Fixed cutter drill bit for abrasive applications

Abstract

The invention provides a fixed cutter drill bit for drilling through unconsolidated, highly abrasive formations. The bit includes a bit body having a cutting face and a side portion. The bit body comprising carbide matrix material. A plurality of blades azimuthally spaced about the cutting face and a plurality of cutters disposed along the blades. At least one gage pad is disposed along a side of the bit body and includes wear resistant gage elements formed of a material more wear resistant than the matrix material forming a portion of the gage pad. The wear resistant elements have a rounded surface and are embedded in gage pad material proximal a leading edge of the gage pad to provide a rounded wear-resistant edge or surface proximal the leading edge.

Description

BACKGROUND OF INVENTION[0001]1. Field of the Invention[0002]The invention relates to fixed cutter drill bits designed for abrasive applications, and more particularly to fixed cutter bits designed for high rate of penetration drilling in unconsolidated ultra abrasive formations.[0003]2. Background Art[0004]Different types of drill bits have been developed and found useful in different drilling environments. Bits typically used for drilling boreholes in the oil and gas industry include roller cone bits and fixed cutter. Cutting structures on bits vary depending on the type of bit and the type of formation being cut. Roller cone cutting structures typically include milled steel teeth, tungsten carbide inserts (“TCIs”), or diamond enhanced inserts (DEIs). Cutting structures for fixed cutter bits typically include polycrystalline diamond compacts (“PDCs”), diamond grit impregnated inserts (“grit hot-pressed inserts” (GHIs)), or natural diamond. The selection of a bit type and cutting st...

AI Technical Summary

Benefits of technology

[0011]In one aspect, the present invention provides a fixed cutter drill bit providing improved performance in a high rate of penetration unconsolidated abrasive drilling operation.

[0012]In one embodiment, the bit includes a bit body having a cutting face and a side portion. The bit body is formed of carbide matrix material. A plurality of blades azimuthally spaced about the cutting face and a plurality of cutters disposed along the blades. At least one gage pad is disposed along a side of the bit body and comprising wear resistant gage elements formed of a material more wear resistant than the matrix material forming a portion of the gage pad. The wear resistant elements include a rounded surface and are embedded in gage pad material proximal a leading edge of the gage pad to provide a rounded wear-resistant edge or surface proximal the leading edge.

[0013]In another embodiment, the drill bit includes a bit body, a plurality of blades, and a plurality of cutters is disposed along the blades and arranged to have an extent from a corresponding blade front face of 0.10 inches or less for a majority of the cutters. A majority of the adjacent cutters are also positioned to have spaces there between that are less than 0.25 inches. At least one gage pad is disposed along a side of the bit body. The at least one gage pad has a circumferential width that is at least about 2 inches or results in a total gage pad width equal to 30% or more of the circumference of the bit. At least one wear resistant element is disposed on the gage pad near a leading edge of the gage pad to provide wear resistant protection near the leading edge. Additionally, the bit includes at least one back reaming element positioned on the bit to back ream formation in a path of the bit as the bit is pulled from a wellbore.

Problems solved by technology

In drilling unconsolidated, ultra abrasive formations, bit life is limited due to excessive wear; therefore, bit cost has become a significant factor in the selection of bits for this environment.

Heavy oil reservoirs typically comprise unconsolidated to low compressive strength, yet highly abrasive sands that are permeated with thick, dense heavy oil.

Drill bits used in unconsolidated, ultra abrasive applications are typically damaged beyond repair after a first run due to the extreme abrasion and erosion encountered during drilling.

Fixed cutter bits are generally not used in these applications because they cost 5 to 10 times more than a comparable roller cone bit and typically become damaged beyond repair after a first run, such that their higher cost can not be justified.

Although roller cone bits have been found to be most economically feasible for unconsolidated, ultra abrasive applications, the useful life of these bits is limited.

Images