable from being released from the attachment means and on the other hand to allow the resistance of the fiber optic cable to environmental pressure conditions , temperature and chemistry of the borehole.

A method in accordance with the invention may comprise a step 420 of coupling the holding guides 20 with the safety cable 10.

This step may also include the assembly of the safety cable 10 with the stops 30. Indeed, each holding guide 20 can be positioned between at least one stop 30. Alternatively each holding guide 20 can be positioned between an upstream stop 30 and a stop 30 downstream. The upstream abutment 30 and the downstream abutment constituting a pair of abutments of the plurality of pairs of abutments. In addition, the system for fixing by crushing each stop may not be activated. This allows the safety cable to slide freely between each stopper and each holding guide.

Such a method can comprise a step 425 of fixing one or more weights to one of the ends of the security cable 10 . Preferably, the end is the end which will penetrate first into the tubular element 3 . In addition, the weight or weights fixed to the safety cable 10 can be close to a stop 30.

A method according to the invention can comprise a step 430 of fixing one of the stops on the safety cable 10 . The stop in the immediate vicinity of the ballast 50 can be fixed on the safety cable 10 by fixing by crushing. Preferably, the stop 30 fixed to the safety cable 10 is the stop in the immediate vicinity of the ballast(s) 50. This makes it possible to maintain all of the stops 30 and the plurality of guides 20 for holding onto the safety cable 10 when it is raised to enter the tubular element 3.

A method in accordance with the invention may comprise a step 440 of elevation by vertical lifting of the entire device 1 for maintenance. Thus, the fiber optic cable 40, safety cable 10, plurality of retaining guides 20, plurality of stops 30 and ballasts 50 can be lifted vertically by the lifting crane 305 . The assembly can be placed at the head of the drill.

Thanks to the simple coupling of the holding guides 20 on the safety cable 10 and of the plurality of stops 30, under the effect of gravity, the holding guides 20 and the stops 30 can slide along the safety cable 10. All of the stops and holding guides can then rest on the single stop fixed to the safety cable, namely, the stop in the immediate vicinity of the weight(s) 50. This facilitates the holding and routing of the device 1 wellhead maintenance.

Still in order to facilitate the maintenance and routing of the maintenance device 1 at the drill head, the fiber optic cable 40 can be placed on the pulley 340 for the fiber optic cable and the safety cable 10 on at least one pulley 311 , 312 for the safety cable. The maintenance device 1 can be raised vertically to a height making it possible to place the weight(s) 50 inside the borehole. The height depends on the length of the maintenance device 1.

Furthermore, in order to maintain the plurality of holding guides 20 and the plurality of abutments 30 which rest on the only abutment fixed to the safety cable, the fork 380 can be placed on the wellhead. This makes it possible to maintain the surface of the holding guides and the stops which therefore rest on the fork. Preferably, the fork 380 is placed under the stop 30 closest to the weight(s) 50 which is fixed to the safety cable 10 .

A method according to the invention may comprise a step 450 of fixing the holding guides to a maintenance device 1 . For this, the method can comprise a step 455 of lowering the maintenance device 1 into the borehole. The descent of the maintenance device 1 can be carried out by means of a logging unit. In addition, the maintenance device 1 can be lowered 10 meters deep into the well. The stop(s) 30 of the holding guide 20 closest to the ballast(s) 50 can then be fixed to the safety cable 10. Furthermore, the fiber optic cable 40 can be fixed to the holding guide 20 by fixing, preferably by fixing by crushing.

Once the stop(s) 30 have been fixed on the safety cable 10 and the holding guide 20 fixed on the fiber optic cable 40, a lowering step 455 can be performed again by the logging unit. The maintenance device 1 is preferably lowered again, for example 10 meters deep into the borehole. The descent of the device depends on the desired spatial resolution, thus the device can be lowered by more or less 10 meters.

The step 450 of fixing the holding guides to the maintenance device can be repeated until all of the plurality of holding guides are fixed to the fiber optic cable.

A method 400 for setting up is quick and simple to implement with a reduced number of steps, and makes it possible to control costs in particular, thanks to the equipment used but also thanks to the reduction in assembly time near the drilling .

According to another aspect, the invention relates to a tubular element 3 comprising a maintenance device 1, preferably arranged inside the tubular element 3, for determining the position of a point 2 of blocking of said tubular element .

A tubular element 3 equipped with a maintenance device 1 can comprise a safety cable 10, a plurality of holding guides 20, a plurality of stops or a plurality of pairs of stops 30 and a fiber optic cable 40. This element 3 tubular makes it possible to determine with precision, reliability and accuracy a blocking point 2. In addition, such a tubular element 3 is secure for use in basements.

