Cutting structure for single roller cone drill bit

Abstract

A roller cone drill bit is disclosed which includes a bit body adapted to be coupled to a drill string. A bearing journal depends from the bit body. A single roller cone is rotatably attached to the bearing journal. The roller cone is formed from steel and includes a plurality of cutting elements disposed at selected positions about the cone. At least one of the cutting elements has an extending body which has a first end coupled to the roller cone and a distal end extending away from the cone. The extending body is formed from steel. A super hard element is coupled to the distal end of the extending body to form a super hard cutting face for the cutting element.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 60 / 538,745 filed on Jan. 23, 2004, titled “Cutting Structure for Single Roller Cone Drill Bit,” which is now incorporated by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable. BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The invention relates generally to the field of roller cone (“rock”) bits used to drill wellbores through earth formations. More specifically, the invention is related to the structure of cutting elements used in roller cone bits having a single roller cone. [0005] 2. Background Art [0006] Roller cone drill bits are commonly used in the oil and gas industry to drill well bores through earth formations. One example of a conventional drilling system used to drill a well bore is shown in FIG. 1. The drilling system includes a drilling rig 10 used to turn...

AI Technical Summary

Problems solved by technology

One of the limitations of single cone roller bits is that the cutting elements tend to experience greater wear over time due to shearing action, compared to cutting elements on a two or three cone bits.

Shearing rock typically causes more wear on a cutting element than impacting the rock to compressively fail it.

However, as a result, the wear of the cutting elements on a single cone bit is typically not uniform.

Therefore, the cutting elements near the bottom are worn more quickly.

As cutting elements are worn and became dull, the cutting efficiency of the bit significantly declines and the effective life of the bit is unduly limited.

Moreover, the reduced wellbore diameter will decrease the flow area available for the proper circulation of drilling fluids and bit cuttings.

The use of bits, reamers, or other devices to ream the wellbore can incur substantial cost if the bottom hole assembly must be tripped in and out of the hole several times to complete the procedure.

While these methods of protection have met with some success, wear is still a problem for single cone bits.

Due to the prohibitive cost of large diamond enhanced inserts, inserts used on single cone bits have been generally small with very limited extensions from the cone surface.

The short extension of diamond enhanced inserts limits penetration of the formation and cuttings removal during drilling.

Thus, while bit life has been improved, the rate of penetration of these bits has been unduly limited.

To over come this limitation, larger diamond enhanced inserts with longer extensions are desired, but the high cost and fragility associated with these larger diamond enhanced inserts have shown them to be unsuitable and unfeasible for commercial products.

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