Abstract: A method, a system, and an apparatus are described for the data acquisition in the well-logging of a borehole wall during the investigation of formation properties. Data acquisition is conducted by either an adaptive phase compensation processing or a modulus mode processing, both of which use in-phase and out-of-phase current components to obtain current values. Adaptive phase compensation employs a calculation of a phase shift compensation value, which may then be applied to subsequent acquisitions and can be further processed in the generation of an image of the borehole wall.

Abstract: An electromagnetic (EM) data acquisition method for a geological formation may include operating EM measurement devices to determine phase and amplitude data from the geological formation. The EM measurement devices may include at least one first EM measurement device within a borehole in the geological formation, and at least one second EM measurement device at a surface of the geological formation. The method may further include processing the phase data independent from the amplitude data to generate a geological constituent map of the geological formation, and identifying different geological constituents in the geological constituent map based upon the measured amplitude data.

Abstract: Certain embodiments described herein provide an estimate of the magnetic interference incident upon a drilling system using multiple magneticclaim sensors within a downhole portion of the drilling system in a first wellbore. Certain embodiments utilize the magnetic measurements to determine an axial interference resulting from one or more magnetic portions of the downhole portion and to provide an estimate of a relative location of a second wellbore spaced from the first wellbore.

Abstract: Disclosed is an adaptive borehole correction (ABC) technique based on an inversion approach that advantageously corrects shallow laterolog measurements for borehole effects, including determining and accounting for unknown tool eccentricity. The algorithm is based on simplex radial 1-D inversion where at every logging up to four unknowns are determined, namely tool eccentricity, Rt, Rxo, and Lxo. After that a borehole correction methodology is employed wherein the tool response in a borehole with real mud resistivity Rm is modified to a response in the borehole with virtual mud resistivity equal to Rxo.

Abstract: Disclosed is a method for determining calibration factors of an induction tool that includes three receiver coils, each having a distinct orientation. The method includes: placing the induction logging tool in a first position at a first height above a surface of the earth; performing a first set of measurements of conductivity using the receiver coils with the induction logging tool in the first position at the first height; placing the induction logging tool in a second position at a second height above the surface of the earth; performing a second set of measurements of conductivity using the receiver coils with the induction logging tool in the second position at the second height; and determining the calibration factors that correct conductivity measurements performed by the induction logging tool in a borehole penetrating the earth using the first and second sets of measurements.

Abstract: A method for estimating a property of an earth formation penetrated by a borehole includes conveying a drill tubular through the borehole and transmitting a signal into the formation with a transmitter transducer disposed at the drill tubular. The method further includes receiving a first signal with a first receiver transducer having a sensitivity oriented in a first direction and disposed an axial distance from the transmitter transducer and receiving a second signal with a second receiver transducer having a sensitivity oriented in a second direction different from the first direction and disposed an axial distance from the transmitter transducer. The method also includes calculating a corrected signal that corrects for at least one of bending and torsion of the drill tubular between the transmitter transducer and the first and second receiver transducers using the first signal and the second signal and estimating the property using the corrected signal.

Abstract: A method for increasing sensitivity in a measurement of at least one of magnitude and direction of resistivity in a subsurface material, the method including: performing a first set of measurements of resistivity of the subsurface material using a first logging instrument; constructing a model of a background signal using the first set of measurements; calculating a predicted response of a second logging instrument to the model of the background signal; performing a second set of measurements of at least one of magnitude and direction of resistivity of the subsurface material using the second logging instrument; deriving a second logging instrument response from the second set of measurements; and subtracting the predicted response from the second logging instrument response to produce a corrected response that has greater sensitivity than the second logging instrument response.

Abstract: A method for determining movement of a fluid contact in a subsurface reservoir includes measuring azimuthally sensitive resistivity at a first time from within a wellbore penetrating the subsurface reservoir. A first position of the fluid contact with respect to the wellbore is determined using the azimuthally sensitive resistivity measurements. After a selected time, the measuring azimuthally sensitive resistivity from within a wellbore penetrating the subsurface reservoir is repeated. Movement of the fluid contact from the first position is determined using the repeated azimuthally sensitive resistivity measurements.

