Abstract: Methods may include emplacing a resistivity logging tool in a borehole; stimulating an interval of the formation in the borehole; obtaining at least one resistivity log of the interval of the formation, wherein the resistivity log comprises a survey of one or more depths into the formation; determining a radial invasion of the stimulating fluid into the interval of the formation; and inverting the radial invasion to obtain an input and entering the input into an effective medium model; solving the effective medium model and generating an effective wormhole radius profile and thickness for the interval of the formation.

Abstract: A method and system for evaluation of a hydrocarbon-bearing shale formation employs a data processing system that defines a response model that relates first data representing measured petrophysical properties of the shale formation at a given location to second data representing volume fractions for a particular set of formation components at the given location. The first data includes hydrogen index at the given location, and the particular set of formation components of the second data include a number of mineral components and a number of hydrocarbon-bearing components. The hydrocarbon-bearing components include at least one kerogen component. A computation solver processes the response model along with the first data to solve for the second data. The solved second data representing the volume fraction of the at least one kerogen component is processed to derive at least one ratio that is indicative of kerogen maturity at the given location.

Abstract: A method can include receiving measurements of a fluid mixture where the measurements are acquired by at least one downhole tool; performing a multiphysics inversion of the measurements to generate nuclear parameter values for the fluid mixture; performing a multivariate interpolation using the generated nuclear parameter values that accounts for intermolecular interactions in the fluid mixture; and determining a composition of the fluid mixture based on the multivariate interpolation.

Abstract: A method to estimate water saturation in electromagnetic measurements includes making an electromagnetic measurement and performing at least one of (a) creating an analytical forward model of the EM measurement, (b) creating a numerical finite difference forward model of the EM measurement, and (c) performing an inversion. The method also includes removing at least one petrophysically-adverse alteration of EM measurements in the frequency range from 1 Hz to 100 MHz. A petrophysically-adverse alteration is due to the presence of at least one of the following: pyrite, graphitic-precursors, magnetite, and other conductive minerals.

Abstract: A formation characterization system can include a processor; memory accessibly by the processor; instructions stored in the memory and executable by the processor to instruct the system to: acquire induction measurements in a borehole in a formation using an induction tool; determine dielectric properties of the formation using the induction measurements; and generate a log that characterizes particles in the formation based on the dielectric properties.

Abstract: A method for evaluating inflow or outflow in a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The pressure measurements may then be processed to obtain an interval density of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of interval densities corresponding to various wellbore intervals. The interval density may be measured during static conditions or while drilling and may be further processed to compute a density of an inflow constituent in the annulus. Changes in the computed interval density with time may be used as an indicator of either an inflow event or an outflow event.

Abstract: An electromagnetic measurement tool for making multi-frequency, full tensor, complex, electromagnetic measurements includes a triaxial transmitter and a triaxial receiver deployed on a tubular member. An electronic module is configured to obtain electromagnetic measurements at four or more distinct frequencies. The measurement tool may be used for various applications including obtaining a resistivity of sand layers in an alternating shale-sand formation; computing a dielectric permittivity, a conductivity anisotropy, and/or a permittivity anisotropy of a formation sample; and/or identifying formation mineralization including discriminating between pyrite and graphite inclusions and/or computing weight percent graphite and/or pyrite in the formation sample.

Abstract: An electromagnetic measurement tool for making multi-frequency, full tensor, complex, electromagnetic measurements includes a triaxial transmitter and a triaxial receiver deployed on a tubular member. An electronic module is configured to obtain electromagnetic measurements at four or more distinct frequencies. The measurement tool may be used for various applications including obtaining a resistivity of sand layers in an alternating shale-sand formation; computing a dielectric permittivity, a conductivity anisotropy, and/or a permittivity anisotropy of a formation sample; and/or identifying formation mineralization including discriminating between pyrite and graphite inclusions and/or computing weight percent graphite and/or pyrite in the formation sample.

Abstract: A method of performing a wellbore operation includes: circulating a doped wellbore fluid comprising a non-radioactive doped particulate material in a wellbore; and logging the wellbore with a logging-while-drilling tool to determine at least one characteristic of the doped wellbore fluid. A method of performing a wellbore operation includes: circulating a doped wellbore fluid comprising a non-radioactive doped particulate material in a wellbore; logging the wellbore with a logging tool; and determining a location of at least one fracture by elemental spectroscopy measurements.

Abstract: A method for calibrating an electromagnetic core analysis tool is disclosed. The method includes disposing a tilted test loop inside of or outside of a tool having more than one antenna. A uniform test pack, a layered test pack, and an effective media test pack are each disposed in the tool. A signal is induced in a receiver antenna in the tool when a second antenna is energized with a known current of a known frequency. The induced signal is measured and a calibration gain and offset is determined. A corrected signal is produced and compared with the determined signal based on a forward model.

Abstract: Methods and apparatus for characterizing a subterranean formation traversed by a wellbore including collecting data from the formation using a tool wherein the tool collects data to form an azimuthal image, characterizing a section of the formation comprising data and images acquired in a high angle wellbore section or horizontal wellbore section using a parametric model, and performing an inversion using apparent densities and volumetric photoelectric factor images to build a formation model wherein the inversion is tailored for high angle wellbore sections and/or horizontal wellbore sections.

Abstract: A method to estimate water saturation in electromagnetic measurements includes making an electromagnetic measurement and performing at least one of (a) creating an analytical forward model of the EM measurement, (b) creating a numerical finite difference forward model of the EM measurement, and (c) performing an inversion. The method also includes removing at least one petrophysically-adverse alteration of EM measurements in the frequency range from 1 Hz to 100 MHz. A petrophysically-adverse alteration is due to the presence of at least one of the following: pyrite, graphitic-precursors, magnetite, and other conductive minerals.

Abstract: A method of performing a wellbore operation includes: circulating a doped wellbore fluid comprising a non-radioactive doped particulate material in a wellbore; and logging the wellbore with a logging-while-drilling tool to determine at least one characteristic of the doped wellbore fluid. A method of performing a wellbore operation includes: circulating a doped wellbore fluid comprising a non-radioactive doped particulate material in a wellbore; logging the wellbore with a logging tool; and determining a location of at least one fracture by elemental spectroscopy measurements.

Abstract: Methods and apparatus for characterizing a subterranean formation traversed by a wellbore including collecting data from the formation using a tool wherein the tool collects data to form an azimuthal image, characterizing a section of the formation comprising data and images acquired in a high angle wellbore section or horizontal wellbore section using a parametric model, and performing an inversion using apparent densities and volumetric photoelectric factor images to build a formation model wherein the inversion is tailored for high angle wellbore sections and/or horizontal wellbore sections.

Abstract: A system for drilling a subterranean wellbore includes a bottom hole assembly (BHA) coupled to a downhole end of a drill string. The BHA includes an electronic controller having a processor. The drill string includes downhole and uphole portions with the downhole portion made up of wired drill pipe and the uphole portion made up of non-wired drill pipe. The downhole portion further includes at least one downhole tool or sensor sub in communication with the BHA via the wired drill pipe communication link. Methods for making sensor measurements, downlinking data and/or commands to the BHA, and actuating a downhole tool make use of the system.

Abstract: A method for estimating equivalent top of fluid level or a theoretical surface annular back pressure in a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The pressure measurements may then be processed to compute the equivalent top of fluid level and/or theoretical surface annular back pressure of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of values corresponding to various wellbore intervals. The equivalent top of fluid level and/or theoretical surface annular back pressures may be used in automated managed pressure drilling operations.

Abstract: A method includes accepting as input to a processor measurements of a characteristic of a subsurface formation made at a plurality of spaced apart positions along a pipe string moved along a wellbore. Measurements are made of pipe string depth in the wellbore from the Earth's surface. The measurements of pipe string depth include measurements of apparent depth of each of the spaced apart locations. The subsurface formation is identified from the measurements of the characteristic. A true depth of the subsurface formation is made using the measurements of pipe string depth and apparent depth of the formation from each of the spaced apart positions. A record of measurements of the characteristic with respect to depth corrected for changes in length of the pipe string caused by axial forces along the pipe string is generated.

Abstract: A method for evaluating inflow or outflow in a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The pressure measurements may then be processed to obtain an interval density of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of interval densities corresponding to various wellbore intervals. The interval density may be measured during static conditions or while drilling and may be further processed to compute a density of an inflow constituent in the annulus. Changes in the computed interval density with time may be used as an indicator of either an inflow event or an outflow event.

Abstract: A method for automatic interpretation of bulls-eye and sinusoidal features observed in LWD images is disclosed. In some embodiments, the method includes an automatic workflow for extracting smooth contours from images that demarcate boundaries of structural features, followed by projection of the contours to three-dimensional (3D) point clouds in the well coordinate system for structural interpretation. The method may characterize both sinusoidal features and bulls-eye features, taking into account variations of formation dip/azimuth, or well inclination/azimuth, on the topology of a structural feature. The disclosed method may be sufficiently fast for use in real-time analysis and interpretation, or to provide constraints for physics-based data inversion processing.

Abstract: A tool is for use in a borehole during drilling with a drilling fluid circulating in the borehole. The tool may include a housing, a plurality of spaced apart radio frequency (RF) transmitters carried by the housing, spaced apart RF receivers carried by the housing, and a controller to communicate with the plurality of transmitters and the receivers. The controller may, at a given depth within the borehole, determine attenuation resistivity measurements and phase-shift resistivity measurements both corresponding to different radial distances from the borehole. The controller may also determine when a fracture has occurred in the geological formation at the given depth allowing the drilling fluid to intrude into the geological formation based upon the attenuation resistivity measurements and the phase-shift resistivity measurements.