Schlumberger Technology Corporation

Peter Hornblower

Junichi Sugiura

Maja Ignova

Steven Hough

Adam Ian Bowler

Christopher Bogath

Geoff Downton

Edward Richards

Martin Thomas Bayliss

A downhole closed loop method for controlling a curvature of a subterranean wellbore while drilling includes controlling a direction of drilling such that the drilling attitude is substantially equal to a setpoint attitude. A setpoint rate of penetration is processed in combination with a setpoint dogleg severity to compute a setpoint attitude increment. The setpoint attitude may be adjusted by the setpoint attitude increment. The setpoint attitude may be incremented at some interval to control the curvature of the wellbore while drilling.

Control of drilling curvature

Closed loop control of drilling curvature

A downhole closed loop method for controlling a drilling toolface includes measuring first and second attitudes of the subterranean borehole at corresponding first and second upper and lower survey stations. The first and second attitudes are processed downhole while drilling to compute an angle change of the subterranean borehole between the upper and lower survey stations. The computed angle change is compared with a predetermined threshold. This process may be continuously repeated while the angle change is less than the threshold. The first and second attitudes are further processed downhole to compute a toolface angle when the angle change of the subterranean borehole is greater than or equal to the threshold. The toolface angle may then be further processed to control a direction of drilling of the subterranean borehole.

Closed loop control of drilling toolface

A downhole closed loop method for controlling a curvature of a subterranean wellbore while drilling includes drilling the subterranean wellbore using a drilling tool. A set point curvature is received at a downhole controller. Sequential attitude measurements made at a single axial location on the drilling tool and a rate of penetration of drilling are processed to compute a curvature of the wellbore being drilled. The drilling direction is adjusted such that the computed curvature is substantially equal to the set point curvature.

Exhaust pressure from at least one actuator () which can tilt jointof a bottom hole assemblycan be utilized to determine the directiontiltable jointis pointing (e.g., orientation, angular displacement, and/or inclination and azimuth). In one embodiment, a known exhaust pressure can be correlated to a known orientation and/or angular displacement, and the measured exhaust pressure can be compared to the known exhaust pressure to determine the orientation and/or angular displacement. In another embodiment, the flow rate of fluid exhausted from an actuator () can be derived from the exhaust pressure. The exhaust flow rate can then be used to calculate the state of actuation, which can allow determination of the angular displacement of the tiltable joint. Orientation and/or angular displacement with respect to the bottom hole assemblycan be resolved into an inclination and azimuth with respect to a formation

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Gloucester, United Kingdom

Peter Hornblower