Abstract: A borehole logging tool such as a wireline logging tool or a logging-while drilling tool includes a tool body; a transmitting antenna located in the body; a pulser for causing the transmitting antenna to transmit an electromagnetic signal; a receiving antenna, located in the body, which includes an array of receiver elements disposed around the longitudinal axis of the tool body; and electronics for measuring the difference in signals detected by pairs of elements in the array. The receiver elements can be linear dipole elements and the electronics for analyzing the signals measures the difference in signals measured by pairs of elements so as to determine the direction of a reflecting structure from the tool.

Abstract: Probe-point placement methods are described. A layout description, a netlist description and a cross-reference description of an IC are retrieved from storage. The data structures associate with each net name a list of polygons. Polygons of a selected net are broken into segments of a specified step size. Each segment is evaluated in accordance with a set of prober rules. Values produced by the prober rules are weighted and combined to obtain a prober score for each segment. The prober score indicates suitability of the corresponding net location for probing. If the best prober score indicates an optimal segment exists for probing, the coordinates of that segment are stored and used to direct a probe to the corresponding location of the IC. If the best prober score indicates no optimal segment exists for probing, each segment of the net is evaluated in accordance with a set of probe-point cutter rules.

Abstract: A gamma ray or x-ray detector for borehole use includes a cadmium zinc telluride crystal having the general formula CD.sub.1-x Zn.sub.x Te, where x represents the zinc fraction of the material and preferably is within the range of 0.05.ltoreq.x.ltoreq.0.95. The noise edge and energy resolution characteristics of the detector may be improved by surface treating the crystal to reduce leakage current. The detector has particular application to bulk density and photoelectric absorption factor logging.

Abstract: A method of determining a physical parameter of geological formations having a borehole passing therethrough by using a sonde lowered down the borehole at the end of a cable and including a source of gamma radiation, a very near detector, a near detector, and a far detector, the method being characterized in that: for each energy window, a model is created characteristic of the response of each detector; a "low resolution" value of the looked-for parameter is determined which, when applied to the model, gives rise to a theoretical measurement that is substantially equal to the "low resolution" real measurement obtained by combining the measurements from all three detectors; the measurements from the two detectors nearest the source are combined to constitute a "high resolution" real measurement; and a "high resolution" value of the parameter is determined which, when applied to the model, gives rise to a theoretical value that is substantially equal to the "high resolution" real measurement, the determination

Abstract: The invention concern a combination well logging device adapted to be moved inside a borehole to measure the properties of geological formations through which the borehole passes.The device according to the invention comprises a series of elongate logging sections mounted end to end, including a first section adapted to be maintained with a generatrix applied against the wall of the borehole, a second section comprising a body and a measurement pad adapted to be spaced radially from the body for application against said wall, a third section adapted to be kept space from said wall, and first and second hinges connecting the second section to the first and third sections respectively in order to allow respective angles of inclination between the second section and the first and third sections.

Abstract: A method of determining a depth correction for a logging tool that is moved, while suspended from a cable, along a well, the method being of the type in which a measurement of tool depth is performed at the surface at successive instants, the tool comprising at least two sensors suitable for measuring a characteristic of the well at each instant said two sensors being offset longitudinally in the displacement direction of the tool. The method comprises, at each of said instants:determining a first value for tool velocity by intrinsic measurement;determining a second value of the velocity by correlation between information received from the two sensors; andcombining the first and second velocity values to determine a depth correction to be applied to the surface depth measurement.

Abstract: Apparatus and methods for determining an indication of a nonlinear property of a formation traversed by a borehole are provided. An acoustic tool is used in a borehole to generate first and second signals of different frequencies. As a result of nonlinearities in the formation, the mixing of the first and second signals results in a third signal having a frequency equal to the difference of the frequencies of the first and second signals. The amplitude of the third signal is measured by a detector, and the indication of nonlinearity of the formation is determined according to a relationship which relates the measured amplitude at the measured frequency to the amplitudes of the first and second signals, the frequency of measurement, the velocity of the measured wave, the distance of the receiver from the source, and a function of the nonlinear and linear parameters of the formation.

Abstract: A modular sonde may be configured in various ways for measurements in open or cased boreholes. The sonde is conveyed on an electric wireline with or without a coiled tubing for conveying hydraulic energy from the surface. Modules common to the configurations include telemetry electronics, orientation, hydraulic energy accumulator, fluid chambers, hydraulic power, pumpout, and flow control. Each configuration has a stress/rheology module suited to the borehole situation. An open-hole sonde configuration has a stress/rheology module with an instrumented, inflatable packer module, an orienting module, and a probe module. A second open-hole sonde configuration has a stress/rheology module with an instrumented straddle-packer assembly. A cased-hole sonde configuration has a gunblock assembly, a gunblock orienting module hydraulics for formation pretest and hydraulics for stressing the formation to obtain data related to formation stress characteristics.

Abstract: A logging-while-drilling apparatus includes a source of exciting radiation, means for illuminating the borehole wall with the radiation and means for detecting radiation returning from the borehole resulting from illumination with the exciting radiation. A bottom hole assembly (BHA) incorporating such apparatus can comprise a drill bit, one or more stabilizers and one or more drill collars and the source and illuminating and detecting means can be located in one of these or distributed therebetween according to requirements. A window can be provided to allow illumination of the borehole and detection of returning radiation.

Abstract: A method of determining the resistivity of an underground formation surrounding a cased borehole including the steps of: a) passing a current along a first pan of the casing and measuring the voltage; b) passing a current along a second part of the casing and measuring the voltage, the second part being spaced from the first part by an intermediate region; c) measuring voltages between the first part of the casing and a point in the intermediate region and between the second part of the casing and the same point; and d) using the measured voltages to derive the resistivity of the formation.

Abstract: An apparatus for electrolyzing fluids is disclosed. The resulting electrolyzed fluids are particularly suited for treating physiological materials such as whole blood, plasma, or cell isolates in order to reduce the effect of harmful microorganisms. A container holds the fluid and a power supply provides a source of electrical current to an anode and a cathode positioned within the container. The anode comprises a base material selected from titanium and niobium. An outer layer of platinum is bonded to the base. The anode comprises a cylindrical shape. The cathode is also connected to the power supply and comprises titanium and has a substantially cylindrical shape. The cathode is positioned concentrically in relation to the anode. The spacing between the cathode and the anode is not greater than a preferred amount. Moreover, the voltage potential between the cathode and the anode is not greater than a preferred amount.

Abstract: A method for measuring multiphase flows in a conduit using series of microwave antennae arranged around the circumference of the conduit so as to transmit microwave energy into, or detect propagated microwave energy in the conduit, the method including the steps of: transmitting microwave energy from each antenna in turn while detecting microwave energy at the non-transmitting antenna and integrating the results from all antennae so as to characterize the flow in the conduit. Apparatus for performing the method includes means for exciting each antenna in turn to transmit microwave energy into the pipe and means for detecting microwave energy at the non-transmitting antennae, and means for integrating the results from all transmitters to characterize the flow in the conduit.

Abstract: Methods and apparatus are provided for determining an indication of a nonlinear property of the formation. A sonic tool is used in a borehole to generate a signal having multiple cycles of a wave of a predetermined frequency. The amplitude of a tube wave resulting from the signal is measured. The measured amplitude is then used to determine an indication of the nonlinearity of the formation according to a relationship which relates the measured amplitude to the amplitude of a second harmonic tube wave which is generated in the borehole by the tube wave of the predetermined frequency due to the nonlinear property of the formation. The indication of nonlinearity may then be utilized to give an indication of the relative consolidation of the formation surrounding the borehole.

Abstract: A method for determining the elemental concentrations in an underground formation by irradiating the formation with neutrons, detecting the .gamma. ray spectrum arising from neutron capture by the formation and analyzing the spectrum to determine elemental concentrations. This method avoids the need for activation measurements or natural radiation measurements and which is made possible by modifying the detected yield of iron (Fe) in the spectrum to compensate for the absence of aluminum (Al) and for the absence of potassium (K) when not measured directly. Apparatus for performing this method can comprise a neutron source, such as a broad energy chemical source, e.g. AmBe, or a pulsed accelerator source, a .gamma. ray detector for detecting capture .gamma. rays and means for analyzing the spectra detected by the detector for determining the elemental concentrations in the formation.

Abstract: A logging tool for use in determining the resistivity of an underground formation surrounding a borehole comprises a mandrel with two transmitters spaced apart thereon, each serving to establish a current in the mandrel and in the underground formation. A series of electrodes are spaced along the body between the transmitters and sensors, located at each electrode, measure radial current flow along a path from the mandrel to the underground formation via a respective electrode. Sensors also provide the axial current flowing along the whole mandrel and at positions corresponding to each electrode. A method of determining the formation resistivity includes the steps of measuring the radial currents R.sub.1 R.sub.2 from the mandrel to the formation via each electrode and obtaining the axial currents M.sub.01 M.sub.02 along the mandrel at each electrode due to each transmitter; measuring the total axial current M.sub.

Abstract: A logging method and apparatus for investigating the geometrical characteristics of a borehole comprises an array of circumferentially spaced apart azimuthal current electrodes (Aaz.sub.i) disposed on a sonde (21), and an annular current electrode (A) longitudinally spaced apart from the array of azimuthal electrodes. In a method of investigating the geometrical characteristics of the borehole, currents (Ic.sub.i) are emitted between the azimuthal electrodes and the annular electrode (A). Monitor electrodes (M, Maz.sub.i) are respectively associated with the current electrodes (A, Aaz.sub.i). The potential differences (Vc.sub.i) between annular monitor electrodes (MAz.sub.i) are detected. In response to the detected potential differences, output signals (Rc.sub.i) are generated indicative of the distances between the sonde and the wall of the borehole in a plurality of directions around the sonde.