CA1233166A - Mechanical well jar - Google Patents
Mechanical well jarInfo
- Publication number
- CA1233166A CA1233166A CA000485835A CA485835A CA1233166A CA 1233166 A CA1233166 A CA 1233166A CA 000485835 A CA000485835 A CA 000485835A CA 485835 A CA485835 A CA 485835A CA 1233166 A CA1233166 A CA 1233166A
- Authority
- CA
- Canada
- Prior art keywords
- jar
- notches
- members
- move
- rollers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B31/00—Fishing for or freeing objects in boreholes or wells
- E21B31/107—Fishing for or freeing objects in boreholes or wells using impact means for releasing stuck parts, e.g. jars
Abstract
ABSTRACT OF THE DISCLOSURE
A mechanical well jar is disclosed having inner and outer tubular members movable longitudinally relative to each other a limited distance for connecting in a pipe string. Annular shoulders on the members engage to limit the relative longitudinal movement of the members. A
plurality of laterally spaced, arcuate cam plates are attached to the inner surface of the outer member. Each plate has a laterally extending U-shaped notch opening into the space between the plates and formed with curved outward-ly flaring sidewalls. Rollers are mounted on the outer surface of the inner member to extend into the spaces between the cam plates for movement into the U-shaped notches to hold the members from longitudinal movement relative to each other. Resilient means urge the members to rotate in the direction to move the rollers into the notches and allow the rollers to move out of the notches when a longitudinal force is imposed on the jar through the string sufficient for the flared sidewalls of the notches to provide a lateral component of force on the rollers suffi-cient to overcome the force of the resilient means and move the rollers out of the notches. This allows the tubular members to move longitudinally relative to each other until the annular shoulders stop such movement and transfer the energy stored in the drill pipe to the other member and to the stuck pipe or fish below the jar.
A mechanical well jar is disclosed having inner and outer tubular members movable longitudinally relative to each other a limited distance for connecting in a pipe string. Annular shoulders on the members engage to limit the relative longitudinal movement of the members. A
plurality of laterally spaced, arcuate cam plates are attached to the inner surface of the outer member. Each plate has a laterally extending U-shaped notch opening into the space between the plates and formed with curved outward-ly flaring sidewalls. Rollers are mounted on the outer surface of the inner member to extend into the spaces between the cam plates for movement into the U-shaped notches to hold the members from longitudinal movement relative to each other. Resilient means urge the members to rotate in the direction to move the rollers into the notches and allow the rollers to move out of the notches when a longitudinal force is imposed on the jar through the string sufficient for the flared sidewalls of the notches to provide a lateral component of force on the rollers suffi-cient to overcome the force of the resilient means and move the rollers out of the notches. This allows the tubular members to move longitudinally relative to each other until the annular shoulders stop such movement and transfer the energy stored in the drill pipe to the other member and to the stuck pipe or fish below the jar.
Description
EASA,031 l~cn~
This in~ention relates to well jars generally and in particular to mechanical jars that employ a spring operated mechanism in their operation.
Well jars are incorporated in the downhole assembly of a drill string. They are us~ually located just above the drill collars, since it is usually the drill collars that become stuck in the hole. If the jars are used in a fishing string, they arP generally located just above the fishing tool. Their purpose i8 to strike a sharp blow on the stuck drill collars, fish or ~he like, ~enaing to move it up or down and free i~ from whatever is holding it in the well bore, such as differential pressure, wall cake, and the like. The energy imparted to the fish ~y the jar is obtained from the drill pipe above it that acts as a long spring that is either compressed or stretched and then suddenly released to transmit the energy stored in the stretched or compressed drill pipe to the fish. These large amounts of energy, transmit~ed quickly to the fish in this ; 20 matter, will tend to jar the fish free of whatever is holding it. "Fish" as used herein is meant to include not only the conventional fish, which is usually a portion of the drill string that has been left in the hole, but also 3331~
This in~ention relates to well jars generally and in particular to mechanical jars that employ a spring operated mechanism in their operation.
