Abstract: A method for determining dip of rock formations penetrated by a wellbore using multiaxial induction measurements and imaging measurements made from within the wellbore includes estimating dip from the multiaxial induction measurements. Dip is also estimated from the imaging measurements. The dip is determined by combining the induction and imaging measurements.

Abstract: A data reduction method for transmission of a borehole image to the surface of the earth using restricted band widths of LWD telemetry systems. The data reduction method is based on the measurement physics rather than mathematical compression algorithms. Measured data from a sensor are fitted, within the logging tool, to a response function relating sensor response to a parameter of interest. The coefficients of the fitted response function are scaled and then telemetered to the surface. The measured data are reconstructed at the surface by combining the telemetered coefficients with the response function. A borehole image is formed by combining reconstructed reduced data. Parameters of dipping beds intersecting the borehole can be determined from the coefficients.

Abstract: The present invention provides a method and apparatus for logging an earth formation and acquiring subsurface information wherein a logging tool is conveyed in borehole to obtain parameters of interest. The parameters of interest obtained may be density, acoustic, magnetic or electrical values as known in the art. The parameters of interest may be transmitted to the surface at a plurality of resolutions using a multi-resolution image compression method. Parameters of interest are formed into a plurality of Cost Functions from which Regions of Interest are determined to resolve characteristics of the Features of interest within the Regions. Feature characteristics may be determined to obtain time or depth positions of bed boundaries and borehole Dip Angle relative to subsurface structures, as well borehole and subsurface structure orientation. Characteristics of the Features include time, depth, and geometries of the subsurface such as structural dip, thickness, and lithologies.

Abstract: Computer-based method and system are disclosed for interpreting dips, dip trends, and mineral based lithofacies data to identify certain geological events in a subsurface formation. The disclosed method/system analyzes dip magnitude and azimuth data to determine the dip trends in the formation. The dip trends are then examined for indications of the presence of certain depositional events, such as build-ups, flow directions instances of scour and fill, direction to thalweg, parallel bedding, indications of fault, and the like. If lithofacies data is available the disclosed method/system can also analyze this data to identify the presence of interbedded sequences and condensed sections. Such an integrated solution saves geoscientists and interpreters an enormous amount of time compared to existing interpretation techniques, allowing them to be much more productive. The disclosed system/method may also be used to help train new and less experienced geoscientists and interpreters.

Abstract: A method of drilling a well. The method includes calculating an estimated formation dip angle, wherein said estimated formation dip angle being based on offset well data, seismic data, core data, pressure data. Next, the method includes drilling a well with a logging while drilling means so that real time logging data is generated along with drilling data and calculating an instantaneous formation dip angle. Next, real time logging data is obtained and a target formation window is projected ahead of the well path that includes a top of formation and a bottom formation. The method includes monitoring the real time logging and drilling data and drilling the well through the target formation window. The method further includes changing the estimated instantaneous formation dip based on the obtained data and adjusting the target formation top and bottom window.

Abstract: This invention relates to surveying wellbores. In particular this invention provides methods of correcting magnetic surveys for the effects introduced by magnetic mud. The method of the present invention comprises, in broad terms, measuring gravitational and magnetic fields at least one position in the wellbore; comparing the measured fields with theoretical values, and introducing scale factors to adapt the measured values to equal the theoretical values thus making it possible to cope with the effects of magnetic mud.

Abstract: The present invention provides method for detecting the possible presence of surfaces layers of diagenetic origin by establishing divergence between well signatures such as logs, particularly for use in predominantly carbonate reservoirs.

Abstract: A method for forming a borehole image of an azimuthally sensitive borehole or formation parameter is disclosed. Such a borehole image may be formed, for example, by processing logging sensor data with a predetermined sensor response function (also referred to herein as a probability density function) to acquire probabilistically distributed sensor data. The sensor data may be distributed in either one-dimension (azimuthal) or two-dimensions (azimuthal and axial). Certain embodiments of this invention may be advantageously utilized in LWD imaging applications and provide for superior image resolution and noise rejection as compared to prior art binning techniques. Exemplary embodiments of the invention also advantageously conserve logging sensor data such that integration of the distributed data over the entire circumference of the tool provides a non-azimuthally sensitive logging measurement.

