Abstract: Logging-while-drilling apparatus and methodologies for measuring streaming potential in an earth formation are provided. The apparatus and methodologies can be utilized to find information relevant to the drilling operations. In particular, since the streaming potential measurement relates directly to fluid flow, the streaming potential measurements can be used to track flow of fluids in the formation. In turn, this information may be used to find information relevant to the drilling operations, such as under-balanced drilling conditions, abnormal formation pressures, open fractures, the permeability of the formation, and formation pressure.

Abstract: Body (22) for measuring the resistivity of a formation (9) surrounding a well (10) equipped with a lining (11), comprising: a body (23) of a probe (22), a set of three primary voltage measurement electrodes (ea, eb, ec), an upper electrode (ea) and a lower electrode (ec) and a central electrode (eb), two electrodes (In1, In2), an upper current injection electrode (In1) and a lower current injection electrode (In2) arranged on each side of the set of primary electrodes, characterized in that it also comprises, two secondary voltage measurement electrodes (24, 26) arranged on each side of the set of primary electrodes (ea, eb, ec), and between the two current injection electrodes (In1, In2), the spacing between a secondary electrode (24, 26) and the closest primary end electrode (ea, ec) being more than 1.5 times the spacing between the primary electrodes (ea, eb, ec).

Abstract: A method for measuring anisotropy in thin-bed formations calls for placing a logging tool into a borehole in the formation and applying current to at least one set of injection electrodes and at least one set of return electrodes to measure resistivity in the formation. Resistivity measurements are used to determine aspects of thin-bed formations exposed in the borehole to the tool. The aspects include the formation azimuth angle (?) and the formation dip angle (?). Typically, the measurements and determinations are completed using apparatus including a computer program product.

Abstract: The invention relates to a method for the extra-corporeal qualitative and/or quantitative recording of neuro-toxic substances in the blood plasma of an individual. According to said method, a system containing neurones or neuronal networks, which have been cultivated on or applied to a micro-electrode array or a neuro-chip, in addition to a device for measuring the electrical activity of at least one or several of said neurones are provided, the neurones are brought into contact with a prepared sample of plasma and the electrical activity of the neurones is measured. The aim of the invention is to develop and improve said method in such a way that it supplies reliable, reproducible results for the recording of neuro-toxic substances in the blood plasma of an individual, in particular in the case of encephalopathic conditions, such as for example hepatic failure, or of coma conditions of various origins.

Abstract: A detector for a marine electromagnetic survey system includes a housing arranged to minimize turbulence when the housing is towed through a body of water, and to minimize motion of the housing in any direction other than the tow direction. The housing includes at least one of an electric field and a magnetic field sensing element associated therewith.

Abstract: A self-tuning resonator for use in a transmitter apparatus for inducing alternating currents in a buried conductor. The resonator is dynamically tuned at frequencies below 500 kHz by exploiting the inherent voltage-variability of net capacitance in multilayer ceramic capacitors. The transmitter apparatus provides improved efficiency and induced output power suitable for use in a man-portable locator system, providing a very high magnetic field output from a physically small battery-powered resonator at frequencies under 500 kHz. The resonator exhibits a very low equivalent series resistance (ESR) and is adaptively returned to a predetermined resonant frequency responsive to any changes in resonance arising from phenomena such as component heating, thereby supporting very high tank circuit currents from battery-powered source to produce very high magnetic flux output.

Abstract: A galvanic resistivity tool with one or more measurement electrodes and guard electrodes, and one or more shielding electrodes. The potential difference between the measurement electrodes and the guard electrodes is controlled to minimize current flow between the measurement electrodes and the shielding electrodes. This provides improved focusing and avoids effects of contact impedance.

Abstract: This disclosure describes a Soil Penetrating Electrode with Conical Taper for use with instrumentation for measurement of the electrical properties of soil in situ. The Electrode shape and configuration solves problems of stable and reliable contact with the soil, repeatable contact area, and ease of use by the operator.

