Abstract: A logging tool is lowered in a borehole. The tool is positioned so that the transducer is offset from the axis of the borehole. The transducer transmits acoustic energy such that it strikes the borehole wall or casing at an incident angle that directs reflections from the borehole wall away from the transducer and at the same time allows transmission into the surrounding formations or cement in the borehole annulas between the casing and the borehole wall. Reflections of the transmitted acoustic energy from anomalies within the surrounding formations as well as cement in the annulas are received by the transducer.

Abstract: In an acoustic logging system for providing information regarding selected parameters of the wall of a borehole in the earth, and of the rock formation which is adjacent the borehole, in which a single transmit/receive transducer system (T/RTS) mounted on a rotating assembly probes the wall of the borehole in a circular scanning pattern as a function of depth, the improvement which includes at least a second T/RTS mounted on the rotating assembly in known geometrical relation to the first T/RTS, and means to process two or more analog electrical scan signals for transmission over one or more electrical transmission channels in a logging cable. In particular, methods and means are described for the transmission of multiple scan signals, whereby more bottom hole parameters are transmitted, including composite electrical scan signals, in which the early part provides a gated high frequency scan signal and the latter part, the gated flow frequency scan signal, for greater penetration into the rock.

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 A RAM provides storage for a full frame of T.V. raster scan signals, which are being withdrawn from the RAM, to the TV monitor, and back to the RAM.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: In an acoustic logging system for providing information regarding selected parameters of the wall of a borehole in the earth, and of the rock formation which is adjacent the borehole, in which a single transmit/receive transducer system (T/RTS) mounted on a rotating assembly probes the wall of the borehole in a circular scanning pattern as a function of depth, the improvement which includes at least a second T/RTS mounted on the rotating assembly in known geometrical relation to the first T/RTS, and means to utilize in combination the electrical scan signals from the at least two scanning T/RTS.

Abstract: Methods and apparatus are disclosed for measuring a length of logging cable introduced into a borehole, thereby measuring the depth of a logging tool, or sonde, attached to the lower end of the cable. The methods involve producing an electrical signal, which propagates along the cable, and detecting at the mouth of the borehole the time of passage of the initial electrical signal and the time of passage of a subsequent electrical signal reflected or returned upwardly from the lower end of the cable, or, alternatively, the time of arrival of the reflected or returned electrical signal at the upper end of the cable. These times can be determined by means of clocks which are switched on by the passage of the initial electrical signal and switched off by the subsequent electrical signal. Knowing the time intervals and the velocity of propagation of electrical signals in the cable, the length of cable from the mouth of the borehole to the lower end of the cable, and thus the depth of the sonde, is measured.

Abstract: In an acoustic logging system for providing information regarding selected parameters of the wall of a borehole in the earth, and of the rock formation which is adjacent the borehole, in which a single transmit/receive transducer system (T/RTS) mounted on a rotating assembly probes the wall of the borehole in a circular scanning pattern as a function of depth, the improvement which includes at least a second T/RTS mounted on the rotating assembly in known geometrical relation to the first T/RTS, and means to process two or more analog electrical scan signals for transmission over one or more electrical transmission channels in a logging cable. In particular, methods and means are described for transmitting multiple scan signals whereby a higher speed of logging is possible without loss of detail of the logs and without modification of the mechanical system of the logging sonde.

Abstract: A method of core cutting and apparatus operable on a seven conductor wireline logging cable for drilling a hole in the sidewall of a drill hole which comprises an elongted housing with a hydraulically operated backup shoe mounted within the housing for wedging the housing at a selected location in the drill hole and a hydraulic motor with a drilling bit connected thereto for rotation by the hydraulic motor. Hydraulic means are mounted within the housing and are connected to the hydraulic motor for moving the bit into drilling engagement with the sidewall of the drill hole. In one embodiment, a core cutting bit is connected to the motor for obtaining a sample of a subterranean formation at the selected location.

Abstract: An apparatus and method for generating seismic signals are described using a modulated vacuum within a chamber plus a compliant, vibration-isolating means. This compliant, vibration-isolating means provides a seal between the chamber and the earth, and also generally prevents the vibration of the chamber from being transferred to the earth. The seismic signal is transmitted directly to the earth by the changes in absolute air pressure within the chamber (the modulated vacuum). As the vibrations of the chamber are generally out of phase with the force developed by the changes in chamber pressure, the chamber vibrations must, for good efficiency, be isolated from the earth. This arrangement is lightweight and inexpensive, as there is no need for either a special mass to induce the vibrations or a special mass to hold the vibrating mass in contact with the earth's surface.

Abstract: Cableless seismic recorders employ a small, mobile amplifier-recorder in which preferentially the recorder tape contains in digital form both identification information (called header data) and the response of a plurality of seismometers (seismometer group) to a seismic source, the whole arrangement requiring no cable connection between the various recorders and the control truck. Since this system is energized by a battery, it has not been previously possible to use summation techniques, as required, for example, when any repetitive seismic source is employed. Such a system is described here. Low power consumption is obtained by using a plurality of recirculating, dynamic shift registers connected in cascade. Feedback from the output of this cascade register chain under synchronized condition permits the seismometer response to the second use of the source to be additively superimposed upon the stored data from the first use of the source, and so on.

Abstract: Seismometer group recorders amplify and make reproducible recordings of one or more seismometers employed in geophysical prospecting. There is no recording of the various groups at the controller instrument truck, as is common in the prior art. The operator needs assurance prior to collecting data through such recorders that the selectively activated group recorders (always considerably less than the total number placed in the field) are ready for the recording. This disclosure describes means for accomplishing such a status display which identifies those group recorders which have been turned on by the radio transmission system or equivalent, verifying that as to each recorder there is available recording medium, proper switching on of the power source, etc.

Abstract: In seismic group recording, each seismic trace is initially digitally recorded by a small, portable, magnetic recorder placed near the corresponding seismometer recorder group. A large number of such groups and corresponding recorders are placed over an area or along a profile line, and from a control point, only those specific recorders needed for a given set of record traces are turned on at any time by transmitting a set of coded signals over a communications link which is usually a radio link. The bandwidth restrictions of licensed geophysical radio channels can cause difficulty in this communications system from control point to the various seismometer groups. Accordingly, this disclosure covers an improvement in the communication method employed in a seismic group recorder system. U.S. Pat. No. 3,806,864 teaches the employment of audio frequency encoding on a frequency-modulated band-limited channel with a maximum audio frequency of approximately 3 kilohertz.

Abstract: This invention concerns a status alarm for a seismometer group recorder. In using group recorders, the automatic recording feature leaves the field personnel (the user) with minimum confidence that operations are satisfactory, in the absence of a status alarm. An alarm functions when a particular group recorder has been energized and is presumptively ready for operation. The alarm system is actuated only when the major systems within the group recorder are ready to operate. The alarm may be either visual or aural or both.