CA2058703A1 - Latch mechanism for use in association with a mechanical drilling jar - Google Patents
Latch mechanism for use in association with a mechanical drilling jarInfo
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- CA2058703A1 CA2058703A1 CA 2058703 CA2058703A CA2058703A1 CA 2058703 A1 CA2058703 A1 CA 2058703A1 CA 2058703 CA2058703 CA 2058703 CA 2058703 A CA2058703 A CA 2058703A CA 2058703 A1 CA2058703 A1 CA 2058703A1
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- mandrel
- housing
- latch
- split collet
- inclined faces
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Abstract
UNITED STATES/CANADA
Latch Mechanism for use in Association with a Mechanical Drilling Jar Donald H. Lineham ABSTRACT OF THE DISCLOSURE
A latch mechanism for a mechanical drilling jar has a first latch ring having inclined grooves, a second latch ring also having inclined grooves, a split collet disposed between the first and second latch rings, first and second sets of roller bearings disposed in the inclined grooves between the first latch ring and the split collet and between the second latch ring and the split collet respectively, and a set of Belville springs to maintain pressure on the split collet. The inclined grooves convert the axial compressional force imparted by the Belville springs into inwardly directed radial forces.
Latch Mechanism for use in Association with a Mechanical Drilling Jar Donald H. Lineham ABSTRACT OF THE DISCLOSURE
A latch mechanism for a mechanical drilling jar has a first latch ring having inclined grooves, a second latch ring also having inclined grooves, a split collet disposed between the first and second latch rings, first and second sets of roller bearings disposed in the inclined grooves between the first latch ring and the split collet and between the second latch ring and the split collet respectively, and a set of Belville springs to maintain pressure on the split collet. The inclined grooves convert the axial compressional force imparted by the Belville springs into inwardly directed radial forces.
Description
FIELD OF T}I13 INVEI~TION
This invention relates to an improved latch mechanism or use in association with mechanical drilling jars used in oil and gas well drilling activities to dislodge drill pipe or other drilling tools and objects that have become lodged or stuck in the well bore.
BACKGROUND A~D SUMMA~Y ~F T~E INVENTION
Mechanical drilling jars are telescoping devices that form part of a drill pipe string. A
mechanical drilling jar is formed from an upper tubular member (housing) that threads onto one part of the drill string and a lower tubular member (mandrel) that telescopes inside the housing and threads onto an other part of the drill string. The mandrel and housing include complementary splined sections that prevent relative rotational movement of the mandrel and housing.
The purpose of mechanical drilling jar is to dislodge stuck pipe or drill tools from the well bore.
It works by impact, and for that purpose the mechanical drilling jar is designed to apply a controlled impact force to the lower end of the drill string. The impact may be applied in the up hole ; 30 direction (upon movement of the jar upward) or the down hole direction (upon movement of the jar downward).
It is known to provide such a mechanical drilling jar as described in Canadian patent no.
l,221,960 issued May 19, 1987, to Oil Patch Group Inc.
A copy of Figure 1 of the patent is shown here as Figure 1 in this patent document for ease of reference. In that patent there is described a ,~J ~,IJ ~ S .
mechanical drilling jar in which the uphole and downhole impact forces are transmitted across respective pairs of impact surfaces (35, 37 and 39, 40)r one impact surface of each pair being on the housing and one on the mandrel. The housing is composed of splined housing 2, latch housing 3 and top sub 4 each threaded together with threaded sections 27, 28, 29 and 30 and sealed with seals 32. The housing terminates in threaded section 31 for engagement with the next higher part of the drill string. The mandrel is formed in two parts, a splined -mandrel 1 and a knocker mandrel 5 which are threaded together with threaded sections 20 and 21 and sealed with seal 22, and terminates in a threaded end 23 for engagement with the next lower part of the drill string. The mandrel has splines 33 that engage with splines 36 of the housing. The knocker mandrel 5 has an upper end 24 that threads onto an oversize safety nut 25.
The housing and mandrel are connected and disconnected to each other by a latch assembly including a first latch ring 7, a second latch ring 8 and a split collet 6 disposed between the first and second latch rings. The split collet 6 has pyramidal teeth 14 on its interior surface that are engageable and disengageable with pyramidal teeth 15 on the outer surface of the mandrel. The mandrel and housing are sealed together by seals 12. The first latch ring 7 abuts against a shoulder 13 on the housing and the second latch ring 8 abuts against a plurality of Belville springs 11 which in turn abut against a shoulder 42 of the housing. The latch rings are connected to the split collet through latch pins 9A
and 9~ and it is to this connection mechanism between the latch rings and the split collet that the present invention is directed. The latch pins 9A and 9B
translate axial compression forces from the Belville springs into radially inwardly directed forces that tend to keep the split collet engaged with the mandrel.