Abstract: Sensor assemblies including transmitter and receiver antennas to respectively transmit or receive electromagnetic energy. The sensor assemblies are disposed in downhole tools adapted for subsurface disposal. The receiver is disposed at a distance less than six inches (15 cm) from the transmitter on the sensor body. The sensor transmitter or receiver includes an antenna with its axis tilted with respect to the axis of the downhole tool. A sensor includes a tri-axial system of antennas. Another sensor includes a cross-dipole antenna system.

Abstract: Earth formations are characterized by using an array of electrodes which can measure streaming potentials in the formation, and by interpreting the data obtained by the electrodes. The electrodes are placed on a wireline tool, a LWD tool, or in a fixed manner about a completed wellbore. The measured streaming potentials are generated by drilling with an overbearing pressure, slitting the mudcake in a borehole, acid injection, or any of various other manners which causes fluid movement. The data obtained is interpreted to locate fractures, measure formation permeability, estimate formation pressure, monitor drilling fluid loss, detect abnormal pressure, etc. Particularly, a streaming potential voltage transient having a double peak profile signifies the presence of a formation fracture.

Abstract: A metal detection circuit that includes a power source and a connection to ground. At least one transmitter circuit is electrically coupled to the power source and ground and a transmit coil is electrically coiled to the transmitter circuit. At least one receiver coil has provided along with an amplifier to be electrically coupled to the receiver coil. An integrator is electrically coupled to the amplifier and a track/hold circuit is electrically to the integrator. A filter is electrically coupled to the track/hold circuit and an output. The circuit provides a high amplitude, low duty cycle excitation pulse, which allows for the sensitivity of a high level excitation signal with the power economy of a much lower energy excitation signal. The receiver circuit collects and conditions the signals resulting from the relatively short duration, large amplitude excitation pulse, and goes in to hold mode during the relatively long charge and idle periods.

Abstract: A current to be applied to a ground is defined as the sum of two sinusoidal waves having first and second frequency components. A signal to be used at the time of synchronous detection is defined as a difference between the sinusoidal waves having the first and second frequency components. As a result, a substance in the ground, and the position and depth of the substance can be specified with high accuracy.

Abstract: A method for locating an object buried in soil in which at least one electromagnetic signal is imparted onto the buried object, thereby generating an electromagnetic field around the buried object. The electromagnetic field as well as at least one electromagnetic property of the soil surrounding the buried object, such as moisture content, temperature and density, is then determined. Data related to the at least one electromagnetic property is transmitted to a data processor in which at least one algorithm is applied to the data, whereby a location of the buried object is determined.

Abstract: A logging-while-drilling tool is adapted for incorporation with a drill string having a longitudinal axis. The drill string is further adapted for drilling a wellbore penetrating a geological formation. The drilling tool includes a tool body having a central axis disposed in parallel relation with the longitudinal axis of the drill string and an external, circumferential surface spaced radially outward from the central axis. The tool also includes a measurement apparatus for measuring resistivity of a borehole fluid in the wellbore. The measurement apparatus has an electrode array including a current emitting electrode disposed on the circumferential surface. The current emitting electrode is adapted to emit current into a target region of the wellbore spaced laterally between the circumferential surface and the walls of the wellbore. Further, a current receiving electrode is disposed on the circumferential surface and spaced apart from the current emitting electrode.

Abstract: The invention provides a support for measurement means for monitoring and/or studying a fluid reservoir (13) through which at least one well (11) passes, said support comprising: a cylindrical tube (2); and a jacket (3) surrounding said cylindrical tube. According to the invention, said jacket (3) has at least one recess (4, 5) for receiving means (6) for measuring a characteristic representative of said reservoir and/or connection means (7) leading to power supply and measurement-processing means (16). The invention also provides a measurement device for monitoring and/or studying a fluid reservoir (13) through which at least one well (11) passes, said device comprising: power supply and measurement processing means (16); means (6) for measuring a characteristic representative of said reservoir, and connection means (7) connecting said measurement means (6) to said power supply and measurement processing means (16).

