Equipment and methods for use in conjunction with an underbalanced well completion. A valve 12 for use in a subterranean well 16 in conjunction with a tool 22 conveyed through the valve 12 in a container 26 is provided. The valve 12 includes a passage 18 formed longitudinally through the valve 12, a closure assembly 28 which selectively permits and prevents flow through the passage 18, and an engagement device which engages the container 26 as the tool 22 is conveyed through the passage 18. The closure assembly 28 permits flow through the passage 18 when the container 26 is conveyed into the passage 18, and the closure assembly 28 prevents flow through the passage 18 when the container 26 is removed from the passage 18. Engagement between the container 26 and the engagement device separates the tool 22 from the container 26.

A drillable regulating valve for use in wells to regulate back-flow of fluid, has a valve closure element (28) movable into and out of engagement with a seat (24a), and a biasing element (30) for urging the valve element into engagement with the seal area to close the valve. The closure element is preferably a poppet valve mounted on a check valve member (24).

A method of servicing a well and an associated well system provide convenient downhole hydraulic path selection. A hydraulic path selector is preconfigured for selection of a desired hydraulic path set, and then the selector is conveyed into a tubular string (50) in which a hydraulic manifold (68) is connected to one or more hydraulically operable tools (10). When engaged with the manifold (68), the selector selects an appropriate hydraulic path set (64,66), which selection determines which tool (10) is to be operated and/or in what manner the tool (10) is to be operated.

A floating apparatus for a well casing includes a check valve (30A) disposed in a sleeve (32A), wherein the sleeve (32A) is receivable within an outer case (80). The check valve (30A) includes a valve housing (44A), wherein a first cement body portion (78A) attaches the valve housing (44A) to the sleeve (32A). A second cement body portion (96) is provided for attachment of the sleeve to the outer case, thereby to hold the sleeve (32A) and affixed valve (30A) within the outer case which is threadably connectable with the well casing. Preferably, the second cement body portion only partially fills an annulus between the sleeve and outer case, wherein the well casing is received in the annulus when threadably connected to the outer case.

A packer setting tool (130) for setting a packer of the type which is set by displacing a mandrel relative to an outer slip assembly thereof. The tool (130) comprises a generally tubular mandrel assembly (146) having a flow passage (134) formed therethrough and a first port (144) formed through a sidewall thereof, the mandrel assembly (146) being attachable to the packer mandrel; a piston (162) reciprocably disposed relative to the mandrel assembly (146) and displaceable relative to the mandrel assembly (146) in response to fluid pressure in the first port (144); and an isolation structure (132) positionable in a selected one of first and second positions relative to the mandrel assembly (146). The isolation structure (132) blocks fluid communication between the flow passage (134) and the first port (144) in the first position, and the isolation structure uncovers the first port (144) and permitting fluid flow between the first port (144) and the flow passage (134) in the second position.

A plug provided with a holding device for releasably attaching said plug to a support having a shoulder, characterised in that said holding device comprises a tubular sleeve to which said plug is secured, said tubular sleeve having an external ring which, in use, rests on said shoulder and supports said plug, the arrangement being such that when said sleeve is subject to sufficient force said external ring will shear and thus release said plug from said support.

A method of servicing a well and an associated well system provide convenient downhole hydraulic path selection. A hydraulic path selector is preconfigured for selection of a desired hydraulic path set, and then the selector is conveyed into a tubular string (50) in which a hydraulic manifold (68) is connected to one or more hydraulically operable tools (10). When engaged with the manifold (68), the selector selects an appropriate hydraulic path set (64,66), which selection determines which tool (10) is to be operated and/or in what manner the tool (10) is to be operated.

A downhole tool (34) comprising a housing (60), a mandrel (76) slidably disposed within the housing (60), the mandrel (76) having a fluid passageway (52) extending axially therethrough, a valve disposed within the mandrel (76), the valve having first and second positions to selectively permit and prevent fluid flow through the fluid passageway (52) of the mandrel (76) and first (98) and second pistons slidably disposed between the housing (60) and the mandrel (76). The first (98) and second pistons are slidably displaceable in opposite directions relative to the housing (60) in response to a differential fluid pressure. The first (98) and second pistons are selectively engagable with the mandrel (76) to respectively displace the mandrel (76) in first and second directions, thereby operating the valve between said first and second positions.