Abstract: The present disclosure relates to a method to determine a clock signal when separate clocks are used. In one embodiment, a disciplined clock system comprising an update subsystem and a synthesis subsystem is provided. A first clock phase estimate is provided to the update subsystem and used, along with the update subsystem, to determine a frequency offset estimate and a phase offset estimate. The clock signal is determining using the frequency offset estimate, the phase offset estimate, and the synthesis subsystem. Alternatively, two clocks can be synchronized by generating a signal associated with a first clock; modulating the signal; transmitting the modulated signal; receiving the modulated signal by a receiver associated with a second clock; correlating the received signal; determining the time of arrival of the received signal; determining the time difference between the two clocks; and synchronizing the two clocks.

Abstract: A technique provides a methodology for improving surveys of subterranean regions. The methodology comprises estimating macro anisotropy and an intrinsic or micro anisotropy of an overburden. A surface electromagnetic survey is conducted, and the data from the survey is inverted based on or including information gained from estimating the macro anisotropy and/or intrinsic anisotropy. A processor system can be used to conduct the inversion with the adjustments for anisotropy to improve the information provided by the survey.

Abstract: The present disclosure relates to a method to determine a clock signal when separate clocks are used. In one embodiment, a disciplined clock system comprising an update subsystem and a synthesis subsystem is provided. A first clock phase estimate is provided to the update subsystem and used, along with the update subsystem, to determine a frequency offset estimate and a phase offset estimate. The clock signal is determining using the frequency offset estimate, the phase offset estimate, and the synthesis subsystem. Alternatively, two clocks can be synchronized by generating a signal associated with a first clock; modulating the signal; transmitting the modulated signal; receiving the modulated signal by a receiver associated with a second clock; correlating the received signal; determining the time of arrival of the received signal; determining the time difference between the two clocks; and synchronizing the two clocks.

Abstract: A method to obtain gain-corrected measurements. A measurement tool having one or more arrays is provided, wherein the arrays include two co-located triaxial transmitters and two co-located triaxial receivers. Measurements are obtained using the transmitters and the receivers. Impedance matrices are formed from the obtained measurements and the impedance matrices are combined to provide gain-corrected measurements. The apparatus may alternatively be a while-drilling logging tool having one or more arrays, wherein each array comprises a transmitter, a receiver, and a buck, and wherein the signal received by the receiver is subtracted from the signal received by the buck or vice versa. A slotted shield may be incorporated into either embodiment of the tool. The slots may form one or more island elements. A material is disposed in the slots. The islands and shield body have complementary tapered sides that confine the islands within the shield body.

Abstract: A system and method to determine earth formation properties by positioning a logging tool within a wellbore in the earth formation, the logging tool having a tool rotation axis and a first, a second, and a third tilted transmitter coil, and a tilted receiver coil; rotating the logging tool about the tool rotation axis; energizing each transmitter coil; measuring a coupling signal between each transmitter coil and the receiver coil for a plurality of angles of rotation; determining a coupling tensor; and determining the earth formation properties using the coupling tensor.

Abstract: A method and system for producing look-ahead profiles measurements includes positioning an energy transmitter, such as a transmitting antenna, proximate to a borehole assembly tool. One or more energy receivers, such as receiving antennas, are positioned along a length of the borehole assembly. Next, energy is transmitted to produce look-ahead scans relative to the borehole assembly tool. Look-ahead graph data with an x-axis being a function of a time relative to the position of the borehole assembly tool is generated. The look-ahead graph is produced and displayed on a display device. The look-ahead graph may track estimated formation values based on earth models. The estimated formation values are displayed below a tool position history line that is part of the look-ahead graph. The estimated formation values in the look-ahead graph may be based on inversions of resistivity data from the look-ahead scans.

