Abstract: An electrical resistivity tomography prospecting system based on random distribution of electrodes is provided. The system comprises a central console and a plurality of data collection units. The central console and the data collection units are connected via wireless communication. The data collection units comprises a collection station and two electrodes connected via a cable. The electrodes may be randomly arranged based on the grounding condition. The GPS equipped on the electrode may provide the location information of the measurement point. The collection station is controlled by the central console, and may perform in two work modes: current supply measurement or electrical potential measurement. The data collection is parallel. Sequentially selecting one collection unit for current supplying, while the rest of collection units work for potential measurement.

Abstract: Methods and systems for determining subterranean fracture closure are disclosed herein. The methods can include electrically energizing a casing of a wellbore that extends from a surface of the earth into a subterranean formation having a fracture that is at least partially filled with an electrically conductive proppant and measuring a first electric field response at the surface or in an adjacent wellbore at a first time interval to provide a first field measurement. The methods can also include measuring a second electric field response at the surface or in the adjacent wellbore at a second time interval to provide a second field measurement and determining an increase in closure pressure on the electrically conductive proppant from a difference between the first and second field measurements.

Abstract: In some embodiments, a method of approximating or determining at least one dimension of at least one underground geological feature in a zone of interest proximate to a well bore includes generating an electric field in the zone of interest while the well bore and geological feature at least partially contain conductive fluid. At least two sensing electrodes are provided in the well bore and configured to detect differences therebetween in electric potential caused by at least one target object in the zone of interest and provide data relating thereto to at least one data processing system. The data processing system(s) approximates or determines the dimension(s) of the geological feature(s) based at least partially upon data provided by the sensing electrodes.

Abstract: A method of approximating or determining at least one dimension or other characteristic of at least one underground geological feature in a zone of interest proximate to a well bore includes generating an electric field in the zone of interest. At least two sensing electrodes are provided in the well bore and configured to detect differences therebetween in electric potential caused by at least one target object in the zone of interest. Proppant containing signal generating devices (SGD) is delivered into the geological feature(s). The SGD generate a detectable signal in response to at least one downhole condition or property. At least one receiver receives the detectable signals and provides data relating thereto. At least one dimension or other characteristic of the geological feature is approximated or determined based at least partially upon data provided by the sensing electrodes and receiver(s).

Abstract: An apparatus for measuring permittivity of a sample. The apparatus includes: a sample chamber including a sealed space portion in which a sample to be measured is put; a pressure adjusting unit for varying pressure by applying water pressure to the space portion of the sample chamber; a permittivity sensor for measuring permittivity of the sample and disposed outside the sample chamber; measurement conducting wires including conductors, installed to contact the sample and connected to the permittivity sensor by using electric wires; and a data logger for storing data relating to permittivity that is measured by the permittivity sensor.

Abstract: A method for determining spatial distribution of fluid injected into a subsurface rock formation includes injecting the fluid into the rock formation. The fluid includes therein electrically conductive solid particles dispersed in an electrolyte. An electromagnetic response of the formation is measured. The measured electromagnetic response is used to determine spatial distribution of the injected fluid.

Abstract: Determining an electrical property of a formation fluid. At least some of the illustrative embodiments are methods comprising drawing formation fluids into a tool within a borehole, applying a swept frequency electric field to the formation fluids by way of a first winding, inducing a current flow in a second winding based on the swept frequency electric field, and determining a property of the formation fluids based, at least in part, on the current flow in the second winding.

Abstract: System for remote measuring a physical variable comprising an RF transceiver arranged for transmitting an RF signal and for receiving a reflection signal derived from the transmitted signal. An RF transponder comprises a dielectric material having a dielectric property which is dependent on the physical variable according to a first function. The dielectric material is exposed to the physical variable to be measured. The transponder is arranged to receive the signal transmitted by the transceiver and to reflect a reflection signal, or the second and/or higher harmonics of it, which is dependent on the actual dielectric property. Processing means are provided for comparing the signal transmitted by the transceiver and the reflection signal received from the transponder and for converting the comparison result, e.g. the phase shift, into a value which is representative for the physical variable to be measured. The transponder may be e.g. a patch antenna.

Abstract: In some embodiments, apparatus useful for determining at least one dimension of at least one geological feature of an earthen formation from a subterranean well bore includes at least two electric current transmitting electrodes and at least two sensing electrodes disposed in the well bore. The electric current transmitting electrodes are configured to create an electric field and the sensing electrodes are configured to detect perturbations in the electric field created by at least one target object.

