MX2008010622A - Method and apparatus for locating a plug within the well - Google Patents

Abstract

The invention provides an apparatus for determining the location and/or the displacement of an object (20) in a wellbore (1), comprising:a reel (40) of wound optic fiber line (10) (or fiber) fixed to the object, and a light transmitter/receiver device (12) able to generate a signal and to measure a change of said signal;wherein the optic fiber line is:on a first position fixed to a reference point linked (4) to the light transmitter/receiver device and is on a second position unwound from the reel. The apparatus can further comprise a sensor and/or an actuator. Accordingly, the invention discloses the associated method to locate an object within the wellbore, the associated method to determine a property of an environment surrounding an object within the wellbore, and the associated method to actuate an object within the wellbore.

Description

METHOD AND APPARATUS FOR LOCATING A SHUTTER INSIDE THE WELL FIELD OF THE INVENTION The present invention generally relates to an apparatus and methods for completing a well. Particularly, the present invention relates to an apparatus and methods for locating a cementing apparatus in the hole of the well, such as a cement sealant. More particularly, the present invention relates to an apparatus and methods for determining the position of the cement plug within the well.

DESCRIPTION OF PREVIOUS TECHNIQUE After a well has been drilled, the normal practice in the oil industry is to line the well with a metallic casing pipe. In this way an annular area is formed between the casing and the formation. Then a cementing operation is conducted in order to fill the annular area with cement. The combination of cement and coating reinforces the well hole and facilitates the isolation of certain areas of the formation behind the lining for the production of hydrocarbons. It is common to use more than one string of casing in a well hole. In this regard, a first string of casing pipe fits into the well hole when the well is drilled to a designated first depth. The first string of casing is hung from the surface, and then the cement flows into the ring behind the casing pipe. The well is then drilled to a second designated depth, and a second casing string, or liner, is run into the well. The second string is adjusted to a depth so that the upper portion of the second casing string exceeds the lower portion of the first casing string. The second string is then fixed or hung from the existing casing. After this, the second string of casing is also cemented. This process is normally repeated with additional lining strings until the well has been drilled to full depth. In this way, the wells are normally formed with two or more casing strings of a diameter that always decreases.

The process for cementing a liner in a well hole typically involves the use of liner cleaning shutters and drill pipe darts. The shutters typically define an elongated elastomeric body used to separate the pumped fluids into the wellbore. A liner cleaner seal is typically located within the top of a liner, and is lowered into the well hole with the liner at the bottom of a work string. The liner cleaner plug has radial cleaners that contact and clean the inside of the liner as the plug travels down the liner. The coating cleaner plug has a cylindrical hole through it to allow the passage of fluids.

Normally, the cementing operation requires the use of two shutters and darts. When the cement is ready to be dispatched, a first dart is released to the work string. The cement is pumped behind the dart, thus moving the dart well down. The dart acts as a barrier between cement and drilling fluid to minimize cement contamination. As the dart travels downstream it sits against a first coating cleaner plug and closes the internal hole through the first plug. The hydraulic pressure of the cement above the dart forces the dart and the shutter to be dislodged from the liner and pumped down the liner together. At the bottom, the first plug sits against a float valve, thereby closing the flow of fluid through the float valve. The pressure increases on the first shutter until it is sufficient to cause the rupture of a membrane in the first shutter. Thereafter, the cement flows through the first plug and float valve and up into the annular space between the well hole and the liner.

After a sufficient volume of cement has been placed in the well hole, a second dart is deployed. The drilling mud is pumped back from the second dart to move the second dart under the work string. The second dart travels down the pit and sits on a second coating cleaner shutter. The hydraulic pressure above the second dart forces the second dart and the second shutter dislodges the liner and is pumped together under the liner. This forces the cementation head of the second plug to move out of the liner and into the ring. This displacement of cement towards the ring continues until the second plug sits against the float valve. Thereafter, the cement is allowed to cure before separating the flotation valve.

The cementing operation may also need the use of a simple shutter and dart; The first shutter or dart of the preceding operation is separated.

During the cementing operation it is desirable to know the location of the second plug / dart in the well hole, or at least its movement in the wellbore. In general, the position of the plug will indicate the amount of cement that has moved towards the ring. If insufficient cement has been displaced (called "sub-displacement"), the cement will remain in the sheath. If too much cement has been displaced (called "over displacement"), part of the ring will not be cemented.

