US2250574A

US2250574A - Explosive rotary jar for deep well equipment

Info

Publication number: US2250574A
Application number: US259152A
Authority: US
Inventors: Eugene W Dodge
Original assignee: THOMAS TILDEN VAUGHN
Current assignee: THOMAS TILDEN VAUGHN
Priority date: 1939-03-01
Filing date: 1939-03-01
Publication date: 1941-07-29
Anticipated expiration: 1958-07-29

Description

July 29, 1941. E. w DODGE EXPLOSIVE ROTARY JAR FOR DEEP WELL EQUIPMENT Filed March 1, 1939 5 Sheets-She t 1 LZW y 1941- E. w. DODGE 2,250,574

EXPLOSIVE ROTARY JAR FOR DEEP WELL EQUIPMENT Filed March 1, 1939 I5 Sheets-Sheet 2 July 29, 1941. E. w. DODGE EXPLOSIVE ROTARY JAR FOR DEEP WELL EQUIPMENT s Sheets-Sheet 5 Filed March 1, 1939 Patented July 29, 1941 UNITED STATES PATENT OFFICE EXPLOSIVE ROTARY JAR FOR DEEP WELL EQUIPMENT Eugene W. Dodge, Shatter, Calif., assignor of to Thomas Tilden Vaughn,

twenty-five per cent Shafter, Calif.

Application March 1, 1939, Serial No. 259,152

26 Claims.

what diflicult to remove, and also in the re-,

an upward stroke with an upwardly directed hammer-like action producing the jarring blow.

In contradistinction to these types of jars my invention comprehends the use of an explosive in my particular type of assembly of jars, and the force of the blows delivered while the upward pull is at its maximum and such jars being inserted in the string of tools above the portion of the drilling equipment to be removed. Then on the discharge of the explosive an exceedingly high pressure is directed downwardly through the hydraulic fluid. This causes a discharge at the bottom of the tool under exceedingly high pressure and giving an upward or jarring action on the assembly of tools caught in the well and producing an upward movement ofthe lower movable element of the explosive operated jar.

In view of the fact that more than one explosive may be necessary and in fact quite a large number would usually be needed another feature of my invention includes an equipment for charging explosive cartridges into a string of drillpipe and having these carried downwardly by the downward flowing hydraulic fluid in its circulation under pump pressure. This involves an equipment of a valve by which the cartridge may be inserted and bodily moved until inalignment with the flow of the slushing fluid, that is, in vertical alignment with the string of drill .pipe and then is carried downwardly by the slushing fluid. This necessitates a valve which may be closed and sealed against the high pressure of the hydraulic fluid.

Another feature of my invention involves the construction .of an explosion and firing chamber for the cartridges in which a firing pin is centrally positioned and causes the ignition of the cartridge dropping and forced downwardly by the hydraulic fluid. Above this chamber I employ a check valve, this being normally opened when the fluid is circulating downwardly but whichbecomes closed due to the pressure of the explosion which manifestly exerts a force both upwardly and downwardly and when the check valve is closed there is no upward flow of the slushing mud and the flow of slushing mud is directed downwardly under exceedingly high pressure.

My invention has further characteristics in the type of cartridges used. Where the hydraulic pressures are more or less moderate I use a cartridge of a type which is blown to pieces and made of such material and constructed so that the shell of the cartridge breaks up into a multitude of small pieces which are carried. out by the slushing fluid. If the. natural flow of this fluid by a pumping does not completely carry out the disintegrated cartridge the remaining particles are blown out with the slushing fluid on the succeeding explosions.

My invention also comprehends a type of electrically discharged cartridge designed principally for use at great depths where the hydraulic pressure is very great. In this case the shell of the cartridge is made of a substantial tube but in both type of cartridges the ends may blow out.

In the electrically fired construction the jar in the lower portion is provided with a sealed in electric battery with electric leads extending to 'with an annular space between such pipe and the wall of the barrel part of the explosion chamber. A further feature and characteristic of my invention is that I provide for a rotary drive between the upper and lower parts of the jar which have relative longitudinal movement in.

order to carry the rotational torque from the rotary table at the top of the well to the drill bit or other tool at the bottom and I also provide for a complete flow of the circulating fluid and during the period of explosion for the release and outward flow of the fluid above the explosion chamber. My invention also comprehends devices for admitting hydraulic fluid to the jar and a string of drill pipe in order that thismay not enter the hole dry but may become filled with the slushing fluid as the equipment descends in the well.

