Abstract: A method of oscillating a pressure in a borehole is provided that includes determining a hydraulic diffusivity, using injection tests, in a borehole, calculating a pressure field using a programmed computer at a proximal distance to the borehole using a first forced oscillation result in a porous media, calculating a flow rate at the proximal distance from the borehole by multiplying a gradient of the pressure field by a measured permeability and dividing by a viscosity of a fluid, computing, using the programmed computer, a volumetrically averaged flow rate by integrating a square of the flow rate over a volume around the borehole, outputting a value of an angular frequency for which the volumetrically-averaged flow rate is maximum, and operating a pump at a second forced oscillation according to the angular frequency on the fluid.

Abstract: A method for performing dual mode imaging of a borehole determines a reference point in a geological formation in response to a resistivity measurement of the formation. The reference point is associated with a feature, such as a fracture, in the formation. A tilt angle of the feature is determined, with respect to the reference point, in response to the received electromagnetic signals from the formation. For example a time-of-flight, ranging operation may be performed or an attenuation and phase change of the received signals may be determined to image the feature.

Abstract: Provided is a method of calculating permeability of a porous medium by using analysis of feature variables of friction flows through the porous medium for laminar and turbulent flows considering a geometric feature and a friction loss feature. A method of calculating permeability of a porous medium, according to an embodiment of the present invention, includes obtaining hydraulic diameters and friction factor-Reynolds number relationships of a plurality of reference porous media, deriving a hydraulic diameter-friction factor-Reynolds number correlation between the hydraulic diameters and the friction factor-Reynolds number relationships, and obtaining permeability of a porous medium to be predicted, by using the hydraulic diameter-friction factor-Reynolds number correlation.

Abstract: A method for estimation of water properties and hydrocarbon properties in a subsurface formation include acquiring a plurality of well log measurements from the subsurface formation. The water properties and the formation properties are parameterized with respect to a selected set of well log measurements. The parameterized water properties, the parameterized formation properties and the well log measurements are graphically displayed to estimate the water properties.

Abstract: A method of oscillating a pressure in a borehole is provided that includes determining a hydraulic diffusivity, using injection tests, in a borehole, calculating a pressure field using an appropriately programmed computer at a proximal distance to the borehole using a first forced oscillation result in a porous media, calculating a flow rate at the proximal distance from the borehole by multiplying a gradient of the pressure field by a measured permeability and dividing by a viscosity of a fluid under test, computing, using the appropriately programmed computer, a volumetrically averaged flow rate by integrating a square of the flow rate over a volume around the borehole, outputting a value of an angular frequency for which the volumetrically-averaged flow rate is maximum, and operating a pump at a second forced oscillation according to the angular frequency on the fluid under test, where a change in permeability around the borehole is provided.

Abstract: A drilling system, method and drilling apparatus for determining a parameter of a formation at a downhole location is disclosed. A member having a longitudinal axis is disposed in a borehole at the downhole location. A first magnetometer and a second magnetometer are disposed at an axial location of the member as separate azimuthal locations around the member and oriented tangential to a circumference of circle in a plane transverse to a longitudinal axis of the member. Magnetic fields resulting from a current flowing longitudinally through the member due to a spontaneous potential in the formation are measured to determine the spontaneous potential. The parameter of the formation is determined from the determined spontaneous potential.

Abstract: Disclosed is an advanced detector system and method using a forward three-dimensional induced polarization method for a TBM (Tunnel Boring Machine) construction tunnel. A narrow detection space of a full-face excavated tunnel is fully used, a controller controls doors of a source and measuring electrode compartment and a shielding electrode compartment to open and controls a corresponding hydraulic delivery device to automatically and quickly arrange a source electrode system, a measuring electrode system and a shielding electrode system. Under the action of a shielding current system, tomography detection supply current is directed ahead of the working face.