Abstract: The object of the present invention is to realize a low-invasive underground exploration apparatus, system, and method which are capable of specifying the kind, three-dimensional position, and amount of a substance present in the ground. The underground exploration apparatus, system, and method includes: measuring, at multiple points, a high frequency voltage that appears upon conduction of high frequency current through the ground to obtain measurement results at two or more frequency levels; employing an ground model using the finite element method, the boundary element method, an impedance network, or the like to estimate a substance in the ground by changing unknown quantities of the ground model such as local dielectric constant and electric conductivity so as to make an error between the actual measured value and the calculated value smaller; and displaying input information of the ground model and results of the estimation processing two-dimensionally or three-dimensionally.

Abstract: An apparatus is disclosed for measuring formation resistivity through a conductive pipe in a wellbore. The apparatus includes a sonde adapted to be moved through the wellbore, and a plurality of voltage measurement electrodes are disposed on the sonde at spaced apart locations. At least one current source electrode is disposed on the sonde. All the electrodes are adapted to make electrical contact with the pipe. The apparatus includes a digital voltage measuring circuit controllably coupled to selected ones of the voltage measurement electrodes and digitally controlled current sources.

Abstract: A method and apparatus for minimizing direct coupling between transmitters and receivers on a downhole logging tool are disclosed. One embodiment includes a transmitter, a bucking device, and a plurality of receivers, where signals may be directly coupled from the transmitter into the receivers and signals may be indirectly coupled from the transmitter into the receivers through the formation and borehole environment. The bucking device minimizes the magnitude of the signals that are directly coupled from the transmitter into multiple receivers within the plurality. By varying the current in the bucking device, the bucking device minimizes the magnitude of the directly coupled signal of each receiver in the plurality, and each receiver may utilize a common bucking device.

Abstract: A unique means in interpreting anisotropic reservoirs in thinly laminated earth formations regardless of the hole deviation is provided. A high-resolution micro-resistivity formation measurement is used to estimate in real time at the well site the formation anisotropic electrical parameters oriented around the borehole drilled with a conductive fluid. Estimations of the formation anisotropy or hydrocarbon profile are compared and combined with indicators associated with the formation to provide improved evaluations of hydrocarbon content over conventional methods.

Abstract: An apparatus is disclosed for measuring formation resistivity through a conductive pipe in a wellbore. The apparatus includes a sonde adapted to be moved through the wellbore, and a plurality of voltage measurement electrodes are disposed on the sonde at spaced apart locations. At least one current source electrode is disposed on the sonde. All the electrodes are adapted to make electrical contact with the pipe. The apparatus includes a digital voltage measuring circuit controllably coupled to selected ones of the voltage measurement electrodes.

Abstract: A method for determining the location of a target subterranean structure from within an adjacent borehole is disclosed which uses first and second gravity measurement devices disposed at corresponding first and second positions in the adjacent borehole and a magnetic field measurement device disposed one of the first and second positions. The method includes processing a total local magnetic field, a reference magnetic field, and a local azimuth determined using the gravity measurement devices to determine a portion of the total magnetic field attributable to the subterranean structure multiple points in the adjacent borehole. The location of the subterranean structure is determined using the portion of the total magnetic field attributable thereto. A system adapted to execute the disclosed method and a computer system including computer-readable logic configured to instruct a processor to execute the disclosed method are also provided.

Abstract: The present invention relates to a method of investigating the wall (2) of a borehole in a geological formation by means of two injectors (4, 5) with a potential V being applied between them and in measuring the potential difference ?V between two electrically isolated measurement electrodes (6) situated between the two injectors (4, 5) and spaced apart from the formation by an insulating layer (1), in which the resistivity of the formation is obtained from the measured values of ?V, V and I, with corrections being made for the effects due to the nature and the thickness of the insulating layer (1). In a first variant these corrections are based on a correction factor obtained from curves of K=Rt.I/?V as a function of the impedance V/I of the injector. In a second variant these corrections are obtained by estimating the current IF actually injected into the formation while taking account of leakage current IL, and calculating the resistivity of the formation from the equation (I).