As has been presented, the invention makes it possible to determine the position of the blocking point 2 of a tubular element 3 in a secure, rapid and simple manner. Indeed, it is possible to control in a single measurement a hundred meters of tubular element 3. This saves time when implementing the invention. In addition, the measurements are reliable, simple and precise. Furthermore, the invention saves time due to the performance of a single set of measurements, due to its equipment and its installations. In addition, the drilling rig is not immobilized for a long period. The invention is also less expensive due to its equipment and the reduction in the downtime of the borehole. In addition, the invention is particularly secure by all of its equipment and advantageously secure by the absence of an active sensor and therefore without any electrical system or device.

Claims (15)

1. A maintenance device (1) for determining a position of a blockage point (2) of a tubular member (3), comprising a fiber-optic cable (40) and a plurality of holding guides (20), each holding guide (20) being attached to the fiber-optic cable (40) and including an attachment means (21) for attaching to an inner wall of the tubular member.
2. The maintenance device (1) according to claim 1, characterized in that it comprises a safety cable (10), wherein each holding guide (20) is arranged so as to allow a translational movement of the holding guides with respect to the safety cable (10).
3. The maintenance device (1) according to claim 2, characterized in that it comprises a plurality of stops (30), each stop (30) being coupled to the safety cable (10) and to one of the holding guides (20) so as to limit the movement of said holding guide (20) with respect to the safety cable (10).
4. The maintenance device (1) according to claim 2, characterized in that it comprises a plurality of pairs of stops (30), each stop (30) of each said pair of stops being coupled to the safety cable (10) and being positioned on either side of one of the holding guides (20), respectively, so as to limit the movement of said holding guide (20) with respect to the safety cable (10).
5. The maintenance device (1) according to any one of claim 2 to 4, characterized in that each holding guide (20) comprises a conduit (25) formed in the holding guide (20) to accommodate the safety cable (10).
6. The maintenance device (1) according to the preceding claim, characterized in that the conduit (25) protrudes into the holding guide (20) along its entire length and preferably in its center.
7. The maintenance device (1) according to any one of preceding claim, characterized in that the attachment means (21) is selected from: a mechanical attachment means, a magnetic attachment means, an electromagnetic attachment means, a chemical attachment means.
8. The maintenance device (1) according to any one of claim 1 to 7, characterized in that the attachment means (21) for attaching the holding guides (20) allow a fixed and removable attachment to the inner wall of the tubular member.
9. The maintenance device (1) according to any one of claim 1 to 8, characterized in that the attachment means (21) correspond to a magnet, a plurality of magnets, permanent magnets, electromagnets, plasto-magnets, moving members, or combinations thereof, configured to attach to the tubular member (3).
10. The maintenance device (1) according to any one of preceding claim, characterized in that each holding guide (20) comprises a conduit (26) adapted to the fiber-optic cable, for accommodating the fiber-optic cable (40).
11. The maintenance device (1) according to any one of preceding claim, characterized in that the holding guides (20) of the plurality of holding guides are spaced apart from each other by a distance of the order of the size of a section of the tubular member, preferably each holding guide is spaced no more than 20 meters.
12. A system (100) for determining a position of a blockage point (2) of a tubular member (3), characterized in that it comprises a reflectometry distributed measurement device (110) and the maintenance device (1) according to any one of claim 1 to 11, said reflectometry distributed measurement device (110) being connected to the maintenance device (1) and configured to carry out a measurement of deformation of the tubular member (3).
13. A method (200) for determining a position of a blockage point (2) of a tubular member (3) by means of a maintenance device (1) comprising a fiber-optic cable (40) and a plurality of holding guides (20), each holding guide (20) being attached to the fiber-optic cable (40) and including an attachment means (21) for attaching to an inner wall of the tubular member (3), the maintenance device (1) being inserted into the tubular member (3) and the holding guides (20) being attached to the tubular member (3) by means of the attachment means (21), said method (200) comprising:

    - A step (240) of a first reflectometry distributed measurement,

    - A step (250) of stress application to the tubular member (3) or removing a stress applied to the tubular member (3) prior to the step (240) of the first reflectometry distributed measurement,

    - A step (260) of a second reflectometry distributed measurement, and

    - A step (290) for determining the position of the blockage point (2) of the tubular member (3) by comparing the first and second reflectometry measurements.
14. The method (200) for determining a position of a blockage point (2) according to claim 13, characterized in that the first and second reflectometry distributed measurements (240,260) each include calculating Brillouin backscattering in the optical fiber by means of a deformation distributed measurement device (110).
15. A tubular member (3) comprising the maintenance device (1) according to any one of claim 1 to 11 for determining a position of a blockage point (2) of said tubular member (3).

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