Abstract: Disclosed dielectric logging tools and methods employ three or more receive horn antennas positioned between at least two transmit antennas, which can also be horn antennas. The logging tools can operate in the range between 100 MHz and 10 GHz to provide logs of formation permittivity, formation conductivity, standoff distance, and electrical properties of material in the standoff gap. Logs of water-saturated porosity and/or oil movability can be readily derived. The presence of additional receive antennas offers a significantly extended operating range, additional depths of investigation, increased measurement accuracy, and further offers compensation for tool standoff and mudcake effects. In both wireline and logging while drilling embodiments, at least some disclosed dielectric logging tools employ a set of three axially-spaced receive antennas positioned between pairs of axially-spaced transmit antennas.

Abstract: An apparatus for measuring spontaneous potential (SP) of an earth formation includes a downhole tool that is moveable within a borehole by conveyance means. A portion of the conveyance means produces a reference DC potential signal. The tool includes a measurement electrode that produces a potential signal representative of SP of the earth formation. The tool also includes circuitry that measures a differential DC potential signal between the potential signal produced by the measurement electrode and the reference DC potential signal. SP data that characterizes SP of the earth formation is generated based upon the output of such circuitry. In one embodiment for a while-drilling tool, the conveyance means and tool are realized by a drill string with an insulative sleeve that supports the measurement electrode and electrically isolates the measurement electrode from the drill string. Other embodiments for while-drilling tools and tools for tough logging conditions are also described.

Abstract: The invention is concerned with a tool and method for determining a downhole parameter. The tool is located in mud surrounded by a formation and comprising a first electrode spaced at a distance from the formation for measuring a first impedance. There is a second electrode located at a second distance from the formation for measuring a second impedance. There is a processing unit for measuring a difference between the first impedance and the second impedance and wherein the parameter is determined based on the difference.

Abstract: The invention is concerned with a tool and method for imaging a formation through a substantially non-conductive medium. The tool comprises first circuitry for injecting a current into the formation, wherein a complex impedance to the current is measured. Second circuitry for determining a phase angle of an impedance of the non-conductive medium and third circuitry for determining a component of the complex impedance that is orthogonal to the phase angle.

Abstract: Disclosed is an advanced detector system and method using a forward three-dimensional induced polarization method for a TBM (Tunnel Boring Machine) construction tunnel. A narrow detection space of a full-face excavated tunnel is fully used, a controller controls doors of a source and measuring electrode compartment and a shielding electrode compartment to open and controls a corresponding hydraulic delivery device to automatically and quickly arrange a source electrode system, a measuring electrode system and a shielding electrode system. Under the action of a shielding current system, tomography detection supply current is directed ahead of the working face.

Abstract: Apparatuses, methods for manufacturing an apparatus and methods for measuring a fluid resistivity are provided. An apparatus for measuring a fluid resistivity includes a fluid column defining structure, two current injecting electrodes, voltage measurement electrodes, and two additional electrodes. The fluid column defining structure is configured to allow a fluid, whose resistivity is to be measured, to fill a fluid column inside the fluid column defining structure. The two current injecting electrodes are configured to inject a known current into the fluid column. The voltage measurement electrodes are configured to measure a voltage across a measurement column included in the fluid column. The two additional electrodes disposed inside the fluid column defining structure, outside of the positions of the two current injecting electrodes in the longitudinal direction are electrically connected to each other.

Abstract: An apparatus for estimating a property of an earth formation penetrated by a borehole, apparatus including: a carrier configured to be conveyed through the borehole; a transducer disposed at the carrier and configured to transmit and/or receive electromagnetic energy into and/or from the earth formation to estimate the property; wherein the transducer includes a plurality of inductively coupled elements in a series, each element configured to transmit and/or receive electromagnetic energy and at least a first connection to a first element in the plurality and a second connection to a second element in the plurality with at least one of the first element and the second element being disposed between end transducer elements in the series.

Abstract: Disclosed is a method of estimating a property of an earth formation penetrated by a borehole. The method includes conveying a carrier through the borehole and performing a plurality of electrical measurements on the formation using a sensor disposed at the carrier and having a plurality of electrodes disposed in a concentric arrangement wherein a standoff distance between the sensor and a wall of the borehole has an influence on each electrical measurement in the plurality of electrical measurements. The method further includes determining an impedance for each electrical measurement in the plurality of electrical measurements and inputting the determined impedances into an artificial neural network implemented by a processor. The artificial neural network outputs the property wherein the outputted property compensates for the influence of sensor standoff distance on each electrical measurement in the plurality of electrical measurements.