In operation, the drilling jar described in Canadian patent no. 1,221,960 works as follows.
Firstly will be described the upward jar. An upward force is applied to the drill string by pulling on the upper end of the drill string. Upward forces are transmitted across the shoulder 13 through the first latch ring 7, latch pin 9A and the split collet 6 to the knocker mandrel 5. The angles of the faces of the teeth on the mandrel and the teeth on the split collet tend to translate the upward force into a radially outwardly directed force. When a preset level of the upward force is reached, that is when the outward force overcomes the inward force from the Belville springs, the split collet 6 moves outward, disengaging from the knocker mandrel 5, and the housing moves upward until the surfaces 39 and 40 impact each other and transmit a jarring force to the knocker mandrel.
For the downward jar, compressional force is imposed on the housing and is transmitted through shoulder 42, Belville springs 11, latch ring 8, latch pin 9B and split collet 6 to knocker mandrel 5. Again, the inclined faces of the teeth on the mandrel and on the split collet tend to translate this compressional force into a radially outwardly directed force. At a preset level of compression, the outward forces on the split collet overcome the inward forces and the split collet 6 moves outward, disengaging from the mandrel 5. The freed housing then moves downward until impact . f, i ~ I f ~ ~ ~
surfaces 35 and 37 meet transmitting a downward jarring force downhole through the splined mandrel 1.
If any of the joints fail, safety nut 25 is designed to engage shoulder 43 on the top sub 4 and prevent 5disengagement of the mandrel and the housing.
The preset tension and compression at which the split collet 6 disengages from the knocker mandrel 5 is adjustable in part by the force exerted by the Belville springs. The ratio of the downward to the 10upward jarring force is adjustable by the length of the latch pins. Incorrect adjustment of the latch pins can result in the failure of the collet to disengage or its premature disengagement. The latch pins are also easily broken since strong forces are transmitted 15by them.
~; The inventor has found that omission of the latch pins and use of opposed inclined faces results in considerable wear of the faces, and considerably greater pull required for the trigger level to be 20reached. Also, when the jar is fired (the split collet ;~ disengages from the mandrel), the split collet comes out at high speed and impacts heavily against the ` housing. Therefore, the use of opposed inclined faces is not recommended.
25There is therefore proposed an improvement to the mechanical drilling jar proposed in Canadian patent no. 1,221,960 in which the latch pins are replaced by roller bearings placed in inclined slots formed between the latch rings and split collet.
:
BRIEF DESCRIPTION OF THE DRAWINGS
There will now be described a preferred embodiment of the invention, with reference to the drawings, by way of illustration, in which like numerals denote like elements and in which:
Figure 1 is a longitudinal section of a prior art mechanical drilling jar;
Figure 2 is a longitudinal section of a latching mechanism according to the invention showing the latching mechanism engaged;
Figure 3 is a longitudinal section of a latching mechanism according to the invention showing the latching mechanism disengaged;
Figure 4 is a cross-section along the line 4-4 of Figure 2;
Eigure 5 is a cross-section along the line 5-5 of Figure 3; and Figure 6 shows a detailed section of a roller bearing for use with the invention.
DET~ILED DESCRIPTION ~F PREFERRÆD EMBODIMENTS
As noted and discussed above in the background section of this patent document, Figure 1 shows the prior art mechanical drilling jar. Figures 2l 3, 4 and 5 show the working of an improvement of that drilling jarl and the same numerals have been retained in those Figures to identify elements that have a common function and design. The design and function of common elements are therefore not described here, since they are set out above in the background and summary of the invention.
While the mandrel and housing are shown in two sections and three sections respectively, each threaded and sealed together, each of the mandrel and ~ J~
housing forms a unitary part that moves axially as a unit. Therefore in this detailed description and in the claims it will be understood that when the mandrel is referred to it means the combined splined and knocker mandrel and when the housing is referred to it means the combined splined housing, latch housing and top sub.
