A method of running casing in a dual gradient system includes lowering a casing into a low density fluid region and allowing the low density fluid to enter the casing; releasing a plug into the casing; supplying a high density fluid behind the plug; and lowering the casing into a high density fluid region until target depth is reached.

An outer casing string, including a surface casing head, and associated installation method. In some embodiments, the surface casing head includes an outer tubular member insertable through a diverter of an installed conductor system, an inner tubular member at least partially disposed within and moveable relative to the outer tubular member, and a sleeve ring rotatably coupled to the inner tubular. The outer tubular member has an annular recess. The sleeve ring includes a snap ring that is displaceable between an extended position and a retracted position. In the extended position, at least a portion of the snap ring is received within the annular recess, and the outer tubular member is axially immovable relative to the inner tubular member. In the retracted position, no portion of the snap ring is received within the annular recess, and the outer tubular member is axially moveable relative to the inner tubular member.

The present invention relates to offshore oil and gas exploration drilling field and, in particular, to a surface layer conductor running tool for deep-water well drilling, which is used to run a conductor to a designated position, so that the drill stem can be released and the drilling can be continued. The surface layer conductor running tool for deep-water well drilling comprises a mandrel, an inner sleeve, an outer sleeve, and a main body, wherein the inner sleeve, the outer sleeve, and the main body are fitted over the mandrel sequentially; the inner sleeve can slide up and down but cannot rotate in relation to the mandrel, the outer sleeve and the inner sleeve are connected via a transmission thread pair, and the main body is situated on the inner sleeve; a retaining pawl penetrating the main body and radially slidable in horizontal direction; and an anti-rotation pin penetrating the main body and the outer sleeve, so that the outer sleeve can move up and down in the main body only, but cannot rotate.

The present invention relates to offshore oil and gas exploration drilling field and, in particular, to a surface layer conductor running tool for deep-water well drilling, which is used to run a conductor to a designated position, so that the drill stem can be released and the drilling can be continued. The surface layer conductor running tool for deep-water well drilling comprises a mandrel, an inner sleeve, an outer sleeve, and a main body, wherein the inner sleeve, the outer sleeve, and the main body are fitted over the mandrel sequentially; the inner sleeve can slide up and down but cannot rotate in relation to the mandrel, the outer sleeve and the inner sleeve are connected via a transmission thread pair, and the main body is situated on the inner sleeve; a retaining pawl penetrating the main body and radially slidable in horizontal direction; and an anti-rotation pin penetrating the main body and the outer sleeve, so that the outer sleeve can move up and down in the main body only, but cannot rotate.

Apparatus for drilling and lining a wellbore is described herein. A method of drilling and lining a wellbore is also described herein. A liner hanger is provided, secured in use on a liner. The liner hanger is operable selectively to be set and unset. The liner hanger is adapted to support the liner within an existing casing when set and to release the liner from the casing when unset. A liner hanger setting tool is provided, secured in use on a drill string. The liner hanger setting tool is actuatable selectively to set and unset the liner hanger. The liner hanger setting tool is operable selectively to be activated and deactivated. The liner hanger setting tool is adapted to attach to the liner and/or liner hanger when activated, to support the liner, and to release from the liner and/or liner hanger when deactivated. The method comprises the following steps: (a) setting the liner hanger by actuating the liner hanger setting tool; (b) deactivating the liner hanger setting tool; (c) extending the borehole using the drill string; (d) returning the drill string to its position at the setting step or the deactivating step; (e) activating the liner hanger setting tool; (f) unsetting the liner hanger by actuating the liner hanger setting tool; and (g) lowering the liner down the extended borehole on the drill string.

System, method, and apparatus for harnessing geothermal power from superhot geothermal fluid (SHGF) and magma reservoirs. An exemplary embodiment is directed to a cased wellbore for use in generating superheated steam. The cased wellbore includes a first end at a surface, a second end at an underground reservoir of magma, and a fluid pathway extending from an inlet at the first end to the second end and then from the second end to an outlet at the first end. The fluid pathway is configured to receive saturated steam at the inlet and expel superheated steam from the outlet, and the saturated steam is transformed into superheated steam in the fluid pathway at the second end of the cased wellbore.

A well construction method in which a drilled bore is lined with a plurality of successively smaller diameter sections of bore-lining tubing including casing sections a liner section is provided. A liner is provided with an inner string extending to a distal end of the liner. The liner and the inner string are run into a distal section of a drilled bore. Settable material is pumped from surface through the inner string and through the distal end of the liner to partially fill an outer annulus surrounding the liner. Fluid displaced from the outer annulus and a portion of the settable material is permitted to flow from the outer annulus through a port in the liner and into an inner annulus between the inner string and the liner.