Information Transfer System

Abstract

A wireless downhole information transfer system is presented, which is adapted to operate in wells (well bores), and in particular in wells for the Oil & Natural Gas and Geothermal Industry. The information transfer system comprises an elongated tubing (completion) having several tubing sections comprising a first and a last end tubing section, an information signal generator placed at or near the first tubing section of the elongated tubing. The information signal generator is designed as a torsional wave generator for transmission of a torsional wave information signal along the elongated tubing, and an information signal receiver arranged at or near the last tubing section of the elongated tubing, wherein the elongated tubing between the signal generator and the signal receiver constitutes the carrier for transmission of the information signal between the signal generator and the signal receiver.

Claims

1. A wireless downhole information transfer system, comprising: an elongated tubing having several tubing sections, comprising a first and a last end tubing section, an information signal generator arranged at or near the first end tubing section of the elongated tubing and designed as a torsional wave generator for transmission of a torsional wave information signal along the elongated tubing, an information signal receiver arranged at or near the end tubing section of the elongated tubing, wherein the elongated tubing between the signal generator and the signal receiver constitutes the carrier for transmission of the information signal between the signal generator and the signal receiver.

2. The wireless downhole information transfer system according to claim 1, wherein the information signal is provided in the form of a trigger and/or a short pulse signal, and/or wherein the information signal can be coded to provide information to distinguishable receivers and/or to provide distinguishable information.

3. The wireless downhole information transfer system according to claim 1, wherein the information signal generator is designed as a transceiver, and/or the information signal receiver is designed as a transceiver.

4. The wireless downhole information transfer system according to claim 1, wherein the information signal is provided in form of a resonant frequency adapted to the properties of the elongated tubing, and/or adapted to the total distance between the information signal generator and the information signal receiver.

5. The wireless downhole information transfer system according to claim 1, further comprising one or more further information signal receivers arranged along or near the elongated tubing.

6. The wireless downhole information transfer system according to claim 1, wherein the information signal generator comprises at least one piezoelectric driver.

7. The wireless downhole information transfer system according to claim 6, wherein the piezoelectric driver comprises one or more piezoelectric discs stacked in a line, and/or wherein the information signal generator comprises two or more piezoelectric drivers, the two or more piezoelectric drivers arranged on opposing sides of an elongation axis of the tubing and/or arranged symmetrically or equiangular around the elongation axis of the tubing.

8. The wireless downhole information transfer system according to claim 1, wherein the information signal comprises a frequency in the range of 2 to 20 kHz.

9. The wireless downhole information transfer system according to claim 1, further comprising at least one repeater arranged between the information signal generator and the information signal receiver, and/or wherein at least one of the information signal receivers is a repeater designed to pass the information signal to the next repeater and/or to the information signal receiver arranged at or near the end section of the elongated tubing.

10. The wireless downhole information transfer system according to claim 9, wherein each repeater is designed to use a distinguishable coding, and/or wherein for each 1500 meters or more of elongation of the elongated tubing an additional repeater is used to amplify the information signal, or for each 1000 meters or more, or for each 500 meters or more, or for each 100 meters or more.

11. The wireless downhole information transfer system according to claim 1, wherein signal recognition is improved by means of autocorrelation, and/or wherein the receiver provides processing means designed to provide means for autocorrelation of the received information signal.

12. The wireless downhole information transfer system according to claim 1, the system providing autotuning capability, wherein both the signal generator and the signal receiver are designed as transceivers and wherein a frequency range is tested and at least one resonance frequency is acknowledged.

13. The wireless downhole information transfer system according to claim 1, wherein the information signal receiver is connected with one or more perforating units in a well bore, where the information signal comprises the firing signal for detonation of the firing unit or for detonation of one of the firing units.

14. The wireless downhole information transfer system according to claim 1, wherein the elongated tubing is made of metal.

15. The wireless downhole information transfer system according to claim 1, wherein the at least one information signal receiver comprises an energy storage in order to provide electric energy to the information signal receiver.

16. An information signal generator for transmission of an information signal along an elongated tubing, comprising at least one sound wave generator arranged perpendicularly or more or less perpendicularly with respect to the elongation axis of the elongated tubing for generation of torsional wave information.

