Abstract: This disclosure sets out a method for applying a temperature correction to calculations that employ measurements made with scintillation detectors. Temperature measurements are made at or near the scintillation detectors and utilized in corrections employing measurements made with the scintillation detectors to obtain quantities that are relatively independent of temperature.

Abstract: For use in an acoustic logging tool, an apparatus which digitizes simultaneously obtained acoustic signals is set forth in the preferred and illustrated embodiment. The device cooperates with N acoustic receivers in a sonde. After an acoustic pulse is transmitted, data is observed at all N acoustic receivers. This apparatus comprises a multiplexer which is connected to the several receivers. The several input signals are multiplexed, thereafter input to a digital data converter forming a procession of output digital words, and the words are stored in a selected order in a digital data buffer. They are delivered to the surface through a telemetry transmitter at a slower rate than the rate at which the data is created. In addition, a transmitter monitor is included. This provides a signal alternately digitized for a specified interval to enable coordination of the data reduction from the acoustic receivers in contrast with the timing of the transmitted acoustic pulse.

Abstract: In a formation testing apparatus lowered into a well to conduct various tests, an internal hydraulic powered system operates various components. In the present disclosure, an improved valve having metal seats overlayed with an elastomeric material cooperates with valve elements to thereby enhance low power for valve operations. The valve element and mating valve seat cooperate on valve opening or closing to reduce valve power requirements and the forces needed for operation.

Abstract: A through tubing bridge plug is disclosed. In the preferred and illustrated embodiment, a central hollow tube having a passage therein supports the external parts. The central passage terminates top and bottom with openings or passages. At the top end, a sleeve valve mechanism originally pinned in an open position is installed. When the installation is completed, the sleeve valve is closed by a sequence of operations to permanently close the flow path. The device is set and anchored by applying a relative downward force to an external sleeve thereby deploying slips to lock the device in location, additionally deploying an upwardly facing petal basket to receive a charge of sand and cement to form a plug, and also deploying a centralizer.

Abstract: For use in a downhole acoustic logging system including an acoustic transmitter and spaced acoustic receiver, the preferred and illustrated embodiment incorporates a gain control for the receiver system. The automatic gain control (AGC) controls data capture without clipping or fadeout, and provides the digitized value of gain setting to be recorded to assist in data reduction whereby the digitized signal and gain of the system are obtained. The inbound signal is divided into a pressure wave, a shear wave and a fluid wave. The gain function is divided into three gain control regions indentified hereinafeter as the P, S and F regions, and the gain is stepped automatically to provide an output voltage within specified limits. Those limits are observed, thereby operating the gain controlled in the AGC in digital fashion, and the received signal is amplified in a controlled manner, thereby enabling recordal of the wave form without clipping or fadeout while capturing the gain to enable recovery of the data.

Abstract: Earth formations penetrated by a borehole are irradiated with pulses of fast neutrons. The epithermal neutrons resulting from moderation of the fast neutrons are detected in a plurality of time intervals to determine the porosity of the adjacent earth formations independently of lithology. Statistical results are improved by taking the ratio of the count rate during build-up of the epithermal neutron population to the count rate during die-away.

Abstract: An earth formation is irradiated with fast neutrons (18), and the formation porosity is determined by a dual-spaced fast/epithermal neutron measurement in which the fast neutron population is measured at a different source-detector spacing (20) than that used for measuring the epithermal neutron population (40).

Abstract: A system for quickly indicating changes in density of a flow of material using a radiactive source and detector where the count rate indicative of density is processed for sensing significant changes in the density in the flow of material as distinguished from random changes and for producing an indication of such changes. In one aspect of the invention, a time filter is utilized with an RC circuit and diodes to require a count rate indicative of a significant density change before producing an indication. In another aspect of the present invention the count rate is processed with respect to a predetermined formulation to determine the occurrence of a significant density change in a time frame and for producing an indication when such change occurs.

Abstract: Advanced analytic methods and formulas have been developed for 2- and 3- mineral solutions in complex lithology reservoirs. Required logs are density, neutron, acoustic, and photoelectric absorption index (PE curve). On the basis of developed mathematic models of complex reservoirs the limitations and maximum possible errors in the determination of porosities and lithologic compositions are presented for each method. In most cases, the formulas developed are simple enough to be used with programmable calculators.

Abstract: A signal amplifier system for use in a downhole logging system wherein a signal transmitter is mounted in a sonde suspended on a logging cable thousands of feet into a borehole. Variable slew rate amplifiers connected to a differential amplifier are set forth. Preferably, programmable amplifiers having a gain determined by a driving current are used. Two such amplifiers are connected to the input signal, and they are driven by different current sources. The output signals are summed at a differential amplifier. Through the use of different slew rates, the incoming signal is amplified by the two programmable amplifiers and the outputs of the two amplifiers are then subtracted from one another. Signals which pass equally through both programmable amplifiers (due to slew rates which do not cause limiting) thus are subtracted from each other.

