Raytheon Company

James A Nalasco

Benjamin P Dolgin

William G Suliga

John T Ishibashi

Michael A Toreno

Thomas G Pepin

Disclosed is a system and method for horizontal directional drilling (HDD). The system and method utilize predictive algorithms to both characterize the soil within the borehole and to quantify instability within the drillstring. The soil characteristics are represented by a soil coefficient (&#x3b1;) which relates the curvature of the borehole with the length of thrust of the drill rig as well as by comparison of thrust while thrusting with torque while drilling. The value of (&#x3b1;) is obtained by comparison of the historical orientation of the drilling head over the length of the borehole and the borehole shape as determined by an arbitrary navigation sensor. Drillstring instability is determined as a function of historical thrust and torque efficiencies and windup over the length of the borehole.

System and method for determining soil characteristics and drilling instability during horizontal directional drilling

Disclosed is a system and method for horizontal directional drilling (HDD). The system and method utilize predictive algorithms to both characterize the soil within the borehole and to quantify instability within the drillstring. The soil characteristics are represented by a soil coefficient (&#x3b1;), which relates the curvature of the borehole with the length of thrust of the drill rig as well as by comparison of thrust while thrusting with torque while drilling. The value of (&#x3b1;) is obtained by comparison of the historical orientation of the drilling head over the length of the borehole and the borehole shape as determined by an arbitrary navigation sensor. Drillstring instability is determined as a function of historical thrust and torque efficiencies and windup over the length of the borehole.

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Fairfax Station, VA, United States of America

James A Nalasco