Abstract: An apparatus useful in investigating the wall surfaces of a structure defining a cavity comprising: a tool having a periphery and being capable of being at least partially located in the cavity; and a plurality of transducers located at different points on the periphery of the tool, each of the transducers being capable of sending first signals toward the wall surfaces of the cavity and receiving reflected second signals. An improved method for investigating the wall surfaces of a structure defining a cavity is also disclosed.

Abstract: Amplifier gain is time ramped to increase amplification of the signal with increasing mud transit time and attenuation. Amplitude, ramp slope, and ramp onset time are independently controllable from the surface.

Abstract: An apparatus and method of visually examining the sidewalls of a bore hole include a down hole video tool lowered into the bore hole by means of a cable and winch on the surface. The apparatus includes a wide angle video camera at its lower section. An upper section houses a power supply/triplexer, a telemetry board, an FM modulator video amplifier transmission board, gyroscope data interface board, and a gyroscope for showing the directional orientation of the camera and apparatus in the bore hole. The gyroscope orientation and the visual image of the portion of the sidewall viewed is transmitted to a video display monitor in an equipment van on the surface. The image on the screen includes a directional reference point so that the direction of a portion of the sidewall being viewed can be ascertained. The camera images are recorded by a video cassette recorder for a permanent record of the visualization of the entire length of the bore hole.

Abstract: The microstructure of thinly laminated earth formations is acoustically determined with a logging tool having an acoustical transducer pad mounted for measuring while in contact with the borehole wall.

Abstract: A system is disclosed for creating a three-dimensional image of data obtained from scanning a borehole wall with an acoustic transducer. Each scan produces an orientation pulse and a series of signals, including a fire pulse and echo signals. The system uses the transit times of the echo signals to modulate the geometry of the three-dimensional image, and uses the amplitudes of the echo signals to control the gray scale shading of the image. In one embodiment, a counting means keeps track of the angular position of the transducer, a ramp generating means produces a ramp voltage proportional to the elapsed time since the fire pulse, a sine table means and a sine conversion means produce a sine signal proportional in amplitude to the ramp voltage, a cosine table means and a cosine conversion means produce a cosine signal porportional in amplitude to the ramp voltage, and a monitoring means displays points on the monitoring means when the echo signals are received.

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.

Abstract: A borehole televiewer apparatus includes a housing section having a cavity for the disposition of an acoustic signal transmitting and receiving transducer. An elongated threaded rod is disposed in the cavity and held stationary relative to the housing and supports a nut, a slipring assembly, the transducer and a drive motor assembly for axially translating the transducer and rotating the transducer while precluding rotation of the motor and a support plate therefor relative to the rod. The support plate is keyed to the rod by an elongated key and keyway configuration to prevent rotation of the motor and the support plate while permitting axial translation of the motor and support plate along the rod.

Abstract: A process for modeling a bounded volume having a given geologic stratigraphic pattern, other than a volume having layers of uniform thickness parallel to mean sea level. The process comprises the steps of constructing a separate grid for each critical surface bounding said volume and constructing layers of cells according to the stratigraphic pattern.

Abstract: Data received from a sonde in a borehole is enhanced by first measuring the relative travel time of a signal transmitted from the sonde and reflected from an area in the wall of a borehole. This measurement is repeated for a plurality of angles in a horizontal plane. From this plurality of travel times a best fit ellipse or circle is calculated and the travel times are correlated with the best fit ellipse or circle to provide corrected travel times and to determine the eccentricity of the sonde in the borehole. The corrected travel times are displayed as images to indicate the detailed shape properties of the borehole.

Abstract: In connection with a borehole televiewer system (10), the delta time (51) between low threshold (54) crossing (T.sub.1) and signal peak arrival (T.sub.2) provides a measure of mudcake (43) thickness.

Abstract: 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.

Abstract: 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.