One method for determining the location of the obturator is by measuring the displaced volume after the second obturator is released. Then, the displaced volume is compared to the displacement volume calculated based on the dimensions of the casing or drill pipe. The drawback of the displacement method is that it is not very accurate and does not give a positive indication that the shutter is moving at the same speed as the fluid that is pumped behind the shutter. The casing and drill pipe are generally manufactured to dimensional tolerances that can result in a substantial difference between the calculated displacement volume and the actual displacement volume. In addition, the fluids are subject to aeration and compression during the operation, thus affecting the volume measured.

Another method is to join an indication wire to indicate that a shutter has been released. The indication wire is generally 2 to 3 feet long. Another method uses a mechanical fin gauge. In this method, a lever is placed under the pack of the shutter. A released shutter will change the lever when the shutter travels through it. The drawback is that the wired indicators and fin mechanical indicators only indicate that the shutter has been released, and not the location of it.

Another method is to use electromagnetic or magnetic signals. In general, an identification tag is attached to the shutter or dart. A detector located below the cementation head peaks picks up the signal when the shutter passes to indicate that the shutter has been released. The problem is that the signal detectors can not track the shutter for long distances and only indicate that the shutter has moved past the detection device.

Another method is described in patent US6634425. A cementing shutter with a sensor transmits the measured value to the surface by means of wired or wireless transmission means, such as: wired cable, optical fiber or acoustic waves. The problem is that the cementation plug can not be deployed for large distances.

Another method is described in the patent application US20040060697. Although the system is an improvement in the method for locating a plug in the wellbore, the system is insufficient because it still applies to an "indication wire" method. An optical fiber is used to locate the obturator. The optical fiber is provided with markings to facilitate the reading of the dispatched length. Alternatively, one or more rollers can be dispensed under the dispensing device. As the fiber is dispensed, it will cause the roller to rotate at the respective distance. The length of the dispatched fiber is calculated from the number of revolutions made by the roller. The problem to read the position of the obturator thanks to the unfolded length of the fiber is not that exact because in the operation, the fiber can lengthen or strain under the weight of the obturator or the drilling mud behind the obturator. Also, patent application US20040060697 describes a correction method for this drawback where the fiber optic line may be equipped with one or more sensors to provide a more accurate indication of the location of the dart. A simple different sensor is placed on the fibers near the dart. The dart travels in a running string and is coupled to a dispatcher placed on the surface. An optical signal sent from the surface must travel the full distance along the fiber to reach the sensor. Normally, the distance can be determined by measuring the total time required for the signal to travel from the optical signal source to the sensor and then to the receiver. Because the total length of fiber and the amount of fiber dispensed are known, any elongation of the fiber due to stress can be adequately counted. As a result, the location of the dart is determined in real time. The problem is that the method calls for a complex deployment of difficult measuring devices and processes: the fiber roller with markings, the transmitter / receiver on one side, the sensor on the other side.

In addition, the patent US6561488 describes a method for deploying a cable in a pipe, avoiding greater inconvenience of the conventional deployment technique, suppressing the problem of effort in the process to unwind the fiber. However, the patent US6561488 is not interested in the measurement of the position of the obturator. The patents GB2119949 and WO02082151 also describe similar methods.

Therefore there is a need for an easy apparatus to locate a shutter in the wellbore. In addition, there is a need for an apparatus for determining parameters informing about the setting of the cement.

COMPENDIUM OF THE INVENTION According to one aspect of the invention, the invention provides an apparatus for determining the location and / or displacement of an object in a well hole, consisting of: a spool of fiber optic line wound (or fiber) attached to the object, and a light transmitting / receiving device capable of generating a signal and measuring a change of the signal when it occurs in a second position; wherein the fiber optic line is: in a first position fixed to a reference point attached to the light transmitting / receiving device, and is in a second position unrolled from the spool. The reel is fixed directly to the object or by means of a housing. The transmitter / receiver of light is a transmitter / receiver not only limited to visible light, other electromagnetic radiation including ultraviolet radiation (near UV (380-200 nanometer wavelength), and / or distant UV or vacuum (200-10 nanometers, FUV or VUV), and / or extreme UV (1-31 nanometers, EUV or XUV)) and infrared radiation (preferably: Band-0 1260-1360 nanometers; and / or E-band 1360-1460 nanometers; or S-Band 1460-1530 nanometers; and / or C-Band 1530-1565 nanometers; and / or L-Band 1565-1625 nanometers; and / or U-Band 1625-1675 nanometers) are contained in the transmitter / receiver of light. The reel unrolls under the movement of the object. By means of this principle, two points define the reference point corresponding to the first position and a dynamic point corresponding to the second position or to the location of the dynamic object. Therefore, the apparatus can measure a position of the dynamic object (depth) or a movement movement of the dynamic object (speed, acceleration). The reference can be static or dynamic; The importance is to know where this point of reference is. The main advantage of this technique is the ability to locate the object from a single fiber end; The reference.

