Downhole fluid pumping apparatus and method
AssigneeSchlumberger Technology Corporation
InventorsReinhart Ciglenec, Paal Kibsgaard, Steven G. Villareal
Life of this patent
Estimating the term…
Abstract
A downhole fluid pump including a pump chamber, and a piston disposed in the pump chamber so that the piston will move in one selected from a charge stroke and a discharge stroke when the piston is exposed to a differential pressure. The downhole fluid pump may form part of a formation evaluation while drilling tool.
Claims42
A downhole fluid pump for a downhole tool positioned in a wellbore penetrating a subterranean formation, comprising:
- a pump chamber positionable in fluid communication with the subterranean formation;
- a piston disposed in the pump chamber so that the piston will move in one selected from a charge stroke and a discharge stroke when the piston is exposed to a pressure differential between an internal pipe mud pressure and an annular pressure in the wellbore whereby fluid from the subterranean formation is drawn into the downhole tool.
A downhole fluid pump, comprising:
- a pump chamber;
- a hydraulic chamber;
- a piston assembly having a first piston disposed in the pump chamber and defining a first section of the pump chamber and a second section of the pump chamber, the piston assembly also having a second piston disposed in the hydraulic chamber and defining a first section of the hydraulic chamber and a second section of the hydraulic chamber, the first piston and the second piston connected by a connecting member;
- a valve in fluid communication with the pump chamber for selectively placing the pump chamber in fluid communication with at least one selected from a charge line and a discharge line;
- an internal pipe pressure isolation valve for selectively hydraulically coupling the hydraulic chamber to an internal pipe pressure;
- an annular pressure isolation valve for selectively hydraulically coupling the hydraulic chamber to an annular pressure;
- and
- a spring disposed in one of the first section of the hydraulic chamber and the second section of the hydraulic chamber and positioned to exert a force on the piston assembly,
- wherein the piston assembly is moveable with respect to the pump chamber and the hydraulic chamber.
A method of operating a fluid pump, comprising:
- operating the fluid pump in one selected from the group consisting of a charge stroke and a discharge stroke by applying an annular pressure to a first side of a piston;
- operating the fluid pump in the other of the charge stroke and the discharge stroke by applying an internal pipe mud pressure to the first side of the piston;
- and
- selectively repeating the applying the annular pressure to the first side of the piston and the applying the internal pipe mud pressure to the first side of the piston.
A formation evaluation while drilling tool, comprising:
- a drill collar;
- a fluid inlet disposed in the drill collar;
- and
- a fluid pump in fluid communication with the fluid inlet,
- wherein the fluid pump comprises
- a pump chamber;
- and
- a first piston disposed in the pump chamber so that the piston will move in one selected from a charge stroke and a discharge stroke when the piston is exposed to an internal pipe mud pressure.
A method of formation evaluation, comprising:
- establishing fluid communication between a fluid inlet in a formation evaluation tool and a formation;
- and
- drawing fluid into the tool by selectively repeating applying an annular pressure to a first side of a piston and applying an internal pipe pressure to the first side of the piston.
Dependencies are inferred from the claim text.