The invention relates to the field of electromagnetic coupling applied to the field of exploration and working oil or gas fields in which mutually communicating drill strings are used, constituted by tubular components such as standard drill pipes, which may be heavy weight, and other tubular elements, in particular drill collars in the bottom hole assembly, connected together end-to-end as required by the drilling process
Drilling for oil and the pipeline field are fields in which the transmission of information has become a determining element.
However, certain cutting edge industrial fields such as drilling for oil have operational environments that render data transmission difficult.
As an example, in the context of drilling for oil, measurement means are disposed at the deepest tubes of the drill string. Such measurement devices are used to pick up data pertaining to the drilling environment, especially with a view to directing the drilling.
Bringing that data to the surface is a major problem because the operating environment for such tubes is hostile and renders the use of conventional telecommunication means impossible.
The operational environment in fact poses many problems as regards the supply of the various elements. Furthermore, that environment is also the source of numerous interferences which perturb the signal along the tube string.
Two principal technologies have been developed in response.
The first of those technologies consists of sending the data through the mud moving in the string via sound waves. That method has proved to be highly insufficient in terms of rate, as it can only offer rates of the order of one to a few bits per second.
The second technology, which is still being developed, uses cabled tubular connections coupled to techniques for coupling by magnetic induction. Thus, a coupling element is disposed at each end of each tube, and a wire connects the coupling elements of each tube. It is then possible to transmit the signal from tube to tube along the string, the coupling elements at the end of two successive tubes ensuring transmission between those two tubes.
That technology can be used to increase the rates to a few kilobits per second. However, that increase in rate is at the expense of limited reliability. Further, the losses at each pair of coupling elements of consecutive tubes are high, which means that a lot of supply repeaters have to be included in the string in order to amplify the signal level. Such repeaters are expensive, difficult to maintain and are difficult to incorporate into the design of the drill stem.
In the pipeline field, the operating environment is also very aggressive, and of little use to wireless communications. Thus, it is still necessary to provide cabled connections.
In order to connect two cabled portions of a unit, a coupler then becomes necessary. However, couplers with contacts suffer from many disadvantages in an aggressive environment. In response to this problem, contactless couplers have been developed. However, such couplers cannot be used to obtain good performances in transmission.
In the prior art, the documents GB-2445207, US-2004-0094303, U.S. Pat. No. 6,392,317 and US-2010-0052941 disclose various solutions for coupling drill strings together.
Currently, no coupler, with or without contact, is satisfactory for the transmission of information over long distances in a hostile environment.
The aim of the invention is to improve this situation.
To this end, the invention proposes an electromagnetic coupler comprising a first coupling element for mounting on a first support element and a second coupling element for mounting on a second support element. The first coupling element comprises a first annular body formed at least in part from a high magnetic permeability material which houses a first conductive winding and which has an open transverse section, and the second coupling element comprises a second annular body formed at least in part from a high magnetic permeability material which houses a second conductive winding and which has an open transverse section.
The first body and the second body have complementary shapes such that when two support elements respectively receiving the first coupling element and the second coupling element are coupled, the first body and the second body form a structure enclosing the first conductive winding and the second conductive winding. The first conductive winding and the second conductive winding are respectively positioned in the first body and in the second body such that the respective surfaces of the first conductive winding and the second conductive winding are substantially parallel when two support elements respectively receiving the first coupling element and the second coupling element are coupled.
More particularly, the invention proposes an assembly of at least two tubular drill string components for drilling a hole with movement of a drilling fluid, comprising:
the first coupling element comprising a first annular body formed at least in part from a high magnetic permeability material which houses a first conductive winding and which has an open transverse section;
the second coupling element comprising a second annular body formed at least in part from a high magnetic permeability material which houses a second conductive winding and which has an open transverse section;
the first body and the second body having complementary shapes such that when two support elements respectively receiving the first coupling element and the second coupling element are coupled, the first body and the second body form a structure enclosing the first conductive winding and the second conductive winding;
characterized in that the first conductive winding and the second conductive winding are respectively positioned in the first body and in the second body such that the respective surfaces of the first conductive winding and the second conductive winding are substantially parallel when two support elements respectively receiving the first coupling element and the second coupling element are coupled.
