Abstract: A method for determining a formation shear wave velocity for a subterranean formation includes propagating a multi-pole acoustic signal in a borehole using an acoustic transmitter and receiving an acoustic waveform from the multi-pole acoustic signal at one or more receivers deployed at the same circumferential position as the transmitter. The method further includes processing the acoustic waveform to determine a borehole guided wave velocity and processing the borehole guided wave velocity to determine the shear wave velocity of the subterranean formation. Isolation, suppression or enhancement of any particular harmonics of the acoustic signal is not required.

Abstract: A method for estimating an azimuthal dependence of a parameter of a borehole using logging sensor measurements acquired as a function of azimuth of the logging sensors is provided. The method includes acquiring at least one logging sensor measurement and a corresponding azimuth from a downhole tool. The method further includes processing a convolution of the logging sensor measurement and corresponding azimuth with a predetermined filter to determine convolved logging sensor data for at least one azimuthal position. Certain embodiments of this invention may be advantageously utilized in LWD imaging applications to provide for superior image resolution and noise rejection as compared to prior art imaging techniques.

Abstract: A method for locating casing string joints using a measurement while drilling tool is disclosed. The method includes deploying an MWD tool in a wellbore and measuring the magnetic field along a length of the wellbore. Changes in the magnetic field along the length of the wellbore are evaluated to determine the location of at least one casing joint. Embodiments of this invention may be advantageously utilized, for example, in sidetracking operations to avoid milling through a casing joint. Use of this invention may obviate the need for a separate wireline run to locate the casing joints.

Abstract: A formation fluid sampling tool including at least one sample tank mounted in a tool collar. The tool collar includes a through bore and is disposed to be operatively coupled with a drill string such that each sample tank may receive a correspondingly preselected formation fluid sample without removing the drill string from a well bore. At least one of the sample tanks further includes an internal fluid separator movably disposed therein. The separator separates a sample chamber from a pressure balancing chamber in the sample tank. The pressure balancing chamber is disposed to be in fluid communication with drilling fluid exterior thereto. The sampling tool further includes a sample inlet port connected to the sample chamber by an inlet passageway.

Abstract: A multiple contact electrical connector for interconnecting multiple power and/or communication transmission lines is provided. The invention is particularly useful in wet environments. The electrical connector includes male and female connector assemblies. A male pin assembly having a plurality of annular contacts is configured to repeatedly engage and disengage with a female socket assembly having a corresponding plurality of ring contact assemblies. Various exemplary embodiments further include retractable members deployed for sealingly isolating the annular contacts and the ring contact assemblies from fluids exterior to the male and female connector assemblies.

Abstract: An acoustic sensor for use in a downhole measurement tool is provided. The acoustic sensor includes a piezoelectric transducer and a matching layer assembly having at least one matching layer and a barrier layer. In various exemplary embodiments, the at least one matching layer includes first and second matching layers formed from a glass ceramic work piece and the barrier layer includes corrugated titanium. Exemplary embodiments of this invention may advantageously withstand the extreme temperatures, pressures, and mechanical shocks frequent in downhole environments and thus may exhibit improved reliability. A method for fabricating an acoustic sensor is also provided.

Abstract: A method for magnetizing a wellbore tubular is disclosed. The method includes magnetizing a wellbore tubular at three or more discrete locations on the tubular. In exemplary embodiments the magnetized wellbore tubular includes at least one pair of opposing magnetic poles located between longitudinally opposed ends of the tubular. Wellbore tubulars magnetized in accordance with this invention may be coupled to one another to provide a magnetic profile about a section of a casing string. Passive ranging measurements of the magnetic field about the casing string may be utilized to survey and guide drilling of a twin well. Such an approach advantageously obviates the need for simultaneous access to both wells.

Abstract: A method for determining a formation shear wave velocity for a subterranean formation includes propagating a multi-pole acoustic signal in a borehole using an acoustic transmitter and receiving an acoustic waveform from the multi-pole acoustic signal at one or more receivers deployed at the same circumferential position as the transmitter. The method further includes processing the acoustic waveform to determine a borehole guided wave velocity and processing the borehole guided wave velocity to determine the shear wave velocity of the subterranean formation. Isolation, suppression or enhancement of any particular harmonics of the acoustic signal is not required.

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 formation shear wave velocity for a subterranean formation is provided. The method includes propagating a multi-pole acoustic signal in a borehole using an acoustic transmitter and receiving an acoustic waveform from the multi-pole acoustic signal at at least one receiver. The method further includes processing the acoustic waveform to determine a borehole guided wave velocity and processing the borehole guided wave velocity to determine the shear wave velocity of the subterranean formation. Isolation, suppression or enhancement of any particular harmonics of the acoustic signal is not required.