As jars, are frequently employed to remove tubular tools or equipment from a well such as drill pipe with drill bits stuck in the well and frequently designated as a fish and also for removing casing, the equipment below the jar proper and below the explosion chamber may be directly connected to the tubular tools such as drill pipe and casing, therefore the liquid below the explosion chamber is forcefully discharged downwardly through the tubular structure below the explosion chamber and through the tubular flsh" such as drill pipe or the casing and thus produces a violent upward flow through the material freezing the fish in the well hole or adjacent the formation in the casing to be removed.

My invention is illustrated in connection with the accompanying drawings, in which:

Fig. 1 is a vertical diametrical section of an upper portion of the jars.

Fig.2 is a similar diametrical section continuing with the lower portion of the jars, there being a partial overlap of Figs. 1 and 2.

Fig. 3 is a vertical diametrical section of a cartridge injection or insertion valve located above the ground level and illustrated connected to a string of drill pipe.

Fig. 4 is adetail section on the line 4-4 of Fig. 3 with the plug of the valve in a partial valve closing position.

Fig. 5 is a vertical diametrical section showing an electric battery assembly connected to the bottom of the lower portion of the Jars.

Fig. 6 is a horizontal section on the line 6-6 of Fig. 1 in the direction of the arrows.

Fig. 7 is a horizontal section on the line 1-1 of Fig. 2 in the direction of the arrows.

Fig. 8 is an elevation assembly drawing with various parts broken illustrating in diagram the jars as inserted in the well.

Fig. 9 is a side elevation partly broken away of one form of cartridge for operating at great depths where the pressure is excessive, such cartridge being of a type to blow out at the ends.

Fig. 10 is an enlarged diametrical section through the ignition devices of the cartridge of Fig. 9. Fig. 11 is a side elevation partly broken away I ground surface l2 and there being a casing l3 extending partly downwardly into the well. Manifestly the horizontal measurements are considerably greater than the vertical to give an adequate illustration. Employing the jars as in my invention an upper length of drill or equivalent pipe I 5 is by the common practice suspended by the well derrick by cables or the like so that an upward pull may be given on the whole assembly and also by means of a swivel such as well known in the art a connection is made for pumping the hydraulic slushing fluid downwardly through the drill pipe and system to the end of the drill string and a tool mounted thereon. An

. injection valve is also located above the ground level and this is connected to 'the string of drill. pipe, the connection being illustrated in Figs. 3

and 4. Connected below the valve there is a string of drill or other pipe designated 2| to which is connected the upper portion of the jar 22 and suspended below the upper portion there.

is the lower portion 23 which may telescope upwardly into such upper portion, Attached to the bottom end of the lower portion of the jar I provide the electric battery sub 24. 25 illustrates a string of drill pipe or the equivalent which leads downwardly to the tool or the other well equipment to be removed from the well. This may have fishing tools attached thereto where it is necessary to remove the tools or articles from the well by a fishing operation.

Considering the various elements in detail, the

valve 20 has a valve housing designated 30, this presenting a bottom wall 3|, two similar sides 32, an end wall 33, a front wall 34 and a removable cover or top 35. The cover has preferably formed integral therewith a threaded box 36 for threading the assembly on the drill string or pipes l5. Also formed integral with the bottom wall 3| there is a stub pipe 31 illustrated as having a threaded end to have a threaded engagement with the drill string 2|. The cap has a cartridge inserting opening 38 which is tightly closed by a removable plug 33. There is also a. grease applying fitting 40 preferably attached to the top.

The cross sectional shape of the valve housing presents a flat bottom 4| and inclined opposite sides 42, the inside of the top also being .flat. The valve plug designated by the assembly numeral 45 is made of the same cross section as the inside of the housing, this plug therefore having a flat bottom surface 46 with two similar inclined surfaces 41- anda flat top 48. There is a vertical cartridge receiving opening 49 through the plug from top to bottom. The plug is moved in the housing by means of a threaded valve stem 50, this being threaded through an opening in the front end 34. A circular head 5| is mounted in a recess in the inner end of the plug and this head retained in place by a ring 62' attached to the plug by screws or the like. A hand operated wheel 53 is utilized to move the plug.

In view of the tremendous hydraulic pressure developed by the slushing fluid being pumped downwardly through the drill string, the jars and hence through the valve 20, it is necessary to have a tight seal at the plug but yet allow this to move with suflicient freedom. Therefore grease is forced in under high pressure through the grease applying fitting 40 and forms a film tightly packed at all of the contact surfaces of the plug with the housing and especially filling the slight space between the top'of the plug and the removable top of the housing. Therefore the plug 39 may be unthreadedfrom the opening 38 and with the plug in the retracted position a cartridge may be inserted through the opening 38 into the cartridge receiving opening, the lower end of the cartridge resting on the flat bottom 3| of the housing. The plug 39 is then replaced and the valve may be moved from the position of Fig. 3 to align the cartridge from the tubular drill string and the pipe section 31. The downward flowing slushing fluid then carries the cartridge with it. A movement of the plug and cartridge may be done so rapidly that there is very fluid the pumps may be stopped. When the cartridgeis discharged downwardly the plug is again retracted to its inactive position of Fig. 3.

As above mentioned the lengths of drill pipe 2I are connected by a threaded joint to the threaded end of the pipe 31 of the cartridge injection valve. This length of pipe may be as long as desired and necessary and has' attached to the bottom end thereof the upper portion 22 of the jars. This upper portion may be considered as the channel part of the jars and is illustrated with a box construction 60 connected by a threaded joint to the bottom end of the string of drill pipes. There is a substantial shoulder portion 6| preferably with a cone shaped slope 62 on the exterior. A heavy depending skirt 63 has a transverse lower end 64 and has an interior screw threaded portion 65 adjacent the bottom. Extending above this on the inside there is a fluted or splinedsection 66 extending to the top shoulder 61. The

shoulder portion has a large diameter bore 68 preferably equal to that of the drill pipe and by means of ,a screw threaded connection a guide pipe 69 is threaded in the shoulder]: portion.

There are a series of adjustable checkfby-pass valves I5, each of which is illustrated asih'a'ving a port I6 communicating with the'bore 68, a

valve I08 is retained in place by a ring I09. These check valves I05 are for the purpose of allowing an inflow of slushing fluid while the drill string and jars are being lowered into a well in order to lower the equipment so that it becomes filled with fluid instead of flowing this in dry or empty. The ports 85 in the guide pipe are for discharge or bleeding of the slushing fluid trapped in the fluted annular space inside of the skirt. A bronze packing ring H2 is mounted at the lower end of the head ml of the shank and seats on the upper surface 92 of .the collar 90. This is for the purpose of forming a fluid seal when the jars are under an upward strain and as they are being loweredinto the well.

The shank I00 has a screw threaded connection with the gun portion I20 'of the loweror male part of the jars. This gun portion has a heavy wall structure indicated at I2 I. It is preferably cylindricalon the outside" surface and has a structure. A large recess I24 forms an enlarge- I ment of the bore I22 and provides for the movethreaded enlarged recess 11 leading to'the but I side together with an adjusting threaded ring 18,

a complete spring I9 and a ball 80 forming normally a seal against the port I6. These are set so that in the normal operation the pressure of ment of a flap valve I25, this being hinged on "the pintle I26 which may be driven through the Wall structure I2I.- A spring I21 has'a thrust end I28 engaging one side of the'recess and urges the flap valve to its closed position. This flap the slushing fluid being forced downwardly does not open these check valves,'howe'ver when the downward flow of the slushing fluid is stopped by the explosive action hereunder described these operate. The guide pipe 69 is also provided with a series of ports 85 which communicate with the annular space between such guide pipe and the inside of the skirt ,63, that is, at the fluted section and open to the interior of thejguide pipe. A thrust ring 90 is threadedexteriorally and cylindrical on its inside surface. This has a threaded en gagement with the internal threads 65 on the skirt. A set screw 9| retains this collar in place. It preferably has a transverse upper surface 92 and also a transverse lower surface 93, this latter being in alignment with the bottom surface 64 of the skirt. A composition packing 95 is attached to the lower edge 64 of the skirt as by screws 96. This has a' substantially half circle rim 91. This composition may expand and become distorted under pressure and provides a fluid seal for the circulating fluid when the jars are in their collapsed or contacting position, that is, when the lower jaw element hereunder described contacts the compositionring 95. The

this guide pipe. The shank has an enlargement or head I'0I which is fluted or splined on the outside to flt the internal splined or fluted section 66 of the skirt 63. Inflow check valves I05, of which there are a series, include fluid ducts I06 extending vertically through the head I M and valve seats against the lower part .of the shank 'I00 at its screw threaded connection I23 and the How of the slushing fluid, as such fluid being having an intake port I01 which when the jars 'the sleeve I5I being seated on a shoulder.

forced downwardly under pump pressure maintains the flap valve open a sufficient amount for the proper flow of slushing fluid. The lower portion of the .bore I22 of the gun structure has a series of relatively deep longitudinal grooves I30, these being quite long and depending upon the length of the'gun structure. The bottom of the gun structure is shown as having a threaded pin joint I3I for attachment to the electric battery sub 24 which is described in detail hereunder.

The firing rod assembly I40 has a substantial block base I externally threaded and with a threaded support I42 on the interior of the hollow gun structure preferably adjacent the pin joint I3I. This head has a recess I43 extending upwardly from the bottom and is provided with a plurality of slushing fluid discharge ducts I44,

these being of sufficient number and size to acassembly I" which is illustrated in detail in,

Fig. 12. This includes a pointed firing pin I48 encased in an insulating sleeve I49, the latter being surrounded by a metal sleeve I60. This is slidable through an opening in the cap of an insulated sleeve I5I which is mounted in a recess in the upper part of the tubular firing rod I46, A packing I52 and packing gland I53 form a liquid tight seal. A plug I54 is threaded into the lower end of the-sleeve ISI, thus-there is a chamber within the sleeve which is filled with oil. A collar I66 is secured to the sleeve I56 of the firing pin and forms an abutment with the compression spring I6I', this reacting against the plug I54. The firing pin has a downward conducting extension I62 for purposes hereunder described. A set screw I63 retains the sleeve II in place and from rotation. The firing rod I45 has its upper end shaped into two diametrically opposite piercing prongs I65. When the firing of the cartridge is done electrically the plug I54 which is made of insulating material is provided with a contact plate I61 with an electric lead I68 extending downwardly. Another lead I69 is connected to a terminal I16 to the pipe. The sleeve I5I including the cap I53 is of non-electrical conducting material so that the center firing pin I53 is electrically insulated from the prongs I65.

The battery sub 24, note particularly Fig. 5, has the following details. This is provided with a substantial body structure I which has its upper end forming an internally threaded box I16, this being screw threaded on the pin I3I of the lower jar section 23. Below the box there is a downwardly and cone-shaped taper surface "1 and below this a large hollow space I18 for the battery. A slushing fluid duct I19 extends downwardly through the block and the lower end is illustrated as having an external pin thread The battery assembly and electrical connections designated I85 includes an insulating sleeve I86 which is illustrated as threaded inthe block below the large space I18 and in alignment with the duct I19 and this sleeve extends upwardly other from the block I upwardly around the firing rod.

I illustrate two forms of cartridges, the type presented in Fig. 11 and designated by the numeral 226 which is of a shattering type. This includes the explosive case 22I which has a cylindrical wall 222, a cap 223 with a tapered opening 224. A plug 225 is fitted in this opening and has a ring gasket 226. The base 221 is conical on its lower surface 228 and is provided with a perforation having a percussion cap 229 therein.

into the box I16. There is an annular insulating battery liner I81 which has an outside wall I86, an inside wall I89 forming a snug lit with the sleeve I 86, an annular base I 96 and a cap I9I. The electrodes I92 and I93 of the battery are suitably mounted in the battery chamber and this contains an acid solution. An insulating plug I95 is tapered and fits the inside tapered surface I11. This plug has a tight fit at an annular opening in the cap I9I andon the upper edge of the inner wall I89. The plug has a passage I96 filled with insulating material and is snugly held in place by a collar I91. threaded on the sleeve I86 and exerting a downward thrust on the plug. The electric leads designated I68 and I69 of Fig. 11 extend downwardly into the recess I43 and have connectors I98 at the ends.

I15. Such perforations are filled with electrically insulating material. The electric leads of course are thoroughly insulated. Thus when the various parts are assembled there is an electrical connection from the electrodes of the battery upwardly to the firing pin assembly.

To use one form of shell I make provision of a series of leaf springs 2I6 having their upper ends secured as at 2 in recesses 2I2, these being formed in the bore I22 of the heavy wall structure I2I. These springs are secured at the top and are located below the top of the firing rod, the purpose being to catch the cylindrical part of one type of the shell and allow these to droppast the springs and stack one above an- The explosive indicated at 236 fills the explosive case. Sealing rings 23I and 23I are fitted in annular grooves in the wall of the explosive case, these being for the purpose of having a close fit in the receiving opening 49 of the valve and tohave a relatively close fit in the string of drill pipes so that the cartridge is positively forced downwardly by the fiow of the slushing fiuid. The cartridge has its exterior surfaces checked as indicated at 232 and the whole of the case as well as the plug 225 is made of a composition which on discharge of the explosive shatters into small pieces, these being sufficiently reduced in size so that they may be washed out, through the perforations I46 in the hollow filing rod I45 and through the fiuid discharge ducts I44 in the base I. The cartridge is fired by being forced downwardly by the downward fiow of the slushing fluid through the flap valve I25 and the percussion cap 229 striking the firing pin I48. The two prongs I65 function to center the cartridge as they may engage the conical bottom 228. Of course in-the mounting of the firing pin this may be driven down slightly against the action of the compression spring l6I but it is brought to a stop against the contact plate I61.

The non-disintegrating cartridge designated by the assembly numeral 246, note Figs. 9 and 10,

has a brass or copper cylindrical shell 24I with a composition base 242 secured thereto, this base having a conical bottom surface 243 terminating at a circular opening 244. An electrical nonconducting sleeve 245 is fitted in this recess and snugly fitted to the sleeve is an inverted conducting cup such as of copper 246, this having a cylindrical wall 241, a top 246 and a flared flange or rim 249. A non-conducting plug 256 is fitted in the open mouth of the cup and this has fitted therein a central contact 25I made in the form of a disk with a conducting pin 252 extending upwardly through the plug and into the cup. This center plug contact is connected by a fusible wire 253 connected from the conducting pin to the closed top 248, being preferably connected by solder 254 or the equivalent. The cup.

is filled in the lower portion with a fulminating compound 255 and above this with mealed guncotton or the like 256. The remaining portion of the cartridge is filled with the explosive powder 251. A plastic 258 forms a seal at the bottom of the cup, that is, covering the plug 256, the contact 25I, the flared rim 249 and extending to the coned surface 243 of the bottom 242. The upper end of the cartridge has a composition cap' 266 with a tapered opening 26I in which is in- A manner of operation and functioning of the v cartridge of Figs. 9 and 16, which as above mentioned is specially designed to operate at great depths where the hydraulic pressure is very high, therefore this ;is a stronger cartridge than that of Fig. 11. This cartridge is inserted through the injection valve at the top of the assembly, is carried down by the slushing fluid, forced through the flap valve I25 and strikes the top of the firing rod I45. The firing pin I48 penetrates the plastic composition 258 and forms an electric contact with the central contact 25I. The two piercing prongs I65 of. the firing rod also perforate this plastic and contact the flange 249 which as above mentioned is of conducting material. The firing pin is forced downwardly against the action of the spring I6I, note Fig. 12, bringing the lower end I62 into engagement with the contact plate I61. As above mentioned this contact plate is connected by a wire I69 to the electric battery and by means of an electric lead I69 and the terminal "0, an electrical connection is made to the firing rod adjacent'its upper both of these destroy the cup 246 and ignite the powder or other explosive 251 in the cartridge. Both ends of the cartridge blow out and being made of a composition and the plug 262' also being made of a composition, disintegrate under the action of the explosion. The cup is also destroyed as is the insulating sleeve 245, the central contact 24I--is likewise blown to pieces, the

tical movement. This causes a high'pressur'e onthe fluid trapped in the skirt and causes this to flow inwardly through the ports 85 in the guide pipe 69.

At the instant that the flap valve I closes there is a resistance to the downward fiow of the slushing fluid which is actuated by the pumps at the top of the well and this forces the bypass check valve I5 to open, allowing a discharge of the slushing fluid into the bore of the well outside of the assemuiy. The slushing liquid which is also forced inwardly through the ports 85 also flows outwardly through the check valves. Of course a certain amount of this liquid trapped in the skirt is forced downwardly onthe outside of the head IM and between the shank I66and the collar96. It is not intended that there be a hammer blow between the head IIII and the top shoulder'6'l of the skirt or between the composi tion packing 95 and the upper end of .the heavy walled structure I2I of the lower. part 23 of the jars, however, when these parts occupy the dotted line position ofFig. 1, the composition ring expands and provides a fluid'seal for the tool.

only parts being left-intact of this cartridge is the copper or bronze shell or cylinder 24I.- This drops downwardly after the explosion fitting over the firing pin 245, thefirst shell resting on the bottom block 2. In succeeding explosions ofthe following shells, these hollow sleeves of the cartridges also stack up in the annular space between the firing rod I45 inside of the enlarged bore I22 of the heavy walled structure I2I.

