OA19061A - Pipe for cableless bidirectional data transmission and the continuous circulation of stabilizing fluid in a well for the extraction of formation fluids and a pipe string comprising at least one of said pipes. - Google Patents

Abstract

Pipe for cableless bidirectional data transmission and the continuous circulation (50) of a stabilizing fluid in a well for the extraction of formation fluids comprising: a hollow tubular body (51) which extends in length along a longitudinal direction X and which is configured at the ends for being coupled with respective drill or completion pipes (11); a radial valve (52) associated with the tubular body (51), the radial valve (52) being connectable to a pumping system (40) outside the tubular body (51); an axial valve (53) associated with the tubular body (51); a communication module (20) associated with the tubular body (51) comprising at least one metal plate selected from a transmitting metal plate (21), a receiving metal plate (22), a transceiver metal plate (35) ; an electronic processing and control unit (23) configured for processing signals to be transmitted by means of the at least one metal plate (21, 35) or signals received by means of the at least one metal plate (22, 35); one or more supply batteries (24) for feeding the metal plates (21, 22, 35) and the electronic processing and control unit (23).

Description

PIPE FOR CABLELESS BIDIRECTIONAL DATA TRANSMISSION AND THE CONTINUONS CIRCULATION OF STABILIZING FLUID IN A WELL FOR THE EXTRACTION OF FORMATION FLUIDS AND A PIPE STRING COMPRISING AT LEAST ONE OF SAID PIPES

The present invention relates to a pipe for cablëless bidirectional data transmission and the continuons circulation of stabilizing fluid in a well for the extraction of formation fluids, for example 10 hydrocarbons.

The present invention also relates to a pipe string comprising at least one of said pipes.

A well for the extraction of formation fluids can be assimilated to a duct having a substantially 15 circular section or, in other words, a long pipeline.

As is known, rotary drilling involves the use of a drill pipe string for transmitting a rotary motion to a drill bit, and the pumping of a stabilizing fluid into the well through the same pipe string.

The pipe string typically comprises a plurality of drill pipes connected in succession with each other; in particular, the pipes are typically divided into groups of three and each group of three pipes is commonly called stand.

25--------Ever since the conception of—this—type of drilling, there has been the problem of interrupting the pumping process each time a new pipe or other element in the . string must be added. This time transition, identifiable from the moment in which the pumping of 30 fluid into the well is interrupted until the pumping action into the well is resumed, has always been considered a critical period. This critical condition remains until the condition existing prior to the interruption of the pumping of fluid into the well, has been re-established.

The interruption of the circulation of fluid into the well, during the insertion and connection, or disconnection process of an element in the drill string, can cause the fôTlowing drawbacksh

- the dynamic pressure induced in the well by the circulation fails and its effect conventionally defined

ECD (Equivalent Circulating Density) is reduced;

- the dynamic pressure induced at the well bottom is zeroed, favouring the potential entry of layer fluids into the well (kick);

- with the resumption of the circulation, annoying overloads of the most réceptive formations can arise, or potential circulation losses in the weaker formations ;

- in wells having a high verticality, the unobstructed and rapid fallout of drill· cuttings can cause mechanical grip conditions of the drill string (BHA);

- in the presence of wells with a high angle of inclination, in extended reach wells and in wells with a horizontal development, the drill cuttings hâve time to settle on the low part of the hole; consequently

--when the drilling in ro-Dtartod,—after the insertion of a new pipe, the drill bit is forced to re-drill the bed of cuttings deposited at the well bottom, before being able to reach the virgin formation again.

In order to overcome the drawbacks mentioned above, the idea was conceived of interposing between consecutive pipes, more preferably between consecutive stands, a pipe having a shorter length with respect to common drill pipes and equipped with a valve system for continuons circulation.

Patent US 7,845,433 B2 describes an embodiment of a pipe for continuons circulation which allows the 5 pumping to be kept uninterruptedly active and therefore the circulation of fluid in the well, during ail the operating steps necessary for effecting the adcTition o'f” a new pipe into the pipe string in order to drill to a greater depth.

During the varions drilling phases, moreover, and in particular during the phases for changing or adding a pipe in the string, data must be received in real time from sensors positioned at the well bottom and/or along the whole pipe string.

