Boring or penetrating the earth – Below-ground impact members – Fluid-operated
Reexamination Certificate
1998-06-10
2001-02-06
Tsay, Frank (Department: 3672)
Boring or penetrating the earth
Below-ground impact members
Fluid-operated
C166S178000
Reexamination Certificate
active
06182775
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
REFERENCE TO A “MICROFICHE APPENDIX”
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to oil and gas well drilling, and more particularly to an improved downhole jar apparatus that delivers upward blows and which is activated by pumping a valving member or activator ball downhole through a tubing string or work string. Even more particularly, the present invention relates to an improved downhole jar apparatus for use in oil and gas wells that includes upper and lower pistons that are each movable between upper and lower positions, the lower piston having a valve seat and a valving member that can be moved to seal the valve seat wherein a trip mechanism separates the second valving member from the lower piston seat when a predetermined pressure value is overcome and a return mechanism returns the first piston to its upper position when the trip mechanism separates the second valving member from the lower piston seat to deliver an upward jar to the tool body.
2. General Background of the Invention
In downhole well operation, there is often a need for jarring or impact devices. For example, such a “jar” is often used in work over operations using a pipe string or work string such as a coil tubing unit or a snubbing equipment. It is sometimes necessary to provide downward jarring impact at the bottom of the work string to enable the string to pass obstructions or otherwise enter the well. During fishing operations or other operations, such as opening restriction (i.e., collapsed tubing) it is sometimes necessary to apply upward jarring or impact forces at the bottom of the string if the fishing tool or the like becomes stuck.
In prior U.S. Pat. No. 3,946,819, naming the applicant herein as patentee, there is disclosed a fluid operated well tool adapted to deliver downward jarring forces when the tool encounters obstructions. The tool of my prior U.S. Pat. No. 3,946,819, generally includes a housing with a tubular stem member telescopically received in the housing for relative reciprocal movement between a first terminal position and a second terminal position in response to fluid pressure in the housing. The lower portion of the housing is formed to define a downwardly facing hammer and the stem member includes an upwardly facing anvil which is positioned to be struck by the hammer. The tool includes a valve assembly that is responsive to predetermined movement of the stem member toward the second terminal position to relieve fluid pressure and permit the stem member to return to the first terminal position. When the valve assembly relieves fluid pressure, the hammer moves into abrupt striking contact with the anvil. The tool of prior U.S. Pat. No. 3,946,819, is effective in providing downward repetitive blows. The tool of the '819 patent will not produce upwardly directed blows.
In prior U.S. Pat. No. 4,462,471, naming the applicant herein as patentee, there is provided a bidirectional fluid operated jarring apparatus that produces jarring forces in either the upward or downward direction. The jarring apparatus was used to provide upward or downward impact forces as desired downhole without removing the tool from the well bore for modification. The device provides downward jarring forces when the tool is in compression, as when pipe weight is being applied downwardly on the tool, and produces strong upward forces when is in tension, as when the tool is being pulled upwardly.
In U.S. Pat. No. 4,462,471, there is disclosed a jarring or drilling mechanism that may be adapted to provide upward and downward blows. The mechanism of the '471 patent includes a housing having opposed axially spaced apart hammer surfaces slidingly mounted within the housing between the anvil surfaces. A spring is provided for urging the hammer upwardly.
In general, the mechanism of the '471 patent operates by fluid pressure acting on the valve and hammer to urge the valve and hammer axially downwardly until the downward movement of the valve is stopped, preferably by the full compression of the valve spring. When the downward movement of the valve stops, the seal between the valve and the hammer is broken and the valve moves axially upwardly. The direction jarring of the mechanism of the '471 patent is determined by the relationship between the fluid pressure and the strength of the spring that urges the hammer upwardly. Normally, the mechanism is adapted for upward jarring. When the valve opens, the hammer moves upwardly to strike the downwardly facing anvil surface of the housing.
BRIEF SUMMARY OF THE INVENTION
The downhole jar apparatus for use in oil and gas wells provides an improved construction that delivers upward blows only. The apparatus can be activated by pumping a valving member (e.g., ball) downhole via a coil tubing unit, work string, or the like.
The present invention thus provides an improved downhole jar apparatus for use in oil and gas wells that includes an elongated tool body that is supportable by an elongated work string such as a coil tubing unit. The tool body provides an upper end portion that attaches to the coil tubing unit with a commercially available sub for an example, and a lower end portion that carries a working member. Such a working member can include for example, a pulling tool to extract a fish, down hole retrievable controls, a gravel pack or a safety jar, a motor or directional steering tool.
The tool body has a longitudinal flow bore that enables fluid to flow through the tool body from the upper end to the lower end.
An upper piston (first piston) is slidably mounted within the tool body bore at the upper end portion thereof. The upper piston is movable between upper and lower positions and provides a valve seat.
A lower piston (second piston) is mounted in the tool body in sliding fashion below the upper piston and is also movable between upper and lower positions. The lower piston also provides a valve seat. A first valving member preferably in the form of a ball valving member is provided for sealing the valve seat of the upper piston.
The first valving member is preferably pumped downhole via the coil tubing unit or work string using fluid flow to carry it to the valve seat of the upper piston. A second valving member in the form of an elongated dart is disposed in between the upper and lower pistons. The second valving member has a lower valving end portion that can form a seat with the lower piston seat.
A trip mechanism is provided for separating the second valving member from the lower piston seat when a predetermined hydrostatic pressure value above the lower piston is overcome by compression of a spring portion of the trip mechanism.
A return mechanism returns the first piston to its upper position when the trip mechanism separates the second valving member from the lower piston seat.
The tool body has an anvil portion positioned above the lower piston for receiving blows from the lower piston when it rapidly returns to its upper position, once separated from the second valving member.
The tool body can include upper and lower tool body sections attached together end to end with a slip joint. This allows the force of upward blows delivered by the piston to exceed the tension applied from the surface through the tubing string.
A tappet can be provided above the first piston, the tappet and first upper piston being separately movable members with a beveled seat interface provided at the connection between the bottom of the upper piston and the top of the tappet.
The tappet is used to momentarily interrupt fluid flow when the second or dart valving member fires upwardly. This interruption of fluid flow contributes to the rapid upward movement of the lower piston so that it can impact the tool body providing an upward jar.
REFERENCES:
patent: 3735827 (1973-05-01), Berryman
patent: 3851717 (1974-12-01), Berryman
patent: 3946819 (1976-03-01), Hipp
patent: 4059167 (1977-11-01), Berryman
patent: 4361195 (1982-11-
Baker Hughes Incorporated
Tsay Frank
LandOfFree
Downhole jar apparatus for use in oil and gas wells does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Downhole jar apparatus for use in oil and gas wells, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Downhole jar apparatus for use in oil and gas wells will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2591032