The light transmitting / receiving device is an apparatus capable of measuring the change of the signal in the second position. Effectively, there is no need to measure a signal change along the entire fiber optic line; the only interesting change informing of the location or displacement of the dynamic object is in the second position. The change of signal can be done thanks to an optical episode, such as a modification of the morphology of the fiber optic line, more precisely a fold in the fiber optic line. There is a way to strengthen the optical episode. Firstly, the reel can have a winding diameter or a curvature in the reel short enough to create a bend in the second position producing the signal change in the second position. Secondarily, an additional element can be added in the second position to create a fold in the second position also producing the signal change in the second position. All these advantageous modalities ensure that the important optical episode is located in the second position and is detected more precisely.

Preferably, the light transmitting / receiving device is an apparatus of the family of time domain optical reflectometers (ODTR). Indeed, the reflectometer will inject a short but intense light pulse towards the fiber optic line from the first position and measure the backscattering and reflection of light as a function of time. The fold created in the second position will ensure an attenuation that will be detected by the reflectometer. Preferably if it needs to be cost effective, this light transmitting / receiving device is a fiber breaking locator (FBL), which is approximately a simplified reflectometer designed to detect only breakage along the fiber.

The apparatus of the invention is applied to objects such as a dart or a shutter. The spool has a diameter between 20 and 50 millimeters, and preferably between 30 and 35 millimeters for a light pulse wavelength of 1310 or 1550 nanometers.

According to another aspect of the present invention, the apparatus can be deployed with one or more sensors informing the property of the environment surrounding the sensor. Also, the fiber optic line is attached to a sensor located on the object. Indeed, because the fiber is already deployed between the surface and the object, a signal can be transmitted along the fiber from the surface to the sensor and from the sensor to the surface. This second mode is compatible with the location apparatus: for location, the light transmitting / receiving device focuses only on the fold in the second position; for the sensor, the light transmitting / receiving device uses all the fiber to transmit and receive signal from the sensor. The object can have all kinds of associated sensors and electronics including energy suppliers to measure the physical parameters of the environment: temperature, pressure, pH, salinity, density, resistivity, or conductivity. For example, when the object is a shutter, the sensor may be an ultrasonic needle to measure the wait in the setting of the cement (WOC).

More preferably, the sensor is a self sufficient energy sensor. The associated electronics are small and with low consumption: a sensor with limited volume and limited energy supply allows a minimum volume. For example, the sensors can be of the MEMS type. More preferably, the sensor is self-sufficient in terms of power supply. For example, the sensors may be of the optical sensor type; When an optical signal is sent to the optical sensor, the signal reflected by the sensor informs about the measured physical parameter. For example, the sensor is a * temperature sensor and / or a pressure sensor from the family of Bragg grid sensors. The biggest advantage is that there is no need for complex or unmanageable electronics or power supply 'to support the sensor. All electronics and analyzer parts are on the surface, a signal is sent from the surface to the object and to the embedded sensor, the reflected signal received on the surface is analyzed and reports on the physical parameter measured in the vicinity of the sensor on the object. For example, the object is a shutter containing an embedded Bragg grid sensor informing about the temperature of the cement as a function of time, thanks to the function of the temperature profile of the time the WOC can be measured.

According to another aspect of the invention, the apparatus can be deployed with one or more activators to be activated in the object.

