Abstract: A wireless communications system for a downhole drilling operation comprises a drill string, surface communications equipment, and a downhole telemetry tool. The surface communications equipment comprises a surface EM communications module with an EM downlink transmitter configured to transmit through at least a portion of the drill string an EM downlink transmission at a frequency between 0.5 Hz and 180 kHz. The downhole telemetry tool is mountable to a drill string and has a downhole electromagnetic (EM) communications unit with an EM downlink receiver configured to receive the EM downlink transmission. The downhole EM communications unit can further comprise an EM uplink transmitter configured to transmit an EM uplink transmission at a frequency GO between 0.5 Hz and 180 kHz, in which case the surface EM communications module further comprises an EM uplink receiver configured to receive the EM uplink transmission.

Abstract: A downhole system comprises a main sensor, such as a gamma sensor, and a backup sensor. The backup sensor may be of a different type from the main sensor. In some embodiments the backup sensor is a high reliability sensor that may have a different sensitivity from the main sensor. The system operates both the main and backup sensors and generates calibration data for the backup sensor. If the main sensor fails the calibration data may be applied to process data from the backup sensor to yield an estimate of the data that the main sensor would have yielded if it had remained operational. The calibration data may compensate for temperature variations and/or temporal drift, for example.

Abstract: Method and apparatus for transmitting data to or from a downhole tool while the tool is at or near the surface using a wireless data link. A downhole tool comprising a gap sub having a tubular section with first and second longitudinally spaced-apart electrically-conducting parts that are electrically isolated from each other. An electromagnetic telemetry transmitter is connected to apply a potential difference between the first and second electrically conductive parts. A single-wire bus provides a data connection between one of the first and second electrically conductive parts and a data processor.

Abstract: Data is communicated from sensors at a downhole location near a drill bit to surface equipment. Communication to the surface equipment may be direct or may pass through a series of nodes. The nodes in some cases are intelligently reconfigured to achieve desired data rates, achieve power management goals, and/or compensate for failed nodes.

Abstract: Data is communicated from sensors at a downhole location near a drill bit to surface equipment. Communication to the surface equipment may be direct or may pass through a series of nodes. The nodes in some cases are intelligently reconfigured to achieve desired data rates, achieve power management goals, and/or compensate for failed nodes.

Abstract: A downhole system comprises a main sensor, such as a gamma sensor, and a backup sensor. The backup sensor may be of a different type from the main sensor. In some embodiments the backup sensor is a high reliability sensor that may have a different sensitivity from the main sensor. The system operates both the main and backup sensors and generates calibration data for the backup sensor. If the main sensor fails the calibration data may be applied to process data from the backup sensor to yield an estimate of the data that the main sensor would have yielded if it had remained operational. The calibration data may compensate for temperature variations and/or temporal drift, for example.

Abstract: Data is communicated from sensors at a downhole location near a drill bit to surface equipment. Communication to the surface equipment may be direct or may pass through a series of nodes. The nodes in some cases are intelligently reconfigured to achieve desired data rates, achieve power management goals, and/or compensate for failed nodes.

Abstract: A downhole system comprises a main sensor, such as a gamma sensor, and a backup sensor. The backup sensor may be of a different type from the main sensor. In some embodiments the backup sensor is a high reliability sensor that may have a different sensitivity from the main sensor. The system operates both the main and backup sensors and generates calibration data for the backup sensor. If the main sensor fails the calibration data may be applied to process data from the backup sensor to yield an estimate of the data that the main sensor would have yielded if it had remained operational. The calibration data may compensate for temperature variations and/or temporal drift, for example.

Abstract: A telemetry method transmits data by MP telemetry to a telemetry relay system which retransmits the data by EM telemetry. The method avoids the need to incorporate MP telemetry pressure transducers into rig equipment and permits telemetry from regions unfavorable for EM telemetry because of depth and/or characteristics surrounding formations.

Abstract: Method and apparatus for transmitting data to or from a downhole tool while the tool is at or near the surface using a wireless data link. A downhole tool comprising a gap sub having a tubular section with first and second longitudinally spaced-apart electrically-conducting parts that are electrically isolated from each other. An electromagnetic telemetry transmitter is connected to apply a potential difference between the first and second electrically conductive parts. A single-wire bus provides a data connection between one of the first and second electrically conductive parts and a data processor.

Abstract: A telemetry method transmits data by MP telemetry to a telemetry relay system which retransmits the data by EM telemetry. The method avoids the need to incorporate MP telemetry pressure transducers into rig equipment and permits telemetry from regions unfavourable for EM telemetry because of depth and/or characteristics surrounding formations.

Abstract: Data is communicated from sensors at a downhole location near a drill bit to surface equipment. Communication to the surface equipment may be direct or may pass through a series of nodes. The nodes in some cases are intelligently reconfigured to achieve desired data rates, achieve power management goals, and/or compensate for failed nodes.

Abstract: A downhole system comprises a main sensor, such as a gamma sensor, and a backup sensor. The backup sensor may be of a different type from the main sensor. In some embodiments the backup sensor is a high reliability sensor that may have a different sensitivity from the main sensor. The system operates both the main and backup sensors and generates calibration data for the backup sensor. If the main sensor fails the calibration data may be applied to process data from the backup sensor to yield an estimate of the data that the main sensor would have yielded if it had remained operational. The calibration data may compensate for temperature variations and/or temporal drift, for example.

Abstract: A data logger comprising a first data store, a second data store and a controller connected to receive output from a temperature sensor indicating a temperature of the first data store. The controller may be configured to write data to the first data store and to switch to writing the data on the second data store if the indicated temperature of the first data store exceeds a first threshold temperature. The first and second data stores may be of different types. Upon the temperature of the first data store transitioning from above the first threshold to below the first threshold, the controller may be configured to copy any data recorded in the second data store to the first data store.