Patent ID: 6206101
Filing Date: 2001-03-27
Classification: E21B

Abstract:
A device for overcoming friction and applying impact energy to an object stuck within an oil or gas well, in order to loosen and disengage said stuck object through the application of pressure changes to a liquid flowing within the bore of a coilable tubing or a drill string, and wherein a valve body is adapted to seal against a valve seat and shut off the liquid flow whenever the flow rate exceeds a predetermined value, thus giving rise to a build-up of pressure in the liquid flow, until a pressure fall is caused upstream of the valve body, said valve body further is adapted to maintain the closed position thereof, shutting off the liquid flow, when the flow rate exceeds a predetermined value, and that the valve body is assigned a slide adapted to open for a liquid stream past the valve body, in order to reduce the pressure in the liquid upstream of the valve body, whenever the pressure in the liquid upstream of the valve body exceeds a predetermined value, and wherein a part of the valve body is assigned a damping device, restricting the speed of the valve body during part of the movements thereof from opened to closed and from closed to opened position, and wherein the damping device comprises at least one piston in the form of a collar providing resistance against being moved within an annular space filled with liquid, said collar being provided with a flow resistor in the form of a channel.