Various embodiments include apparatus and methods to extract reflections from acoustic array data collected from a receiver array. A beam-former can be generated to detect a reflection wave in the presence of a direct wave identified from collected waveforms, where the beam-former can be correlated to receiver and depth for the array. The direct wave and the reflection wave can be separated to extract the reflection wave, where the separation is correlated to receiver and depth for the array. The extracted reflected wave can be used to image and/or analyze entities associated with the borehole. Additional apparatus, systems, and methods are disclosed.

A method of performing acoustic logging comprises generating a first acoustic signal from a first source at a first time, wherein the first source is a first distance away from a wellbore wall, and generating a second acoustic signal from a second source at a second time, wherein the second source is a second distance away from the wellbore wall. The difference between the first time and the second time depends on a calibration value.

An acoustic signal is transmitted from a downhole tool positioned within a wellbore.

Amplitudes and travel times of the acoustic signal received at different azimuthal locations of the downhole tool are measured. Correction factors, each corresponding to a different one of the measured amplitudes, are determined based on the travel times measured at each of the different azimuthal locations. Corrected amplitudes are each determined based on the corresponding measured amplitude and the corresponding correction factor.

This invention relates to a method of correcting eccentricity of ultrasonic image profiles, measured along a section of rock, including the steps of measuring emitted amplitude values (A.sub.0) and measuring transit time values (t.sub.) of ultrasonic acoustic pulses emitted at a range of default angles (), where the amplitude measured at each angle (A.sub.) is determined by an amplitude decay model in relation to the transit time (t.sub.) defined by A .sub.=A.sub..Math.e.sup.t.sup..sup./.Math.I.sub., where is the decay correction factor; and I.sub. is the reflection coefficient of the rock wall.

A method of obtaining position of a downhole tool with respect to a wellbore includes logging well data via the tool over a period of time and measuring a lateral acceleration of the tool over the period of time with one or more accelerometers embedded in the tool. The method further includes performing double integration on an acceleration of the tool over a period of time. The method also includes obtaining a displacement of the tool over the period of time from the double integration. The method also includes fitting the displacement of the tool over the period of time to a best fit curve. The method also includes subtracting the best fit curve from the displacement of the tool over the period of time.

A method for characterizing a hydraulic fracture in a subsurface formation, includes inducing a pressure change in a well drilled through the subsurface formation. Pressure and/or a time derivative thereof is measured at a location proximate to a wellhead for a selected length of time. A conductivity of at least one fracture is determined using the measured at least one of pressure and the time derivative of pressure. A change in the determined conductivity with respect to time is determined.

Methods and systems for removing tool mode waveforms. The method may include disposing a bottom hole assembly (BHA) into a wellbore. The BHA may comprise at least one transmitter configured to transmit a pressure pulse and at least one receiver configured to record one or more waveforms. The method may further comprise performing a logging-while-drilling (LWD) operation in which the one or more waveforms are recorded with the at least one receiver, transmitting the one or more waveforms to an information handling system, removing one or more tool mode waveforms from the one or more waveforms to form an updated set of waveforms, and forming differential phase time semblance map based at least in part on the updated set of waveforms. The system may comprise the BHA and information handling system configured to remove one or more tool mode waveforms.

Enclosed herein are a method and system for reduction of a tool wave excited by a transmitter of the well logging tool. In one embodiment, a method comprises transmitting, by a primary transmitter, a primary acoustic wave into a geologic formation which excites a tool wave and a formation wave in the geologic formation, wherein the logging tool comprises a tool wave propagating factor which is different from a formation wave propagating factor; receiving, by one or more receivers, the formation wave and the tool wave; propagating waveform data associated with the received tool wave and formation wave based on a distance between the auxiliary receiver and a primary receiver; and reducing the tool wave in waveform data associated with the formation wave and the tool wave received by a primary receiver of the one or more receivers based on the propagated waveform data.