EP3051057A1

EP3051057A1 - A cementing apparatus and system for cementing a wellbore

Info

Publication number: EP3051057A1
Application number: EP15290020.5A
Authority: EP
Inventors: Jean-Louis Pessin
Original assignee: Services Petroliers Schlumberger SA; Schlumberger Holdings Ltd; Schlumberger Technology BV
Current assignee: Services Petroliers Schlumberger SA; Schlumberger Holdings Ltd; Schlumberger Technology BV
Priority date: 2015-01-30
Filing date: 2015-01-30
Publication date: 2016-08-03

Abstract

A cementing apparatus for mixing concrete in a wellbore, the cementing apparatus being intending to be lowered into a wellbore and comprising :
- a first tank (124), intended to receive at least a first component of a concrete,
- a second tank (126), intended to receive at least a second component of a concrete,
- a mixing device (128) comprising at least two inlets (131, 132) respectively connected to the first and second tanks for mixing the first and second components, and an outlet (138),
- a triggering device (130) for triggering at least the entry of one of the first and second component into the mixing device, upon reception of a signal coming from the surface, the wellbore or the formation.

Description

BACKGROUND

During the life of a well, after the casing has been set and the well has been cemented, it may be useful to set concrete in the well, for instance for repairing the walls of the wellbore, for obturating perforations of the casing and/or for plugging the well before abandoning it.
Normally, in such operations, concrete is mixed at surface of the well and conveyed at the bottom of the well with additives that may help delay its solidification. These techniques may sometimes lack precision.

SUMMARY

The disclosure relates to an apparatus, system and method for cementing a wellbore and more particularly mixing the concrete downhole.
The cementing apparatus for mixing concrete in a wellbore is intended to be lowered into a wellbore. It comprises :

a first tank for receiving a first component of a concrete,
a second tank for receiving a second component of a concrete,
a mixing device comprising two inlets respectively connected to the first and second tanks for mixing the first and second components, and an outlet,
a triggering device for triggering the entry of one of the first and second component into the mixing device, upon reception of a signal coming from the surface, the wellbore or the formation.

The mixing device may be an eductor.
A valve may be positioned between the outlet of one of the tanks and the inlet of the mixing device. A valve may be positioned between the outlet of each of the tanks and the corresponding inlet of the mixing device. An additional valve may connect one of the tanks to the outside of the lower assembly.
The triggering device may trigger the opening of one of the valves, or each of the valves.
One of the tank may comprise a piston, the apparatus comprising a motor for moving the piston into the tank, and the triggering device may trigger the operation of the motor.
The first component may be a cement slurry and the second component may be a gas, such as nitrogen or a liquid, such as water. The first or second component may comprise additives. When the second component is a gas, the resulting concrete is a foam concrete which expand when mixed and does require a small volume of first and second components for performing a job.
The triggering device may be connected to a receiver configured to receive electric or electromagnetic signals coming from the surface, the wellbore or the formation. Such a receiver may receiver signals via a slickline cable conveying the lower assembly comprising the cementing apparatus into the wellbore.
The disclosure also relates to a cementing system comprising a lower assembly comprising the cementing apparatus as defined hereinabove and a slickline cable for conveying the lower assembly into the wellbore.
The cementing system may comprise a communication module including the slickline cable and configured to transmit electrical signals between the surface and the lower assembly, and an emitter positioned at surface for emitting the predetermined signal. The emitter may send the predetermined signal upon completion of a monitored criterion. The system may also comprise a measurement unit of at least a parameter at the surface, such as a length of the slickline cable deployed into the wellbore, the criterion being completed if the value of the parameter is in a predetermined range of values.
The disclosure also relates to a cementing method comprising :

lowering a cementing apparatus as defined hereinabove,
receiving a predetermined signal by the triggering device,
triggering an element of the cementing apparatus so that the first and second components enter the mixing device,
mixing the concrete from the first and second component,
depositing the mixed concrete in the wellbore.