Well jars are incorporated in the downhole assembly of a drill string. They are us~ually located just above the drill collars, since it is usually the drill collars that become stuck in the hole. If the jars are used in a fishing string, they arP generally located just above the fishing tool. Their purpose i8 to strike a sharp blow on the stuck drill collars, fish or ~he like, ~enaing to move it up or down and free i~ from whatever is holding it in the well bore, such as differential pressure, wall cake, and the like. The energy imparted to the fish ~y the jar is obtained from the drill pipe above it that acts as a long spring that is either compressed or stretched and then suddenly released to transmit the energy stored in the stretched or compressed drill pipe to the fish. These large amounts of energy, transmit~ed quickly to the fish in this ; 20 matter, will tend to jar the fish free of whatever is holding it. "Fish" as used herein is meant to include not only the conventional fish, which is usually a portion of the drill string that has been left in the hole, but also 3331~
- 2 -stucX drill collars that are a part o~ the downhole drilling assembly.
The jars of this invention operate on the principle described in U.S. Patent No. 3,208,541 ,and U.S. Patent No.
The jars of this invention operate on the principle described in U.S. Patent No. 3,208,541 ,and U.S. Patent No.
3,233,690. Basically, the jars descri~ed in the pa~ents and the jar of this invention include two telescoping members, an inner member and an outer member. In the jars described in the patents, the inner member was provided with a plurality of notches that had curved outwardly flaring 10 sidewalls and a longitudinally extendi~g grooveO A
plurality of rollers were mounted on the inside of the outer member for moving into and out of the notches and the groove. When the rollers were in the notches, the `two telescoping members could not move longitudinally rela~ive ; to each other~ When the rollers were in the groove, the two members could move longitudinally relative to each other.
Their movement longitudinally was limited by shoulders and .
it was through the shoulders that the energy stored in the drill pipe above during the operation of the jar was transmitted to the stuck fish.
In order to build up energy in the drill pipe, the rollers were held in the grooves by a spring. When the longitudinal force on the jars had a horizontal component due to the flared sidewalls of the notches that are large enough to rotate the ~wo members relative to each other and . force the rollers out of the groove, the jar would trip and the t~o members would move relative ~o each other with great velocity until they should meet. The impact of the engaging ~2~
shoulders would produce a sharp blow on the fish. The amount of energy transmitted to the fish depended upon the spring force resisting the lateral movement of the rollers ; and the angle that the sides of the notches made with the horizont~l, which de~ermined the horizontal component produced by a given longi~udinal force.
This arrangement has several drawbacks. With the rollers mounted on the inside of the outer member, it is practically impossible to chec~ the condition of the rollers 10 to determine, for example, if they were still rolling and whether or not they were cracked or even broken off.
Usual~y the rollers were mountcd on a shaft that extended into a hole in the side of the outer member. The shaft was welded to the outer member to hold the roller in position.
The heat of the weld often caused the shaft to warp and cant the axis of rotation of the roller so that the roller did not rota~e in a plane parallel to the vertical plane of the tool. This, in ~urn, would create undue stress concentrations on the roller and on the notch on the inner 20 member resulting in galling of the metal surfaces and premature failure of the jars. In addition, as mentioned above, since the rollers were welded in place on the inside of the outer member, when one or more of the rollers were damaged beyond repair, the entire outer member would have to be replaced.
Thus broadly, the invention pertains to a mechanical well jar having inner and outer tubular members movable longitudinally relative to each other a limited distance, means for connecting one of the members to a pipe string - 3a -~2~Çi6 extending above the jar, and means for connecting the o-ther member to the pipe string below -the jar, with annular shoulders on the members that engage to limit the relative longi-tudinal movement of the members. The improvement comprises a plurality of laterally spaced, arcuate cam plates each removably attached to tile inner surface of the outer member, with each of the plates having a laterally extending U-shaped notch opening into the space between the plates and formed with curved outwardly flaring sidewalls. Means removably mounted on the outer surface of the inner member extend into the spaces between the cam plates for movement into the U-shaped notches to hold the members Erom longitud-inal movement relative to each otherO Resilient means urge the members to rotate in the direction to move the holding means into the notches and allow the holding means to move out of the notches when a longitudinal force is imposed on the jar sufficient for the flared sidewalls of the notches to provide a lateral component of force on the holding means to overcome the force of the resilient means sufficient to move the holding means out of the notches.
Thus, the tubular members move longitudinally relative to each other and move the annular shoulders together sharply.