Abstract: The present disclosure relates to a method to determine a clock signal when separate clocks are used. In one embodiment, a disciplined clock system comprising an update subsystem and a synthesis subsystem is provided. A first clock phase estimate is provided to the update subsystem and used, along with the update subsystem, to determine a frequency offset estimate and a phase offset estimate. The clock signal is determining using the frequency offset estimate, the phase offset estimate, and the synthesis subsystem. Alternatively, two clocks can be synchronized by generating a signal associated with a first clock; modulating the signal; transmitting the modulated signal; receiving the modulated signal by a receiver associated with a second clock; correlating the received signal; determining the time of arrival of the received signal; determining the time difference between the two clocks; and synchronizing the two clocks.

Abstract: The present disclosure relates to a method to determine the phase of a signal when transmitter and receiver circuits use separate clocks. A discrepancy between the separate clocks is determined, as is a correction factor between the separate clocks. The phase is determined using a measured time of arrival of the signal, the determined discrepancy, and the determined correction factor. A drift factor and an expected start time of a pulse sequence may be used to determine the discrepancy. A start time of a pulse within the pulse sequence is determined and used to determine the correction factor. The method works by either absolute synchronization of the separate clocks, or by making the measurements independent of clock synchronization.

Abstract: An interactive display of results obtained from the inversion of logging data is produced by obtaining and inverting the logging data using a Monte-Carlo inversion. An interactive plot having a percentile scale plotted against a location parameter is produced and a particular percentile is selected using the interactive plot. A cross-section plot for the particular percentile using the results of the Monte-Carlo inversion is produced. The particular percentile can be a curve representing a best-fit solution or a polyline representing selected solutions. Background color/shading can be displayed on the interactive plot to indicate user-defined constraints have been applied. Uncertain features can be plotted on a corresponding cross-section display using fading. Clusters of solutions that are substantially equally likely, given the measurements at a particular drill location, can be identified and plotted.

Abstract: During a drilling operation, measured data from the drilling operation may be received with a panistic inversion and risk estimate module. The panistic inversion and risk estimate module may generate a plurality of mathematical solutions from a panistic inversion that uses the measured data and one or more earth models. The one or more earth models having various parameters may be selected prior to drilling and/or while the drilling operation occurs. For each solution of the plurality of mathematical solutions generated from the panistic inversion, the panistic inversion and risk estimate module may determine if the measured data exceeds one or more probability risk thresholds associated with the drilling operation. If the measured data exceeds the probability risk threshold associated with the drilling operation, then the panistic inversion and risk estimate module may generate an alert.

Abstract: Method and system for visualizing one or more properties of a subterranean earth formation while drilling a borehole using probability information from a modeling process. Probability waveforms based on information from a plurality of borehole stations may be plotted, either alone or superimposed onto other graphical representations, to provide a visual display that is easily interpreted by a user to make geosteering decisions. The probability waveforms include peaked sections that are proportional to the amount of uncertainty or error associated with a boundary estimate at a particular distance from an axis of the borehole. By providing a visual display of the uncertainty, a user can make better geosteering decisions.

Abstract: A method for directing bore-hole drilling in a target earth formation includes the following steps: providing drilling equipment having a bottom hole assembly that includes a controllable directional drilling subsystem, and a logging-while-drilling directional measurement tool with a look-around and look-ahead capability; determining the presence of a predetermined type of formation characteristic in the target formation; and navigating a drill path in the target formation with the drilling equipment, including receiving measurement signals from the directional measurement tool, obtaining, from the received measurement signals, indications of formation parameters with respect to the formation characteristic in the target formation, and controlling the directional drilling subsystem to drill in a direction determined as a function of the obtained indication of formation parameters.

Abstract: A method and a downhole tool determine one or more parameters of a formation traversed by a borehole where at least a portion of the formation has substantially parallel boundaries. A tool is disposed in the borehole that includes a transmitter having a dipole moment at an angle ?T with respect to a longitudinal axis of the tool, a receiver having a dipole moment at an angle ?R with respect to the longitudinal axis of the tool and a rotational position indicator. The transmitter-receiver pair transmits an electromagnetic signal while rotating the tool, receives the electromagnetic signal to produce a measured signal, and determine(s) the formation parameters for the portion of the formation having substantially parallel boundaries based on the measured signal.