The invention also provides a method for determining a location and / or a displacement of an object in the well hole, which consists of: (i) attaching an optical fiber line spool wound on the object; (ii) fix the fiber optic line in a first position to a reference point; (iii) moving the object so that the fiber optic line is unwound from the spool in a second position; (iv) generating from the first position a signal along the fiber optic line; (v) measuring from the first position a change of the signal along the fiber optic line where this change of the signal reports on the second position; and (vi) deduce from this change the location and / or displacement of the object. The measurement can be made when the object is in motion or is in a static position.

Preferably, the method also contains fixing means capable of creating the signal change in the second position. Preferably also, the method further contains the step for generating from the first position another or more signals along the fiber optic line.

In another embodiment, the method further contains the step of (i) fixing on the object, means for detecting the property of the environment surrounding the object and the means for detecting are attached to the fiber optic line; and (ii) deduce from the change of the signal the property of the environment surrounding the object. Preferably, at least two signals are generated from the first position, and the measured change of one signal reports on the second position and the measured change of another signal informs about the property of the environment surrounding the object.

In yet another embodiment, the method further contains the step of (1) attaching to the object, means for activating the object and the activation means are attached to the fiber optic line; and (ii) generating from the first position a second signal along the fiber optic line to activate the object.

The invention also provides a method for determining a property of an environment surrounding an object in a well hole, which consists of: (i) attaching an optical fiber line spool wound on the object; (ii) fixing on the object means for detecting the property of the environment surrounding the object and the detection means are attached to the fiber optic line; (iii) fixing the fiber optic line in a first position to a reference point; (iv) moving the object so that the fiber optic line is unwound from the reel to a second position; (v) generating from the first position one or more signals along the fiber optic line; (vi) measuring from the first position a change in the one or more signals; and (vii) deduce from this change the ownership of the environment surrounding the object and the location of the object.

BRIEF DESCRIPTION OF THE DRAWINGS Other embodiments of the present invention can be understood with the attached drawings: Figure 1 shows a schematic diagram showing the apparatus in a first embodiment according to the invention. Figure 2 shows a schematic diagram showing the apparatus in a second embodiment according to the invention.

DETAILED DESCRIPTION Figure 1 is a view of the apparatus deployed in a coated well bore 1. A shutter 20 is shown moving along the well bore thanks to a well hole fluid such as drilling mud which is pumped behind the shutter . This plug separates the cement from the drilling mud to minimize cement contamination. As the plug moves along the wellbore, the cement in front of the plug is displaced into the wellbore.

A fiber optic line 10 or fiber that is wound on a spool 40 is attached to an upper part of the shutter; practically the spool is attached or fixed through a single hanging point 5 corresponding to one end of the fiber or through a part of the spool. The reel may also be mounted in a housing or cartridge. The importance is that when the shutter moves along the wellbore, the spool and the shutter are interdependent, but the fiber can be unwound from the spool. At the other end of the fiber, the fiber is attached or fixed to a first position 4, or to a reference point. As it is understood, the fiber is unwound from the reel solely by the movement of the obturator to a second position 4", which corresponds to a dynamic point.A upper part 10A of the fiber corresponds to the unwound fiber (between the first position and the second position) and a lower part 10B of the fiber corresponds to the wound fiber, still on the reel.The dynamic point against the reference point or the second position against the first position informs of the location of the shutter inside the well or on the speed of the shutter movement inside the well.

An advantage of using fiber optic line 10 is its size, because it can be easily installed inside the shutter and contradictorily its fragility, because it can be destroyed easily after the cementing job has finished, for example with a drilling tool or because it will not damage any other expensive tool. In general, fiber has a smaller external diameter than other wire products such as wireline cable. In that way, any fiber remaining in the well hole can be easily drilled, thereby minimizing any problems associated with materials left in the wellbore. Additionally, fiber optic lines are tolerant to high temperatures and corrosive environments when protected by their protective coating, and thus have wide application in the oil industry. The fiber optic line used can be any type of optical fiber, multi-modal or simple mode. Preferably if it is needed to be cost effective, the fiber optic line is used in a simple way.

The spool 40 of the wound fiber optic line is made in such a way that the winding of the fiber ensures that the fiber can be unrolled in a simple manner from the spool with a minimum tension applied to the spool of the fiber. By unwinding the spool from the shutter in place from the surface, the fiber unfolds without any movement into the wellbore. In this way, the only mechanical force applied to the fiber is a drag force that comes from the flow of the drilling mud; there is no additional tension. The winding has to consider that the unwinding can be operated at low or high speed, with low or high density for the surrounding fluid. Also an important parameter to consider is the path that the fiber will use when unrolling. The wound fiber optic spool is made in such a way that the winding of the fiber ensures that the deployed fiber has a known path or curve. The torsion of the fiber in the reel and the winding are chosen accordingly. Indeed, as shown in Figure 1, the path of the fiber 10 is rectilinear or substantially rectilinear in the part 10A. The trajectory, such as a helix with known radius and vertical separation, can also be used. The path can also be chosen so that the fiber touches the wall of the well hole: The radius of the propeller is larger than the radius of the well hole. Other more complex trajectories can also be chosen. Thanks to the advantageous properties of fiber, size and weight, this trajectory will not be changed inside the well hole, during unwinding or sometimes after unwinding.

In addition to the manner in which the fiber is wound and the curve of the latter, an additional means can be used to fix or stick the winding of the fiber, a special glue, a physical or chemical treatment of the fiber. Also, the fiber can be further treated so that it is chemically resistant and able to stop the high abrasion of solid particles flowing at high speed into the wellbore for a certain period of time (usually 12 hours). For that purpose, the fibers can be specially treated or they can be packed inside a protective jacket. Additionally, the reel may be associated with a housing or a dispenser cartridge that supports the winding of the fiber. The housing or the cartridge can be directly attached or fixed to the obturator.

The first position 4 is located inside a head for cementation 3, which is a static point. From this first position the fiber is connected to a light transmitting / receiving device 12 by means of a supply duct: the low pressure is connected to the device 12 and the high pressure is connected to the fiber optic line 10. The transmitting device / light receiver is an Optical Time Domain Reflectometer (OTDR). The OTDR is an instrument that analyzes the light lost in a fiber. The working principle consists in injecting an intense, short laser impulse towards the fiber and measuring the backscattering and reflection of light as a function of time. The reflected light is analyzed to determine the location of any fiber optic episode such as splices, extreme fiber breakage. In a simpler design often defined as a Fiber Breaker Locator (FBL), functionality is limited to the distance measurement of the first large optical episode. Preferably, the light transmitting / receiving device 12 is an FBL.

A characteristic of the fiber is known with sufficient precision to calculate the length of the unfolded fiber (Part 10A) or the entire length of the fiber (Parts 10A and 10B). For example, the fiber index is known, n = 1.4752. As the obturator moves out of the head for cementation, the movement of the obturator unwinds the fiber. The fiber deployed inside the well hole does not present any particularity that could considerably attenuate the propagation of the optical impulse (Part 10A). By creating an optical episode at the shutter level corresponding to the second 4 'position, the FBL will give the actual position of the shutter.

In a first embodiment, the reel is made with a short curve diameter or more precisely a short diameter sufficient to be detected by the FBL (critical diameter dc or critical radius rc > = dc); indeed the short diameter creates a detectable attenuation by the FBL. The diameter of the spool is sufficiently short to stop the propagation of the optical impulse. The diameter of the spool capable of stopping the optical pulse is a function of the pulse wavelength. Since the reel is seen as the first major optical episode, the FBL will measure the length of the fiber deployed to the reel, that is, the obturator. However, also the spool diameter can not be too short; By effectively reducing the diameter of the reel, you can limit the maximum distance that can be measured to an unacceptable value.

In a second embodiment, the reel has been specially modified so that the reel has a minimum required curvature short enough to be detected by the FBL. In this way, the reel can have various geometric shapes; the important thing is that within the various curvatures present is this reel, there is a minimum curvature (close to rc) which is the sufficiently short curvature required to be detected by the FBL. For example, the shape of the spool can be ovoid with a desired curvature. The desired curvature is short enough to stop the propagation of the optical impulse. The desired curvature capable of stopping the optical pulse is a function of the pulse wavelength.

In a third embodiment, the reel is made with a diameter not necessarily short but large, incapable of stopping the optical impulse and using the method described above. In this case, an additional element (not shown in the Figure) is added in the second position 4 '. The additional element corresponds to the mechanical path through which the fiber is unwound and bent into a radius short enough to stop the optical impulse. In fact, the additional element creates the optical episode. The additional element may simply be an angled tube or an angled collar through which the fiber passes. The radius capable of stopping the optical impulse is a function of the pulse wavelength. All these advantageous modalities ensure that the main optical episode is located in the second position and is detected more precisely.