Abstract: A method for detecting formation resistivity outside of metal casing using time-domain electromagnetic pulse in a borehole, the method including steps of a) providing a borehole large power pulse transmitting source, recording an induced electromotive force ?, and full time digital recording a transmitted waveform and a received signal; b) conducting transmission-reception and superimposing received signals to improve signal to noise ratio; c) calculating corresponding casing response according to known casing parameters and recorded current waveform of the transmitting source to obtain a relative induced electromotive force ??f; d) correcting relative induced electromotive force value; e) carrying out one-dimensional inversion and converting the observation signal into radial variation information of the formation resistivity; f) obtaining a two-dimensional image of the longitudinal and radial resistivity distribution of outer cased formation resistivity for measured well sections; and g) determining residua

Abstract: A method for estimating a fracture aperture in a formation penetrated by a well includes obtaining at least one of a vertical resistivity (Rv) and a horizontal resistivity (Rh) of the formation; obtaining a mud resistivity (Rmud) or a matrix resistivity (Rmatrix); and estimating the fracture aperture. The estimating of the fracture aperture may be performed by solving the following two equations: Rv=Vhf·Rm+(1?Vhf)·Rmatrix and 1/Rh=Vhf·1/Rmud+(1?Vhf)·1/Rmatrix, wherein Vhf is the fracture aperture.

Abstract: Tools, systems, and methods are disclosed for multi-component induction logging with iterative analytical conversion of tool measurements to formation parameters. At least some system embodiments include a logging tool and at least one processor. The logging tool provides transmitter-receiver coupling measurements that include at least diagonal coupling measurements (Hzz, Hxx, and/or Hyy) and cross-coupling measurements (Hxy, Hxz, and Hyz). The processor employs an iterative analytical conversion of the cross-coupling measurements into formation resistive anisotropy and dip information. The processor may further provide one or more logs of the resistive anisotropy and/or dip information.

Abstract: A multi-step electromagnetic inversion method is provided for determining formation resistivity, anisotropy and dip. An electromagnetic logging tool is used to obtain non-directional, anisotropy, and directional (including symmetrized and anti-symmetrized resistivity measurements) in a formation using an electromagnetic logging tool. Bed boundaries of the formation are first identified. A horizontal resistivity profile is obtained using the non-directional resistivity measurements, and a vertical resistivity profile is obtained using the anisotropy resistivity measurements. The vertical resistivity profile is improved using the directional resistivity measurements, while dip values are also obtained via an inversion using the directional resistivity measurements. Then, an inversion for each of vertical resistivity, horizontal resistivity, dip values, and bed boundaries is performed using all of the non-directional, anisotropy, and directional resistivity measurements to obtain a formation model.

Abstract: In electrical resistivity tomography and electrical impedance tomography, interference effects of the metal well casing can be reduced by disposing measurement electrodes in the form of conductive bands around a region of primary insulation on the well casing. Secondary insulation can be provided longitudinally adjacent the primary insulation to further reduce the interference effects. Parameters of the primary and secondary insulation may be determined using finite element methods. The conductive band electrode can connect to a wire of a multi-strand cable using a novel takeout arrangement. Novel measurement methods are also described.

Abstract: A method of processing electromagnetic signal data includes: disposing a downhole tool in a borehole in an earth formation, the downhole tool including at least one electromagnetic transmitter; performing a downhole electromagnetic operation, the operation including transmitting an electromagnetic pulse from the transmitter into the formation and measuring a time domain transient electromagnetic (TEM) signal over a selected time interval following a transmitter turn-off time; transforming the measured time domain TEM signal into a frequency domain TEM signal measured; and applying an inversion technique to the transformed frequency domain TEM signal to estimate one or more formation parameters.

Abstract: An apparatus for measuring formation resistivity in logging while drilling application includes a tool body, a pair of receivers deployed on the tool body including a first receiver and a second receiver, a measuring transmitter deployed on the tool body and at an axial distance from the pair of receivers, and a compensating transmitter deployed on the tool body and positioned substantially at the midpoint of the pair of receivers. The compensating transmitter transmits compensating signals to the pair of receivers and the measuring transmitter transmits measuring signals to the pair of receivers. The pair of receivers measures the amplitudes and phases of the compensating signals and the measuring signals in a sequential order and computes a compensated amplitude ratio and a compensated differential phase accordingly. A corresponding method for measuring formation resistivity is also provided.