Advantageously, the first conductive winding has a substantially flat or cylindrical surface facing the opening of the transverse section of the first body, the second conductive winding may have a substantially flat or cylindrical surface facing the opening of the transverse section of the second body, and in which these surfaces then form the respective surfaces of the substantially parallel first conductive winding and the second conductive winding when two support elements respectively receiving the first coupling element and the second coupling element are coupled.
In other words, the first conductive winding and the second winding may be flat and disposed parallel to each other when the first tubular component is coupled to the second tubular component. Alternatively, the first conductive winding and the second conductive winding may have a substantially cylindrical surface such that the windings are disposed concentrically with respect to each other when the first tubular component is coupled to the second tubular component.
As an example, the transverse section of at least one of the first body and the second body may have a general shape selected from the group comprising a square bracket, a “U”, an “L”, a “J”, an “E” or a “V”.
In particular, the first body and the second body have respective end chamfers and in which the chamfers of the first body are substantially facing at least certain of the chamfers of the second body when two support elements respectively receiving the first coupling element and the second coupling element are coupled.
Advantageously, the surfaces of the first body and the second body may face each other when two support elements respectively receiving the first coupling element and the second coupling element are coupled are at a distance from each other which is in the range 100 μm to 500 μm.
As an example, the first conductive winding and the second conductive winding may comprise a conductor selected from the group comprising a copper winding, a copper winding coated with an insulating coating, a printed circuit, and a printed circuit coated with an insulating coating.
Depending on the embodiment, the first conductive winding and the second conductive winding may comprise in the range one to ten turns in cross section.
As an example, the strips or turns of the first conductive winding are substantially aligned, superimposed, with the strips or turns of the second conductive winding when two support elements respectively receiving the first coupling element and the second coupling element are coupled.
In particular, a winding, preferably both windings, may comprise two turns with reverse orientations disposed on a body comprising at least one arm between said two turns.
Preferably, in the coupled state, the first conductive winding and the second conductive winding may be disposed at a distance in the range 0.5 mm to 5 mm with respect to each other.
As an example, at least one of the first body and the second body is coated with an element, component or coating comprising a ceramic comprising ZrO2 or Al2O3 or Cr2O3.
As an example, at least one of the first body and the second body comprises a plurality of ring segments formed from a high magnetic permeability material received in an annular support.
In particular, the annular support may comprise a material selected from the group comprising silicone, a hydrogenated nitrile rubber, a fluoroelastomer, a perfluoroelastomer or an ethylene-propylene-diene monomer or from the group comprising titanium, amagnetic stainless steel and zirconium.
More particularly, the high magnetic permeability material may have a relative magnetic permeability of more than 100 in the 1 kHz to 10 MHz band. It may be formed from a ceramic comprising MnZn; for example, it may be a soft ferrite.
The electromagnetic coupler proposed is particularly advantageous as it means that low loss signal transmission can be achieved over a very broad frequency band of one or more MHz, since the area of the facing surfaces is high.
This means that rates of several hundred kilobits per second to several megabits per second can be obtained, while limiting the need for repeaters.
Other characteristics and advantages of the invention will become clearer from the following description of examples given by way of non-limiting illustration, with reference to the drawings in which:
The following drawings and description essentially contain distinct elements. Thus, they not only serve to provide a better understanding of the present invention but also, if necessary, contribute to its definition.
As can be seen in
Conventionally, the first end 103 is a female end and the second end 104 is a male end. As can be seen in
In order to form a communicating drill string assembly of the invention, when a first end 103 of a first tubular component 101 is made up onto the second end such as 104 of the second tubular component 110, then a first coupling element 6 at the first end is coupled to a second coupling element 8 at the second end, so as to ensure continuity of the communications line from one tubular component to another.
