Systems and methods for estimating standoff and/or caliper in a wellbore for oil-based mud drilling are provided. The systems include a sensor having a primary electrode and at least two secondary electrodes, and an electronics subsystem having a controller and a processor for driving the system and correlating current measurements with standoff and/or caliper. The electrodes are positioned relative to one another such that there is a distinct flow of current between the primary electrode and each secondary electrode. In operation, a single excitation frequency is applied to the primary electrode and a simultaneous measurement of current flowing between the primary electrode and each secondary electrode is obtained. Standoff is estimated from the measurements. The estimations can be independent of formation properties when an appropriate excitation frequency is used.

Systems and methods for estimating standoff and/or caliper in a wellbore for oil-based mud drilling are provided. The systems include a sensor having a primary electrode and at least two secondary electrodes, and an electronics subsystem having a controller and a processor for driving the system and correlating current measurements with standoff and/or caliper. The electrodes are positioned relative to one another such that there is a distinct flow of current between the primary electrode and each secondary electrode. In operation, a single excitation frequency is applied to the primary electrode and a simultaneous measurement of current flowing between the primary electrode and each secondary electrode is obtained. Standoff is estimated from the measurements. The estimations can be independent of formation properties when an appropriate excitation frequency is used.

A gauging machine for inspecting bore diameters of a workpiece includes a reference fixture, a first wide range bore gauge arranged on a first three-dimensional positioning apparatus to facilitate inspection of a first set of bores aligned along parallel axes, and a second wide range bore gauge arranged on a second three-dimensional positioning apparatus to facilitate inspection of one bore or a plurality of bores aligned along parallel axes. The gauging machine facilitates inspection of bores on a plurality of different workpieces having different overall dimensions, a different number of bores, different positioning of bores, and/or different size bores, without requiring retooling of the gauging machine.

A gauging machine for inspecting bore diameters of a workpiece includes a reference fixture, a first wide range bore gauge arranged on a first three-dimensional positioning apparatus to facilitate inspection of a first set of bores aligned along parallel axes, and a second wide range bore gauge arranged on a second three-dimensional positioning apparatus to facilitate inspection of one bore or a plurality of bores aligned along parallel axes. The gauging machine facilitates inspection of bores on a plurality of different workpieces having different overall dimensions, a different number of bores, different positioning of bores, and/or different size bores, without requiring retooling of the gauging machine.

Various downhole logging tools and methods of using and making the same are disclosed. In one aspect, a downhole logging tool for inspecting one or more well tubulars includes a housing adapted to be supported in the one or more well tubulars by a support cable. A first transmitter, a second transmitter and a third transmitter are positioned in longitudinally spaced-apart relation in the housing and are operable to generate magnetic fields. Driving circuitry is operatively coupled to the first transmitter, the second transmitter and the third transmitter to selectively fire the first transmitter, the second transmitter and the third transmitter in multiple transmission modes to generate magnetic fields to stimulate pulsed eddy currents in the one or more well tubulars. A first receiver is positioned in the housing to sense decaying magnetic fields created by the pulsed eddy currents. Electronic circuitry is operatively coupled to the first receiver to determine a parameter of interest of the one or more well tubular from the sensed decaying magnetic fields.

Various downhole logging tools and methods of using and making the same are disclosed. In one aspect, a downhole logging tool for inspecting one or more well tubulars includes a housing adapted to be supported in the one or more well tubulars by a support cable. A first transmitter, a second transmitter and a third transmitter are positioned in longitudinally spaced-apart relation in the housing and are operable to generate magnetic fields. Driving circuitry is operatively coupled to the first transmitter, the second transmitter and the third transmitter to selectively fire the first transmitter, the second transmitter and the third transmitter in multiple transmission modes to generate magnetic fields to stimulate pulsed eddy currents in the one or more well tubulars. A first receiver is positioned in the housing to sense decaying magnetic fields created by the pulsed eddy currents. Electronic circuitry is operatively coupled to the first receiver to determine a parameter of interest of the one or more well tubular from the sensed decaying magnetic fields.

Systems and methods for detection of downhole tubulars. A method may include disposing a corrosion detection tool in a plurality of concentric pipes, wherein the corrosion detection tool comprises a transmitter and a plurality of receivers; measuring a signal to provide a measured response; calibrating a log, wherein the calibrating comprises matching a nominal value of the measured response to a synthetic response to provide calibrated measurements; running a first inversion, wherein the first inversion comprises a first subset of the calibrated measurements that are used to compute a first estimate of properties of each of the concentric pipes; identifying pipes with an estimated thickness change from a nominal thickness to provide identified concentric pipes; selecting an innermost concentric pipe from the identified concentric pipes for computing an impulse response for deconvolution for improving vertical resolution of the measured response; applying deconvolution to a second subset of the calibrated measurements to provide calibrated and deconvolved measurements; and running a second inversion on the second subset of calibrated and deconvolved measurements, wherein the second inversion comprises at least one property of the plurality of concentric pipes.

An aperture measuring device and aperture measuring method for measuring the size of the aperture of a through-hole in a conductive structure is described to reduce the aperture measurement time and improve the working efficiency. The aperture measuring device includes: an aperture testing component for being inserted into the through-hole, wherein the aperture measuring device includes a plurality of resistor segments with different diameters, the individual resistor segments being successively connected in series in an order of the sizes of their diameters; and a measuring module for measuring the resistance value of a resistor segment unable to be inserted into the through-hole in the aperture testing component to determine the size of the aperture of the through-hole.

An aperture measuring device and aperture measuring method for measuring the size of the aperture of a through-hole in a conductive structure is described to reduce the aperture measurement time and improve the working efficiency. The aperture measuring device includes: an aperture testing component for being inserted into the through-hole, wherein the aperture measuring device includes a plurality of resistor segments with different diameters, the individual resistor segments being successively connected in series in an order of the sizes of their diameters; and a measuring module for measuring the resistance value of a resistor segment unable to be inserted into the through-hole in the aperture testing component to determine the size of the aperture of the through-hole.

Embodiments of the present disclosure are directed toward a system and method to calibrate calipers of a downhole tool. Specifically, a calibration tool includes a substantially cylindrical calibration ring. The calibration tool also includes a finger coupled to the calibration ring. The finger is configured to engage with the downhole tool such that the calibration ring is mounted to the downhole tool and is coaxial with a tool axis of the downhole tool.