Abstract: Method and apparatus for storing, displaying and processing borehole televiewer signals, comprises digitizing means for the electrical scan signals (ESS), and for storing them in a register at slow input rates until a full 360.degree. scan is completed. A RAM provides storage for a full frame of T.V. raster scan signals, which are being withdrawn from the RAM, to the TV monitor, and back to the RAM. As complete rotary ESS are accumulated they are injected into the stream of circulating video signals to add a new line. Then a second line is accumulated at slow scan rate, read out at TV raster scan rate to add a second line to update the display, and so on. Means are provided for processing the data stored in the RAM in a variety of ways.

Abstract: A borehole televiewer logging tool employs a transducer assembly having a transmitter of acoustic energy pulses and a receiver of acoustic energy pulses representing reflections of the transmitted acoustic energy pulses from the walls of a borehole traversing a subsurface formation. The transducer assembly is rotated within the borehole and also advanced along the borehole. The received reflection signals are corrected for amplitude modulation resulting from oblique angles of incidence of the transmitted acoustic energy pulses when the logging tool is off-center of the borehole, is in an eliptical borehole, or is tilted from the vertical axis of the borehole. The corrected reflection signals modulate an image display so that the full 360.degree. of the borehole wall can be delineated.

Abstract: The present invention is an improved mud excluder fitted around a rotating acoustic transducer of a borehole televiewer to exclude mud from the borehole televiewer. This mud excluder has:(a) a flexible casing means attached to the borehole televiewer to form a fluid cavity adjacent to the rotating acoustic transducer,(b) an acoustically transparent fluid located within the fluid cavity,(c) an acoustic window means opposite the transducer and adjacent to the fluid cavity, and(d) a pressure compensating means within the fluid cavity to equalize the pressure within the fluid cavity with the pressure on the outside of the flexible casing means.

Abstract: A method for determining the true dip and azimuth of bedding planes in a formation penetrated by a borehole using borehole televiewer measurements. The method corrects for borehole deviation and for inclination of the earth's magnetic field.

Abstract: A borehole televiewer circuit for compensating for out-of-roundness of a borehole. The circuit comprises an automatic gain control circuit having time constants that allow detection of borehole anomalies while having a fast enough rise time to adjust for the effects of out-of-roundness.

Abstract: Initialization data independent of logging curve data values (such as grid definitions and starting depths) are transmitted to a remote terminal where well log curve displays are desired. Data corresponding to magnitudes of successive adjacent points on the curves are then sequentially transmitted as delta values. Each delta value is the difference in magnitude between two adjacent sample points on a given curve. Transmission of redundant and unnecessary information such as integer values of curve samples is thereby eliminated. Large amounts of well log data may then be transferred quickly to remote locations at low data transmission rates associated with conventional telephonic communication links. Cumulative error resulting from reconstructing curve sample magnitudes from delta values is eliminated by a bi-directional transmission error checking scheme.

Abstract: A method for producing a display of acoustic signals received during full waveform acoustic well logging. In a preferred embodiment, the signals received at the individual receiver (or receivers) of the logging tool are stacked along lines of constant acoustic velocity to produce for display a stacked signal. Preferably, the raw signals are weighted prior to the stacking step, to compensate for decreasing amplitude of the acoustic arrival of interest with increasing transmitter to receiver distance. The stacked signals produced may be displayed in various formats, such as on a linear or logarithmic scale of inverse acoustic velocity, or of formation porosity.

Abstract: A method and apparatus allows dynamic data to be recorded in a drill string for later playback at the surface. The system includes a transducer located in a sub in the drill string which provides electrical responses to a analog to digital converter. A timer circuit provides timer pulses to the converter to cause the response to be converted into a digital value for storing in a recorder. The timer pulses are also used to address the memory location. The timer circuit has the ability to provide a variable number of timer pulses at a variable frequency and at variable intervals. A surface timer circuit provides simultaneous timer pulses to a counter to indicate at the surface which memory location is being filled at any given time.

Abstract: An improved method and apparatus for displaying visual indications of subsurface-derived earth measurements. Digital logging measurements are delivered to video circuits for graphic display. The video circuitry includes a cathode ray tube and digital processing circuitry whereby an image is continually scrolled along with depth reference lines in correlation with movement of the sonde through the borehole. A moving visible representation of a preselected portion of the measurement may thus be continuously observed as it is obtained, moving relative to the display to simulate sonde movement within the borehole. A digital memory technique reduces the number of digital co-ordinates required to be stored and time required for visual data and reference line generation and scrolling wherein digital representations of starting co-ordinates are sequentially incremented and displays made in functional response thereto.

Abstract: The apparatus and method of the present invention pertain to visual presentation systems employing scan lines, wherein each scan line is divisible into sets of points respectively corresponding to locations at which well measurements are made. The resulting sets are shaded in accordance with the value of the respective measurements. Harsh transitions between adjacent sets are removed by having a parameter evaluated for each point of the scan line in accordance with (a) the spatial relationship of a subset of points which includes the point to adjacent sets of points; and (b) the well measurement made at the location to which the point corresponds. The parameter value is compared with a randomly or pseudo-randomly generated number, and the point is marked if the result of the comparison satisfies a preselected relationship. The parameter is evaluated and the comparison is made for all other points in the scan line.

Abstract: A borehole logging tool employs an energy transmitter and receiver for scanning a borehole with energy pulses. An orientation pulse is produced each time the tool rotates past a predetermined orientation position. The time period between orientation pulses is measured and divided into a plurality of discrete intervals. Sine and cosine functions are generated for the measured time period having a sine and cosine value corresponding to each of the discrete intervals. The sine and cosine functions are used to produce sweep functions for controlling the outward sweep of the electron beam of a PPI display device so as to produce a circular rotating pattern in which each revolution corresponds in time to a measured time between orientation pulses. The output of the receiver modulates the electron beam sweep to generate a visual display of the azimuthal scan of the borehole.

Abstract: A display system for use with a well logging tool of the type that scans a borehole wall by rotating an acoustical transducer while emitting and receiving acoustic energy. The received acoustic or information signals are received and recorded for later use. In addition, both the amplitude and time-of-flight of the information signals are digitized and passed to a computer that controls a television display and cathode ray tube. The amplitude is displayed on the television screen while the time-of-flight is displayed on the cathode ray tube as a caliper log.

Abstract: An improved well logging system and method is provided for deriving and visibly displaying a recordable representation of a comprehensive lithological profile of the earth materials traversed by a borehole. In a particular form of the invention, all logging measurements are derived in digital form and on the same depth-dependent bases, such that measurements taken during one trip through the borehole may be combined or processed with other logging measurements taken during a different trip through the same borehole of interest, such that all of the measurements may then be processed at one time to derive the various lithological indications sought to be provided.An improved monitoring system and technique is further provided, such that those logging measurements and lithological relationships of interest may also be correlatively displayed on a real-time basis with respect to at least some of the logging measurements from which they are derived.

Abstract: Apparatus and method for recording seismic signals on a logging chart as a function of the depth of a logging sonde within a well bore includes apparatus for analyzing the seismic signals. The method utilizes the recording of information relating to the slope of a seismic signal received from the sonde. A recording trace is made using successive horizontal sweeps with no vertical deflection, and presence of a mark on the recording can indicate a positive slope for the seismic signal, and the absence of a mark can indicate a negative slope. An apparatus of the present invention utilizes this method to record well logging information obtained from seismic signals.

Abstract: A system and method for processing and displaying well-logging data provides direct indications of various lithological characteristics in conjunction with symbolic representatives of formation lithologies. Preselected programming of a two-dimensional symbol matrix into a memory device provides symbol flexibility. Geometric symbol matrices corresponding to different formation characteristics are digitally stored. When a preselected relationship occurs between lithological characteristics, the particular preselected matrix corresponding to the relationship is repetitively retrieved and displayed between the lithological characteristics curves. Because a relatively small digital matrix pattern may be used and repeated, only a small amount of storage is required for each symbol.