Abstract: A logging tool includes a tool body; a simple transmitter comprising a single antenna disposed on the tool body; four simple receivers, each comprising a single antenna, disposed on the tool body and spaced apart from the simple transmitter to form four arrays; and an electronic module for controlling operation of the four arrays, wherein the simple transmitter is configured to generate a magnetic field having a transverse component, wherein each of the four simple receivers is sensitive to the magnetic field generated by the simple transmitter, and at least one of the four simple receivers is sensitive to the transverse component of the magnetic field generated by the simple transmitter, and wherein the four arrays are configured to provide measurements at at least three depths of investigation.

Abstract: A method for producing borehole-compensated values from non-borehole-compensated measurement signals taken with a logging device in a borehole in earth formations, includes the following steps: producing a database that includes a multiplicity of data points, each data point representing a combination of formation parameters and borehole parameters, database input vectors representing multi-dimensional non-borehole-compensated model measurement values respectively associated with the data points, and database output vectors representing multi-dimensional borehole-compensated model measurement values respectively associated with the data points; deriving a multi-dimensional measurement signal vector from measurement signals taken with the logging device in the borehole; and interpolating the measurement signal vector using the database to obtain an interpolated output vector representative of borehole-compensated measurement signals.

Abstract: A method of producing images of formations surrounding a borehole, comprises: obtaining values of a first parameter in the borehole as a function of depth and azimuth at a first resolution; obtaining values of a second parameter in the borehole as a function of depth only at a second resolution; establishing a relationship between the first and second parameters at a matched resolution; using the relationship to derive values of the second parameter as a function of depth and azimuth; and producing an image of the second parameter as a function of depth and azimuth using the derived values of the second parameter.

Abstract: A method is discussed for obtaining resistivity values in a horizontal or highly-deviated wellbore penetrating an anisotropic formation layer. Multi-component data is obtained from the formation layer. An initial value of horizontal and vertical resistivity can be determined by using a whole space model and assuming an isotropic layer. Revised values of the vertical and horizontal resistivities are obtained through a first and second inversion process. A first inversion is performed on the horizontal resistivity, holding a value of vertical resistivity constant. A second inversion is performed on the vertical resistivity, holding a value of horizontal resistivity constant. These inversions are iterated until a desired convergence is achieved.

Abstract: A method and system of operating an electromagnetic resistivity tool wherein at least one transmitting antenna of the tool is selectively operable at three or more resonant frequencies for better resistivity profiling of a formation.

Abstract: An induction logging tool is used on a MWD bottom hole assembly. Due to the finite, nonzero, conductivity of the mandrel, conventional multi frequency focusing (MFF) does not work. A correction is made to the induction logging data to give measurements simulating a perfectly conducting mandrel. MFF can then be applied to the corrected data to give formation resistivities.

Abstract: A method for determining a sonde error in a logging tool comprising a transverse array includes obtaining a first measurement using the transverse array while the logging tool is at a first height from ground in a selected orientation; obtaining a second measurement using the transverse array while the logging tool is at a second height from the ground in the selected orientation; deriving a difference measurement from the first measurement and the second measurement; determining a background signal using the difference measurement and a predetermined function, wherein the predetermined function relates earth signals in a plurality of signals obtained at the second height to a plurality of difference signals between signals obtained at the first height and the second height at a plurality of formation conductivities; and determining the sonde error by subtracting the background signal from the second measurement.

Abstract: A method is discussed of obtaining a parameter of interest of an earth formation, typically a formation resistivity or a distance to a bed boundary, in conditions where an induction tool is using having a body with finite, non-zero conductivity. The method substantially removes the effects of the conductivity of the tool from the signal received from the earth formation. A Taylor series expansion in one half of odd integer powers of time is used to represent the received signal. At least one leading term of the Taylor series expansion can be subtracted from the second signal. A filtering operation is applied to the second signal to remove the terms most dominated by pipe effects. Typical filtering operations can be a differential filtering operation or an integral filtering operation.

Abstract: A system and method of correcting skin effect of conductivity measurements made by electromagnetic induction well logging instruments. A limited number of measurements using different frequencies may be used. The skin effect correction system and method is capable of processing a complex signal waveform but only requires the in-phase signal measurements which are then corrected for the skin effect value and the geometric factors of the apparent conductivity measurements, thus making the corrected measurements suitable for advanced processing with modern array-type induction logging tools.