Depositing the mixed concrete may comprise forming a plug in the wellbore or closing perforations of the casing or repairing the cement of the wellbore.
The method may comprise isolating a cementing zone from the rest of the wellbore after receiving the predetermined signal. The isolating may take place before triggering the cementing apparatus.
The method may comprise detecting if the apparatus is at a predetermined position, and sending the predetermined signal when the apparatus is at the predetermined position. Detecting if the apparatus is at a predetermined position may include measuring the length of a cable conveying the lower assembly. The method may also comprise sending a predetermined signal from the surface via a communication module comprising the cable conveying the lower assembly into the wellbore. The sending may occur upon detection of the predetermined position.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

FIG. 1 is a drawing of a system for cementing the wellbore according to an embodiment of the disclosure,
FIG. 2A & B are schematic drawings of an example of a lower assembly according to an embodiment of the disclosure, respectively during conveyance and cementing operations;
FIG. 3 is a flow chart of a method for cementing a wellbore according to an embodiment of the disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, some features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would still be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present disclosure, the articles "a," "an," and "the" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
An intervention system 10 according to an embodiment of the disclosure is illustrated in Fig. 1. This system 10 is intended to perform operations in a fluid production or injection well 12 made in the subsoil 14.
These operations are applied by means of a lower assembly for carrying out actions and/or perform measurements at the bottom of the well 12, such as perforations, cuttings by means of a torch, cementation operations, jarring operations or further operations for setting tools into place such as setting into place a seal gasket or anchoring of a tool. In the present case, the lower assembly comprises a cementing apparatus, which will be described in more details later, and the intervention system is used as a cementing system.
These interventions are carried out in any point of the well 12, from the surface 16.
The fluid produced in the well 12 is for example a hydrocarbon such as petroleum or natural gas and/or another effluent, such as steam or water. for instance if the well is an "injector" well into which liquid or gas is injected.
The well 12 is made in a cavity 18 positioned between the surface 16 of the ground and the fluid layer to be exploited (not shown) located in depth in a formation of the subsoil 14.
The well 12 generally includes an outer tubular duct 20, designated by the term of "casing", and formed for example by an assembly of tubes applied against the formations of the subsoil 14. Advantageously, the well 12 includes at least one inner tubular duct 22 with a smaller diameter mounted in the outer tubular duct 20. In certain cases, the well 12 is without any duct 20, 22.
The inner tubular duct 22 is generally designated as "production tubing". It is advantageously formed with a metal assembly of metal tubes. It is wedged inside the outer tubular duct 20 for example by linings 24.
The well 12 includes a well head 26 at the surface which selectively closes the outer tubular duct 20 and said or each inner tubular duct 22. The well head 26 includes a plurality of selective access valves inside the outer tubular duct 20 and inside the inner tubular duct 22.
The intervention installation 10 includes an intervention device comprising an lower assembly 30 comprising a cementing apparatus intended to be lowered into the well 12 through the inner tubular duct 22, and a conveying cable 32 for deploying the lower assembly 30 in the well 12. The lower assembly will be described in more details with reference to figure 2.
The intervention installation 10 further includes a sealing and alignment assembly 34 of the cable 32, mounted on the well head 26, an assembly 36 for deploying the cable 32, positioned in the vicinity of the well head 26, and a surface control unit 38, which will be described in more details in reference to Figure 3.
The sealing and alignment assembly 34 comprises an airlock 42 mounted on the well head 26, a stuffing box 44 for achieving the seal around the cable 32 and return pulleys 46 respectively attached on the stuffing box 44 and on the well head 26 in order to send back the cable 32 towards the deployment assembly 36.
The airlock 42 is intended to allow introduction of the lower assembly 30 into the well 12.
The stuffing box 44 is capable of achieving a seal around the smooth outer surface of the cable 32, for example via annular linings applied around this surface or/and by injecting a fluid between the outer surface and the wall of the stuffing box 44.
In a so-called "open well" or "open hole" alternative, in which there is no casing 20, the assembly 34 is exclusively an assembly for aligning the cable, without any sealing device.
The deployment assembly 36 includes a winch 37A provided with a winder 37B. The winch 37A and its winder 37B are laid on the ground or are optionally loaded onboard a vehicle (not shown). The winch 37A is capable of winding or unwinding a given length of cable 32 for controlling the displacement of the lower assembly 30 in the well 12 when moving up or down respectively. An upper end 41A of the cable is attached onto the winder 37B.
The surface control unit is connected to at least a measuring device 50 for measuring a value of a parameter. The system may also not comprise any measuring device at surface. Other detection devices may also be included in the surface unit.
In the embodiment of figure 1, the measuring device 50 is for measuring the length of the slickline cable that has been unwound from the winch 37A and deployed in the well and therefore the approximate depth of the lower assembly. This measuring device is a sensor that is known in the art, such as an optical, mechanical or electrical sensor. It may for instance count the number of turns that have been performed by the winch 37A for deploying the cable into the well.
As illustrated by Fig. 2, the cable 32 is a cylindrical solid cable having a smooth outer surface 40.
The cable 32 extends between an upper end 41A, attached on the deployment assembly 36 at the surface, and a lower end 41B, intended to be introduced into the well 12. The lower assembly 30 is suspended from the lower end 41B of the cable 32.
The length of the cable 32, taken between the ends 41A, 41B is greater than 1,000 m and is notably greater than 1,000 m and comprised between 1,000 m and 10,000 m.
The cable 32 has an outer diameter of less than 8 mm, advantageously less than 6 mm.
The cable 32 includes a central metal core, and an insulating outer sheath applied around the central core.
The central core is formed by a single strand of solid metal cable, designated by the term "piano wire" and sometimes by the term of "slickline cable".
The metal material forming the core is for example electroplated or stainless steel. This steel for example comprises the following components in mass percentages:

Carbon: between 0.010% and 0.100%, advantageously equal to 0.050%;
Chromium: between 10% and 30%, advantageously equal to 15%;
Manganese: between 0.5% and 3%, advantageously equal to 1.50%;
Molybdenum: between 1.50% and 4%, advantageously equal to 2%;
Nickel: between 5% and 20%, advantageously equal to 10%;
Phosphorus: less than 0.1 %, advantageously less than 0.050%;
Silicon: less than 1% advantageously less than 0.8%;
Sulphur: less than 0.05% advantageously less than 0.03%;
Nitrogen less than 1%, advantageously less than 0.5%.

This steel is for example of the 5R60 type.
The core is solid and homogeneous over the whole of its thickness. It has a smooth outer surface.
The diameter of the core is typically comprised between 1 mm and 5 mm, advantageously between 2 mm and 4 mm, and is for example equal to 3.17 mm, i.e. 0.125 inches.
The core has a breaking strength of more than 300 daN, and notably comprised between 300 daN and 3,000 daN, advantageously between 600 daN and 2,000 daN.
The core further has a relatively high electrical linear resistance of more than 30 mohms/m, and for example comprised between 50 mohms/m and 150 mohms/m.
The core has sufficient flexibility so as to be wound without any substantial plastic deformation on a drum with a diameter of less than 0.8 m.
The outer sheath forms an annular sleeve applied on the core, over the whole periphery of the core, on substantially the whole length of the cable 32, for example on a length of more than 90% of the length of the cable 32, taken between its ends 41 A, 41B.
The outer sheath thus has a cylindrical inner surface applied against the central core and a smooth outer surface delimiting the smooth outer surface of the cable 32.
The thickness of the sheath is advantageously comprised between 0.2 mm and 2 mm.
The outer sheath includes a polymer matrix.
The matrix is made on the basis of a polymer such as a fluoropolymer of the fluorinated ethylene propylene type (FEP), perfluoroalkoxyalkane, polytetrafluoroethylene (PTFE), perfluoromethylvinylether, or on the basis of a polyketone such as polyetheretherketone (PEEK) or polyetherketone (PEK), or on the basis of epoxy, optionally taken as a mixture with a fluoropolymer, or further based on polyphenylene sulfite polymer (PPS), or mixtures thereof.
Advantageously, the polymer matrix is made in polyetheretherketone (PEEK).
The outer sheath optionally comprises mechanical reinforcement fibres embedded in the polymer matrix.
Such a slickline cable 32 is able to transmit electrical signals from the lower assembly 30 and the surface unit.
The surface unit 38 includes a surface transceiver 102 for communication with the lower assembly 30 through the cable, a detection module 104, a control interface 106 and a triggering panel 108.The control unit 38 further includes a module 114 for controlling the winch 37A and winder 37B.
The surface transceiver 102 is electrically connected downstream to the core of the cable 32 via a first electrical surface path 110. It is electrically connected downstream to the well head 26 and to the ducts 20, 22 via a second electrical surface path 112. The transceiver comprises a surface transmitter for transmitting data downhole and a surface receiver for receiving data coming from downhole. It is therefore capable of transmitting and receiving various electrical signals on a current loop defined by the first electrical path 110, the cable 32, the lower assembly 30, the ducts 20, 22, the well head 26, and the second electrical surface path 112. Path 110, cable 32, ducts 20, 22, well head 26 are part of a communication module for transmitting data uphole to downhole or downhole to uphole. This communication module provides real-time communication between the surface and the lower assembly.
The control unit further includes a detection module 104 which is connected to the measuring device 50. This detection module is also connected to the surface transceiver 102. It receives data from the measuring device 50 and compares a value measured by the measuring device 50 with a threshold value. It can also acknowledge the presence of an identification device at a predetermined location by optical or electrical detection (for instance, when the identification device is a key, able to activate a switch), or check a password of an user to ensure he is authorized to use the surface control unit.
The control unit further includes an interface 106 also connected to the surface transceiver 102. The interface 106 advantageously comprises a keyboard, a display screen and a central processing unit such as for example a computer. The triggering panel 108 includes a mechanical button or any other mean for triggering the operation of the lower assembly and in particular of the cementing apparatus. It may also comprise a power-on indicator lamp. The triggering panel is also connected to the surface transceiver (in this embodiment, via the user interface). It can also be noted that the detection device, triggering panel 108 and user interface 106 can be one sole device.