Varions Systems are currently known for bidirectional data transmission from and to the well bottom, more specifically from and to the well-bottom equipment, hereinafter called downhole tools. The current Systems are mainly based on:

- a technology of the so-called mud-pulser type, which is based on the transmission of a pressure puise generated with a defined sequence through the drilling fluid present in the well during ail the drilling operations;

T5--=—a—technology—crf—Lhe . so-called—wired—pipe—type, which consists of a particular type of wired pipes for which the electric continuity between adjacent pipes is ensured by a contact element arranged on the connection thread between the pipes themselves, 30 According to this wired pipe technology, the data are therefore transmitted on wired connections;

- a so-called acoustic telemetry technology based on the transmission of acoustic waves along the drill pipes;

- a so-called through-the-ground technology based on electromagnetic transmission through the ground.

Each of these technologies has some drawbacks.

The mud-pulser technology, in fact, has limits fëTâ/Eing to tïïen:ransmissiormratre^-arrd^-rednrab±±±ty—as rt— may be necessary to transmit the same signal various times before it is correctly received. The transmission 10 capacity of this technology dépends on the characteristics of the drilling fluid and the circulation flow-rate of said fluid.

The wired pipe technology is affected by extremely high costs as the wired pipes are very 15 expensive; furthermore, every time a pipe must be added to the drill string, the wired connection is interrupted, thus preventing communication from and towards the well bottom during these operations.

The acoustic telemetry technology is affected by 20 potential transmission errors due to the operating noise of the drill bit or déviation of the wells from perfect verticality.

Due to the low frequencies used for covering transmission distances in the order of kilométrés, the -2-5 through tho-ground--technology—ls affected----an.

extremely low transmission rate (équivalent to that of the mud puiser⁷' technology) and reliability problems due to the crossing of various formation layers with different electromagnetic propagation characteristics.

The objective of the present invention is to overcome the drawbacks mentioned above and in particular to conceive a pipe for cableless bidirectional data transmission and for the continuous circulation of a stabilizing fluid in a well for the extraction of formation fluids and a pipe string, which are able to ensure, at the same time, the continuous 5 circulation of the fluid during operations for changing or adding pipes and the continuous transmission in real time of a high amount of esta from and towards trie well bottom, which is independent of the operating conditions of the drill string, the drilling fluid 10 présent in a well and the circulation flow-rate of said fluid.

This and other objectives according to the présent invention are achieved by providing a pipe for cableless bidirectional data transmission and for the 15 continuous circulation of a stabilizing fluid in a well for the extraction of formation fluids and a pipe string as specified in the Independent daims.

Further features of the pipe for cableless bidirectional data transmission and for the continuous 20 circulation of a stabilizing fluid in a well for the extraction of formation fluids and the pipe string, are object of the dépendent daims.

The characteristics and advantages of a pipe for cableless bidirectional data transmission and for the 25--continuous circulation of a stabilizing fluid in a well for the extraction of formation fluids and a pipe string according to the présent invention will appear more évident from the following illustrative and nonlimiting description, referring to the enclosed 30 schematic drawings, in which:

- figure 1 is a schematic view of a drilling rig for the extraction of hydrocarbons comprising a pipe string according to the present invention;

- figure 2 is a partial sectional schematic view of an embodiment of a pipe string according to the present invention;

- figure 3a is a schematic view of a first operational configuration of a first embodiment of a pipe for cableless bidirectional data transmission and for continuous circulation according to the present

invention ;

10 - figure 3b is a view of a detail of figure 3a framed

by dashed lines;

- figure 3c is a schematic view of a first operational

configuration of a second embodiment of a pipe for

cableless bidirectional data transmission and for 15 continuous circulation according to the present invention;

- figure 4a shows a connection between a pipe for cableless bidirectional data transmission and for continuous circulation according to the present invention and a pumping System included in the drilling rig of figure 1;

- figure 4b is a view of a detail of figure 4a;

- figure 5 is a schematic view which represents two communication modules provided with transmitting and

A5--receiving—me Lal—plates—arrd—huused—rn—twO—pipes—fcrr cableless bidirectional data transmission and continuous circulation of the same pipe string; figure also illustrâtes examples of current flow lines between the two modules;

- figure 6a is a block diagram which represents a communication module connected to a plurality of sensors;

- figure 6b is a block diagram which representsa communication module acting as a repeater;

- figure 6c is a block diagram which representsa communication module acting as a regenerator;

- figure 7 is a circuit diagram which representsa model for the configuration of figure 5;

-------figure—8—is—a—sehematrc—vrew—which—represents—two — communication modules provided with transmittîng and receiving coils and housed in two pipes for cableless 10 bidirectional data transmission and continuous circulation of the same pipe string; figure 8 also illustrâtes examples of magnetic field flow lines between the two communication modules;

- figure 9 is a graph which represents the distribution 15 of the magnetic field intensity between two communication modules such as those of figure 8.