The device comprises a first support element 2, a second support element 4, the first coupling element 6 and the second coupling element 8. The respective first support element 2 and the second support element 4 are each respectively retained in a housing formed in a tubular component and opening parallel to or laterally to the longitudinal axis X.
The first coupling element 6 is mounted on the first support element 2 and is maintained by means which are not shown. These means may vary, such as fixing means, screw means, nesting means, interference fit means or any other appropriate means. In the same manner, the second coupling element 8 is mounted on the second support element 4 and is maintained by means which are not shown. Said means may be identical to those supporting the first coupling element 6 on the first support element 2, or they may be different.
The first support element 2 and the second support element 4 are disposed with respect to each other such that the first coupling element 6 faces the second coupling element 8.
In this configuration, the first coupling element 6 and the second coupling element 8 have substantially parallel faces, and together define an electromagnetic coupler 10.
The principal role of the first support element 2 and the second support element 4 is to position the first coupling element 6 and the second coupling element 8 with respect to each other in order to optimize the efficiency of the electromagnetic coupler 10. The first tubular component 101 retaining the first support element 2 presents the latter facing the second support element 4 retained on the complementary second tubular component 110 when the connection between these tubular components is made. The tubular components are intended to be connected by makeup.
Preferably, these tubular components comprise at each end an external abutment “Be” and an internal abutment “Bi”, the support elements preferably being carried so that they can be coupled at the internal abutments. In the made up state, the internal abutment of the first tubular component is in contact with the internal abutment of the second tubular component. Similarly in this made up state, the external abutment of the first tubular component is in contact with the external abutment of the second tubular component. In a particular embodiment, shown diagrammatically in
As can be seen in this Figure, the coupling element 6 comprises an annular body 12. In the example, this longitudinal axis X is superimposed on the axis of revolution Y of the annular body 12. The annular body 12 has a cross section with an arm 14 and an arm 16 which are connected and together form an L. The arm 14 is arranged such that it is substantially parallel to the axis of the body 12, in particular parallel to the axis of revolution Y of the annular body 12. The arm 16 is orthogonal to the axis of revolution Y. The opposed ends of the arms 14 and 16 define an opening 18. The arms 14 and 16 also define annular surfaces, as can be seen in the perspective view of
The first coupling element 6 also comprises a conductive winding 20. In the example described here, in
The coupling element 8 is similar to the coupling element 6, and has an annular body 22 with an arm 24 and an arm 26 which are connected and together form an L. The arm 24 is arranged so that it is substantially parallel to the axis of the body 22, in particular parallel to the axis of revolution of the annular body 22. The opposed ends of the arms 24 and 26 define an opening 28. In similar manner to the coupling element 6, the arms 24 and 26 also define mutually orthogonal annular surfaces.
The second coupling element 8 also comprises a conductive winding 30. In the example described here,
In the example described in
In this embodiment of
In a variation, in the example of
In the example described here, the windings 20 and 30 are produced from a copper conductor covered with an insulating layer. In a variation, these windings could be formed from a material other than copper by means of a printed circuit. In a variation, the windings 20 and 30 are formed by conductive tracks printed into the surface of a substrate, the substrate being formed from epoxy, for example, or from ceramic, or formed from Kapton®, said tracks possibly being wound into turns with no contact between the turns. The substrate is selected to perform well mechanically under pressure and neither break nor crack under such loads.
In the representations of
Alternatively, in the embodiment of
Advantageously, said windings 20 and 30 may be produced by means of any conductor with a shape such that one of its surfaces is very large with respect to its thickness. In the embodiment described here, this ratio is 4 or more.
