FR2976966A1 - Drill string element for use with well head device, has antenna monitor for evaluating parameter for sub-assembly to select antennae set as parameters derived from sub-assembly and command actuator to connect antennae to electronics - Google Patents

Abstract

The element has a wave type communication device arranged in a body (600) and a set of antennae (627) distributed at a periphery of the body about the axis of symmetry for operating the antennae in transmission and reception. An operating electronics organizes the data transfer in transmission and in reception. An antenna monitor evaluates a reception quality parameter for a sub-assembly of the antennae to select the antennae set as a flinction of reception quality parameters derived from the sub-assembly and to command an actuator to connect the antennae to the electronics. Independent claims are also included for the following: (1) a well head device (2) a method for providing communication by a drill string element (3) a method for drilling, exploration and/or operation of a hydrocarbon well.

Description

The invention relates to deep or deep drilling, in particular oil drilling. DESCRIPTION OF THE PREFERRED EMBODIMENTS As oil drilling progresses, it is necessary from time to time to add one or more tubes at the head of the wellbore. This is why such a well has on the surface a vertical carrier structure that is called "derrick". The derrick and the equipment therein, including the rotary drive system, will be referred to herein as a "wellhead apparatus". As will be discussed in more detail below, a wellhead apparatus is a narrow and very congested place. The derrick carries a mechanical system that allows to hold the column of drill pipes ("drill string"), as well as up and down. When lifting the column of tubes, the vertical upward excursion is ten meters or more. It is the same for the downward vertical excursion during drilling. The wellhead apparatus further includes driving the spinning column of tubes for drilling, as well as the system for unscrewing and screwing one or more tubes (or other equipment) onto the column. already formed tubes. In addition, there is the system for injecting and recovering drilling muds, which serve in particular to operate the drill bit. Finally, different types of security systems are needed. Attempts are currently being made to make the column of tubes communicating, so as to be able to exchange information between, on the one hand, the top of the well, and on the other hand the bottom of the well, or intermediate equipment inserted in the column. of tubes. For this, within the tube column, each tube is equipped with communication couplers at its ends, and an electrical connection between these couplers. At the top of the well, it is necessary to pass the information between the column of tubes, which rotates and moves vertically, and a fixed surface electronic equipment. The connection between the column of tubes and this electronic surface equipment is called here "surface interface". The choice of this connection by the surface interface is critical. Indeed, if this link comes to an end, the communication equipment provided in the column of tubes 30 itself becomes useless, and we lose all the information and commands on which we counted.

We can imagine many solutions. Of these, few are really applicable in practice, because of the many constraints that must be met, especially because of the crowded environment of the wellhead device. For example, US 2010/0214121 discloses a drilling column provided with a communication device comprising a single transmitter capable of operating a wireless transmission with one or more fixed "coordinators". These coordinators are in fact receiving antennas located at the wellhead. The proposed transmission complies with the IEEE 802.15.4 standard, which allows data to be transferred at a relatively low rate. The communication device in question uses control or beacon signals from the coordinator (s) to determine the best coordinator available and / or, for a particular coordinator, the best time to transmit data to him or her. The data transmission is limited to a part of the rotational path of the column, typically an arc of 120 °, or at certain time periods. This is to minimize the energy consumed for data transmission. It is then necessary to calibrate the transmitter on the coordinators to determine time periods suitable for data transfer: once a valid coordinator has been detected, the rotation speed of the column is used to determine a succession of time periods of time. transmission, which correspond to the successive passes of the transmitter near the coordinator in question. The known device of US 2010/0214121 suffers from certain disadvantages. As we have seen, it is necessary to know the rotational speed of the column, which is likely to vary over time, for example according to the evolution of drilling difficulties. Typically, additional sensors must be embedded in the column, which poses the problem of their integration and their power supply. In addition, for high rotational speeds, there is little time to carry out a data transfer. It also appears that the device in question offers only a relatively small transfer rate, which may be insufficient, particularly because of recent improvements in the field of feedback from the bottom of the well.

Finally, it is difficult to multiply the number of coordinators, that is to say receiving antennas, because, as we saw above, the environment offered by the wellhead device is already very cluttered by elements essential to drilling operations.

US 2010/0224409 A1 discloses a wear insert, or "saver sub" in English, which is used to connect the drill string column to the drive system. This wear insert is equipped with antennas that allow wireless data transmission with a surface antenna, made in the form of a satellite dish. According to US 2010/0224409 A1, the transmission / reception of the data could be done approximately in all directions, in particular 360 ° around the insert, which would establish a communication even when the insert is moved. in rotation or moved in any way. The operation of these antennas is not explained in more detail. It seems that the idea is to radiate as widely as possible all antennas around the wear insert, in all directions, so that the satellite dish can almost always capture the data transmitted by the insert in question. The system of US 2010/0224409 A1 does not solve certain problems that arise in practice in the art, such as the energy consumption of embedded electronic elements or the congestion of the wellbore environment, to name but a few. some.

The present invention improves the situation. It relates to a drill string element of the type comprising an axisymmetric general-looking body and a wave communication device embedded in said body. This element is remarkable in that the communication device comprises a set of antennas comprising a plurality of antennas distributed at the periphery of said body, around the axis of symmetry thereof, and capable of operating in transmission and transmission. reception, work electronics capable of organizing data transfers, transmitting and receiving, an actuator capable of selectively connecting the antennas of said game to the work electronics, and an antenna monitor arranged to regularly evaluate a magnitude of reception quality for at least a subset of the set of antennas, repetitively selecting one or more antennas of said set according to reception quality variables from said subset and controlling the actuator to connect the antenna or antennas as well selected at work electronics.

The proposed element allows communications between the drill string and one or more fixed surface devices that exhibit excellent throughput and low power consumption. Optional features of the invention, complementary, additional, or substitution, are set out below: The selected antenna or antennas comprise one or more antennas among said subset and / or one or more antennas adjacent antennas of said sub -together. The antenna monitor is further arranged to periodically evaluate a switching criterion and to control the actuator whenever the switching criterion is verified. The switching criterion comprises a comparison between a time elapsed since the last activation and a predetermined duration. The predetermined duration is calculated from a rotational speed value of said body, taking into account the distribution of the antennas around the axis of symmetry of the body. - The rotational speed value is determined from the time evolution of the reception quality quantity of at least one of the activated antennas. The switching criterion comprises a comparison of substantially instantaneous values of reception quality variables relating to the activated antennas on the one hand and to the other antennas of said subassembly on the other hand. The work electronics is able to switch repeatedly between a receive mode and a transmission mode. The working electronics is arranged to operate in transmission mode for a period of time of a determined duration and to switch to transmit mode in the absence of modification of the antennas connected to it during said time period. The set of antennas comprises a plurality of surface antennas regularly distributed around the axis of symmetry of said body. 30 - The body houses a safety valve.

