Abstract: A multiple stage formation fracturing operation is conducted with separate radioactive tracer elements injected into the well during each stage of the fracturing operation. After completion of the fracturing operation the well is logged using natural gamma ray logging. The resulting signals are sorted into individual channels or energy bands characteristic of each separate radioactive tracer element. The results of the multiple stage fracturing operation are evaluated based on dispersement of the individual tracer elements.

Abstract: Apparatus is provided for assisting a subsurface well logging instrument, perforating tool or wireline service tool in tubing or casing re-entry in deviated boreholes. The apparatus includes a body member, composed of two conjugated halves, rotatably mounted on the well logging cable immediately above the well logging instrument. A pair of wheels are rotatably mounted to the uphole facing portion of the apparatus. These wheel members provide a lifting action upon tubing or casing contact to thereby lift the logging cable off the casing and prevent the logging instrument from engaging in jammed contact with the exposed end of the tubing or casing.

Abstract: A telemetering system provides improved cable utilization and bi-directional digital communication between a logging sonde and surface electronics over a single balanced transmission line of a multi-conductor logging cable, with significant signal crosstalk reductions. Receiver circuitry downhole decodes pulses delivered on the line from a surface logic generator which fire transmitter-receiver pairs of an acoustic logging tool in an order defined by the pulses. A PCM transmitter in the sonde thereafter samples data generated by other logging instruments, encodes this information into digital data frames, and transmits the data on the same line to a surface PCM receiver. Circuitry limits surface and downhole receiver response to PCM transmitter and logic generator pulses, respectively. A center tap of the same transmission line also provides for simultaneous noise-free transmission of sensitive low level signals such as remote surface potential and the like to the sonde.

Abstract: An improved well logging technique is provided for more accurately deriving measurements of sub-surface earth formations, for processing and recording such measurements to record them in reproducible form, and to more informatively display such measurements. Other significant features and aspects of the overall technique include improved methods and apparatus for deriving such measurements in digital form and for merging or combining two or more such measurements in one storage.In a particular embodiment of the invention, the logging sonde is provided with means for forming the logging data into discrete "frames" of data expressed in digital form, and for delivering such frames of data to the surface preferably in response to a command signal which is generated at the surface in correlation with the depth of the sonde in the borehole.

Abstract: A rotary fluid motor with an internal liner has an internal manifold system within the casing and liner which provides not only separations for the fluid involved, but cooling fins and a structural support for the liner. The function of the internal manifold is to provide cooling fins which is important for adequate cooling of the motor during operating.

Abstract: A system for orienting a well casing perforating gun for utilization in wells having multiple tubing strings wherein it is desired to perforate the well casing in a zone other than the deepest production zone of the well and includes a hoist and associated apparatus for moving the perforating apparatus through the well and actuating the perforating gun. The perforating apparatus includes an elongated housing supportable on a cable, rollers on the exterior of the housing to support it on the interior of the well casing and/or tubing, the casing perforating gun, an orienting apparatus operable to orient the perforating gun relative to a string of tubing within the casing, a swivel within the housing to permit rotating motion of the lower portion of the housing relative to an upper portion of the housing, and an eccentric weight below the swivel to assist in positioning and aligning the casing perforating gun to the desired position.

Abstract: An improved well logging technique is provided for more accurately deriving acoustic measurements of sub-surface earth formations. Method and apparatus are described for converting an acoustic signature which can be generated on a depth dependent or time dependent basis, into digital format and subsequently employing special processing techniques to yield parameters such as velocity of the transmitted acoustic energy through earth formations and the amplitude of the received acoustic energy. Processing further allows for the generation of noise immunity signals functionally related to a measured signature parameter and for the generation of amplitude control signals. Additionally, a control signal is generated to optimize transmitter firing rate.

Abstract: A method is disclosed for monitoring the flood front movement during enhanced recovery operations wherein flooding fluids are pumped into a number of injection wells forcing residual oil movement toward a production well. A plurality of monitoring wells located between the injection wells and the producing well are logged to establish base logs functionally related to oil saturation and water salinity. Periodically during the water flood operation, the monitoring wells are relogged to detect changes in oil saturation and water salinity. By comparison of the base logs with the series of later derived logs it is possible to accurately monitor the flood front movement including detecting high-permeability zones and monitoring of the flood front profile.

Abstract: A mud by-pass regulator apparatus is provided to regulate the flow of drilling fluid or mud through the downhole portion of a power supply in a measurement while drilling system. The mud by-pass regulator apparatus includes a valve, valve actuator, and a valve actuator control operable to regulate the flow of drilling fluid through the power supply within predetermined limits. The apparatus automatically causes the drilling fluid to by-pass the power supply under certain conditions to maintain regulation of the drilling fluid through the power supply so that its operation is maintained within required limits of the downhole portion of the measurement while drilling apparatus. Motion of the valve is accomplished by the valve actuator and the valve actuator control which is responsive to the pressure drop across a motive power source in the downhole power supply.