With reference in particular to figure 1, this schematically shows a generic well for the extraction of formation fluids, such as, for example, hydrocarbons. The well is indicated as a whole with the reference number 10.

The well 10 is obtained by means of a drilling rig which comprises a pipe string 60 according to the present invention.

.£§--------The pipe string 60 can be a dri 1 1—string or also a— completion pipe string used during the production steps of the well 10.

The pipe string in any case comprises a plurality of pipes 11, 50 connected to each other in succession, 30 which extends from the surface as far as the well bottom 10. A bit 13 or other excavation or drilling tool can be connected to the lower end of the pipe

string. The pipes 11, 50 can be hollow and hâve a substantially circular section; said pipes, when connected to each other in succession, therefore create 5 an internai duct as shown for example in figures 3a. and 3b. The drilling rig comprises a pumping system 40,
also called rig pump manifold, associated with the pipe strincr 60 suitable for pumping stabilizing fluid inside
the internai duct, generating a primary flow directed 10 towards the bottom of the well. The stabilizing fluid therefore crosses the pipe string 60 untii it exits . close to the bit 13. The pipe string 60 can be associated with a plurality of sensors 14, so-called MWD {Measurement 15 While Drilling), that can be positioned along the string and in particular in correspondance with the well bottom 10. Said MWD sensors 14 are configured for continuously detecting a plurality of parameters relating to the fluids circulating in the well and' the 20 rock formation surrounding the well 10. These MWD sensors 14 can, for example, be density or resistivity sensors configured for continuously measuring, respectively, the density value and the resistivity value of the drilling fluid and so forth. The pipe
25 sLring où can also be 73.:01:14 Led wj.L1l safeLy Lcviu-ù uJ.

other remote-controlled well instrumentation (not shown),

The plurality of pipes 11, 50 comprises a plurality of drill or completion pipes 11 and a plurality of 30 pipes for cableless bidirectional data transmission and continuons circulation 50 according to the present invention. Said pipes for cableless bidirectional data transmission and continuons circulation 50 hâve a length, for example ranging from 50 to 200 cm, shorter than that of the drill or completion pipes 11.

The pipes for cableless bidirectional data transmission and continuous circulation 50 . are positioned along the pipe string 60 between two drill --or—cunipl^_et±OTi—pipes—1^_1—at—pre^estebÜshed—rntervais—crf— one or more drill or completion pipes 11.

The pipes for cableless bidirectional data transmission and continuous circulation 50 are preferably positioned along the pipe string at intervals of three drill or completion pipes.

In this case, the groups of three drill or completion pipes interconnected with each other are 15 commonly called stands.

The pipe for cableless bidirectional data transmission and continuous circulation 50 advantageously has a hollow tubular body 51 which extends in length along a longitudinal direction X and 20 which is configured at the ends for being coupled with respective drill or completion pipes 11. This coupling can, for example, be of the threaded type or prismatic type.

The tubular body 51 is provided with a radial valve 25 52 configured for regulating the fl ow of a fluid i û a substantially radial or transversal direction with respect to the longitudinal direction X and an axial valve 53 configured for regulating the flow of a fluid along said longitudinal direction X. In particular, the 30 axial valve 53 is configured for regulating the flow of primary fluid pumped from the pumping system. The radial valve 52 can be advantageously connected to the pumping System 40 outside the tubular body 51. Said radial valve 52 is preferably connected to said pumping system 40 by means of a connector or adaptor coupled with a flexible pipe 41 fed by the pumping system 5 itself.

The radial valve 52 is preferably provided with a safety cap, preferably pressure-tight.

The radial valve 52 and the axial valve 53 are more preferably butterfly valves.

The radial valve 52 and the axial valve 53 are more preferably butterfly valves preloaded with springs.

During the drilling, the radial valve 52 is advantageously kept closed with the safety cap whereas

the axial valve 53 is kept	open so as to	allow	the
15 passage of	the stabilizing	fluid	towards	the	well
bottom.
When a	further pipe 11	must be	added to	the	Pipe
string, the	intervention is	effected on the	pipe	for
cableless	bidirectional	data	transmission	and

continuous circulation 50 closest to the surface, as follows. The pumping System . is connected to the radial valve 52 by means of the flexible pipe 41, for example, and the flow of primary fluid through the injection head at the inlet of the pipe string 60, is

--interrupted.—Tire—axial—valve—55—rs—closed,—tire—radial valve 52 is opened and the flow of secondary fluid through the flexible pipe 41, is activated. At this point, a new pipe 11 can be inserted in the pipe string 60 above the connecting pipe 50 connected to the 30 pumping System. Once the pipe string 60 has been assembled with the new pipe, the radial valve 52 is closed, the axial valve 53 is opened and the flow of primary fluid is restored through the supply of the injection head of the pipe string 60.

The pipe for cableless bidirectional data transmission and continuons circulation 50, according 5 to the présent invention, also comprises a communication module 20 associated with the tubular body 51.

As can be seen in figure 3a, the tubular body 51 preferably has a first longitudinal portion for 10 continuons circulation with which the radial valve 52 and the axial valve 53 are associated, and a second longitudinal portion for cableless bidirectional data transmission with which the communication module 20 is associated.

in this case, the first and the second longitudinal portions are consecutive with respect to each other.

According to an alternative embodiment illustrated in figure 3c, the first longitudinal portion for continuons circulation and the second longitudinal 20 portion for cableless bidirectional data transmission are partially superimposed. In this case, some housings for the communication module can be produced in correspondence with the first longitudinal portion for continuons circulation so as to obtain a more compact “75 cohf iguraLlun—with—respect—te—tfee—PÙP^e——cabl el pss bidirectional data transmission and continuous circulation 50 of figure 3a.

According to the présent invention, each communication module 20 comprises:

- at least one métal plate 21, 22, 35 selected from:

- a transmitting métal plate 21;

- a receiving métal plate 22

Ο

- a transceiver métal plate 35;

- an electronic processing and control unit 23, for example comprising a microprocessor, configured for processing signais to be transmitted by means of the at least one métal plate 21, 35 or signais received by means of the at least one métal plate 22, 35;

- one br more supply batteries 24 for feieding tire” métal plates 21, 22, 35 and the electronic processing and control unit 23.

In each communication module 20, the métal plates

21, 22, 35 are advantageously electrically insulated from the metallic body of the connecting pipes 50.

In this way an electric contact between the métal plates 21, 22, 35 and the metallic body of the connecting pipes 50 is avoided.

The métal plates 21, 22, 35 are preferably arcshaped.

In a particular embodiment of the présent invention, each communication module 20 comprises two 20 transmitting métal plates 21 and/or two receiving métal plates 22 .

If the communication module 20 comprises a transceiver métal plate 35, the receiving and transmitting operations, even if simultaneous, are --offoctod—is—su 1 tab 1 y—separate—frequency—bands This allows, for the same overall dimensions, the size of the plate to be increased, improving the transmission and réception efficiency.

In addition to the at least one métal plate 21, 22,

35, as illustrated in figures 3a, 3b, 3c and 4b, each communication module 20 can comprise at least one transmitting coil 25 and at least one receiving coil

26, coaxial to each other and coaxial with respect to the longitudinal axis of the pipe for cableless bidirectional data transmission and continuons circulation 50 with which they are assocîated.

More specifically, the at least one transmitting coil 25 has a few turns, for example in the order of tens, and a conductor with a large diameter, for example larger than 1 mm, in order to maximize the current flowing through the conductor itself and 10 therefore the magnetic field proportional to it, and minimize the power dissipation.

The at least one receiving coil 26, on the other hand, has a high number of turns, for example in the order of a few thousands, in order to contain the 15 ' signal amplification gain within reachable practical limits and improve the amplification performances.

The at least one transmitting coil· 25 and the at least one receiving coil 26 are preferabiy superimposed on each other, as illustrated in figures 3a, 3b, 3c. and 20 4b, in order to limit the encumbrance along the longitudinal axis of the pipe for cableless bidirectional data transmission and continuons circulation 50 with which they are assocîated.

The supply batteries and electronic processing and -25---coilLrol—uniL——can preferabiy be housed in one or more housings; in the embodiment illustrated in detail in figure 3b, the supply batteries and electronic processing and control unit 23 are housed in a first housing 54, whereas the métal plate 21, 22, 35 and coils 25, 26 are housed in a second housing 55. The housings 54 assigned for housing the batteries and electronic processing and control unit 23 are closed towards the outside of the pipe for cableless bidirectional data transmission and continuous circulation 50; they are in fact produced by compartments inside the pipe.