Abstract: A transmission system in a downhole component comprises a plurality of data transmission elements. A coaxial cable having an inner conductor and an outer conductor is disposed within a passage in the downhole component such that at least one capacitor is disposed in the passage and having a first terminal coupled to the inner conductor and a second terminal coupled to the outer conductor. Preferably the transmission element comprises an electrically conducting coil. Preferably, within the passage a connector is adapted to electrically connect the inner conductor of the coaxial cable and the lead wire. The coaxial capacitor may be disposed between and in electrically communication with the connector and the passage. In another embodiment a connector is adapted to electrical connect a first and a second portion of the inner conductor of the coaxial cable and a coaxial capacitor is in electrical communication with the connector and the passage.

Abstract: A method for characterization of a formation that includes inducing fluid motion in a formation while making electronic measurements.

Abstract: Method for removing air wave noise from shallow water controlled source electromagnetic survey data, using only the measured data and conductivity values for sea water (140) and air. The method is a calculation performed numerically on CSEM data and resulting in an estimate of those data that would have been acquired had the water layer extended infinitely upward from the seafloor. No properties of the sub-sea sediments are used. Synthetic electromagnetic field data are generated for (a) an all water model (141) and (b) an air-water model (146-147) of the survey region. These simulated results are then used to calculate (148-150) electromagnetic field values corresponding to a water-sediment model with water replacing the air half space, which represent measured data adjusted to remove air wave noise.

Abstract: The methods of evaluating a geometry of a hydraulic fracture in a rock formation penetrated by a borehole comprises the steps of measuring the values of electric or magnetic fields, or both electric and magnetic fields generated due to the electrokinetic effect by the flow of an electrolyte-based fracturing fluid from the borehole into the fracture and from the fracture into the formation or by the reverse flow of the fluid from the rock formation and from the fracture into the borehole and determining the geometry of the fracture from the measured values. The methods may provide for varying the injection pressure, varying the value of the electrokinetic coupling coefficient of the fracturing fluid or applying at least one pressure pulse of a given magnitude to the fracturing fluid.

Abstract: A method for characterization of a formation that includes inducing fluid motion in a formation while making electronic measurements.

Abstract: The cubic equations of state (CEOS) relate pressure, temperature and molar volume of a mixture. The deviation of the physical properties of a mixture from ideality is expressed by the compressibility factor. The compressibility factor is calculated from the CEOS. There is described a solution to the CEOS which provides a continuous solution for compressibility factors over the entire range of operating conditions. This solution avoids the non-unique roots, trivial roots and singularities that are present in the prior art solutions of the CEOS.

Abstract: Methods are disclosed employing seismic waves having infrasonic frequencies in the range of about 0.1–20 Hz for generating electromagnetic waves of similar infrasonic frequency in hydrocarbon bearing subterranean formations located at depths up to about 5000 meters, said electromagnetic waves having sufficient voltage amplitudes for detection at the earth's surface. Also disclosed are seismic sources capable of generating infrasonic seismic waves of sufficient amplitude for generating electromagnetic waves in hydrocarbon bearing formations at depths up to 5000 meters, said electromagnetic waves having voltage amplitudes sufficient for detection at the earth's surface.

Abstract: The present invention relates to the processes and devices for assessing the permeability of a rock medium 1 containing a fluid 2 in its interstices 3. The device and the process according to the invention are characterized essentially in that a given magnetic field is applied to the interstitial fluid 2 located in the rock medium 1, the variation in pressure of the interstitial fluid 2 resulting from the application of the magnetic field is measured, and the permeability of the rock medium is determined as a function of the value of the variation in pressure of the interstitial fluid.

Abstract: A method and apparatus for measuring the properties such as permeability of the rock surrounding a borehole in which a directional seismic or sonic signal is generated downhole and propagated into the surrounding formation to generate an electrokinetic signal and the focus of the seismic signal is moved in three dimensions in the surrounding rock by physically moving the source or by having two seismic sources which generate oscillating seismic signals at different frequencies and the focus of the seismic signal is varied by wave interference or wave interaction.

Abstract: A sea-floor electromagnetic measurement device for obtaining underwater measurements of earth formations including a central structure and arms attached to the central structure so that they can pivot relative to the central structure. An electrode is attached to the end of each of the arms or to the central structure, and/or magnetometers are attached to the arms.

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: A method and apparatus for measuring the properties, such as permeability, of the rock surrounding a metal cased borehole by generating a seismic or sonic shock downhole within the borehole which is propagated into the surrounding formation where it generates an electrokinetic signal which is detected by measuring the potential between at least two space apart electrodes in contact with the casing.

Abstract: Apparatus and method for measuring the properties of rocks such as permeability, porosity and fluid properties downhole around a borehole (3) in which a seismic source (6) which radiates a seismic signal substantially radially within the borehole is lowered down the borehole (3) and the electrical signal generated by the seismic signal within the surrounding rock is detected by detectors (4, 5) mounted above and below the seismic source (6) so that signals are received from substantially all radial directions. Preferably a continuous wave signal is generated and the signal detected whilst the apparatus (1) is raised or lowered. The apparatus (1) gives a much better and more accurate measurement than previous methods.

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: The porosity and permeability of a geological formation (2) are determined on the basis of an electrofiltering phenomenon by exploiting the existence of non-linear electrofiltering phenomena. One or two pressure generators (11 ) are used to propagate a pressure wave in the formation. Electrodes (14, 15) applied against the wall of the formation pick up the electric response of the formation. The detection of a resonance frequency or a phase shift corresponding to an extremum of the electric response of the formation makes it possible to calculate the porosity or permeability of the formation or find their values from charts.

Abstract: A method and the apparatus for in situ analysis of a rock formation that already contains fluid in its interstices an excitation device is provided for imparting motion to the fluid relative to the rock formation and the magnetic fields created by the relative motion of the fluid in the rock formation measured. The permeability of the rock formation are deduced from the measurement. The measurement system is particularly applicable to in situ measurement of the permeability of rocks, e.g. down an oil well.

Abstract: Process and apparatus for determination of permeability of porous media and thickness of layered porous media by measurement at finite frequency of streaming potential and electro-osmotic induced voltage due to applied finite frequency pressure oscillations and alternating current, respectively. The distance between application and measurement of the alternating signals at a finite frequency is small compared to the wave length. A plurality of spaced measurement electrodes provides measurement of the penetration depth of applied pressure oscillations for determination of thickness of porous layers and to largely remove the effect due to mudcake on a borehole in streaming potential measurements.

Abstract: This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen.

Abstract: Process and apparatus for determination of permeability of porous media by measurement at finite frequency of streaming potential and electro-osmotic induced voltage and pressure due to applied finite frequency pressure oscillations and alternating current, respectively. The inter-electrode distance between points of application and measurement of the alternating signals at a finite frequency is small compared to the wavelength of the pressure oscillations and alternating current voltage.

Abstract: A method for time lapse electric logging in a cased hole in which electrodes are implanted in the casing or the hole is completed with a gravel packed non conductive, perforated liner that allows an open hole logging tool to be used for time-lapse logging. Thereafter, the implemented electrodes or a self-potential (SP) logging tool are used to monitor a steam-flooding EOR method by detecting two-phase flow with time lapse logging. A potential drop between the surface and zones of interest is measured with electrodes installed in a non-conductive casing or the SP logging tool.

Abstract: A method and apparatus are disclosed for determining hydraulic properties of formations surrounding a borehole. In one embodiment, trial values of hydraulic properties such as vertical and horizontal permeability are selected and used to obtain computed formation pressure responses that are compared to measured pressure responses taken at a source and two observation probe positions. Trial values can then be modified to bring the computed pressure responses closer to the measured ones. An improved technique is also disclosed for obtaining the computed pressure responses.

Abstract: A heading detecting apparatus is attached to a moving object and includes a geomagnetic field sensor for detecting the direction of the earth's magnetic field in terms of orthogonal first and second signals and a computing circuit responsive to orthogonal first and second electric signals from the geomagnetic field sensor. In the computing circuit, when any one of the orthogonal first and second electric signals from the geomagnetic field sensor is a predetermined value, the value of the other electric signal is detected so that in accordance with the detected value an offset value is computed and stored, and the electric signals from the geomagnetic field sensor is corrected in accordance with the offset values.

Abstract: Method and apparatus for investigating earth formations according to the present invention include positioning an opening of a fluid reservoir in contact with the surface of an earth formation to be investigated and injecting the fluid at high pressures through the opening into the formation to cause a transient electrokinetic potential to form in the formation. The transient streaming potentials generated are detected by appropriate electrodes, and the outputs of the electrodes, representative of the generated potentials, are then processed to determine a characteristic response time of these streaming potentials. Thereafter, from a knowledge of the characteristic response time of the detected streaming potentials a measurement of the permeability of the formation is derived.