Patent ID: 9194211
Filing Date: 2015-11-24
Classification: E21B,F16K

Abstract:
1. Tool for pulse-injecting liquid from a borehole out into the surrounding ground-formation, wherein: the tool includes a pulse-valve; the pulse-valve includes a valve-seat and a relatively-movable valve-member; the tool includes a pair of magnet-elements, one connected to the valve-seat, the other to the valve-member; the magnet-elements are arranged in the tool for magnetic attraction; the magnet-elements urge the pulse-valve closed; the tool is so configured that the two magnet-elements are close together when the pulse-valve is closed, and apart from each other when the pulse-valve is open; whereby, when the pulse-valve opens, the magnetic attraction between the two magnet-elements decreases; the tool includes a supply of liquid, stored in an accumulator at accumulator-pressure; liquid in the ground formation is at formation-pressure; the pressure differential between accumulator-pressure and formation-pressure is termed the PDAF; the tool is so configured that, during operation: (a) when the pulse-valve is closed, the PDAF is increasing towards a high-threshold at which the Pulse-valve opens; and (b) when the pulse-valve is open, the PDAF is decreasing towards a low-threshold at which the pulse-valve closes; the movable valve-member is a component of a movable-unit, which is movable relative to a fixed housing of the tool; one of the magnet-elements is integral with the movable-unit, and the other is integral with the fixed housing; the tool is so configured that, during operation, the PDAF urges the movable-unit in the direction to open the pulse-valve with a force termed the PDAF-force; the PDAF-force is termed the closed-PDAF-force when the Pulse-valve is closed; the PDAF-force is termed the open-PDAF-force when the Pulse-valve is open; the magnet-elements bias the valve-member in the direction to close the pulse-valve with a force termed the magnet-force; the magnet-force is termed the closed-magnet-force when the pulse-valve is closed; the magnet-force is termed the open-magnet-force when the Pulse-valve is open; the high-threshold of the PDAF is the magnitude of the increasing PDAF at which the closed-PDAF-force equals the closed-magnet-force; the low-threshold of the PDAF is the magnitude of the decreasing PDAF at which the open-magnet-force equals the open-PDAF-force; whereby the pulse-valve cycles automatically between open and closed.