Subsea test tree fast ball actuation with low pressure pump through capability

A method of operating a valve assembly within a wellbore, comprising:

• activating a fail-safe actuator comprising a main piston and an activation chamber containing a gas charge, wherein the main piston is sealingly coupled to the activation chamber and transmits a biasing force generated by the gas charge;
• rotationally translating a valve to contact a workstring having a fluid passage by axially translating a ball support by the fail-safe actuator, wherein the valve rotates from an open position in response to the axial translating of the ball support;
• shearing the workstring by the valve in response to the biasing force, wherein the valve rotationally translates into a shear position to shear the workstring into two portions, and wherein the main piston contacts the ball support and a limit shoulder when the valve is in the shear position;
• and
• rotationally translating the valve from the shear position to a closed position by axially translating the ball support by one or more push rods sealingly engaged with the main piston, wherein the one or more push rods are biased by the gas charge, and wherein a first wellbore environment above the valve is isolated from a second wellbore environment below the valve when the valve is in the closed position.

A method of operating a valve assembly within a wellbore, comprising:

• opening a valve assembly by transferring a first volume of fluid into a first chamber via a first fluid conduit;
• compressing a valve actuator with a second volume of fluid in a second chamber, wherein the valve actuator comprises a main piston sealingly coupled to an activation chamber containing a gas charge;
• transferring the first volume of fluid and the second volume of fluid from the first chamber and the second chamber;
• closing the valve assembly from an open position to a shear position via the main piston by transferring a third volume of fluid into a third chamber via a third fluid conduit as the first volume of fluid transfers out of the first chamber;
• and
• closing the valve assembly from the shear position to a closed position by one or more push rods, wherein the one or more push rods are sealingly coupled to the main piston, and
• wherein a biasing force exerted by the gas charge on the one or more push rods is less than a biasing force exerted by the gas charge on the main piston.

A valve assembly for controlling fluid communication along a wellbore tubular, the valve assembly comprising:

• a ball having a fluid passage and rotationally coupled to a ball support, wherein the ball is configured to be in an open position, a shear position, or a closed position;
• a main piston sealingly coupled to an activation chamber configured to contain a gas charge;
• a control piston sealingly coupled to a control chamber and configured to axially translate the ball support to move the ball to the open position, in response to a volume of fluid being delivered through a conduit;
• one or more push rods sealingly coupled to a corresponding rod port within the main piston, wherein the one or more push rods are configured to bias the ball support to move the ball to the closed position via the gas charge;
• and
• one or more ball seals configured to sealingly engage an outer surface of the ball, and isolate a first wellbore environment above the ball from a second wellbore environment below the ball when the ball is in the closed position,
• wherein the ball support is configured to linearly translate to contact the main piston,
• wherein the ball is further configured to move to the open position by the ball support axially translating and in response to a fluid pressure within the control chamber overcoming a bias of the gas charge within the activation chamber,
• wherein the main piston is configured to axially translate into the activation chamber in response to the axial transition of the ball support,
• wherein a volume within the activation chamber is decreased and a pressure of a compressible gas in the activation chamber is increased in response to the axial translation of the main piston into the activation chamber,
• wherein the fluid passage of the ball aligns with a tool passage within the valve assembly when the ball is in the open position,
• wherein the ball is further configured to move to the shear position in response to the ball support axially translating, and
• wherein the main piston is configured to contact a limit shoulder when the ball is in the shear position and in response to a reduction in fluid volume within the control chamber.