Abstract: 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.

Abstract: A drill bit for drilling a bore, the drill bit comprising: an outer housing; a primary cutting structure defining a cutting plane of a first diameter; a flow path arranged to let drilling fluid flow through the drill bit; and a deployable blade assembly at least partially located within the outer housing, the deployable blade assembly comprising a cutting structure and being arranged to be axially movable from a first position, in which the deployable cutting structure is recessed with respect to the primary cutting structure, towards the cutting plane, to a second position; wherein when the deployable blade assembly is in the second position, the deployable cutting structure defines a cutting diameter which is less than or equal to the first diameter.

Abstract: A selective downhole actuator comprising at least a first actuator position, a second actuator position and a third actuator position. The selective downhole actuator is reconfigurable between the first actuator position and the second actuator position. The selective actuator is selectively reconfigurable to the third actuator position by varying an operating parameter during a transition of the selective downhole actuator between the first and second actuator positions.

Abstract: A rotary downhole tool, for example in the form of a drill bit, is described that includes a tool body, the body defining a gauge region, and at least one gauge roller rotatably mounted to the body.

Abstract: A vibration assembly of a drilling tool for drilling a wellbore penetrating a subterranean formation is disclosed. The downhole drilling tool includes a drill string, a bottomhole assembly and a drill bit. The vibration assembly includes a housing (334a) operatively connectable to the bottomhole assembly, expanders (122) positionable in the housing and radially extendable and retractable thereabout, and a radial vibrator (comprising mandrel (446), enlarger spring (48), cam portion (458) and vibration spring (570) operatively connectable to the expanders to vibrationally move the expanders against the wall of the wellbore whereby movement of the downhole tool is altered during drilling.

Abstract: A processing apparatus includes a microwave processing chamber. In addition, the processing apparatus includes a rigid, rotatable feed wheel rotatable about an axis of rotation such that a part of the feed wheel is located within the processing chamber. Further, the processing apparatus includes a feed device configured to deposit materials to be processed onto the feed wheel. Still further, the processing apparatus includes an output into which processed materials from the feed wheel can be deposited.

Abstract: A drill bit (10), for example of a fixed cutter type, comprises at least one structure, for example a blade, having first and second rows of cutters (35a-h) thereon. The first row is configured to achieve suitable performance when the drill bit drills in concentric mode. The second row of cutters is configured to improve the performance of the first row of cutters when the drill bit drills in eccentric mode. For example, the second row increases depth of cut and wear resistance in eccentric mode drilling. The drill bit may be mounted on a bent motor (120) used in directional drilling.

Abstract: A downhole under-reamer for use in reaming a downhole bore. The under-reamer comprises a body and a plurality of cutters mounted on the body. The cutters are mounted on the body so as to be extendable from a retracted position to at least two extended positions. The at least two extended positions comprise reaming positions at respective first and second reaming diameters.

Abstract: An under-reaming tool comprises a body and a plurality of extendable cutters mounted on the body. The under-reaming tool is configured to be cycled between a first configuration in which the cutters are retracted and a second configuration in which the cutters are movable between retracted and extended positions. The under-reaming tool is configured to prevent extension of the cutters by an external fluid in the first and/or second configuration/s.

Abstract: A downhole motor (107) which comprises a stator housing (108), a rotor assembly (106) rotatable relative to said stator housing, and an arrangement for enabling, in use, a drill bit connected to the rotor assembly of said downhole motor to be rotated by rotating a drill string connected to said stator housing, wherein said arrangement comprises a unidirectional clutch (117) disposed between said rotor assembly and said stator housing and having at least one pawl which can be displaced between an inoperative position adjacent said stator housing and an operative position in which rotation of said stator housing by said drill string in one sense is transmitted to said rotor assembly via said at least one pawl, means biasing said at least one pawl towards said operative position, means retaining said at least one pawl in its inoperative position, and means which, when sufficient pulling force is applied to said drill string, will cause said means retaining said at least one pawl to release said at least one pawl

Abstract: A rotary downhole tool, for example in the form of a drill bit, is described that includes a tool body, the body defining a gauge region, and at least one gauge roller rotatably mounted to the body.

Abstract: A selective downhole actuator comprising at least a first actuator position, a second actuator position and a third actuator position. The selective downhole actuator is reconfigurable between the first actuator position and the second actuator position. The selective actuator is selectively reconfigurable to the third actuator position by varying an operating parameter during a transition of the selective downhole actuator between the first and second actuator positions.

Abstract: An under-reamer comprises a body and extendable cutters mounted on the body. The under-reamer is configured to be cycled between a first configuration in which the cutters are retracted and a second configuration in which the cutters are movable between retracted and extended positions. A control mechanism is provided and is configurable to prevent the under-reamer cycling between the first and second configurations and thus maintain the under-reamer in a selected one of the first and second configurations.

Abstract: A method of fabricating a structure having an open cell foam element includes providing an open cell foam element of metallic, diamond, ceramic and/or refractory material form, and/or having one or more metallic, diamond, ceramic and/or refractory material coatings, the foam element defining a plurality of interconnected cells. The method further includes locating a material within the cells, and treating the material, in situ, by sintering and/or infiltration, to form a continuous mesh or lattice structure that extends within and through the cells of the open cell foam element. Structures fabricated using the method are also described.

Abstract: A cutting element comprises a table of superhard material bonded to a substrate, wherein the table defines a cutting edge and has a chamfered peripheral edge, and a groove in a sidewall of the cutting element passes through the chamfered peripheral edge, so as to reduce the depth of the chamfer at the location of the groove.

Abstract: A cutting element comprises a primary cutter including a first table of a hard material bonded to a first substrate of less hard form, the first substrate of the primary cutter having a recess formed therein in which a secondary cutter is located, the secondary cutter comprising a second table of a hard material bonded to a second substrate of less hard material, the first and second tables being spaced apart from one another by at least part of the first substrate.

Abstract: A downhole actuating apparatus for actuating downhole. The apparatus is actuatable at the downhole location at, upon or during one or more particular cycle/s selectable from a sequence of cycles according to a predetermined selection. The downhole actuation comprises the release of at least one flowable object from the downhole location. The apparatus releases the at least one flowable object from the downhole location at, upon or during the particular cycle selectable from the sequence of cycles.

Abstract: A downhole under-reamer for use in reaming a downhole bore. The under-reamer comprises a body and a plurality of cutters mounted on the body. The cutters are mounted on the body so as to be extendable from a retracted position to at least two extended positions. The at least two extended positions comprise reaming positions at respective first and second reaming diameters.

Abstract: A downhole tool (10) comprising rotatable inner and outer sleeves (62, 63). The sleeves (62, 63) comprise coupling portions for transmitting a torque between the sleeves (62, 63). The tool is reconfigurable between a first configuration whereby the coupling portions are axially misaligned to prevent transmission of torque between the inner and outer sleeves (62, 63), and a second configuration whereby the coupling portions are axially aligned to permit a transmission of torque between the sleeves (62, 63). At least one of the coupling portions is configured to prevent the transmission of torque above a predetermined torque threshold.

Abstract: A drill bit comprises at least one blade, comprising a plurality of cutting elements in the form of polycrystalline diamond cutters disposed on a leading edge of the blade, at least one diamond impregnated cutting region, disposed behind the leading edge of the blade, and wherein at least one of the cutters disposed on the leading, edge is an off-tip cutting element, arranged so that it does not engage with the formation during drilling until bit wear has taken place.