Anti-gas lock valve for a reciprocating downhole pump

A method of overcoming gas-lock to resume normal fluid pumping in a pump having a barrel and a plunger within that reciprocates uphole on an upstroke and downhole on a downstroke, a barrel inlet receiving a charge of fluid into a pump chamber in the barrel through a standing valve at a downhole end thereof, and the plunger having the travelling valve at a downhole end thereof, the method comprising:

• on the downstroke, compressing gassy fluid in the pump chamber and opening a chamber valve between the pump chamber and a staging chamber located at a downhole end of the traveling valve for receiving at least a portion of the compressed and gassy fluid therein;
• on the upstroke, closing the chamber valve for sealably retaining the at least a portion of compressed and gassy fluid therein while drawing an increment of fluid through the standing valve into the pump chamber;
• and
• repeating subsequent downstroke and upstroke cycles wherein on each downstroke, a pressure of the compressed gassy fluid in the pump chamber increases until it exceeds the hydrostatic head uphole of the travelling valve for resumption of normal fluid pumping.