In a fourth embodiment, the fiber is wound as in the second embodiment at a constant radius and large R, which is greater than the critical radius rc but with a truncation at G greater than 1 (the truncation of 1 corresponds to the joined turns ). As a consequence, the layers of even and odd fibers are trapped and an optical episode is created at each crossing of the fibers of successive layers. The fiber diameter is small compared to the winding diameter, it can be easily established that the folded radius of the fiber created by the crossing of two fibers is an inverse function to the rolled truncation T which can take any integer value greater than zero: rCrossing R / T For example, a coil diameter of 30 mm with a truncation of 3 has the same optical response as a coil of wound radius 10 of the first embodiment. As for the second modality, the optical episodes are evenly distributed along the fiber. The distribution period being less than the OTDR length resolution, the coil manufacturing process does not alter the measurement resolution.

The key advantage of this technique is the possibility of performing this analysis from a single fiber end: the measurement is carried out from the surface without any expensive downhole equipment that can be destroyed when drilling operations continue once the cement forge.

The fibers are able to withstand a relatively high tensile force, but they become very fragile once the fiber jacket is damaged. It is important to consider a method to detect fiber breakage. If fiber breakage occurs in part 10A (at a shorter distance than previously measured), the fiber is undoubtedly broken. If the breaking of the fiber occurs in part 10B, it is impossible to make a priori difference between a derived obturator and a broken fiber. A first solution to detect fiber breakage is to analyze the received signal and the attenuation. Indeed, the characteristic attenuation that occurs for a "fictitious" optical episode, as described above (short spool diameter, reel curvature, additional element creating the bend or curvature) is different from an attenuation that occurs for a fiber break. This characteristic attenuation will report the breakage or not of the fiber.

A second solution is to assume that one can measure the true fiber length by including its wound part simultaneously with the position of the shutter. The solution consists in using two wavelengths, for example 1550 nanometers and 1310 nanometers. At the longest wavelength the reel generates a large attenuation while the shorter reel becomes almost transparent. In this way, the fiber length measured at the largest wavelength is the distance between the first position and the second position; while the fiber length measured at the shortest wavelength is the true fiber length. The comparison of both measurements is an ambiguous way of making the difference between a non-moving obturator and a broken fiber.

One aspect of the apparatus is that it can make it possible to determine an absolute or relative location of the obturator. Indeed, as stated above, the fiber curve ensures that the deployed fiber (part 10A) has a known path or curve and the FBL measures the length of the fiber deployed to the shutter. When the trajectory is rectilinear, there is a direct correlation between the length of the fiber deployed from the surface to the obturator and the depth of the obturator from the surface to the obturate, an absolute position of the obturator can be given. In the same way, the length of the fiber deployed from one position to a second reports the relative position of the obturator from this first position to the second. When the trajectory is a more complex helix or curve, there is a link between the length of the fiber deployed from the surface to the obturator and the depth of the obturator from the surface to the obturator, an absolute position of the point can be given. For example for a z-axis propeller, where 1 is the length of the unfurled fiber, z the depth or axial position, r is the radius of the helix and p is a constant giving the vertical separation of the helix loops. In the same way, you can define a relative position. The key advantage for this technique is the possibility of obtaining the actual position or depth of the obturator.

Another aspect of the apparatus is that it can allow the determination of a displacement of the shutter. Indeed, as mentioned above, the winding of the fibers ensures that the deployed fiber (part 10A) has a known path or curve and the FBL measures the length of the fiber deployed to the shutter. Therefore, a speed or an acceleration of the shutter can be determined as a function of time or depth function.

People who have experience in the technique, who perform cement work, will also appreciate the use of this method even when the accuracy of the position is not accurate. Indeed, for cementing work, the exact location is not necessary, an accuracy of 1 meter is exaggerated, 10 meters is excellent and 100 meters is sufficient. It is understood that even if the trajectory of the deployed fiber is changed or modified slightly within the wellbore, it will have a low impact on the carburizing work because it only matters whether a shutter is in a certain area or not. This method is a great benefit. Also, for cementing work, sometimes no location is needed, but rather the arrival of the obturator to a certain position where it stops or falls slowly. In this way, information on the relative speed of the shutter is sufficient. In this way, the method is also a great benefit.