Abstract: An acoustic sensor for use in a downhole measurement tool is provided. The acoustic sensor includes a piezo-composite transducer element. In various exemplary embodiments, the acoustic sensor further includes a composite backing layer, at least one matching layer, and a barrier layer deployed at an outermost surface of the sensor. Exemplary embodiments of this invention may advantageously withstand the extreme temperatures, pressures, and mechanical shocks frequent in downhole environments and thus may exhibit improved reliability. Exemplary embodiment of this invention may further provide improved signal to noise characteristics. Methods for fabricating acoustic sensors and downhole measurement tools are also provided.

Abstract: A method for estimating an azimuthal dependence of a parameter of a borehole using logging sensor measurements acquired as a function of azimuth of the logging sensors is provided. The method includes acquiring at least one logging sensor measurement and a corresponding azimuth from a downhole tool. The method further includes processing a convolution of the logging sensor measurement and corresponding azimuth with a predetermined window function to determine convolved logging sensor data for at least one azimuthal position. Certain embodiments of this invention may be advantageously utilized in LWD imaging applications to provide for superior image resolution and noise rejection as compared to prior art imaging techniques.

Abstract: Various apparatus and methods of supplying regulated battery power to an electrical device, such as a downhole tool, are provided. In one aspect, a method of providing power to an electrical device is provided that includes providing a plurality of batteries and providing a plurality of controllable regulators for regulating the power output of the plurality of batteries. The plurality of controllable regulators is set so that power is drawn from a minimum number of the plurality of batteries necessary to satisfy demand from the electrical device. The electrical device is enabled to periodically draw power from and thereby depassivate each of the plurality of batteries.

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.

Abstract: A method for surveying a borehole is disclosed which uses first and second gravity measurement devices disposed at corresponding first and second positions in the borehole and a supplemental reference measurement device disposed at the first position. Exemplary supplemental reference measurement devices include magnetometers and gyroscopes. The method includes determining a reference borehole azimuth at the first position using the supplemental reference measurement device, determining a change in borehole azimuth between the first and second positions using the first and second gravity measurement devices and determining the borehole azimuth at the second position by applying the change in borehole azimuth the reference azimuth. A system adapted to execute the disclosed method and a computer system including computer-readable logic configured to instruct a processor to execute the disclosed method are also provided.

Abstract: An acoustic sensor for use in a downhole measurement tool is provided. The acoustic sensor includes a piezoelectric transducer and a backing layer having at least one powder material disposed in an elastomeric matrix material. In various exemplary embodiments, the backing layer includes first and second tungsten powders disposed in a fluoroelastomer matrix material. Exemplary embodiments of this invention may advantageously withstand the extreme temperatures, pressures, and mechanical shocks frequent in downhole environments and thus may exhibit improved reliability. A method for fabricating an acoustic sensor is also provided.

Abstract: A method for surveying a borehole is provided. The method includes providing a tool having a magnetic field measurement device disposed thereon and positioning the tool in a borehole. Magnetic interference vectors are determined at at least two positions in the borehole by comparing the measured magnetic fields at those positions with a known magnetic field of the earth. The magnetic interference vectors indicate a direction to a target subterranean structure. Various embodiments of the invention compare the directions to the target subterranean structure with a historical survey thereof, so as to determine a distance between the borehole and the subterranean structure and an azimuth of the borehole. The surveying methodology of this invention may advantageously improve borehole surveying data obtained, for example, in relief well and/or well twinning drilling applications.

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: A connector assembly for connecting with a rotatable shaft is provided. The connector assembly includes a mating sleeve threadably coupleable about the shaft and a center sleeve sized and shaped for deployment between the shaft and the mating sleeve. The center sleeve includes pluralities of splines formed on inner and outer surfaces thereof. The splines on the inner surface of the center sleeve are engageable with splines on the outer surface of the shaft and the splines on the outer surface of the center sleeve are engageable with splines on the inner surface of the mating sleeve. Exemplary embodiments of this invention are useful in downhole tools to reduce make-up torque requirements of the mating sleeve, and therefore may advantageously increase the cyclic torsional and/or bending load capacity of the shaft, while also increasing the total torsional load capacity of the connection.

Abstract: A method for surveying a subterranean borehole is provided. The method includes determining tool face angles at first and second longitudinal positions in the borehole. The method further includes processing the tool face angles to determine a change in borehole azimuth between the first and second positions. Exemplary embodiments of this invention provide a direct mathematical solution for the change in azimuth and therefore provide for improved accuracy and reliability of azimuth determination (as compared to the prior art) over nearly the entire range of possible borehole inclination, azimuth, tool face, and dogleg values.