17. The information signal generator according to claim 16, wherein the sound wave generator comprises one or more piezo discs.

18. The information signal generator according to claim 16, wherein the information signal generator is arranged at or near a top section of the elongated tubing and/or at an overhead portion of the elongated tubing.

19. The information signal generator according to claim 16, further comprising a circumferential portion, where the at least one sound wave generator is arranged on the circumferential portion, so that the at least one sound wave generator exposes the circumferential portion with at least one sound wave and the circumferential portion passes the at least one sound wave to the elongated tubing.

20. The information signal generator according to claim 19, wherein the circumferential portion converts the at least one sound wave emitted by the at least one sound wave generator into at least one torsional wave.

21. The information signal generator according to claim 19, wherein the circumferential portion comprises an inner side directed, when installed, towards the elongated tubing, and a circumferential constriction on said inner side.

22. The information signal generator according to claim 19, wherein the circumferential portion is mounted to the elongated tubing such as to comprise good surface contact by means of an increased contact pressure of the circumferential portion against the elongated tubing in order to improve signal propagation.

23. The information signal generator according to claim 16, wherein the sound wave generator comprises a stack of piezoelectric discs, and/or the sound wave generator comprises an end mass arranged on top of it, and/or the signal generator comprises two sound wave generators arranged more or less opposing each other, and/or the signal generator comprises several sound wave generators arranged more or less equiangular to each other, and/or the signal generator comprises at least two sound wave generators distributed along the elongation axis of the elongated tubing such that each sound wave generator is able to amplify the torsional wave information signal.

24. An information signal receiver for receiving a torsional wave information signal which propagated along an elongated tubing, the information signal receiver comprising: at least one transducer device designed for receiving said torsional wave information signal, and for converting said received torsional wave information signal, the transducer device being arranged at or near the elongated tubing and extending perpendicularly with respect to the elongation axis of the tubing, an outer shell shaped elongated or tube-like so as to fit into a wellbore or an elongated tubing.

25. The information signal receiver according to claim 24, further comprising at least a second transducer device arranged opposing the transducer device, and/or the transducer device or the second transducer device comprising one or more soundwave receivers.

26. The information signal receiver according to claim 24, further comprising an inner transducer mounting device, where the at least one transducer devices mounted on the inner transducer mounting device facing towards the outer shell of the information signal receiver.

27. The information signal receiver according to claim 25, the at least one transducer devices each comprising an end mass between the at least one soundwave receiver and the outer shell in contact with the soundwave receiver on the one side and the inner side of the outer shell on the other side.

28. The information signal receiver according to claim 24, further comprising a stand-alone power supply for storing electric energy, and/or an electronics compartment comprising an analog-to-digital converter.

29. The information signal receiver according to claim 24, further comprising a coupling for mounting the information signal receiver to the elongated tubing and/or to a consecutive compartment.

30. The information signal receiver according to claim 24, the receiver further comprising a sensor device such as a depth correlator or a pressure sensor.

31. The information signal receiver according to claim 24, the at least one transducer device comprising as the soundwave receiver a stack of piezoelectric plates, and/or the information signal receiver designed as a transceiver capable of receiving and transmitting torsional waves over the elongated tubing with its soundwave receivers.

32. The information signal receiver according to claim 24, wherein the transducer device is designed as to harvest energy from fluid movement of a wellbore fluid flowing through the elongated tubing.

33. A perforating gun for use with the downhole information transfer system of claim 1, the perforating gun comprising the information signal receiver according to claim 24.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0070] FIG. 1 a schematic cross-sectional view of an earth formation with a signal transmission system in a well (well bore);

[0071] FIG. 2 another schematic cross-sectional view of an earth formation with a signal transmission system in a well bore having a horizontal section partly covered by a liner;

[0072] FIG. 3 a signal generator mounted on a tubing section, perspective view;

[0073] FIG. 4 a signal generator mounted on a tubing, top view;

[0074] FIG. 5 photography of another signal generator mounted on a tubing;

[0075] FIG. 6 perspective view of an embodiment of a signal receiving unit;

[0076] FIG. 7 side view of an embodiment of a signal receiving unit;

[0077] FIG. 8 perspective view of a partly opened signal receiving unit;

[0078] FIG. 9 top view of a partly opened signal receiving unit;

[0079] FIG. 10 another perspective view of a partly opened signal receiving unit;

[0080] FIG. 11 side view of an embodiment for a downhole use of a signal transmission system with perforating guns.

DETAILED DESCRIPTION

[0081] In FIG. 1 a hole (well bore) 2 is drilled into an earth formation 4 to exploit natural resources like oil or gas. The well bore 2 continuously extends from the surface 6 to a reservoir 8. On top of the well bore a wellhead 10 is placed. The wellhead may include a “Christmas tree”. The well is connected to an extraction facility 9.

[0082] A casing 12 in the form of an elongated steel pipe or steel tubing is located within the well bore 2 and extending from the surface near the wellhead 10 to an underground section of the well bore 2. Inside the casing 12 a tubing 14 is arranged comprising several pipe sections 15 each connected to the consecutive pipe section 15 by means of any sort of coupling 18, for example screw-type couplings. In this embodiment, the first pipe section 152 is connected with the wellhead 10 and is comprising the signal generator 40. The “lowest” or last pipe section 154 comprises the signal receiver 20. As the tubing 14 is used as propagation carrier for the information signal along the downhole and/or along the tubing 14, the information transfer system comprises the signal generator 40 at the wellhead, the tubing 14 as signal carrier and the downhole signal receiver 20. The well bore is typically filled with a wellbore fluid 16. The well bore fluid can vary widely.

[0083] The wellbore could consist of mud (drilling fluid), brine (completion fluid), injection fluids (steam, CO.sub.2 or nitrogen) or fluids from the reservoir, such as water, oil and/or gas. These fluids may contain solids and deposits, such as sand particles, clay particles, scale deposits salts, barites, asphaltenes and polymers.

[0084] The tubing 14 thus typically only partly covers the well bore, as it is lowered just until the depth of interest, for example the depth in the wellbore where a perforating shall be undertaken, or where a valve shall be read out. The tubing 14 can be installed permanently in the well, or it can be lowered temporarily into the well, e.g. in the case of a planned perforation.

[0085] The signal receiver 20 is located in the well bore 2 as part of the tubing 14, thus comprising one pipe section 154 of the tubing 14. The signal receiver 20 operates autonomously having internal power storage 92 (see e.g. FIG. 6) and thus needs not be powered or wired externally. This eases installation and handling of the signal receiver 20, as no care has to be taken with respect to any wiring, and no limits have to be regarded with respect to depth of usage, which is total length of the tubing 14.

[0086] To sum up, the signal receiver 20 can be placed quite freely in the well bore 2 by means of adding pipe sections 15 to the tubing 14 between the first pipe section 152 and the last pipe section 154, whereby the signal receiver 20 is lowered into the well bore 2, and particularly needs not to be cable linked to the surface. It may be added, that the signal receiver 20 does not necessarily have to be installed to the last of the pipe sections 15, but other downhole means can be lowered farther down than the signal receiver 20, see e.g. FIG. 11 where a perforating gun 70 is mounted as the last pipe section 154, where the signal receiver 20 is installed above in another pipe section 15.

[0087] FIG. 2 shows another embodiment of an earth formation 2 with a signal receiver 20 positioned in a horizontal portion of the tubing 14. In this embodiment, the casing 12 as well as the tubing 14 ends in the well head 10. The signal generator 40 is arranged in or at the wellhead 10. The well 2 is drilled with an angle to the direction of production interest, in particular horizontally in the region of the last tube segment 154.

[0088] Turning to FIG. 3 an embodiment of a signal generator 40 is schematically shown mounted to a pipe section 15. The signal generator 40 comprises a circumferential portion 50 which is clamped to the pipe section 15 by means of fixation means 52. In order to further improve the contact pressure of the circumferential portion 50 on the pipe section 15, a constriction 42 is situated at the inner side of the circumferential portion 50. Two sound wave generators 44 are arranged on opposing sides of the pipe section 15, and are arranged perpendicular with respect to the elongation axis of the pipe section 15. The sound wave generators 44 can act a force on the circumferential portion, which in turn delivers this force to the pipe section 15, which starts a microscopic rotational movement in the pipe section 15. Thus, the sound wave generated by the sound wave generator 44 is converted into a torsional wave signal and imposed into the pipe section 15. The pipe section 15 then delivers the torsional wave signal along its extension and over any coupling 18 to the neighbouring pipe section 15, and thus along the elongated tubing 14 to the signal receiver 20.

[0089] FIG. 4 shows a top view on a pipe section 15 with a signal generator 40 mounted to it. The signal generator 40 has a circumferential portion 50 with a constriction 42 and two sound wave generators 44 opposing each other. Both sound wave generators 44 comprise a stack of several piezo discs 46 which together create the sound wave signal. The timing of the signal of the two sound wave generators 44 is done in such a way that both sound wave generator comprises the same signal phase, which then adds up to a total signal amplitude for stimulation of the torsional wave signal.

[0090] FIG. 5 shows a perspective photography of an embodiment of a signal generator 40 mounted to a pipe section 15. This signal generator 40 comprises four sound wave generators 44 mounted more or less equiangular around the pipe section 15, and more or less perpendicular to the elongation axis of the pipe. The piezo discs 46 are connected by means of electrical connections 54 in order to deliver an electrical current to the piezo discs 46, so that the piezo discs 46 as transducers convert the electrical current into the sound signal. The sound waves generated by the sound wave generator 44 then are converted into a torsional wave information signal, which can propagate along the pipe section 15 from the first pipe section 152 to the last pipe element 154 where the signal receiver 20 is mounted to.

[0091] Referring now to FIG. 6 a schematic perspective view of an embodiment of a signal receiver 20 is shown, where the various technical installations can be seen inside the signal receiver 20, which is placed in the housing 28. The housing 28 is sketched partly transparent for clarity reasons. The signal receiver 20 is designed to be mountable or pairable with other pipe sections 15 of the elongated tubing.

[0092] In this embodiment, an end cap is arranged on one side of the signal receiver 20, so that the signal receiving unit 20 may be mounted as the last pipe section 154, where other pipe sections 15 are connected to the signal receiving unit 20 by means of the coupling 18 arranged on the other side of the signal receiving unit 20. The signal receiver comprises a receiver 24 mounted on an inner transducer mounting device 30. The receiver 24 is wired by means of an electrical connection 54 to the electronics compartment 34, where for example an analog-to-digital converter and processing electronics may be situated. Further, a battery pack 92 is installed which provides electrical energy for operating the signal receiving unit 20.

[0093] The diameter of the housing 28 can be chosen e.g. with respect to the well bore diameter and/or the diameter of the tubing 14. The housing 28 may for instance have an outer diameter of 73 mm and an inner diameter of 55 mm, resulting in a housing thickness of about 18 mm. However, the outer diameter of the housing 28 lies preferably in a range in between 50 mm to 90 mm.

[0094] The signal receiving unit 20 further comprises a sensor 60, for example a pressure and temperature sensor and/or gamma ray detector, by means of which a depth in the well can be estimated. As an example in the embodiment, where the signal receiving unit 20 is placed to trigger an igniter of the perforating gun 70, the value measured from the pressure sensor 60 may be read out as a safety measure, where the receiving unit 20 can trigger the perforating gun 70. When the pressure is high enough the signal receiving unit 20 can trigger the igniter and the perforating guns 70 can be safely fired downhole. In summary, the signal receiver 20 is designed to receive the information signal comprising the activation signal for firing the perforating gun 70 sent by the signal generator 40 and the igniter can be triggered to fire the perforating gun 70.

[0095] FIG. 7 shows a side view of a signal receiving unit 20, where again inner parts are made visible in the housing 28, which is partly sketched transparent. Two signal receivers 24 are mounted on an inner transducer mounting device 30, the mounting plate.

[0096] In FIG. 8 another perspective view of a partly opened signal receiving device 20 is shown. In this figure the installation of the two signal receivers 24 is visible. The two signal receivers 24 are mounted on the inner transducer mounting device 30 Each signal receiver 24 comprises a stack of piezoelectric discs 46 as well as an end mass 48. The end mass is arranged in between the piezo discs 46 and the inner side 32 of the housing 28 and is in physical contact with the inner side of the housing 28 on one side and with at least one of the piezo discs 46 and/or the stack of piezo discs on its other side. This arrangement allows for a sensitive and at the same time space-efficient installation of the signal receivers 24.

[0097] FIG. 9 shows a sectional view through a signal receiving unit 20. In FIG. 9 the arrangement of the two signal receivers 24 is shown. The two signal receivers are in physical contact with the inner side 32 of the housing 28 by means of the end mass 48, which is arranged on top of a stack of piezo discs 46, which in turn are mounted on the transducer mounting device 30. The whole setup allows for a conduction of the torsional wave information signal to the signal receivers 24 to improve the signal to noise ratio of the received information signal.

[0098] In FIG. 10 a sectional perspective view of the electronics compartment 34 is shown, in which the battery pack 92 and some electronics 80 are installed, in this case a printed circuit board with some processing means.

[0099] FIG. 11 shows a setup for usage of the information transfer system as proposed herein. The signal generator 40 is installed near or at the wellhead 10, and one or several pipe sections 15 are arranged below the wellhead to the first signal receiving unit 20a installed below. The first receiving unit 20a is situated in the wellbore, for example several hundred meters or even several thousand meters down below the opening of the well bore, which is typically at surface.

[0100] Next to the first signal receiving unit 20a an igniter and perforating gun 70a is installed. The igniter and perforating gun 70a can be placed directly below the first signal receiving unit 20a. It can for example also be wire connected to the first signal receiving unit 20a, which is placed some ten or some hundred meters from the perforating gun. This setup might be chosen e.g. when the signal receiving units must be spaced at some distance from the detonation zones, which will be generated when the perforating guns are fired.

[0101] One or several further pipe sections 15 connect this perforating gun 70a with the second signal receiving unit 20b, which is installed next to a second perforating gun 70b. Another pipe section 15 is connected to the second perforating gun 70b with a third signal receiving unit 20c connected to a third perforating gun 70c and so forth. For example, ten perforating guns 70 could be run in the wellbore at the same time in this manner—and be fired one after another in only one run. By this, the tubing 14 needs only to be put in place in the well once for performing all necessary perforations in the well.

[0102] When the perforating guns 70, 70a, 70b, 70c are being fired, the first information signal is delivered to the last receiving unit. In the example of FIG. 11 this is the third receiving unit 20c. The information signal can comprise an encoded trigger signal for firing the third perforating gun 70c. The other signal receiving units 20a and 20b may receive this signal, but can be programmed not to trigger the perforating gun(s) associated to them. Additionally, or alternatively, the other signal receiving units 20a and 20b can be programmed to repeat or amplify the received trigger signal addressed to the third receiving unit 20c. Thus, the receiving units 20a and 20b can act as repeaters in the elongated tubing 15. When the third signal receiver 20c triggers the third perforating gun 70c it may be possible, that the third receiving unit 20c is no longer reachable due to malfunction or destruction. Due to this, the lowest perforating gun 70c should be fired first, and thereafter the proximate next perforating gun 70b, and finally 70a.

[0103] In other words, the present disclosure allows for firing of several perforating guns by an individual command for each gun. All of this can be done by only one downhole run instead of several runs. This will reduce the time required for perforating and therefore will result in less production deferment and consequently in additional revenues. The presented information transfer system also allows for safe information delivery over long distances, where wired communication is undesirable, or difficult, or even impossible due to high deviation of the wellbore. Furthermore, run of high/long cable lengths may lead to wire failures and is not necessary any longer.

[0104] It will be appreciated that the features defined herein in accordance with any aspect of the present disclosure or in relation to any specific embodiment of the disclosure may be utilized, either alone or in combination with any other feature or aspect of the disclosure or embodiments. In particular, the present disclosure is intended to cover an information signal delivery system to include any feature described herein, and a signal generator, an information signal receiver and a perforating gun. It will be generally appreciated that any feature disclosed herein may be an feature of the present disclosure alone, even if disclosed in combination with other features, irrespective of whether disclosed in the description, the claims and/or the drawings.

[0105] It will be further appreciated that the above-described embodiments of the present disclosure have been set forth solely by way of example and illustration of the principles thereof and that further modifications and alterations may be made therein without thereby departing from the scope of the disclosure.