The housings 55 of the coils 25, 26 and métal plates 21, 22, 35, on the other hand, are open towards -the outside οΐ the pipe, as they are formed by reçusses in the side surface of the pipe for cableless bidirectional data transmission and continuous 10 circulation 50, as can be seen in figure 3b.

In particular, the coils 25, 26 are wound around the pipe for cableless bidirectional data transmission and continuous circulation 50 in correspondance with the recesses 55 and afterwards, the at least one métal 15 plate 21, 22, 35 is arranged in a position facing the outside so that, during normal use, it is in direct contact with the fiuids circulating in the well.

In the particular embodiment illustrated in figure 3a, the first housing 54 and the second housing 55 are 20 produced in a longitudinal direction beneath the first longitudinal portion for continuous circulation, in particular beneath the radial valve 52.

In the embodiment illustrated in figure 3c, on the contrary, the first housing 54 is formed in -2-5--correspondance—with—the—radial—valve—52—whereas—the second housing 55 is formed in correspondence with the axial valve 53.

The communication between two consecutive communication modules 20 of the pipe string 60 can 30 therefore take place using the electric current injected into the mud from the transmitting métal plate 21 or transceiver métal plate 35 of one module and captured by the receiving métal plate 22 or transceiver métal plate 35 of the subséquent module, and/or a magnetic field generated by the coil 25 of one module and concatenated by the coil 2 6 of the subséquent 5 module.

In any case, the communication modules 20 can be configured for acting as transmilfters anci/or receivers' and/or repeaters and/or regenerators.

In particular, if the single communication module 10 20 is configured for acting as a signal transmitter, for example as in figure 6a, the electronic processing and control unit 23 is configured for acquiring and processing the détection data from the sensors 14 or the control signais for the safety devices and other well-bottom instruments. In this case, the electronic processing and control unit 23 comprises a data acquisition module 27 which is configured for creating data packets to be transmitted, a coding module 28 for encoding said data packets, modulation circuits 29 for modulating the signais corresponding to the encoded data packets and output amplification circuits 30 for amplifying the modulated signais and. feeding the transmitting métal plate 21 or transceiver métal plate 35 and/or the transmitting coil 25.

25--------Correspondingly,----a--communication—module--2-Θconfigured for acting as signal receiver, the electronic processing and control unit 23 comprises an input amplification circuit 31 for amplifying the signal received from the receiving meta! plate 22 or 30 transceiver métal plate 35 and/or from the receiving coil 26, démodulation circuits 32 of said signal received and amplifîed and a decoding module 33 of the demodulated signal.

In a communication module 20 configured for acting as signal repeater as, for example, in figure 6b, the electronic processing and control unit 23 comprises 5 input amplification circuits 31 for amplifying the signal received from the receiving métal plate 22 or transceiver métal plate 35 or from tlïë receiving côiï“ 26, circuits for re-modulating 34 the signal to be retransmitted at a different carrier frequency with 10 respect to that of the signal received and output amplification circuits 30 for amplifying the remodulated signal. This modification of the carrier, effected by an analogue circuit, is required for preventing the communication module 20 from being 15 affected by the crosstalk phenomenon creating inévitable problème in the transfer of information.

In a communication module 20 configured for acting as signal regenerator as, for example, in figure 6c, the electronic processing and control unit 23 comprises 20 input amplification circuits 31 for amplifying the signal received from the receiving métal plate 22 or transceiver métal plate 35 or from the receiving coil 26, démodulation circuits of said signal received and amplified, a decoding module 33 of the demodulated ëë--signal,—a—coding—module—2-8——the—signal—previously decoded, modulation circuits 29 for re-modulating the signal to be retransmitted at a different carrier frequency with respect to that of the siqnal received (to prevent the communication module 20 from being 30 affected by the crosstalk phenomenon creating inévitable problems in the transfer of information) and output amplification circuits 30 for amplifying the re modulated signal.

More specifically, the data to be transmitted are organized in packets having a variable length, for example from 10 bits to 100 kbits. Each data packet can · undergo, for example, a source encoding process for the data compression and/or a channel encoding process for reducing the possibility of error. The modulation circuits 29 transform the single data packet into an appropriate signal with characteristics suitable for transmission inside the well 10.