The invention also relates to a device for a wellbore head, comprising at least one drilling column element as proposed above, and a wellbore head comprising at least one such device integral with a drive. in rotation with respect to a derrick and one or more fixed antennas with respect to this derrick. The body of the element may then have a high end thread, a low end thread, an end coupler, arranged at its lower end, intended to cooperate with a homologous end coupler of another element. screwed on the bottom end thread, and an electrical connection arranged between the end coupler and the work electronics. The device may further comprise a valve arranged in an intermediate part of the body, between the upper end thread and the lower end thread. The invention also relates to a method of communication using a drill string element comprising a generally axisymmetrical body and a set of antennas, comprising a plurality of antennas distributed at the periphery of said body, around its axis of symmetry, and capable of operating in transmission and reception, comprising a step of evaluating at least one reception quality variable for at least one subset of the set of antennas, a step of selecting one or more antennas of said set as a function of the reception quality variable (s) from said subset, and a step of organizing a transmission of data, in transmission and / or reception, by the intermediate of the selected antenna (s). The evaluation step may be performed regularly, and / or the selection step repeated. The invention also relates to a method of drilling, exploring and / or operating a hydrocarbon well comprising one or more communications implemented in accordance with the method mentioned above. Other features and advantages of the invention will be apparent from the following detailed description, and the accompanying drawings, in which: FIG. 1 is a simplified schematic elevational diagram of a wellhead apparatus at 30 traditional training by rotating table; Figure 2 is a schematic diagram of the screwed components used at the top of the column of tubes, in the case of the wellhead apparatus of Figure 1; FIG. 3A represents, in isometric perspective, a modern drive, by motor at the top; Figure 3B shows the upper portion of the drive of Figure 3A; Figure 3C shows the lower portion of the drive of Figure 3A; FIG. 4 shows the screwed components used at the top of the column in the case of the drive of FIG. 3; Figs. 5A and 5B are two detailed partial views of a 10 well head apparatus equipped with the drive of Fig. 3; FIGS. 6A and 6B respectively represent two alternative embodiments of a drilling column element, seen in partially truncated isometric perspective; Figure 7A is a schematic diagram of the elements of Figures 6A and 6B; FIG. 7B represents an alternative embodiment in a view similar to that of FIG. 7A; FIG. 8 represents a schematic diagram of an on-board electronics in the elements of FIGS. 6A and 6B; FIG. 9 represents a block diagram of a surface electronics used in combination of the elements of FIGS. 6A and 6B; FIG. 10 illustrates an exemplary embodiment of a portion of the electronics of FIG. 8; Figures 11 to 13 are flow charts illustrating the operation of the on-board electronics of Figure 10; Figure 14A shows a tubular insert in longitudinal section; Figure 14B shows an alternative embodiment of the insert in a view similar to Figure 14A. The attached drawings are largely of a certain character. Accordingly, they can not only serve to better understand the detailed description below, but also contribute to the definition of the invention, if any.

The established oil drilling terminology is in English. And many of these English words have no usual equivalent in French. Therefore, in the present description, and for the sake of clarity, a technical expression in French is very frequently accompanied by the corresponding consecrated expression in English.

In FIG. 1, the wellhead apparatus as a whole is designated by reference numeral 1. It comprises the well-known slender pyramid, or derrick 10, at the top of which is a return pulley 11 housed in a cap 12. The return pulley 11 supports by cable a terminal pulley, or muffle 14 ("traveling block"). This set forms a hoist ("hoist") which itself supports a pivot 20, said "swivel", which in turn supports a set that will be described in detail later, and which comprises a drive rod 21 , called "kelly drive" or, more briefly, "kelly". This drive rod 21 cooperates with a turntable 23 ("rotary table"), whose rotation drive is schematized here by a peripheral ring 25, a roller is mechanically driven by chain or belt by an intermediate pulley 24, of which the shaft is itself driven from the output pulley of a motor 2. The turntable 23 is located at a floor 22 of the derrick 10. At the bottom, in the example, the column of tubes drilling begins at ground level by a casing head 29 integral with the casing 30 or "casing" of the well. Inside this casing 30 passes the column, or chain, of tubes 26, called "drill string", which ends with a drill bit 27 called "drill bit", consisting for example of rotating abrasive wheels. The return pulley 11 is driven by a winch 16, driven by a motor not shown. The reference 15 designates the traction cable which supports the column of tubes, via the muffle 14 and the idler pulley 11.

The bit 27 needs energy to operate, and this energy is transmitted to it by mud pressure and / or various rotation mechanisms located on the surface or along the drill string, for example one or more engines. Sludge is extracted from a tank 40, by a suction pipe 41 which goes to a pump 42 driven by a motor not shown. This sludge is used to lubricate the bit 27, cooling, to remount the chips from the bottom of the well, to balance it in pressure, to clean and operate some of the equipment of the column of tubes.

At the outlet of the pump 42, a pipe goes up along a wall of the derrick 10, to end in a gooseneck 43 from which the pipe goes down again to go up on another gooseneck 45, and to attach to the top of the pivot 20 so that the sludge can enter the column, pass through the drive rod 21, and this up to the level of the casing head 29. The sludge then descends through the column of tubes 26 to operate the bit 27. It goes up between the column 26 and the casing 30, up to the casing head 29, where it is taken up through two safety members 33, of the valve type, called "blow out preventers". "one, said" blind ram ", is able to crush the casing 30 annularly to isolate it, while the other, said" shear ram ", is able to cut and close the assembly formed of the casing 30 and the tube column 26. The mud then rises to a sort of expansion vessel 31, called "bell nipple", from the it passes through a return line 47 before reaching the tank 40, through a member 49 which filters the sludge. The gases are filtered and the chips removed.

