Hydraulic jar device
An arrangement by a hydraulic jar device, especially for use in underground wells, where the jar device is installed in a pipe string led down into the well, and designed so that e.g. a stuck object in the well may be loosened or broken up by upward or downward percussions from the jar device. The jar device is actuated by increasing the flow of drill fluid. Alternatively, the device is actuated by compression. A valve ( 27, 37, 38 ) closes off the flow of drill fluid, whereby a percussion cycle is initiated. The valve is designed so as also to seal during strong lateral accelerations.
1. A hydraulic jar device, for use in underground wells, where the jar device is installed in a pipe string led down into the well, and designed to provide upward or downward percussions from the jar device, where the jar device comprises:
a casing member,
a connector sleeve, and
a jar, the casing member and connector sleeve each having separate longitudinal through bores, while the jar has a bore and a gateway so that hydraulic liquid may pass in the jar device, and where the jar device is provided with a piston associated with a valve, comprising:
a ball, a valve seat having a curved contact surface, and a lower valve body, designed to close and open a bore during the percussion cycle, the piston valve being designed, respectively, to close off the inflowing hydraulic liquid and to open when the spring force of a tension spring exceeds the pressure from the inflowing hydraulic liquid, so that the piston will displace the jar relative to the casing member, whereby the jar exerts a force against the casing member in order to carry out the percussion, characterized in that a guide is positioned in the immediate vicinity of the valve seat and designed to prevent the ball from movement in the lateral direction of the jar device or when the jar device undergoes a strong lateral acceleration, the guide and the valve seat being made up of surface parts of the same piece of material.
2. The hydraulic jar device according to claim 1 , characterized in that the ball is adapted to seal against the valve seat.
3. A method for dislodging a stuck object in a wellbore, comprising;
positioning a downhole tool adjacent the stuck object, the downhole tool comprising:
a body having at least one fluid pathway constructed and arranged to allow fluid to selectively flow therethrough;
a valve body movable between a first position and a second position relative to the body;
a biasing member biasing the valve body in the first position to allow fluid to flow through the at least one fluid pathway; and
a movable piston having a valve seat;
a closure member for selective engagement with the valve seat, pumping fluid through the at least one fluid pathway;
urging the closure member into substantial contact with the valve seat and closing the flow of fluid through the at least one fluid pathway;
moving the piston and valve body to the second position by fluid flow, thereby compressing the biasing member;
separating the closure member from the valve seat; and
urging the valve body against the piston while returning the valve body to the first position, thereby causing the piston to exert a force against the body for dislodging the stuck object.
4. The method of claim 3 , further including preventing lateral movement of the closure member relative to the body.
5. The method of claim 3 , further comprising extending the biasing member, thereby returning the valve body to the first position.
6. The method of claim 3 , wherein the jar member is moved by the piston.
7. The method of claim 3 , wherein urging the closure member into substantial contact with the valve seat comprises compressing a second spring.
8. The method of claim 3 , wherein the force of the biasing member is greater than a hydraulic force acting on the piston.
9. The method of clam 3 , further comprising providing the jar member with an impact shoulder, the impact shoulder adapted to engage an impact area.
10. The method of claim 9 , wherein moving the piston to the second position increases the distance between the impact shoulder and the impact area.
11. The method of claim 10 , wherein exerting the force for dislodging comprises engaging the impact shoulder with the impact area.
12. A hydraulic jar device for use in a well, comprising:
a casing member having a longitudinal bore therethrough,
a piston disposed within the casing member and adapted to apply a force against the casing member, the piston having a fluid bore;
a valve body for selective engagement with the piston;
a biasing member adapted to move the valve body between a first position and a second position, wherein in the first position, the valve body is urged against the piston and the fluid bore is open, and in the second position, the biasing member is compressed and the fluid bore is closed.
13. The jar of claim 12 , wherein the force is applied against the casing member when the valve body moves from the second position to the first position.