Abstract: A detonation shock wave perforating system for use in perforating subsurface earth formations traversed by a borehole. The system includes a plurality of mechanically serially connected perforating gun sections, each section of which may contain a plurality of shaped charges mounted therein and a length of detonator cord. To provide coupling of the detonation shock wave between housing sections, a booster is coupled to the detonator cord and mounted proximate a shaped charge having its axis of perforation aligned along the longitudinal axis of the gun. Detonation of the shaped charge results in a jet which detonates a quantity of explosive material in the subsequent gun section the detonation of which transfers a detonation shock wave into a detonator cord, thereby detonating any explosive connected thereto. An alternate embodiment provides for coupling of the detonator wave without using a shaped charge unit.

Abstract: A method of determining the location and dimensions of collars present along a section of casing. An inspection instrument is passed through the casing section generating an electromagnetic wave which permeates the casing. The phase shifted electromagnetic wave is detected by a receiver and a data string comprising the degree of phase shift present at each point along the casing section is created. The data string is processed to identify the location of collars present along the casing section. Upon the identification of a collar, a series of pattern recognition interrogations are used to confirm the collar location and to determine the collar's dimensions.

Abstract: In apparatus for investigating earth formations traversed by a borehole, improved methods and apparatus are provided for performing inductive type formation measurements. A transmitter coil of a well logging tool moving through a borehole emits an alternating field into the adjacent earth formation thus inducing eddy currents therein. A voltage in a receiver coil in the tool is sampled at discrete elevations as the tool traverses the borehole and amplified. This voltage is phase detected with respect to the transmitter coil voltage to insure that the measured receiver voltage corresponds to the currents induced in the formation. An average of these voltage measurements is formed. Variations in the magnitude of the average phase-detected voltage are used to discretely control the amplitude of the alternating current induced into the formation.

Abstract: Apparatus for collecting a plurality of samples of fluids in earth formations traversed by a wellbore includes control circuits for supplying power control signals to the subsurface instrument. The control circuits include circuitry for establishing electrical connection to the hydraulic power system of the instrument and after a preselected period of delay supplying power signals to a hydraulic pump motor and/or solenoid valve controls therein. Current is monitored by over-current protection circuitry. In the instance of a current overload, power signals are removed from the hydraulic power system and after a preselected period of delay the control circuits are disconnected from the instrument.

Abstract: A downhole microprocessor controller disposed in a well logging sonde receives and stores one or more preselected tables or series of logging tool commands down loaded from a surface computer through a logging cable telemetry link. Each tool command in a particular table may correspond to a specific function to be performed by a respective logging tool comprising the sonde. All such commands in a given table may be called up by the controller from memory in response to a corresponding sequence command from the surface computer corresponding with the desired table. Upon receipt of such a sequence command, the microprocessor sequentially recalls each of the table's tool commands and relays them in order to the tools.

Abstract: A method of determining the presence of channels in the cement behind a well casing utilizing the temperature profiles of the well. In a first embodiment rate coefficients indicative of the rate of temperature change along a zone of investigation are calculated from the geothermal gradient, flowing temperature profile and at least one shut-in temperature profile. These rate coefficients are plotted versus depth, with inconsistencies in the valves of the rate coefficients being indicative of the presence of channels. In a second embodiment rate coefficients are calculated over a well bonded zone of the well casing and utilized to predict shut-in temperatures along the zone of investigation. Differences in the predicted and actual shut-in temperatures is further indicative of the presence of channels.

Abstract: Method and apparatus for nondestructive inspection of oilfield piping includes first and second elongated nonmagnetic housing members having an elongated magnetic core therebetween. A first coil assembly for emitting a unidirectional flux field is coupled to the core member. Detector shoes are coupled to said core member proximate the first coil assembly and are based into contact with the interior surface of the piping. Second and third coil assemblies are coupled to the core member for emitting unidirectional fields in opposition to the field emitted from the first coil assembly.

Abstract: A method for determining the water or residual oil saturation of subsurface earth formations substantially independent of lithology utilizing electromagnetic energy propagation measurements. The subsurface formations are first logged to obtain base log measurements of the dielectric permitivity of the formations as derived from electromagnetic energy propagation time values. The formations are then injected with a sufficient amount of oil miscible solution containing a surface active agent to displace substantially all the residual fluids from the formations for a radial distance at least equal to the radial zone of investigation. The formations are then injected with a sufficient amount of water to render the zone of investigation substantially 100 percent water saturated. The formations are logged a second time to obtain measurements of the dielectric permittivity of the saturated formations.

Abstract: A generalized computer-based system and method for acquisition of nuclear well logging data. A feature of the present invention is the ability to provide time distribution spectra over the entire interval between source firings, such spectra including the gamma radiation produced from both the inelastic scattering and capture of neutrons from said neutron source. The spectra so generated may be analyzed and processed to derive parameters indicative of formation and borehole conditions, for example, a parameter sensitive to borehole geometry and a parameter sensitive to porosity. Certain parameters may be compared as an indication of the presence of gas in a fluid filled formation. Still further, a quantitative measure of the repeatability of the macroscopic thermal neutron absorption capture cross-section may be derived and used to control the weight of the capture cross-section filter.

Abstract: A well logging instrument for measuring the resistivity of relatively thin formation beds. A well logging instrument includes an elongated body member, serving as a single guard electrode, and a point current emitting measure electrode recessed therein. The instrument is lowered into a borehole and urged into contact with the wall of the borehole. A measure current emanates from the measure electrode into the formation for determining the resistivity thereof.

