Bottom hole assemblies with a combined roller-underreamer assembly can include: a body configured to be attached to a drill pipe; an uphole ring attached to the body; a downhole ring attached to the body between the uphole ring and the downhole end of the body; a sliding ring mounted around the body between the uphole ring and the downhole ring; a set tube slidably mounted around the body between the uphole ring and the sliding ring; a reamer assembly with at least one first articulated arm with extending between the uphole ring and the downhole end of the set tube; and a roller assembly with: at least one second articulated arm extending between the uphole end of the set tube and the sliding ring; and a rolling positioned at a joint of each second articulated arm.

A wellbore reamer assembly positionable on a drill string in a wellbore includes a reamer body having an internal cavity and multiple radial openings, multiple cutting structures each positioned in one of the radial openings in the reamer body, and a fluid-activated expandable support element positioned in the internal cavity of the reamer body adjacent the cutting structures. The cutting structures are extendable radially away from a central longitudinal axis of the reamer body through respective radial openings and retractable toward the central longitudinal axis of the reamer body.

This cutting assembly provides a radially grooved body insert upon which cutter arms with complementary radial grooves may translate to extend the cutter arms in a radial fashion from a body of a downhole drilling assembly. This improved cutting assembly design can be incorporated into an underreamer, hole opener, drill bit, or section mill.

Using a rock crushing system for widening a pilot hole on rocky terrain includes taking a plurality of crushing elements, for example roller bits and/or cutter discs, pressing the crushing elements against the lateral wall of the pilot hole and at the same time rolling the crushing elements along a cylindrical portion of the lateral wall, widening the pilot hole. The crushing elements, free to rotate with respect to an axis thereof, are radially pushed by hydraulic cylinders. Stabilising means exemplarily include a basket abutting the lateral wall to keep a main body bearing the hydraulic cylinders centered with respect to an axis of the pilot hole during the rock crushing.

The present disclosure relates to an underreamer. In one aspect, the underreamer comprises a body, the body comprising at least one pocket therein, the underreamer further comprising at least one cutter secured with respect to the body, at least one actuating mechanism for moving the cutter between a retracted position in the pocket, and an extended position in which only the cutter projects from the body. In one aspect, the or each actuating mechanism comprises a piston for driving extension of the cutter, and a linkage to a cutter arm with respect to which the cutter is mounted, and a return spring for biasing the cutter to the retracted position.

A downhole tool includes a housing; a first piston arranged within the housing such that it can move axially under the action of fluid flowing through the tool; and an indexer configured to control axial movement of the first piston between a first, second and third axial position. The indexer is configured such that the first piston can be selectively moved into the third position in accordance with a variation of a flow of fluid through the tool. A second piston is movable between a closed position in which fluid flowing through the tool is restricted from communicating with an activation chamber and an open position in which fluid flowing through the tool is permitted to communicate with the activation chamber; wherein the second piston is configured to move between the closed position and the open position in response to the first piston moving to the third axial position.

Bottom hole assemblies with a combined roller-underreamer assembly can include: a body configured to be attached to a drill pipe; an uphole ring attached to the body; a downhole ring attached to the body between the uphole ring and the downhole end of the body; a sliding ring mounted around the body between the uphole ring and the downhole ring; a set tube slidably mounted around the body between the uphole ring and the sliding ring; a reamer assembly with at least one first articulated arm with extending between the uphole ring and the downhole end of the set tube; and a roller assembly with: at least one second articulated arm extending between the uphole end of the set tube and the sliding ring; and a rolling positioned at a joint of each second articulated arm.

A compression-set straddle packer with fluid pressure-boosted packer set has a two-part multicomponent mandrel and a multicomponent sliding sleeve that reciprocates within a limited range on an upper part of the two-part multicomponent mandrel. A two-part lower packer element compression sleeve in a lower part of the two-part multicomponent mandrel reciprocates on a packer element piston mandrel component and pressure-boosts compression of a lower packer element when high-pressure fluid is pumped into the straddle packer. A bias element constantly resists relative movement between the multicomponent mandrel and the multicomponent sliding sleeve and balances pressure-boost between the lower packer element and an upper packer element supported by the upper part of the two-part multicomponent mandrel.

A compression-set straddle packer with fluid pressure-boosted packer set has a two-part multicomponent mandrel and a multicomponent sliding sleeve that reciprocates within a limited range on an upper part of the two-part multicomponent mandrel. A two-part lower packer element compression sleeve in a lower part of the two-part multicomponent mandrel reciprocates on a packer element piston mandrel component and pressure-boosts compression of a lower packer element when high-pressure fluid is pumped into the straddle packer. A bias element constantly resists relative movement between the multicomponent mandrel and the multicomponent sliding sleeve and balances pressure-boost between the lower packer element and an upper packer element supported by the upper part of the two-part multicomponent mandrel.

The present disclosure relates to an underreamer. In one aspect, the underreamer comprises a body, the body comprising at least one pocket therein, the underreamer further comprising at least one cutter secured with respect to the body, at least one actuating mechanism for moving the cutter between a retracted position in the pocket, and an extended position in which only the cutter projects from the body. In one aspect, the or each actuating mechanism comprises a piston for driving extension of the cutter, and a linkage to a cutter arm with respect to which the cutter is mounted, and a return spring for biasing the cutter to the retracted position.