An acoustic transducer array and method of making same. A first metal layer is deposited on a first side of a piezoelectric composite to form a common electrode and a second metal layer is provided over the obverse side. Portions of the second metal layer are removed to create a plurality of individual electrodes. A third metal layer may be deposited onto the plurality of individual electrodes, the third metal layer being thicker than the second metal layer. The individual electrodes extend beyond the piezoelectric composite in the elevation direction to create electrode leads. Metal layers may be provided by lithography, a wireframe or a foil sheet.

Systems and methods for obtaining a calibrated permittivity dispersion measurements of a subsurface formation by measuring an impedance of the subsurface formation using a borehole imager at a first one or more frequencies; measuring a permittivity of the subsurface formation using a reference tool at a second one or more frequencies; calculating a first dispersion curve of the permittivity of the subsurface formation based at least in part on the measured impedance of the subsurface formation at the first one or more frequencies; extrapolating the permittivity of the subsurface formation to the second one or more frequencies using the calculated first dispersion curve of the permittivity of the subsurface formation; calibrating the permittivity of the subsurface formation based at least in part on the extrapolated permittivity of the subsurface formation and the measured permittivity of the subsurface formation; and generating a second dispersion curve of the permittivity of the subsurface formation based at least in part on one or more of the calibrated permittivity of the subsurface formation at the first one or more frequencies and the measured permittivity of the subsurface formation at the second one or more frequencies.

A method and assembly for calibrating downhole imaging tools includes a calibrator mechanism with a known electromagnetic response, whereby the calibrator mechanism is simultaneously engaged with a plurality of injector electrodes and the at least one return electrode carried on a pad of the downhole imaging tool. A current is injected into the calibrator mechanism by the injector electrodes and the response of the tool is measured. The calibrator mechanism if formed of a homogenous material or fluid so that the electromagnetic response is uniform throughout. The measured electromagnetic response can be compared to the known electromagnetic response and a calibration adjustment can be determined. The calibration adjustment can then be applied to future downhole measurements obtained during an imaging operation.

The disclosure presents a process for sharpening an image data representation of collected measurements from a subterranean formation. The sharpening process utilizes an azimuthal filter applied to azimuthal radial ranges around a borehole to designate azimuthal bins. The azimuthal filter utilizes a set of filter coefficients to modify an azimuthal target bin. The set of filter coefficients is a devolution set as it contains at least one positive and one negative filter coefficient. The filter ratio of positive to negative filter coefficients can be adjusted utilizing the statistical uncertainty of the collected measurements and a targeted filter ratio. In some aspects, an axial filter process, also using a binning methodology, can be applied to the collected measurements, where the azimuthal and axial filtered values can be combined for the final image representation. The azimuthal and axial processes can be executed in serial or parallel process flows.

A well tool can be used in a wellbore that can measure characteristics of an object in the wellbore. The well tool includes an ultrasonic transducer for generating an ultrasonic wave in a medium of the wellbore. The ultrasonic transducer includes a front layer, a rear layer, backing material coupled to the rear layer, and piezoelectric material coupled to the front layer and to the backing material. The rear layer can improve signal-to-noise ratio of the transducer in applications such as imaging and caliper applications.

Gadolinium- or boron-doped drilling mud is used during drilling so that it will penetrate all natural cracks in the formation that intersect with the wellbore. Once cased, cemented and washed, the doped mud will only be in the fractures. Pulsed neutron logging is performed, and natural factures thereby characterized.

According to one embodiment, a wall detection device includes an acquirer and processing circuitry. The acquirer acquires a point cloud, which includes a series of coordinates of a plurality of points corresponding to a first wall and a second wall that oppose each other. The processing circuitry detects a first detected wall and a second detected wall based on a model and the acquired point cloud, the model representing a first plane which corresponds to the first detected wall and indicates a surface of the first wall and a second plane which corresponds to the second detected wall and indicates a surface of the second wall, and the model representing the first plane and the second plane being parallel to each other.

Deconvolution-based processing of ultrasonic waveforms enables robust calculation of two-way travel time for an ultrasonic caliper, particularly in the presence of multiple, proximal reflectors (e.g., mud cake, formation, casing, cement, etc.).

A method and system for estimating a mud angle. A method may include disposing a downhole tool into a borehole, energizing a button array, transmitting a current from the electrode into a formation, recording the current from the formation with a return electrode to obtain a plurality of measurements, identifying at least one low resistivity zone from the plurality of measurements to produce a measurement set, inverting the measurement set to find a mud angle vector, removing the mud angle vector from the measurement set to obtain a corrected measurement, and obtaining an electrical image using the corrected measurement. A system may include a downhole tool, a conveyance, and an information handling system. The downhole tool may further include at least one electrode and at least one return electrode.

Systems and methods for determining perforation orientations of a subterranean formation for a hydraulic fracturing treatment are presented. The method comprises identifying in-situ stresses for a portion of a wellbore formed from a terranean surface into a subterranean formation. The method also includes transforming the in-situ stresses from a global coordinate system to a wellbore coordinate system at a perforation cluster of the wellbore that comprises at least one perforation tunnel for a hydraulic fracturing treatment. The in-situ stresses are transformed from the wellbore coordinate system to a perforation coordinate system through at least one rotation matrix. Pressure coefficients and a breakdown pressure for each trial perforation phase angle at a perforation cluster determined, and a perforation point in the wellbore coordinate system is calculated for each trial perforation phase angle of the perforation cluster. The perforation point in the wellbore coordinate system is transformed to the translated global coordinate system for each trial perforation phase angle. A target perforation phase angle is selected at a minimum breakdown pressure for the perforation cluster, and a perforation azimuth and perforation dip is calculated for the perforation cluster at the minimum breakdown pressure for the target perforation phase angles.