When the windings 20 and 30 are cylindrical, this thickness “e” is measured radially relative to the axis of revolution of the cylinder, and have a width “l” corresponding to the height of one turn along this axis of revolution of the cylinder. In this configuration, the width to thickness ratio is 4 or more.
When the windings 20 and 30 are flat, this thickness “e” is method along the axis of the winding, in a sectional plane passing through its winding axis, and its width “l” is measured radially perpendicular to the axis of the winding. In this configuration, the width to thickness ratio is 4 or more.
Preferably, the windings 20 and 30 comprise at least two turns such that the section of said winding in a sectional plane passing through its winding axis comprises at least four turn sections.
Furthermore, the windings 20 and 30 may be disposed on their respective arm by depositing a printed circuit or by any other appropriate fixing means, such as an interference fit, a groove in the arm or something else.
In the example described here, the body 12 and the body 22 are produced from a ceramic comprising MnZn. This material is also known as “soft ferrite” and its generic formula is MnaZn(1−a)Fe2O4. This material has a relative magnetic permeability μr of several hundred in the range 500 kHz to 2 MHz. Further, this ceramic has a very high electrical resistance. In a variation, the body 12 and the body 22 could be formed from another type of ferrite, or from another solid material with a relative magnetic permeability of more than 100 in the 1 kHz to 10 MHz band, and with a negligible or zero electrical conductivity.
The principal difference between the coupling elements 6 and 8 resides in that the transverse section of the coupling element 6 is substantially symmetrical with the transverse section of the coupling element 8 with respect to a straight line which passes through the opposed ends of the arms 14 and 16. Thus, when the first support element 2 and the second support element 4 are engaged, the bodies 12 and 22 face each other, as do the conductive windings 20 and 30. In this position, the bodies 12 and 22 surround the windings 20 and 30.
As can be seen in this figure, the body 12 and the body 22 make up to produce a substantially rectangular contour in section which surrounds the windings 20 and 30 and defines a space 31. Thus, the shapes of the bodies 12 and 22 are termed “complementary”.
In the assembled position of the support elements 2 and 4, the bodies 12 and 22 define a structure that encloses the conductive windings 20 and 30. When being assembled, the bodies 12 and 22 are brought into mutual proximity and define an almost closed chamber respectively bordered by the arms 14, 16, 26 and 24, corresponding to this space 31. This chamber is annular. This chamber is not necessarily arranged in a sealed manner.
In this embodiment, the arms 14, 16, 24 and 26 each have a respective chamfer 32, 34, 36 and 38. The chamfers 32, 34, 36 and 38 are produced such that the chamfers 32 and 38 and respectively 34 and 36 substantially face each other when the first support element 2 and the second support element 4 come into engagement. The chamfers 32, 34, 36 and 38 form tapered surfaces.
The arms 14 and 26 and respectively 16 and 24 do not come into contact with each other, and so a space 39 and respectively a space 40 separate these arms at the chamfers 32 and 38 and respectively 34 and 36. The role of the spaces 39 and 40 will be explained below.
In the example described here, the arm 14 and the arm 24 have a length of 9.3 mm, and a width of 1.6 mm. In this same example, the arm 16 and the arm 26 have a length of 5.6 mm and a width of 1.6 mm. The chamfers 32, 34, 36 and 38 are produced with an angle of 45° from a point located at a distance of 0.6 mm from the outermost edge of the end surface of each arm 14, 16, 24 and 26.
As can be seen in
The strips 42 to 45 and respectively 46 to 49 are spaced from each other by 450 μm. As mentioned above, the bodies 12 and 22 have shapes such that the windings 20 and 30 are substantially parallel. In particular, as can be seen in
As illustrated in
In fact, the electromagnetic coupler 10 can advantageously be produced in a more accurate manner. In this case, not only are the windings 20 and 30 parallel but, as can be seen in
Thus, the strip 42 is parallel to and facing the strip 46, the strip 43 is parallel to and facing the strip 47, the strip 44 is parallel to and facing the strip 48, and the strip 45 is parallel to and facing the strip 49.
