Disclosed is a method and system for fluid flow optimization within a wellbore for gas-lift operations and control of slug flows within the wellbore by utilizing a plurality of electronically controlled valves coupled to a tubing string. Selective actuation of the valves includes incremental opening or closing of an individual valve between a fully open, fully closed, or partial opening of a particular valve. Pressure measurements inside and outside of the tubing string are measured in real-time near the valve to help maintain the desired pressure distribution within the wellbore and to measure and control a pressure differential at a selected valve. Actuation of the valves may be electronically controlled at a remote location by electronic command signals or may be performed automatically by the downhole valves with or without input by a remote system.

An annulus safety valve assembly for controlling gas flow in a wellbore annulus that includes a passage, a check valve in the passage, and an actuator that is selectively changed between first and second states. The actuator is bi-stable, and requires no energy to remain in either state. When the actuator is put into one of the states, the check valve configuration is changed from one way flow to two way flow. Reconfiguring the check valve into the two way flow configuration vents lift gas from inside the annulus that is below the check valve.

Toe valves comprising a bore, a first sub, a second sub, and a housing. The bore extends through the valve. The first sub has separable elements. The separable elements comprise a first sub element and a sleeve element. The first sub element and sleeve element are joined by a relatively weak bridging portion adapted to break in a controlled manner in response to fluid pressure between the first sub element and the sleeve element. They thereby form an integral component comprised of the separable elements. The housing has a port and couples the first sub element and second sub.

A method for lifting a tubular string from a wellbore includes cutting the tubular string at a selected depth in the wellbore. A check valve is disposed in the tubular string above the selected depth. An interior of the tubular string is pressurized with gas to displace liquid in the tubing through the check valve. The tubular string is lifted, and a portion of the tubular string extending out of the wellbore is cut.

A method for lifting a tubular string from a wellbore includes cutting the tubular string at a selected depth in the wellbore. A check valve is disposed in the tubular string above the selected depth. An interior of the tubular string is pressurized with gas to displace liquid in the tubing through the check valve. The tubular string is lifted, and a portion of the tubular string extending out of the wellbore is cut.

A valve for use in a wellbore includes a replaceable choke device that is threaded into at least one opening formed through a sidewall of a tubular housing of the valve. The choke device is sealable on the sidewall of the tubular housing with an elastomeric sealing component, and the choke device controls at least one of fluid pressure within the tubular string and a pressure drop across the valve. The valve also includes a flow sleeve carried by the tubular housing for movement relative thereto between a first position in which fluid flow s permitted across the valve, a second position in which the flow sleeve prevents fluid flow across the valve, and a third position in which the flow sleeve is locked in place relative to the tubular housing by a lock ring.

A safety valve includes a housing having a bore, a flow tube, and a valve closure member. The flow tube resides in the bore, is configured to move telescopically within the bore, and is adapted to shift the valve closure member between a closed position and an open position. The safety valve also includes an annular section between an inner surface of the housing and an outer surface of the flow tube, and means for preventing fluid flowing through the bore from entering the annular section.

Provided is a communications sub. The communications sub, in one aspect, includes a fluid chamber, and a pressure-activated indexing device positioned within the fluid chamber, the pressure-activated indexing device including a lock mandrel configured to incrementally move between an engaged state and a disengaged state when subjected to two or more pressure cycles. The communications sub, in accordance with one aspect, further includes a latch body positioned in the fluid chamber, the latch body configured to be fixed in place by the lock mandrel and close a fluid path from the fluid chamber to a control line when the lock mandrel is in the engaged state, and configured to be allowed to move and open the fluid path from the fluid chamber to the control line when the lock mandrel is in the disengaged state.

A modular downhole packer includes a valve body, which includes a threaded coupler adapted to couple to a tubular and a valve assembly. The packer includes a packer element assembly, which includes a first end coupler, the first end coupler mechanically coupled to the valve body; a packer element; and a second end coupler. The packer includes a floating seal element mechanically coupled to the second end coupler, the floating seal element including a seal extension. The packer includes a floating end anchor. The floating end anchor includes a compression seal housing, the compression seal housing including an outer sealing surface positioned within the seal extension of the second end coupler; a compression seal positioned within a seal pocket formed in the compression seal housing; and an anchor body, the anchor body threadedly coupled to the seal pocket of the compression seal housing, the anchor body abutting the compression seal.

Provided, in one aspect, is a downhole torque limiter, comprising a tubular housing; a pipe positioned within the tubular housing, the pipe transitioning from a larger inside diameter (ID.sub.L) to a smaller inside diameter (ID.sub.S), thereby forming a venturi profile having a first pressure zone (Z.sub.1) and a second pressure zone (Z.sub.2); a tubular valve plate radially positioned between the tubular housing and the pipe and rotationally fixed with the pipe; a lower sub rotationally fixed relative to the tubular housing and rotationally coupled to the tubular valve plate via a clutch mechanism; and a valve assembly positioned within a longitudinal opening extending along at least a portion of a sidewall of the tubular valve plate, the valve assembly configured to be activated by a pressure drop created by fluid flowing through the venturi profile.