In the left part, the floor 22 is extended in 50 to serve as a support for a reserve of tubes 51 ("stand"), held in the upper part by a rack 52 called "finger board". It is understood from the foregoing that between the muffle 14 and the column of tubes 26, at the head of this column, are arranged elements which drive this column 26 in rotation. This training corresponds to the elements included in the dashed frame, and here comprises the pivot 20, the driving rod 21, the turntable 23 and the peripheral ring 25. The movable elements, from the central column of the derrick, to muffle 14, including the pivot 20 and the drive rod 21, undergo a vertical excursion of ten meters or more.

The derrick houses other elements, not shown in Figure 1: - a support system of the column of tubes 26, when disconnected from the hoist, - handling equipment tubes between the reserve 51 and the column central, - a system that allows unscrewing or screwing on the column of tubes 26, to add or remove a length of tube, - safety valves, inserted in particular at the top of the column of tubes, - a hydraulic clamp ("hydraulic clamp") to hold the tubes while they are being screwed onto the drive. Reference is now made to FIG. 2. In the central portion, the profiled drive rod, known as "kelly", is shown. This is a long rod polygonal cross section, in principle square or hexagonal, noted KD I in Figure 2. This rod is secured to end threaded ends, denoted KD_U at the top and KD_L at the bottom. The assembly formed by the rod KD_I, and its tips KD_U and KD_L is globally noted KD (for "kelly drive"). The top thread of the upper end piece KD_U comes into contact with a top wear insert, noted USavSub, surmounted by a high security valve called "upper kelly valve", denoted UKV, and which is in principle manually operated. At the bottom of the profiled rod KDson lower end piece KD_L engages on a so-called "low kelly valve" called LKV, in principle pneumatically actuated, followed by a low wear insert LSavSub, to which is fixed the column of tubes 26.

The LSavSub low wear insert can also be used as a thread adapter. Indeed, its low thread must be compatible with the thread specified for the column of tubes 26. On the other hand, its high threading may be different. In particular, the manual valve can serve as a security, in case the pneumatic valve does not close the well completely.

It has been seen that, in the wellheads according to FIGS. 1 and 2, the drive is done by a turntable 23, whose rotational movement is transmitted to the profiled rod KD_I. A removable sleeve ("kelly bushing"), not shown, defines a shape profile corresponding to the square or hexagonal profile of the rod KD_I. The detachable bushing is inserted between the turntable 23 and said profiled zone KD_I. Thus, the turntable 23 drives the profiled rod KD_I in rotation, while leaving it free in vertical translation, to accompany the descent of the column of tubes 26 as drilling progresses. Tubes are added as this progresses. We are now at a moment when we have just added one or more tubes to the column. The profiled rod KD_I is then entirely out of the well, and the turntable 23 is engaged on the bottom of its profiled zone. This is the "high position" of the column of tubes 26. The rod KD_I slid down as the drilling progresses, until it is the top of its profiled zone which comes into contact with the turning table. This is the "low position" of the column of tubes 26. It is then time to add one or more tubes. For this, we stop the rotation (drill), and we remove the removable sleeve; the column of tubes 26 is raised to a height substantially equal to the length of the profiled rod KD_I; the column of tubes 26 is blocked under the rod KD_I; and the rod KD_I of the column is unscrewed. A new tube is screwed at the top of the column of tubes 26. The column of tubes 26 is lowered downwards from the aforementioned height, so that the bit 27 returns to the bottom of the well. We screw the rod KD_I at the top of the column. It remounts the removable sleeve which ensures the rotational coupling of the rod KD_I to the turntable 23. The bore can then resume. Things are essentially the same, with vertical displacements in the opposite direction, when it is necessary to extract the column of tubes 26, totally or partially. Known techniques allow the laying of casing tubes, or "casing", sequentially after the drilling of a section of wells (a depth). As drilling progresses, there will be numerous unscrewing / screwing operations on the same thread of the same component. And these screwing / unscrewing are under a strong constraint, due to the weight of the column of tubes, which may ultimately include one or more hundreds of tubes, resulting in rapid wear of this thread. That is why it is usual to use one or more wear inserts known as "saver sub", in places subject to unscrewing / revivals repetitive. In the case of Figures 1 and 2, there are two wear inserts, respectively placed at the top (USavSub) and bottom (LSavSub) of the profiled rod KD_I, or "kelly". These upper and lower inserts relative to the profiled rod KD_I are respectively designated "upper kelly saver sub" and "lower kelly saver sub" in the art. Reference is now made to FIGS. 3A, 3B and 3C, which illustrate a more modern embodiment of the wellhead apparatus. In recent wells, the wellhead apparatus is equipped with a top drive system, noted TD, shown as a whole in Figure 3A. The drive is mounted at the top of the column of tubes, directly supported by the muffle 14 through a loop SB ("system lease") attached thereto.

In its upper part, shown alone in FIG. 3B, the drive at the top TD comprises an electric motor DM ("drilling motor") which rotates a driving rod DS ("drive stem") via a TR transmission ("transmission"). This upper part also comprises a pair of hydraulic brakes HB ("hydraulic brakes"), as well as a cooling system comprising a pair of cooling ducts ("cooling system air duce") connected to the engine DM and in which circulates from the engine. The DS stem is hollow, for the same purpose as before, mud is injected into the DS stem by means of a GS gooseneck (air-cooled fan). "gooseneck"), through a cap BO ("cap"), and a cleaning assembly WP ("wash pipe packing assembly"). In its lower part, visible singly in Figure 3C, 1 TD includes a powered PEP (powered locator positioner) positioner that can rotate 360 degrees around the axis of the DS rod A backup clamp (BUC) is connected to the positioner PEP via a torque limiting frame TAF, called "torque arrester frame" Elevators E ("elevators") equipped with a hydraulic clamp HC (hydraulic clamp) are mounted at the end of linkage EL ("elevator links") whose opposite end is attached to the positioner PEP by RLA ("rotary link adapters") rotary adapters. The RLA adapters allow pivoting of the arms EL relative to the axis of the drive rod DS under the action of a link actuated assembly ("link tilt assembly") attached to the positioner PEP. The rescue clip BUC comprises adjustable stabilizing guides SG ("adjustable stabling guide"), not shown. In FIG. 3C, an upper UBOP ("upper blow out preventer") and lower LBOP (lower blow out preventer) safety assembly are also interposed between the rod DS and a wear insert (FIG. "saver sub") not visible. The BUC relief clip, placed above the hydraulic clamp HC, engages almost all of the wear insert. The TD drive is guided by a vertical rail VR (Figure 3A), shifted laterally.

