Abstract: Fluid is produced from a well that is equipped with a plunger lift system. The plunger lift system includes a plunger that is inserted into production tubing that is installed in the well. Liquid from a surrounding formation accumulates on top of the plunger. The liquid accumulation on the plunger is monitored. Lift gas is injected into the production tubing below the plunger to lift the plunger and accumulated liquid to surface. A wellhead assembly at surface directs the accumulated liquid away from the well, and injection of the lift gas is suspended to allow the plunger to drop back to its initial position. The timing of the lift gas injection is based on monitoring liquid accumulation, and also to maximize production from the well.

Abstract: A lift gas injection system that is used for introducing lift gas into a stream of production fluid includes a lift gas injection valve. A pressure protection system guards the injection valve against external overpressure by blocking communication to inside the injection valve housing when ambient pressure exceeds a set pressure. Communication is blocked by moving a valve member so that it obstructs flow through an opening in the housing. The system includes pressure actuated valve which has a platen mounted to an end of a bellows, and a valve member coupled to the platen. Surface area is reduced on the bellows side of the platen that creates a force imbalance on the platen from applied ambient pressure. At the set pressure the force imbalance moves the platen, and which pushes the valve member against the opening. A compressible pressure compensator inside the injection valve protects against internal overpressure.

Abstract: A lift gas injection system that is used for introducing lift gas into a stream of production fluid includes a lift gas injection valve. A pressure protection system guards the injection valve against external overpressure by blocking communication to inside the injection valve housing when ambient pressure exceeds a set pressure. Communication is blocked by moving a valve member so that it obstructs flow through an opening in the housing. The system includes pressure actuated valve which has a platen mounted to an end of a bellows, and a valve member coupled to the platen. Surface area is reduced on the bellows side of the platen that creates a force imbalance on the platen from applied ambient pressure. At the set pressure the force imbalance moves the platen, and which pushes the valve member against the opening. A compressible pressure compensator inside the injection valve protects against internal overpressure.

Abstract: A method of estimating a real time production flowrate from a well by estimating a real time flowrate of a marker fluid in the well, and comparing the estimated flowrate with a baseline marker fluid flowrate; where the baseline marker fluid flowrate correlates to baseline production fluid flowrate. The baseline marker fluid flowrate is obtained by introducing an amount of a marker fluid in the well, monitoring the time over which the marker fluid travels a set distance, and estimating a flowrate of the marker fluid based on the monitored time and amount of marker fluid. The real time production flowrate is obtained by extrapolating the baseline production fluid flowrate by an amount derived from a comparison of the baseline and real time marker fluid flow rates.

Abstract: Fluid is produced from a well that is equipped with a plunger lift system. The plunger lift system includes a plunger that is inserted into production tubing that is installed in the well. Liquid from a surrounding formation accumulates on top of the plunger. The liquid accumulation on the plunger is monitored. Lift gas is injected into the production tubing below the plunger to lift the plunger and accumulated liquid to surface. A wellhead assembly at surface directs the accumulated liquid away from the well, and injection of the lift gas is suspended to allow the plunger to drop back to its initial position. The timing of the lift gas injection is based on monitoring liquid accumulation, and also to maximize production from the well.

Abstract: A method of estimating a real time production flowrate from a well by estimating a real time flowrate of a marker fluid in the well, and comparing the estimated flowrate with a baseline marker fluid flowrate; where the baseline marker fluid flowrate correlates to baseline production fluid flowrate. The baseline marker fluid flowrate is obtained by introducing an amount of a marker fluid in the well, monitoring the time over which the marker fluid travels a set distance, and estimating a flowrate of the marker fluid based on the monitored time and amount of marker fluid. The real time production flowrate is obtained by extrapolating the baseline production fluid flowrate by an amount derived from a comparison of the baseline and real time marker fluid flow rates.

Abstract: An unflapped envelope (60) is fed, with its crease line trailing, along a path (42) from an envelope feeder and between the rollers of a reversibly driveable roller pair (43), for onward transfer to, for example, an insertion station. When the crease line reaches a predetermined point in front of the roller pair (43), the drive is reversed and the envelope with the crease line leading directed along a flapper path, including a deflecting surface 46, to a flapping chamber or zone (47), at least until the flap (61) is engageable by flapper blade means (44;44a). The drive is then reversed again and the envelope driven back along the flapper path, a flap opening surface (49) of a flapper blade (44) or a pair of flapper blade elements (44a), causing the flap (61) to be stripped from the body of the envelope (60) as it exits the flapping zone, and proceeds to the insertion station.