Amoco Corporation

Steven A Morris

Houston B Mount, Ii

John T Penn

Chriswell G Hutchens

A method and apparatus for processing a signal generated by a borehole scanning system of the type in which periodic electrical firing pulses initiate a plurality of corresponding acoustic energy pulses which 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 which are detected and converted to electrical pulses. The electrical pulse is periodically sampled with each sample level being converted to a digital number. A counter initiates counting in response to the firing pulse preceding the sample electrical pulse. Upon detection of the peak of the electrical pulse, the counter count is stored. Upon detection of the electrical pulse again falling below a preselected level, the count is again stored. Then the time midway between the two stored counts is determined.

Method and apparatus for detecting the peak of an analog signal

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.

Method and apparatus for logging a borehole

Disclosed herein are methods for canceling acoustic reverberations caused when acoustic energy impinges a medium. In one method, a series of positive pulses of acoustic energy are transmitted and the amplitudes of the resulting acoustic reverberations are measured. Negative pulses of acoustic energy are then transmitted having amplitudes equal to the immediately preceding received acoustic reverberation and at a time later than the positive pulses so that the acoustic reverberations are driven to a null.

Method for acoustic reverberation removal

A method and apparatus for processing a signal generated by a borehole scanning system of the type in which periodic electrical firing pulses initiate a plurality of corresponding acoustic energy pulses which 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 which are detected and converted to electrical pulses. The electrical pulse is periodically sampled with each sample level being converted to a digital number. Each new digital sample number is compared to the maximum of the preceding digital sample numbers and stored if the new digital sample number exceeds that maximum. A counter initiates counting in response to the firing pulse preceding the sample electrical pulse. Upon detection of the peak of the electrical pulse, the counter count is stored, thus yielding both the peak value of the electrical pulse and the elapsed time between the preceding firing pulse and peak of the electrical pulse.

Apparatus for creating a video display from information generated by acoustically scanning a reflecting boundary circumferential of a borehole. A downhole tool generates a first signal each time a rotating transducer therein passes through magnetic north. Acoustic pulses emitted from the transducer are radially transmitted toward a borehole reflecting boundary. At least a portion of each pulse is reflected back to the transducer where the same is detected and converted to an electrical pulse representative of the reflected acoustic pulse. The peak of each electrical pulse is detected and the value digitized. A series of different addresses is associated with each digital value from a single 360.degree. borehole scan and the same are accumulated in a RAM with each digital value being stored therein at its associated address. A central processing unit selects a block of video memory locations in a video memory responsive to the magnetic north signal. The data stored in the RAM is transferred directly to the video memory by applying the RAM addresses, as the data is read out thereof, to the video memory thus transferring the data to the selected block of video memory locations. An address generator is provided for rapidly reading data from the video memory for generating a video display therefrom.

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Sand Springs, OK, United States of America

Steven A Morris