Claims
- 1. A drilling fluid powered drill string jar comprising:
- (a) a body comprising a length of drill string;
- (b) an elongated generally cylindrical opening situated in said body, having a first end and a second end and having an axial centerline generally parallel the centerline of said body;
- (c) a mass situated for limited axial movement in said opening and operatively associated with said opening to act as a piston therein;
- (d) a first fluid communication means to conduct drilling fluid from an upwardly continuing drill string through said body to a downwardly continuing drill string;
- (e) a second fluid communication means to conduct drilling fluid from the upstream end of said first fluid communication means to said first end of said opening;
- (f) selector valve means, situated in said body, operatively associated with said first and said second fluid communication means, to close said first fluid communication means and open said second fluid communication means in response to drilling fluid flow rate greater than a preselected limit fluid flow rate greater than a preselected limit and to function as a disabler means responsive to a preselected number of instances of drilling fluid flow rate changes, between said preselected limit to disable said jar; and
- (g) motion stop means comprising abutting surfaces on said mass and on said body situated to stop axial movement of said mass when said mass reaches the limit of said axial movement at said second end of said opening.
- 2. The apparatus of claim 1 wherein said mass is biased toward said first end of said opening.
- 3. The apparatus of claim 1 wherein said second end of said elongated cylindrical opening is in fluid communication with a vent communication means opening to the well annulus.
- 4. The apparatus of claim 1 further providing that said selector valve means is operatively associated with said first communication means arranged to inhibit flow through said first fluid communication means downstream of said second fluid communication means.
- 5. The apparatus of claim 1 further providing a relief valve responsive to pressure differential across said selector valve means, operatively associated with said second fluid communication means to open said second fluid communication pressure across said valve means is exceeded.
- 6. The apparatus of claim 5 further providing that said relief valve open said second fluid communication means to a third fluid communication means by-passing said selector valve means when fluid pressure in said second communication means exceeds a preselected amount.
- 7. The apparatus of claim 1 further providing limited fluid flow by-pass means from the first end of said opening to the second end of said opening.
- 8. The apparatus of claim 3 further providing that said opposed abutting surfaces be operatively associated with said vent communication means to close said vent communication means when said mass is at said second end of said opening.
- 9. The apparatus of claim 1 further providing that said elongated generally cylindrical opening in said body be bounded by an inner washpipe and an outer body tube.
- 10. The apparatus of claim 1 further providing that said abutting surface on said mass be on a replaceable element secured to said mass.
- 11. The apparatus of claim 1 further providing that said abutting surface in said opening be on a replaceable element secured to said body.
- 12. The apparatus of claim 5 further providing that said relief valve actuate at a higher drilling fluid pressure than the minimum drilling fluid pressure required to actuate said selector valve means.
- 13. The apparatus of claim 5 further providing that fluid displaced by movement of said relief valve be vented through a flow rate restrictor means into said first fluid communication means downstream of said selector valve means.
- 14. The apparatus of claim 1 wherein said first end of said elongated generally cylindrical opening is on the downstream end of said elongated generally cylindrical opening relative to the flow of drilling fluid through said body.
- 15. The apparatus of claim 1 wherein said first end of said elongated generally cylindrical opening is on the upstream end of said elongated generally cylindrical opening relative to the flow of drilling fluid through said body.
- 16. The apparatus of claim 1 further providing bias means to urge said mass toward said first end of said opening.
- 17. A drill string jar comprising:
- an elongated generally cylindrical body capable of functioning as a length of drill pipe, with means at each end to attach with fluid tight engagement to a drill string;
- an opening in said body extending in a direction generally parallel the longitudinal axis of said body;
- a mass situated for limited axial motion in said opening and arranged to function as a piston in said opening;
- a first fluid communication means to conduct drilling fluid from an upwardly continuing drill string, attached to said body, to a downwardly continuing drill string, attached to said body;
- a second fluid communication means to conduct drilling fluid from an upwardly continuing drill string, attached to said body, to a first end of said opening;
- a remote controlled selector valve means operatively associated with said two communication means, responsive to drilling fluid pressure manipulations of a first characteristic to close said first communication means and to open said second communication means and responsive to fluid pressure manipulations of a second characteristic to open said first communication means and to close said second communication means; and
- means situated in said body to bias said mass toward said first end of said opening.
- 18. The apparatus of claim 1 further providing a relief valve means to resist the flow of drilling fluid to said first end of said opening until drilling fluid pressure exceeds a preselected amount.
- 19. The apparatus of claim 1 further providing a bypass valve means operatively associated with the drilling fluid circuit to said first end of said opening to permit drilling fluid flow to the downwardly continuing drill string when said mass is at the second end of said opening.
- 20. The apparatus of claim 1 further providing a relief valve means in the fluid circuit to said first end of said generally cylindrical opening to admit drilling fluid to said first end of said generally cylindrical opening after the drilling fluid pressure in said first fluid communication means exceeds a preselected amount.
BACKGROUND OF THE INVENTION
This invention pertains to well drilling with fluid conducting drill strings including drill string jars. More particularly, this invention pertains to drill string jars powered by the drilling fluid to impart shock loads to the drill string to free stuck pipe and the like.
In the preferred embodiment, apparatus of this invention incorporates, as a sub-assembly, the Remote Controlled Selector Valve of the copending U.S. Pat. No. 4,655,289 issued 04/07/87. That patent, by reference, is made part of this specification.
Drill string jars conventionally used, and all known to be in current use, rely upon axial force applied to the drill string for power and actuation. Usually, rotation of the drill string, to some extent, is used to trigger the jars under stress. In some cases, the drill string is only triggered by reverse rotational force applied to the stressed drill string. With jars used near the bottom of the drill string, lifting force, in excess of the force normally required to lift the lower drill string assembly can trigger the jars. Quite often, it is undesirable to axially move the drill string to reset and activate the jars.
The following U.S. patents may be regarded as typical of tension and compression jars in common use in oil field service. These jars derive jarring power from drill string stress by allowing the tool bodies to telescope a limited amount. U.S. Pat. Nos. 2,008,743 issued July 23, 1935; 2,065,135 issued Dec. 22, 1936; 2,144,869 issued Jan. 24, 1939; 2,819,877 issued Jan. 14, 1958; 2,978,048 issued April 4, 1961; and 4,376,468 issued Mar. 15, 1983 are typical.
There are several reasons to avoid axial manipulations of the drill string jars, other than applying the essential axial loads needed to assist in the loosening action, for stuck strings, accomplished by shock loads of jars.
With a stuck drill string, axial drill string loads managable from the earth surface, often do not reach below the stuck point. Jars dependent upon drill string manipulation may not actuate below the stuck point. There is a need for jars that can operate at the first convenient assembly point above the drill head, or anywhere along the drill string.
The usual long drill string provides a powerful hydraulic circuit that is commonly still active, through the full length, during stuck string situations. In addition to being powerful, the drill string is capacitive and can store considerable fluid energy if pressure is built up before fluid power is admitted to the jars.
It is therefore an object of this invention to provide drill string jars powered by drilling fluid pressure in the drill string to impart axial shock loads to the drill string when selective manipulation of the drilling fluid flow controls are exercised at the earth surface.
It is another object of this invention to provide drill string jars powered by drilling fluid pressure to activate and reset for subsequent activation independently of axial loads or rotational manipulations of the drill string.
It is yet another object of this invention to provide a drilling fluid powered and activated drill string jar that permits normal drilling and drilling fluid flow without activating the jars.
It is still a further object of this invention to provide a drilling fluid powered drill string jar that will actuate only after a preselected fluid pressure is established in the drill string.
It is yet a further object of this invention to provide drilling fluid powered and pressure activated jars that can be arranged to jar upward or downward on the drill string.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification including the attached drawings and appended claims.
A drill string jar with a heavy piston to act as a jarring mass is powered by drilling fluid pressure arranged to propel the mass against stops on the jar body to jar the drill string. A remote control selector valve responds to drilling fluid flow manipulations of a first characteristic to shift the jar into drilling mode during which normal drilling and flow activities can be carried out without jarring the string. Drilling fluid flow manipulations of a second characteristic shifts the jar to the jarring mode. The drill string will be jarred each time the drilling fluid flow is reduced, then increased, within selected limits.
A heavy piston is situated in an axially directed opening in the jar and driven by drilling fluid pressure against stops in the distal end of the opening. A relief valve delays fluid flow from the drill string to the piston until fluid pressure energy is built up in the drill string. The relief, or pilot, valve opens rapidly to direct drilling fluid to the piston and acts more slowly to open a by-pass for drilling fluid to flow to the downwardly continuing drill string.
The jar machine elements can be arranged to direct jarring action upward or downward. Additionally, the relief valve can be arranged to activate the jar at preselected drill string pressures, permitting the use of a series of jars in the drill string assembly.
US Referenced Citations (8)
Foreign Referenced Citations (1)
| Number |
Date |
Country |
| 0933924 |
Jun 1982 |
SUX |
Patent Grant
4807709