Abstract: Method and apparatus for use in introducing electromagnetic energy into subsurface earth formations and acquiring measurements relating to propagation of such energy therethrough. A logging tool body includes a plurality of transmitter and receiver antenna assemblies positionable against the borehole wall. Construction of each antenna assembly includes a cavity-backed slot resonated by lumped elements, the slots being oriented generally with their elongate dimension transverse to the tool body. The transmitters and receivers are interconnected, respectively, to a downhole source of electromagnetic energy operating nominally at 200 MHz and to appropriate receiver circuitry. Formation dielectric constants are determined from phase differences and relative amplitude ratios of energy from the formation incident on the receiver antennas.

Abstract: A method and apparatus are provided for permitting an instrumentation package to be repeatedly locked and unlocked at any number of desired depths inside a subsurface production tube for the determination of the shut-in physical conditions at those depths. An instrumentation package is located below a tube packoff tool. The instrumentation package and tube packoff tool combination are lowered into the tube. At the desired depth, a longitudinal force is exerted on the tube packoff tool, causing the tube packoff tool to wedge against the inside of the tube, locking the tube packoff tool at that depth, and creating a seal which isolates the instrumentation package below. The instrumentation package then begins its determination of the shut-in physical conditions inside the tube at that depth and transmits the acquired data to a surface recording and processing facility.

Abstract: A shaped charge perforating unit includes a housing having a cavity formed therein. An explosive charge of high explosive material is retained within the cavity by a liner of non-explosive material. The explosive charge consists of quantities of two explosive materials having different detonation sensitivities.

Abstract: A generalized computer-based system and method for acquisition of nuclear well logging data, including downhole generation of spectral information. A downhole instrument traverses a borehole introducing high energy neutrons into the formation at prescribed depths. Resultant gamma rays are detected and converted into pulses which are amplified and conditioned. For acquiring temporal spectral data, a multi-channel scale section is provided which includes a channel number generator which produces a numerical sequence of memory address codes corresponding to a sequence of adjacent time windows. Each code uniquely defines a start time, whereby the windows collectively comprise the time interval of the desired spectrum. Each time a gamma ray pulse is detected, the memory address generated at that time addresses a corresponding memory location and increments the count value resident therein.

Abstract: A generalized computer-based system and method for acquisition of nuclear well logging data. A feature of the present invention is the ability to provide time distribution spectra over the entire interval between source firings, such spectra including the gamma radiation produced from both the inelastic scattering and capture of neutrons from said neutron source. The spectra so generated may be analyzed and processed to derive parameters indicative of formation and borehole conditions, for example, a parameter sensitive to borehole geometry and a parameter sensitive to porosity. Certain parameters may be compared as an indication of the presence of gas in a fluid filled formation. Still further, a quantitative measure of the repeatability of the macroscopic thermal neutron absorption capture cross-section may be derived and used to control the weight of the capture cross-section filter.

Abstract: Antenna apparatus for use in introducing electromagnetic energy into subsurface earth formations and acquiring measurements relating to propagation of such energy therethrough. Antenna construction includes a resonant cavity-backed slot, the cavity being filled with a fluid. The slot receives an insulator plug serving as a floating piston whereby pressure differentials between the cavity and the surrounding borehole are accommodated. A metallic strap within the cavity grounded at one end to the tool body interconnects at the other end to a matching and tuning feed network. A lumped element resonant circuit behind the slot is thereby formed for either radiating or receiving transmitted or received electromagnetic energy, respectively.

Abstract: A detonation shock wave perforating system for use in perforating subsurface earth formations traversed by a borehole. The system includes a plurality of mechanically serially connected perforating gun sections, each section of which may contain a plurality of shaped charges mounted therein and a length of detonator cord. To provide coupling of the detonation shock wave between housing sections, a booster is coupled to the detonator cord and mounted proximate a shaped charge having its axis of perforation aligned along the longitudinal axis of the gun. Detonation of the shaped charge results in a jet which detonates a quantity of explosive material in the subsequent gun section the detonation of which transfers a detonation shock wave into a detonator cord, thereby detonating any explosive connected thereto. An alternate embodiment provides for coupling of the detonator wave without using a shaped charge unit.

Abstract: A method and system for well logging provide indications of the characteristics of fluid flow behind pipe. An acoustic listening device is positioned within a pipe in proximity to suspected fluid flow behind the pipe. Acoustic energy resulting from the fluid flow is detected and separated into at least two frequency groups or ranges; the first comprising acoustic energy of relatively low frequency and the second comprising acoustic energy of relatively higher frequency. The relative distribution of acoustic energy between the two frequency groups provides an indicator of the nature of the fluid flow behind the pipe.

Abstract: A generalized computer-based system and method for acquisition of nuclear well logging data. A feature of the present invention is the ability to provide time distribution spectra over the entire interval between source firings, such spectra including the gamma radiation produced from both the inelastic scattering and capture of neutrons from said neutron source. The spectra so generated may be analyzed and processed to derive parameters indicative of formation and borehole conditions, for example, a parameter sensitive to borehole geometry and a parameter sensitive to porosity. Certain parameters may be compared as an indication of the presence of gas in a fluid filled formation. Still further, a quantitative measure of the repeatability of the macroscopic thermal neutron absorption capture cross-section may be derived and used to control the weight of the capture cross-section filter.

Abstract: A shaped charge perforating unit includes a housing having a cavity formed therein. An explosive charge of high explosive material is retained within the cavity by a liner of non-explosive material. The exterior of the housing is substantially surrounded by a porous jacket of high strength fiber material.