Downhole piston pump and method of operation
First Claim
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1. A method, comprising:
- supplying a hydraulic pressure via a hydraulic fluid to a positive displacement pump of a downhole tool to actuate a two-stroke piston, having a first head positioned in a first cylinder and a second head positioned in a second cylinder, to displace other fluid at least partially through the downhole tool, wherein the first head divides the first cylinder into a first pump chamber and a first fluid chamber and wherein the second head divides the second cylinder into a second pump chamber and a second fluid chamber;
moving the piston in a first stroke direction by supplying the hydraulic fluid to the first pump chamber;
detecting a pressure increase caused by the piston abutting an inner wall of the first cylinder to foreclose a volume of the first fluid chamber;
actuating a valve, in response to detecting the pressure increase, to reverse the direction of the piston by supplying the hydraulic fluid to the second pump chamber.
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Abstract
A method, according to one or more aspects of the present disclosure, for operating a positive displacement pump of a downhole tool comprises supplying a hydraulic pressure to the pump to actuate a two-stroke piston to displace fluid at least partially through the downhole tool; moving the piston in a first stroke direction; and reversing the direction of the piston upon completion of the first stroke of the piston. Completion of a stroke may comprise a head of the piston substantially abutting an end wall of a chamber of the pump.
23 Citations
20 Claims
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1. A method, comprising:
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supplying a hydraulic pressure via a hydraulic fluid to a positive displacement pump of a downhole tool to actuate a two-stroke piston, having a first head positioned in a first cylinder and a second head positioned in a second cylinder, to displace other fluid at least partially through the downhole tool, wherein the first head divides the first cylinder into a first pump chamber and a first fluid chamber and wherein the second head divides the second cylinder into a second pump chamber and a second fluid chamber; moving the piston in a first stroke direction by supplying the hydraulic fluid to the first pump chamber; detecting a pressure increase caused by the piston abutting an inner wall of the first cylinder to foreclose a volume of the first fluid chamber; actuating a valve, in response to detecting the pressure increase, to reverse the direction of the piston by supplying the hydraulic fluid to the second pump chamber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus, comprising:
a pump assembly for pumping a fluid at least partially through a downhole tool, the assembly comprising; a two-stroke displacement unit including a piston having a first piston head positioned in a first cylinder and a second piston head positioned in a second cylinder; a first pump chamber formed between the first piston head and a distal wall of the first cylinder; a second pump chamber formed between the second piston head and a distal wall of the second cylinder; a first fluid chamber formed between the first piston head an inner wall of the first cylinder; a second fluid chamber formed between the second piston head and an inner wall of the second cylinder; a valve actuatable to reverse the direction of the piston; a control system selectively providing hydraulic fluid via a hydraulic circuit to the first pump chamber to move the piston in a first stroke direction and to the second pump chamber to move the piston in an opposite stroke direction, wherein the control system is configured to actuate the valve to reverse the stroke direction in response to detecting a pressure increase caused by the first piston head abutting the inner wall of the first cylinder to foreclose a volume of the first fluid chamber; and a dampening device connected with the displacement unit to reduce the speed of the piston as it approaches completion of the stroke. - View Dependent Claims (13, 14, 15)
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16. A method, comprising:
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disposing a downhole tool having a pump assembly hydraulically connected to a flow line extending at least partially through the downhole tool in a borehole, the pump assembly comprising; a two-stroke displacement unit including a piston having a first piston head positioned in a first cylinder and a second piston head positioned in a second cylinder; a first pump chamber formed between the first piston head and a distal wall of the first cylinder; a second pump chamber formed between the second piston head and a distal wall of the second cylinder; a first fluid chamber formed between the first piston head an inner wall of the first cylinder; a valve actuatable to reverse the direction of the piston; and a control system selectively providing hydraulic fluid via a hydraulic circuit to the first pump chamber to move the piston in a first stroke direction and to the second pump chamber to move the piston in an opposite stroke direction in response to the hydraulic pressure of the hydraulic fluid; detecting a pressure increase caused by the first piston head abutting the inner wall of the first cylinder to foreclose a volume of the first fluid chamber; and actuating the valve, in response to detecting the pressure increase, to reverse the direction of the piston stroke. - View Dependent Claims (17, 18, 19, 20)
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Specification