Abstract: An electromagnetic induction logging method is disclosed. The method includes measuring electromagnetic induction response in earth formations surrounding a wellbore. The measuring is performed on an electrically conductive sonde support. The measured response is deconvolved with respect to a response of an instrument not having an electrically conductive sonde support.

Abstract: A method and apparatus for measuring properties of rocks surrounding a borehole comprises a means for generating an electromagnetic signal downhole and detecting the seismic signal generated thereby.

Abstract: A system and method for detecting defects in TFT-array panels is provided that improves defect detection accuracy by adjusting the thresholding parameters used to classify defective pixels when the number of defects reported by a TFT-array testing system exceeds a predetermined critical number. In a preferred embodiment, the thresholding parameters are adjusted until the number of reported defects is less than or equal to the predetermined critical number. The predetermined critical number represents a threshold number for determining if the number of reported defects is abnormally high.

Abstract: The invention relates to apparatus with capacitive electrodes for electrical prospecting in a borehole, the apparatus comprising at least two injection electrodes (16, 18), at least two measurement electrodes (28, 34), and a current generator (22) for applying an electrical current between the two injection electrodes. The current generator (22) delivers alternating current at a frequency of 5 kHz to 100 kHz and at a voltage of less than 1000 volts. At least one of the measurement or injection electrodes (16, 28) is placed in a borehole (12, 14) and presents an outer surface that is cylindrical and electrically conductive. The apparatus further comprises means (24) for measuring the current flowing through said injection electrodes, means (36, 36b) for measuring the potential difference between the measurement electrodes, and means for processing the measured current and potential difference to deduce therefrom the characteristics of the subsoil in which the borehole is situated.

Abstract: Methods and apparatus for making subsurface measurements with reduced or eliminated borehole effects. Antenna and electrode configurations address the undesired axial electric currents that are induced along the borehole when antennas with tilted or transverse axes are used to make electromagnetic measurements. Current and measure electrodes are used in combination with antennas to limit the flow of undesired axial borehole currents. Embodiments use passive, active, or semi-active electrodes to limit the undesired current flow.

Abstract: The invention relates to a method and apparatus for studying the resistivity of a geological formation around a borehole fitted with metal casing. An electric current is applied to the casing so as to cause current to leak into said formation at a given level, and said current is shunted by a feedback circuit in contact with the casing on either side of the measurement level, said circuit being organized to ensure that the current flowing along the casing at said level is less compared with the shunt current, the difference between the voltage drops on the adjacent sections of casing situated on either side of the measurement level is determined, and the leakage current (Ifor) is deduced therefrom.

Abstract: Shifts in rock strata are measured be inserting into a bore hole in the rock a conductive tube in which an insulated conductor runs along the length and the continuity is measured between the conductor and the tube. When conductivity is detected, the shift in the strata amounts to the distance required for the tube wall to break the insulation and create an electrical content between the tube and the conductor.

Abstract: A miniaturized electrical resistivity (ER) probe based on a known current-voltage (I-V) electrode structure, the Wenner array, is designed for local (point) measurement. A pair of voltage measuring electrodes are positioned between a pair of current carrying electrodes. The electrodes are typically about 1 cm long, separated by 1 cm, so the probe is only about 1 inch long. The electrodes are mounted to a rigid tube with electrical wires in the tube and a sand bag may be placed around the electrodes to protect the electrodes. The probes can be positioned in a borehole or on the surface. The electrodes make contact with the surrounding medium. In a dual mode system, individual probes of a plurality of spaced probes can be used to measure local resistance, i.e. point measurements, but the system can select different probes to make interval measurements between probes and between boreholes.