More particularly, this invention seeks to provide a mechanical jar of the type described above ln which the rollers are mounted on the inner member and the notches are provided on the inner surface of the outer member and no welding is required to assemble the jar.
1233~6 Wi.th the rollers mounted on the outside oE the inner member thei.r condition can be easily checked and the rollers are mounted in such a manner that any damaged rollers can be quickly replaced.
Preferably, U-shaped grooves are located in cam plates that are attached inside the outer member by threaded members that can be removed from the outside thereby allowlng the cam plates to be removed, inspected, replaced or repaired easily and conveniently thereby greatly simplifying the maintenance required to keep the jars in good operating conditions.
These and other aspects, 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.
~L~33~
In the Drawings Figure 1 is a vertical, sectional view through the preferred embodiment of the well jar of this invention.
Figure 2 is a sectional view taken along line 2--2 of Figure l.
Figure 3 is a sectional view taken along line 3--3 of Figu~e 1.
Figure 4 is a vertical, sectional view on an enlarged scale of the portion of the jar in Figure 1 where the cam pl~tes and rollers are located.
Figure 5 is a view taken along line 5--5 of Figure 4.
Figure 6 is a cross-sectional view through one of the roller assemblies attached to the inner member of the jar.
The jar includes outer member 10 and inner memher 11 that are movable longitudinally relative to each other a limited distance. In Figure 1, these tubular members are shown in one piece whereas they are actually made up of a number of tubular sections connected together by threads for ease of assembly and machining, and for ease of repair or replacement of worn or broken parts of the jar. Inner tubular member 11 is provided with appropriate threads (not shown) for connecting the inner member to the drill string e~tending between the jar and the surface. Outer member 10 has threads 12 on its lower end for connecting the outer tubular member to the fishing tool or the portion of the drill string e~tending beLow the jar. T~lis is the usual 2~3~
~j arrangement. The roles of the two ~embers could be reversed, if desired.
The distance the members can move longitudinally - relative to each other is limited by annlllar shoulders on the member~. When the jar is in use, the outer tubular member will be connected to the stuck pipe and therefore will not be doing any moving unless the jar can knock the fish loose from its stuck position in the well bore.
Therefore, it is the inner member that moves relative to the 10 outer mem~er during a jarring operation. As the inner member moves downwardly, its travel is limited by the engagement of downwardly facing shaulder 14 on the inner _- member and upwardly facing shoulder 16 on ~he auter member.
~Upward mo~ement is limited by downwardly facing shoulder 18 on the outer member and upwardly facing shoulder 20 on the inner member. In operation, as explained above, these shoulders come together with grea~ force due to the energy stored in the drill pipe above the jar before the jar is tripped.
In this embodiment, the jar can jar ~p or it can jar down or both. Holding means are provided to hold the two members from relative movement while energy is being stored in the drill string. In the embodiment shown, the holding means includes three cam plates 22, 24, and 26 that are laterally spaced around the inner surface of the outer member. As shown in Figures 2 and 3, they are arcuate in cross-section to fit the curvature of the inner surface.
The cam plates are held in position by a plurality of cap screw5 2a that extend through openings provided in the wall ~233~
, of the outer member to engage tappecl holes in the cam plates. To position the cam plates to receive the cap screws, locator pins 30, are positioned in openings in the sidewall of outer member 10 to engage a non-tapped locating hole at the upper end of each cam plate. These pins align the tapped holes in the plates wi~h the openings in the siaewall of the outer member to insure that the cam plates are properly positioned relative to each other on ths inside wall of the outer member. These locator pins are shown in Figure 2.
Each cam plate has a plurality of U-shaped notches as best seen in Figure 4 where the inner member i5 broken away to show cam plate 22 in elevation. In this embodiment, two longitudinally spaced sets of three notches each are used~
The upper set is made up of notches 32, 34, and 36. The lower set i5 made up of notches 38, 40, and 42. The notches open outwardly in a Iateral direction with diverging curved sidewall~.
A plurality of rollers are located on the outer surface of the inner member to engage the notches and hold the inner member from longitudinal movement relative to the outer member. When the rollers are out of engagement with the notches and positioned in the longitudinally extending spaces be~ween the cam plates, as shown in Figure 5f where rollers 44, 46, and 48 are positioned in between cam plates 22, 24, and 26, the inner member can move longitudinally relative to the outer member. The rollers are attached to the outer sur~ace o~ inner member in equally sp~ced rolls in 33~
I ~ - 8 -¦ groups of three. They are spaced vertically as shown in Figure 4 so each roller can engage one of the notches on the cam plates.
A typical roller assembly is shown in Figure 6. It in~ludes shaft 50 and cap,screw 52 that attaches the roller assembly to innex member 11. Shaft 50 has cylindrical surface 54 upon which roller 56 is mounted for rotation relative to shaft 50. To assemble the roller on the shaft, cylindrical surface 54 extends outwardly to the end of the shaft. The roller is moved into position over the cylindri-cal surface and then the end of,.the shaft is upset to form retaining ring 58 to hold 'the roller on the shaft while allowing the roller to freely rotate relative to the shaft.
In order to relieve cap screw 52 of much of the ~tress imposed on shaft 50 by roller 56, the inner end of shaft 50 is cup~shaped to provide annular section 60 tha~ extends intQ annular recess 62 in the sidewall of inner member 11.
By designing annular section 60 of the shaft so th~t there is little clearance between the walls of'the annular section and the walls of the recess, the reaction forces required to resist the load imposed on the shaft by the roller are transmitted directly ~o the inner member through annular section 60.
To hold the rollers in engagement with the notches, two torsion springs 64 and 66 are positioned at the lower end of -, the jar. The upper end of each spring is connected to the inner member through pins 68 and 70. These pins engage keyways 72 and 74 that extend along the outer surface of the - 9 - ~233~
inner member so that the spring can exert a torque on the inner member but still allow relative movement of the inner member relative to the springs. ~he lower end of each ~¦ spring is connected to the outer member through pins 76 and 78~ ~
Torque is imposed on the inner member by rotating the inner member relati~e to the outer mernber a desired distance and then inserting the pins. The torque constant:ly urges the inner member to rotate in a direction to move ~he rollers into the notches. The amoun~ of torque imposed on the inner member determines at what upward or downwaxd force the jar will trip. Also ent-ëring into the de~ermination of when the jar will trip is the angle of the top and bottom sides of the notches. They do not have to be the same. The notches could be arranged to trip at a lesser force on a down-jar then on an up jar, if desired.
As pointed out a~ove, one of the advantages and fea-~ures of this invention is that the inner member and the rollers can be quickly and easily removed from the outer member to allow inspection of the rollers for damage and wear. Any broken or worn rollers can be quickly and easily replaced. The cam plates can be quickly and easil.y removed for inspection and replacement simply by re~oving the locator pins and cap screws.
plurality of rollers were mounted on the inside of the outer member for moving into and out of the notches and the groove. When the rollers were in the notches, the `two telescoping members could not move longitudinally rela~ive ; to each other~ When the rollers were in the groove, the two members could move longitudinally relative to each other.
Their movement longitudinally was limited by shoulders and .
it was through the shoulders that the energy stored in the drill pipe above during the operation of the jar was transmitted to the stuck fish.
In order to build up energy in the drill pipe, the rollers were held in the grooves by a spring. When the longitudinal force on the jars had a horizontal component due to the flared sidewalls of the notches that are large enough to rotate the ~wo members relative to each other and . force the rollers out of the groove, the jar would trip and the t~o members would move relative ~o each other with great velocity until they should meet. The impact of the engaging ~2~
shoulders would produce a sharp blow on the fish. The amount of energy transmitted to the fish depended upon the spring force resisting the lateral movement of the rollers ; and the angle that the sides of the notches made with the horizont~l, which de~ermined the horizontal component produced by a given longi~udinal force.
This arrangement has several drawbacks. With the rollers mounted on the inside of the outer member, it is practically impossible to chec~ the condition of the rollers 10 to determine, for example, if they were still rolling and whether or not they were cracked or even broken off.
Usual~y the rollers were mountcd on a shaft that extended into a hole in the side of the outer member. The shaft was welded to the outer member to hold the roller in position.