Figure 2 is a view of the apparatus deployed in a well hole with casing 1 with a slight improvement: the apparatus is deployed with one or more sensors informing about the property of the environment surrounding the obturator, such as cement. All the features already described for Figure 1 are also applicable. A shutter 20 is shown moving along the wellbore thanks to the wellbore fluid such as the drilling mud that is pumped behind the plug. A fiber optic line 10 or fiber that is wound on a spool 40 is attached to an upper part of the shutter. The spool 40 comprises an end of the fiber 5 which is attached to a sensor 50 located in the shutter. The sensor may or may not be in contact with the cement. At the other end of the fiber, the fiber is attached or fixed to a first position 4, or to a reference which also corresponds here to a static point. As it is understood, the fiber is unwound from the spool thanks to the movement of the shutter to a second position 4 ', which corresponds to a dynamic point. An upper part 10B of the fiber corresponds to the unwound fiber (between the first position and the second position) and a lower part 10B of the fiber corresponds to the wound fiber, still on the reel.

The first position 4 is located inside a cementing head. From this first position the fiber is linked to an Optical Time Domain Reflectometer (OTDR) or to a Fiber Breaker Locator (FBL). As the obturator moves out of the cementation head, the movement of the obturator unwinds the fiber. The length of fiber deployed within the wellbore has no particularity that can stop the propagation of the optical pulse (Part 10A). By creating an optical episode at the level of the shutter corresponding to the second position 4 ', the FBL will give the length of the fiber deployed to the obturator.

In the first position 4, at least two signals, each made of a different wavelength, are injected into the fiber. The longest wavelength is attenuated by the first major optical episode created by any of the aforementioned techniques (short reel diameter, reel curvature, additional element creating bending or curvature). The shortest wavelength propagates to the end of the fiber. The travel time of the long wavelength gives the measurement of the length of the fiber deployed to the obturator while the shorter one can access the sensor embedded within the obturator. The sensors embedded inside the obturator will give the possibility of monitoring the parameters measured during the displacement and during the waiting time of setting of the cement (WOC). More precisely, the parameter to measure during these phases of cementation of the well is the temperature. During the movement of the obturator, a convenient way is to evaluate the temperature simulations. During WOC, it will be detected that the temperature increases due to the exothermic reaction of the setting of the cement.

The sensor 50 is an optical sensor of the Bragg grid sensor type. The Bragg grid sensors are made by modulating the refractive index of an optical fiber line around its nominal value. They act as selective reflectors for the Bragg wavelength ?? defined by the following relation: ?? = 2.?.?; where n is the refractive index of the fiber and A is the wavelength of the modulation index. A being a linear temperature function, measuring the Bragg wavelength ?? It is a convenient way to measure the Bragg grid temperature normally to one degree Celsius. The key advantage of this technique is the fact that the measurement is performed remotely at the end of the fiber located on the surface (first position 4). You do not need anything more than the Bragg grid sensor and the level of the shutter where the temperature measurement is made.

Many other physical parameters can be measured using a miniaturized self-sufficient energy sensor. The associated electronics are small and with low consumption: a sensor with limited volume and limited power supply allows a minimum volume. For example, the sensors can be of the MEMS type. The sensor can also be self sufficient in terms of power supply, such as for example an optical sensor there is no need for conventional and expensive packages including electronics, power supplies and analyzer devices. For example, Bragg grid sensors can also be used for pressure measurement.

In another embodiment, multiple optical sensors can be arranged in a network or serial configuration with individual sensors using time division multiplexing or frequency division multiplexing, those sensors can be deployed within the shutter or also along the fiber . When using Bragg grid sensors there is no need to use multiplexers; The multiple Bragg grid sensors are arranged in series network, each Bragg grid sensor has its wavelength and is interrogated by means of the light transmitter / receiver. The objective of deploying the sensors along the fiber can provide a measurement profile in the wellbore. Also, the sensor network can provide an increased spatial resolution of temperature, pressure, stress, or data flow in the wellbore.