Referring to Figures 2, 3, 4 and 5, there is shown a mandrel 45 (the part shown is the knocker mandrel) and housing 46 (shown are the latch housing and the top sub). Disposed between first shoulder 13 and second shoulder 42 is a latch mechanism comprising, in order, a first latch ring 7, a plurality of first roller bearings 19, a split collet 6, a plurality of second roller bearings l9A, a second latch ring 8, and a plurality of Belville springs 11.
The components of the latch mechanism are longer than the distance between the shoulders 13 and 42, which compresses the Belville springs to place a preset compression on the latch mechanism that can be adjusted by choosing the number of Belville springs or by adding or removing spacers. The Belville springs form spring means disposed between the second latch ring and the second shoulder on the housing. While such springs are preferred, they may be replaced by other spring means.
The first roller bearings 19 roll on first inclined faces 51 machined into the first latch ring 7 to form grooves disposed circum~erentially about the first latch ring. The first roller bearings 19 also roll on second inclined faces 52 machined into one end of the split collet 6 to form a second set of grooves disposed circumferentially about the split collet. The inclined faces 51 and 52 are complementary to each other and during assembly are placed opposite each other with a roller bearing in each groove.
The second roller bearings l9A roll on third inclined faces 53 machined into one end of the split collet 6 to form a third set of grooves disposed circumferentially about the split collet. The second roller bearings l9A roll on fourth inclined faces 54 machined into the second latch ring 8 to form a fourth set of grooves disposed circumferentially about the second latch ring. The grooves 53 and 54 are also complementary to each other as with the grooves 51 and 52.
The roller bearings are best shown in Figure 6 which is exemplary of each of the grooves. The groove terminates in a flange 55 which prevents the roller bearing from rolling out of the groove. The faces 51, 52, 53 and 54 are inclined in a manner so that axial forces across the faces tend to move the ; split collet 6 radially inward towards the mandrel. It ; 20 is these forces that tend to maintain the split collet 6 engaged with the mandrel 45 as shown in Figures 2 and 4.
The operation of the latch mechanism is as follows. For a downward jar, the housing is urged downward (placed in compression) and the downward forces are transmitted through shoulder 42, Belville springs 11, second latch ring 8, second roller bearings l9A and pyramidal teeth 14, 15 to the mandrel 45 as shown in Figures 2 and 4. At a preset force, the outward force exerted by the inclined faces of the pyramidal teeth on the split collet 6 overcomes the radially inward directed force across the second roller bearings and forces the split collet 6 rapidly outward, leaving the mandrel 45 and housing 46 disengaged and free to move axially as shown in Figures 3 and 5. The downward force on the housing 46 will urge it downward relative to the mandrel and the impact surfaces 35, 37 (Figure 1) will engage and transmit a jarring force downhole. By pulling up on the housing, the latch mechanism can be returned to the original position with pyramidal teeth engaged.
For an upward jar, the housing is urged upward (placed in tension) and the upward forces are transmitted through the shoulder 13, first latch ring 7, first roller bearings 19 and split collet 6 to mandrel 45. The inclined faces of the pyramidal teeth will tend to urge the split collet 6 outward, and at a preset force, the outward force exerted through the inclined faces of the pyramidal teeth will overcome the force exerted by the Belville springs and the roller bearings on the split collet 6. The split collet 6 will then move rapidly outward and the housing 46 will move upward relative to the mandrel 45 until the i~pact surfaces 39 and 40 (Figure 1) meet and transmit a jarring force into the mandrel.
The force required to disengage the split collet 6 depends on several factors such as (1) the angle and smoothness of the faces on the pyramidal teeth (preferably about 45), (2) the angle of the inclined faces 51, 52, 53 and 54 (which is preferably at an angle of 30 to a radius of the tool) and (3) the force applied by the Belville springs.
The forces transmitted through the second roller bearings 19A primarily holds the split collet 6 against the mandrel 45 when the jarring tool is operated for a downward jar (housing under compression). By comparison, forces transmitted through both sets of roller bearings l9,19A hold the s~
split collet 6 against the mandrel 45 when the jarring tool is operated for an upward jar. Consequently, the force required to dislodge the split collet 6 for a downward jar will be less than the force required to dislodge the split collet 6 for an upward jar. The desired predetermined tension or compression at which the split collet 6 disengages may be set by adjustment of the number of Belville springs and changing the angle of the inclined faces 51, 52, 53 and 54.
Generally, the less the angle of the inclined faces, the lower the force required to dislodge the split collet 6.
