A drilling assembly includes a drill string configured to be disposed within a wellbore. The drilling assembly also includes a sub fluidically coupled to the drill string. The sub includes a mandrel fixed to the drill string and defines an external helically undulated surface and a bore configured to flow drilling fluid received from the drill string. The sub includes a sleeve rotationally coupled to and disposed outside the mandrel. The sleeve has an internal helically undulated surface corresponding with the external helically undulated surface of the mandrel to form, with the mandrel, a progressive cavity. The progressive cavity receives fluid from the bore of the mandrel to rotate the sleeve as the drilling fluid flows along the cavity. The sub also includes a valve configured to regulate a flow of the drilling fluid along the bore to direct fluid toward or away from the progressive cavity.

A drilling assembly includes a drill string configured to be disposed within a wellbore. The drilling assembly also includes a sub fluidically coupled to the drill string. The sub includes a mandrel fixed to the drill string and defines an external helically undulated surface and a bore configured to flow drilling fluid received from the drill string. The sub includes a sleeve rotationally coupled to and disposed outside the mandrel. The sleeve has an internal helically undulated surface corresponding with the external helically undulated surface of the mandrel to form, with the mandrel, a progressive cavity. The progressive cavity receives fluid from the bore of the mandrel to rotate the sleeve as the drilling fluid flows along the cavity. The sub also includes a valve configured to regulate a flow of the drilling fluid along the bore to direct fluid toward or away from the progressive cavity.

A lateral wellbore is formed from a high side of a horizontal portion of a primary wellbore with a drill bit assembly that has a selectively extendable pilot bit. The drill bit assembly is mounted on a lower end of a drill string. A bit guide is disposed adjacent the drill bit assembly for urging the drill bit assembly in a lateral direction against the high side of the primary wellbore. Rotating the drill bit assembly while urging the drill bit assembly upward creates a groove in a subterranean formation adjacent the primary wellbore. This forms a ledge at a far end of the groove. The drill string is then drawn back from the groove, and the pilot bit is deployed. Urging the drill bit assembly forward engages the pilot bit with the ledge, providing leverage for retaining the drill bit assembly in an orientation for excavating the lateral wellbore.

A lateral wellbore is formed from a high side of a horizontal portion of a primary wellbore with a drill bit assembly that has a selectively extendable pilot bit. The drill bit assembly is mounted on a lower end of a drill string. A bit guide is disposed adjacent the drill bit assembly for urging the drill bit assembly in a lateral direction against the high side of the primary wellbore. Rotating the drill bit assembly while urging the drill bit assembly upward creates a groove in a subterranean formation adjacent the primary wellbore. This forms a ledge at a far end of the groove. The drill string is then drawn back from the groove, and the pilot bit is deployed. Urging the drill bit assembly forward engages the pilot bit with the ledge, providing leverage for retaining the drill bit assembly in an orientation for excavating the lateral wellbore.

A reamer for use in horizontal directional drilling back-reaming operations. The reamer comprises an elongate body having an intermediate section, a first end, and a second end. The circumference of the intermediate section is larger than the circumference of the first end and the second end. A pocket or a plurality of pockets are formed on the intermediate section. The pockets are configured such that a cutter or a plurality of cutters may be secured within the pockets via the use of fasteners. The cutters are replaceable with cutters of like size or cutters of different sizes and shapes.

A reamer for use in horizontal directional drilling back-reaming operations. The reamer comprises an elongate body having an intermediate section, a first end, and a second end. The circumference of the intermediate section is larger than the circumference of the first end and the second end. A pocket or a plurality of pockets are formed on the intermediate section. The pockets are configured such that a cutter or a plurality of cutters may be secured within the pockets via the use of fasteners. The cutters are replaceable with cutters of like size or cutters of different sizes and shapes.

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 modular reamer for use in a wellbore comprises an uphole end member, a center member, and a downhole member, with reamer sleeves that removably slides over a sleeve mounting portion of the center member or one of the end members, and are held between the end members and the center members when assembled into a downhole tool. The reamer sleeves may be positioned at any desired rotational angle relative to each other and are prevented from rotational movement relative to the center member by spines or keys formed on the mating surfaces of the reamer sleeves and corresponding members of the modular eccentric reamer.

A modular reamer for use in a wellbore comprises an uphole end member, a center member, and a downhole member, with reamer sleeves that removably slides over a sleeve mounting portion of the center member or one of the end members, and are held between the end members and the center members when assembled into a downhole tool. The reamer sleeves may be positioned at any desired rotational angle relative to each other and are prevented from rotational movement relative to the center member by spines or keys formed on the mating surfaces of the reamer sleeves and corresponding members of the modular eccentric reamer.