Abstract: A method for determining a shear wave velocity of a subterranean formation from a leaky shear wave arrival is disclosed. Standoff measurements are utilized to indicate the presence of leaky shear wave arrivals in the received waveforms. In one exemplary embodiment, leaky shear waves are indicated when the measured standoff distance is less than a predetermined threshold. The invention may provide for a direct determination of shear wave velocity in acoustically slow formations, thereby potentially improving accuracy as compared to prior art estimation techniques. The invention may further provide for improved power efficiency.

Abstract: A method for determining a borehole azimuth in a borehole is disclosed. In one exemplary embodiment, the method includes acquiring at least one standoff measurement and a tool azimuth measurement at substantially the same time. Such measurements are then processed, along with a lateral displacement vector of the downhole tool upon which the sensors are deployed in the borehole, to determine the borehole azimuth. The computed borehole azimuths may be advantageously correlated with logging sensor data to form a borehole image, for example, by convolving the correlated logging sensor data with a window function. As such, exemplary embodiments of this invention may provide for superior image resolution and noise rejection as compared to prior art LWD imaging techniques.

Abstract: A method for determining a borehole azimuth in a borehole is disclosed. In one exemplary embodiment, the method includes acquiring at least one standoff measurement and a tool azimuth measurement at substantially the same time. Such measurements are then processed, along with a lateral displacement vector of the downhole tool upon which the sensors are deployed in the borehole, to determine the borehole azimuth. The computed borehole azimuths may be advantageously correlated with logging sensor data to form a borehole image, for example, by convolving the correlated logging sensor data with a window function. As such, exemplary embodiments of this invention may provide for superior image resolution and noise rejection as compared to prior art LWD imaging techniques.

Abstract: A method for determining a borehole geometry parameter vector and/or lateral tool displacement vectors in a borehole is provided. The method includes acquiring at least one set of standoff measurements at a corresponding time. The method also includes processing a system of equations to determine the parameter vector and/or the lateral displacement vector(s). The system of equations may include variables representative of the parameter vector, the lateral tool displacement vector(s), and the standoff measurements. Exemplary embodiments of this invention advantageously enable the borehole parameter vector and/or the lateral displacement vector to be determined substantially contemporaneously.

Abstract: An azimuthally sensitive electromagnetic measurement tool is provided. The tool may be suitable, for example, to measure azimuthal variations of electrical properties of a subterranean formation. The tool includes a transmitter disposed to transmit electromagnetic energy into a subterranean formation and a longitudinally spaced receiver. At least one of the transmitter and the receiver includes a sector antenna. The sector antenna includes an exposed length of antenna wire that forms an arc about a portion of a circumference of the tool body. In one exemplary embodiment, the receiver includes first and second sector antennae, which, in combination, subtend a circular angle of about 360 degrees about the circumference of the tool body without substantially overlapping one another.

Abstract: Method and apparatus are provided for adjusting electromagnetic well logging data for effects of frequency dispersion. In exemplary embodiments, a model is provided for estimating an electrical property of an earth formation as a function of frequency. The model is derived, for each particular volume of interest, based on measured data obtained by employing a plurality of interrogation frequencies. Measured data may include electrical properties of the volume of interest such as conductivity and dielectric constant. The model predicts the measurements expected to be obtained by a tool employing a selected interrogation frequency, including frequencies for which no measured data are available. In one embodiment, the model may be used to adjust measured data for effects of frequency dispersion to correspond to a selected interrogation frequency, allowing the adjusted data to be more effectively correlated to logging data obtained by a different type of tool employing a different interrogation frequency.