Abstract: A shaped charge unit for well perforating having a outer shell with an internal cavity formed therein. An explosive charge material conforms in exterior shape with the inside surface of the cavity and is retained in place by a conical liner of non-explosive material. The interior shape of the cavity is such that an increased amount of explosive material is provided in a circumferential channel located proximate to the periphery of the base of the conical liner.

Abstract: Circuitry is provided for establishing the points in time at which radiation is detected following neutron bursts in pulsed neutron logging. Means are provided to generate a signal indicative of the average time measurement of a predetermined number of detected pulses within a detection gate interval. A first counter circuit establishes a time position for each detected pulse within the detection interval. The time measurement signal is loaded into a down counter which transfers the individual time to a third accumulator circuit where the times signals for a predetermined number of detected pulses are compiled. The total time signal is averaged by dividing the accumulated value by the predetermined number of processed pulses. The resultant value is used to establish the macroscopic thermal neutron capture cross-section of the formation.

Abstract: A measuring device is provided for measuring the weight applied to a drilling bit or like device in a borehole while the drilling is taking place. The measuring apparatus has a tubular housing adapted to be coupled into a drill string preferably immediately above the drill bit. A transducer is mounted in the tubular housing and measures pressure in a captive fluid chamber within the housing which can be correlated to weight on the measuring apparatus and in turn on the drill bit.

Abstract: An elongated housing of a well logging instrument having a lever latch and positioning mechanism attached to a carriage and a snorkel and barrel assembly. One end of the sensing device is mounted on the carriage and the snorkel is affixed to the opposite end. The latch and positioning mechanism allows the assembly to be moved until the snorkel enters the barrel and retains it in place. The mechanism is then secured in place. The mechanism contains an indicator which is visible if the mechanism is not in position to be secured. Electrical signals are passed from the sensing device, through the snorkel to an electrical connector at the end of the barrel and through a cable to the earth's surface.

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.

Abstract: An improved system and method is provided for obtaining information related to subsurface earth formations. Well-logging data from an input terminal is processed and stored in a memory by a first processor. A second processor retrieves this data from the same memory, and further processes the data, which is then transferred to an output terminal device. The first processor obtains access to memory or the input terminal for delivering or retrieving data during pulses of a first pulse train generated by a clock. The second processor obtains access to the same memory or the output terminal for delivery or retrieval of data during pulses of a second pulse train generated by the clock. Performance of each processor's respective functions is synchronized by storage and retrieval of messages by both processors in the common memory.

Abstract: Improved methods and apparatus are provided for correlatively matching, recording, and displaying, two or more sets of logging data measurements with respect to the borehold depth at which they were generated, and independent of their historical or real-time character. In a particular embodiment of the invention, measurements from each set of data derived or sampled at correlative depths are adjacently displayed in graphical form during a logging operation. The depth offset between the measurements is visually or automatically detected, and in response thereto, the subsequent correlation of other selected measurements and depths at which subsequent measurements are derived are thereby adjusted for further processing, display and recording.

Abstract: A clay content curve, for the borehole under investigation is developed through logging procedures such as a gamma ray log or a spectral gamma ray log. Additionally, compaction trend curves based upon historic logging data are obtained for the geologic area of interest. Information provided by the total porosity trend curve is corrected using a function of the shaliness indicator curve. This correction allows the deviation of an effective porosity log for the reservoir which can be recorded or can be used to edit porosity logs.

Abstract: Electronics circuitry for obtaining measurements of subsurface formation parameters is mounted on an elongated chassis which is removably disposed within a tubular housing. One or more sets of angularly disposed ball rollers are disposed along the length of the chassis. At least one of the ball rollers comprising each set will be of the plunger type, capable of exerting a high force level due to the preloaded compression of a plurality of disk springs. The ball rollers are angularly disposed and operatively set so as to exert restraining force upon the chassis while allowing simple insertion into the housing.

Abstract: An improved well logging method and apparatus is provided for more reliable and accurate detection of corrosion in subsurface well casing. Method and apparatus are described for measuring the density of the flux field established inside the casing due to galvanic current flow longitudinally within the casing. A subsurface instrument housing a plurality of flux gates traverses the interior of the casing measuring the flux density within the casing. As the instrument comes proximate a corrosion location there will be detected a change in flux density due to current flowing from the casing into the formation. The detected change is transmitted to a surface location to provide an indication of the location and depth of corrosion.

Abstract: A method is disclosed for the in situ examination of earth formations penetrated by a borehole to ascertain the optimum location along the length thereof for instituting well stimulation operations or, where the well is cased, the optimum location for perforating the casing. The method utilizes natural gamma ray logging to determine the optimum locations with the natural gamma ray radiation of the earth formation surrounding the borehole measured and the total measurement then separated into potassium-40, uranium, and thorium energy-band signals. A differential value is derived by subtracting the energy-band signal for either potassium or thorium from the energy-band signal for uranium, with the differential thereafter compared to a energy-level standard having a preselected magnitude. The optimum locations for perforating and/or instituting well stimulation operations will be those zones in which the differential exceeds the preselected energy level standard.