Systems, methods, and computer-readable media for directional drilling based on curvature-based feedback. In some examples, a drilling tool tracks a current position and a current attitude, determines a curvature value for a curved path that intersects the current position, tangent to the current attitude, and a curvilinear position on or substantially proximate a target wellbore path, tangent to a target attitude, generates a wellbore path based on the curvature value, and updates the current position or the current attitude based on at least one of a change in the current position or a change in the current attitude.

This disclosure is related to real-time calibration of drilling modeling programs and to the estimation of pipe stretch to perform corrections for the inclination and azimuth measurements and the estimation of pipe twist to perform corrections to the tool face setting. A measurement tool with a plurality of sensors is disposed along the drill string. Measurements are taken continuously during the drilling process from each of the sensors to determine torque, bending moment, and axial force data. This information is iteratively coupled with a mechanical torque-drag model (based on standard mechanics of deformable materials and on wellbore mechanics) to accurately estimate stretching and twisting of the drill string in real-time or near-real-time and thereby promote accurate wellbore placement.

This disclosure is related to real-time calibration of drilling modeling programs and to the estimation of pipe stretch to perform corrections for the inclination and azimuth measurements and the estimation of pipe twist to perform corrections to the tool face setting. A measurement tool with a plurality of sensors is disposed along the drill string. Measurements are taken continuously during the drilling process from each of the sensors to determine torque, bending moment, and axial force data. This information is iteratively coupled with a mechanical torque-drag model (based on standard mechanics of deformable materials and on wellbore mechanics) to accurately estimate stretching and twisting of the drill string in real-time or near-real-time and thereby promote accurate wellbore placement.

Systems and methods of optimizing a new well path using a minimum curvature method are disclosed. An arc of the new well path may include a change in curvature at a point along the length of the arc. The arc of the new well path may be determined by iteratively: selecting a length of a first arc portion of the arc; determining a length of a second arc portion of the arc according to a minimum curvature method; combining the first arc portion and the second arc portion to form an arc; determining a deviation of the arc relative to a planned well trajectory; and selecting the arc with the lowest deviation from the planned well trajectory.

A method for steering a downhole tool includes receiving an electromagnetic (EM) signal from the downhole tool. The downhole tool is in a wellbore in a formation. The EM signal comprises a gap voltage and a gap current that are measured across a gap sub in the downhole tool. The method also includes determining a gap impedance based at least partially upon the gap voltage and the gap current. The method also includes determining a first formation resistivity at a first location in the wellbore based at least partially upon the gap impedance. The method also includes steering the downhole tool based at least partially upon the first formation resistivity.

The present disclosure relates to a system, apparatus and method for guiding a drill bit based on forces applied to a drill bit, and drilling methods related to same.

The present disclosure relates to a system, apparatus and method for guiding a drill bit based on forces applied to a drill bit, and drilling methods related to same.

A Rotary Steerable System (RSS) includes a flexible collar coupled therein that reduces the stiffness of the RSS and permits a tighter turning radius to be achieved. The positioning of the flexible collar between the steering section and the controller of the RSS further improves the turning radius, and may permit a push-the-bit system to operate similar to a point-the bit system. The flexible collar permits communication therethrough between controller and the steering sections of the RSS. The RSS may be arranged as a modular system to receive various configurations of a flexible collar and may operate with no flexible collar installed. The modularity enables tuning of the stiffness of an RSS to achieve different steering objectives.

A method for directional drilling including defining, by a sliding mode controller, a sliding hypersurface for reducing a trajectory error in one or more error dimensions; determining a current trajectory error between a current trajectory of a directional drilling tool and a reference trajectory for a curved path, the current trajectory error corresponding to a current error position in the one or more error dimensions; calculating a sliding mode vector originating from the current error position and substantially conforming to the sliding hypersurface in the one or more error dimensions; determining a feedback control input for the directional drilling tool based on the sliding mode vector; instructing the directional drilling tool to generate a wellbore path according to the feedback control input; and updating the current trajectory error based on either a change in position or a change in attitude of the directional drilling tool.

A method for directional drilling including defining, by a sliding mode controller, a sliding hypersurface for reducing a trajectory error in one or more error dimensions; determining a current trajectory error between a current trajectory of a directional drilling tool and a reference trajectory for a curved path, the current trajectory error corresponding to a current error position in the one or more error dimensions; calculating a sliding mode vector originating from the current error position and substantially conforming to the sliding hypersurface in the one or more error dimensions; determining a feedback control input for the directional drilling tool based on the sliding mode vector; instructing the directional drilling tool to generate a wellbore path according to the feedback control input; and updating the current trajectory error based on either a change in position or a change in attitude of the directional drilling tool.