An example of modulation used is DQPSK (Differential Quadrature Phase Shift Keying) , according to which a sinusoïdal signal is generated with a certain carrier frequency f, ranging, for example, from

1 to 30 kKz, whose phase varies according to the value of each sequence having a length of 2 bits; the phase can therefore acquire four values, for example (n/4, 3/4n, -n/4, -3/4n) . Each pair of bits can be mapped in the absolute phase of the sinusoid or in the relative phase différence (Differential QPSK) with respect to the sinusoid. corresponding to the previous pair of bits. This latter choice is préférable as it makes the inverse démodulation process simpler in the next communication module, as it will not be necessary to

25--estimdtë—the exacL value of—the frequency f due to—fcfye-------------fact that the error introduced by the lack of estimation can be eliminated by means of techniques known in the field. Furthermore, the waveform can be filtered with a suitable root raised cosine filter to limit the band occupation of the signal, with the same i transmission rates.

The modulated voltage signal thus obtained is amplified to voltages with values ranging, for example, from 1 to 100 V by the output amplification circuits 30 capable of supplying the current, with peak values ranging, for example, from 0.1 to 10 A.

The input amplification circuits 31 of . the subséquent communication module 20 transform the current flowing through the receiving metaZ^pTaTte 22 or transceiver 35 into a voltage signal with peak values of a few volts; these input amplification circuits 31, moreover, adapt the impédance of the receiving métal plate 22 or transceiver 35, preventing the voltage entering the subséquent device from being attenuated due to a divider effect.

In order to explain the transmission method 15 implemented by means of the métal plates 21, 22, 35, the exemplary case can be considered of the transmission from a first communication module 20 MCI, comprising a transmitting métal plate 21, to a second communication module 20 MC2, comprising a receiving 20 métal plate 22, as in the case illustrated in figure 5.

The considérations referring to this configuration can apply to the case of the transmission between two transceiver métal plates 35 or between a transmitting métal plate 21 and a transceiver métal plate 35. The -25---configuration--of--figure--5--is--schcmutizod--by--teheelectric diagram illustrated in figure 7 with the following considérations:

- the ground reference is given by the métal body, typically made of steel, the connecting pipes 50 which, 30 in the diagram, are considered as being idéal conductors;

- Vi indicates an electric potential which varies along the longitudinal axis of the well 10;

- li indicates an electric current which varies along the longitudinal axis of the well 10;

- VO indicates the electric potential produced by a transmitting métal plate 21;

- Zi, A indicates an infini t e s i ma 1 longi tudïnar electric impédance, which opposes the current flowing in a longitudinal direction, i.e. parallel to the longitudinal axis of the well 10;

- Zi, B indicates an infinitésimal radial electric impédance, which opposes the stream flowing in a radial direction, i.e. orthogonal to the longitudinal axis of the well 10.

More specifically, it can be considered that

Zi,A=zi,AdL and Zi,B=zi,B/dL, wherein:

- dL is the physical length of the infinitésimal section to which Zi,A and Zi,B refer respectively; and

- Zi,A and Zi,B are the spécifie impédances per unit of length of the pipe-plate assembly which dépend on the geometry and corresponding spécifie electric parameters (conductivity, dielectric constant) of said assembly.

The transmitting métal plate 21 of the first module -25--MCI InjecLs into the fluid surrounding the pipe string/

a variable	electric	current	modulated	by	the
information	signais	carrying	the data	to	be
transmitted.
The current flows	through	the fluid, through	the

casing, if present, and through the rock formation surrounding the well 10, subsequently returning to the ground reference of the transmitting métal plate 21

-, ²⁰ ο through the steel of the pipe for cableless bidirectional data transmission and continuous circulation 50 with which the plate is associated.

A part of this current reaches the receiving métal plate 22 of the second communication module MC2. This current is amplified and then acquired by the electronic processing and control unit to extract Phe information contained therein, or directly re-amplified to be re-transmitted to a third communication module.

In the electric diagram of figure 7, the electronic processing and control unit of the first communication module MCI, is represented by a voltage generator having an amplitude VTX, whereas the transmitting métal plate 21 is represented by the node PT. The voltage 15 generator having an amplitude VTX, is coupled, through the transmitting métal plate PT, with an overlying stretch of fluid; this coupling is modelled with the impédance ZT1. This stretch of fluid also has an impédance ZT2 which dérivés part of the current generated by the transmitting métal plate towards the ground - or rather towards the métal body of the pipe to which the transmitting métal plate 21 is applied.

The receiving métal plate of the second communication module MC2 is represented in the “75--electronic—diagram—of—figure—7—by—fcbe—node——^this receiving métal plate 22 is coupled with the overlying stretch of fluid; this coupling is modelled with the impédance ZR1. This stretch of fluid also has an impédance ZR2 which dérivés part of the current close 30 to the receiving métal plate towards the ground, or towards the métal body of the pipe to which the receiving métal plate 22 is applied. The receiving métal plate is in turn connected to the electronic processing and control unit of the second communication module schematized, in particular, as an amplifier with low input impédance current ZIN (approximately zéro) which in fact amplifies the current signal that crosses the receiving métal plate, obtaining a voltage signal VRX, containing the information^- received!

If the transmitting métal plates 21 and the receiving métal plates 22 hâve the form of a 10 cylindrical arc, the coupling efficiency of the same plates with the fluid surrounding the pipe string substantially dépends on the length of the longitudinal section of this arc and the angle described by the arc. The greater the length of the angle and the doser this 15 is to 360°, the greater the efficiency of the abovementioned coupling will be.

If the communication module 20 also comprises, in addition to the métal plates 21, 22, 35, transmitting and receiving coils, the cylindrical arc preferably 20 does not trace a complété angle of 360°, to avoid parasite currents induced on the métal plates 21, 22, 35 during the excitation of the coils.

With respect to the transmission of signais between two communication modules through the transmitting and -g-g--recel v Ing—uull s——2 G,—the—schemutio—viows—o-f—figures and 9 should be considered as being exemplary. In particular, the magnetic field Unes generated by a transmitting coil 25 and concatenated to a receiving coil 26, are represented in figure 9.

As can be observed, the arrangement of the coils in a configuration coaxial to the connecting pipes 50 of the pipe string 60 allows the magnetic field flow which is concatenated with the receiving coil 26, to be maximized. The receiving coil 26, in fact, substantially encloses the whole circumferential extension of the pipe for cableless bidirectional data 5 transmission and continuous circulation 50 made of ferromagnetic steel, in which most of the magnetic field flow is confined. The signal usefül—fo-r-tfre—heads of the receiving coil______ 26 thus contains the contributions of the whole magnetic field distribution generated by the transmitting coil 25 from the position of the receiving coil onwards.

The characteristics of the pipe f°^r cableless bidirectional data transmission and continuous circulation and the pipe string object of the présent invention are évident from the description, as also the relative advantages are clear.

The transmission towards the surface of the détections of the sensors located in the well takes place in a safe and inexpensive manner and 20 substantially in real time, allowing a continuous monitoring of the well-bottom parameters in real time, therefore allowing to increase the safety during drilling, in particular during the délicate steps of a change or addition of pipe in the pipe string, thanks -25---to the posSlblliLy of intcrvcning immédiate!y i.n the case of the détection of anomalies and déviations from the expected parameters.

In fact, through the data management and analysis in real time, the change in the formations crossed and 30 déviations in the trajectory of the well with respect to the program can be identified immediately, allowing operational decisions to be taken more rapidly and intervening with corrective actions.

The pipe string, according to the présent invention, moreover, also allows ail the well-bottom data to be provided during the well control phases, in which the Blow Out Preventer (BOP) is closed, or during ail the managed pressure drïTTing applications.

The data are transmitted in continuons also in the presence of circulation losses. There is no longer the 10 necessity of slowing down the operations for sending commands to the automatic well-bottom equipment to set or correct the drilling trajectory.

The capacity of transmitting large volumes of data, maintaining high drilling advance rates, allows log 15 while drilling measurements to be sent to the surface in real time with a higher définition than the current standard, and the possibility of permanently replacing existing wireline logs.

The possibility of having sensors along the whole drill string allows the continuous monitoring along the whole axis of the well of parameters such as pressure, température, voltage loads and compression, torsion, bending. This allows, for example, string grip events, washout identification, etc., to be prevented and -55---effectively solved.-----------------------------:------------The field of application mainly refers to the drilling step of an oil well but does not exclude use also during the production step. The pipe for cableless bidirectional data transmission and continuous circulation can in fact be integrated both within a drill string and a completion string and in any case in ail situations in which data can be transmitted or received from the well bottom or from intermediate points along the pipeline.