The transmitter of the surface transceiver 102 may operate in function of the data received from the detection device 104 and triggering panel 108 as will be explained below.
The control unit itself can be a computer device comprising a storage medium storing computer programs comprising machine-readable instructions and a processor for executing these programs, enabling to operate detection and surface transceiver 102.
The lower assembly 30 will now be described in more details in particular in view of FIG.1 and 2.
The lower assembly 30 also comprises a transceiver 120, called downhole transceiver for communicating with the surface transceiver 102 via first and second electrical paths 110 & 112. Downhole receiver also comprises transmitter and receiver. This transceiver is connected to a cementing apparatus 122 that will be described in more details in FIG. 2 and to an insulation system 121 for insulating a cementing zone from the rest of the wellbore, for instance with the help of inflatable packers situated at both ends of the cementing apparatus.
The cementing apparatus 122 comprises a first tank 124 containing gas such as nitrogen, a second tank 126 containing a slurry of at least cement and water which may optionally contain other additives, such as accelerators, a mixing device 128 and a triggering device 130.
The mixing device is an eductor and comprises first and second inlets 131, 132 respectively connected to an outlet 134, 136 of the first and the second tank. It also comprises an outlet 138 for letting out the mixed concrete. The outlet 138 opens on the outside wall of the lower assembly 30 so that the concrete may be directly provided in the wellbore.
The line connecting the outlet 134 of the first tank 124 and the inlet 131 of the mixing device is provided with a valve 140 movable between a closed position in which the fluid contained in the tank is blocked there by the valve, and an open position, in which the fluid contained in the tank may circulate to the mixing device 138. Such a valve 142, 144 is also provided on the line connecting the second tank 126 and the mixing device 138 and on a third line connecting the second tank to the outside of the lower assembly.
The mixing device 128 in the embodiment is an eductor. It comprises a flow restrictor and enlargement section 146 on the circulation path of the gas in the eductor. It also comprises a one-way valve 148 at the outlet 138 of the mixing device 128 that allows the fluid out of the mixing device for instance if the pressure inside of the mixing device is greater than a predetermined pressure.
The triggering device 130 is electrically connected to the valves 142-146 and is able to command them in order that they move from a position to the other. Triggering is enabled from surface with telemetry via cable 32 and transceiver 120 which is connected to triggering device.
Alternatively, triggering device may be enabled by any signal received from any remote emitter situated in the wellbore or at the surface. The downhole transceiver may for instance communicate with other transceiver at surface or in the wellbore via electromagnetic waves.
We will now explain in view of FIG.3 the method 200 of cementing a wellbore according to an embodiment of the disclosure.
First, at surface, the lower assembly 30 is attached to the slickline cable 32 so that the transceiver 120 is connected to the cable. The tanks 124, 126 of the cementing apparatus are then full respectively of gas and of slurry and the valves 142-146 are closed, as shown on FIG.2A. The lower assembly is then lowered into the wellbore (box 202).
The measuring device 50 measures the length of the cable 32 that has been unwounded into the wellbore. In function of where in the well the cementing job should occur, the detection device 104 is configured so as to detect when the length reaches a predetermined length (box 204).
If the predetermined depth is not yet reach, the measuring device continues monitoring. If it is reached, the detection device 104 commands the control module 114 of the winch to stop unwinding the cable (box 206) and the transceiver 102 of the surface control unit 102 to send at least a predetermined signal downhole via the cable 32 (box 207).