The split collet is preferably made of ASTRALOYtm, and the mandrel in the area of the pyramidal teeth is preferably induction hardened. The joints between the housing components are preferably stress relieved. In a 6" tool, the roller bearings are preferably about 1~" long.
A person skilled in the art could make immaterial modifications to the invention described and claimed in this patent without departing from the essence of the invention.
For example, the lower latch ring could conceivably be omitted, and -the grooves placed on the housing, but since the grooves have to be milled, this is very difficult to make. The grooves could also be made arcuate, so that they begin at an incline of about 35 and change gradually to an incline of about 25, so that the inclination decreases with increasing distance from the center of the tool. This would result in a slightly higher level of compression or tension at which the split collet will disengage from the mandrel, but would mean that the disengagement would be progressively faster.
This invention relates to an improved latch mechanism or use in association with mechanical drilling jars used in oil and gas well drilling activities to dislodge drill pipe or other drilling tools and objects that have become lodged or stuck in the well bore.
BACKGROUND A~D SUMMA~Y ~F T~E INVENTION
Mechanical drilling jars are telescoping devices that form part of a drill pipe string. A
mechanical drilling jar is formed from an upper tubular member (housing) that threads onto one part of the drill string and a lower tubular member (mandrel) that telescopes inside the housing and threads onto an other part of the drill string. The mandrel and housing include complementary splined sections that prevent relative rotational movement of the mandrel and housing.
The purpose of mechanical drilling jar is to dislodge stuck pipe or drill tools from the well bore.
It works by impact, and for that purpose the mechanical drilling jar is designed to apply a controlled impact force to the lower end of the drill string. The impact may be applied in the up hole ; 30 direction (upon movement of the jar upward) or the down hole direction (upon movement of the jar downward).
It is known to provide such a mechanical drilling jar as described in Canadian patent no.
l,221,960 issued May 19, 1987, to Oil Patch Group Inc.
A copy of Figure 1 of the patent is shown here as Figure 1 in this patent document for ease of reference. In that patent there is described a ,~J ~,IJ ~ S .
mechanical drilling jar in which the uphole and downhole impact forces are transmitted across respective pairs of impact surfaces (35, 37 and 39, 40)r one impact surface of each pair being on the housing and one on the mandrel. The housing is composed of splined housing 2, latch housing 3 and top sub 4 each threaded together with threaded sections 27, 28, 29 and 30 and sealed with seals 32. The housing terminates in threaded section 31 for engagement with the next higher part of the drill string. The mandrel is formed in two parts, a splined -mandrel 1 and a knocker mandrel 5 which are threaded together with threaded sections 20 and 21 and sealed with seal 22, and terminates in a threaded end 23 for engagement with the next lower part of the drill string. The mandrel has splines 33 that engage with splines 36 of the housing. The knocker mandrel 5 has an upper end 24 that threads onto an oversize safety nut 25.
The housing and mandrel are connected and disconnected to each other by a latch assembly including a first latch ring 7, a second latch ring 8 and a split collet 6 disposed between the first and second latch rings. The split collet 6 has pyramidal teeth 14 on its interior surface that are engageable and disengageable with pyramidal teeth 15 on the outer surface of the mandrel. The mandrel and housing are sealed together by seals 12. The first latch ring 7 abuts against a shoulder 13 on the housing and the second latch ring 8 abuts against a plurality of Belville springs 11 which in turn abut against a shoulder 42 of the housing. The latch rings are connected to the split collet through latch pins 9A
and 9~ and it is to this connection mechanism between the latch rings and the split collet that the present invention is directed. The latch pins 9A and 9B
translate axial compression forces from the Belville springs into radially inwardly directed forces that tend to keep the split collet engaged with the mandrel.
In operation, the drilling jar described in Canadian patent no. 1,221,960 works as follows.
Firstly will be described the upward jar. An upward force is applied to the drill string by pulling on the upper end of the drill string. Upward forces are transmitted across the shoulder 13 through the first latch ring 7, latch pin 9A and the split collet 6 to the knocker mandrel 5. The angles of the faces of the teeth on the mandrel and the teeth on the split collet tend to translate the upward force into a radially outwardly directed force. When a preset level of the upward force is reached, that is when the outward force overcomes the inward force from the Belville springs, the split collet 6 moves outward, disengaging from the knocker mandrel 5, and the housing moves upward until the surfaces 39 and 40 impact each other and transmit a jarring force to the knocker mandrel.
