Abstract:
The down hole jar tool is a tool used to apply jarring forces to objects that may be obstructing the path of a down hole, or above-ground operation that requires a repetitive jarring action to dislodge or remove such objects. The tool is used by providing a linear input to a mandrel portion that draws back against a compressible unit of predetermined resistance until a releasing means abruptly releases the mandrel portion. The mandrel portion then rapidly moves in the direction of the linear input until it encounters a stationary anvil, which produces the desired jarring action. This tool may also be combined with accelerators and/or valves, as well as other tools, to create a more substantial jarring impact.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to downhole fishing and drilling operations, or removing obstructions to a drilling line when such a line becomes lodged or otherwise stuck in a well bore. Conventional means of downhole retrieval are dubious, and usually involve attempting to actuate the entire work string in the hope of dislodging it or removing an obstruction. Often this is unsuccessful either because the work string cannot jar loose the obstructions, or adequate motion cannot be effected in the well bore. Consequences of this failure to remove the obstruction can be failure of the well to produce at all or in part, also, current methods of removing obstructions can result in line breakage, both of which result in having to relocate the drilling operation, which necessarily involves lost time and money. 
     The present invention is able to attempt to actuate a lodged object in the path of the drilling path without moving the work string, which results in reduced trauma and friction and prevents work hardening of the work string. The tool can also have various other applications, such as drilling, retrieving or driving other tools that may be attached to it, or in any application, down hole or otherwise, that may require such a jarring action. 
     OBJECTS OF THE INVENTION 
     One objective of this invention is to provide a device capable of maintaining tensile force on a drilling work string while dislodging an object that may be interfering with the well operation. 
     Another objective of the invention is to provide a device that is more efficient at dislodging obstructions interfering with well operations. 
     Still another objective of the invention is to provide a device that can be placed into any confined space and perform a jarring action, or drive other tools that require linear input. 
     Other objects and advantages of this invention shall become apparent from the ensuing descriptions of the invention. 
     SUMMARY OF THE INVENTION 
     According to the present invention, the down hole jar tool is a tool used to apply jarring forces to objects that may be obstructing the path of a down hole, or above-ground operation that requires a repetitive jarring action to dislodge or remove such objects. The tool is used by providing a linear input to a mandrel portion that draws back against a compressible unit of predetermined resistance until a releasing means abruptly releases the mandrel portion. The mandrel portion then rapidly moves in the direction of the linear input until it encounters a stationary anvil, which produces the desired jarring action. This tool may also be combined with accelerators and/or valves, as well as other tools, to create a more substantial jarring impact. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings illustrate an embodiment of this invention. However, it is to be understood that this embodiment is intended to be neither exhaustive, nor limiting of the invention. It is but one example of some of the forms in which the invention may be practiced. 
     FIGS. 1A-1D show diametrical longitudinal cross-sections of the hammer assembly in the “up” or “fired” position. 
     FIGS. 2A-2D show diametrical longitudinal cross-sections of the hammer assembly in the “down” or “re-cock for firing” position. 
     FIGS. 3A-3D show diametrical longitudinal cross-sections of the hammer assembly in the “neutral” or “ready to fire” position. 
     FIG. 4 shows an end cross-sectional view of the bearing assembly shown in FIG.  1 D. 
     FIG. 4A shows a perspective view of the bearings shown in FIG.  4 . 
     FIG. 4B shows an elevational view of the mushroom-shaped segments. 
     FIG. 5 shows an enlarged detail view of a portion of FIG.  1 C. 
     FIG. 5A shows a perspective view of the Belleville washers shown in FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Without any intent to limit the scope of this invention, reference is made to the figures in describing the preferred embodiments of the invention. Referring to FIGS. 1 through 5, FIGS. 1A through 1D show the invention in the “up” or “fired” position. FIGS. 2A through 2D show the invention in the “down” or “re-cock” position, and FIGS. 3A through 3D show the invention in the “neutral” or “ready to fire” position. 
     The flow-activated hammer assembly  123  is comprised mainly of six components, outer mandrel  101 , latching and unlatching sleeve  202 , inner mandrel  105 , kinetic energy sleeve  125 , reloading energy sleeve  205 , and latching and unlatching ring  206 . Inner mandrel  105  resides within outer mandrel  101 , and kinetic energy sleeve  125  is disposed between the two. Outer mandrel  101  is stationary, while inner mandrel  105  is free to move telescopically within outer mandrel  101 . 
     Outer mandrel  101  can be a cylindrical housing used to contain all the parts of flow-activated hammer assembly  123 . On the inner surface of outer mandrel  101 , there will be re-cock groove  209  and firing groove  210 . These grooves are shaped to receive latching and unlatching ring  206 . The grooves can have various depths and shapes depending upon the characteristics of latching and unlatching ring  206 . 
     Inner mandrel  105  is a cylindrical mandrel which at its uppermost end will be connected to a driving force, such as the flow-activated valve assembly  100  discussed below, or by any other linear input, be it mechanical or otherwise. Inner mandrel  105  can be hollow if used in conjunction with a hydraulic tool to permit hydraulic fluid to exit from such a tool, or it can be substantially solid if a mechanical means is used to drive the tool. Where inner mandrel  105  engages latching and unlatching sleeve  202 , there is inner mandrel groove  211  cut to permit inner mandrel  105  to engage latching and unlatching ring  206 . Shortly beyond inner mandrel groove  211 , inner mandrel&#39;s  203  diameter decreases to permit accommodation of kinetic reloading sleeve  205  on its outside perimeter. This change in diameter forms retaining lip  214 . 
     Kinetic energy sleeve  125  is held in place radially by inner mandrel  105  and outer mandrel  101 , and held in place longitudinally by outer mandrel coupling  206  which provides upper shoulder  207  and by latching and unlatching sleeve  202 . Kinetic energy sleeve  125  can be any type of variably compressible substance or similar assembly, such as belleville washers, stacked chevron washers, springs, nitrogen gas or hydraulic fluid. An example of such a compressible assembly is shown in FIGS. 5 and 5A, where belleville washers  501  are stacked in a manner used to create kinetic energy, namely, face-to-face. 
     Latching and unlatching sleeve  202  is also held in place radially by outer mandrel  101  and inner mandrel  105 , and secured longitudinally by kinetic energy sleeve  125  and by reloading energy sleeve  205 . Latching and unlatching sleeve  202  is designed such that latching and unlatching ring  206  can be secured at a selected point along latching and unlatching sleeve&#39;s  202  length. 
     Examining FIG. 4, latching and unlatching ring  206  is comprised of a retaining ring  401 , as well as bearings  402 , which can either be in a capsule shape, or that of a cylinder with rounded edges, as in FIG. 4A, or in a “mushroom” shape, depending upon application. 
     Reloading energy sleeve  205 , like the previous two components, is mounted between outer mandrel  101  and inner mandrel  105 . Longitudinally, it is secured by latching and unlatching sleeve  202 , and by an outer mandrel finisher  208 . Reloading energy sleeve  205  can be any type of variably compressible substance or similar assembly, such as belleville washers, stacked chevron washers, springs, nitrogen gas or hydraulic fluid. 
     Washers  212  may be implemented at various points between moving parts to reduce friction and/or wear, and o-rings  213  can be used at strategic points to keep the insides of the tool clean, and/or prevent fluid from entering portions of the tool if needed. 
     In operation, a driving force will be applied to extending mandrel  124 , such that extending mandrel  124  will be pulled upward, at which point latching and unlatching ring  206  will be located in inner mandrel groove  211  and will be unable to move past retaining lip  214 , thus restricting movement of extending mandrel  124 . As force is maintained on extending mandrel  124 , retaining lip  214  and latching and unlatching ring  206  will begin to travel upward against the force of kinetic energy sleeve  125 . The tool will now be in the “ready to fire” position, illustrated by FIGS. 3A through 3D. 
     This force will continue until sufficient energy is applied to extending mandrel  124  to overcome the configured strength of jar energy sleeve  204 , at which point jar energy sleeve  204  will permit a small amount of longitudinal travel of latching and unlatching sleeve  202 , causing latching and unlatching ring  206  to locate in firing groove  210 . At this time, extending mandrel  124  will no longer be restricted in longitudinal movement by latching and unlatching ring  206  and retaining lip  214 , and will rapidly move upward, until it strikes a aft inner shoulder  215 , causing an upward jarring force on the tool, and leaving the tool in the “fired” position, as illustrated in FIGS. 1A through 1D. 
     After this upward jar is delivered, the tool will begin to return downward to the starting position. As it does, the retaining lip  214  will encounter latching and unlatching ring  206 , moving it out of firing groove  210  and down the body of the tool, until it reaches re-cock groove  209 . Here, latching and unlatching ring  206  will drop into re-cock groove  209 , permitting retaining lip  214  to move past it. Now, reloading energy sleeve  205  will apply predetermined upward force, typically less than that of kinetic energy sleeve  125 , but sufficient to move latching and unlatching ring  206  forward in re-cock groove  209 . Extending mandrel  124  then begins moving upward again, and latching and unlatching ring will engage inner mandrel groove  211 , thus beginning the firing stroke, illustrated in FIGS. 2A through 2D. 
     The tool, in the aforementioned embodiment, will apply an upward jarring force when operating; however, it may also be configured to provide a downward jarring force if needed. This may be accomplished by reconfiguring the kinetic energy sleeve  125  and reloading energy sleeve  205  to provide upward resistance instead of downward resistance, thereby causing the jarring force to impact in the reverse direction from that illustrated above. 
     This tool is also intended to be used in conjunction with a flow-activated valve, such as the one in co-pending application entitled “Flow-Activated Valve,” which is hereby incorporated by reference in its entirety. Such a tool would be attached as the driving force of the jar tool by being attached to extending mandrel  124 . The flow-activated valve is described below. 
     The “top” of tool assembly  100  starts at the top of FIGS. 1A,  2 A, and  3 A. Shown is outer mandrel  101 , which in the embodiment of the above-mentioned FIGS., is threadably separable into several parts to facilitate assembly and maintenance by way of several threaded joints  102 . The tool assembly  100  is shaped to permit connection to a hydraulic source and/or other threaded tool at joint  103 . Outer mandrel  101  also has hydraulic exhaust ports  104 . Located within outer mandrel  101  is the inner mandrel  105 , which, in this embodiment, is threadably attached to outer mandrel  101  and is separable into parts by way of threaded connections  106 . Inner mandrel  105  has hydraulic fore exhaust ports  107  and aft exhaust ports  108 . Hydraulic fluid is also able to exhaust at the lower end of inner mandrel  105  through mill slots  109 . These parts are all stationary while the tool is being operated. 
     Some of the parts of tool assembly  100  are moving while tool assembly  100  is operated, the first of which is reciprocating valve  110 . Like outer mandrel  101  and inner mandrel  105 , reciprocating valve  110  has, in the embodiment shown, been cast as separable pieces joined by threadable connections  111 . Reciprocating valve  110  has fore hydraulic exhaust ports  113  and aft hydraulic exhaust ports  114 . Various shoulders are along reciprocating valve  110  and its path of travel, such as aft hammer shoulder  119 , which engages fore inner shoulder  120  of outer mandrel  101  on the down stroke. There also exists a reciprocating sleeve closing shoulder  118 , and a reciprocating sleeve opening shoulder  121  which is used to actuate reciprocating sleeve  115  during operation. Outer mandrel  101  has a top shoulder  122  where outer mandrel  101  joins inner mandrel  105 . Another moving part, reciprocating sleeve  115  is mounted to engage the outer portion of inner mandrel  105 , and to slide back and forth along a small portion of inner mandrel  105 . As in reciprocating valve  110 , reciprocating sleeve  115  has fore hydraulic exhaust ports  116  and aft hydraulic exhaust ports  117 . 
     It should be recognized that various threadable connections  111 , while shown, are not essential for proper operation, and the invention can be practiced with or without threadable connections  111  on reciprocating valve  110 , outer mandrel  101 , or inner mandrel  105 . Parts may be cast in fewer or more pieces, depending upon need and adoption for a particular use. In any embodiment, o-rings  213  may be strategically placed throughout the tool to prevent fluid or other materials that may be passing through or around the tool from entering moving part areas of the tool. 
     During operation, driving fluid, such as hydraulic fluid, gas or similar is pumped or otherwise introduced into tool assembly  100  at joint  103 . The fluid then passes within outer mandrel  101 , to inner mandrel  105 , and while tool assembly  100  is in the “up” position, the fluid will exit via aft hydraulic ports  108  of inner mandrel  105 , aft hydraulic ports  114  of reciprocating sleeve  115  and aft hydraulic ports  117  of reciprocating valve  110 , at which point the fluid will force reciprocating valve  110  to move away from the “top” of tool assembly  100 . Eventually, reciprocating valve  110  will engage aft hammer shoulder  119 , creating an impact in the downward direction, as well as marking the end of the downward stroke. 
     Simultaneously with the above action, reciprocating sleeve opening shoulder  121  of reciprocating valve  110 , as it slides, will cause reciprocating sleeve  115  to move down the inner mandrel  105  in the same direction, effectively closing aft hydraulic ports  108  of inner mandrel  105 , and opening fore hydraulic ports  107  of inner mandrel  105 . At this time, the fluid will be permitted to exit via the lower end of inner mandrel  105  through mill slots  109 , at which point it may exit from end  122 . This leaves tool assembly  100  in the “down” position. 
     At all times during operation, additional fluid is being pumped into joint  103 , but because inner mandrel  105  hydraulic aft exhaust ports  108  are now closed, the fluid exits through the inner mandrel  105  hydraulic fore exhaust ports  107 , which forces reciprocating valve  110  to move in the direction of joint  103  due to fluid pressure being applied to reciprocating valve  110 , that being the path of least resistance. This movement continues until reciprocating valve  110  reaches top shoulder  122 , at which point reciprocating valve  110  engages top shoulder  122  and creates an impact in an upward direction, marking the end of the upward stroke. At this point, reciprocating valve  110  will have traveled far enough to expose outer mandrel&#39;s  101  hydraulic exhaust ports  104  so that fluid will exit tool assembly  100 . When reciprocating valve  110  is in this position, reciprocating sleeve closing shoulder  118  will have moved reciprocating sleeve  115  to its original, or “up” position, thus restarting the cycle. 
     To assist in the down hole operation, accelerator  123  may be attached to bottom end of tool assembly  100  in order to exaggerate the vibratory motion created by tool assembly  100 . Accelerator  123  is constructed of extending mandrel  124 , which is shaped to fit within outer mandrel  101 , but also to permit a compressible kinetic energy sleeve  125  to fit between the walls of outer mandrel  101  and extending mandrel  124 , and further be connected to reciprocating valve. Kinetic energy sleeve  125  is retained in place by being situated between a fore accelerator shoulder  126  and an aft accelerator shoulder  127 . 
     In this manner, when reciprocating valve  110  is performing a downward stroke, it is energizing a compressible kinetic energy sleeve  125 , such as a spring, belleville washer assembly, stacked chevron washer assembly, risked washer springs, hydraulic fluid or other known similar devices. This is accomplished when fore accelerator shoulder  126  is moving downwardly and compresses kinetic energy sleeve  125 . When reciprocating valve  110  reverses direction, it is thrust forward with the contained kinetic energy stored in compressible kinetic energy sleeve  125 , thus creating a more powerful impact on the upstroke. Similarly, compressible kinetic energy sleeve  125  can be configured to have the reverse effect, or to amplify the downward stroke. This can be done by reversing compressibility of the spring to change the direction of the release of kinetic energy. 
     Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.