System for pulse-injecting fluid into a borehole
First Claim
1. Tool having an operational capability to superimpose pulses onto a pressurized stream of fluid being injected into a ground formation, wherein:
- 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, in which fluid is stored at accumulator-pressure;
the tool includes a piston, which is connected to the pulse-valve-member;
the tool includes an area-divider, relative to which the piston is movable between a contact-position and a clear-position;
the piston has an accumulator-surface and an opposed formation-surface, and the tool is so structured that, the pulse-valve being open;
(a) accumulator-pressure acting on the accumulator-surface urges the piston to its clear-position; and
(b) formation-pressure acting on the formation-surface urges the piston to its contact-position;
the tool includes structure that exerts a biassing-force on the piston in the direction to urge the piston towards the contact-position;
the tool is so structured that, the piston being in the contact-position;
(a) the accumulator-surface of the piston now makes sealing contact with the area-divider, thereby creating a divider-seal;
(b) the divider-seal sealingly divides the area of the accumulator-surface of the piston into two sub-areas, being area-A and area-B;
(c) the divider-seal, and the tool as a whole, are so structured as to enable the pressure to which area-A is exposed to be substantially different from the pressure to which area-B is exposed;
(d) only area-A of the accumulator-surface , and not area-B, is exposed to accumulator-pressure;
(e) when the pressure differential between accumulator-pressure and formation-pressure (PDAF) exceeds an upper trigger level, forces on the piston due to the PDAF acting over the area-A now exceed the biassing-force on the piston, whereby the piston now moves clear of the area-divider, towards the clear-position;
the tool is so structured that, the piston being in the clear-position;
(a) area-A and area-B are not now sealingly separated by the area-divider, but are now 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 force of sufficient magnitude to move the piston and to move the valve-member to the valve-open position.
1 Assignment
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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.
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Citations
14 Claims
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1. Tool having an operational capability to superimpose pulses onto a pressurized stream of fluid being injected 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, in which fluid is stored at accumulator-pressure; the tool includes a piston, which is connected to the pulse-valve-member; the tool includes an area-divider, relative to which the piston is movable between a contact-position and a clear-position; the piston has an accumulator-surface and an opposed formation-surface, and the tool is so structured that, the pulse-valve being open; (a) accumulator-pressure acting on the accumulator-surface urges the piston to its clear-position; and (b) formation-pressure acting on the formation-surface urges the piston to its contact-position; the tool includes structure that exerts a biassing-force on the piston in the direction to urge the piston towards the contact-position; the tool is so structured that, the piston being in the contact-position; (a) the accumulator-surface of the piston now makes sealing contact with the area-divider, thereby creating a divider-seal; (b) the divider-seal sealingly divides the area of the accumulator-surface of the piston into two sub-areas, being area-A and area-B; (c) the divider-seal, and the tool as a whole, are so structured as to enable the pressure to which area-A is exposed to be substantially different from the pressure to which area-B is exposed; (d) only area-A of the accumulator-surface , and not area-B, is exposed to accumulator-pressure; (e) when the pressure differential between accumulator-pressure and formation-pressure (PDAF) exceeds an upper trigger level, forces on the piston due to the PDAF acting over the area-A now exceed the biassing-force on the piston, whereby the piston now moves clear of the area-divider, towards the clear-position; the tool is so structured that, the piston being in the clear-position; (a) area-A and area-B are not now sealingly separated by the area-divider, but are now 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 force of sufficient magnitude to move the piston and to move the valve-member to the valve-open position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification