DOWNHOLE ENERGY HARVESTING SYSTEM

Abstract

A downhole energy harvesting system configured for use in a downhole tool. The system utilizes at least one harvesting antenna supported within the downhole tool. During operation, the harvesting antenna harvests energy from a beacon signal emanating from a beacon included in the downhole tool. The harvested energy is used to power electronics included within the downhole tool during the course of a boring operation.

Claims

1. A kit, comprising: a beacon comprising a transmitting antenna, the transmitting antenna configured to emit a dipole magnetic field; a harvesting antenna, configured to receive the dipole magnetic field and convert the dipole magnetic field into power; and electronics configured to detect information about an underground boring operation, wherein the electronics are provided power from the harvesting antenna.

2. The kit of claim 1 wherein the electronics comprise: an energy storage device, configured to receive power from the harvesting antenna; and a plurality of sensors, configured to receive power from the energy storage device.

3. The kit of claim 2 wherein the electronics further comprise a first radio, configured to receive power from the energy storage device and to transmit a first signal, the first signal containing information received from the plurality of sensors.

4. The kit of claim 3 wherein the beacon further comprises a second radio, configured to receive the first signal.

5. The kit of claim 4 wherein the transmitting antenna is configured to encode a second signal on the dipole magnetic field, wherein the second signal contains information received on the first signal by the second radio.

6. The kit of claim 5 in which the first radio and the second radio comprise Bluetooth radios.

7. A downhole tool comprising: a beacon housing disposed on a drill string; and the kit of claim 1, in which the beacon is situated within the beacon housing and the electronics are situated outside of the beacon housing.

8. The kit of claim 1, in which the harvesting antenna is a first harvesting antenna, the kit further comprising: a second harvesting antenna configured to receive the dipole magnetic field and convert the dipole magnetic field into power; in which the electronics are provided power from the second harvesting antenna.

9. The kit claim 1, in which the harvesting antenna communicates with the electronics via a rectifier circuit.

10. The kit of claim 1, in which the harvesting antenna is a ferrite rod.

11. The kit of claim 1, in which the harvesting antenna is a PCB antenna.

12. The kit of claim 1, further comprising a tracker, wherein the tracker comprises a receiving antenna configured to receive the dipole magnetic field.

13. A system for monitoring a horizontal boring operation, comprising: an above-ground horizontal directional drilling machine; a drill string, extending from the above-ground horizontal directional drilling machine to a below-ground location; a downhole tool comprising a beacon housing, supported by the drill string at the below-ground location; and the kit of claim 12, wherein: the beacon is disposed within the beacon housing; and the electronics are supported by the drill string outside of the beacon housing.

14. The system of claim 13 wherein: the electronics comprise: a first Bluetooth radio, powered by the harvesting antenna; and a first sensor, powered by the harvesting antenna; and wherein: the first sensor provides data to the first Bluetooth radio and the first Bluetooth radio transmits the data to the beacon.

15. The system of claim 14 wherein the beacon transmits the data to the tracker via the dipole magnetic field.

16. A downhole tool, comprising: a beacon configured to emit a magnetic dipole field; an elongate housing having an exterior surface within which a cavity is formed, the cavity receiving the beacon and having an open mouth that joins the exterior surface of the housing; a lid configured to close the mouth of the cavity; a harvesting antenna situated within a pathway of the emitted magnetic dipole field; and an energy storage device in communication with the harvesting antenna.

17. The downhole tool of claim 16, in which the harvesting antenna is a ferrite rod situated in a parallel-relationship with the beacon.

18. The downhole tool of claim 16, further comprising: one or more sensors in communication with the energy storage device; a first radio in communication with the energy storage device and the one or more sensors; and a second radio in communication with the beacon and the first radio.

19. The downhole tool of claim 18 in which the first radio is configured to transmit data to the second radio at intervals.

20. The downhole tool of claim 18 in which the first radio is configured to transmit data to the second radio in response to a critical data measurement by the one or more sensors.

21. The downhole tool of claim 18 in which the one or more sensors comprise a pressure sensor and an accelerometer.

22. The downhole tool of claim 16 in which the energy storage device comprises a battery.

23. A method of using the downhole tool of claim 16, comprising: emitting the magnetic dipole field from the beacon; receiving the magnetic dipole field at the harvesting antenna; converting the magnetic dipole field into power at the harvesting antenna; charging the energy storage device with the power from the harvesting antenna; with the energy storage device, operating one or more sensors to generate a first data packet; with a radio powered by the energy storage device, transmitting the first data packet to the beacon; and encoding the first data packet on the magnetic dipole field.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is an illustration of a horizontal directional drilling operation.

[0010] FIG. 2 is a side perspective view of one embodiment of a downhole tool.

[0011] FIG. 3 is a side perspective and exploded view of the downhole tool shown in FIG. 2.

[0012] FIG. 4 is a cross-sectional view of the downhole tool shown in FIG. 2, taken along line A-A. The beacon installed within the downhole tool is not shown in cross-section.

[0013] FIG. 5 is an enlarged view of area B shown in FIG. 4.

[0014] FIG. 6 is a cross-sectional view of the beacon shown in FIGS. 3 and 4, taken along a longitudinal axis of the beacon.

[0015] FIG. 7 is the cross-sectional view of the downhole tool shown in FIG. 4, but one embodiment of a downhole energy harvesting system is shown installed within the downhole tool and the beacon is shown in cross-section.

[0016] FIG. 8 is a simplified drawing of a perspective and cross-sectional view of the downhole tool and installed downhole energy harvesting system shown in FIG. 7, but the lid has been removed from the downhole tool and the circuit board is shown in a perspective and top plan view. A drill bit is also shown attached to the downhole tool.

[0017] FIG. 9 is a diagram of the interaction between the transmitting antenna and harvesting antennas shown in FIGS. 7 and 8 during operation.

[0018] FIG. 10 is the simplified drawing of a perspective and cross-sectional view of the downhole tool shown in FIG. 8, but another embodiment of a downhole energy harvesting system is shown installed therein.

[0019] FIG. 11 is a diagram of the interaction between the transmitting antenna and harvesting antennas shown in FIG. 10 during operation.

DETAILED DESCRIPTION

[0020] With reference to FIGS. 7-11, the present application discloses various embodiments of downhole energy harvesting systems. One embodiment of a downhole energy harvesting system 100 is shown in FIGS. 7-9. Another embodiment of a downhole energy harvesting system 200 is shown in FIGS. 10 and 11. The systems 100 and 200 are configured to be installed within a downhole tool, such as the embodiment of a downhole tool 42 shown in FIGS. 2-5. As will be described in more detail herein, the systems 100 and 200 are configured to continually harvest power from the beacon signal 44 emanating from the beacon 46 installed within the downhole tool 42, as shown in FIGS. 8 and 10. The harvested power is used to power one or more sensors 48 or 49 and other electronics installed within the downhole tool 42, but outside of the beacon housing 84, throughout the course of the boring operation.

[0021] Turning to FIGS. 2-5, the downhole tool 42 is shown in more detail and will be described prior to describing the downhole energy harvesting systems 100 and 200 to be installed therein. The downhole tool 42 is just one embodiment of a downhole tool that may utilize the systems 100 and 200 or other systems disclosed herein. Other embodiments of downhole tools known in the art and not shown herein may also be used.

[0022] Continuing with FIG. 2, the downhole tool 42 comprises an elongate housing 50 having opposed first and second ends 52 and 54 and an exterior surface 56. A plurality of bit connectors 58, configured to secure a drill bit 60 to the downhole tool 42, as shown in FIGS. 8 and 10, are supported on the first end 52 of the housing 50. The second end 54 of the housing 50 is configured to attach to the second end 28 of the drill string 20, as shown in FIG. 1.

[0023] Turning to FIG. 3, a cavity 62 is formed within the housing 50 for receiving the beacon 46. The cavity 62 extends parallel to a longitudinal axis of the housing 50 and has an open mouth 64 that joins the exterior surface 56 of the housing 50. The mouth 64 is covered by a lid 66, as shown in FIG. 2. An interior surface 68 of the lid 66 is sized to receive a circuit board 68. The circuit board 68 is configured to support a plurality of various electronics that are better served positioned outside of the beacon housing 84. The electronics may comprise one or more sensors, a microprocessor, an energy storage device, etc. The embodiment shown in FIGS. 3-5 comprises the pressure sensor 49. In alternative embodiments, the one or more sensors may comprise, for example, a temperature sensor, a tension sensor, an accelerometer, an inclinometer, etc., in place of or in addition to the pressure sensor 49.

[0024] Continuing with FIGS. 3 and 6, the beacon 46 is configured to encode the data from the sensors, such as the pressure sensor 49, into the beacon signal 44 to be transmitted to the above-ground tracker 32. Because the sensors, such as the pressure sensor 49, are positioned outside of the beacon housing 84, the electronics further comprise devices needed to allow communication between the sensors and the beacon 46. Such communication devices may comprise antennas, radios, or other devices capable of communicating with one another. For example, the embodiments shown in FIGS. 3, 8, and 10 utilize a Bluetooth radio 70. The Bluetooth radio 70 is configured to transmit data received by the sensors to another Bluetooth radio 72 included in the beacon 46, as shown in FIG. 6.

[0025] Turning to FIGS. 4 and 5, when the circuit board 68 is installed within the lid 66, the lid 66 may be characterized as having layers. An exterior surface 74 of the lid 66 may be characterized as an outer layer 76, the circuit board 68 may be characterized as an inner layer 78 of the lid 66, and the electronics supported on the circuit board 68, including the pressure sensor 49, may be characterized as an intermediate layer 80 of the lid 66, as shown in FIG. 5.

[0026] Continuing with FIG. 6, the tubular housing 84 of the beacon 46 is sealed closed by end caps 86 and is made of a non-conductive material, such as plastic. In addition to the transmitting antenna 82 and the battery 87, a processor 90, the Bluetooth radio 72, and other electrical circuitry may also be included within the tubular housing 84. As shown in FIGS. 8 and 10, during operation, the transmitting antenna 82 emits the beacon signal 44 from the beacon 46. The beacon signal 44 comprises a plurality of flux lines 92 that emanate from the beacon 46.

[0027] Turning back to FIG. 3, the downhole tool housing 50 and the lid 66 are preferably made of a durable ferrous metal so as to not break during drilling operations. However, ferrous metals attenuate the beacon signal 44. To allow the beacon signal 44 to escape from the housing 50, a window 92 is formed in the lid 66, as also shown in FIG. 2. The window 92 is characterized by an elongate slot and is positioned directly above the beacon 46 when the lid 66 is attached to the housing 50. The window 92 provides an opening for the beacon signal 44 to pass through the housing 50 during operation. The window 92 may be filled with a non-ferrous material, such as plastic or silicon. One or more additional slots may be formed in the housing 50 to serve as additional antenna windows for the beacon signal 44.

[0028] Turning now to FIGS. 7-9, the downhole energy harvesting system 100 is shown. The system 100 is shown installed within the downhole tool 42 in FIG. 7 and is shown installed within a simplified drawing of the downhole tool 42 with the lid 66 removed in FIG. 8. The same reference numbers will be used in FIG. 8 to designate the same components shown in FIG. 7, for ease of reference. The embodiment shown in FIG. 7 comprises the pressure sensor 49, while the embodiments shown in FIG. 8 comprises two sensors 48. However, in alternative embodiments, only one sensor 48 or more than two sensors 48 may be used. The sensors 48 may comprises any type of sensor known in the art to be used in a downhole tool, such as the previously mentioned pressure sensor, temperature sensor, tension sensor, an accelerometer, an inclinometer, etc.

[0029] The downhole energy harvesting system 100 comprises a first and second harvesting antenna 102 and 104 supported on the circuit board 68. The harvesting antennas 102 and 104 may be considered as part of the intermediate layer 80 of the lid 66. The harvesting antennas 102 and 104 are spaced apart from one another and each positioned near an end of the transmitting antenna 82 such that each antenna 102 and 104 is situated within a pathway of the emitted magnetic or beacon signal 44.

[0030] The harvesting antennas 102 and 104 shown in FIGS. 7-9 are each a ferrite rod. The ferrite rods are positioned so that a longitudinal axis of each rod lies parallel to a longitudinal axis of the transmitting antenna 82. In such position, the flux lines 92 emanating from the beacon 46 are also in a parallel relationship with the ferrite rods, as shown in FIG. 9. Such positioning concentrates the beacon signal 44 received by the antennas 102 and 104. In operation, each harvesting antenna 102 and 104 harvests or captures electromagnetic energy from the beacon signal 44 as it emanates out of the beacon 46.

[0031] In another embodiment, a single longer ferrite rod may be used in place of the two smaller and spaced-apart ferrite rods making up the harvesting antennas 102 and 104. However, using two smaller ferrite rods frees space for other electronics on the circuit board 68. For example, in FIGS. 7 and 8, the Bluetooth radio 70 is shown positioned between the harvesting antennas 102 and 104.

[0032] Continuing with FIGS. 7 and 8, the downhole energy harvesting system 100 further comprises a rectifier circuit 106 and an energy storage device 108 supported on the circuit board 68. Such components may also be considered part of the intermediate layer 80 of the lid 66. The energy storage device 108 may comprise a supercapacitor, battery, or other energy storage device known in the art. Energy harvested by each harvesting antenna 102 and 104 is transmitted to the rectifier circuit 106 where it is converted into usable continuous voltage energy. The converted energy is then transmitted to the energy storage device 108 where it is stored.

[0033] Energy stored in the storage device 108 is used to power the sensors 48 or 49 or other electronics, such as the Bluetooth radio 70, supported within the downhole tool 42. The harvesting antennas 102 and 104 may be characterized as being in communication with the energy storage device 108. Such communication is facilitated by the rectifier circuit 106. The energy storage device 108 is further in communication with the sensors 48 or 49 and other electronics.

[0034] The harvesting antennas 102 and 104 are configured to harvest power at a plurality of different frequencies within a frequency range, such as anywhere between 12 kHz and 46 kHz, for example. Specifically, the harvesting antennas 102 and 104 are configured to harvest power at the lowest frequency range, usually 12 kHz, but potentially lower. The lowest frequency ranges are the most difficult to harvest. In contrast, the higher the frequency, the easier it is to harvest energy. If the harvesting antennas 102 and 104 can capture energy at the lowest frequency, the antennas 102 and 104, as a matter of course, can capture energy from any frequency there above. Likewise, the harvesting antennas 102 and 104 are configured to harvest energy from the beacon signal 44 at a wide range of power levels. The higher the level of power the beacon signal 44 is transmitted at, the easier it is to harvest.

[0035] Configuring the antennas 102 and 104 to respond to a large range of frequencies ensures that energy is harvested from the magnetic signal 44 no matter what frequency the transmitting antenna 82 is tuned to. Some beacons can transmit the beacon signal 44 over a wide range of frequencies, for example, 32 different frequencies. The beacon 46, for example, may be configured to switch frequencies, at the direction of an operator, one or more times during the course of a single boring operation. Likewise, configuring the antennas 102 and 104 to respond to a large range of power levels ensures energy is harvested no matter the power level of beacon signal 44.

[0036] In summary, the harvesting antennas 102 and 104 are preferably configured to harvest power even when the transmitting antenna 82 is transmitting at the worst case harvesting scenario, the lowest frequency and low power. Even in this scenario, the harvesting antennas 102 and 104 can harvest enough power to adequately charge the energy storage device 108. However, the higher the frequency and power level, the faster the energy storage device 108 is charged.

[0037] During operation, the harvested energy may be stored temporarily in the energy storage device 108 and used only when needed for certain electronics. For example, it takes a lot of energy for the Bluetooth radio 70 to transfer its data to the beacon 46, but the data may not need to be transmitted very oftenfor example, every 30 seconds. In such case, the energy storage device 108 may be configured to store energy for 30 seconds before powering the Bluetooth radio 70 long enough to burst the data to the beacon 46. The Bluetooth radio 70 is then powered down between data transmission sessions.

[0038] As another example, energy may be harvested until the energy storage device 108 has enough energy to power the sensors 48 or 49, the Bluetooth radio 70, and/or other electronics powered by the energy storage device 108. Once the energy storage device 108 has enough power stored up, it powers the needed electronics and then begins storing energy again. In such embodiment, the energy storage device 108 may not power any electronics for extended periods of time or at non-uniform intervals.

[0039] As another example, the energy storage device 108 may be configured to store energy until energy is needed. For example, the Bluetooth radio 70 may be turned off until the system recognizes that the sensors 48 or 49 have measured critical datafor example, a pressure sensor measures a high level of downhole pressure. Upon measuring the critical data, energy stored within the energy storage device 108 is sent to the Bluetooth radio 70, allowing the radio to transmit the critical data to the beacon 46. In such embodiment, the energy storage device 108 may not power any electronics for extended periods of time, helping to ensure that the energy storage device 108 is charged when power is needed.

[0040] Turning now to FIGS. 10 and 11, the downhole energy harvesting system 200 is shown. Like FIG. 8, the system 200 is shown installed within a simplified drawing of the downhole tool 42 in FIG. 10. The system 200 functions in the same manner as the system 100, but the system 200 utilizes another embodiment of harvesting antennas 202 and 204. Like the antennas 102 and 104, the antennas 202 and 204 are situated within a pathway of the emitted magnetic or beacon signal 44.

[0041] Instead of ferrite rods, the harvesting antennas 202 and 204 are PCB trace antennas supported on the circuit board 68. The harvesting antennas 202 and 204 may be considered as part of the intermediate layer 80 of the lid 66. The harvesting antennas 202 and 204 are spaced apart from one another and each positioned near an end of the transmitting antenna 82. Each harvesting antenna 202 and 204 is positioned so that the flux lines 92 intersect a longitudinal axis of each antenna 202 and 204 at a relatively perpendicular or non-zero angle, as shown in FIG. 11. Such positioning concentrates the beacon signal 44 received by the antennas 202 and 204.

[0042] In other embodiments, the harvesting antenna or antennas may comprise hand wound magnet wire or other types of antennas known in the art. The chosen system may be configured to store energy and power the electronics using any number of time intervals or methods, including those not specifically described herein.

[0043] If desirable, the harvesting antenna or antennas may also be configured to harvest power from a magnetic field at a single frequency, rather than a range of frequencies. This embodiment may be desirable if the beacon only emits a single frequency throughout the course of the boring operation. In such case, only a single one of the harvesting antennas 102, 104, 202, or 204 disclosed herein may be needed to harvest an adequate amount of energy from the magnetic signal.

[0044] In further alternative embodiments, the downhole energy harvesting systems disclosed herein may be incorporated into other embodiments of downhole tools. For example, such downhole tools may comprise other embodiments of lids or other methods of supporting the electronics within the housing of the downhole tool. For example, the electronics, including the sensors, and the components used with the systems 100 or 200 may be supported within a cavity formed in the interior of the downhole tool 42 instead of being supported within the lid 66. Thus, the electronics and the components of the systems 100 or 200 would be supported within the downhole tool 42 below the beacon 46, rather than above. The systems 100 or 200 would function in the same manner as described herein.

[0045] The various features and alternative details of construction of the apparatuses described herein for the practice of the present technology will readily occur to the skilled artisan in view of the foregoing discussion, and it is to be understood that even though numerous characteristics and advantages of various embodiments of the present technology have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the technology, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present technology to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.