Abstract: Methods and apparatus are disclosed for minimizing or eliminating an undesired axial electric current induced along a subsurface borehole in the process of subsurface measurements with transmitter and/or receiver antennas which are substantially time varying magnetic dipoles with their dipole moments aligned at an angle to the axis of the borehole. Some antennas are disposed within the borehole on instruments having a non-conductive support member. One instrument includes a conductive all-metal body with an antenna adapted for induction frequencies. Antenna shields adapted for controlled current flow are also provided with an all-metal instrument. Methods include providing an alternate path for the current along the instrument body. Another method includes emitting a controlled current to counter the undesired current. Another method corrects for the effect of the current using a superposition technique.

Abstract: A method for determining the liquefaction tendency of a water saturated soil is provided in which a driven or self boring probe with a plurality of expanding and contracting bladders imposes a cyclic shear stress reversal on a body of soil in situ, and from the measurement of pore water pressure, the liquefaction potential of the soil can be quantified. A pore water pressure increase during cyclic shear stress reversals indicates a contractive soil which has the potential to liquefy. The method can also quantify the potential of electro-osmosis in preventing soil liquefaction, by energizing a group of at least three electrodes by a d-c power source during the potential onset of liquefaction, and measure the reduction in pore water pressure during subsequent repeated shear stress reversals imposed on the soil by the device.

Abstract: Methods and apparatus are disclosed for minimizing or eliminating an undesired axial electric current induced along a subsurface borehole in the process of subsurface measurements with transmitter and/or receiver antennas which are substantially time varying magnetic dipoles with their dipole moments aligned at an angle to the axis of the borehole. Some antennas are disposed within the borehole on instruments having a non-conductive support member. One instrument includes a conductive all-metal body with an antenna adapted for induction frequencies. Antenna shields adapted for controlled current flow are also provided with an all-metal instrument. Methods include providing an alternate path for the current along the instrument body. Another method includes emitting a controlled current to counter the undesired current. Another method corrects for the effect of the current using a superposition technique.

Abstract: Disclosed herein are processes for detecting the location of an interface between phases. In one embodiment, the process comprises: introducing a reaction mixture into a vessel wherein the reaction mixture is the product of an at least two phase interfacial reaction, and a difference in densities between at least two of the phases is less than or equal to about 1 g/cc, separating the reaction mixture into the phases with an interface located therebetween, measuring electrical inductance of the reaction mixture at different latitudinal locations; and determining the location of the interface.

Abstract: A real time soil constituent sensor and precision agricultural chemical delivery system may measure simple in situ soil constituents without the aid of externally applied solvents, or such solvents may be utilized intermittently to calibrate the measurements for greater accuracy. A real time complex in situ soil resistivity sensor and prescription agricultural chemical delivery system includes a plurality of ground-engaging tools in association with individual soil electrode arrays which measure complex solute and matrix resistivity levels. Conventional engaging tools may serve as electrodes for impressing a voltage source and serve as a current sink for the purposes of determining complex resistivity values and components thereof in in situ soils. Alternatively, local resistivity measurements in a single tool can also be employed for separation of resistivity cotributions of the soil solute and the matrix.

Abstract: A method and apparatus for low cost, convenient prospecting and surveys of subsurface structures using seismoelectric signals, as well as laboratory analysis of geological samples. The seismoelectric signals come from seismic waves generated by sources which can be applied or natural. The seismoelectric signals are generated with the same velocity and frequency of the generating seismic waves, then induce secondary electromagnetic signals which travel at their own much higher speed. The seismoelectric signals thus may be measured with electrodes or antennas. Electrodes may be disposed within a borehole or on the surface. The method allows use of geophone data, but does not require it. The it source of the seismoelectric signals, being a moving seismic wave front, conveys continuous, whole body information on the structures underground, in much the same way as seismic ware data, but in the form of simpler, easier to capture seismoelectric signals. Reflection and refraction of seismic waves can be ascertained.