Abstract: In accordance with aspects of the present disclosure, techniques for monitoring subterranean sequestered CO2 are disclosed. Tools for gathering relevant data are disclosed, and techniques for interpreting the resultant data also disclosed. For example, electrodes and micro-gravity sensors may be deployed, and their readings interpreted to detect underground CO2 migration.

Abstract: A method and apparatus for determining the fluid permeability of an earth formation is described. An instrument comprising an acoustic source and acoustic and electrokinetic sensors is located in a borehole at a site of interest. The acoustic source is fired and the resulting variations in pressure and electric field generated are measured and recorded. The Biot equation, and an equation for the streaming potential coupled to fluid displacement terms, is solved using finite element analysis to give an expected pressure waveform and electrokinetic waveform based on estimated earth formation properties. By comparison of the measured waveforms and those calculated from the equations, the actual permeability of the earth formation can be deduced.

Abstract: A steerable or non-steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna. The antenna can also be embodied to be more sensitive to resistivity in a particular azimuthal direction.

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 for determining orientation of an electrically conductive formation proximate an electrically substantially non-conductive formation includes measuring multiaxial electromagnetic induction response within the substantially non-conductive formation using an instrument disposed in a wellbore drilled through the formations. A difference from zero conductivity is determined for each component measurement of the multiaxial electromagnetic induction response. The differences are used to correct the measured response of each component measurement in the electrically conductive response. The corrected component measurements are used to determine the orientation of the conductive formation.

Abstract: An instrument for measuring a property of a subsurface material, the instrument including: a magnetic material surrounding a volume in at least two dimensions; and a receiver adapted for receiving energy related to the property of the subsurface material; wherein the receiver is disposed at an exterior surface of the magnetic material.

Abstract: Apparatuses, methods for manufacturing an apparatus and methods for measuring a fluid resistivity are provided. An apparatus for measuring a fluid resistivity includes a fluid column defining structure, two current injecting electrodes, voltage measurement electrodes, and two additional electrodes. The fluid column defining structure is configured to allow a fluid, whose resistivity is to be measured, to fill a fluid column inside the fluid column defining structure. The two current injecting electrodes are configured to inject a known current into the fluid column. The voltage measurement electrodes are configured to measure a voltage across a measurement column included in the fluid column. The two additional electrodes disposed inside the fluid column defining structure, outside of the positions of the two current injecting electrodes in the longitudinal direction are electrically connected to each other.

Abstract: Methods for imaging geological structures include injecting magnetic materials into the geological structures, placing at least one magnetic probe in a proximity to the geological structures, generating a magnetic field in the geological structures and detecting a magnetic signal. The at least one magnetic probe may be on the surface of the geological structures or reside within the geological structures. The methods also include injecting magnetic materials into the geological structures, placing at least one magnetic detector in the geological structures and measuring a resonant frequency in the at least one magnetic detector. Methods for using magnetic materials in dipole-dipole, dipole-loop and loop-loop transmitter-receiver configurations for geological structure electromagnetic imaging techniques are also disclosed.

Abstract: Disclosed is a method of estimating a property of an earth formation penetrated by a borehole. The method includes conveying a carrier through the borehole and performing a plurality of electrical measurements on the formation using a sensor disposed at the carrier and having a plurality of electrodes disposed in a concentric arrangement wherein a standoff distance between the sensor and a wall of the borehole has an influence on each electrical measurement in the plurality of electrical measurements. The method further includes determining an impedance for each electrical measurement in the plurality of electrical measurements and inputting the determined impedances into an artificial neural network implemented by a processor. The artificial neural network outputs the property wherein the outputted property compensates for the influence of sensor standoff distance on each electrical measurement in the plurality of electrical measurements.

Abstract: A device, method and system for measuring characteristics of a geologic formation using a floating reference signal having a mud chamber, an electrode disposed within the mud chamber, and an electrically conductive plate disposed within the mud chamber, the plate separated from the electrode. An alternating current source is provided on the electrode, whereby an electric field is be maintained between the electrode and the conductive plate. An opening in the mud chamber allows drilling fluids to pass there through.

Abstract: Various disclosed resistivity imaging tools and methods provide a high-resolution electrode configuration for imaging in oil-based imaging in oil-based muds. Some tool embodiments have a sensing surface that comprises: a measurement electrode, a focus electrode surrounding the measurement electrode, and a return electrode surrounding the focus electrode. The sensing surface can be provided on an extendable sensor pad or on the wall-contacting portion of a stabilizer. Some method embodiments include measuring the measurement electrode current while driving a voltage signal between the measurement electrode and the return electrode. The voltage signal may simultaneously or sequentially provide energy at different frequencies. The resistivity measurements are combined with tool position and orientation measurements to form a borehole wall image.

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: 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: 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: An artificial neural network, ANN, and method of training the ANN for inversion of logging tool signals into well logs of formation parameters is disclosed. Properly selected synthetic models of earth formations are used to train the ANN. The models include Oklahoma and chirp type of formations. In each model parameter contrasts of from 10 to 1 to about 100 to 1 are included. Models including maximum and minimum parameter values spanning the operating range of the selected logging tool are included. Parameter contrasts at interfaces are limited to realistic values found in earth formations. The selected models are used to generate synthetic tool signals, which are then used as inputs to the ANN for training. When the ANN coefficients are properly adjusted to produce an output matching the original models, the ANN can be used for inversion of any real signals from the selected logging tool.

Abstract: An electromagnetic well borehole telemetry system for transmitting information between a downhole transceiver, disposed preferably within a borehole assembly in the borehole, and a surface transceiver positioned at or near the surface of the earth. A trigger and cooperating strobe are used to define strobe increments. Synchronous telemetry measurements made during the strobe increments are algebraically summed to identify a synchronous cyclical noise component in a composite electromagnetic telemetry signal. Any non cyclical noise components occurring during the strobe increments algebraically cancel in the algebraic summing operation. The cyclical noise component is then removed from the composite signal thereby increasing the signal to noise ratio of the telemetry system. The system is particularly effective in minimizing electromagnetic noise generated by the rotation of a rotating element such as the rotary table or top drive of a drilling rig.

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: 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 well logging tool apparatus is disclosed for conducting measurements in a borehole environment surrounding a borehole that traverses a subsurface formation. The apparatus includes an elongated conductive mandrel having a longitudinal axis, an antenna array positioned about the mandrel and including a transmitter for transmitting electromagnetic energy into the formation, and a sleeve positioned about the antenna array. The apparatus further includes a first set of electrodes and a second set of electrodes. Each electrode has an outer end that is exposed on the outer surface of the sleeve for conductive contact with an adjacent conductive borehole environment. Further, the first and second sets of electrodes are spaced longitudinally apart such that the transmitter is positioned longitudinally therebetween.

Abstract: A single-dipole sensor for determining an electrical property of an earth formation, includes a pad consisting essentially of a body and at least one small electrode separated from a large electrode by an insulator; wherein an output of the sensor includes a measurement of an electrical signal through the formation for each small electrode. A method for using the sensor is included, as well as a method for providing images of the earth formation.

Abstract: Various systems and methods determine a distance, magnitude, and azimuthal angle describing the location of an anomaly within a geologic formation. For example, a method involves identifying an electrical characteristic (e.g., resistivity or conductivity) at each of several sensors in a measurement-while-drilling (MWD) tool. Based on the electrical characteristic, information identifying a formation property of the anomaly is generated. The information includes at least one magnitude and at least one distance. Information information identifying an azimuthal angle is also generated based upon the electrical characteristic. The azimuthal angle relates a position of the anomalous formation to a position of a first sensor in the MWD tool.

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: 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 well logging tool and method are disclosed comprising a conductive mandrel, an antenna array disposed around the conductive mandrel, wherein the antenna array comprises a plurality of antennas disposed on insulating supports and at least one contact spacer, the at least one contact spacer having at least one conductor channel having a contact assembly disposed therein, a sleeve disposed over the antenna array, wherein the sleeve includes at least one electrode assembly, the at least one electrode and the contact assembly adapted to provide a radially conductive path from an exterior of the well logging tool to the conductive mandrel and wherein the electrode assembly comprises a first conductor exposed to the exterior of the well logging tool and at least one second conductor conductively connected to the first conductor and exposed to an inner surface of the sleeve, wherein at least one of the first conductor or the second conductor being in sealed contact with the sleeve to prevent the passage of fluid th

Abstract: A well logging tool and method are disclosed comprising a conductive mandrel, an antenna array disposed around the conductive mandrel, wherein the antenna array comprises a plurality of antennas disposed on insulating supports and at least one contact spacer, the at least one contact spacer having at least one conductor channel having a contact assembly disposed therein, a sleeve disposed over the antenna array, wherein the sleeve includes at least one electrode assembly, the at least one electrode and the contact assembly adapted to provide a radially conductive path from an exterior of the well logging tool to the conductive mandrel and wherein the electrode assembly comprises a first conductor exposed to the exterior of the well logging tool and at least one second conductor conductively connected to the first conductor and exposed to an inner surface of the sleeve, wherein at least one of the first conductor or the second conductor being in sealed contact with the sleeve to prevent the passage of fluid th

Abstract: A well logging tool includes a conductive mandrel; an antenna array disposed around the conductive mandrel, wherein the antenna array comprises a plurality of antennas disposed on insulating supports and at least one contact spacer, the at least one contact spacer having at least one conductor channel having a contact assembly disposed therein; and a sleeve disposed over the antenna array, wherein the sleeve includes at least one electrode, the at least one electrode and the contact assembly adapted to provide a radially conductive path from an exterior of the well logging tool to the conductive mandrel.

Abstract: An integrated, single collar measurement while-while-drilling tool is presented that comprises formation sensors, directional sensors, pressure sensors, a mud pulse telemetry device, and a turbine-generator power device configured in a single collar housing that is no longer than a standard drill collar. No electrical connections are made across drill collar tool joints. The tool provides high reliability and ease of transportation.

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: A coal mining operation begins by using directional drilling to bore several horizontal shafts through a coal deposit with its natural overburden still intact. Any methane gas permeating the coal deposit is pumped out and preferably sold as natural gas to commercial and residential customers, or used locally in support of mining operations. The methane gas evacuation continues until the concentrations are reduced to safe levels for mining. But before mining begins, ground penetrating radar equipment is lowered into the boreholes for electronic imaging studies of the coal deposit. One borehole is used for a transmitter and another for a receiver. Many measurements are made at a variety of frequencies and equipment positions within the boreholes. Such studies estimate the electrical conductivity of the surrounding material, and thereby give clues where and how much coal is actually deposited.

Abstract: In an electrical measurement apparatus and method for measuring an electrical characteristic of an earth formation, such as in a hole drilled for the exploration for hydrocarbons, a detection portion has an operational amplifier operating in voltage follower mode, with a measurement resistor in the feedback loop. The detection portion will typically include a plurality of sensor elements, and the operational amplifier can be switched between the sensor elements. The apparatus also includes a measurement portion adapted to measure the current flow through the measurement resistor, the calculation portion including an integrator.

Abstract: A method and apparatus for determining properties of rocks surrounding a borehole in which electrokinetic signals are generated in the rocks is disclosed. For example, the signals may be generated by the vibration induced by the drilling of the borehole or by a seismic source emitting continuous pressure waves. The electrokinetic signals generated are detected and the signal amplified and processed to measure the porous rock properties.

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: 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: 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: A method for concurrently gathering acoustic and resistivity data for mapping the texture of the sidewall of a borehole using a single imaging tool. The data are sampled, formatted and merged to provide a single composite image of the borehole sidewall.