An apparatus for boring a wellbore, including a bit body having a first end, an inner cavity, and a second end. The first end is connected to a workstring that is configured to deliver a rotational force to the bit body. The inner cavity contains a profile having a first radial cam surface. The second end includes a working face containing a cutting member. The apparatus also includes a pilot bit rotatively connected within the inner cavity. A second radial cam surface is contained on a first end of the pilot bit. The first and second radial cam surfaces are operatively configured to deliver a hammering force. A second end of the pilot bit may include an engaging surface configured to engage a formation surrounding the wellbore. The bit body rotates relative to the pilot bit.

A hybrid bit includes an earth-boring element and a percussion element. The earth-boring element and the percussion element are coaxially arranged, with the earth-boring element surrounding the percussion element. A reciprocating member of the percussion element may oscillate in a manner that enables a bottom end of the reciprocating member to repeatedly protrude from a bottom end of the earth-boring element and to be repeatedly withdrawn. A configuration of the earth-boring element may enable it to drill into and remove some materials from an earth formation, while the percussion element may enable the hybrid bit to drill into and remove difficult-to-drill materials, including abrasive materials and/or materials with high compressive forces, such as chert.

A hybrid bit includes an earth-boring element and a percussion element. The earth-boring element and the percussion element are coaxially arranged, with the earth-boring element surrounding the percussion element. A reciprocating member of the percussion element may oscillate in a manner that enables a bottom end of the reciprocating member to repeatedly protrude from a bottom end of the earth-boring element and to be repeatedly withdrawn. A configuration of the earth-boring element may enable it to drill into and remove some materials from an earth formation, while the percussion element may enable the hybrid bit to drill into and remove difficult-to-drill materials, including abrasive materials and/or materials with high compressive forces, such as chert.

A piloted rock drill bit includes an integral body having a pilot drill section, a reaming section and a mounting base section extending along a longitudinal axis. The reaming section includes four wings extending from the longitudinal axis in an X pattern. A cutting carbide member is secured to each wing. Waste debris ejection slots extend radially into the reaming section between the wings. The pilot drill section includes a post. A leading carbide member is secured to the post. The leading carbide member includes a pair of sloped surfaces extending forwardly towards each other and intersecting at a leading cutting edge which extends perpendicular to the longitudinal axis. The leading cutting edge and sloped surfaces extend along a crescent shaped arc. An air delivery bore extends through the body to discharge openings located between the leading cutting edge and wings which extend radially perpendicular to the leading cutting edge.

A piloted rock drill bit includes an integral body having a pilot drill section, a reaming section and a mounting base section extending along a longitudinal axis. The reaming section includes four wings extending from the longitudinal axis in an X pattern. A cutting carbide member is secured to each wing. Waste debris ejection slots extend radially into the reaming section between the wings. The pilot drill section includes a post. A leading carbide member is secured to the post. The leading carbide member includes a pair of sloped surfaces extending forwardly towards each other and intersecting at a leading cutting edge which extends perpendicular to the longitudinal axis. The leading cutting edge and sloped surfaces extend along a crescent shaped arc. An air delivery bore extends through the body to discharge openings located between the leading cutting edge and wings which extend radially perpendicular to the leading cutting edge.

A piloted rock drill bit includes an integral body having a pilot drill section, a reaming section and a mounting base section extending along a longitudinal axis. The reaming section includes four wings extending from the longitudinal axis in an X pattern. A cutting carbide member is secured to each wing. Waste debris ejection slots extend radially into the reaming section between the wings. The pilot drill section includes a post and a leading carbide member. The leading carbide member includes a pair of sloped surfaces extending forwardly towards each other and intersecting at a leading cutting edge. The leading cutting edge and sloped surfaces extend along a crescent shaped arc. Forward air delivery bores extend through the body to forward discharge openings at the pilot drill section. Rear air delivery bores extend through the body to rear discharge opening at the waste debris ejection slots.

A piloted rock drill bit includes an integral body having a pilot drill section, a reaming section and a mounting base section extending along a longitudinal axis. The reaming section includes four wings extending from the longitudinal axis in an X pattern. A cutting carbide member is secured to each wing. Waste debris ejection slots extend radially into the reaming section between the wings. The pilot drill section includes a post and a leading carbide member. The leading carbide member includes a pair of sloped surfaces extending forwardly towards each other and intersecting at a leading cutting edge. The leading cutting edge and sloped surfaces extend along a crescent shaped arc. Forward air delivery bores extend through the body to forward discharge openings at the pilot drill section. Rear air delivery bores extend through the body to rear discharge opening at the waste debris ejection slots.

An apparatus for boring a wellbore, including a bit body having a first end, an inner cavity, and a second end. The first end is connected to a workstring that is configured to deliver a rotational force to the bit body. The inner cavity contains a profile having a first radial cam surface. The second end includes a working face containing a cutting member. The apparatus also includes a pilot bit rotatively connected within the inner cavity. A second radial cam surface is contained on a first end of the pilot bit. The first and second radial cam surfaces are operatively configured to deliver a hammering force. A second end of the pilot bit may include an engaging surface configured to engage a formation surrounding the wellbore. The bit body rotates relative to the pilot bit.

An apparatus for boring a wellbore, including a bit body having a first end, an inner cavity, and a second end. The first end is connected to a workstring that is configured to deliver a rotational force to the bit body. The inner cavity contains a profile having a first radial cam surface. The second end includes a working face containing a cutting member. The apparatus also includes a pilot bit rotatively connected within the inner cavity. A second radial cam surface is contained on a first end of the pilot bit. The first and second radial cam surfaces are operatively configured to deliver a hammering force. A second end of the pilot bit may include an engaging surface configured to engage a formation surrounding the wellbore. The bit body rotates relative to the pilot bit.

A drill bit includes a bit body; a pad associated with the bit body; and a rate control device coupled to the pad that extends from a bit surface at a first rate and retracts from an extended position to a retracted position at a second rate in response to external force applied onto the pad. The rate control device includes a piston for applying a force on the pad; a biasing member that applies a force on the piston to extend the pad at the first rate; a fluid chamber associated with the piston; and a pressure management device for controlling a fluid pressure within the fluid chamber.