Smith International, Inc.

Charles R Muren

Gary Ray Portwood

Roger P Johns

Gilbert S Tyner

A roller cone drill bit is disclosed that leaves uncut a substantial formation core having a diameter from 10% to 25% of the bit gage diameter. The bit is designed to have normal size bearings, cone shell thickness and cutter protrusion to allow the use of standard drilling weights and RPM, thereby achieving a significant increase in drilling rate. When drilling abrasive formations, ultra hard cutting teeth are used in the cone apex to maintain the core diameter.

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Humble, TX, United States of America

Charles R Muren