Schlumberger Technology Corporation

Makito Katayama

Edward Richards

Julien Steimetz

Andrew Whitmore

Zainab Orooq

Joffroy Dominique Daniel Urbain

A method for making axial magnetic field measurements in a downhole tool includes evaluating axial magnetic field measurements to determine a magnetic interference offset and removing the magnetic interference offset to obtain compensated axial magnetic field measurements.

Interference compensated axial magnetometer measurements

A gyroscope assembly is maintained in a park position during drilling activities. In the park position, a sensitive axis of a gyroscope in the gyroscope assembly is perpendicular or approximately perpendicular to a longitudinal axis of a downhole tool. Maintaining the park position during drilling activities reduces the drift bias caused by overloading the input signal of the gyroscope due to rotation of the downhole tool.

Park position for a survey tool

A method for drilling a subterranean wellbore includes rotating a bottom hole assembly (BHA) in the subterranean wellbore to drill, in which the BHA includes a drill collar, a drill bit, a roll-stabilized housing deployed in the drill collar and configured to rotate with respect to the drill collar, and triaxial accelerometer and triaxial magnetometer sets deployed in the roll-stabilized housing. Triaxial accelerometer and triaxial magnetometer measurements and a drill collar rotation rate measurement are made while the BHA rotates. A wellbore inclination and a gravity tool face of the roll-stabilized housing are computed from the triaxial accelerometer measurements. The computed inclination and gravity toolface, the triaxial magnetometer measurements, and the measured rotation rate of the drill collar are processed to compute an azimuth of the subterranean wellbore in which influences of eddy currents and magnetometer biases are accounted.

Growing community of inventors

Cheltenham, United Kingdom

Makito Katayama