A tool string carrying an external tool, such as a liner hanger, on a release mechanism is lowered into the wellbore. Interlocking lugs and J-slot profile, defined between the exterior surface of the mandrel and interior surface of the release mechanism, allow relative movement of release mechanism and mandrel without releasing the release mechanism. The relative movement allows mechanical operation of a valve or other tool positioned below the release mechanism. Weight-down and rotation of the tool string and mandrel actuates the lower valve assembly by turning a sleeve into alignment with cooperating members of the mandrel. The sleeve, no longer constrained, moves longitudinally in response to a biasing mechanism. Movement of the sleeve allows closure of the valve. After actuation of the valve tool, further weight-down releases the release mechanism from the carried tool.

A recirculating gravel pack system includes a tubular member having an outer surface, an inner surface defining a flow path, a first opening extending from the inner surface through the outer surface and a second opening, spaced from the first opening extending from the inner surface through the outer surface. A screen is positioned about the tubular member spaced from the outer surface defining a passage that is selectively fluidically connected to the second opening. A return tube extends between the screen and the outer surface running axially along the tubular member. The return tube includes a first end defining an inlet arranged in the passage and a second end defining an outlet positioned in a low-pressure zone outside the passage downhole from the first opening.

A resilient seal includes an annular body portion and a seating surface defined by the annular body portion and configured to interface with a seat of a subsurface safety valve. The resilient seal further includes a plurality of sealing surfaces defined by the annular body portion. Each sealing surface of the plurality of sealing surfaces is positioned to interface with a flapper of the subsurface safety valve in a closed position of the flapper of the subsurface safety valve. Additionally, the resilient seal includes at least one annular channel defined by the annular body portion between adjacent sealing surfaces of the plurality of sealing surfaces.

A flapper and seat assembly, and systems and methods utilizing such assembly, are disclosed. The flapper and seat assembly includes a tubular metallic seat having a bore therethrough. The tubular metallic seat is one solid unit. The flapper and seat assembly further includes a hinge coupled to the tubular metallic seat and a flapper. The flapper is pivotally mounted to the hinge such that it is rotatable between an open position and a closed position. The flapper and seat assembly also includes a secondary sealing element located between the flapper and the tubular metallic seat. The secondary sealing element is one of an undulating or curved lip seal. The flapper and seat assembly further includes a seal that is formed between a sealing surface of the flapper and a sealing surface of the tubular metallic seat. The seal comprises an angle measured from a plane perpendicular to the centerline of the flapper and seat assembly.

A safety valve for a wellbore can include a piston, a flapper valve, a flow tube, a series of outer magnets, and a series of inner magnets. The piston can displace the flow tube, which can operate the flapper valve. The series outer magnets can be attached to an outer wall of the piston. The series of inner magnets can be attached to a flow tube of the safety valve. The series of outer magnets and the series of inner magnets can be arranged in a non-alternating polarity pattern. The non-alternating polarity pattern can be ordered in such a way that a first force to decouple the series of inner magnets from the series of outer magnets is larger than a second force to recouple the series of inner magnets to the series of outer magnets.

A polymetaphosphate composition and method for temporarily sealing a perforation in a wellbore to facilitate a treatment therein and a well tool which can include a flow path, and a flow blocking device which selectively prevents flow through the flow path. The well tool can include a polymetaphosphate composition. A method of constructing a downhole well tool can include forming a structure of a solid mass comprising a polymetaphosphate composition, and incorporating the structure into the well tool.

Apparatus, systems, and methods for reverse circulation cementing a tubular string in a wellbore. One such method includes reverse circulating cement slurry down an annulus defined between the tubular string and the wellbore. During the reverse circulation, a flow control device located in the tubular string is closed to prevent, or at least reduce, flow of the cement slurry from the annulus into the tubular string. The closure of the flow control device causes a pressure pulse in the wellbore. After the flow control device is closed, the reverse circulation is stopped. During a time interval between the closure of the flow control device and the stoppage of the reverse circulation, a shock absorber associated with the flow control device absorbs the pressure pulse in the wellbore so that a pressure in the wellbore is maintained within an acceptable range.

A flapper check valve employed to prevent flow up the work string while allowing flow down the work string and into the well is disclosed. The check valve is activated by a compression spring, which then acts on a ball which will further act on a cam profile attached to the back of a flapper. The apparatus causes the flapper to default to the closed position when the flow is stopped, regardless of the position of the valve, even when gravity is acting against the flapper. The compression spring also allows for an apparatus which possesses lower operating stresses on the spring.

A dual valve downhole tool for reverse cementing in a wellbore can include: a body configured to fit within a casing string; an inner sleeve located within the body; a first valve located within the body and configured to open and close a fluid flow path through the body, and wherein the first valve is configured to be in an open position during placement of the downhole tool in the wellbore; and a second valve located within the body and configured to open and close the fluid flow path through the body, wherein the second valve is configured to be in a closed position during placement of the downhole tool in the wellbore, and wherein shifting of the inner sleeve after placement of the downhole tool closes the first valve and opens the second valve. Reverse cementing can commence after the second sleeve has converted to the open position.

A system and method of reverse stage cementing in which flow into a casing string from an annulus between the casing string and wellbore walls is pressure dependent; the flow is blocked after stage completion. The flow enters the casing string through a cementing sub integrally formed in the casing string. A flapper valve is in a sidewall of the cementing sub that opens when pressure in the annulus reaches a threshold value, and remains open until the annulus pressure falls below the threshold value. Flapper valve actuation is controlled by a hinge spring that is calibrated to open and close the flapper valve based on the annulus pressure. Also in the cementing sub is a sleeve that is positioned behind the flapper valve after the reverse stage cementing is completed. Sleeve actuation is timed to allow adequate time for the flapper valve to return to the closed position.