A flow regulation system for downlink communication includes a fixed flow valve and a variable flow valve on a discharge line. A pressure sensor is located between the fixed flow valve and the variable flow valve. A sinusoidal communication flow pattern in the drilling fluid is generated by adjusting the position of the variable flow valve based on measured valve pressures from the pressure sensor.

A device for generating oscillating signals includes an energy transfer device configured to apply an oscillating signal to a sensitive volume, and a resonant tuning circuit including the energy transfer device. The tuning circuit includes a tuning capacitor configured to cause the tuning circuit to resonate at a selected frequency, and an energy storage device. The transmitting device also includes a controller configured to apply a pulse sequence to the tuning circuit having a series of pulses, the energy storage device configured to retain electrical energy at an end of a first pulse, and discharge the electrical energy to the tuning circuit at an onset of a next pulse of the pulse sequence.

A device for generating oscillating signals includes an energy transfer device configured to apply an oscillating signal to a sensitive volume, and a resonant tuning circuit including the energy transfer device. The tuning circuit includes a tuning capacitor configured to cause the tuning circuit to resonate at a selected frequency, and an energy storage device. The transmitting device also includes a controller configured to apply a pulse sequence to the tuning circuit having a series of pulses, the energy storage device configured to retain electrical energy at an end of a first pulse, and discharge the electrical energy to the tuning circuit at an onset of a next pulse of the pulse sequence.

A method for obtaining accuracy gravity coefficients out of three orthogonally oriented accelerometer devices and a thermometer by computing, using a pre-programmed micro-control unit processor, temperature errors, bias error coefficients, sensitivity error coefficients, and orthogonality error coefficients during measurement while drilling operations. Particularly, the method uses voltage data values of the three orthogonally oriented accelerometers to compute said error coefficients which provides for zero-error positioning of the MWD tool during long-term downhole surveying as well as while facing high-shock, vibrations, and high temperatures.

A method for obtaining accuracy gravity coefficients out of three orthogonally oriented accelerometer devices and a thermometer by computing, using a pre-programmed micro-control unit processor, temperature errors, bias error coefficients, sensitivity error coefficients, and orthogonality error coefficients during measurement while drilling operations. Particularly, the method uses voltage data values of the three orthogonally oriented accelerometers to compute said error coefficients which provides for zero-error positioning of the MWD tool during long-term downhole surveying as well as while facing high-shock, vibrations, and high temperatures.

Methods and systems for generating pulses in drilling fluid are described. The methods include driving rotation of a rotor relative to a stator of a pulser assembly in an oscillatory manner. The oscillatory manner includes rotating an obstructing element from a middle position to a first blocking angle position and rotating the obstructing element from the first blocking angle position to a second blocking angle position such that selective obstruction occurs. Rotation of the at least one obstructing element selectively obstructs a stator flow passage when drilling fluid is flowing through the drill string to generate a pressure pulse in the drilling fluid and the oscillatory manner is an oscillation of the obstructing element between the first blocking angle position and the second blocking angle position such that a single oscillation is between two obstructed states of the stator flow passage.

Methods and systems for generating pulses in drilling fluid are described. The methods include driving rotation of a rotor relative to a stator of a pulser assembly in an oscillatory manner. The oscillatory manner includes rotating an obstructing element from a middle position to a first blocking angle position and rotating the obstructing element from the first blocking angle position to a second blocking angle position such that selective obstruction occurs. Rotation of the at least one obstructing element selectively obstructs a stator flow passage when drilling fluid is flowing through the drill string to generate a pressure pulse in the drilling fluid and the oscillatory manner is an oscillation of the obstructing element between the first blocking angle position and the second blocking angle position such that a single oscillation is between two obstructed states of the stator flow passage.

Downhole telemetry systems and related methods adaptively compensate for channel non-linearity effects. To compensate for channel non-linearity, the optimum signal generation parameters are determined that produce the desired modulated pressure variation at the surface. The signal generation parameters are optimized to minimize the discrepancy between the surface detected pressure signal and the intended signal. The mud propagation channel is first estimated in light of the known modulation scheme under an ideal linear-time-invariant channel assumption. The estimated channel is used to synthesize the modulated pressure signal undergoing the mud propagation given the initial signal generation parameters. The method then varies the synthesized signal generation parameters to search for the optimal signal generation parameters. The optimal signal generation parameters are then sent over downlink channel to the downhole pulser, which is ultimately used to generate the pulse waveform.

Downhole telemetry systems and related methods adaptively compensate for channel non-linearity effects. To compensate for channel non-linearity, the optimum signal generation parameters are determined that produce the desired modulated pressure variation at the surface. The signal generation parameters are optimized to minimize the discrepancy between the surface detected pressure signal and the intended signal. The mud propagation channel is first estimated in light of the known modulation scheme under an ideal linear-time-invariant channel assumption. The estimated channel is used to synthesize the modulated pressure signal undergoing the mud propagation given the initial signal generation parameters. The method then varies the synthesized signal generation parameters to search for the optimal signal generation parameters. The optimal signal generation parameters are then sent over downlink channel to the downhole pulser, which is ultimately used to generate the pulse waveform.

A servo valve in a servo pulser used to restrict flow to a larger main valve includes external stops on a housing to define rotational starting/stopping points and sweep zones for a servo rotor having digits for contacting the stops. The digits extend longitudinally away from the servo valve seat and extend into the sweep zones. Interaction between the stops and the digits in the sweep zones limit rotation of the rotor to a swept arc between the stops. The servo pulser rotor oscillates between stopping points in alternating clockwise/counterclockwise sweeps. Each sweep in a given direction creates one full pulse: closed, open, and closed. The servo pulser carries out a feedback/decision loop between hydraulic pulses (and sweeps) that receives information on one or more previous pulses and calculates how fast or slow it should drive the servo rotor for the current pulse.