SYSTEM FOR PULSE-INJECTING FLUID INTO A BOREHOLE
First Claim
1. Tool for pulse-injecting fluid into a ground formation, wherein:
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the tool includes a pulse-valve, having a pulse-valve-member that is movable between a valve-closed position and a valve-open position;
the tool includes an accumulator, for storing pressurized fluid that is to be pulse-injected into the ground formation;
the tool includes a piston, which is connected to the pulse-valve-member;
the piston has an accumulator-surface and an opposed formation-surface, and the tool is so structured that, in operation, the accumulator-surface is exposed to accumulator-pressure, and the formation-surface is exposed to formation-pressure;
the pressure differential between the accumulator-pressure and the formation-pressure is termed the PDAF;
the tool includes an area-divider, relative to which the piston is movable between a contact-position and a clear-position;
the tool includes a biasing-means, which exerts a biasing-force on the piston in the direction to urge the piston towards its contact-position;
the tool is so structured that, the piston being in its contact-position;
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(a) the accumulator-surface of the piston now makes sealing contact with the area-divider;
(b) the area-divider sealingly divides the area of the accumulator-surface of the piston into two sub-areas, being area-A and area-B;
(c) the area-divider keeps area-A sealingly separated from area-B, to the extent that fluid pressure in area-A of the accumulator-surface of the piston can be substantially different from fluid pressure in area-B;
(d) only area-A of the accumulator surface is exposed to the accumulator-pressure, area-B being exposed to a lower pressure;
(e) when the PDAF exceeds an upper trigger level, forces on the piston due to the PDAF acting over the area-A now exceed forces on the piston due to the biasing-means, whereby the piston now moves clear of the area-divider, towards its clear-position;
the tool is so structured that, the piston having moved to its clear-position;
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(a) area-A and area-B are not now sealingly separated by the area-divider, but are connected;
(b) whereby the accumulator-pressure now suddenly acts over the sum of area-A and area-B together;
(c) whereupon the piston now is subjected to a sudden large force that acts to move the piston and to move the valve-member to its open-position.
1 Assignment
0 Petitions
Accused Products
Abstract
For injecting e.g. water into ground formation around a borehole, and for superimposing pulses onto the outflow of the injected water, it is important that the pulses have a rapid rise-time. A piston is connected to a pulse-valve of the tool. A bias spring urges the piston towards its closed position. The piston is urged towards the open position by a differential PDAF between the supplied accumulator-pressure and the in-ground formation-pressure. When the pulse-valve is open, the PDAF is falling, until the force of the spring closes the pulse-valve. Then the PDAF rises, but now the PDAF acts over only a small area of the piston. When the PDAF is high enough to ease the pulse-valve open, suddenly the whole area of the piston is exposed to the PDAF, whereby the pulse-valve opens violently.
37 Citations
3 Claims
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1. Tool for pulse-injecting fluid into a ground formation, wherein:
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the tool includes a pulse-valve, having a pulse-valve-member that is movable between a valve-closed position and a valve-open position; the tool includes an accumulator, for storing pressurized fluid that is to be pulse-injected into the ground formation; the tool includes a piston, which is connected to the pulse-valve-member; the piston has an accumulator-surface and an opposed formation-surface, and the tool is so structured that, in operation, the accumulator-surface is exposed to accumulator-pressure, and the formation-surface is exposed to formation-pressure; the pressure differential between the accumulator-pressure and the formation-pressure is termed the PDAF; the tool includes an area-divider, relative to which the piston is movable between a contact-position and a clear-position; the tool includes a biasing-means, which exerts a biasing-force on the piston in the direction to urge the piston towards its contact-position; the tool is so structured that, the piston being in its contact-position;
—(a) the accumulator-surface of the piston now makes sealing contact with the area-divider; (b) the area-divider sealingly divides the area of the accumulator-surface of the piston into two sub-areas, being area-A and area-B; (c) the area-divider keeps area-A sealingly separated from area-B, to the extent that fluid pressure in area-A of the accumulator-surface of the piston can be substantially different from fluid pressure in area-B; (d) only area-A of the accumulator surface is exposed to the accumulator-pressure, area-B being exposed to a lower pressure; (e) when the PDAF exceeds an upper trigger level, forces on the piston due to the PDAF acting over the area-A now exceed forces on the piston due to the biasing-means, whereby the piston now moves clear of the area-divider, towards its clear-position; the tool is so structured that, the piston having moved to its clear-position;
—(a) area-A and area-B are not now sealingly separated by the area-divider, but are connected; (b) whereby the accumulator-pressure now suddenly acts over the sum of area-A and area-B together; (c) whereupon the piston now is subjected to a sudden large force that acts to move the piston and to move the valve-member to its open-position. - View Dependent Claims (2, 3)
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Specification