Abstract: A logging tool and method to make subsurface measurements is disclosed, wherein the tool is placed within a borehole penetrating a formation. The tool has a transmitter antenna and a receiver antenna spaced apart along a longitudinal axis of the tool, and at least one of the transmitter or receiver antennas has a dipole moment that is non-coaxial with the longitudinal axis of the tool. The at least one non-coaxial antenna can rotate relative to the other antenna. Energy is transmitted from the transmitter antenna and a signal associated with the transmitted energy is measured at the receiver antenna while the at least one non-coaxial antenna rotates relative to the other antenna.

Abstract: A logging tool and method to make subsurface measurements is disclosed, wherein the tool is placed within a borehole penetrating a formation. The tool has a transmitter antenna and a receiver antenna spaced apart along a longitudinal axis of the tool, and at least one of the transmitter or receiver antennas has a dipole moment that is non-coaxial with the longitudinal axis of the tool. The at least one non-coaxial antenna can rotate relative to the other antenna. Energy is transmitted from the transmitter antenna and a signal associated with the transmitted energy is measured at the receiver antenna while the at least one non-coaxial antenna rotates relative to the other antenna.

Abstract: A resistivity tool is used with wired drill pipe and one or more wells. The resistivity tool has a transmitter, receiver modules located adjacent to the drill bit, and high sensitivity receiver modules located at greater distances from the drill bit relative to the receiver modules. The receiver modules and/or the high sensitivity receiver modules may also perform repeater functions for the wired drill pipe. The resistivity tool may provide information regarding a subsurface region of interest. The resistivity tool may be used in a system with sensors, and a distance between the sensors may be based on the type of measurement obtained by the sensors.

Abstract: A method to determine one or more parameters of a formation traversed by a borehole, at least a portion of the formation having substantially parallel boundaries, the method comprising disposing a tool in the borehole, wherein the tool includes a transmitter having a dipole moment at an angle ?T with respect to a longitudinal axis of the tool and a receiver having a dipole moment at an angle ?R with respect to the longitudinal axis of the tool, the transmitter and receiver comprising a transmitter-receiver pair; transmitting an electromagnetic signal while rotating the tool; receiving the electromagnetic signal to produce a measured signal from the transmitter-receiver pair; and determining the one or more formation parameters for the portion of the formation having substantially parallel boundaries based on the measured signal from the transmitter-receiver pair.

Abstract: The present disclosure relates to a method to determine a clock signal when separate clocks are used. In one embodiment, a disciplined clock system comprising an update subsystem and a synthesis subsystem is provided. A first clock phase estimate is provided to the update subsystem and used, along with the update subsystem, to determine a frequency offset estimate and a phase offset estimate. The clock signal is determining using the frequency offset estimate, the phase offset estimate, and the synthesis subsystem. Alternatively, two clocks can be synchronized by generating a signal associated with a first clock; modulating the signal; transmitting the modulated signal; receiving the modulated signal by a receiver associated with a second clock; correlating the received signal; determining the time of arrival of the received signal; determining the time difference between the two clocks; and synchronizing the two clocks.

Abstract: The present disclosure relates to a downhole logging tool that includes two or more tilted antennas having equal tilt angles mounted in or on the tool body. The downhole logging tool may be, for example, a wireline or while-drilling tool, and it may be an induction or propagation tool. Various symmetrized and anti-symmetrized responses may be computed and used to infer formation properties and drilling parameters.

Abstract: An embodiment of a wireless telemetry system for providing signal communication across a wired-communication gap in a bottom-hole assembly (“BHA”), the BHA having an upper portion and a lower portion separated by the wired-communication gap, includes an upper transceiver positioned in the upper portion and in signal communication with a surface telemetry system and a lower transceiver positioned in the lower portion and in signal communication with a drilling tool, the upper and the lower transceivers in signal communication with one another via wireless induction telemetry. Each transceiver may include an antenna that is positioned within the bore of a drill collar adjacent to a thinned wall section in the drill collar. The thinned wall section may include one or more of increasing an inside diameter relative to a base inside diameter of the bore and decreasing an outside diameter relative to a base outside diameter of the drill collar.