Abstract: An apparatus for measuring formation resistivity and dielectric constant used with a logging tool includes a tool pad coupled to the logging tool, a pair of receivers deployed on the tool pad including a first receiver and a second receiver, a measuring transmitter deployed on the tool pad and at an axial distance from the pair of receivers, and a compensating transmitter deployed on the tool pad and positioned substantially at the midpoint of the pair of receivers. The compensating transmitter transmits compensating signals to the pair of receivers and the measuring transmitter transmits measuring signals to the pair of receivers. The pair of receivers measures the amplitudes and phases of the compensating signals and the measuring signals in a sequential order and computes a compensated amplitude ratio and a compensated differential phase accordingly. A corresponding method for measuring formation resistivity and dielectric constant is also provided.

Abstract: A method, a system, and an apparatus are described for the data acquisition in the well-logging of a borehole wall during the investigation of formation properties. Data acquisition is conducted by either an adaptive phase compensation processing or a modulus mode processing, both of which use in-phase and out-of-phase current components to obtain current values. Adaptive phase compensation employs a calculation of a phase shift compensation value, which may then be applied to subsequent acquisitions and can be further processed in the generation of an image of the borehole wall.

Abstract: A method of processing electromagnetic signal data includes: receiving transient electromagnetic (TEM) signal data from a downhole tool disposed in an earth formation, the downhole tool including at least one conductive component; estimating an initial bucking coefficient based on relative positions of the at least two receivers; combining the TEM signal data using the initial bucking coefficient to estimate an initial formation signal; selecting a plurality of bucking coefficient values based on the initial bucking coefficient and estimating a plurality of formation signals, each formation signal corresponding to one of the plurality of bucking coefficients; and selecting an optimal bucking coefficient from one of the initial bucking coefficient and the plurality of bucking coefficients based on the plurality of formation signals, the optimal bucking coefficient providing suppression of parasitic signals due to the at least one conductive component.

Abstract: A method of interpreting petrophysical measurement data include arranging measurements of at least one physical property of formations into a matrix representing the measurements and selecting a range of number of unobserved factors or latent variables for factor analysis. Factor analysis is performed on the measurement matrix and comprises performing factorization of measurements matrix into a number of factors and performing rotation of the factorization results. Whether the factor loadings for each factor have achieved a “simple structure” is determined and either each of the selected number of factors is associated with a physical parameter of the formations, or one is added to the number of factors and factor analysis and rotation are repeated until factor loadings of all factors have achieved “simple structure” such that the each of the number of factors is associated with a physical property of the formations.

Abstract: A method for identifying low resistivity low contrast high temperature high pressure productive subsurface formations rich in acid gases penetrated by a wellbore includes obtaining dielectric permittivity measurements of selected formations adjacent at least part of the wellbore. Nuclear magnetic resonance relaxometry measurements are obtained for the selected formations, the relaxometry measurements being calibrated to identify relaxation times corresponding to acid gases in high humidity at elevated pressure and temperature. Zones are identified for withdrawing formation fluid samples based on the dielectric permittivity and relaxometry measurements.

Abstract: An electromagnetic method for obtaining a dip azimuth angle from downhole electromagnetic measurements includes acquiring electromagnetic measurement data in a subterranean borehole from at least one measurement array. The electromagnetic measurement data is processed by a least squares method to obtain the dip azimuth angle. Related systems and apparatuses are also disclosed herein.

Abstract: A method of inverting induction logging data for evaluating the properties of underground formations surrounding a borehole, the data including induction voltage measurements obtained from a tool placed close to the formations of interest, the method includes: (a) defining a relationship relating the induction voltage to wave number, dielectric permittivity and conductivity; defining a cubic polynomial expansion of the relationship; and solving the cubic polynomial relationship using the voltage measurements to obtain values for conductivity that includes skin-effect correction, and apparent dielectric permittivity; and (b) using the obtained values for conductivity and apparent dielectric permittivity to derive a simulated value of induction voltage; determining the difference between the simulated value of the induction voltage and the measured induction voltage; and iteratively updating the values of conductivity and dielectric permittivity used for the derivation of the simulated value of induction voltag

Abstract: A series of scans is generated for a subsurface and a derivative image is created using the series of subsurface images. One or more tests are performed on the derivative image, and a subsurface object is detected based on the one or more tests. A sensor is configured to generate a series of scans for a subsurface and a processor is coupled to the sensor. The processor is configured to execute stored program instructions that cause the processor to generate a series of images of the subsurface using the series of scans, create a derivative image using the series of subsurface images, perform one or more tests on the derivative image, and detect a subsurface object based on the one or more tests.

