DOWNHOLE PUMP WITH A PRESSURE SEQUENCING VALVE
A downhole pump has a master piston having a first side and a second side in a first piston chamber. The first piston chamber has a first inlet and a second inlet for alternatingly applying fluid pressure to the first side of the master piston to move the piston toward the top of a piston stroke, and to the second side of the master piston to move the piston toward the bottom of the piston stroke. A valve is carried by the master piston that relieves fluid pressure from the respective side of the master piston once the top or bottom of the stroke is reached. There is a sequencing valve with a first state that applies fluid pressure to the first inlet and a second state that applies fluid pressure to the second inlet. The sequencing valve switches between the first state and the second state once a drop in pressure occurs. A slave piston is driven by the master piston in a second piston chamber. The second piston chamber has at least one fluid inlet and at least one fluid outlet.
This relates to a downhole pump that uses a pressure sequencing valve
BACKGROUNDDownhole pumps may be hydraulically driven, such as the pump described in Canadian Patent Application No. 2,576,693 (Hoffarth) entitled “Hydraulic submersible pump with electric motor drive.”
SUMMARYThere is provided a downhole pump, comprising a master piston having a first side and a second side in a first piston chamber and a slave piston driven by the master piston in a second piston chamber. The first piston chamber comprises a first inlet and a second inlet for alternatingly applying fluid pressure to the first side of the master piston to move the piston toward the top of a piston stroke, and to the second side of the master piston to move the piston toward the bottom of the piston stroke. A valve is carried by the master piston that relieves fluid pressure from the respective side of the master piston once the top or bottom of the stroke is reached. There is a sequencing valve that has a first state that applies fluid pressure to the first inlet and a second state that applies fluid pressure to the second inlet. The sequencing valve switches between the first state and the second state once a drop in pressure occurs. The second piston chamber has at least one fluid inlet and at least one fluid outlet. The valve may be a poppet valve that opens a flow passage through the master piston. The slave piston may be a double-acting piston and the second piston chamber may have a fluid inlet and a fluid outlet on each side of the slave piston
According to another aspect, there is provided a downhole pump, comprising a master piston in a first piston chamber, a slave piston in a second piston chamber, and a travelling liquid seal carried by the slave piston that engages an inner surface of the second piston chamber. The travelling liquid creates a seal against fluid while permitting gas to pass. The second piston chamber comprises a fluid inlet and a first outlet on a first side of the slave piston and a second outlet on a second side of the slave piston, wherein the gas that passes the travelling liquid seal exits through the second outlet.
These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:
Referring to
Referring to
In some wells, gas may be present in the downhole fluids, which can cause problems in a pump if not addressed properly. Referring to
The motive fluid used to drive master piston 12 may vary, as will the means for exhausting the motive fluid. Referring to
While a liquid, such as hydraulic fluid or water, may be used to drive master piston 12, gas may also be used to drive piston 12. This may be particularly useful if the embodiment in
In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.
The following claims are to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described.
Claims
1. A downhole pump, comprising:
- a master piston having a first side and a second side in a first piston chamber, the first piston chamber comprising a first inlet and a second inlet for alternatingly applying fluid pressure to the first side of the master piston to move the piston toward the top of a piston stroke, and to the second side of the master piston to move the piston toward the bottom of the piston stroke;
- a valve carried by the master piston that relieves fluid pressure from the respective side of the master piston once the top or bottom of the stroke is reached;
- a sequencing valve having a first state that applies fluid pressure to the first inlet and a second state that applies fluid pressure to the second inlet, the sequencing valve switching between the first state and the second state once a drop in pressure occurs; and
- a slave piston driven by the master piston in a second piston chamber, the second piston chamber having at least one fluid inlet and at least one fluid outlet.
2. The downhole pump of claim 1, wherein the valve is a poppet valve that opens a flow passage through the master piston.
3. The downhole pump of claim 1, wherein the slave piston is a double-acting piston and the second piston chamber has a fluid inlet and a fluid outlet on each side of the slave piston.
4. The downhole pump of claim 1, wherein the master cylinder is driven by a gas.
5. The downhole pump of claim 1, wherein the gas expelled from the master cylinder is expelled into at least one fluid outlet of the second piston chamber.
6. The downhole pump of claim 1, further comprising a travelling liquid seal carried by the slave piston that engages an inner surface of the second piston chamber, the travelling liquid creating a seal against fluid while permitting gas to pass.
7. The downhole pump of claim 6, wherein the second piston chamber comprises a first outlet on a first side of the slave piston and a second outlet on a second side of the slave piston, wherein the gas that passes the travelling liquid seal exits through the second outlet.
8. A downhole pump, comprising:
- a piston in a piston chamber;
- a motive force for driving the piston;
- a travelling liquid seal carried by the piston that engages an inner surface of the second piston chamber, the travelling liquid creating a seal against fluid while permitting gas to pass; and
- the second piston chamber comprising a fluid inlet and a first outlet on a first side of the slave piston and a second outlet on a second side of the slave piston, wherein the gas that passes the travelling liquid seal exits through the second outlet.
Type: Application
Filed: Jul 25, 2011
Publication Date: Apr 18, 2013
Inventor: Clayton Hoffarth (Big Beaver)
Application Number: 13/805,250
International Classification: F04B 17/00 (20060101);