Tubular drill pipe, for e.g. oil field, has signal transmitting unit including flat electrical conductor insulated from internal surface of wall of pipe, where surface covers resin forming insulating coating

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The present invention relates to a drill rod capable of constituting a signal transmission medium along its length and through its coupling means to the rods which precede and follow it in a string of drill rods.

BACKGROUND OF THE INVENTION

There are many methods dealing with the transmission of information between a transmitter and a receiver in the field of drilling, in particular oil. The transmitter can be either the downhole equipment, the receiver then being the ground installation making it possible to record the parameters recorded at this bottom, or the transmitter can be the ground equipment to control the background equipment.

Controlling a drilling operation in real time requires an increasingly high signal transmission rate. To achieve the required requirements, we have been moving for several years towards technologies in which we try to control the quality of the supports of this signal propagation both in terms of its conductivity and in terms of its continuity. The support is of course made in the form of a loop forming a sort of signal circulation BUS. One of the branches of the loop is formed by the drill string itself and both in terms of conductivity and in terms of continuity, this drill string correctly meets the requirements for high speed transmission. The same is not true for the other branch of the loop which is electrically isolated from the drill string but whose conductivity and continuity are much more difficult to achieve.

Solutions to this problem are illustrated by documents FR 2 817 588, US 4 899 924, EP 295 178 ...

Particular mention will be made of document WO

0206716 and the document FR 2 819 751 which proposes for one an inductive solution and for the other a conductive solution to the establishment of a continuity of this second branch of the current loop at the level of each of the connections of the rods of 'a drill string.

OBJECT OF THE INVENTION

The present invention is an alternative solution to this problem of continuity and conductivity by which it is intended to reduce as much as possible the losses or attenuations of the signals at the level of each of the rod connections.

BRIEF DESCRIPTION OF THE INVENTION

To this end therefore, the invention relates to a tubular drilling rod made of electrically conductive material, comprising male connection means at one end and female at the other end and comprising signal transmission means, in which these rods signal transmission means comprise at least one electrical conductor in the form of a flat ribbon attached by adhesive bonding along the internal surface of the wall of the rod, electrically insulated from this surface which is then covered with the conductor with an insulating synthetic coating resistant to abrasion and at least one annular antenna at each end of the rod.

The first advantage of this tubular drill rod structure resides in the fact that it does not differ in manufacturing from an absolutely conventional rod. Its additional equipment can be achieved in an extremely simple manner as regards the running part of this rod. Furthermore, this additional equipment does not introduce any significant roughness into the interior space of the drill string which could be subjected to increased abrasion due to the disturbance introduced into the flow of the slurry.

Preferably, the conductive tape is provided with through perforations so that the insulating and abrasion resistant coating can fill these perforations and improve the attachment of the flat tape to the rod.

To achieve the continuity of this attached conductor at each of the rod connections, the invention proposes several different structures.

First of all, in a first embodiment, the flat strip is connected at each of its ends to at least one insulated annular conductor with an axis parallel to the axis of the rod and housed in a recess of the connection means. In conventional drill rods, the connection means are generally screwing means with conical threads produced respectively on a nose which is partly male and inside a sleeve which is partly female. There are therefore places of the sleeve and places of the nose which will meet face to face when the connection is made and it is in these places that the aforementioned recesses will have been made so that these recesses are opposite the one from the other at the end of the abutment of two rods. One of the advantages of this structure is that the annular conductors located in the recesses are protected from the aggressive medium which may constitute the mud circulating inside the rod. They are coupled by radiation in the manner of antennas and provision can advantageously be made for each annular conductor to be produced in the form of a winding of several adjacent turns. And since the coupled annular conductors are housed one inside the other, the quality of the transmission at the level of the rod seal is independent of the precision of the production of the connection means.

To improve transmission by radiation, the walls of each of the recesses are coated with a non-magnetic material to form a Faraday cage.

In a variant of this first embodiment, each annular conductor is embedded in a ring of synthetic material which is electrically insulating with respect to the faces of the recess. In order to optimize the coupling by radiation, it is also possible to provide according to the invention that each annular (electrically insulated) conductor, ring or succession of turns, either embedded in a synthetic material which is either conductive or comprises an insulating part. facing the faces of the recess and a conductive part in contact with the annular conductor and facing the recess of the other rod when two consecutive rods abut.

Other characteristics and advantages of the invention will emerge from the description given below of some exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will be made to the accompanying drawings, among which:

<td></td><td>- Figure 1 is a view</td><td>schematic of a well</td>

<td>of</td><td>drilling in progress,</td><td></td>

<td></td><td>- Figure 2 is a view</td><td>outside of a rod</td>

<td>of</td><td>drilling,</td><td></td>

<td></td><td>- Figure 3 is a view</td><td>partial isometric</td>

<td>of</td><td>the stem from a plane of</td><td>cross section III-</td>

III of figure 2,

- Figure 4 illustrates a first embodiment of the invention,

- Figure 5 is a schematic view of a variant of this first embodiment,

- Figure 6 illustrates by the same view a second variant embodiment of Figure 4,

- Figure 7 is a diagram of a third variant embodiment of Figure 4,

- Figure 8 is a partial sectional view illustrating another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The diagram of FIG. 1 therefore represents a wellbore in progress. The drill string 1, consisting of a series of drill rods such as 1a, 1b is rotated by the table 2 of the installation or derrick 3 resting on the ground. The entire drill string is supported by a block 4 which allows the translations of the drill string and the application of weight on the drilling tool 5. The latter is generally fixed to the lower end of a drill collar 6 in which is housed an electronic module 7 which includes both the sensors and the means for transmitting information to the surface or receiving other information from. from the surface. The clean drilling mud is injected by means of a pump at the level of the adduction head 8, passes through the whole of the drill string to come out at the level of the drilling tool. The loaded mud then circulates in the annular space 9 between the outer surface of the drill string and the walls of the borehole 10. At the high end of the borehole, a tube 11 is sealed in the ground 12 by means of a cement grout 13. The tube is itself surmounted by an isolation valve 14 through which the drill string passes as well as the return of the loaded sludge extracted by the weir 15.

A surface electronic device 16 is connected to the drill string 1 by means of a cable 17 and a rotating collector 18 located on the first rod 19. The electronic means 16 can equally well include a recording unit. as actuator control devices to modify the trajectory of the drilling, for example. As the drilling deepens, the drill string is opened and an additional rod is inserted between the first rod 19 and the rest of the drill string.

Each of the rods used is shown in Figure 2 in its vertical orientation suitable for its insertion into the drill string. Thus, in a known manner, each rod has an upper female sleeve 20 fitted internally with a conical thread 21 which extends between two bearing shoulders 22 and 23. In the lower part, the rod has a nose of connection 24 with an external conical thread 25 which extends between two shoulders 26 and 27. When a rod is butted against the drill string, its shoulder 26 is in contact with the shoulder 22 of the last rod of the drill string. It is also possible that the shoulder 27 is in contact with the shoulder 23 of the latter rod, but this is not always the case.

In Figure 3, there is a hollow rod 1a, 1b tubular sectioned in its main part and internally equipped with a flat conductor 28 bonded to the internal surface of the rod by means of an insulating adhesive 29 and covered as well as all the remainder of the inner surface of the shank of a resin forming an insulating and abrasion resistant coating. This figure shows an orifice 31 opening through the flat conductor 28 and the insulating adhesive 29, this orifice having the advantage of being able to be filled by the synthetic material 30 and therefore of strengthening the connection of the conductor 28 to the rod. drilling. The conductive tape 28 naturally has several. In addition, a rod can include several conductive tapes. The internal surface of the drill string is very little disturbed by these glued and coated tapes so that this addition is not very subject to intense erosion by the mud in circulation.

In Figure 4 there is shown, by a partial axial section, the connection of two successive drill rods. We find in this figure some of the elements already described with the same references. It can be seen that the threads 21 and 25 are framed both as regards the male part and the female part of the rod connecting elements by cylindrical sections 32, 33 for the male part and 34, 35 for the female part. When the assembly is carried out, the cylindrical section 35 of the female part is located opposite the cylindrical section 33 of the male part, each of these sections being provided with a recess 36 in the female part and 37 in the male part. . In each of these recesses, there is disposed a circular conductor here shown in the form of several electrically insulated turns referenced 38 for the female part and 39 for the male part, electrically connected to the plane conductor 28 bonded to the inner surface of each of the rods. connected. The axis of these windings is that of the rod. The connection of the windings 38 and 39 to the conductive tape 28 is made by an insulated wire 40 housed in a notch 41 formed in the shoulder 23 of the female part and by an insulated wire 42 housed in a radial hole 43 formed in the male nose 24 substantially at the junction of the cylindrical section 33 and the threaded section 25.

Preferably, each recess 36 and 37 is coated with a non-magnetic sheet material 44, 45 (copper, nickel, etc.) forming a Faraday cage for the two windings 38 and 39 which are thus electromagnetically coupled to each other. the way of an antenna. The turns of insulated wire as well as the insulated wires for connecting these turns with the tape 28 are embedded in an electrically insulating resin matrix which is resistant to the pressure of the drilling mud. The quality of the coupling is dependent on the accuracy of the relative axial position of the windings 38, 39 therefore on the accuracy of the dimensions separating the shoulders 22, 23 and 26, 27 of each rod.

In Figure 5, there is shown an alternative embodiment of this arrangement for coupling the conductive tapes 28 to each other at each rod junction, in which recesses 46 and 47 have been made in the cylindrical sections 32 and 34 described above. . These recesses also accommodate a winding of insulated conductor wires 48, 49 electrically connected to the conductor 28 corresponding to the rod in which the recess has been made by means of suitable passages (grooving and bores).

In Figure 6 we find some of the elements already described with reference to Figure 4 with the same references. In this particular case, the insulated turns of the windings 38 and 39 are embedded in a rubber or an elastomeric material 50, 51 made conductive by a conductive filler (carbon powder, etc.). The thickness of this coating 50, 51 is such that when the rods are butted together by screwing, a slight interference occurs between these coatings at their contact, which ensures continuity between these two elastomers which becomes an almost continuous medium. propagation of radiation.

In FIG. 7 the embodiment variant shown differs from the previous ones in that the windings are replaced by flexible copper rings 52, 53 formed from braids. Each of these bands is coated in an elastomer with two materials 54, 55, the elastomer 54 being insulating and turned towards the recesses while the elastomer 55 which coats a ring is a conductive elastomer which faces the conductive elastomer. that wraps around the other ring. Each of the rings may have inking extensions 56 in the conductive elastomer formed, for example, by punctures or depressions made by press in the braid of their production. As in the case of FIG. 6, the hardness of the elastomer is a hardness which corresponds to that of the O-rings for example. In the same way as for FIG. 6, the dimensions of the coatings are such that when the rods are connected, there is a slight pressure between the conductive elastomers 55 which therefore ensure a virtual physical continuity between the rings 52 and 53.

The fixing of these circular conductors in the corresponding recesses is carried out by any means and in particular by gluing. It will also be noted that in FIGS. 6 and 7 the recess produced on the male coupling part opens out at the end of this part. We can take advantage of this arrangement to axially lengthen the coating of the copper ring 53 in order to cause axial compression of this coating during the connection of the rods, axial compression which would lead to a radial swelling of this coating and therefore to a better contact between the conductive parts of the coating.

Finally, FIG. 8 shows another embodiment of the invention in which the flat strip is connected at each of its ends to an annular conductor, for example a copper ring 57, 58 respectively housed in a recess 59 , 60 provided at each end of the inner surface of the rod. This copper ring is insulated from the rod by a sleeve 61, 62 made of an insulating material, for example a plastic material such as polyethylene, and a conductive seal 63 formed by a crush ring is placed between the two front surfaces of the copper rings 57 and 58 facing each other so that it can be pinched and crushed between cel2881172 ίο these when connecting. This crushing ensures electrical continuity between the rings of each rod. The seal 63 may advantageously be provided with lips 64, 65 which cover the ends of the copper rings themselves coated with the aforesaid coating 30. The crush seal makes it possible to take into account the dimensional dispersions of the threaded assembly of the rods due to manufacturing tolerances (or makes it possible to maintain wide manufacturing tolerances). The transmission is carried out, in this case also, mainly by radiation between the two rings 57 and 58, in particular through the seal 63 which constitutes a privileged guide of this radiation (like the conductive elastomers described above).