Method and apparatus for logging a borehole
First Claim
1. A method for generating a signal containing information relating to the state of a borehole, said method being of the type in which acoustic energy pulses are transmitted from the central portion of the borehole toward the borehole wall in a plurality of radial directions and at a plurality of different depths thereby generating reflected acoustic pulses from a reflecting boundary adjacent the borehole which are indicative of the condition of the reflecting boundary, said method comprising the steps of:
- providing means in a downhole housing for substantially continuously rotating at a rate dependent upon a speed control signal supplied to said rotating means;
providing a transducer assembly on said rotating means, said transducer assembly including means for generating such acoustic energy pulses and means for receiving such reflected acoustic pulses;
generating in the housing a speed control signal for a selected controlled rate of substantially continuous rotation of the rotating means;
providing the speed control signal to the rotating means;
varying the rate of substantially continuous rotation of the rotating means while in the borehole; and
generating and without interrupting scanning, varying the rate of generating periodic pulses firing signals for producing such acoustic energy pulses while in the borehole.
1 Assignment
0 Petitions
Accused Products
Abstract
Method and apparatus for logging a borehole of the type in which an acoustic energy signal scans the borehole wall at a plurality of different depths thereby generating signals reflected from a reflecting boundary which are indicitative of the condition of the reflecting boundary. A downhole microcomputer generates a sync signal for firing a transducer thereby directing an acoustic pulse toward the borehole wall. The transducer is rotated by a stepper motor. The computer synchronizes the number of transducer pulses with the number of stepper motor pulses thereby generating a constant number of transducer pulses per motor revolution. Reflected acoustic energy generates an electrical pulse which is amplified and summed with a signal relating to the rotational orientation of the transducer and the occurrence of the transducer firing pulse. The summed signal provides information relating to the condition of the reflecting boundary and may be used to generate a video image thereof.
30 Citations
47 Claims
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1. A method for generating a signal containing information relating to the state of a borehole, said method being of the type in which acoustic energy pulses are transmitted from the central portion of the borehole toward the borehole wall in a plurality of radial directions and at a plurality of different depths thereby generating reflected acoustic pulses from a reflecting boundary adjacent the borehole which are indicative of the condition of the reflecting boundary, said method comprising the steps of:
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providing means in a downhole housing for substantially continuously rotating at a rate dependent upon a speed control signal supplied to said rotating means; providing a transducer assembly on said rotating means, said transducer assembly including means for generating such acoustic energy pulses and means for receiving such reflected acoustic pulses; generating in the housing a speed control signal for a selected controlled rate of substantially continuous rotation of the rotating means; providing the speed control signal to the rotating means; varying the rate of substantially continuous rotation of the rotating means while in the borehole; and generating and without interrupting scanning, varying the rate of generating periodic pulses firing signals for producing such acoustic energy pulses while in the borehole. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for generating a signal containing information relating to the state of a borehole, said method being of the type in which acoustic energy pulses are transmitted from the central portion of the borehole toward the borehole wall in a plurality of radial directions and at a plurality of different depths thereby generating reflected acoustic pulses from a reflecting boundary adjacent the borehole which are indicative of the condition of the reflecting boundary, said method comprising the steps of:
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providing means for rotating in a downhole housing; providing a transducer assembly on said rotating means, said transducer assembly including means for generating such acoustic energy pulses and means for receiving such reflected acoustic pulses; generating a command signal for a selected rate of acoustic pulsing, said command signal being generated on the surface adjacent said borehole; providing the command signal to the downhole housing; generating the periodic pulses firing signal in response to the command signal; generating a second command signal for a second selected rate of acoustic energy pulsing different from the first selected rate of acoustic energy pulsing, said second command signal being generated on the surface adjacent said borehole; providing the second command signal to the downhole housing; and generating a second rate of periodic pulsed firing signal in response to the second command signal.
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12. A method for using a well logging device of the type having a motor driven by a substantially square wave drive signal and a transducer assembly mounted on the shaft of said motor, said method comprising the steps of:
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generating a substantially square wave drive signal; providing the drive signal to the motor; generating a periodic pulsed firing signal; providing the periodic pulsed firing signal to the transducer assembly thereby generating acoustic energy pulses; advancing the motor along the axis of a wellbore with said transducer assembly oriented to radially transmit said acoustic energy pulses from the central portion of the wellbore toward the wellbore wall, said transducer assembly receiving reflected acoustic pulses from a reflecting boundary along a radial axis which are indicative of the condition of the reflecting boundary; and varying the speed of substantially continuous rotation of said motor while maintaining a substantially constant torque. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. Apparatus for logging a wellbore comprising:
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a housing receivable in a wellbore; means adjacent the housing for substantially continuously rotating at a rate dependent upon a drive signal supplied to said rotating means; means for generating acoustic energy pulses responsive to a periodic pulsed firing signal, said means for generating acoustic energy pulses being mounted on said rotating means; means in the housing for generating a substantially square wave drive signal operatively connected to said rotating means; means for varying the frequency of said drive signal while in the wellbore, said frequency varying means being operatively connected to said means for generating a drive signal for supplying a speed control signal thereto; means in the housing for generating a periodic pulsed firing signal operatively connected to said means for generating acoustic energy pulses; means for advancing said rotating means along the axis of a wellbore, said means for generating acoustic energy pulses being oriented to radially transmit said acoustic energy pulses from the central portion of the wellbore toward the wellbore wall when said rotating means is so advanced; and means for receiving reflected acoustic pulses mounted on said rotating means, said reflected acoustic pulses being reflected by a reflecting boundary along a radial wellbore axis and being indicative of the condition of the reflecting boundary. - View Dependent Claims (26, 27, 28, 29, 30)
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31. Apparatus for generating a signal containing information relating to the state of a borehole, said apparatus being of the type in which acoustic energy pulses are transmitted from the central portion of the borehole toward the borehole wall in a plurality of radial directions and at a plurality of different depths thereby generating reflected acoustic pulses from a reflecting boundary which are indicative of the condition of the reflecting boundary, said apparatus comprising:
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means adjacent a housing for substantially continuously rotating responsive to a substantially square wave drive signal, the rotational speed of said rotating means being directly related to the frequency of said drive signal; a transducer assembly mounted on said rotating means, said transducer assembly including means for generating such acoustic energy pulses and means for receiving such reflected pulses; means in the housing for generating a substantially square wave drive signal operatively connected to said rotating means; means for advancing said rotating means along the axis of said borehole; means for varying the frequency of said drive signal while it the borehole; means in the housing for providing a periodic pulsed firing signal to said transducer assembly for generating acoustic energy pulses; and means for varying the rate of generating said periodic pulsed firing signals without interrupting scanning while in the borehole. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. A method for using a well logging device of the type having a motor driven by a substantially square wave drive signal and a transducer assembly mounted on the shaft of said motor, said method comprising the steps of:
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generating a substantially square wave drive signal; providing the drive signal to the motor; generating a periodic pulsed firing signal;
providing the periodic pulsed firing signal to the transducer assembly thereby generating acoustic energy pulses;advancing the motor along the axis of a wellbore with said transducer assembly oriented to radially transmit said acoustic energy pulses from the central portion of the wellbore toward the wellbore wall, said transducer assembly receiving reflected acoustic pulses from a reflecting boundary along a radial axis which are indicative of the condition of the reflecting boundary; and
varying the speed of rotation of said motor while maintaining a substantially constant torque; andvarying the rate of the periodic pulsed firing signal whereby varying the rate of the acoustic energy pulses. - View Dependent Claims (45, 46, 47)
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Specification