For the downward jar, compressional force is imposed on the housing and is transmitted through shoulder 42, Belville springs 11, latch ring 8, latch pin 9B and split collet 6 to knocker mandrel 5. Again, the inclined faces of the teeth on the mandrel and on the split collet tend to translate this compressional force into a radially outwardly directed force. At a preset level of compression, the outward forces on the split collet overcome the inward forces and the split collet 6 moves outward, disengaging from the mandrel 5. The freed housing then moves downward until impact . f, i ~ I f ~ ~ ~
surfaces 35 and 37 meet transmitting a downward jarring force downhole through the splined mandrel 1.
If any of the joints fail, safety nut 25 is designed to engage shoulder 43 on the top sub 4 and prevent 5disengagement of the mandrel and the housing.
The preset tension and compression at which the split collet 6 disengages from the knocker mandrel 5 is adjustable in part by the force exerted by the Belville springs. The ratio of the downward to the 10upward jarring force is adjustable by the length of the latch pins. Incorrect adjustment of the latch pins can result in the failure of the collet to disengage or its premature disengagement. The latch pins are also easily broken since strong forces are transmitted 15by them.
~; The inventor has found that omission of the latch pins and use of opposed inclined faces results in considerable wear of the faces, and considerably greater pull required for the trigger level to be 20reached. Also, when the jar is fired (the split collet ;~ disengages from the mandrel), the split collet comes out at high speed and impacts heavily against the ` housing. Therefore, the use of opposed inclined faces is not recommended.
25There is therefore proposed an improvement to the mechanical drilling jar proposed in Canadian patent no. 1,221,960 in which the latch pins are replaced by roller bearings placed in inclined slots formed between the latch rings and split collet.
:
BRIEF DESCRIPTION OF THE DRAWINGS
There will now be described a preferred embodiment of the invention, with reference to the drawings, by way of illustration, in which like numerals denote like elements and in which:
Figure 1 is a longitudinal section of a prior art mechanical drilling jar;
Figure 2 is a longitudinal section of a latching mechanism according to the invention showing the latching mechanism engaged;
Figure 3 is a longitudinal section of a latching mechanism according to the invention showing the latching mechanism disengaged;
Figure 4 is a cross-section along the line 4-4 of Figure 2;
Eigure 5 is a cross-section along the line 5-5 of Figure 3; and Figure 6 shows a detailed section of a roller bearing for use with the invention.
DET~ILED DESCRIPTION ~F PREFERRÆD EMBODIMENTS
As noted and discussed above in the background section of this patent document, Figure 1 shows the prior art mechanical drilling jar. Figures 2l 3, 4 and 5 show the working of an improvement of that drilling jarl and the same numerals have been retained in those Figures to identify elements that have a common function and design. The design and function of common elements are therefore not described here, since they are set out above in the background and summary of the invention.
While the mandrel and housing are shown in two sections and three sections respectively, each threaded and sealed together, each of the mandrel and ~ J~
housing forms a unitary part that moves axially as a unit. Therefore in this detailed description and in the claims it will be understood that when the mandrel is referred to it means the combined splined and knocker mandrel and when the housing is referred to it means the combined splined housing, latch housing and top sub.
Referring to Figures 2, 3, 4 and 5, there is shown a mandrel 45 (the part shown is the knocker mandrel) and housing 46 (shown are the latch housing and the top sub). Disposed between first shoulder 13 and second shoulder 42 is a latch mechanism comprising, in order, a first latch ring 7, a plurality of first roller bearings 19, a split collet 6, a plurality of second roller bearings l9A, a second latch ring 8, and a plurality of Belville springs 11.
The components of the latch mechanism are longer than the distance between the shoulders 13 and 42, which compresses the Belville springs to place a preset compression on the latch mechanism that can be adjusted by choosing the number of Belville springs or by adding or removing spacers. The Belville springs form spring means disposed between the second latch ring and the second shoulder on the housing. While such springs are preferred, they may be replaced by other spring means.
The first roller bearings 19 roll on first inclined faces 51 machined into the first latch ring 7 to form grooves disposed circum~erentially about the first latch ring. The first roller bearings 19 also roll on second inclined faces 52 machined into one end of the split collet 6 to form a second set of grooves disposed circumferentially about the split collet. The inclined faces 51 and 52 are complementary to each other and during assembly are placed opposite each other with a roller bearing in each groove.