The TD training goes down as drilling progresses, until it is close to the floor of the derrick 10. The addition of a length of tubes is a bit simpler than before. The tube column is blocked by a strong tightening, and it is unscrewed from the DS rod, more precisely from a wear insert, called "top drive saver sub", fixed under the lower safety assembly LBOP. In this case, there is only one wear component. Move the engine up the derrick 10. Add one or more tubes. And the column of tubes is revised on the wear component, remaining attached to the drive TD.

The UBOP and LBOP assemblies comprise respectively a top UKV (upper kelly valve) and a lower kelly valve (LKV), placed one above the other, between the stem. DS and the SavSub wear insert. Traditionally, they retain their names "upper kelly valve" and "lower kelly valve", although there is more profiled rod called "kelly" in this embodiment.

Figure 4 shows the arrangement of the column head, in the case of the wellhead apparatus of Figures 3A-3C. The DM motor drives the DS rod which is threaded and engages on the UKV top safety valve. In this embodiment, it is immediately followed by the LKV lower safety valve, then the SavSub wear insert, which is unique here.

As already indicated, it is now sought to make the column of tubes communicating, so as to be able to exchange information between on the one hand the top of the well, and on the other hand the bottom of the well, or intermediate equipment inserted in the column of tubes. For this, within the tube column, each tube is equipped with communication couplers (in short "couplers") at its ends, and an electrical connection between these couplers. Known solutions for this purpose are described, in particular in the document "US DOE report" referenced "report # 41229R14". This document is available in particular at the following internet address: http: //www.netl.doe. gov / technologies / oilgas / publications / epreports / dcs / final% 20report% 20fg123104.pdf These solutions suffer from various disadvantages. One of these solutions, known as "SwivelLink", incorporates a rotary joint type transmission electronics in an insert, or "sub", specialized, which will naturally be long enough to house the transmission electronics. . Indeed, it is necessary to preserve the internal passage section, for drilling muds, in particular.

The transmission electronics takes place in a housing arranged in the tubular peripheral wall of the insert, hence the elongation. The use of this first solution involves a complete rethinking of the architecture of the wellhead device, because of said elongation. This greatly limits the scope of this solution. In addition, this involves reviewing all the standards applicable to the elements of the wellhead, which has serious consequences in terms of cost. If on the other hand we wanted to integrate this first solution in the head drive "top drive system" of an already existing well, to the current standards, it would then be necessary to sacrifice one of the elements at the head of the column of tubes: to remove the one of the two UKV and LKV safety valves, or replace the SavSub wear insert. The document report # 41229R14 also describes a second solution, known as "Data Swivel", where the wear insert "saver sub" is provided with a rotating electrical joint, a fixed part of which relative to the derrick 10 is connected to a cable long enough to accommodate the vertical excursion of the wear component during drilling.

But as shown in Figure 4, the BUC relief clip engages the wear insert over most of its length. There is therefore a significant risk of damage to the rotating electrical seal and / or the cable carried by it when the wear insert is tightened by the hydraulic backup clamp-lock. This deterioration is unacceptable because the entire communication system of the column of tubes is then cut. For the same reasons as above, the elongation of the wear insert is not conceivable, especially since the BUC backup clip is at a fixed distance from the rest of the TD head drive: the elongation of the wear insert towards the top of the column of tubes would imply to provide for the suppression or the shortening of the elements that are usually there when they are safety devices; this would also lead to making specific elements so, finally, to change virtually all of the column head, from the wear insert to the drive rod; the extension of the wear insert down the column of tubes would cause similar disadvantages since the distance from the drive rod to the hydraulic clamp is also fixed. So there is currently no totally satisfactory solution in practice.

The present invention improves the situation. It will be described in the case of modern wellhead devices, in accordance with the block diagram of Figure 3, that is to say, at the top engine "top drive". The applicant has engaged in a thorough examination of the practical operation of the elements used in the crowded environment of a wellhead. Known solutions are limited by the fact that those skilled in the art will not modify, in principle, a security organ, at least substantially. Thus, in the second solution mentioned above, the rotary joint has been installed in the wear component known as "saver sub", while the latter will encounter a dangerous environment for its rotary joint. Unexpectedly, the studies of the plaintiff have made it note that it is possible to incorporate a wireless communication device to a security valve type "kelly valve", contrary to what we could think a priori. This is now described with reference to FIGS. 6A and 6B. These FIGS. 6A and 6B show a safety valve which is here the LKV safety valve of FIG. 4. Conventionally, it comprises a tubular general structure, or body 600, with an internal thread 601 at one end (end). high in Figs. 6A and 6B) and an external thread 602 at its opposite end (low end in Figs. 6A and 6B). In the intermediate portion, a spherical ball 610 is pivotally movably mounted in a guide 611. The guide 611 is slidably inserted within the body 600 until it abuts on a shoulder 614. On the opposite side , the guide 611 is retained by a ring 618, housed in a peripheral groove arranged inside the body 600. The spherical ball 610 is pierced with a cylindrical channel 613 of the same geometry as the inside of the body 600. In the example shown, the pivoting of the ball can be controlled by means of an actuating key comprising a shape-matching hexagonal profile with an indentation 612 made in the spherical ball 610. The spherical ball 610 can be pivoted between a position where the channel 613 is in the axis of the body 600 and a position where the spherical ball 610 30 closes the inside of the body 600.

The Applicant has found that the low end of the LKV valve could be provided with a coupler 626, similar to those used in the column of drill pipes. This coupler 626 is connected to a first electrical connection 624 which borrows a longitudinal bore formed in the annular wall of the body 600 and a radial bore which extends at right angles to a recess 623 formed at the periphery of the body 600. This peripheral recess 623 on-board electronics 621 connected by a second electrical connection 625 to a set of antennas 627 housed in an annular groove 629 also formed at the periphery of the body 600. The second electrical connection 625 borrows a longitudinal bore formed in the annular wall of the body 600 and a radial bore which extends at right angles to the annular groove 629. The annular groove 629 is closed by a protection which is embodied here in the form of a cover 628 of non-metallic material, for example polytetrafluoroethylene ( PTFE). The recess 623 is closed by a protection which is made here in the form of a cover 630 of non-magnetic material, for example metal. The cover 630 is sealed to the body 600 by means of a seal (not shown) and a set of screws. The thickness of the protection is adapted so as to guarantee sufficient mechanical resistance to the pressure and the torque involved. The on-board electronics 621 and the antenna set 627 are part of a wireless communication device which allows, generally, the transmission of data from the drill string to a surface network and the reception of data from that surface network. The wireless communication device in question forms part of what may be called a surface interface. In the embodiment of FIG. 6A, the communication device embedded in the body 600 is intended to cooperate with at least one wire antenna 631, for example a slotted radiating cable, fixedly held in the wellhead apparatus. The wired antenna 631 extends there at least along the vertical excursion which the LKV valve undergoes therein repeatedly, together with the upper part of the column of tubes. This excursion can reach several tens of meters depending on the training technique used.

