Apparatus and method for reducing gas lock in downhole pumps

A downhole pump, comprising:

• a) a barrel having first and second ends, with a first one-way valve located adjacent to the second end, the barrel comprising a vent port at a location intermediate the first end and the first one-way valve;
• b) a plunger having first and second ends and being located inside of the barrel such that the first one-way valve is closer to the plunger second end than to the plunger first end, the plunger capable of reciprocating inside of the barrel, the plunger has a second one-way valve, a compression chamber being formed between the first one-way valve and the second one-way valve;
• c) a seal between the plunger and the barrel, the seal located between the vent port and the barrel first end;
• d) a clearance between the plunger and the barrel, the clearance located between the seal and the plunger second end so as to communicate with the compression chamber and so as to communicate with the vent port, wherein gas in the compression chamber can escape the barrel through the clearance and the vent port;
• e) a hold-down coupled to the barrel for coupling the barrel inside of the tubing, the vent port in the barrel located downhole of the hold-down.

A downhole pump, comprising:

• a) a barrel having first and second ends, with a first one-way valve located adjacent to the second end, the barrel comprising a vent port at a location intermediate the first end and the first one-way valve;
• b) a plunger having first and second ends and being located inside of the barrel such that the first one-way valve is closer to the plunger second end than to the plunger first end, the plunger capable of reciprocating inside of the barrel, the plunger has a second one-way valve, a compression chamber being formed between the first one-way valve and the second one-way valve;
• c) a seal between the plunger and the barrel, the seal located between the vent port and the barrel first end;
• d) a clearance between the plunger and the barrel, the clearance located between the seal and the plunger second end so as to communicate with the compression chamber and so as to communicate with the vent port, wherein gas in the compression chamber can escape the barrel through the clearance and the vent port;
• e) the pump is a tubing pump, the barrel being structured and arranged to be an extension of tubing.

A downhole pump, comprising:

• a) a barrel having first and second ends, with a first one-way valve located adjacent to the second end, the barrel comprising a vent port at a location intermediate the first end and the first one-way valve;
• b) a plunger having first and second ends and being located inside of the barrel such that the first one-way valve is closer to the plunger second end than to the plunger first end, the plunger capable of reciprocating inside of the barrel, the plunger has a second one-way valve, a compression chamber being formed between the first one-way valve and the second one-way valve;
• c) a seal between the plunger and the barrel, the seal located between the vent port and the barrel first end;
• d) a clearance between the plunger and the barrel, the clearance located between the seal and the plunger second end so as to communicate with the compression chamber and so as to communicate with the vent port, wherein gas in the compression chamber can escape the barrel through the clearance and the vent port;
• e) a third one-way valve located in the plunger between the second one-way valve and the plunger first end, the plunger having a vent port located between the second and third one-way valves.

A method of venting free gas in a downhole pump in a well having a casing, the pump produces fluid into tubing that extends from the pump to the surface, the pump comprising a barrel with a first one-way valve and a plunger with a second one-way valve, there being a compression chamber located between the first and second one-way valves, comprising the steps of:

• a) reciprocating the plunger inside of the barrel so as to expand and contract the compression chamber between the first and second one-way valves;
• b) as the compression chamber expands, allowing fluid to flow into the compression chamber;
• c) as the compression chamber contracts, venting free gas in the compression chamber past a portion of the plunger and out of the barrel and out of the tubing into a space between the tubing and the casing while maintaining a seal between another portion of the plunger and the barrel;
• d) when the compression chamber empties of free gas while continuing to contract the compression chamber, pressurizing the fluid in the compression chamber to open the second one-way valve.

A method of venting free gas in a downhole pump in a well comprising a barrel with a first one-way valve and a plunger with a second one-way valve and a third one-way valve, there being a compression chamber located between the first and second one-way valves, with the second one-way valve located between the compression chamber and the third one-way valve, comprising the steps of:

• a) reciprocating the plunger inside of the barrel so as to expand and contract the compression chamber between the first and second one-way valves;
• b) as the compression chamber expands, allowing fluid to flow into the compression chamber;
• c) as the compression chamber contracts, venting free gas in the compression chamber past a portion of the plunger and out of the barrel while maintaining a seal between another portion of the plunger and the barrel;
• d) when the compression chamber empties of free gas while continuing to contract the compression chamber, pressurizing the fluid in the compression chamber to open the second one-way valve;
• e) venting the space between the second and third one-way valves out of the barrel when the compression chamber is near full contraction.