The second roller bearings l9A roll on third inclined faces 53 machined into one end of the split collet 6 to form a third set of grooves disposed circumferentially about the split collet. The second roller bearings l9A roll on fourth inclined faces 54 machined into the second latch ring 8 to form a fourth set of grooves disposed circumferentially about the second latch ring. The grooves 53 and 54 are also complementary to each other as with the grooves 51 and 52.
The roller bearings are best shown in Figure 6 which is exemplary of each of the grooves. The groove terminates in a flange 55 which prevents the roller bearing from rolling out of the groove. The faces 51, 52, 53 and 54 are inclined in a manner so that axial forces across the faces tend to move the ; split collet 6 radially inward towards the mandrel. It ; 20 is these forces that tend to maintain the split collet 6 engaged with the mandrel 45 as shown in Figures 2 and 4.
The operation of the latch mechanism is as follows. For a downward jar, the housing is urged downward (placed in compression) and the downward forces are transmitted through shoulder 42, Belville springs 11, second latch ring 8, second roller bearings l9A and pyramidal teeth 14, 15 to the mandrel 45 as shown in Figures 2 and 4. At a preset force, the outward force exerted by the inclined faces of the pyramidal teeth on the split collet 6 overcomes the radially inward directed force across the second roller bearings and forces the split collet 6 rapidly outward, leaving the mandrel 45 and housing 46 disengaged and free to move axially as shown in Figures 3 and 5. The downward force on the housing 46 will urge it downward relative to the mandrel and the impact surfaces 35, 37 (Figure 1) will engage and transmit a jarring force downhole. By pulling up on the housing, the latch mechanism can be returned to the original position with pyramidal teeth engaged.
For an upward jar, the housing is urged upward (placed in tension) and the upward forces are transmitted through the shoulder 13, first latch ring 7, first roller bearings 19 and split collet 6 to mandrel 45. The inclined faces of the pyramidal teeth will tend to urge the split collet 6 outward, and at a preset force, the outward force exerted through the inclined faces of the pyramidal teeth will overcome the force exerted by the Belville springs and the roller bearings on the split collet 6. The split collet 6 will then move rapidly outward and the housing 46 will move upward relative to the mandrel 45 until the i~pact surfaces 39 and 40 (Figure 1) meet and transmit a jarring force into the mandrel.
The force required to disengage the split collet 6 depends on several factors such as (1) the angle and smoothness of the faces on the pyramidal teeth (preferably about 45), (2) the angle of the inclined faces 51, 52, 53 and 54 (which is preferably at an angle of 30 to a radius of the tool) and (3) the force applied by the Belville springs.
The forces transmitted through the second roller bearings 19A primarily holds the split collet 6 against the mandrel 45 when the jarring tool is operated for a downward jar (housing under compression). By comparison, forces transmitted through both sets of roller bearings l9,19A hold the s~
split collet 6 against the mandrel 45 when the jarring tool is operated for an upward jar. Consequently, the force required to dislodge the split collet 6 for a downward jar will be less than the force required to dislodge the split collet 6 for an upward jar. The desired predetermined tension or compression at which the split collet 6 disengages may be set by adjustment of the number of Belville springs and changing the angle of the inclined faces 51, 52, 53 and 54.
Generally, the less the angle of the inclined faces, the lower the force required to dislodge the split collet 6.
The split collet is preferably made of ASTRALOYtm, and the mandrel in the area of the pyramidal teeth is preferably induction hardened. The joints between the housing components are preferably stress relieved. In a 6" tool, the roller bearings are preferably about 1~" long.
A person skilled in the art could make immaterial modifications to the invention described and claimed in this patent without departing from the essence of the invention.
For example, the lower latch ring could conceivably be omitted, and -the grooves placed on the housing, but since the grooves have to be milled, this is very difficult to make. The grooves could also be made arcuate, so that they begin at an incline of about 35 and change gradually to an incline of about 25, so that the inclination decreases with increasing distance from the center of the tool. This would result in a slightly higher level of compression or tension at which the split collet will disengage from the mandrel, but would mean that the disengagement would be progressively faster.
Claims (4)
1. A well jarring tool comprising:
a housing having first and second shoulders;
a mandrel disposed telescopically within the housing and having a first gripping surface;
a first pair of impact surfaces, one surface of which is on the housing and the other of which is on the mandrel;
a second pair of impact surfaces, one surface of which is on the housing and the other of which is on the mandrel;
and a latch mechanism for locking the housing and mandrel together against relative axial movement until a preset compression or tension of the mandrel and housing relative to each other is applied at which the latch mechanism unlocks permitting relative axial movement of the mandrel and housing and subsequent sudden engagement of one of the pairs of impact surfaces, the latch mechanism comprising;
a split collet having a second gripping surface engageable with the first gripping surface on the mandrel and having a plurality of inclined first and second faces at first and second ends of the split collet respectively;
a plurality of third and fourth inclined faces disposed circumferentially around the split collet and paired with respective ones of the plurality of first and second inclined faces;
a plurality of bearings disposed between respective pairs of the inclined faces;
and means to provide compression forces across the inclined faces, whereby the compressional forces urge the first and second gripping surfaces together.
a housing having first and second shoulders;
a mandrel disposed telescopically within the housing and having a first gripping surface;
a first pair of impact surfaces, one surface of which is on the housing and the other of which is on the mandrel;
a second pair of impact surfaces, one surface of which is on the housing and the other of which is on the mandrel;
and a latch mechanism for locking the housing and mandrel together against relative axial movement until a preset compression or tension of the mandrel and housing relative to each other is applied at which the latch mechanism unlocks permitting relative axial movement of the mandrel and housing and subsequent sudden engagement of one of the pairs of impact surfaces, the latch mechanism comprising;
a split collet having a second gripping surface engageable with the first gripping surface on the mandrel and having a plurality of inclined first and second faces at first and second ends of the split collet respectively;
a plurality of third and fourth inclined faces disposed circumferentially around the split collet and paired with respective ones of the plurality of first and second inclined faces;
a plurality of bearings disposed between respective pairs of the inclined faces;
and means to provide compression forces across the inclined faces, whereby the compressional forces urge the first and second gripping surfaces together.
2. The well jarring tool of claim 1 in which the latch mechanism comprises:
a first latch ring abutting against a first shoulder on the housing and having a plurality of first inclined faces forming first grooves disposed circumferentially around the first latch ring;
a plurality of first roller bearings disposed in the first grooves on the first latch ring;
a split collet having at one end a plurality of second inclined faces forming second grooves for receiving the first roller bearings, having a second gripping surface removably engageable with the first gripping surface on the mandrel and having at the other end a plurality of third inclined faces forming third grooves;
a plurality of second roller bearings disposed in the third grooves on the split collet;
a second latch ring having a plurality of fourth inclined faces forming fourth grooves for receiving the second roller bearings; and spring means disposed between the second latch ring and the second shoulder on the housing.
a first latch ring abutting against a first shoulder on the housing and having a plurality of first inclined faces forming first grooves disposed circumferentially around the first latch ring;
a plurality of first roller bearings disposed in the first grooves on the first latch ring;
a split collet having at one end a plurality of second inclined faces forming second grooves for receiving the first roller bearings, having a second gripping surface removably engageable with the first gripping surface on the mandrel and having at the other end a plurality of third inclined faces forming third grooves;
a plurality of second roller bearings disposed in the third grooves on the split collet;
a second latch ring having a plurality of fourth inclined faces forming fourth grooves for receiving the second roller bearings; and spring means disposed between the second latch ring and the second shoulder on the housing.
3. The well jarring tool of claim 2 in which the inclined faces are inclined at an angle of about 30° to a radius of the tool.
4. The well jarring tool of claim 2 in which the inclined faces have a gradually decreasing inclination with increasing distance from the center of the tool.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2058703 CA2058703A1 (en) | 1992-01-02 | 1992-01-02 | Latch mechanism for use in association with a mechanical drilling jar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2058703 CA2058703A1 (en) | 1992-01-02 | 1992-01-02 | Latch mechanism for use in association with a mechanical drilling jar |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2058703A1 true CA2058703A1 (en) | 1992-05-11 |
Family
ID=4149024
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2058703 Abandoned CA2058703A1 (en) | 1992-01-02 | 1992-01-02 | Latch mechanism for use in association with a mechanical drilling jar |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2058703A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5476148A (en) * | 1993-10-26 | 1995-12-19 | Labonte; Raymond | Tool for maintaining wellbore penetration |
-
1992
- 1992-01-02 CA CA 2058703 patent/CA2058703A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5476148A (en) * | 1993-10-26 | 1995-12-19 | Labonte; Raymond | Tool for maintaining wellbore penetration |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |