Subsurface drilling tool

Abstract

An improved subsurface drill bit includes two rotatable cutters disposed between two ear portions of a shank, each of the rotatable cutters having an arcuate face and cutting elements. Cutting edges of the cutting elements, outer surfaces of the ear portions, and protrusions extending outwardly from the shank collectively define a circular configuration to prevent backflow of drilling debris and to prevent wobble of the drill bit in operation. The two rotatable cutters can have an on-load configuration in which each of the cutters is in contact with each other, and an off-load configuration in which each of the cutters is in contact with one of the ear portions. Several improved rotatable cutters are provided. The rotatable cutters can be interchangeable. The drill bit can further include an improved fluid delivery system, including multiple fluid passageways and reverse jets.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part application of U.S. application Ser. No. 14 / 290,597, filed on May 29, 2014, which claims the benefit of U.S. Provisional Appl. No. 61 / 879,131, filed on Sep. 17, 2013; and a continuation-in-part application of U.S. application Ser. No. 14 / 465,907, filed on Aug. 22, 2014, which claims the benefit of U.S. application Ser. No. 14 / 290,597 and U.S. Provisional Appl. No. 61 / 879,131, all of which are incorporated by reference herein in their entireties.FIELD OF THE DISCLOSURE[0002]The present disclosure relates in general to subsurface drilling tools and cutting elements for drill bits or other tools incorporating the same. More specifically, embodiments disclosed herein relate generally to rotatable cutting elements for rotary drill bits for deep well drilling.BACKGROUND OF THE DISCLOSURE[0003]Drill bits used to drill wellbores through earth formations generally are made within one of two broad categori...

AI Technical Summary

Benefits of technology

The aim of this patent is to create a new and improved tool for drilling hard rock formations more efficiently. The goal is to overcome the shortcomings of existing methods in the field.

Problems solved by technology

Additionally, the bit and the PDC cutters may be subjected to substantial abrasive forces.

In some instances, impact, vibration and erosive forces have caused drill bit failure due to loss of one or more cutters, or due to breakage of the blades.

Conventional polycrystalline diamond is stable at temperatures of up to 700-750° Celsius in air, above which observed increases in temperature may result in permanent damage to and structural failure of polycrystalline diamond.

Upon heating of polycrystalline diamond, the cobalt and the diamond lattice will expand at different rates, which may cause cracks to form in the diamond lattice structure and result in deterioration of the polycrystalline diamond.

Damage may also be due to graphite formation at diamond-diamond necks leading to loss of microstructural integrity and strength loss, at extremely high temperatures.

Exposure to heat (through brazing or through frictional heat generated from the contact of the cutter with the formation) can cause thermal damage to the diamond table and eventually result in the formation of cracks (due to differences in thermal expansion coefficients) which can lead to spalling of the polycrystalline diamond layer, delamination between the polycrystalline diamond and substrate, and conversion of the diamond back into graphite causing rapid abrasive wear.

As a cutting element contacts the formation, a wear flat develops and frictional heat is induced.

As the cutting element is continued to be used, the wear flat will increase in size and further induce frictional heat.

The heat may build-up that may cause failure of the cutting element due to thermal miss-match between diamond and catalyst discussed above.

In fact, sufficient backpressure created by the debris and fluid can effectively exceed the pressure provided to the wellbore by a pump, causing a “reversal” of the fluid delivery system.

The wobble can decrease drilling efficiency and increase wear on the shank of the drill bit.

However, bridge plugs are often constructed from brittle metals such as cast iron, which is not particularly conducive to milling.

The milling of the plugs can result in undesirably large chunks of the plug, which can become lodged in the lateral of the casing.

Further, milling produces undesirably high levels of torque.

In addition to not being designed for the application, the tri-cone drill bit can mechanically fail, after which one of the three cones may become lodged in the wellbore.

The speed with which the motor can drive the tri-cone bit and the weight that can be applied to the bit is limited due to the use of ball bearings in a tri-cone bit.

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