In the embodiment of FIG. 6B, the on-board communication device 600 is intended to cooperate with a surface communication device 632 which may be provided with an eyelet (not shown) through which a vertical cable passes. The surface communication device 632 may remain stationary at the base of the wellhead apparatus during the combined downward or upward and rotational movements of the LKV valve relative to the derrick 10. As shown in FIG. 4, the SavSub tubular element located below the LKV safety valve is normally a wear insert or "saver sub". The Applicant has observed that the two ends of this wear insert could be provided with communication couplers, while a connection between them passes along the wear insert, preferably in a conduit pierced in the wall of the housing. this one, from one end to the other. This is now described with reference to FIG. 14A. This FIG. 14A shows a wear insert which is here the SavSub wear insert of FIG. 4. In a conventional manner, the SavSub insert comprises a tubular general structure 1400 with a thread 1401 at the upper end, compatible with threading. 602 low end of the safety valve LKV, and a thread 1402 at the bottom end. The low end thread 1402 of the SavSub insert is compatible with the threads used in the lower part of the column of tubes. The low end of the SavSub insert is equipped with a 1426 coupler, similar to those used in the drill pipe column. The upper end of the SavSub insert is equipped with a coupler 1427, homologous to the coupler 626 of the LKV safety valve. Here, the high end coupler 1427 and the low end coupler 1426 of the SavSub insert are analogous. These couplers are interconnected by an electrical connection 1424 borrowing a longitudinal bore, provided here in the annular wall of the tube. In particular, the coupler 1426 of the bottom of the SavSub insert may be of the same dimensions as the couplers which are used in the drill pipe column, while the top 1427 coupler of the SavSub insert and the 626 coupler of the The bottom of the LKV valve can also be the same dimensions as those used in the drill pipe column. FIG. 14B shows an alternative embodiment of the SavSub insert which differs from that illustrated in FIG. 14A in that its upper end thread 1401 is of the male type, and not a female one. In this form, it is particularly suitable for an LKV valve whose 602 low end thread would be female type. As a result, the high end coupler 1427 is housed close to the corresponding end face of the SavSub insert, whereas, in the embodiment of FIG. 14A, this coupler 1427 is housed at the bottom of a bore provided for receive the low end of the LKV valve. In other words, in FIG. 14B, the high-end coupler 1427 is close to the end of the thread 1401 which is remote from the lower end of the SavSub insert, while in FIG. 14A this coupler 1427 is close to the end of the thread 1401 which is close to the low end of the SavSub insert. Reference is now made to Figure 7A. The set of antennas 627 comprises a plurality of elementary antennas 700-i (i integer from 1 to N, N being the number of antennas of said set), flat, which are printed on a substrate 702 and covered with a layer cover 704 made of a non-metallic material. The cover layer 704 may be different from the cover 628 (not shown in Fig. 7A). The elementary antennas 700-i are arranged regularly distributed around the axis of symmetry of the body 600. The right part of FIG. 7, which represents part of the set of antennas 627 in a developed form, shows, for example, for example, elementary antennas 700-i of elongate shape which are each inclined with respect to the longitudinal direction of the body 600 so that each end of an elementary antenna 700-i is approximately aligned, in the direction of the axis of symmetry of the body 600, with, each time, a respective end of an adjacent elementary antenna 700-i. With such an arrangement, the set of antennas 627 radiates substantially identically over the entire periphery of the body 600, at least over a longitudinal portion of the body 600 comprising the antenna set 627. By way of example, the Antenna set 627 here comprises eight elementary antennas 700-i (N = 8). According to an alternative embodiment illustrated in FIG. 7B, the elementary antennas 700-i are so-called planar antennas, also referred to as "patch antennas" in the art. These antennas make it possible to realize, in a small footprint, antennas having good directivity properties. Here, the planar antennas are slot coupled rectangular antennas connected in a network by a set of hybrid couplers (not shown).

FIG. 8 functionally illustrates a set of components 800 for the on-board electronics 621. The component set 800 comprises a first transmitter / receiver circuit 810 bidirectionally connected to the set of antennas 627 and which manages the communication between the set of components. antennas 627 and the fixed antenna installed on the wellhead apparatus, and a second transceiver circuit 804 in charge of bidirectional transmission of data with the on-board devices in the drill string, which devices are represented as a whole by the dashed frame with the reference 806. The set of components 800 also includes the memory 808, in which useful data can be stored, in particular data from the drill string to be transmitted to the surface network and data from this network to be routed in the drill string. For example, the memory 808 acts as a buffer. The set of components 800 further integrates one or more batteries 814 which supply all the elements of the onboard electronics 621, including a microcontroller 802 which operates all of these elements jointly. Optionally, the set of components 800 comprises a so-called local communication interface 810, connected to sensors embedded in the LKV valve and which measure operating characteristics of the onboard electronics 621 and / or the LKV valve 20 itself. These characteristics may include, without limitation, data on the vibratory conditions of the LKV valve, the pressure inside this valve, or temperature. Still optionally, the component set 800 comprises a configuration interface 818 through which the firmware of the microcontroller 802 can be updated and / or data recovered from the memory 808, and / or the on-board electronics 621, even the LKV valve itself, tested and / or configured, among other things. FIG. 9 functionally represents a surface electronics 900 which cooperates with one or more fixed antennas in order to communicate with the on-board device in the LKV valve. The surface electronics 900 also forms part of what has been called the surface interface.