The heat of the weld often caused the shaft to warp and cant the axis of rotation of the roller so that the roller did not rota~e in a plane parallel to the vertical plane of the tool. This, in ~urn, would create undue stress concentrations on the roller and on the notch on the inner 20 member resulting in galling of the metal surfaces and premature failure of the jars. In addition, as mentioned above, since the rollers were welded in place on the inside of the outer member, when one or more of the rollers were damaged beyond repair, the entire outer member would have to be replaced.
Thus broadly, the invention pertains to a mechanical well jar having inner and outer tubular members movable longitudinally relative to each other a limited distance, means for connecting one of the members to a pipe string - 3a -~2~Çi6 extending above the jar, and means for connecting the o-ther member to the pipe string below -the jar, with annular shoulders on the members that engage to limit the relative longi-tudinal movement of the members. The improvement comprises a plurality of laterally spaced, arcuate cam plates each removably attached to tile inner surface of the outer member, with each of the plates having a laterally extending U-shaped notch opening into the space between the plates and formed with curved outwardly flaring sidewalls. Means removably mounted on the outer surface of the inner member extend into the spaces between the cam plates for movement into the U-shaped notches to hold the members Erom longitud-inal movement relative to each otherO Resilient means urge the members to rotate in the direction to move the holding means into the notches and allow the holding means to move out of the notches when a longitudinal force is imposed on the jar sufficient for the flared sidewalls of the notches to provide a lateral component of force on the holding means to overcome the force of the resilient means sufficient to move the holding means out of the notches.
Thus, the tubular members move longitudinally relative to each other and move the annular shoulders together sharply.
More particularly, this invention seeks to provide a mechanical jar of the type described above ln which the rollers are mounted on the inner member and the notches are provided on the inner surface of the outer member and no welding is required to assemble the jar.
1233~6 Wi.th the rollers mounted on the outside oE the inner member thei.r condition can be easily checked and the rollers are mounted in such a manner that any damaged rollers can be quickly replaced.
Preferably, U-shaped grooves are located in cam plates that are attached inside the outer member by threaded members that can be removed from the outside thereby allowlng the cam plates to be removed, inspected, replaced or repaired easily and conveniently thereby greatly simplifying the maintenance required to keep the jars in good operating conditions.
These and other aspects, 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.
~L~33~
In the Drawings Figure 1 is a vertical, sectional view through the preferred embodiment of the well jar of this invention.
Figure 2 is a sectional view taken along line 2--2 of Figure l.
Figure 3 is a sectional view taken along line 3--3 of Figu~e 1.
Figure 4 is a vertical, sectional view on an enlarged scale of the portion of the jar in Figure 1 where the cam pl~tes and rollers are located.
Figure 5 is a view taken along line 5--5 of Figure 4.
Figure 6 is a cross-sectional view through one of the roller assemblies attached to the inner member of the jar.
The jar includes outer member 10 and inner memher 11 that are movable longitudinally relative to each other a limited distance. In Figure 1, these tubular members are shown in one piece whereas they are actually made up of a number of tubular sections connected together by threads for ease of assembly and machining, and for ease of repair or replacement of worn or broken parts of the jar. Inner tubular member 11 is provided with appropriate threads (not shown) for connecting the inner member to the drill string e~tending between the jar and the surface. Outer member 10 has threads 12 on its lower end for connecting the outer tubular member to the fishing tool or the portion of the drill string e~tending beLow the jar. T~lis is the usual 2~3~
~j arrangement. The roles of the two ~embers could be reversed, if desired.
The distance the members can move longitudinally - relative to each other is limited by annlllar shoulders on the member~. When the jar is in use, the outer tubular member will be connected to the stuck pipe and therefore will not be doing any moving unless the jar can knock the fish loose from its stuck position in the well bore.
Therefore, it is the inner member that moves relative to the 10 outer mem~er during a jarring operation. As the inner member moves downwardly, its travel is limited by the engagement of downwardly facing shaulder 14 on the inner _- member and upwardly facing shoulder 16 on ~he auter member.
~Upward mo~ement is limited by downwardly facing shoulder 18 on the outer member and upwardly facing shoulder 20 on the inner member. In operation, as explained above, these shoulders come together with grea~ force due to the energy stored in the drill pipe above the jar before the jar is tripped.
In this embodiment, the jar can jar ~p or it can jar down or both. Holding means are provided to hold the two members from relative movement while energy is being stored in the drill string. In the embodiment shown, the holding means includes three cam plates 22, 24, and 26 that are laterally spaced around the inner surface of the outer member. As shown in Figures 2 and 3, they are arcuate in cross-section to fit the curvature of the inner surface.
The cam plates are held in position by a plurality of cap screw5 2a that extend through openings provided in the wall ~233~
, of the outer member to engage tappecl holes in the cam plates. To position the cam plates to receive the cap screws, locator pins 30, are positioned in openings in the sidewall of outer member 10 to engage a non-tapped locating hole at the upper end of each cam plate. These pins align the tapped holes in the plates wi~h the openings in the siaewall of the outer member to insure that the cam plates are properly positioned relative to each other on ths inside wall of the outer member. These locator pins are shown in Figure 2.
Each cam plate has a plurality of U-shaped notches as best seen in Figure 4 where the inner member i5 broken away to show cam plate 22 in elevation. In this embodiment, two longitudinally spaced sets of three notches each are used~
The upper set is made up of notches 32, 34, and 36. The lower set i5 made up of notches 38, 40, and 42. The notches open outwardly in a Iateral direction with diverging curved sidewall~.
A plurality of rollers are located on the outer surface of the inner member to engage the notches and hold the inner member from longitudinal movement relative to the outer member. When the rollers are out of engagement with the notches and positioned in the longitudinally extending spaces be~ween the cam plates, as shown in Figure 5f where rollers 44, 46, and 48 are positioned in between cam plates 22, 24, and 26, the inner member can move longitudinally relative to the outer member. The rollers are attached to the outer sur~ace o~ inner member in equally sp~ced rolls in 33~
I ~ - 8 -¦ groups of three. They are spaced vertically as shown in Figure 4 so each roller can engage one of the notches on the cam plates.
A typical roller assembly is shown in Figure 6. It in~ludes shaft 50 and cap,screw 52 that attaches the roller assembly to innex member 11. Shaft 50 has cylindrical surface 54 upon which roller 56 is mounted for rotation relative to shaft 50. To assemble the roller on the shaft, cylindrical surface 54 extends outwardly to the end of the shaft. The roller is moved into position over the cylindri-cal surface and then the end of,.the shaft is upset to form retaining ring 58 to hold 'the roller on the shaft while allowing the roller to freely rotate relative to the shaft.
In order to relieve cap screw 52 of much of the ~tress imposed on shaft 50 by roller 56, the inner end of shaft 50 is cup~shaped to provide annular section 60 tha~ extends intQ annular recess 62 in the sidewall of inner member 11.
By designing annular section 60 of the shaft so th~t there is little clearance between the walls of'the annular section and the walls of the recess, the reaction forces required to resist the load imposed on the shaft by the roller are transmitted directly ~o the inner member through annular section 60.
To hold the rollers in engagement with the notches, two torsion springs 64 and 66 are positioned at the lower end of -, the jar. The upper end of each spring is connected to the inner member through pins 68 and 70. These pins engage keyways 72 and 74 that extend along the outer surface of the - 9 - ~233~
inner member so that the spring can exert a torque on the inner member but still allow relative movement of the inner member relative to the springs. ~he lower end of each ~¦ spring is connected to the outer member through pins 76 and 78~ ~
Torque is imposed on the inner member by rotating the inner member relati~e to the outer mernber a desired distance and then inserting the pins. The torque constant:ly urges the inner member to rotate in a direction to move ~he rollers into the notches. The amoun~ of torque imposed on the inner member determines at what upward or downwaxd force the jar will trip. Also ent-ëring into the de~ermination of when the jar will trip is the angle of the top and bottom sides of the notches. They do not have to be the same. The notches could be arranged to trip at a lesser force on a down-jar then on an up jar, if desired.
As pointed out a~ove, one of the advantages and fea-~ures of this invention is that the inner member and the rollers can be quickly and easily removed from the outer member to allow inspection of the rollers for damage and wear. Any broken or worn rollers can be quickly and easily replaced. The cam plates can be quickly and easil.y removed for inspection and replacement simply by re~oving the locator pins and cap screws.
Claims (4)
1. In a mechanical well jar having inner and outer tubular members movable longitudinally relative to each other a limited distance, means for connecting one of the members to a pipe string extending above the jar, means for connecting the other member to the pipe string below the jar, annular shoulders on the members that engage to limit the relative longitudinal movement of the members, the improvement comprising a plurality of laterally spaced, arcuate cam plates each removably attached to the inner surface of the outer member, each of said plates having a laterally extending U-shaped notch opening into the space between the plates and formed with curved outwardly flaring sidewalls, means removably mounted on the outer surface of the inner member to extend into the spaces between the cam plates for movement into the U-shaped notches to hold the members from longitudinal movement relative to each other, and resilient means urging the members to rotate in the direction to move the holding means into the notches and allow the holding means to move out of the notches when a longitudinal force is imposed on the jar sufficient for the flared sidewalls of the notches to provide a lateral component of force on the holding means to overcome the force of the resilient means that is sufficient to move the holding means out of the notches allowing the tubular members to move longitu-dinally relative to each other and move the annular shoulders together sharply.
2. The jar of claim 1 in which the holding means comprises a plurality of roller assemblies, each assembly including a shaft member and a roller mounted on the shaft for rotation relative to the shaft, and means for attaching the assembly to the outer surface of the inner member.
3. The jar of claim 2 in which the outer surface of the inner member has a plurality of annular recesses and the inner ends of the shafts of the roller assemblies are annular in cross-section and extend into the annular recess-es when the roller assemblies are attached to the inner member to transmit to the inner member a portion of the bending force imposed on the roller assemblies when the roller assemblies are in engagement with the U-shaped notches.
4. The jar of claim 1, 2 or 3 in which the cam plates are attached to the inside of the outer member by threaded members that extend through the wall of the outer member and that can be removed from outside the outer member to allow the cam plates to be removed and repaired or replaced.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/696,997 US4665998A (en) | 1985-01-31 | 1985-01-31 | Mechanical well jar |
| US06/696,997 | 1985-01-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1233166A true CA1233166A (en) | 1988-02-23 |
Family
ID=24799369
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000485835A Expired CA1233166A (en) | 1985-01-31 | 1985-06-28 | Mechanical well jar |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US4665998A (en) |
| CA (1) | CA1233166A (en) |
| GB (1) | GB2170532B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5669458A (en) * | 1996-03-01 | 1997-09-23 | Anders; Edward O. | Rotary jar |
| US5875842A (en) * | 1996-03-05 | 1999-03-02 | Wyatt; Wilfred B. | Multi-impact jarring apparatus and method for using same |
| US5857710A (en) * | 1996-11-04 | 1999-01-12 | Schlumberger Technology Corporation | Multi-cycle releasable connection |
| US6745836B2 (en) * | 2002-05-08 | 2004-06-08 | Jeff L. Taylor | Down hole motor assembly and associated method for providing radial energy |
| US7111678B2 (en) * | 2003-10-30 | 2006-09-26 | Impact Selector, Inc. | Field adjustable impact jar |
| EP2929124B1 (en) | 2013-06-26 | 2022-12-28 | Impact Selector International, LLC | Downhole-adjusting impact apparatus and methods |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3200895A (en) * | 1963-11-06 | 1965-08-17 | Drilling Jars Inc | Jar mechanism |
| US3233690A (en) * | 1964-09-02 | 1966-02-08 | Richard R Lawrence | Flexible well jar |
| US3431990A (en) * | 1967-02-02 | 1969-03-11 | Houston Eng Inc | Keyseat wiper |
| US4023630A (en) * | 1976-01-14 | 1977-05-17 | Smith International, Inc. | Well jar having a time delay section |
| US4394883A (en) * | 1980-11-03 | 1983-07-26 | Dailey Oil Tools, Inc. | Well jar |
| US4408670A (en) * | 1981-04-24 | 1983-10-11 | Schoeffler William N | Impact cam subassembly for drills |
-
1985
- 1985-01-31 US US06/696,997 patent/US4665998A/en not_active Expired - Fee Related
- 1985-06-28 CA CA000485835A patent/CA1233166A/en not_active Expired
- 1985-07-26 GB GB08518893A patent/GB2170532B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB8518893D0 (en) | 1985-09-04 |
| US4665998A (en) | 1987-05-19 |
| GB2170532B (en) | 1988-04-07 |
| GB2170532A (en) | 1986-08-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |