Optimizing downhole data communication with at bit sensors and nodes
Data is communicated from sensors at a downhole location near a drill bit to surface equipment. Communication to the surface equipment may be direct or may pass through a series of nodes. The nodes in some cases are intelligently reconfigured to achieve desired data rates, achieve power management goals, and/or compensate for failed nodes.
1. A method for transmitting data along a drill string, the method comprising:
transmitting a first signal from a first node based on a first transmission setting while the first node is located at a first depth;
measuring an aspect of the first signal at a second node;
determining a second transmission setting based on the measurement of the measured aspect of the first signal;
advancing the drill string so that the second node is proximate to the first depth; and
transmitting a second signal at the second transmission setting from the second node while the second node is located proximate to the first depth.
2. A method according to claim 1 wherein the aspect comprises a signal strength of the first signal at the second node.
3. A method according to claim 1 wherein the aspect comprises a signal-to-noise ratio of the first signal at the second node.
4. A method according to claim 1 wherein the aspect comprises a harmonic frequency of the first signal.
5. A method according to claim 1 comprising configuring the first node to transmit a signal based on the second transmission setting.
6. A method according to claim 1 wherein the setting comprises a frequency setting.
7. A method according to claim 1 wherein the setting comprises an amplitude setting.
8. A method according to claim 1 wherein the setting comprises a gain setting.
9. A method according to claim 1 comprising transmitting signals from the first node at a first frequency and receiving signals at the first node at a second frequency, wherein the first frequency is different from the second frequency.
10. A method according to claim 9 comprising transmitting signals from the second node at the second frequency and receiving signals at the second node at the first frequency.
11. A method according to claim 9 comprising filtering out the first frequency at a receiver of the first node.
12. A method according to claim 9 comprising filtering out a plurality of frequencies including the first frequency at a receiver of the first node.
13. A method according to claim 9 wherein filtering out the first frequency at a receiver of the first node comprises using harmonic separation.
14. A method according to claim 1 comprising transmitting signals from the first node at a first polarity and transmitting signals at the second node at a second polarity, the first polarity opposing the second polarity.
15. A method according to claim 1 wherein transmitting a second signal at the second transmission setting comprises decoding and buffering the first signal.
16. A method according to claim 1 wherein transmitting a second signal at the second transmission setting comprises adding additional data to the first signal.
17. A method according to claim 16 wherein adding additional data to the first signal comprises providing a node identifier with the additional data.
18. A method according to claim 17 wherein the node identifier comprises a time stamp.
19. A method according to claim 17 wherein the node identifier comprises an incremental count.
20. A method according to claim 1 wherein the first node and the second node each comprise an electrically insulating gap and an electromagnetic telemetry transceiver.
21. A method according to claim 9 wherein transmitting signals at the first and second frequencies comprises transmitting signals in a first direction.
22. A method according to claim 21 comprising transmitting signals in a second direction using a third and fourth frequency wherein the first, second, third and fourth frequencies are different from one another and the first direction is opposite the second direction.
23. A method according to claim 22 wherein each of the third and fourth frequencies are lower than each of the first and second frequencies.
24. A method according to claim 1 comprising increasing a gain value of the second transmission setting with depth.
25. A method according to claim 1 comprising decreasing a power value of the second transmission setting with depth.
26. A system for transmitting data along a drill string, the system comprising:
a first node operable to transmit signals positioned along the drill string, the first node in communication with one or more sensors, the first node configured to transmit a first signal based on a first transmission setting;
a second node operable to transmit signals positioned along the drill string and spaced apart from the first node, the second node in communication with the first node, the second node configured to measure an aspect of the first signal transmitted by the first node while the first node is located at a first depth; and
a controller configured to determine a second transmission setting based on the aspect of the first signal measured by the second node;
wherein the second node is configured to transmit a second signal at the second transmission setting while the second node is located proximate to the first depth.
27. A system according to claim 26 wherein the first node is configured to transmit signals at a first frequency and receive signals at a second frequency, wherein the first frequency is different from the second frequency.
28. A system according to claim 27 wherein the second node is configured to transmit signals at the second frequency and receive signals at the first frequency.
29. A system according to claim 28 wherein the first node is configured to filter out at least the first frequency at a receiver of the first node.
30. A system according to claim 29 wherein the first node comprises a filter connected to block at least the first frequency from reaching the receiver of the first node.
31. A system according to claim 30 wherein blocking at least the first frequency from reaching the receiver of the first node comprises using harmonic separation.
32. A system according to claim 26 wherein the first node is configured to transmit signals at a first polarity and the second node is configured to transmit signals at a second polarity, the first polarity opposing the second polarity.
33. A system for transmitting data along a drill string, the system comprising:
a first plurality of nodes operable to transmit signals positioned along the drill string, each one of the first plurality of nodes in communication with one or more sensors and configured to transmit a signal based on a transmission setting for the node;
a second plurality of nodes operable to transmit signals positioned along the drill string, wherein each one of the second plurality of nodes is in communication with a corresponding one of the first plurality of nodes and is configured to measure an aspect of the signal transmitted by the corresponding one of the first plurality of nodes; and
a controller configured to determine a transmission setting for each one of the second plurality of nodes based on the aspect of the signal measured by the node;
wherein for each one of the second plurality of nodes, the node is configured to transmit a signal at the transmission setting for the node while the node is located proximate to a depth of the corresponding one of the first plurality of nodes when an aspect of the signal transmitted therefrom was measured.
34. A system according to claim 33 wherein the first plurality of nodes is configured to transmit signals at a first frequency and receive signals at a second frequency, wherein the first frequency is different from the second frequency.
35. A system according to claim 34 wherein the second plurality of nodes is configured to transmit signals at the second frequency and receive signals at the first frequency.
36. A system according to claim 35 wherein each one of the first plurality of nodes is configured to filter out at least the first frequency at a receiver of the node.
37. A system according to claim 36 wherein each one of the first plurality of nodes comprises a filter connected to block at least the first frequency from reaching the receiver of the node.
38. A system according to claim 37 wherein blocking at least the first frequency from reaching the receiver of the node comprises using harmonic separation.
39. A system according to claim 38 wherein the first plurality of nodes is configured to transmit signals at a first polarity and the second plurality of nodes is configured to transmit signals at a second polarity, the first polarity opposing the second polarity.