Abstract: For use with a wire line supported tool adapted to be run in open hole, a wire line connector to be installed between the wire line and at the top of the tool is set forth. The line moving apparatus of this disclosure preferably incorporates concentric telescoping sleeves with guide slots and cooperative protruding lugs. This apparatus attaches to the top end of a tool which is to be held stationary. This enables the supportive wire line to be continuously moved with stroking motion to thereby prevent pressure differential sticking at key seating the mud cake in the open hole.

Abstract: In a formation tester having a snorkel extending laterally for penetration of a formation, differential sticking may occur. In the preferred embodiment, the snorkel is surrounded by a seal ring and a resilient pad around the snorkel. The present invention includes upper and lower, evenly spaced push-off pistons. They are extendable parallel to the snorkel to push the tool body away from the wall of the borehole. The pistons extend piston rods supporting end located pads to enable breaking of differential sticking on retraction of the snorkel.

Abstract: A method for determining formation porosity, volume of clay content, and mode of distribution in gas, oil, and water bearing shaly sand reservoirs provides solutions regardless of whether gas and oil densities are known or unknown, whether or not there is invasion of borehole fluids into the connate fluids, and whether or not there is dispersed clay only or both dispersed and laminated clays are present.

Abstract: A multi-function compensated spectral natural gamma ray logging method provides for determining formation and borehole characteristics directly from naturally occurring formation radiation. The method, which measures formation lithology in open holes and mean casing thickness in cased wells, incorporates active compensation for differences in borehole conditions when calculating relative elemental formation abundancies or concentrations of potassium (K), uranium (U) and thorium (T).

Abstract: For use with a down hole logging system equipped with a logging cable having two wires therein, the preferred and illustrated embodiment sets forth a system which conducts electrical power and telemetry signals along a two wire logging cable. AC power is generated at the surface for transmission to a power consuming load in the sonde. This AC supply has a specified frequency, there also being data gathering equipment in the sonde which forms an AC telemetry signal transmitted up the two wire logging cable. This disclosure is directed to an improvement in the telemetry drive circuitry which maintains the isolation between power flow and signal flow. The circuitry incorporates FET output transistors, transformer coupled, to provide the necessary output signal and isolation.

Abstract: For use in an acoustic logging tool having a sonde adapted to be lowered in a borehole, an improved acoustic transducer comprising a pyramidal frustrum is disclosed. The preferred embodiment incorporates fifteen sides. Each side mounts a piezoelectric crystal for receiving. Mechanical resonant frequencies of the transducer are outside the receiver band width which is about 25 kHz. The resonant frequencies are above 25 kHz, thereby avoiding primary resonant frequencies within the band width.

Abstract: A method and apparatus for logging downhole earth formations which converts, for a given logging tool geometry, a measurement of the extent of energy degradation of the spectrum of gamma rays emitted from a source in the tool and Compton scattered by the formation back to the tool, into a measurement of the density of the formation.

Abstract: For use with a wireline supporting a tool in a well borehole, length measuring apparatus is disclosed. In the preferred form, the length measuring apparatus comprises a housing around the wireline locus, rollers clamping the wireline, and helix following wheels. The wheels track the helix of the wireline around the wireline, rotating on a bearing assembly, and driving a chain. The chain drives an encoder to record length of the wireline in the well borehole.

Abstract: For use with a tubing conveyed perforating gun assembly, a wireline manipulated electrically actuated detonator assembly traversing the interior of the tubing is described. In the preferred and illustrated embodiment, a wireline connected with a sinker bar supports the detonator assembly having a sinker bar sub terminating in a taper adjacent to a set of deflectable collet fingers comprising a latch assembly. The collet fingers are deflected outwardly by the tapered surface and are forced into an undercut located above a booster and detonating cord affixed to the tubing conveyed perforating gun assembly for firing the perforating guns.

Abstract: The disclosure relates to a well logging method which is capable of providing an indication of salinity and water fraction of the production fluid of a borehole. This indication of borehole parameters may be obtained through the use of a conventional gamma ray logging system that detects gamma rays produced by isotopes created from neutron activation of oxygen, sodium, and chlorine that may be present in the production fluid. A logging sonde is passed twice through a portion of interest in the borehole at two different logging speeds. The fluid velocity relative to the sonde may be determined using these two logging speeds and a displacement distance which reflects the time required for a detector associated with the sonde to reach fluid activated by neutrons produced by the sonde.