PDC cutter for high compressive strength and highly abrasive formations

Abstract

A PDC cutter utilizes the combination of an elliptical shape with higher thermal resistance obtained through leaching to provide a cutter which is more effective than a cutter using either concept alone. The PDC cutter includes a tungsten carbide portion with protrusions extending from a surface thereof in a pattern. The diamond volume is mounted to the surface wherein the protrusions allow for the diamond volume to be larger about a perimeter edge of the cutter and smaller / shallower in a center region of the cutter. The protrusions providing surfaces for the diamond layer (table) to bond to the underlying tungsten carbide portion. With this configuration, diamond volume is maximized around the edge of the cutter.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] The present application claims the benefit of U.S. Provisional Application for Patent No. 60 / 751,835 filed Dec. 20, 2005, the disclosure of which is hereby incorporated by reference.BACKGROUND OF THE INVENTION [0002] 1. Technical Field of the Invention [0003] The present invention relates to a PDC cutter used for drilling boreholes into the earth. [0004] 2. Description of Related Art [0005] Drilling high compressive strength rocks that are highly abrasive has always been a challenge for PDC cutters. When a rock has a high compressive strength, high force is required for the cutter to penetrate the rock. High cutting forces cause problems. When the high cutting forces are transmitted to the drill string, drilling problems occur. For example, the drill string can buckle or bow causing unwanted deviation of the well. High forces cause problems within the cutter. The higher forces cause more frictional heating. The heating causes rapid wear ...

AI Technical Summary

Benefits of technology

[0033] While the concepts of leaching cutters and using elliptical shaped cutters have improved the performance of PDC bits, neither has been successful in drilling high compressive strength formations that are highly abrasive. The present invention utilizes the combination of elliptical shape and higher thermal resistance through leaching to provide a cutter which is more effective than a cutter using either concept alone. There appears to be a synergy between the two concepts.

[0034] In an embodiment, a PDC cutter utilizes the combination of an elliptical shape with higher thermal resistance obtained through leaching. A tungsten carbide portion includes protrusions which extend from a surface thereof in a pattern. The diamond volume is mounted to the surface wherein the protrusions allow for better attachment as well as for the diamond volume to be larger about a perimeter edge of the cutter and smaller / shallower in a center region of the cutter.

[0038] The invented configuration of PDC cutter seeks to increase drilling efficiency by the following: The shape of the PDC cutter requires less weight on bit than conventional PDC cutters, lessening wear and cracking due to frictional heating. It is composed of preferred PDC materials to increase the cutters resistance to heat. The shape of the cutter is optimized for high strength to reduce damage from high down hole forces. The shape of the cutter is optimized for easier cooling from the flow of the surrounding fluid. These combined factors enable the economical drilling of formations that were not previously drillable by PDC cutters. The PDC cutters increase the rate of penetration beyond impregnated or rock bits.

Problems solved by technology

While the concepts of leaching cutters and using elliptical shaped cutters have improved the performance of PDC bits, neither has been successful in drilling high compressive strength formations that are highly abrasive.

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