The predetermined signal is received by the downhole transceiver unit 120 which sends an electrical triggering signal to the insulation system 121, so that it triggers the insulation of the cementing zone in the wellbore (box 209) by inflating the packers and then, optionally when it is detected that the cementing zone is sealed, to the triggering device 130 (box 210). When receiving the signal, the triggering device 130 commands the valves 142-146 to move from a closed position to an open position (box 212). The cementing apparatus may not include any battery, the power of the signal transmitted from the surface via the slickline cable being sufficient to energize the valves. When the valves are in an open position, it allows the gas which is highly pressurized to release in the eductor (box 214), creating a vaccuum effect to move the cement slurry towards the eductor when the gas reaches the enlargement section 148 (box 216). The combination of gas and slurry flows mix in the eductor chamber (box 218) resulting in a foam concrete flow. When the foam concrete has been mixed and a predetermined pressure is set into the chamber, the concrete is released into the wellbore so that it is released at a predetermined position chosen from surface by the operator (box 220). The state of the cementing apparatus at box 220 is shown on FIG.2B.
After a predetermined time for which it is determined that the concrete has set, the insulation system is deactivated, for instance the packers are deflated (box 222). This deactivation of the insulation system may be triggered by an internal clock or by a signal sent from the surface, for instance in function of data received from the lower assembly that may enable to determine if the concrete has set or not thanks to any measurement or detection device. The lower assembly is then moved back to the surface (box 224).
The apparatus according to the disclosure may be easily lowered into the wellbore and do not necessitate a complicated or expensive installation for producing the concrete. Moreover, as it may be activated from the surface and/or on reception of a signal coming from an external element, the concrete may be released at a precise location in the wellbore.
This method may be used for instance for plugging the wellbore before abandoning it, and/or repairing the cemented part of the wellbore and/or closing perforations formed in the cemented part of the wellbore and the casing.
In view of the entirety of the present disclosure, including the figures, a person skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same uses and/or achieving the same aspects introduced herein. A person skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure. For example, although the preceding description has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein; rather, it extends to functionally equivalent structures, methods, and uses, such as are within the scope of the appended claims.
It will be for instance appreciated that the signal may come from the surface but not via an electric signal on the cable. For instance, it may be transmitted mechanically from the surface, by pulling on the cable according to a predetermined sequence or via electromagnetic transceiver situated at the surface and/or in the wellbore (as repeater or as marker of a predetermined location).
Further, the cement slurry may include any additives, accelerator, strengthener, etc. that may appear necessary in view of the required cementing job. These additives may also be stored in another additional tank.
The concrete may not be a foam concrete. It may necessitate to lower several times the assembly into the wellbore for performing the job as the mixed concrete will not expand as the foam concrete but it may work as well. The first tank may then comprise a cement slurry and the second may comprise a liquid such as water.
Further, the apparatus may not be designed as indicated in the disclosure. It may not comprise an eductor for mixing the concrete but any other appropriate device instead. The apparatus may not include any valve.The triggering device may also trigger other parts of the apparatus than the valves. It may for instance control the pistons of pumps in which the different components intended to be mixed are stored. The apparatus may also include a battery for powering the triggering device or any other device.
The tank may also be constituted differently relative to what has been disclosed. A tank may for instance include two compartments, one being connected to an input of the mixing device comprising a component to be mixed in the mixing device and another being a closed compartment comprising a gas. The pressurized gas may push the component stored in the open compartment when the triggering device opens the valve situated on the line between the output of this compartment and the input of the mixing device. The apparatus may also include more than two tanks.
Of course, other variants may also be part of the disclosure as defined by the claims.