In the assembled position of the support elements 2 and 4, when the windings 20 and 30 are flat, they are disposed such that their respective axial projection along a winding axis Y onto a plane perpendicular to this winding axis are superimposed by more than 90%, or even by more than 97%, as can be seen in
When the windings 20 and 30 are concentric, the radial projection of the internal winding onto the external winding produces a degree of superimposition of the windings of the order of 90%, or even more than 97% because of the geometry selected for these windings, as can be seen in
Such a geometry in the invention guarantees a reproducible degree of superimposition of the projections of the turns without necessitating angular indexation of the winding in its support element, nor even an angular indexation of said support element on the tubular component. Manufacture of the assembly of the invention is thus facilitated, while preserving the quality of signal transmission by optimizing and controlling the capacitive effect over the entire length of the drill string, and indeed at each of the connections between two tubular components.
In the example described here, the strips of the winding 20 and the strips of the winding 30 are separated by a distance D of 2.6 mm. When the windings 20 and 30 are cylindrical, the distance D is measured radially relative to the winding axis Y. When the windings 20 and 30 are flat, the distance D is measured along the winding axis Y.
In fact, in order to protect the windings 20 and 30 against a liquid or another element which could be introduced via the spaces 39 and 40 into the space 31, each winding 20 and 30 is covered with a layer of material 51, preferably comprising 1 mm thick Al2O3. This material 51 may be an adhesive that can also fix the winding in its respective annular body 12 or 22. In other embodiments, this layer may be omitted.
The winding 20 (respectively 30) illustrated in
The winding illustrated in
Preferably, the windings 20 and 30 have an identical number of turns.
The magnetic coupler proposed here uses a physical phenomenon the effects of which were a surprise to the Applicant. The particular disposition of the windings and their confinement in the space defined by the ferrite body result in a non-linear combination of a capacitive effect and an inductive effect which results in excellent transmission performance.
Thus,
Experiments have shown that when the frequency of the current approaches 400 kHz, the phase of the magnetic field reverses.
Finally, as can be seen in
Because of the performances of this coupler, it is possible to transmit data via GMSK (Gaussian Minimum Shift Keying) modulation over wide 100 kHz frequency bands in the 100 kHz-2 MHz band. Other types of modulation could be used, in particular any type of frequency modulation.
It is advantageous to avoid the 350 kHz-450 kHz band because of the magnetic field phase inversion. Studies by the Applicant have shown that by optimizing the parameters, it is reasonably easy to obtain a working transmission band in the range 8 MHz to 10 MHz.
Physically, it would appear that the particular magnetic field of the electromagnetic coupler 10 “shields” the capacitances formed by the windings, thus improving the transmission gain.
Experiments by the Applicant have demonstrated that the performance of the electromagnetic coupler 10 depends on several parameters.
One parameter is the number of turns in each winding. The greater the number of turns, the lower the frequency above which the gain is satisfactory.
Another parameter is the alignment of the turns between themselves. It is important that the turns are properly aligned facing each other in order to avoid loss of energy. Currently, the Applicant assumes that these “non-alignment” losses are due to losses of capacitive transfer.
Another parameter is the spacing between the turns. In fact, the closer they are, the higher is the risk of an unwanted inter-turn capacitive effect. However, because of the very “flat” shape of the strips of the windings, the Applicant has discovered that maximizing the “conductive space” available on each body is of advantage in order to increase the capacitive transfer. Conductors which are generally not flat but have a flat surface may be used, but the best results are currently obtained with flat conductors.
