Abstract: An inversion-based method has been developed to evaluate up to 5 or 6 nested casings by utilizing complementary sensitivities from time-domain collocated (relatively shallow) and multi-frequency, multi-spacing non-collocated (both relatively shallow and relatively deeper) pulsed eddy current measurements. Stand-alone inversion-based techniques are also disclosed to process time-domain collocated sensor measurements, which may come from single or multiple sensors of different lengths.

Abstract: Systems and methods to determine a thickness profile of nested metallic pipes can include processing long sections (windows) of induction multi spacing and multi frequency noncollocated sensor measurements (attenuation and phase). The systems and methods also include using an inversion based process to deconvolve the tool transfer function from the surrounding pipe structure and its anomalies by running an axisymmetric finite element method (FEM modeling solver with a model in an inversion loop.

Abstract: A system and apparatus are described for measuring magnetic flux in a wellbore casing. In an example, the apparatus includes a primary magnet and a sensor for measuring magnetic flux in the wellbore casing created by the primary magnet. The primary magnet can have magnetic pole pieces at either end that help guide the magnetic flux into the wellbore casing. Focusing magnets can be placed on both ends of the primary magnet so that the focusing magnets are separated from the primary magnet by the magnetic pole pieces. The magnetic flux created by the focusing magnets reduces dispersion of the primary magnet's magnetic flux by forcing magnetic flux from the primary magnet that would otherwise disperse to flow toward the sensor. The sensor can output a signal with magnetic flux readings. A computing device can receive the signal and detect discontinuities in the wellbore casing.

Abstract: A system and apparatus are described for measuring magnetic flux in a wellbore casing. In an example, the apparatus includes a primary magnet and a sensor for measuring magnetic flux in the wellbore casing created by the primary magnet. The primary magnet can have magnetic pole pieces at either end that help guide the magnetic flux into the wellbore casing. Focusing magnets can be placed on both ends of the primary magnet so that the focusing magnets are separated from the primary magnet by the magnetic pole pieces. The magnetic flux created by the focusing magnets reduces dispersion of the primary magnet's magnetic flux by forcing magnetic flux from the primary magnet that would otherwise disperse to flow toward the sensor. The sensor can output a signal with magnetic flux readings. A computing device can receive the signal and detect discontinuities in the wellbore casing.

Abstract: An inversion-based method has been developed to evaluate up to 5 or 6 nested casings by utilizing complementary sensitivities from time-domain collocated (relatively shallow) and multi-frequency, multi-spacing non-collocated (both relatively shallow and relatively deeper) pulsed eddy current measurements. Stand-alone inversion-based techniques are also disclosed to process time-domain collocated sensor measurements, which may come from single or multiple sensors of different lengths.

Abstract: Embodiments included herein are directed towards a system and method for analyzing an oilfield casing using an apparent thickness approach. Embodiments may include providing an induction instrument having at least one of a transmitter and a receiver configured to operate at one or more frequencies. Embodiments may further include generating, using data acquired by the induction instrument, one or more apparent thickness transforms for at least one of a measured attenuation and a phase response associated with an oilfield casing, wherein generating includes assuming a proportionate increase in all casing thicknesses.

Abstract: Methods and systems are provided that predict electromagnetic properties of drilling mud and a formation, which involve a logging tool that measures current injected into a measurement zone adjacent a sensor electrode at multiple frequencies. The measured currents at the multiple frequencies are processed to determine complex impedances for the sensor electrode at the multiple frequencies. The complex impedances are used to generate input data, which is supplied to a system of artificial neural networks (ANNs) that is configured to predict and output electromagnetic properties of the drilling mud and the formation within the measurement zone and possibly tool standoff based on the input data. The system of ANNs can employ a cascaded architecture of multiple ANNs. The electromagnetic properties or tool standoff predicted by the system of ANNs can be used to construct a borehole image over varying azimuth and depth.

Abstract: Systems, computer-readable media, and methods for valuating measurement data, of which the method includes obtaining a first model of a subsurface volume, determining a baseline control parameter based on the first model, receiving new measurement data measured using a data collection device, the new measurement data representing one or more characteristics of the subsurface volume, and obtaining a second model of the subsurface volume based in part on the new measurement data. The first model is not based on the new measurement data. Further, the method includes determining an enhanced control parameter based on the second model, determining an enhanced value corresponding to the second model using the enhanced control parameter, determining a realized value corresponding to the second model using the baseline control parameter, and calculating a value of the new measurement data by comparing the enhanced value and the realized value.

Abstract: Embodiments of the present disclosure are directed towards a method for obtaining and analyzing flux leakage data. Embodiments may include measuring, using a magnetic flux leakage tool, magnetic flux leakage data from a casing and determining sensor liftoff data from the flux leakage data. Embodiments may also include performing outward analytic continuation of the magnetic flux leakage data from a sensor plane to one or more additional planes and extrapolating back from the one or more additional planes to a surface. Embodiments may include applying a model-based parametric inversion to the magnetic field flux leakage data and determining, based upon, at least in part, the model-based parametric inversion, a shape and size of a corresponding corroded area associated with the casing.

Abstract: Methods and systems for characterizing subterranean formations are described herein. One method includes performing electromagnetic logging measurements along a portion of a borehole traversing the subterranean formation using an electromagnetic logging tool to obtain electromagnetic data. The method also includes processing the electromagnetic data to determine a plurality of one dimensional formation models associated with the portion of the borehole. A two dimensional pixel grid is determined using the plurality of one dimensional formation models. The method further includes determining a two dimensional formation model for the subterranean formation by performing an inversion of the electromagnetic data using the two dimensional pixel grid. The methods and systems described herein can be used to steer a bottom-hole assembly during well placement.

Abstract: Inversion-based workflows are provided for real-time interpretation of the electromagnetic (EM) look-around and look-ahead measurements. The profile of a look-around zone is determined by interpreting EM measurements of a look-around zone. The profile of the look-around zone characterizes formation dip as well as vertical resistivity or resistivity anisotropy of one or more formation layers of the look-around zone. The profile of a look-ahead zone is determined by interpreting EM measurements of the look-ahead zone. The profile of the look-ahead zone characterizes formation dip as well as horizontal resistivity, vertical resistivity or anisotropy of one or more formation layers of the look-ahead zone. The workflows can also involve interpretation of look-around resistivity measurements to aid in the characterization of the look-around zone.

Abstract: A method and system is provided for drilling a wellbore that traverses a geological formation using a drilling tool. The method and system derives a plurality of formation models that characterize the geological formation. The number of formation models represent layer structures with a heterogeneity (such a fault) offset laterally at variable distance relative to position of the drilling tool. Simulated directional resistivity data of the drilling tool is derived from the plurality of formation models. Certain simulated directional resistivity data are combined or selected for processing as multi-dimensional cross-plot data. Measured directional resistivity data obtained by the drilling tool is used to evaluate the multi-dimensional cross-plot data to determine distance of the heterogeneity relative to position of the drilling tool.

Abstract: Methods and systems are provided that predict electromagnetic properties of drilling mud and a formation, which involve a logging tool that measures current injected into a measurement zone adjacent a sensor electrode at multiple frequencies. The measured currents at the multiple frequencies are processed to determine complex impedances for the sensor electrode at the multiple frequencies. The complex impedances are used to generate input data, which is supplied to a system of artificial neural networks (ANNs) that is configured to predict and output electromagnetic properties of the drilling mud and the formation within the measurement zone and possibly tool standoff based on the input data. The system of ANNs can employ a cascaded architecture of multiple ANNs. The electromagnetic properties or tool standoff predicted by the system of ANNs can be used to construct a borehole image over varying azimuth and depth.

Abstract: Embodiments of the present disclosure are directed towards a method for obtaining and analyzing flux leakage data. Embodiments may include measuring, using a magnetic flux leakage tool, magnetic flux leakage data from a casing and determining sensor liftoff data from the flux leakage data. Embodiments may also include performing outward analytic continuation of the magnetic flux magnetic flux leakage data from a sensor plane to one or more additional planes and extrapolating back from the one or more additional planes to a surface. Embodiments may include applying a model-based parametric inversion to the magnetic field flux leakage data and determining, based upon, at least in part, the model-based parametric inversion, a shape and size of a corresponding corroded area associated with the casing.

Abstract: Embodiments included herein are directed towards a system and method for analyzing an oilfield casing using an apparent thickness approach. Embodiments may include providing an induction instrument having at least one of a transmitter and a receiver configured to operate at one or more frequencies. Embodiments may further include generating, using data acquired by the induction instrument, one or more apparent thickness transforms for at least one of a measured attenuation and a phase response associated with an oilfield casing, wherein generating includes assuming a proportionate increase in all casing thicknesses.

Abstract: A method for characterizing a subterranean formation, the method comprising: performing electromagnetic logging measurements along a portion of a borehole traversing the subterranean formation using an electromagnetic logging tool to obtain electromagnetic data; determining one or more initial approximations for one or more electromagnetic properties associated with a two dimensional imaging plane modeling the subterranean formation; determining one or more initial approximations for a relative orientation between the two dimensional imaging plane and an orientation of a trajectory along the portion of the borehole; and performing a first inversion using (i) the one or more initial approximations of the one or more electromagnetic properties, (ii) the one or more initial approximations for the relative orientation between the two dimensional imaging plane and the orientation of the trajectory, and (iii) the electromagnetic data to estimate an orientation of the two dimensional imaging plane relative to the or

Abstract: Systems and methods are disclosed for well logging using radiation detection and/or emission of gamma rays. A method according to the disclosure includes collecting data from the subterranean formation using a nuclear density tool, wherein the nuclear density tool is configured to collect data to form an azimuthal image. The method further includes characterizing a section of the subterranean formation comprising data and images acquired in a high angle wellbore section, a horizontal wellbore section, or a combination thereof. The method additionally includes performing a parallel inversion using apparent densities and volumetric photoelectric factor images to build a formation model, wherein the parallel inversion comprises a high angle workflow that models high angle wellbore sections and a horizontal workflow that models horizontal wellbore sections.

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: Methods for determining oil-water contact positions and water zone resistivities are provided. In one example, the method may involve performing a 1D inversion on data collected by a resistivity logging tool. Further, the method may involve scanning a resistivity profile of a reservoir generated by the 1D inversion for a boundary position below the resistivity logging tool. Furthermore, the method may involve applying a local residual weighted average on the boundary position to generate an initial estimation of an oil-water contact position and inverting the initial estimation of the oil-water contact to generate water zone resistivity and a modified oil-water contact position. Additionally, the method may involve running a smoothing local post-processing operation to generate a layered model and performing a 2D inversion on the layered model.

Abstract: Systems, methods, and apparatuses to generate a formation model are described. In one aspect, a logging system includes a transmitter to produce an electromagnetic field in a borehole, a receiver in the borehole to detect a first field signal induced by the electromagnetic field at a first depth of investigation and a second field signal induced by the electromagnetic field at a second depth of investigation, and a modeling unit to perform a first one-dimensional inversion on the first field signal and a second one-dimensional inversion on the second field signal, build a two-dimensional model from the first one-dimensional inversion and the second one-dimensional inversion, and perform a two-dimensional inversion on the two-dimensional model to generate a two-dimensional formation model.