Claims

A cementing apparatus for mixing concrete in a wellbore, the cementing apparatus being intending to be lowered into a wellbore and comprising :
- a first tank, intended to receive at least a first component of a concrete,

- a second tank, intended to receive at least a second component of a concrete,

- a mixing device comprising at least two inlets respectively connected to the first and second tanks for mixing the first and second components, and an outlet,

- a triggering device for triggering at least the entry of one of the first and second component into the mixing device, upon reception of a signal coming from the surface, the wellbore or the formation.
The cementing apparatus of claim 1, wherein the mixing device is an eductor.
The cementing apparatus of the preceding claim, wherein a valve is positioned between the outlet of at least one of the tanks and the inlet of the mixing device.
The cementing apparatus of the preceding claim, wherein the triggering device triggers the opening of at least one of the valves.
The cementing apparatus of any of the preceding claims, wherein at least one of the tank comprises a piston, the apparatus comprising a motor for moving the piston into the tank, wherein the triggering device triggers the operation of the motor.
The cementing apparatus of any of the preceding claims, wherein the first component is a cement slurry.
The cementing apparatus of any of the preceding claims, wherein the second component is a pressurized gas, such as nitrogen.
The cementing apparatus of any of claims 1 to 6, wherein the second component is a liquid, such as water.
The cementing apparatus of any of the preceding claims, wherein the triggering device is connected to a receiver configured to receive electric or electromagnetic signals coming from the surface, the wellbore or the formation.
A cementing system, comprising :
- A lower assembly comprising the cementing apparatus of any of the preceding claims,

- A slickline cable for conveying the lower assembly into the wellbore.
The cementing system according to claim 10, comprising a communication module including the slickline cable and configured to transmit electrical signals between the surface and the lower assembly, and an emitter positioned at surface for emitting the predetermined signal.
The cementing system according to claim 11, wherein the emitter is configured for sending the predetermined signal upon completion of a monitored criterion.
The cementing system according to claim 12, wherein the system comprises a measurement unit of at least a parameter at the surface, such as a length of the slickline cable deployed into the wellbore, the criterion being completed if the value of the parameter is in a predetermined range of values.
A cementing method comprising :
- lowering a cementing apparatus according to any preceding claims into a wellbore,

- receiving a predetermined signal by the triggering device,

- triggering at least an element of the cementing apparatus so that the first and second components enter the mixing device,

- mixing the concrete from the first and second component,

- depositing the mixed concrete in the wellbore.
The cementing method according to claim 14, wherein depositing the mixed concrete comprises forming a plug in the wellbore or closing perforations of the casing or repairing the cement of the wellbore.
The cementing method according to claim 14 or 15, comprising isolating a cementing zone from the rest of the wellbore after receiving the predetermined signal.
The cementing method according to claims 14 to 16, comprising detecting if the apparatus is at a predetermined position, and sending the predetermined signal when the apparatus is at the predetermined position.
The cementing method according to claim 17, wherein detecting if the apparatus is at a predetermined position comprises measuring the length of a cable conveying the lower assembly.
The cementing method according to any of the claims 14 to 18, comprising sending a predetermined signal from the surface via a communication module comprising the cable conveying the lower assembly into the wellbore.