The surface electronics 900 comprises a central computing unit 902 fed via a current transformer 904 connected to a power distribution network, which network is shown schematically by the dashed frame referenced 906. In replacement or in addition, the surface electronics 900 may be equipped with one or more batteries, ensuring the operation of the equipment in case of failure of the power distribution network. The surface electronics 900 integrates a transmit / receive circuit 908 which provides bi-directional digital type communication with the processing unit 902 and bidirectional communication with the antenna 910, which may be wired as in the embodiment of Figure 6A or other, for example according to the embodiment of Figure 6B. The surface electronics 900 further comprises an input / output interface, here Ethernet type, connected to a data exchange network shown schematically by the dashed block 914, and a configuration circuit 916 connected to the unit. 902 calculation and possibly accessible by an input / output interface of a standard type, for example USB (for "Universal Serial Bus" or "universal serial bus" in French). FIG. 10 shows a portion of the set of components 800 for transmitting / receiving data via the antenna set 627. The transmission lines of the elementary antenna differences 700-iy are respectively referenced 100_1, 100 2 , ..., 100_8. Each transmission line 100_i (i = 1, ..., 8) is connected to a respective switching channel of a switching circuit 102, an input / output channel of which is connected to an input / output channel. a switch 106 with two switching channels. The switching circuit 102 is capable of selectively connecting, here on command of a microcontroller 104, one or more of the transmission lines 100_i to the input / output of the switch 106. The switch 106 has a first switching path connected to a receiver line 107 and a second switching channel connected to a transmitting line 111. On command of the microcontroller 104, the switch 106 can switch from a first switching state in which the receiver line 107 is connected to the input channel / output of the switching circuit 102, the set of antennas 627 then operating in reception mode, to a second switching state in which it is the transmitting line 111 which is connected to the input / output channel of the switching circuit 102, the set of antennas 627 then operating in transmission mode. The switch 106, the receiver line 107 and the transmitting line 111 form a work electronics that is capable of working in transmit mode or receive mode, depending on the switch state of the switch 106. Although here the microcontroller 104 commands the Once the switching circuit 102 and the switch 106 have been used, it is possible, in a variant, to control these two devices by separate dedicated microcontrollers. The receiver line 107 comprises an amplifier-adapter 108 and a reception memory 110, while the transmitter line 111 comprises an amplifier-adapter 112 and a transmission memory 114. Although this is not shown in the figures, the amplifier-adapter 108 of the receiver line 107 and the amplifier-adapter 112 of the transmitting line 111 may be controlled by the microcontroller 104. The reception memory 110 and the transmission memory 114 may be organized within a same electronic device. This part of the set of components 800 further comprises a detection circuit 118 to which each of the transmission lines 100_1 to 100_8 are connected through a respective input. The detection circuit 118 is capable of establishing a signal representative of a reception power as measured, at its inputs, on each of the transmission lines 100_1 to 100_8 corresponding to the elementary antennas 700-i of the antenna set 627. , and, if necessary, to output this signal, here to the microcontroller 104. Figure 11 illustrates the operation of the on-board electronics, as regards the transmission and reception of data. In an operation 1100, the on-board electronics 800 is initialized, at least with respect to the elements described in connection with FIG. 10. The transmission chain is in reception mode (the switch 106 is on the receiver line 107). The signal obtained from the detection circuit 118 is acquired. In an operation 1102, it is checked whether the set of antennas is at least partially operational, that is to say that at least one of the antenna elements is capable of receiving a signal from the fixed antenna. For example, it is verified that the detection circuit 118 measures a reception power value greater than a threshold value for at least one of the elementary antennas 700. Otherwise, the operation 1102 is restarted until an antenna at least be operational.

When the test of the operation 1102 is positive, the reception of a data packet and the transmission of another data packet are organized during an operation 1104. Then a processing is carried out on the received data and / or the data to be transmitted in the next transmission / reception step, during an operation 1106. During this processing operation, it is verified in particular that the received data packet is intact, in other words that the received data form a complete package. Encapsulation of packet data for transmission is also provided. This succession of operations can be performed in the form of a function of a microprogram executed by the microcontroller 104. However, nothing prevents an embodiment from exclusively logic electronic circuits.

Figure 12 details the operation of transmitting and receiving a data packet. This operation begins with an initialization step 1200. This initialization step comprises in particular a synchronization phase between the onboard electronics 800 and the surface electronics 900 to define respective time windows for transmission and reception. a packet of data. In step 1202, the on-board electronics 800 is in a receiving state. This implies that the switch 106 is switched to the receive line 107, which can be further tested. In practice, the switch 106 has a default switching state that corresponds to the receive mode. The reception state also involves the putting into service of the amplifier-adapter 108. The received data are written in the reception memory 110. This reception step ends when a time period t_r, specified during the synchronization with the surface electronics 900, has elapsed. It will be seen later how this period can be advantageously evaluated. When the time t r is over, it is tested, at step 1204, whether there has been during the period 30 t r that has just elapsed. a change of state within the switching circuit 102.

If yes, then step 1202 is restarted. In other words, the on-board electronics 800 is in the data reception mode again, for a new time period t_r. The time t_r that this period of reception lasts can be the subject of a new synchronization. In other words, the duration of the reception time period can be adapted each time this step 1202 is restarted. This makes it possible to take into account the fact that the switching circuit 102 can be switched too frequently to allow the reception of a complete packet of data in the negotiated time period t_r. If the test of step 1204 is negative, then the on-board electronics is switched to transmission mode, in step 1208. This implies that the switch 106 is switched to its second switching channel and that the amplifier-adapter of the channel of emission is made operational. This packet sending step is completed when a time period t_s, the duration of which has been negotiated during the previous synchronization step, has elapsed.

When the time period t_s has elapsed, it is tested whether there has been a switch within the switch 102 during this time interval, at step 1210. If yes, then the transmission step 1208 is restarted. for a new time period t_s, of duration equal to or different from the previous time period t_s. If the interval t_s has elapsed without switching, then the set of antennas 627 is switched to receive mode, in step 1212, i.e., the microcontroller 104 emits a switching signal to the switch 106 which connects the receive line 107 to the input / output channel of the switching circuit 102. The steps just described can be performed by executing a function Microcontroller microprogram 104. FIG. 13 illustrates the operation of the on-board electronics, with respect to the switching of elementary antennas 700-i of the antenna set 627. After an initialization operation 1300, it is tested whether the set of antennas is at least partially operational during a step 1302. This test consists in particular in verifying that a minimum reception power can be measured on at least one of the transmission lines 100_i 0 = 1, ..., 8).