Abstract: A method for predicting a pressure window for drilling a borehole in a formation includes: obtaining a pore pressure related data value of the formation using a data acquisition tool; predicting pore pressure uncertainty from the pore pressure related data value of the formation using a processor; estimating uncertainty of a pressure window for drilling fluid using the predicted pore pressure uncertainty using a processor; and applying the estimated uncertainty to the pressure window to provide a modified pressure window using a processor.

Abstract: A system and method for determining formation parameters is provided. The system includes an induction logging tool having a plurality of transmitter coils. The induction logging tool further includes a plurality of receiver coils, each of the receiver coils being spaced apart from the transmitter coils by a predetermined distance and receiving a response signal from the formation. The system includes circuitry coupled to the induction logging tool, the circuitry determining voltages induced in the plurality of receiver coils by the response signal. The circuitry separates real or in-phase portions of the determined voltages from imaginary of ninety degrees out of phase portions of the determined voltages and determines formation parameters using imaginary portions of the measured voltages.

Abstract: Methods and computing systems for processing electromagnetic data are disclosed. In one embodiment, a method is disclosed that includes performing a first controlled source electromagnetic survey at a selected area that includes a reservoir zone; performing additional controlled source electromagnetic surveys at the selected area after the first survey; and inverting measurements from the first survey and the additional surveys to identify at least one resistivity change in the reservoir zone after the first survey, wherein during the inversion, respective measured resistivity values from the first survey and respective measured resistivity values from the additional surveys are constrained to be constant, and correspond to one or more areas disposed in the selected area that are outside of the reservoir zone.

Abstract: A method and apparatus for removing drift from a curve of raw data acquired from a wellbore that intersects a subterranean formation. The raw data curve is filtered to remove DC components, integrating the filtered curve generates a new baseline curve. Adding the new base line curve to the filtered curve yields a corrected curve that is used to extract drift from the raw data curve. The corrected curve is filtered and then subtracted from the raw data curve to produce a drift curve. A data curve, absent any drift, is generated by filtering the drift curve, and subtracting the filtered data curve from the raw data curve.

Abstract: The method of the invention comprises the following steps: positioning a field source (40) at at least one first distance from a target volume (10); positioning a field receiver (50) at at least one second distance from same target volume (10); for each couple of first and second distance, determining a measured signal Smes and a simulated signal Ssim; determining values of physical parameters of same target volume (10) by minimizing a function depending on the measured Smes and simulated signals Ssim. The method of the invention is characterized in that when determining a simulated signal Ssim, specific global reflection coefficients and receiver-receiver functions are introduced in feedback loops.

Abstract: The present disclosure relates to methods and apparatuses for evaluating an earth formation using complex dielectric permittivity. The method may include estimating at least one property of the earth formation using a real part and an imaginary part of complex permittivity at a plurality of frequencies. The at least one property may include one or more of: oil viscosity and surface tension of a water-oil system. The method may include performing dielectric permittivity estimates using an electromagnetic tool in a borehole. The apparatus may include the electromagnetic tool and at least one processor configured to store information obtained by the electromagnetic tool in a memory. The at least one processor may also be configured to estimate at least one property of the earth formation.

Abstract: A technique provides a methodology for improving surveys of subterranean regions. The methodology comprises estimating macro anisotropy and an intrinsic or micro anisotropy of an overburden. A surface electromagnetic survey is conducted, and the data from the survey is inverted based on or including information gained from estimating the macro anisotropy and/or intrinsic anisotropy. A processor system can be used to conduct the inversion with the adjustments for anisotropy to improve the information provided by the survey.

Abstract: A method for estimating at least one formation parameter from a directional resistivity measurement includes computing a plurality of hypothetical directional resistivity values at a corresponding plurality of formation parameter values. The computation makes use of a forward model having at least one analytical expression that relates a directional resistivity measurement to the formation parameter. The analytical expression includes at least one image source term. Comparison of computed directional resistivity values with measured direct resistivity values enables a value of at least one formation parameter to be selected. The method may be implemented on a downhole processor.