Another parameter is the spacing between the chamfers 32, 34, 36 and 38 of the bodies 12 and 22. The best yields are obtained when the respective chamfers of the bodies are in contact with each other. This means that a maximum magnetic permeability can be obtained, which leads to optimized transmission. In contrast, this causes problems as regards reproducibility on an industrial scale. The graph of magnetic permeability as a function of the distance between the chamfers of the bodies varies greatly between 0 and 100 μm. However, this distance generally results from engaging the reception elements which receive the coupling elements. And if several magnetic couplers 10 are in series, and they have different magnetic permeabilities, a phenomenon of impedance mismatch occurs which results in almost total loss of signal. Consequently, the Applicant has determined that in applications in which several magnetic couplers are in series, the spacing should advantageously be in the range 100 μm to 500 μm, with a controlled distance range for mounting the support elements together, and in which the magnetic permeability varies only slightly.
Another parameter is the shape of the bodies 12 and 22. The bodies 12 and 22 in the example described above have an “L” section where one of the arms is very small with respect to the other. However, numerous other shapes are possible. Thus, studies by the Applicant have shown that a square bracket or “[” section shown in
In particular, the embodiment of
Another parameter is the use of a coating for the bodies 12 and 22. Studies by the Applicant regarding the use of an electromagnetic coupler 10 in the oil drilling field have shown that is advantageous to coat the bodies with a ceramic preferably comprising ZrO2 or, in a variation, with Al2O3. These coatings are more resistive than the material of the bodies, which can improve the transmission gain. It is also possible to use Cr2O3. Other coatings or added parts could be used. The added-on part may be massive, for example cut from a single piece.
Another parameter is the composition of the annular bodies. These do not have to be produced entirely from ferrite. It is possible to form the ring segments from ferrite and to dispose them on an annular support, for example an elastomer such as silicone, a HNBR (hydrogenated nitrile rubber), a FKM (fluoroelastomer), a FFKM (perfluoroelastomer), or an EPDM (ethylene-propylene-diene monomer). The windings are housed in an identical manner. This renders the manufacture of the bodies 12 and 22 easier and the elastomer means that the body 12 and 22 is better able to tolerate environmental stresses. In one embodiment, the annular support may be rigid compared with the above. The annular support may include titanium and/or amagnetic stainless steel, and/or zirconia.
The above described list of parameters is not exhaustive.
The Applicant has thus described an electromagnetic coupler comprising a first coupling element for mounting on a first support element and a second coupling element for mounting on a second support element. The first coupling element comprises a first annular body formed at least in part from a high magnetic permeability material which houses a first conductive winding and which has an open transverse section, and the second coupling element comprises a second annular body formed at least in part from a high magnetic permeability material which houses a second conductive winding and which has an open transverse section.
The first body and the second body have complementary shapes such that when two support elements respectively receiving the first coupling element and the second coupling element are coupled, the first body and the second body form a structure encircling the first conductive winding and the second conductive winding. The first conductive winding and the second conductive winding are respectively positioned in the first body and in the second body such that the respective surfaces of the first conductive winding and the second conductive winding are substantially parallel when two support elements respectively receiving the first coupling element and the second coupling element are coupled.
The Applicant has also described an electromagnetic coupler comprising first and second coupling elements each capable of being disposed at the end of a support element and comprising an annular body formed from a high magnetic permeability material, said bodies having complementary shapes, such that the first and second coupling elements can be coupled to form a magnetic circuit, said first and second coupling elements comprising respective windings defining between them a capacity of more than 2 pF when the first and second coupling elements are coupled.
The Applicant has also described an electromagnetic coupler comprising first and second coupling elements each capable of being disposed at the end of a support element and comprising at least one substantially flat electrode, the first and second coupling elements being capable of being coupled to form a capacitance, said first and second coupling elements further each comprising a respective annular body formed from a high magnetic permeability material, said bodies having complementary shapes and being arranged such that they form a magnetic circuit confining the capacitance when the first and second coupling elements are coupled.
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PCT/EP2012/053004 | 2/22/2012 | WO | 00 | 11/1/2013 |
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WO2012/113825 | 8/30/2012 | WO | A |
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