Abstract: Method and apparatus are provided for adjusting electromagnetic well logging data for effects of frequency dispersion. In exemplary embodiments, a model is provided for estimating an electrical property of an earth formation as a function of frequency. The model is derived, for each particular volume of interest, based on measured data obtained by employing a plurality of interrogation frequencies. Measured data may include electrical properties of the volume of interest such as conductivity and dielectric constant. The model predicts the measurements expected to be obtained by a tool employing a selected interrogation frequency, including frequencies for which no measured data are available. In one embodiment, the model may be used to adjust measured data for effects of frequency dispersion to correspond to a selected interrogation frequency, allowing the adjusted data to be more effectively correlated to logging data obtained by a different type of tool employing a different interrogation frequency.

Abstract: The present invention provides a method of combining various types of data and software in order to arrive at a composite graphical representation of a construction site, including surface and subsurface features. A 2-D or 3-D graph of subsurface contoured surfaces is created. A 3-D wire-frame model of surface and subsurface features is created. Aerial photographs of the site can be incorporated and the aerial photographs contoured surfaces and wire-frame model are to produce a complete Visual Reduction Modeling Language (VRML) model of both surface and subsurface features. The VRML model allows the user to identify and visualize a relationship between sub-surface features and above ground features.

Abstract: Process for the location of the position of the interface (5) between two fluids (f1, f2) each contained in a zone (7-1, 7-2) of a reservoir (4) in which: a) a reference transient flow condition that produces a reference pressure difference (?Pref(t)), is initiated in a reservoir (4) that comprises at least one pressure sensor (8) located within one of the zones (Z1), b) later an effective transient flow condition that produces a pressure wave which propagates within the reservoir (4) producing an effective pressure difference (?Pu1?(t)) is initiated, c) the pressure differences (?Pref(t)), (?Pu1(t)) are compared, d) a point in time (?1) that represents the instant when the pressure wave reaches the interface (5) between the two fluids (f1, f2) is determined, the distance (L1) between the interface (5) and the pressure sensor (8) is calculated. The operations b) to d) are repeated in order to monitor movement of the boundary. Application in the petroleum industry.

Abstract: A method for surveying a borehole is provided. The method includes providing a tool having a magnetic field measurement device disposed thereon and positioning the tool in a borehole. Magnetic interference vectors are determined at at least two positions in the borehole by comparing the measured magnetic fields at those positions with a known magnetic field of the earth. The magnetic interference vectors indicate a direction to a target subterranean structure. Various embodiments of the invention compare the directions to the target subterranean structure with a historical survey thereof, so as to determine a distance between the borehole and the subterranean structure and an azimuth of the borehole. The surveying methodology of this invention may advantageously improve borehole surveying data obtained, for example, in relief well and/or well twinning drilling applications.

Abstract: System and method for borehole compensation. The method includes simultaneously transmitting at least two modulated signals from one or more transmitters; receiving the at least two modulated signals by at least one receiver; and processing the received at least two modulated signals to determine a phase difference and an amplitude attenuation of the transmitted modulated signals, the processing providing borehole compensated data.

Abstract: Techniques for determining a formation property by simplifying various two-geological-layer or multi-geological-layer models into a multi-electrical-layer model. A volume fraction of a layer in a multi-electrical-layer model is determined for an anisotropic region (sliding window) of the formation. The multi-electrical-layer electrical model includes a relative-lower-resistivity layer and a relative-higher-resistivity layer. A high-resolution resistivity measurement is used in the determination and resistivities for the relative-lower-resistivity layer and for the relative-higher-resistivity layer based on the volume fraction and bulk resistivity measure ments of the anisotropic region are determined. The formation property is based on the volume fraction, the resistivity of the relative-lower-resistivity layer, the resistivity of the relative-higher-resistivity layer, a total porosity of the anisotropic region, and bulk resistivity measurements of the region.

Abstract: A method is disclosed for real-time (well-site) resistivity anisotropy determination using array lateral logs or any other unfocused, lateral-type measurements, and array induction logs or any other focused, induction-type measurements. Near-vertical wells with a deviation angle of less than 30 degrees are considered. Since with a lateral log, at each logging depth the injected current has both horizontal and vertical components, the data contains information related to both horizontal (Rh) and vertical (Rv) resistivities. With array induction tool, the induced current in near-vertical wells has only a horizontal component, and the induction data contain information related to Rh only. Having those two data sets acquired in the same well, it is possible to instantly estimate the formation resistivity anisotropy using square of a ratio between borehole and invasion corrected lateral and induction focused logs.

Abstract: A method for processing magnetotelluric signals to identify subterranean deposits is provided for. The methods comprise obtaining magnetotelluric data from an area of interest. The magnetotelluric data comprises the amplitude of magnetotelluric signals recorded over time at one or more defined locations in the area of interest. The data for each location then is filtered through a set of frequency filters. The frequency filters correspond to subterranean depths over a range of interest. Amplitude peaks in the filtered data then are identified and analyzed to determine a value correlated to the resistance of the earth at each frequency and location. The resistance values are indicative of the presence or absence of deposits at the corresponding subterranean depth.

Abstract: A system and method for controlling operation of a drilling rig having a control management system, comprises programming the control system with at least one resource module, the at least one resource module having at least one operating model having at least one set of programmed operating rules related to at least one set of operating parameters. In addition, the system and method provide an authenticating hierarchical access to at least one user to the at least one resource module.

Abstract: A compression scheme for reducing the amount of data that must be transmitted uplink from a formation test while drilling apparatus. Periodic samples are taken within the formation test apparatus and prior to transmitting data uplink, the samples are analyzed to generate curve fit parameters that define a curve that most closely fits the sampled data. A minimal set a data points, time variables, and curve fit parameters are transmitted to the surface where the transmitted data is used to reconstruct the formation pressure test curve. A quality of fit value is also transmitted with the minimal data set as an indication of the quality of the fit between the reconstructed data and the actually sampled data points.

Abstract: An apparatus and a method for recording the magnetic induction tensor induced in an earth formation are provided. The apparatus includes a magnetic induction device having at least three mutually orthogonal transmitter dipoles and at least three mutually orthogonal receiver dipoles that are direct-coupled, and at least three mutually orthogonal receiver dipoles that are cross-coupled. The method includes using the apparatus to sample the magnetic induction tensor components at a point. Further, samples may be taken at regularly spaced intervals using the magnetic induction device, moving the triaxial logging unit so that each transmitter and each receiver sequentially occupy the same point, repeating these steps until each transmitter and receiver array have sequentially occupied all desired points, and combining the magnetic induction tensor components to form the magnetic induction tensor. These components are useful in inferring water saturation and estimating hydrocarbon volumes in petroleum reservoirs.

Abstract: The invention relates to an object-oriented method for simulating a property of at least one fluid in a fluid-containing physical system in which the physical system is represented by a multiplicity of volumetric cells and a multiplicity of connections between cells. The method uses cell-group objects and connection-group objects in the simulation. The invention can optionally comprise additional objects such as an object containing the entire model of the simulation and another object containing a portion of the entire model.

Abstract: A method for determining formation resistivity anisotropy in a wellbore environment. The method of the present invention effectively extends the dynamic range of the existing well logging service of the multi-component induction tool, allowing the use of this service in wells drilled with conductive WBM systems. A sequential inversion processing of galvanic array lateral log HDLL/MLL data or DLL/MLL and also multi-component induction log (3DEXSM) data is used. The formation resistivity structure of the near wellbore environment is determined using the galvanic measurements of the array lateral log tool.

Abstract: The invention relates to techniques for locating and determining the orientation of a fracture in an earth formation. Systems and methods for detecting a fracture in an earth formation using a propagation tool include producing electromagnetic fields using a TMD transmitter in the tool; measuring corresponding voltage signals detected with one or more TMD receivers in the tool; determining harmonics from the measured signal responses by shifting the responses (e.g. by 90 degrees) and performing an addition or subtraction using the shifted response. In some embodiments, the second harmonic is processed to determine the fracture orientation.

Abstract: A wireline logging sonde for sensing fluid properties in a bore hole. The sonde has a main body and a plurality of sensor capsules mounted peripherally to the main body on fingers. A sensor element is located in each sensor capsule. The sensor elements receive power by inductive coupling from the main body and transmit data signals at radio frequencies back to the main body.

Abstract: This invention is directed to a downhole method and apparatus for simultaneously determining the horizontal resistivity, vertical resistivity, and relative dip angle for anisotropic earth formations. The present invention accomplishes this objective by using an antenna configuration in which a transmitter antenna and a receiver antenna are oriented in non-parallel planes such that the vertical resistivity and the relative dip angle are decoupled. Preferably, either the transmitter or the receiver is mounted in a conventional orientation in a first plane that is normal to the tool axis, and the other antenna is mounted in a second plane that is not parallel to the first plane. This invention also relates to a method and apparatus for steering a downhole tool during a drilling operation in order to maintain the borehole within a desired earth formation.

Abstract: A method for performing region growing in a data volume that accounts for noise in the data on a probabilistic basis. The data volume is divided into discrete cells, and a probability distribution for each cell's datum value is calculated. Each probability distribution is randomly sampled to generate one probabilistic, noise-free realization for the data volume, and region growing is performed using selected criteria. The process is repeated for different realizations until sufficient statistics are accumulated to estimate the probable size and connectivity of objects discovered.

Abstract: An induction logging tool is used on a MWD bottom hole assembly. Due to the finite, nonzero, conductivity of the mandrel, conventional multi frequency focusing (MFF) does not work. A correction is made to the induction logging data to give measurements simulating a perfectly conducting mandrel. MFF can then be applied to the corrected data to give formation resistivities.

Abstract: Method and apparatus are provided for adjusting electromagnetic well logging data for effects of frequency dispersion. In exemplary embodiments, a model is provided for estimating an electrical property of an earth formation as a function of frequency. The model is derived, for each particular volume of interest, based on measured data obtained by employing a plurality of interrogation frequencies. Measured data may include electrical properties of the volume of interest such as conductivity and dielectric constant. The model predicts the measurements expected to be obtained by a tool employing a selected interrogation frequency, including frequencies for which no measured data are available. In one embodiment, the model may be used to adjust measured data for effects of frequency dispersion to correspond to a selected interrogation frequency, allowing the adjusted data to be more effectively correlated to logging data obtained by a different type of tool employing a different interrogation frequency.

Abstract: A nonlinear iterative deconvolution method and system. In one embodiment, the system comprises a data acquisition module, a storage module, and a processing module. The data acquisition module obtains logging data from measurements made by a sensor tool moving through a borehole, and stores the logging data in the storage module. The processing module processes the logging data to determine a formation model by iteratively updating a set of formation model values which correspond to a set of positions along the borehole. The iterative updating includes (i) calculating an error value; and (ii) applying a linearizing factor to the error value. The iterative updating may be expressible as a weighted sum of a current formation model value with a product of the error value and the linearizing factor. The iterative updating may continue until an adequate match between the logging data and a calculated tool response is achieved.

Abstract: Data are acquired using multi-array logging tool in a borehole having an angle of inclination to a normal to the bedding plane of earth formations. The multi-array measurements are filtered using angle dependent filters to give a filtered curve corresponding to a target one of the multi-array measurements using angle dependent filters. Correlation coefficients are determined for a set of possible dip angles and a relative dip angle is estimated from the correlation coefficients. This dip angle estimate together with bed boundaries obtained from the multi-array measurements are used for inverting multi-component measurements alone or jointly with multi-array measurements to refine the relative dip angle interpretation and give horizontal and vertical formation resistivity.

Abstract: A method for determining a formation profile surrounding a well bore includes receiving field log data for the formation and generating a Jacobian matrix responsive to the provided field log data. A quasi-Newton update is used to update the Jacobian matrix for each necessary iteration until a generated formation profile converges with the received field log data.

Abstract: Detecting in an earth formation a boundary between first and second formation regions having different resistivities, wherein the first formation region is traversed by a wellbore, using a logging tool provided with a number of electrodes including a monitoring electrode, the method having: a) selecting a location of the logging tool in the wellbore; b) assuming a position of the boundary relative to the selected location, selecting outside the wellbore a target point relative to the selected location, and selecting a target value for a selected parameter in the target point; c) assuming a model wherein the logging tool in the wellbore is surrounded by a homogeneous formation having the resistivity of the first formation region, and determining how two of the electrodes have to be energized in order that in the target point the selected parameter has the target value; d) selecting a monitoring parameter at the monitoring electrode; e) placing the logging tool at the selected location in the wellbore; f) de

Abstract: The population distribution analyzing apparatus is provided with the area setting unit which sets an area in which population distribution of a plurality of users respectively carrying a portable terminal therewith is to be analyzed; the positional information acquiring unit which acquires respective positional information of each portable terminal, and the analyzing unit which analyzes the population distribution of the users in the set area on the basis of the acquired positional information.

Abstract: Apparatus for measuring the resistivity of a formation surrounding a borehole having a conductive casing comprises a tool body; first and second current injectors spaced apart on the tool body for injecting current into the casing; and an insulating body portion disposed between the current injectors, at least three ring electrodes being mounted on the insulating body portion between the current injectors.

Abstract: A method for surveying a borehole is provided. The method includes providing a tool having a magnetic field measurement device disposed thereon and positioning the tool in a borehole. Magnetic interference vectors are determined at at least two positions in the borehole by comparing the measured magnetic fields at those positions with a known magnetic field of the earth. The magnetic interference vectors indicate a direction to a target subterranean structure. Various embodiments of the invention compare the directions to the target subterranean structure with a historical survey thereof, so as to determine a distance between the borehole and the subterranean structure and an azimuth of the borehole. The surveying methodology of this invention may advantageously improve borehole surveying data obtained, for example, in relief well and/or well twinning drilling applications.

Abstract: There is disclosed herein a method of enhancing the vertical resolution of an induction tool, in a manner that may advantageously also reduce undesirable borehole and “negative resistivity” effects. In one embodiment, the method comprises: a) obtaining a vertical magnetic dipole (VMD) response signal from a transmitter-receiver array of antenna elements having magnetic dipoles oriented parallel to a tool axis; b) obtaining a horizontal magnetic dipole (HMD) response signal from a transmitter-receiver array of elements having magnetic dipoles oriented perpendicular to the tool axis; and c) combining the VMD and HMD response signals to obtain a combination response signal. When the relative weights of the VMD and HMD response signals are set as described herein, the combination response signal (and any log calculated therefrom) has a narrow, substantially rectilinear, vertical measurement profile. Further, the combination response signal is relatively insensitive to borehole effects.

Abstract: The invention is a method of determining horizontal and vertical resistivity in an anisotropic formation using a combination of orientable triaxial and array antennae conveyed downhole. Measurements are taken at various azimuthal angles about a measuring device at a given depth. Values at each azimuthal orientation can be fit to a curve to yield information on the surrounding formation. Multiple measurements at a given depth and azimuthal orientation can be weighted to obtain an average value. Values from the curve fitting process are used in subsequent inversion processing and reduce the uncertainty of the inversion processing result. Utilization of a three dimensional geometry enables a unique resolution of the orientation of the principle axis of anisotropy, and consequently of horizontal and vertical resistivity, and dip.

Abstract: A visualization application will generate a Virtual Core representing a compilation of any formation property data, the compilation being a 2 and 1/2 D representation of any formation property. The compilation is generated by creating, in response to an integrated formation evaluation in 1D, a 2 and 1/2 D representation of each 1D formation property in the 1D formation evaluation, when the 1D property can be related to the 2 and 1/2 D physical magnitude combining the 2 and 1/2 D physical magnitude image with the 1D facies log thereby generating a 2 and 1/2 D facies image. The Software will also generate a Virtual Plug representing an average estimate of all formation properties over a prescribed surface or volume in the vicinity of a selection made on the compilation (i.e., on the Virtual Core). When an interaction with the Virtual Core occurs, all results generated by those interactions will be restored.

Abstract: Method and apparatus are provided for adjusting electromagnetic well logging data for effects of frequency dispersion. In exemplary embodiments, a model is provided for estimating an electrical property of an earth formation as a function of frequency. The model is derived, for each particular volume of interest, based on measured data obtained by employing a plurality of interrogation frequencies. Measured data may include electrical properties of the volume of interest such as conductivity and dielectric constant. The model predicts the measurements expected to be obtained by a tool employing a selected interrogation frequency, including frequencies for which no measured data are available. In one embodiment, the model may be used to adjust measured data for effects of frequency dispersion to correspond to a selected interrogation frequency, allowing the adjusted data to be more effectively correlated to logging data obtained by a different type of tool employing a different interrogation frequency.

Abstract: A system and related method for obtaining electromagnetic resistivity logs of a formation having fixed depths of investigation that differ from the actual depths of investigation for the tool. The system and related method comprises calculating actual invaded zone and formation resistivities, and then using least-squares curve fitting techniques to find a function that models the relationship between the physical spacing of the transmitters and the depths of investigation. Using the function, it is possible to find a transmitter-to-receive spacing that, though not actually wed, would give the desired depth of investigation. This transmitter-to-receiver spacing is then used in combination with a second function, determined using least-squares curve fitting methods, which models the relationship between the transmitter-to-receiver physical spacing and the measured resistivity to obtain the resistivity reading at a fixed depth of investigation.

Abstract: A visualization application will generate a Virtual Core representing a compilation of any formation property data, the compilation being a 2 and ½ D representation of any formation property. The compilation is generated by creating, in response to an integrated formation evaluation in 1D, a 2 and ½ D representation of each 1D formation property in the 1D formation evaluation, when the 1D property can be related to the 2 and ½ D physical magnitude combining the 2 and ½ D physical magnitude image with the 1D facies log thereby generating a 2 and ½ D facies image. The Software will also generate a Virtual Plug representing an average estimate of all formation properties over a prescribed surface or volume in the vicinity of a selection made on the compilation (i.e., on the Virtual Core). When an interaction with the Virtual Core occurs, all results generated by those interactions will be restored.

Abstract: An improved induction tool for formation resistivity evaluations. The tool provides electromagnetic transmitters and sensors suitable for transmitting and receiving magnetic fields in radial directions that are orthogonal to the tool's longitudinal axis with minimal susceptibility to errors associated with parasitic eddy currents induced in the metal components surrounding the transmitter and receiver coils.

Abstract: The invention relates to techniques for locating and determining the orientation of a fracture in an earth formation. Systems and methods for detecting a fracture in an earth formation using a propagation tool include producing electromagnetic fields using a TMD transmitter in the tool; measuring corresponding voltage signals detected with one or more TMD receivers in the tool; determining harmonics from the measured signal responses by shifting the responses (e.g. by 90 degrees) and performing an addition or subtraction using the shifted response. In some embodiments, the second harmonic is processed to determine the fracture orientation.

Abstract: A coil arrangement and method of collecting and processing data in induction logging of wells is disclosed. The coil arrangement includes three essentially identical coils made of elliptical conductive loops lying in a plane tilted from the axis of the logging tool. Each coil is centered on the same point in space. Data are preferably collected by using the coil arrangement for both transmitter and receiver, and transmitting at three closely-spaced frequencies, one from each of the transmitter coils. The transmitted signals are received and recorded, at which time they are operated on mathematically to create rotation of an after-the-fact virtual sonde for measuring desired earth formation properties.

Abstract: Induction and other resistivity well logging tools determine formation conductivity at various depths but these measurements contain pronounced errors when the tool is proximate to an inclined underground bed boundary. A method to correct tool measurements includes calculating an expected tool response at a relative dip angle of zero degree and at a particular depth based on an earth model of the underground formation. An expected tool response at the known dip is then calculated. Comparing the calculated zero-dip response with the calculated non-zero-dip response yields the dip effect. A response is also modeled to exclude the non-linearity of the shoulder effect. Comparing the calculated linear response (obtained, e.g. by the Born approximation) with the calculated zero-dip response yields the nonlinear shoulder effect. The nonlinear shoulder effect and/or the dip effect may then be corrected for by subtracting them from the raw or pre-processed measurements.

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 method is disclosed for real-time (well-site) resistivity anisotropy determination using array lateral logs or any other unfocused, lateral-type measurements, and array induction logs or any other focused, induction-type measurements. Near-vertical wells with a deviation angle of less than 30 degrees are considered. Since with a lateral log, at each logging depth the injected current has both horizontal and vertical components, the data contains information related to both horizontal (Rh) and vertical (Rv) resistivities. With array induction tool, the induced current in near-vertical wells has only a horizontal component, and the induction data contain information related to Rh only. Having those two data sets acquired in the same well, it is possible to instantly estimate the formation resistivity anisotropy using square of a ratio between borehole and invasion corrected lateral and induction focused logs.

Abstract: A method for determining the anisotropic resistivity properties of a subterranean formation traversed by a borehole utilizing a multi-component induction logging tool. The method utilizes the measured phase and attenuation signals induced by eddy currents in the formation to determine the azimuthal angle and to create a second set of signals based on the measured signals and the azimuthal angle. The anisotropic resistive properties, as well as the dip angle, are then simultaneously derived from the second set of signals by means of minimizing error functions within an inversion model.

Abstract: A method for determining formation resistivity anisotropy in a wellbore environment. The method of the present invention effectively extends the dynamic range of the existing well logging service of the multi-component induction tool, allowing the use of this service in wells drilled with conductive WBM systems. A sequential inversion processing of galvanic array lateral log HDLL/MLL data or DLL/MLL and also multi-component induction log (3DEXSM) data is used. The formation resistivity structure of the near wellbore environment is determined using the galvanic measurements of the array lateral log tool.

Abstract: A rock classification system involves the use of a Ternary Diagram (TD) Model and a set of rules in a rule base. A computer, which stores a rock classification software which includes the rule base, will be responsive to certain data points from a Spectroscopy Sonde, will compare each data point with each of the rules in the rule base, and, when a match is found, will generate a specific rock classification for that data point. When a plurality of data points are input to the computer, a corresponding plurality of rock classifications are generated.