Method and apparatus for detecting torsional vibration with a downhole pressure sensor
First Claim
1. A method of detecting torsional vibration in a drillstring while conducting a drilling operation in a subterranean well, the method comprising:
- disposing a pressure sensor on the drillstring, the drillstring having a bottom hole assembly including a drill bit;
drilling a borehole to a first depth;
locating the pressure sensor adjacent the first depth;
sampling the pressure sensor adjacent the first depth during drilling of the borehole;
obtaining a first pressure data set;
comparing a plurality of values in the first pressure data set to a pre-determined threshold value;
identifying values of the first pressure data set that exceed the pre-determined threshold value;
determining whether the data set indicates torsional vibration in the drillstring;
sending a warning signal to the surface of the well if the data set indicates torsional vibration; and
changing a downlink signal frequency in response to the warning signal.
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Accused Products
Abstract
A method and apparatus for detecting torsional vibration, or stick-slip, in a drill string while drilling is described. The method comprises sampling a downhole pressure sensor and using embedded filter schemes and algorithms to determine, based on the pressure samples, whether torsional vibration is occurring in the drill string. The method may also include sending a warning signal to the surface of the well. The apparatus comprises a downhole assembly having a downhole receiver and a master controller. The downhole receiver comprises a pressure sensor, filter schemes, and algorithms for detecting torsional vibration. The downhole assembly may also include a downhole transmitter for sending a warning signal to the surface of the well.
60 Citations
20 Claims
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1. A method of detecting torsional vibration in a drillstring while conducting a drilling operation in a subterranean well, the method comprising:
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disposing a pressure sensor on the drillstring, the drillstring having a bottom hole assembly including a drill bit; drilling a borehole to a first depth; locating the pressure sensor adjacent the first depth; sampling the pressure sensor adjacent the first depth during drilling of the borehole; obtaining a first pressure data set; comparing a plurality of values in the first pressure data set to a pre-determined threshold value; identifying values of the first pressure data set that exceed the pre-determined threshold value; determining whether the data set indicates torsional vibration in the drillstring; sending a warning signal to the surface of the well if the data set indicates torsional vibration; and changing a downlink signal frequency in response to the warning signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of reducing noise caused by torsional vibration in a drillstring while drilling in a subterranean well, the drillstring being part of a drilling assembly having a mud pulse telemetry system capable of sending uplink or downlink signals, the method composing:
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detecting torsional vibration in the drillstring; and changing the downlink signal frequency such that the torsional vibration frequency does not interfere with the downlink signal frequency.
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13. A method of detecting torsional vibration in a drillstring while drilling in a subterranean well, the drillstring being part of a drilling assembly having a mud pulse telemetry system capable of sending uplink or downlink signals, the method comprising:
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sampling a downhole pressure sensor at a frequency of at least 1 Hertz to obtain a first data set; cross-correlating the first data set using a reference signal to obtain a second data set; peak-detecting the second data set to determine whether the second data set indicates torsional vibration in the drillstring; and sending a warning to the surface of the well if torsional vibration is indicated. - View Dependent Claims (14, 15)
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16. A drilling assembly for detecting torsional vibration in a drillstring located in a subterranean well, the assembly comprising:
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a drillstring having a bottom hole assembly including a drill bit; a pressure sensor disposed on the drillstring near the bottom hole assembly; a control system disposed on the drillstring adjacent the pressure sensor and in communication with the pressure sensor; and a scheme embedded in the control system adjacent the pressure sensor, the scheme including an algorithm for comparing a plurality of sampled pressures to a pre-determined threshold value, identifying sampled pressures that exceed the pre-determined threshold value, determining whether the drillstring is experiencing torsional vibration, and transmitting an instruction to change the downlink signal frequency in response to torsional vibration. - View Dependent Claims (17, 18, 19)
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20. A method of detecting torsional vibration in a drillstring while conducting a drilling operation in a subterranean well, the method comprising:
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disposing a pressure sensor on the drillstring, the drillstring having a bottom hole assembly including a drill bit; drilling a borehole to a first depth; locating the pressure sensor adjacent the first depth; sampling the pressure sensor adjacent the first depth during drilling of the borehole, the sampling occurring within a bore of the drillstring; obtaining a first pressure data set; determining whether the data set indicates torsional vibration in the drillstring; and wherein the determining occurs adjacent the first depth.
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Specification