Abstract: A method for determining a list of survey points for a drilling well includes a feedback loop in which one or more measured parameters are compared with computed or derived parameters. The computed parameters are typically obtained from other/additional measurements. For example, in one exemplary embodiment of the invention, a magnetic least distance vector determined via magnetic ranging is compared with a geometric least distance vector computed from conventional borehole surveying measurements. Estimates of the drilling well azimuth and/or inclination may be adjusted to yield a good agreement between the magnetic and geometric least distance vectors. Exemplary embodiments of the present invention advantageously provide for a substantially real-time determination of a definitive well path for a drilling well as well as a substantially real-time relative placement of the drilling well with respect to a target well.

Abstract: A system and method using inverse-vector processing to iterate through a loop of three steps: set a guide direction, invert opposite vectors, and average vectors to update the guide direction, for smoothing seismic amplitude data. The inverse-vector method can overcome instabilities where the traditional structure-tensor approach fails. The inverse-vector smoothing is simple to implement and more computational efficient. The resultant dips and azimuths are spatially consistent and thus more interpretable and suitable for calculation of curvature and other dip based attributes.

Abstract: The present invention is a method of generating a model of a random field which has directionally varying continuity. First, a tentative model for the random field is specified. Second, connected strings of nodes within the model are identified. Third, a spectral simulation on each of the strings of nodes is performed to determine updated values for the random field. Finally, the tentative model is updated with the data values from the spectral simulations.

Abstract: The present invention provides a method and apparatus for logging an earth formation and acquiring subsurface information wherein a logging tool is conveyed in borehole to obtain parameters of interest. The parameters of interest obtained may be density, acoustic, magnetic or electrical values as known in the art. The parameters of interest may be transmitted to the surface at a plurality of resolutions using a multi-resolution image compression method. Parameters of interest are formed into a plurality of Cost Functions from which Regions of Interest are determined to resolve characteristics of the Features of interest within the Regions. Feature characteristics may be determined to obtain time or depth positions of bed boundaries and borehole Dip Angle relative to subsurface structures, as well borehole and subsurface structure orientation. Characteristics of the Features include time, depth, and geometries of the subsurface such as structural dip, thickness, and lithologies.

Abstract: A medium having a plurality of computer readable files relating to geophysical seismic data recorded thereon. The files include a map display having multiple levels of geographic detail and including a plurality of surface seismic data lines. A plurality of compressed seismic data files is also included, each file producing a corresponding geophysical display when its corresponding surface seismic data line is selected. The files also include a plurality of references to a plurality of full seismic data files. Each of the compressed seismic data files has less information content than its corresponding full seismic data file.

Abstract: A technique includes performing first electromagnetic field measurements to obtain a first set of data and performing second electromagnetic field measurements to obtain a second set of data. The first set of data is relatively sensitive to an effect caused by an air layer boundary and is relatively insensitive to the presence of a resistive body. The second set of data is relatively insensitive to the effect and is relatively sensitive to the presence of the resistive body. The technique includes combining the first and second sets of data to generate a third set of data, which is relatively insensitive to the effect and is relatively sensitive to the presence of the resistive body.

Abstract: A method and a device for detecting discontinuities in a medium by detecting maxima, e.g. in an echo signal of an ultrasound excitation of the media, with maxima corresponding to a given discontinuity being grouped together as a function of coherence criteria applied to the maxima.

Abstract: The present invention provides a method and apparatus for logging an earth formation and acquiring subsurface information wherein a logging tool is conveyed in borehole to obtain parameters of interest. The parameters of interest obtained may be density, acoustic, magnetic or electrical values as known in the art. The parameters of interest are acquired with a plurality of sensors. For time based image data, the time separation values between signals acquired from separate sensors for individual subsurface features are determined. The time separation values may be determined using correlation or other methods illustrated herein or as known in the art. Using known sensor spatial separations and time separation values a drill rate is determined and an incremental depth for the subsurface feature is defined.

Abstract: A relative dip angle of a deviated borehole is determined from natural gamma ray measurements. Dip corrected measurements are processed to determine the thickness of thin beds, and the peak gamma ray response in thin beds.

Abstract: A method for simulating the statistical behavior of atmospheric, meteorological, or other geophysical time series having the following steps: (a) assembling an ensemble of observed data; (b) removing any evident cycles; (c) calculating the eigensystem and expansion coefficient according to the Loève theorem; (d) determining the distribution of said coefficients; (e) generating a larger set of coefficients based on the statistical distribution determined in step (d); and (f) using this larger distribution to create an ensemble of simulated atmospheric, meteorological, or other geophysical time series. The procedure can be used to develop a wide variety of climate statistics, including probabilities of severe events such as cold snaps or heat waves covering specific geographic regions and lasting for various periods of time. It can also be used to provide an evolving conditional estimate of the probabilities of extensive climate deviations persisting until the end of a month, season, or other period.

Abstract: The present invention relates to a user-guided dip picking method from electrical borehole images using Hough Transform. It includes defining a top and bottom reference curve, applying the Hough Transform to the borehole image limited by the top and bottom reference dips so that the Hough Transform space is restrained in the neighborhood of the reference dips. A 1D average trace representing the extrema of the 3D Hough parameter space for each depth is then computed and the extrema exceeding a given threshold are search in this 1D trace. The position in the 3D Hough space of an extremum represents a dip event.

Abstract: The present invention provides a method and apparatus for logging an earth formation and acquiring subsurface information wherein a logging tool is conveyed in borehole to obtain parameters of interest. The parameters of interest obtained may be density, acoustic, magnetic or electrical values as known in the art. The parameters of interest may be transmitted to the surface at a plurality of resolutions using a multi-resolution image compression method. Parameters of interest are formed into a plurality of Cost Functions from which Regions of Interest are determined to resolve characteristics of the Features of interest within the Regions. Feature characteristics may be determined to obtain time or depth positions of bed boundaries and borehole Dip Angle relative to subsurface structures, as well borehole and subsurface structure orientation. Characteristics of the Features include time, depth, and geometries of the subsurface such as structural dip, thickness, and lithologies.

Abstract: A method of determining fluid flow in a volume containing two or more fluid components, including determining a pressure field for the volume. One or more streamlines are determined from the pressure field, and the fluid composition is solved for the fluid composition along the, or each, streamline. The pressure may also be solved along the, or each, streamline. The step of solving along the, or each, streamline may be performed using a finite difference technique.

Abstract: Methods for evaluating the properties of formations surrounding a borehole, include the steps of measuring electrical properties of the formation from within the borehole; deriving a model of parameters of the formation surrounding the borehole; and estimating the properties of the formation using the model to interpret the measured electrical properties. In one aspect of the invention in which the formation includes a series of distributed beds, each bed having specific properties. Another aspect includes grouping similar beds, assigning one or more properties to all of the beds in a group, and using the assigned properties to estimate the properties of the formation for measurements relating to the beds of that group. Another aspect includes making several different measurements of formation electrical properties and simultaneously estimating the formation properties from the different measurements to provide a joint inversion.

Abstract: A Method for Interpreting Seismic Data Using Duplex Waves is described. Whereas substantially horizontal boundaries are readily identified using conventional processing methods based on primary reflections, it has been difficult or impossible to use such methods for locating substantially vertical events or boundaries. The method of the present invention uses secondary reflections to locate substantially vertical events by gathering common source or receiver traces for processing. Wave fields of these gathers are continued downward to the level of the base boundary, then at each discrete depth level, a seismic image of sub-vertical events is formed. The downward-continued gathers correspond to the travel time of the wave from when it left the source or the receiver point, was reflected from the base boundary, and arrived to the corresponding point of the discrete level of wave-field continuation.

Abstract: A reduced order model called the Fundamental Mistuning Model (FMM) accurately predicts vibratory response of a bladed disk system. The FMM software may describe the normal modes and natural frequencies of a mistuned bladed disk using only its tuned system frequencies and the frequency mistuning of each blade/disk sector (i.e., the sector frequencies). The FMM system identification methods—basic and advanced FMM ID methods—use the normal (i.e., mistuned) modes and natural frequencies of the mistuned bladed disk to determine sector frequencies as well as tuned system frequencies. FMM may predict how much the bladed disk will vibrate under the operating (rotating) conditions. Field calibration and testing of the blades may be performed using traveling wave analysis and FMM ID methods. The FMM model can be generated completely from experimental data. Because of FMM's simplicity, no special interfaces are required for FMM to be compatible with a finite element model.

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 for estimating an azimuthal dependence of a parameter of a borehole using logging sensor measurements acquired as a function of azimuth of the logging sensors is provided. The method includes acquiring at least one logging sensor measurement and a corresponding azimuth from a downhole tool. The method further includes processing a convolution of the logging sensor measurement and corresponding azimuth with a predetermined window function to determine convolved logging sensor data for at least one azimuthal position. Certain embodiments of this invention may be advantageously utilized in LWD imaging applications to provide for superior image resolution and noise rejection as compared to prior art imaging techniques.

Abstract: A method for surveying a borehole is disclosed which uses first and second gravity measurement devices disposed at corresponding first and second positions in the borehole and a supplemental reference measurement device disposed at the first position. Exemplary supplemental reference measurement devices include magnetometers and gyroscopes. The method includes determining a reference borehole azimuth at the first position using the supplemental reference measurement device, determining a change in borehole azimuth between the first and second positions using the first and second gravity measurement devices and determining the borehole azimuth at the second position by applying the change in borehole azimuth the reference azimuth. A system adapted to execute the disclosed method and a computer system including computer-readable logic configured to instruct a processor to execute the disclosed method are also provided.

Abstract: The present invention provides a method of determining a property of an earth formation using an acoustic logging tool on a bottomhole assembly (BHA) in a borehole in the earth formation. At least one transmitter is used in the acoustic logging tool for generating acoustic signals into the formation at a first depth of the BHA. A plurality of receivers is used on the logging tool for receiving signals indicative of a parameter of interest. The plurality of receivers are spaced apart axially from the at least one transmitter. The measurements are repeated at least one additional depth of the BHA. The signals at the first depth and subsequent additional depths are sorted into at least one of (i) a common receiver gather, (ii) a common offset gather, and, (iii) a common-midpoint gather, giving re-sorted signals. The re-sorted signals are processed to obtain the parameter of interest.

Abstract: A method for determining rotational offset between first and second gravity measurement devices deployed on a downhole tool is disclosed. The method includes positioning the tool in a previously surveyed section of a borehole that provides a historical survey including at least three previously surveyed azimuthal reference points and utilizing the gravity measurement devices to determine local azimuths at three or more sites in the previously surveyed section of the borehole. The method further includes comparing local azimuths with the historical survey and determining a rotational offset between the measurement devices that gives a best fit between local azimuths and the historical survey. 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 for determining a formation dip angle including extracting features from an acquired well log to obtain a set of features, validating the set of features to obtain a subset of features, generating a layered model using the subset of features, and generating a synthetic log using the layered model and a forward model.

Abstract: A reduced order model called the Fundamental Mistuning Model (FMM) accurately predicts vibratory response of a bladed disk system. The FMM software may describe the normal modes and natural frequencies of a mistuned bladed disk using only its tuned system frequencies and the frequency mistuning of each blade/disk sector (i.e., the sector frequencies). The FMM system identification methods—basic and advanced FMM ID methods—use the normal (i.e., mistuned) modes and natural frequencies of the mistuned bladed disk to determine sector frequencies as well as tuned system frequencies. FMM may predict how much the bladed disk will vibrate under the operating (rotating) conditions. Field calibration and testing of the blades may be performed using traveling wave analysis and FMM ID methods. The FMM model can be generated completely from experimental data. Because of FMM's simplicity, no special interfaces are required for FMM to be compatible with a finite element model.

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 a formation dip angle including extracting features from an acquired well log to obtain a set of features, validating the set of features to obtain a subset of features, generating a layered model using the subset of features, and generating a synthetic log using the layered model and a forward model.

Abstract: A method is provided for processing a seismic 3-D measurement data set, consisting of a multitude of seismic traces, each having a sequence of amplitude values or data points provided with acoustic impedances. The method consists of the following: selecting a reference section at a predetermined location and depth which comprises neighboring trace sections of several seismic traces; determining the similarity between the selected reference section and localized sections of seismic data from the measurement data set; creating a volume of data which corresponds to the measurement data record, using the similarity value which has been determined and allocated to each data point as the attribute. During processing of the seismic data, the sub-surface images are able to be classified by an absolute comparison of the measurement data with a reference sample section as the means of interpretation.

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: Measurements made by a multicomponent logging tool in a borehole are inverted to obtain horizontal and vertical resistivities and formation dip and azimuth angles of a formation traversed by the borehole. The inversion is performed using a generalized Marquardt-Levenberg method. In this generalized Marquardt-Levenberg method, a data objective function is defined that is related to a difference between the model output and the measured data. The iterative procedure involves reducing a global objective function that is the sum of the data objective function and a model objective function related to changes in the model in successive iterations. In an alternate embodiment of the invention, the formation azimuth angle is excluded from the iterative process by using derived relations between the multicomponent measurements.

Abstract: Described is a method for calibrating a spectrophometric apparatus and determining the concentration of an analyte in a sample. This method involves incorporating at least one primary calibration algorithm that uses an order of derivative of absorbance obtained for at least one of a standard set of wavelengths, on a second apparatus. The absorbance values of the sample are measured on the second apparatus at three or more wavelengths from a wavelength calibration table. Interpolated absorbance values are derived from the measured absorbance values for wavelengths from a standard set of wavelengths. A derivative of the interpolated absorbance values is obtained, using the same order of derivative used by the first apparatus. Followed by calculating a concentration of the Analyte in the sample, by applying the Primary Calibration Algorithm to the derivative.

Abstract: It is an object of the present invention to provide a data acquiring method in an infrared imaging apparatus comprising an FTIR device of a continuous scan type for detecting a signal by a multi-element detector. A method of acquiring data from a multi-element detector in an infrared imaging apparatus comprising the steps of scanning each element of the multi-element detector in order synchronously with a sampling signal (12) generated by a reference signal (10) of an interferometer and repeating a series of scanning operations after completely scanning all the elements, thereby carrying out scan, shifting a starting point of sampling in next scan by one element from the starting point of the previous scan, thereby carrying out the same scanning, and repeating the scan at the number of times corresponding to the number of all the elements and then extracting data for each element from storing sampling data, thereby acquiring a data sequence of all the sampling points for each element.

Abstract: Systems and methods are provided for determining various subsurface formation parameters from electromagnetic measurements. Formulas are disclosed for field components in a coordinate system tied to the logging tool. Closed form expressions for a magnetic field distribution in a homogeneous anisotropic medium are derived from Moran-Gianzero formulas. A complete coupling of a tri-axial system of transmitters and receivers is derived in the tool coordinate system, allowing direct inversion of the measurements for horizontal and vertical conductivity and dip and strike (dip-azimuth) angles. Closed form expressions for these four quantities in the low frequency limit are also derived.

Abstract: A new method for determining the anisotropic resistivity properties of a subterranean earth formation traversed by a borehole utilizing a multi-component induction logging tool. The method utilizes the phase and attenuation signals induced by eddy currents in the formation to determine the resistive properties, with or without prior knowledge of the borehole dip angle.

Abstract: An intersection between a first circular arc traced around a given measuring point on a toroidal surface on one side by the extreme end of a segment with a length equal to the curvature radius of traction surfaces of discs and a second circular arc traced around a given measuring point on a toroidal surface on the other side by the extreme end of the segment is obtained in a cross section along the central axis of the power roller. A plurality of intersections are obtained by repeating the process for obtaining the intersection for each of different measuring points on the toroidal surfaces. That specific one of the intersections which is situated nearest to the reference surface of the power roller is selected and it is concluded that the selected intersection is the tilting center of the discs.

Abstract: A generalized mechanism manages ad-hoc type conversions in computer software. A management framework improves type conversion tasks by enabling the modularization of this task by partitioning the work of defining an individual type convertor from the task of identifying and locating type convertors on demand. The details of how type convertors are applied on demand are also a function of the management framework.

Abstract: A method is disclosed for compressing a frame of data representing parameter values, a time at which each parameter value was recorded, and an orientation of a sensor at the time each parameter value was recorded. Generally the method includes performing a two-dimensional transform on the data in the orientation domain and in a domain related to the recording time. In one embodiment, the method includes calculating a logarithm of each parameter value. In one embodiment, the 2-D transform includes generating a Fourier transform of the logarithm of the parameter values in the azimuthal domain, generating a discrete cosine transform of the transform coefficients in the time domain. This embodiment includes quantizing the coefficients of the Fourier transform and the discrete cosine transform. One embodiment of the method is adapted to transmit resistivity measurements made by an LWD instrument in pressure modulation telemetry so that while-drilling images of a wellbore can be generated.

Abstract: A method is disclosed for the determination of horizontal resistivity, vertical resistivity, dip and strike angles of anisotropic earth formations surrounding a wellbore. Electromagnetic couplings among a plural of triad transmitters and triad receivers are measured. Each triad transmitter/receiver consists of coil windings in three mutually orthogonal axes. These measured signals are used to generate initial estimates of the dip angle and strike angle of the formation as well as the anisotropy coefficient and the horizontal resistivity of the formation. An iterative algorithm is then applied using these quantities to finally arrive at more accurate estimates that approach the true values in the formation.

Abstract: The present invention is directed to a method and apparatus for determining the dip angle and horizontal and vertical conductivities of a wellbore during drilling operations. If the dip angle is not known, the present invention allows for the use of multifrequency measurements and a model which maps dielectric permitivities to conductivities to calculate the horizontal conductivity, the vertical conductivity, the horizontal dielectric permitivity, the dielectric permitivity, and the dip angle. If the dip angle is known, the present invention allows a multifrequency tool to be utilized alone to calculate the horizontal conductivity, the vertical conductivity, the horizontal dielectric permitivity, and the vertical dielectric permitivity.

Abstract: The invention comprises a method and system of recognition and translation, stored on a digital storage device with an operating system and running computer applications, such as a personal computer, which recognizes input by the human computer user and transmits output to the human user, which performs non-optical and optical character recognition of characters displayed on the output device of the digital storage device, which automatically recognizes and translates phrases contiguous to and including the phrase upon which the System is activated and which translates words from one written phrase set to a second written phrase set.

Abstract: Method for automatic detection of planar heterogeneities crossing the stratification of an environment.

Abstract: A Tracking Dip Estimator software including a novel Multi-Sine Tracking Software is adapted to be stored in a computer system memory for instructing a processor to produce a “first output” including a plurality of tracks in response to input borehole image data, and a “second output” including a plurality of “dip data” d in response to the plurality of tracks, the Tracking Dip Estimator software generating the “first output” and “second output” by: (1) pre-processing the input borehole image data with a Detector to output a plurality of image edge elements called “reports”, (2) using the reports as input to a Multi-Sine Tracking software that recursively develops a “first output” including a plurality of tracks, or a plurality of connected sets of track points, lying along sinusoidal dip events in the input borehole image data; the Multi-Sine Tracking software has embedded mathematical models for sinusoidal dip events, (3)

Abstract: A processor uses signals from at least two GPS receivers and a 3-component accelerometer located on a stable non-magnetic platform to determine the roll, yaw and pitch angles of the platform, thus providing a measurement of geographic north. The processor also uses signals from a 3-component magnetometer on the platform to determine the magnetic north and thence the magnetic declination. A proton magnetometer is used to provide a check on the measurements of the 3-component magnetometer. Additionally, three single component magnetometers provide a measure of the local magnetic field gradient and serve to monitor artificially induced magnetic fields. An alternate embodiment of the invention uses at least three GPS receivers and may dispense with the 3-component of accelerometer to determine geographic north. Temporal local variations of the earth's magnetic field are tracked and used to correct conventional magnetic well surveys.

Abstract: A method for ascertaining a characteristic of a geological formation surrounding a wellbore. The method comprises first generating a set of data including azimuthal and radial information. A set of parameters indicative of fluid behavior in the formation is determined for each one of at least two azimuths from the generated data. A tool-specific invasion factor is then determined. The characteristic is then determined from the parameters, the azimuthal information, and the invasion factor.