If the test of the operation 1302 is negative, then the operation 1302 is repeated until it is positive, if necessary after the delay. In operation 1304, one or more selection criteria are evaluated for all the elementary antennas 700-i judged operational. At this time, it is sought to determine the most efficient antenna or antennas for communication. According to one embodiment, the antenna line 100_i on which the largest reception power is measured is selected. In this embodiment, the available transmission power is concentrated on a single elementary antenna 700, which makes it possible to be very efficient in terms of speed and energy saving. Alternatively, a subset of transmission lines could be selected, for example, all transmission lines on which a reception power greater than a predetermined floor value is measured. In yet another variant, it would also be possible to select the line on which the largest reception power is measured, or several lines on which the largest reception powers, that is to say greater than the powers, are measured. received on the other lines. In this case, the selection may be conditioned by the fact that the reception power measured on the selected lines is greater than a floor power value. The selected antenna or antennas may also include one or more elementary antennas adjacent to the antenna corresponding to the transmission line on which the largest reception power has been measured, especially if several fixed antennas are used on the surface. According to yet another variant, the power levels measured by the detection circuit 118 may be taken into account only in a secondary manner for the selection of the elementary antenna or antennas. For example, the active elementary antenna at the present time being identified (for example by means of a memory register), the elementary antenna selected in the operation 1304 may be the antenna adjacent to the current antenna (lower or higher identifier) on the transmission line which is measured the largest power of reception. Still for example, the elementary antenna 30 currently active and a direction of rotation of the body 600 (known from the extrapolation of the evolution of the reception power of an antenna line, typically the corresponding antenna line at the presently activated antenna, and the evolution of the slope) being known, the antenna selected in the course of the operation 1304 may be the next antenna (of lower or higher identification number), provided that the measured reception power is greater than a threshold value. In operation 1306, the switching circuit 102 is controlled to connect the switching channels corresponding to the transmission lines of the selected antennas to its input / output channel. In step 1308, it is tested whether one or more switching conditions are met. These switching conditions aim to determine when it is appropriate to make a modification in the set of active antennas. A first condition may include evaluating the reception power of the currently active antenna and comparing the measured power level to a floor value, this first condition being fulfilled if the measured power is less than the floor value. A second condition may include comparing the reception powers measured on the transmission lines corresponding to a subset of the set of antennas 700. For example, the second condition is fulfilled if there is a transmission line, different from the line corresponding to the currently active antenna, on which a higher reception power is measured at the line of the antenna 20 currently activated. A third condition may include the flow of a specified time period, for example, evaluated on the basis of a rotational speed of the body 600. The operation 1308 is restarted as long as the switching conditions are not fulfilled. The operations described in connection with FIG. 12 can be implemented by the execution of one or more functions of the firmware of the microcontroller 104, of a microcontroller dedicated to the control of the detection circuit and of the switching circuit 102 and / or a specific circuit. The detection circuit 118, together with the microcontroller 104 with which it exchanges data, acts in the manner of an elementary antenna monitor which repetitively evaluates the reception power of each of these elementary antennas as a quantity of quality. receiving circuit, or a subset of the set of antennas 627. The detection circuit 118, together with the microcontroller 104, repeatedly select one or more elementary antennas of said set according to the reception quality variables from said subset and control the switching circuit 102, which acts as an actuator, to connect the antenna or antennas so selected what may be called a work electronics, that is to say the transmitter lines 111 and receiver 108 Returning now to the processing step described above in relation to FIG.

Thanks to the regular distribution of elementary antennas 700-i around the axis of symmetry of the body 600, which corresponds to its axis of rotation when the drill string is in use, it is possible at any time to ensure a level of power greater than a floor level in transmission as in reception, at least in normal operation of the surface interface. By switching repetitively the elementary antennas active on the one or the most efficient over a period of time, it ensures a saving of the energy consumed by the data transmission. In other words, we have made elementary antennas directives that can be controlled to limit energy losses. On this point, the use of high transmission frequencies, for example of the order of 2.45 GHz, further improves the directivity of the elementary antennas.

The minimum power level is maintained through more or less regular, selective and conditional switching of active elementary antennas. The switching frequency depends on many parameters, in particular on the evolution of the radiofrequency wave propagation conditions in the wellhead apparatus, conditions which are likely to be influenced by many rather unpredictable parameters, such as the presence of tooling between the body 600 and the fixed antenna for example. It should be noted that the negative effect of these unpredictable phenomena on the transmission is minimized by the fact that the most efficient elementary antenna or antennas is usually switched (and not necessarily that which is in front of the fixed antenna).

The rotation speed of the body 600 relative to the fixed antenna can influence the switching frequency of the elementary antennas 700, and therefore the duration of the time window actually available for the transmission and reception of data. Given a threshold transmission power level, beyond which it is considered that data transmission is appropriate, the increase in the rotation speed of the drill string tends to decrease the time window actually available for an elementary antenna. , while the decrease in this speed tends to increase this time window. The processing performed on the data packets can be advantageously adapted to take this into account. In one embodiment, the data to be transmitted is encapsulated in packets whose size is likely to vary over time, depending on the switching frequency, which can be evaluated on the basis of a history (an average of switching frequency, eg a time interval), or that of a rotational speed. In other words, the size of the transmitted and received packets is adapted according to the time window offered each time by an elementary antenna 700. It is also possible to provide fixed size packets. The size of the packets can then be estimated on the basis of a maximum rotation speed of the drill string, whether real (for example 120 revolutions per minute) or theoretical (for example 250 revolutions per minute). Within a time window, it is necessary to organize at least one interval for reception, of duration tr, and an interval for transmission, of duration t _s. These times t_r and t _s can be deduced, if necessary, from the time window available on an elementary antenna 700, whether the duration of this window is known, estimated, measured, or assumed. The times t _s and tr are not necessarily identical to each other since, in the application described here, the information to be extracted from the drill string is larger in quantity than the information to be transmitted to this drill. column. As we have seen, the solution proposed here proceeds from a complete questioning of the usual ideas of the person skilled in the art. This occurs first of all because a communication device is provided on a security element, namely a valve.

On the contrary, the known solutions, in particular US 2010/0224409, place the rotary joint on the wear insert, while it will be close to mechanical members working in force, such as hydraulic clamp-lock ( "hydraulic clamp"). This results in a serious risk of damage to the communication device, and for its connection cable with the surface interface, so inadvertent service interruption. In addition, it is usual to periodically "recondition" the threads of the wear insert. The presence on it of a communication device can pose a problem, if one wants to achieve the repackaging of its threads at acceptable economic conditions. The alternative of making the wear component a disposable component is not necessarily desirable either economically. US 2010/0224409 proposes to make a communication device at least partly removable, but this makes it even more complex to manufacture the wear insert. The solution proposed here avoids this problem. The wear insert is equipped with end couplers and a cable, in a manner similar to what is done for the tubes of the drill string. It does not include the outer projection that constitutes the rotary joint. It is therefore possible to repackage the threads of the wear insert by the same techniques as those used for the tubes of the drill string. The wear insert retains its qualities of mechanical strength, critical at this point of the column. The cost of repackaging the wear insert is optimized compared to the solutions known as "Data Swivel" and "SwivelLink". The wear insert maintains a small external footprint. The prediction of the communication device on the valve LKV also makes it possible to have on this valve at least two possible clamping positions, namely above and below the set of antennas, because of the length of the this valve. As explained above, the invention is not limited to the case of drilling by motor at the top, but can also be considered in combination with a profiled stem type "kelly". In this case, the LKV valve described here could be used as an "upper kelly valve", while the "kelly" shaped stem, the "lower kelly valve" and the lower wear insert (" lower saver sub ") could each be equipped with end couplers and a cable electrically connecting these couplers.

The described LKV valve could also be arranged as a pneumatic valve. Although the communication device which has just been described has many advantages when it is integrated with a "kelly" valve, at least some of these advantages can be found once the device in question becomes is embedded in an axially symmetrical drill pipe element. The described device saves substantially the energy consumed by the data transmission operations. This is of particular importance in the field of drilling, because the device in question, as all the electrical devices embedded in the drill string, must be autonomous and are therefore powered by on-board batteries. However the depletion of a battery can have particularly harmful consequences, because its replacement requires the stop of the production and / or drilling. More precisely, the device proposed here offers optimal management of the energy dedicated to the transmission of data, since all the available power is always attributed to the antenna, or to a subset of the antenna set, the most efficient, the other antennas being rendered passive. This is further enhanced by the use of highly directional antennas, which effectively select the antenna or antennas to be used at a given time. It should be noted that, although at any time only a part of the antenna set is activated, it is possible to obtain, thanks to the proposed device, a substantially continuous data transmission, even in the case of the use of an antenna. single fixed antenna. This transmission can be done at higher speeds, and with remarkable energy performance. The proposed device also allows data transmission of TDMA type, for "Time Division Multiple Access", or "time division multiple access" in French.

Claims (19)

REVENDICATIONS1. A drill string element of the type comprising a body (600) of general axisymmetric appearance and a wave communication device embedded in said body (600), characterized in that the communication device comprises: - a set of antennas (627) comprising a plurality of antennas (700-1, 700-2, 700-i) distributed at the periphery of said body (600), about the axis of symmetry thereof, and capable of operating in transmission and reception; a work electronics (122) capable of organizing data transfers, transmitting and receiving; an actuator (102) capable of selectively connecting the antennas of said game to the work electronics; an antenna monitor (118) arranged to regularly evaluate a reception quality magnitude for at least one subset of the antenna set (627), repetitively selecting one or more antennas (700-1, 700-2, 700 i) of said set according to the reception quality variables from said subset and controlling the actuator (102) to connect the antenna or antennas (700-1, 700-2, 700-i) thus selected to the work electronics (122). 2. Element according to claim 1, wherein the antenna or antennas (700-1, 700-2, 700-i) selected comprise one or more antennas among said subset 20 and / or one or more antennas adjacent antennas of said subset. 3. Element according to one of claims 1 and 2, wherein the antenna monitor (118) is further arranged to regularly evaluate a switching criterion and control the actuator (102) each time the switching criterion is checked. The element of claim 3, wherein the switching criterion comprises a comparison between a time elapsed since the last activation and a predetermined duration. An element according to claim 4, wherein said predetermined time is calculated from a rotational speed value of said body (600), taking into account the distribution of the antennas (700-1, 700-2, 700- i) about the axis of symmetry of the body (600). 29 6. Element according to claim 5, wherein the rotational speed value is determined from the time evolution of the reception quality quantity of at least one of the activated antennas. Element according to one of claims 3 to 6, wherein the switching criterion comprises a comparison of substantially instantaneous values of reception quality variables relating to the activated antennas (700-1, 700-2, 700-i). on the one hand and on the other hand, to the other antennas (700-1, 700-2, 700-i) of said subset. The element of one of the preceding claims, wherein the work electronics (122) is capable of repeatedly switching between a receive mode and a transmit mode. 9. Element according to claim 8, wherein the working electronics (122) is arranged to operate in transmission mode for a period of time of a determined duration and to switch to transmission mode in the absence of modification of the 15 antennas (700-1, 700-2, 700-i) connected to it during said time period. 10. Element according to one of the preceding claims, wherein the set of antennas (627) comprises a plurality of surface antennas regularly distributed around the axis of symmetry of said body (600). 11. Element according to one of the preceding claims, wherein said body (600) 20 houses a safety valve. 12. Device for wellbore head, comprising at least one element according to one of the preceding claims. The device of claim 12, wherein the body of the member has a high end thread (601), a low end thread (602), an end coupler (626), arranged at its end. low end, adapted to cooperate with a homologous end coupler of another element screwed to the low end thread (602), and an electrical connection (624) arranged between the end coupler (626) and the work electronics (122). The apparatus of claim 13 further comprising a valve (610) disposed at an intermediate portion of the body (600) between the upper end thread (601) and the lower end thread (602). 15. Drill well head comprising at least one device according to one of claims 12 to 14 integral with a drive (TD) in rotation relative to a derrick (10) and one or more fixed antennas (631, 632) compared to this derrick (10). A method of communicating using a drill string element comprising a generally axisymmetric body (600) and an antenna set (627), comprising a plurality of antennas (700-1, 700). -2, 700-i) distributed at the periphery of said body (600), about its axis of symmetry, and capable of operating in transmission and reception, comprising the following steps: a. evaluating at least one receive quality magnitude for at least one sub-set of the antenna set; b. selecting one or more antennas of said set according to the one or more reception quality variables from said subset; vs. organize a transfer of data, in transmission and / or reception, via the selected antenna or antennas. 15 17. The method of claim 16, wherein the evaluation step is carried out regularly. 18. Method according to one of claims 16 and 17, wherein the selection step is carried out repetitively. 19. A method of drilling, exploring and / or operating a hydrocarbon well comprising one or more communications implemented in accordance with the method of one of claims 16 to 18.