Abstract: A method of determining anisotropy in a borehole is disclosed. An array of measurements along the borehole is obtained and a first depth in the borehole is selected. An arbitrary plane oriented with respect to the borehole at the first depth is designated and an anisotropy for the first depth with respect to the arbitrary plane is determined. The arbitrary plane is repositioned at the first depth and an anisotropy for different positions of the arbitrary plane at the first depth is determined. A minimum anisotropy coefficient with respect to the arbitrary plane at the first depth is identified based on anisotropy for different positions of the arbitrary plane. An anisotropy tensor for the first depth is then identified.

Abstract: A method of processing azimuthal measurement data includes: receiving a plurality of data values generated by a rotating measurement tool, the measurement tool including at least one measurement sensor and configured to rotate and measure a signal at each of a plurality of azimuthal orientations; associating each received data value with an azimuthal orientation; selecting one or more data values that provide sufficient information regarding a measured signal, each of the selected data values having an associated azimuthal orientation; disregarding azimuthal orientations associated with one or more data values that provide insufficient information regarding a measured signal; and fitting only the selected data values to a sinusoidal curve.

Abstract: The disclosure relates to an apparatus and a method for well logging as well as a data processing device thereof. Said apparatus for well logging comprises a drill collar body and an array of antennas, wherein said array of antennas comprises at least a pair of transmitting antenna and receiving antenna, said transmitting antenna and receiving antenna are configured for generating a curve of axial forward depth of investigation. By employing the method for well logging according to the present invention, not only the variation of resistivity in the axial forward formation may be measured in real time during the drilling, but also the interfacial characteristics of the axial forward formations having different resistivity may be discriminated during drilling.

Abstract: To update a subterranean model, an initial subterranean model is provided, and based on the initial subterranean model, changes to subterranean parameters are predicted using a reservoir simulator. Electromagnetic data representing characteristics of a subterranean structure is computed according to the predicted changes to the subterranean parameters, and the initial subterranean model is modified based on comparing the computed electromagnetic data with observed electromagnetic data.

Abstract: Various embodiments include apparatus and methods to operate an induction measurement process in a borehole that addresses direct coupling of a signal between sensors of a measuring tool. Apparatus and methods can include a processing unit to generate formation parameters from signals received in the measurement tool. Additional apparatus, systems, and methods are disclosed.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: A Bayesian methodology is described for designing experiments or surveys that are improved by utilizing available prior information to guide the design toward maximally reducing posterior uncertainties in the interpretation of the future experiment. Synthetic geophysical tomography examples are used to illustrate benefits of this approach.

Abstract: A method and apparatus for identifying a ballooning zone in downhole formations. In one embodiment, a method for identifying a ballooning zone in downhole formations includes disposing a drill string in a wellbore. The drill string includes a plurality of wired drill pipes connected end-to-end, and a bottomhole assembly connected to the drill pipes. While circulating drilling fluid through the wellbore, a first resistivity of a formation drilled is measured. While not circulating drilling fluid through the wellbore, a second resistivity of the formation drilled is measured. The first resistivity and the second resistivity are compared. Based on a result of the comparing, a level of ballooning attributable to the formations is identified.

Abstract: An electromagnetic measurement system and related methods are provided. The system includes an electromagnetic source located at a predetermined depth and configured to generate electromagnetic waves in surrounding formations, and a grid of electromagnetic detectors located on a surface of the rock formation and configured to detect the electromagnetic waves generated by the electromagnetic source and reflected by an underground hydrocarbons reservoir. The system also includes a data processing unit configured to process first data and second data related to the electromagnetic waves detected by the grid of electromagnetic detectors, to extract changes of the underground hydrocarbon reservoir, the first data and the second data each being acquired for up to one week, at least two months apart from one another. The electromagnetic source and the grid of electromagnetic detectors are not moved or removed between when the first data was acquired and when the second data was acquired.

Abstract: A method of processing data includes: disposing a downhole tool in a borehole in an earth formation, the downhole tool including a conductive carrier, a transmitter, a first receiver disposed at a first axial distance from the transmitter, and a second receiver disposed at a second axial distance from the transmitter that is less than the first axial distance; performing a downhole electromagnetic operation, the operation including transmitting an electromagnetic (EM) signal from the transmitter into the formation and detecting a first EM response signal by the first receiver and a second EM response signal by the second receiver; applying a linear transformation to the second EM response signal to generate a transformed signal, the linear transformation having parameters associated with a set of data corresponding to a signal representing the conductive carrier; and subtracting the transformed signal from the first EM response signal to generate a corrected EM signal.

Abstract: An apparatus and method for a property ahead of a drill bit in a borehole penetrating a formation. The apparatus may include at least one receiver toroid disposed on a carrier and a transmitter toroid configured to induce an electromagnetic signal in the formation and disposed between the drill bit and the at least one receiver toroid. The apparatus may include at least one processor configured to estimate the property using a signal produced by the at least one receiver. The method may include estimating the property using the signal produced by the at least one receiver toroid. The method may also include one or more of: (i) generating a conductivity curve based on signals from at least one receiver toroid, (ii) validating signals from one receiver toroid based on a conductivity curve of another receiver toroid, and (iii) filtering a receiver toroid signal using lateral resistivity information.

Abstract: To analyze content of a subterranean structure, electric field measurements at plural source-receiver azimuths in a predefined range are received. Total magnetic field measurements are also received at plural source-receiver azimuths in the predefined range. The electric field measurements and the total magnetic field measurements are provided to an analysis module to enable determination of electrical resistivity anisotropy of the subterranean structure.

Abstract: A method to determine one or more borehole corrected formation properties using measurements made using a logging tool disposed in a borehole penetrating an earth formation is disclosed. The measurements are used to determine an apparent conductivity tensor for the formation and, for a set of parameters, a parameter value for each parameter in a subset of the set of parameters. A parameter value for each parameter in the set of parameters not in the subset is provided and a borehole-inclusive modeled conductivity tensor is computed. The apparent conductivity tensor and the borehole-inclusive modeled conductivity tensor are iteratively used to optimize the parameter values, and the optimized parameter values are used to compute an optimized conductivity tensor. A borehole corrected conductivity tensor is computed using the optimized conductivity tensor, and the borehole corrected formation properties are determined using the borehole corrected conductivity tensor and/or the optimized parameter values.

Abstract: Certain embodiments described herein provide an estimate of the magnetic interference incident upon a drilling system using multiple magnetic sensors within a downhole portion of the drilling system in a first wellbore. Certain embodiments utilize the magnetic measurements to determine an axial interference resulting from one or more magnetic portions of the downhole portion and to provide an estimate of a relative location of a second wellbore spaced from the first wellbore.

Abstract: A system determines a volumetric fraction of oil in a formation penetrated by a borehole, the formation comprising an unconventional reservoir. The system includes a carrier configured to be conveyed through the borehole and a geochemical tool disposed at the carrier and configured to determine a mineral makeup of the formation and excess carbon not apportioned to any mineral of the mineral makeup, the excess carbon being associated with kerogen and oil in the formation. An NMR tool disposed at the carrier determines porosity of fluid in the formation, the fluid excluding the kerogen in the formation. A density tool disposed at the carrier determines bulk density of the formation, and a processor determines the volumetric fraction of oil in the formation based on the excess carbon, the porosity of the fluid in the formation, and the bulk density of formation.

Abstract: A computer system and a computer-implemented method for calibrating a reservoir characteristic including a permeability of a rock formation. The method includes inputting a measured product KH of a measured permeability K and a flowing zone thickness H over a plurality of corresponding zones in one or more wells and inputting porosity logs for each measured product KH in each of the plurality of zones obtained from the one or more wells. The method further includes reading a porosity-permeability cloud of data points; calculating, for each zone, a predicted product KH from the porosity log using the porosity-permeability cloud of data points; determining one or more weighting coefficients between the predicted KH and the measured KH corresponding to each zone; and calibrating the measured permeability corresponding to each zone using the one or more weighting coefficients.

Abstract: Logging systems and methods to provide azimuthally-sensitive saturation logs. In some embodiments a processor operates on formation porosity and resistivity measurements from an azimuthally-sensitive logging tool assembly to derive a saturation log having a dependence on tool position and rotation angle, and possibly on radial distance as well. The processor may provide the log to a user via a screen, printer, or some other display mechanism. The logging tool assembly includes at least one tool to measure formation porosity. Suitable tools include a gamma density tool, a neutron density tool, a nuclear magnetic resonance tool, and an acoustic tool. The tool assembly further includes at least one tool to measure formation resistivity. Suitable tools include a laterolog tool, an induction tool, and a propagation resistivity tool. The tool assembly can be a wireline sonde, a tubing-conveyed logging assembly, or a logging while drilling tool assembly.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.