Abstract: A method and system for determining the location of a microseismic event is disclosed. An electromagnetic sensor measures the electromagnetic energy which is caused by a microseismic event. Seismic data from the microseismic event is measured and recorded using plurality of ground motion sensors. The time at which microseismic event occurred is estimated based at least in part on the time at which electromagnetic energy caused by the microseismic event is received by the electromagnetic sensor. The location of said source of the microseismic event is determined using the estimated occurrence time and the time at which the seismic energy arrived at the ground motion sensors. A method of triggering a seismic recording device is also disclosed. The electromagnetic energy from a microseismic event is measured and recorded using an electromagnetic sensor. The time at which the microseismic event occurred is estimated based on the measured electromagnetic energy.

Abstract: An apparatus for measuring induced polarization of the ground. The apparatus includes a polarizable contact member configured to transmit a current to the ground. An electrode includes a first conductor and a second conductor. The first conductor is coupled to the polarizable contact member. A non-polarizable contact member is coupled to the second conductor of the electrode and is configured to measure an electrical potential associated with the current.

Abstract: The invention includes an apparatus for determining geo-electric data and the density of a porous material. A resistivity-measuring device applies an electrical current through an electrode array to that is part of a non-electrical conductive test cell that is used to measure the resistivity of the porous material that is the test cell. The test cell is a made of a rigid non-electrically conductive material and is a standard shape and dimension. The material that is the test specimen is compacted into the test cell using a standard technique so that the physical properties of the test specimen my calculated. In addition to making a set of standard physical measurement (material unit density and unit moisture content) the test cell is used to measure electrical properties of the test specimen so that a set of electrical constants can be determined for the material under test.

Abstract: Resistivity mapping apparatus includes a tow mechanism for use by a human operator in moving the mapping apparatus over a surface and measuring the resistivity of soils of the surface. The tow mechanism includes a generally triangular shaped tow ring which is engageable by the operator's battery belt, harness, or pack-frame, the tow ring having two opposing hooks at a vertex of the tow ring for receiving a loop from a tow line. The tow line engages the tow ring and a cable depressor weight which keeps the resistivity mapping apparatus in close proximity to the earth as the apparatus is towed. A communication cable in the tow line preferably comprises an optical fiber which transmits signals from the receiver to a data logger carried by the operator.

Abstract: A method of detecting precursor seismic electromagnetic waveforms and predicting future seismic activity in the form of an earthquake by placing a detector including a dielectric material in contact with the earth. The detector receives at the dielectric material precursor seismic electromagnetic waveforms traveling within the earth emanating from a region of seismic activity. A sensor responsive to the dielectric material senses a series of individual discrete signals imposed by the waveforms at the dielectric material wherein each of the signals has the characteristic of a rise time that is shorter than its fall time. Alternatively, the discrete signals may be a single discrete signal characterized by a plurality of overlapping waveforms. Then predicting based on the series of the signals the occurrence of the earthquake.

Abstract: A method and apparatus for measuring impedance of grounding system wherein a transient electric current is injected at the ground system under test while measuring the a transient ground potential difference, as well as the injected electric current. The ground potential difference is measured with respect to several points on the earth's surface at small distances from the test system. These measurements are processed by computer software which filters noise, corrects voltage and current transducer errors, and estimates the test system ground potential rise with respect to remote earth. Correction algorithms are used to remove irregularities in the frequency response of the voltage and current transducers and analog filters. The filtered and corrected measurements are used to estimate the ground impedance as a function of frequency. For this purpose, a parameter estimation procedure is used which takes into consideration the geometric arrangement of the voltage and current probes.

Abstract: A real time soil constituent sensor and precision agricultural chemical delivery system may measure simple in situ soil constituents without the aid of externally applied solvents, or such solvents may be utilized intermittently to calibrate the measurements for greater accuracy. A real time complex in situ soil resistivity sensor and prescription agricultural chemical delivery system includes a plurality of ground-engaging tools in association with individual soil electrode arrays which measure complex solute and matrix resistivity levels. Conventional ground-engaging tools may serve as electrodes for impressing a voltage source and serve as a current sink for the purposes of determining complex resistivity values and components thereof in in situ soils. Alternatively, local resistivity measurements in a single tool can also be employed for separation of resistivity contributions of the soil solute and the matrix.

Abstract: A method of detecting precursor seismic electromagnetic waveforms and predicting future seismic activity in the form of an earthquake by placing a detector including a dielectric material in contact with the earth. The detector receives at the dielectric material precursor seismic electromagnetic waveforms traveling within the earth emanating from a region of seismic activity. A sensor responsive to the dielectric material senses a series of individual discrete signals imposed by the waveforms at the dielectric material wherein each of the signals has the characteristic of a rise time that is shorter than its fall time. Alternatively, the discrete signals may be a single discrete signal characterized by a plurality of overlapping waveforms. Then predicting based on the series of the signals the occurrence of the earthquake.

Abstract: A method and apparatus for detecting underground liquids is disclosed in which the electrical potential generated by a seismic shock is detected and measured with respect to a base point insulated from the earth.

Abstract: The invention includes a method and device for determining the in-situ density of a porous material. A resistivity measuring device applies an electrical current through an electrode array to measure the resistivity of the porous material. The resistivity measuring device may also be used to measure the resistivity of a pore filling fluid. A formation factor and in-situ density constants of the porous material are determined using empirical methods. In-situ moisture content of the porous material is determined. The above data is applied to a general geophysical in-situ density equation to calculate the in-situ density of the porous material.

Abstract: A method and device for determining the hydraulic conductivity of porous materials is disclosed. The method uses a general permeability equation for calculating the hydraulic conductivity. The resistivity of the porous material is measured when the porous material is at least partially saturated with a pore filling fluid. Other data, such as a formation factor, permeability constants of the porous material, and in situ moisture content of the porous material may also be derived or measured. The geophysical permeability equation is then used to calculate the hydraulic conductivity of the porous material from the measurements and data. Methods are also disclosed which provide an average hydraulic conductivity over a given area. A device for determining hydraulic conductivity of a porous material is disclosed which utilizes a plurality of electrodes for conducting electricity to the porous material. A resistivity meter may be attached between the electrodes for measuring the resistivity.

Abstract: A method for estimating porosity of an earth formation from measurements of acoustic energy traversing the earth formation and from measurements of seismoelectric voltages generated in the formation in response to the acoustic energy. The method includes the steps of measuring the acoustic energy traversing the earth formation and measuring said seismoelectric voltages generated in response to the acoustic energy traversing the formation. A seismoelectric signal is synthesized from the measurements of the acoustic energy using an initial value of the porosity. A difference is determined between the synthesized seismoelectric voltages and the measured seismoelectric voltages. The initial value of porosity is adjusted, and the steps of synthesizing the seismoelectric voltages from the acoustic signal, determining the difference, and adjusting the value of porosity are repeated until the difference drops below a predetermined threshold or the difference reaches a minimum value.

Abstract: Device for measuring soil conductivity is comprised of a frame adapted to be conveyed over a ground surface and plurality of soil engaging coulters insulated from each other and insulatively mounted to this frame. This device also includes means for passing a current between a first pair of coulters through the soil and means for measuring this current. It further comprises means for measuring the resulting voltage between a second pair of coulters. This device for measuring soil conductivity also is comprised of electrical contact members which provide consistent electrical contact from the coulter to the means for measuring current and voltage. An electrical signal received by a coulter travels to a mounting flange and then to a dust cap. The dust cap passes this electrical signal to the spindle by way of a spring-loaded plunger. This electrical signal travels from the fixed spindle to the means for measuring current and voltage.

Abstract: An apparatus for measuring the vertical component of the gradient of the electrical field of the soil surface includes two electrodes. Each electrode includes a capacitor with a semiconductor layer.