MEASURING MICRO STALLS AND STICK SLIPS IN MUD MOTORS USING FIBER OPTIC SENSORS
First Claim
1. A method of measuring stick slips and micro stalls in a down-hole mud motor, the method comprising:
- positioning in a borehole a mud motor with an elastomeric stator and at least one fiber optic sensor within the elastomeric stator;
receiving a measurement from the fiber optic sensor corresponding to a strain within the elastomeric stator; and
processing the measurement to determine a frequency of at least one of a micro stall and a stick slip of the mud motor.
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Accused Products
Abstract
A fiber optic sensor is disposed in the elastomer of the stator of the mud motor in order to sense elastomer strain while drilling. The frequencies of micro stalls and stick slips are measured from the fiber optic sensor data by classification using thresholds or by converting time-domain measurements from the fiber optic sensor data to frequencies. For example, the frequencies are produced by accumulating a histogram over an interval of time or by computing a Discrete Fourier Transform over an interval of time. A plurality of fiber optic sensors also can sense angular position of the rotor of the mud motor for correlation of the micro stalls and stick slips with the angular position. The measurements of the micro stalls and stick slips are used to select remedial action such as changes in drilling parameters.
28 Citations
20 Claims
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1. A method of measuring stick slips and micro stalls in a down-hole mud motor, the method comprising:
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positioning in a borehole a mud motor with an elastomeric stator and at least one fiber optic sensor within the elastomeric stator; receiving a measurement from the fiber optic sensor corresponding to a strain within the elastomeric stator; and processing the measurement to determine a frequency of at least one of a micro stall and a stick slip of the mud motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for measuring stick slips and micro stalls of a down-hole mud motor, the system comprising:
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a downhole mud motor having a rotor, an elastomer stator, and a fiber optic sensor disposed in the elastomer of the stator; and a computer communicably coupled to the fiber optic sensor, wherein the computer has a data processor and a computer-readable storage device storing instructions that, when executed by the data processor, cause the data processor to receive data generated at the fiber optic sensor; and determine frequencies of the micro stalls and stick slips based, at least in part, on the received data. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A non-transitory computer-readable storage device storing instructions that, when executed by a data processor, cause the data processor to
receive data from a fiber optic sensor disposed in the elastomer of the stator of a mud motor, process the received data to determine a frequency of at least one of a micro stall and stick slip of the mud motor; - and
report the determined frequency. - View Dependent Claims (20)
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Specification