Intégration in a single object of the communication module and valves for continuons circulation also 5 allows a réduction in the installation times of these devices along the pipe string. In order to ensure the monitoring of the well conditions and continuons circulation in the case of a change or addition of a pipe, the installation of a single device, the pipe for 10 cableless bidirectional data transmission and continuous circulation, is in fact required.

The compact dimensions of this pipe for cableless bidirectional data transmission and continuous circulation also allow the maximum lengths for the pipe 15 strings provided on drilling machines currently existing, to be respected.

Finally, the pipe for cableless bidirectional data transmission and continuous circulation and the pipe string thus conceived can evidently undergo mimerons 20 modifications and variants, ail included in the invention; furthermore, ail the details can be substituted by technically équivalent éléments.. In practice, the materials used, as also the dimensions, can vary according to technical requirements.

Claims (4)

1) Pipe for cableless bidirectional data transmission and the continuous circulation (50) of a stabilizing fluid in a well for the extraction of formation fluids

5 comprising:

- a hollow tubular body (51) which extends in length âlông a longitudinal direction X and wHTcïf ïs“ configured at the ends for being coupled with respective drill or completion pipes (11);

10 - a radial valve (52) associated with said tubular body (51) arranged to control the flow of a fluid in a substantially radial or transversal direction with respect to the longitudinal direction X, said radial valve (52) being connectable to a pumping system (40)

15 of a drilling rig (10) outside said tubular body (51);

- an axial valve (53) associated with said tubular body (51) arranged to control the flow of a fluid along said longitudinal direction X;

- a communication module (20) associated with said

20 tubular body (51) comprising:

- at least one métal plate (21,22,35) selected from:

- a transmitting métal plate (21);

. - a receiving métal plate (22)

- a transceiver métal plate (35);

-2-5-------sm—electronic—processing—ëtftë—control—unit (23) configured for processing signais to be transmitted by means of said at least one métal plate (21, 35) or signais received by means of said at least one métal plate (22, 35);

30 - one or more supply batteries (24) for feeding said métal plates (21, 22, 35) and said electronic processing and control unit (23) .

2) Pipe for cableless bidirectional data transmission and the continuons circulation (50) of a stabilizing fluid in a well for the extraction of formation fluids according to claim 1, wherein said communication module

5 (20) comprises at least one transmitting coil (25) and at least one receiving coil (26) coaxial with respect to each other and coaxial with “respect tô the “ longitudinal axis of said tubular body (51) .

3) Pipe for cableless bidirectional data transmission

10 and the continuons circulation (50) of a stabilizing fluid in a well for the extraction of formation fluids according to claim 2, wherein said at least one transmitting coil (25) and said at least one receiving coil (26) are superimposed with respect to each other.

15 4) Pipe for cableless bidirectional data transmission and the continuons circulation (50) of a stabilizing fluid in a well for the extraction of formation fluids according to any of the previous daims, wherein said supply batteries (24) and said electronic processing

20 and control unit (23) are housed in a first housing (54) of said tubular body (51) , whereas said at least one métal plate (21, 22, 35) and said coils (25, 26) are housed in a second housing (55) of said tubular body (51).

-d--dj---Pipe—for—cableless bidirectional data transmission and the continuous circulation (50) of a stabilizing fluid in a well for the extraction of formation fluids according to claim 4, wherein said first housing (54) and said second housing (55) are made in a longitudinal 30 direction below said radial valve (52).

6) Pipe for cableless bidirectional data transmission and the continuous circulation (50) of a stabilizing fluid in a well for the extraction of formation fluids according to claim 4, wherein said first housing (54) is made at said radial valve (52) whereas said second housing (55) is made at said axial valve (53).

5 7) Pipe string (60) for a drilling rig of a generic well for the extraction of formation fluids comprising a plurality of pipes (11, 50) connected to each other in succession.said plurality of pipes(11. 50) comprising a plurality of drill or completion pipes 10 (11) and a plurality of pipes for cableless bidirectional data transmission and continuons circulation (50) according to any of the previous claims having a length shorter than that of said drill or completion pipes (11).

15 8) Pipe string (60) according to claim 7, wherein said pipes for cableless bidirectional data transmission and continuous circulation (50) are positioned between two drill or completion pipes (11) at predetermined intervals of one or more drill or completion pipes 20 (11) .