The present invention has been described for an obturator in the case of a cementing job, where it is important to define the location of the obturator and / or WOC information. Other applications of the apparatus and the method according to the invention include attaching the wound fiber spool to any type of object moved within the well, such as, for example, punching gun, recoverable packer or any type of tools moved within the well, such as for example a drilling tool, a tool for recording, a logging tool during drilling, a measuring tool during drilling, a test tool, any type of tool hung by a drill pipe, a wired wire, a rolled pipe. Other applications of the apparatus and the method according to the invention include fixing the first position at any static or dynamic point, for example in underwater or downhole operations.

In another aspect, the fiber can be used to transmit signals to a downhole apparatus to effect operation thereof as an operator or an activator. In one embodiment, a fiber optic line may be placed along the wellbore. Thereafter, the signals can be transmitted through the fiber to operate a valve or to activate a sleeve for example. From the surface, at least two signals, each made of a different wavelength, are injected into the fiber. The longest wavelength is reflected by the first important optical episode created by any of the techniques described above (bending made with the reel or bending made with an additional element). At the same time, the shortest wavelength propagates to the end of the fiber. The travel time of the long wavelength gives the measurement of the position of the obturator while the shorter one can have access to the activator inside the obturator. The activator can be self-sufficient, being activated only by the wavelength or it can also be connected to the electronics and energy provider to ensure that this action is carried out.

Claims (1)

1. CLAIMS An apparatus for determining the location and / or displacement of an object (20) in a well hole (1), consisting of: - a reel (40) of a coiled fiber optic line (10), and - a device transmitter / light receiver (12) capable of generating a signal through the fiber optic line (10) and measuring a signal change; wherein the fiber optic line (10 = is fixed in a first position (4) to a reference point and unrolled from the reel to a second position (4 '), the apparatus is characterized by the fact that; - the spool (40) is fixed to the object; - the reference point is connected to the light transmitting / receiving device (12); and - the light transmitting / receiving device (12) is capable of measuring the field of the signal when it occurs in the second position (4 ') · The apparatus according to claim 1 further contains an additional element in the second position (4 ') capable of creating the change of the signal in the second position (4'). The apparatus according to claim 1 or 2, wherein the light transmitting / receiving device is an apparatus of the time domain optical reflectometer family. The apparatus according to claim 3, wherein the light transmitting / receiving device is a fiber breaking locator. The apparatus according to any one of claims 1 to 4, wherein the object is made of a dart or a soft or cleaning ball or plug. The apparatus according to any of claims 1 to 5, wherein the fiber optic line is further attached to a sensor (50) located on the object. The apparatus according to any of claims 1 to 6, wherein the fiber optic line further contains a sensor (50) located anywhere in the fiber optic line. The apparatus according to claim 6 or 7, wherein the sensor is a self-sufficient sensor in energy. The apparatus according to claim 6 or 7, wherein the sensor is a temperature and / or pressure sensor of the family of Bragg grid sensors. The apparatus according to any of claims 1 to 9, wherein the fiber optic line is further attached to an activator (50) located on the object. A method for determining a location and / or displacement of an object (20) in a well hole (1) consisting of: (i) fixing a reel (40) of coiled fiber optic line (10), (ii) fixing the fiber optic line in a first position (4) to a reference point; (iii) moving the object so that the fiber optic line is unwound from the reel to a second position (4 '); (iv) generating a signal along the fiber optic line; (v) measuring a signal change along the fiber optic line; and (vi) deduce from the change the location and / or displacement of the object; the method being characterized by the fact that: - the spool (40) is fixed to the object; - the signal is generated from the first position; - the change of the signal is measured from the first position and the change of the signal informs on the second position (4 '). The method according to claim 11 further contains fixing means capable of creating the change of the signal in the second position (4 '). The method according to claim 11 or 12 further comprises the step of: (i) fixing on the object, means for detecting (50) the property of the environment surrounding the object and the means for detecting are attached to the fiber line optics; and (ii) deduce from the change of the signal the property of the environment surrounding the object. The method according to any of claims 11 to 13 further comprises the step of generating from the first position another or more signals along the fiber optic line. The method according to claim 14, wherein at least two signals are generated from the first position, and the measured change of one signal informs about the second position (4 ') and the measured change of another signal informs about the property of the environment that surrounds the object. The method according to any of claims 11 to 15, further comprises the step of (i) fixing on the object means for activating the object and the means for activating are attached to the fiber optic line; and (ii) generating from the first position a second signal along the fiber optic line to activate the object.