Abstract: Aspects of this invention include a rotary steerable steering tool having a sensor arrangement for measuring downhole dynamic conditions. Rotary steerable tools in accordance with this invention include a rotation rate measurement device disposed to measure a difference in rotation rates between a drive shaft and an outer, substantially non-rotating housing. A controller is configured to determine a stick/slip parameter from the rotation rate measurements. Exemplary embodiments may also optionally include a tri-axial accelerometer arrangement deployed in the housing for measuring lateral vibrations and bit bounce. Downhole measurement of stick/slip and other vibration components during drilling advantageously enables corrective measures to be implemented when dangerous dynamic conditions are encountered.

Abstract: A method for forming a borehole image of an azimuthally sensitive borehole or formation parameter is disclosed. Such a borehole image may be formed, for example, by processing logging sensor data with a predetermined sensor response function (also referred to herein as a probability density function) to acquire probabilistically distributed sensor data. The sensor data may be distributed in either one-dimension (azimuthal) or two-dimensions (azimuthal and axial). Certain embodiments of this invention may be advantageously utilized in LWD imaging applications and provide for superior image resolution and noise rejection as compared to prior art binning techniques. Exemplary embodiments of the invention also advantageously conserve logging sensor data such that integration of the distributed data over the entire circumference of the tool provides a non-azimuthally sensitive logging measurement.

Abstract: A steering tool has a controller configured to provide closed-loop control of blade pressure and position. In one embodiment, the controller is configured to execute a directional control methodology in which the drilling direction is controlled via control of the blade position. The pressure in each blade is further controlled within a predetermined range of pressures. This embodiment tends to prevent excessive borehole friction while at the same time reducing undesirable rotation of the blade housing. In another embodiment, the controller is configured to correlate blade pressure measurements and blade position measurements during drilling. The correlation is utilized as part of a secondary directional control scheme in the event of a downhole failure of a blade position and/or pressure sensor. This embodiment tends to provide a stable and reliable backup directional control mechanism in the event a sensor failure and therefore may save considerable rig time.

Abstract: Aspects of this invention include a downhole tool and method for making a physical caliper measurement of a subterranean borehole. The tool is configured to make the physical borehole caliper measurement only when the measured pressure in each of three or more outwardly extendable blades is greater than a predetermined threshold pressure. Blade positions are measured and the borehole caliper calculated only when the pressure in each of the blades exceeds the threshold. Exemplary embodiments of the invention enable physical caliper measurements to be made with increased accuracy with each of the blades making firm contact with the borehole wall. Methods in accordance with the invention are especially well suited for use in directional drilling applications in that they tend to enable accurate caliper measurements to be made without repositioning the steering tool in the borehole.

Abstract: Aspects of this invention include a downhole assembly having a non-contact, capacitive coupling including first and second transceivers deployed in corresponding first and second downhole tool members. The capacitive coupling is disposed to transfer electrical signals between the first and second transceivers. In one exemplary embodiment, the capacitive coupling is configured to transfer data and power between a substantially non-rotating tool member and a rotating tool member, for example, the shaft and blade housing in a steering tool. Exemplary embodiments of this invention provide a non-contact, high-speed data communication channel between first and second members of a downhole assembly. Moreover, exemplary embodiments of the invention also provide for simultaneous non-contact transmission of electrical power between the first and second tool members.

Abstract: A method for forming a borehole image of an azimuthally sensitive borehole or formation parameter is disclosed. Such a borehole image may be formed, for example, by processing logging sensor data with a predetermined sensor response function (also referred to herein as a probability density function) to acquire probabilistically distributed sensor data. The sensor data may be distributed in either one-dimension (azimuthal) or two-dimensions (azimuthal and axial). Certain embodiments of this invention may be advantageously utilized in LWD imaging applications and provide for superior image resolution and noise rejection as compared to prior art binning techniques. Exemplary embodiments of the invention also advantageously conserve logging sensor data such that integration of the distributed data over the entire circumference of the tool provides a non-azimuthally sensitive logging measurement.

Abstract: Aspects of this invention include a steering tool having a controller configured to provide closed-loop control of hydraulic fluid pressure. In one exemplary embodiment, closed-loop control of a system (reservoir) pressure may be provided. In another embodiment, closed-loop control of a blade pressure may be provided while the blade remains substantially locked at a predetermined position. Other exemplary embodiments may incorporate rule-based-intelligence such that pressure control thresholds may be determined based on various measured and/or predetermined downhole parameters. The invention tends to reduce the friction (drag) between the blades and the borehole wall and thereby also tends to improve drilling rates. Moreover, the invention also tends to improve the service life and reliability of downhole steering tools.

Abstract: Aspects of this invention include methods for surveying a subterranean borehole. In one exemplary aspect, a change in borehole azimuth between first and second longitudinally spaced gravity measurement sensors may be determined directly from gravity measurements made by the sensors and a measured angular position between the sensors. The gravity measurement sensors are typically disposed to rotate freely with respect to one another about a longitudinal axis of the borehole. Gravity MWD measurements in accordance with the present invention may be advantageously made without imposing any relative rotational constraints on first and second gravity sensor sets. The present invention also advantageously provides for downhole processing of the change in azimuth between the first and second gravity sensor sets. As such, Gravity MWD measurements in accordance with this invention may be advantageously utilized in closed-loop steering control methods.

Abstract: Aspects of this invention include a downhole tool having an angular position sensor disposed to measure the relative angular position between first and second members disposed to rotate about a common axis. A plurality of magnetic field sensors are deployed about the second member and disposed to measure magnetic flux emanating from first and second magnets deployed on the first member. A controller is programmed to determine the relative angular position based on magnetic measurements made by the magnetic field sensors. In a one exemplary embodiment, a downhole steering tool includes first and second magnets circumferentially spaced on the shaft and a plurality of magnetic field sensors deployed about the housing.

Abstract: Aspects of this invention include a downhole tool (such as a steering tool) including first and second sensor sets for measuring substantially instantaneous drill string rotation rates. Each of the sensor sets includes at least one accelerometer disposed to measure cross-axial acceleration components. Embodiments of this invention advantageously enable gravitational and tool shock/vibration acceleration components to be cancelled out, thereby improving accuracy. Moreover, exemplary embodiments of this enable stick/slip conditions to be detected and accommodated.

Abstract: Aspects of this invention include a downhole tool having first and second members disposed to translate substantially linearly with respect to one another. A magnet is deployed on the first member and a plurality of magnetic field sensors is deployed on the second member. The magnetic field sensors are spaced in a direction substantially parallel with a direction of translation between the first and second members. The tool typically further includes a controller disposed to determine a linear position of the first and second members with respect to one another from magnetic flux measurements made at the magnetic field sensors. Exemplary position sensor embodiments of the present invention are non-contact and therefore are not typically subject to mechanical wear. Embodiments of the invention therefore tend to advantageously provide for accurate and reliable linear position measurements.

Abstract: Aspects of this invention include a steering tool having a controller configured to provide closed-loop control of hydraulic fluid pressure. In one exemplary embodiment, closed-loop control of a system (reservoir) pressure may be provided. In another embodiment, closed-loop control of a blade pressure may be provided while the blade remains substantially locked at a predetermined position. Other exemplary embodiments may incorporate rule-based-intelligence such that pressure control thresholds may be determined based on various measured and/or predetermined downhole parameters. The invention tends to reduce the friction (drag) between the blades and the borehole wall and thereby also tends to improve drilling rates. Moreover, the invention also tends to improve the service life and reliability of downhole steering tools.

Abstract: Aspects of this invention include a rotary steerable steering tool having a sensor arrangement for measuring downhole dynamic conditions. Rotary steerable tools in accordance with this invention include a rotation rate measurement device disposed to measure a difference in rotation rates between a drive shaft and an outer, substantially non-rotating housing. A controller is configured to determine a stick/slip parameter from the rotation rate measurements. Exemplary embodiments may also optionally include a tri-axial accelerometer arrangement deployed in the housing for measuring lateral vibrations and bit bounce. Downhole measurement of stick/slip and other vibration components during drilling advantageously enables corrective measures to be implemented when dangerous dynamic conditions are encountered.

Abstract: A method for communicating with a downhole tool located in a subterranean borehole is disclosed. Exemplary embodiments of the method include encoding data and/or commands in a sequence of varying drill string rotation rates and drilling fluid flow rates. The varying rotation rates and flow rates are measured downhole and processed to decode the data and/or the commands. In one exemplary embodiment, commands in the form of relative changes to current steering tool offset and tool face settings are encoded and transmitted downhole. Such commands may then be executed, for example, to change the steering tool settings and thus the direction of drilling. Exemplary embodiments of this invention advantageously provide for quick and accurate communication with a downhole tool.

Abstract: Aspects of this invention include a downhole tool (such as a steering tool) including first and second sensor sets for measuring substantially instantaneous drill string rotation rates. Each of the sensor sets includes at least one accelerometer disposed to measure cross-axial acceleration components. Embodiments of this invention advantageously enable gravitational and tool shock/vibration acceleration components to be cancelled out, thereby improving accuracy. Moreover, exemplary embodiments of this enable stick/slip conditions to be detected and accommodated.

Abstract: A method for communicating with a downhole tool located in a subterranean borehole is disclosed. Exemplary embodiments of the method include encoding data and/or commands in a sequence of varying drill string rotation rates and drilling fluid flow rates. The varying rotation rates and flow rates are measured downhole and processed to decode the data and/or the commands. In one exemplary embodiment, commands in the form of relative changes to current steering tool offset and tool face settings are encoded and transmitted downhole. Such commands may then be executed, for example, to change the steering tool settings and thus the direction of drilling. Exemplary embodiments of this invention advantageously provide for quick and accurate communication with a downhole tool.