A flapper valve assembly that includes a tubular forming an interior passageway and comprising an internal shoulder; a valve seat forming a portion of the interior passageway and spaced from the internal shoulder to form a flapper chamber; a flapper plate that is pivotably mounted to the tubular at a pivot point and positioned within the flapper chamber; wherein the flapper plate is pivotable within the flapper chamber between a valve closed and valve open position; and a first spring extending within the flapper chamber and engaging the flapper plate such that the flapper plate is biased towards the valve closed position; wherein the first spring comprises spaced right and left arms that are in contact with the flapper plate; and wherein, when the flapper plate is in the valve closed position, each of the right and left arms extends away from the flapper plate and towards the internal shoulder.

A sliding sleeve well device has a first sliding sleeve received in a second sliding sleeve. A polymer seal having a polymer sealing surface is between and in sealing contact with the sliding sleeves. A metal-to-metal seal is between the sliding sleeves and actuable into sealing contact with the first and second sliding sleeves.

A sliding sleeve well device has a first sliding sleeve received in a second sliding sleeve. A polymer seal having a polymer sealing surface is between and in sealing contact with the sliding sleeves. A metal-to-metal seal is between the sliding sleeves and actuable into sealing contact with the first and second sliding sleeves.

A subsurface safety valve assembly that includes a valve housing comprising a valve seat with a circumference and a seat seal surface. The valve assembly also includes a flapper rotatably connected to the valve housing and comprising a flapper seal surface. The flapper is rotatable into sealing engagement with the seat seal surface in a closed position to form a circumferential surface-to-surface seal. The valve assembly also includes a dovetail groove cut into the seat seal surface or the flapper seal surface and a seal ring held within the dovetail groove and positioned to form a seal against the seal ring when the flapper is in the closed position. The seat seal surface, the flapper seal surface, the dovetail groove, and the seal ring are shaped such that the load on the seal ring is uniform around the seal ring when the flapper is in the closed position.

A subsurface safety valve assembly that includes a valve housing comprising a valve seat with a circumference and a seat seal surface. The valve assembly also includes a flapper rotatably connected to the valve housing and comprising a flapper seal surface. The flapper is rotatable into sealing engagement with the seat seal surface in a closed position to form a circumferential surface-to-surface seal. The valve assembly also includes a dovetail groove cut into the seat seal surface or the flapper seal surface and a seal ring held within the dovetail groove and positioned to form a seal against the seal ring when the flapper is in the closed position. The seat seal surface, the flapper seal surface, the dovetail groove, and the seal ring are shaped such that the load on the seal ring is uniform around the seal ring when the flapper is in the closed position.

A downhole valve to be used in a flow management system that comprises a valve inlet for coupling with a hydrocarbon reservoir pump outlet, a valve outlet for coupling with production tubing transport to the surface pumped hydrocarbons, a valve body with a valve body centerline that extends between the valve inlet and outlet, and a spill port for bypassing a backflow.

A fracturing method, to cause a crack in bedrock, includes installing a depressurizing device in a well in the bedrock, and depressurizing the inside of the well with the installed depressurizing device. The installing step includes installing, in the well, a connecting pipe, which is connected to the depressurizing device, and a packer, which is attached to the connecting pipe, and the depressurizing step includes shutting off a gap between the well and the connecting pipe, with the packer, and depressurizing a region in the well below the packer, with the depressurizing device.

A flow control device including a housing having a flow port therein, the flow port including a first end and a second end, a first gate having a specific gravity greater than water disposed in the housing adjacent a first end of the port and movable between a position of nonobstruction of the first end of the port and a position of obstruction of the first end of the port; and a second gate disposed in the housing, the second gate having a specific gravity about the same as a specific gravity of formation water in a formation in which the device is intended to be employed, the second gate disposed to control flow at the second end of the port.

A flow control device including a housing having a flow port therein, the flow port including a first end and a second end, a first gate having a specific gravity greater than water disposed in the housing adjacent a first end of the port and movable between a position of nonobstruction of the first end of the port and a position of obstruction of the first end of the port; and a second gate disposed in the housing, the second gate having a specific gravity about the same as a specific gravity of formation water in a formation in which the device is intended to be employed, the second gate disposed to control flow at the second end of the port.

A valve housing has a first flapper moveable from an open position in the housing in which two-way flow is allowed to a closed position in which only one-way flow is permitted. A first collet sleeve is moveable from a first position to a second position in the valve housing. The first collet sleeve in the first position retains the flapper valve in the open position. The collet sleeve is moveable from a first position to a second position which allows the flapper to move to a closed position.