The present disclosure belongs to the technical field of an ultrasonic sound field measuring system, and relates to a manual acoustic axis aligning method for an ultrasonic sound field measuring system. The method comprises: obtaining an intersection between a current acoustic axis and a plane by scanning two detection planes, and calculating an inclination angle of the current acoustic axis; judging whether the inclination angle is less than an adjustment threshold. The method does not depend on the specific mechanical implementation of adjusting an acoustic axis angle. The iterative algorithm combined with geometric information can converge quickly. The criterion of intersection between the acoustic axis and the plane used is not limited to the amplitude criterion, and other criteria can be introduced by increasing the distance between two planes to increase the robustness of measuring the acoustic axis angle.

Systems for synchronizing downhole subs are disclosed. Some system embodiments may include a first downhole sub including a clock signal generator configured to generate an unmodified clock signal. The first downhole sub may also include a modification circuit configured to modify the clock signal. The system may also include a second downhole sub comprising a phase-locked loop circuit configured to receive as input the modified clock signal and output a second clock signal synchronous with the unmodified clock signal.

Systems for synchronizing downhole subs are disclosed. Some system embodiments may include a first downhole sub including a clock signal generator configured to generate an unmodified clock signal. The first downhole sub may also include a modification circuit configured to modify the clock signal. The system may also include a second downhole sub comprising a phase-locked loop circuit configured to receive as input the modified clock signal and output a second clock signal synchronous with the unmodified clock signal.

A method for obtaining gain corrected triaxial electromagnetic propagation measurements with an offset correction includes deploying an electromagnetic logging tool in a subterranean borehole. The logging tool includes at least first and second axially spaced triaxial transmitters and at least first and second axially spaced triaxial receivers. A plurality of full tensor voltage measurements may be acquired and processed tensor term by tensor term to obtain a full tensor, gain corrected quantity. The processing may optionally include (i) removing a full tensor voltage offset from the acquired full tensor voltage measurements to obtain a corresponding plurality of offset corrected voltage tensors and (ii) processing the offset corrected voltage tensor term by tensor term to obtain the full tensor, gain and offset corrected quantity.

A method for obtaining gain corrected triaxial electromagnetic propagation measurements with an offset correction includes deploying an electromagnetic logging tool in a subterranean borehole. The logging tool includes at least first and second axially spaced triaxial transmitters and at least first and second axially spaced triaxial receivers. A plurality of full tensor voltage measurements may be acquired and processed tensor term by tensor term to obtain a full tensor, gain corrected quantity. The processing may optionally include (i) removing a full tensor voltage offset from the acquired full tensor voltage measurements to obtain a corresponding plurality of offset corrected voltage tensors and (ii) processing the offset corrected voltage tensor term by tensor term to obtain the full tensor, gain and offset corrected quantity.

A system method and computer-readable medium for correcting measurements obtained by a down hole tool for residual measurement errors is disclosed. A down hole tool having at least two directional field sensors is disposed in a borehole. The at least two directional sensors are substantially orthogonal to each other and to a longitudinal axis of the down hole tool. Measurements are obtained from the at least two directional sensors during rotation of the tool by at least 360 degrees around the longitudinal axis of the tool. Residual measurement errors are determined for the obtained measurements, and a quality level of the determined residual measurement errors selected. The determined residual measurement errors are applied to the obtained measurements when the determined residual measurement errors are consistent with the selected quality level. In various embodiments, the residual measurement errors are reduced from a first value that does not match the selected quality level to a second value that are consistent with the selected quality level.

A system method and computer-readable medium for correcting measurements obtained by a down hole tool for residual measurement errors is disclosed. A down hole tool having at least two directional field sensors is disposed in a borehole. The at least two directional sensors are substantially orthogonal to each other and to a longitudinal axis of the down hole tool. Measurements are obtained from the at least two directional sensors during rotation of the tool by at least 360 degrees around the longitudinal axis of the tool. Residual measurement errors are determined for the obtained measurements, and a quality level of the determined residual measurement errors selected. The determined residual measurement errors are applied to the obtained measurements when the determined residual measurement errors are consistent with the selected quality level. In various embodiments, the residual measurement errors are reduced from a first value that does not match the selected quality level to a second value that are consistent with the selected quality level.

Apparatus, systems, and methods are disclosed. In some embodiments, an apparatus comprises a stabilizer element attached to a downhole tool housing. The stabilizer element includes at least a portion of a surface that is not parallel to a longitudinal axis of the tool housing, and that does not contact a borehole wall during operation. An electrode element is attached to the portion of the surface.

The quality of ping-based ultrasound imaging is dependent on the accuracy of information describing the precise acoustic position of transmitting and receiving transducer elements. Improving the quality of transducer element position data can substantially improve the quality of ping-based ultrasound images, particularly those obtained using a multiple aperture ultrasound imaging probe, i.e., a probe with a total aperture greater than any anticipated maximum coherent aperture width. Various systems and methods for calibrating element position data for a probe are described.

An apparatus. The apparatus includes a body and a plurality of control surfaces attached to the body. A first control surface is configured to control an ascent and descent of the apparatus, responsive to ascent/descent control information. A second control surface is configured to control a roll of the apparatus responsive to roll control information, and a third control surface is configured to control a yaw of the apparatus responsive to yaw control information. The apparatus further includes a releasable first docking fixture attached to the body, the first docking fixture configured to engage a second docking fixture on a payload.