A packoff device is disclosed for sealing an annulus within a wellbore, and for bypassing the sealed annulus. The packoff device may include a mandrel having a bore formed axially therethrough and first and second ports extending radially from the bore. A sealing element that extends radially-outwardly from the mandrel may be positioned axially between the first and second ports, and may create a seal within an annulus between the mandrel and a casing, to isolate a portion of the annulus above the sealing element from a portion below the sealing element. A sleeve within the bore may, with the mandrel, form a channel providing fluid communication between the first and second ports. The sleeve may be movable between open and closed states. The first and second ports may be unobstructed by the sleeve in the open state, one or more may be obstructed in the closed state.

A zone isolation cementing system includes a tubular having a longitudinal axis and a first flow-controlled port, a first conduit having a first end and a second end, the first end fluidically connected to the first flow-controlled port, a first distributor manifold arranged to deliver cement slurry exteriorly of the tubular, the second end of the first conduit fluidically connected to the first distributor manifold, and a first settable packer disposed exteriorly of the tubular and arranged longitudinally between the first flow-controlled port and the first distributor manifold.

A stage tool for wellbore annular cementing may be opened for cementing by hydraulic actuation of a sliding sleeve valve from over a fluid port. After sufficient cement has been introduced, the stage tool fluid port can be closed by compressing two telescopically arranged parts of its tubular body to further overlap each other and overlie the fluid port. This permits the stage tool to be closed without employing a plug.

A method and apparatus for efficiently extracting geothermal energy from a subterranean thermal reservoir through a wellbore where the heat exchange fluid is introduced at a slower velocity than the velocity at which the fluid is extracted. The method and apparatus further comprises a region void of cement between the outer wall of a casing and the inner wall of the wellbore, such that thermally conductive material can be injected therein.

A well tool for use in completing a wellbore includes a tubular housing having a central bore and a housing port through a wall of the tubular housing, an inner mandrel disposed within the tubular housing and selectively movable between a first, closed position and a second, open position in response to a fluid pressure in the central bore, a sealing element circumscribing a portion of the tubular housing, and a setting sleeve. The inner mandrel is configured to open the housing port when the inner mandrel is in the second, open position. The setting sleeve is movable between a first, retracted position and a second, expanded position, where the setting sleeve is configured to activate the sealing element in the second, expanded position in response to movement of the inner mandrel to the second, open position.

A rupture disc assembly and a float tool incorporating the rupture disc assembly is disclosed. The rupture disc assembly may include a rupture disc assembly comprising a rupture disc, an upper tubular portion and a lower tubular portion, and a securing mechanism for holding the rupture disc between the upper and lower tubular portions. A float tool for creating a buoyant chamber in a casing string may include the rupture disc assembly and a sealing device for sealing the lower end of the casing string, the buoyant, sealed chamber may be created there between. In operation, applied fluid pressure causes the rupture disc to move downward. The rupture disc may be shattered by contact with a surface on the lower tubular portion. Full casing internal diameter may be restored in the region where the rupture disc formerly sealed the casing.

A downhole shifting sleeve device includes a first segment and a second segment each including a housing, a sleeve, and a seat surface connected to the sleeve. Each seat surface is configured to engage a plug traveling through an inner bore of the device, which transfers the associated sleeve from a first position to a second position. The seat surface of the second segment is formed by a selective seat assembly. When the first sleeve is in the first position, the selective seat assembly is in a retracted position in which an inner diameter of the selective seat assembly is greater than or equal to an inner diameter of the second sleeve. When the first sleeve is in the second position, the selective seat assembly is in a deployed position in which the inner diameter of the selective seat assembly is less than the inner diameter of the second sleeve.

A stage tool for wellbore annular cementing may be opened for cementing by hydraulic actuation of a sliding sleeve valve from over a fluid port. After sufficient cement has been introduced, the stage tool fluid port can be closed by compressing two telescopically arranged parts of its tubular body to further overlap each other and overlie the fluid port. This permits the stage tool to be closed without employing a plug.

A zone isolation cementing system includes a tubular having a longitudinal axis and a first flow-controlled port, a first conduit having a first end and a second end, the first end fluidically connected to the first flow-controlled port, a first distributor manifold arranged to deliver cement slurry exteriorly of the tubular, the second end of the first conduit fluidically connected to the first distributor manifold, and a first settable packer disposed exteriorly of the tubular and arranged longitudinally between the first flow-controlled port and the first distributor manifold.

The present invention provides wellbore pressure control system and method for well cementation stages, and relates to the offshore oil and gas exploitation field. The wellbore pressure control system comprises: an injection pump; and a control device, configured to control the injection pump to inject a fluid or gas through an injection pipeline to a return pipeline that communicates with an annular space of the wellbore to decrease the pressure in the return pipeline and thereby decrease the pressure in the annular space, wherein, the density of the fluid or gas is lower than the density of a drilling fluid in the annular space. The technical scheme of the present invention can effectively prevent leaky zones from being fractured by high-density cement slurry in the well cementation process that may cause safety accidents such as well kick and well blowout, etc.