' The action of the explosion with either type of shell is substantially as follows: There is an immediate back pressure on the slushing fluid which normally flows downwardly through the flap valve I25, the spring being normally insuflicient to retain this closed against the pressure of the flowing fluid but the back pressure closes this valve and prevents an upward flow of the slushing fluid. This fluid is therefore under extremely high pressure and is driven downwardly, some of this flowing through the ducts I44 in the block base 'I4I and thence downward- 1y through the tubular space in the battery assembly unit 24. As above mentioned this central duct is formed by the insulating sleeve I86 and the duct I19, the slushing fluid then being driven downwardly through the string of drill pipe 25 to the tool or other equipment to be removed from the well. As this downward discharge of the slushing fluid is at very high pressure, together with the upward reaction, causes an upward in the skirt 63 and the complementary flutes or 75' The purposeof thegrooves I36 in the lower portion of the heavy walled structure I2I is to give sufilcient cross sectional area for the downward flow of the slushing liqu'idfwhen a number of the coppercylinders or shells 2 of the cartridge are stacked one on topof the other ex-' tending upwardly from the blockbase MI. The

various ducts and grooves; are proportioned-to:

give adequate area for the downward discharge of the slushing fluid. fIt' will be seenjtherefore that by the used explosives and by my construction of jars, forcible upward reactions may be developed in regard to the tools or other equipment to be loosened and removed from a well or for any otherpurpose' forwhich a jar v frozen drill pipe or tubing being tubular and the casing also being tubular, the surge of liquid downwardly through the pipe 25 continues through the tubular 'flsh or the casing. This downward surge and flow of the liquid under I high pressure is operative to loosen the material such as sand or other wedging formation which freezes the "fish in the well. Such material is therefore loosened and to a great exte'nt washed out facilitating the removal of the fflsh. Where the equipment is used to-remove casing this'violent downward discharge. of the liquid at" the bottom of the casing is operative to loosen the casing from the well hole and. thus facilitate its further loosening and lifting by the jar.

Various changes may be made in the details of the construction without departing from the spirit, or pe of the invention as defined by the appendedclaims- I I claim: .I

'1. In a device as described the combination of an upper hollow Jar structure anda lo'we'rq complementary tubular Jar structure having a Y telescoping mounting in the. first jar structure,

' cluding a cartridge injection valve with a valve plug having a cartridge receiving opening, means to move the plug from a position having the opening to one side of the axis of the jar structures to alignment therewith and a connection of piping leading from the valve to the first jar structure.

4. In a device as described the combination of an upper hollow jar structure having means for connection to a string of drill pipe at the top and being provided with a depending skirt with an internal collar and a guide pipe centered as to the skirt, the lower tubular guide structure having a shank with a head telescopically mounted in the skirt, a firing pin mounted in the lower structure and positioned to cause the explosion of a cartridge passing downwardly through the guide pipe and the shank to engage the firing pin.

5. In a device as described and claimed in claim 4, the lower jar structure having a connecting means for a lower structural element leading to a tool and passages for the flow of slushing fluid through the shank adjacent the firing pin and communicating with the lower structural element and a check valve operative to close and prevent the upward fiow of slushing fluid on the explosion of a cartridge by the firing pin.

6. In a device as described and claimed in claim 4, the upper jar structure having outlet check valves for the flow of slushing fluid and the lower jar structure having a check valve closeable on the explosion of a cartridge whereby the slushing fluid flowing downwardly through the drill pipe is discharged at the outlet check valves.

'7. In a device as described and claimed in claim 4, the firingv pin being mounted on a firing rod and such rod supported by a base block attached to the lower portion of the lower jar structure, there being ducts for the flow of slushing fluid downwardly through the lower portion of the lower jar structure adapted to transmit a flow of the slushing fluid to a tool or the like connected to the jars.

vide for stacking up of portions of the exploded cartridges. r

10. In a device as described the combination of an upper portion of a jar having means constructed and adapted for connection to a string ofdrill pipe whereby such jar portion may be suspended in a well, the upper jar portion having a skirt with an internal collar and having a guide pipe concentric with the-shell and alignable with the string of drill pipe, a lower jar portion having a tubular heavy wall with a shank extending upwardly therefrom, said shank being slidable.

through 'the collar, a head on the shank within the skirt, such skirt and head having rectilineal guide means, a firing rod having a firing pin located in the lower jar portion with means connecting the firing rod to a lower part of the said heavy wall, there being ducts for the downward flow of slushing fluid in the heavy wall of the lower jar portion with means for communicating the flow of slushing fluid to a tool or the like con- 9. In a device as described and claimed in claim 4, the firing pin being mounted on a firing rod with means connecting such rod to the lower portion of the lower jar structure, electrical contact means connecting with the firing pin for igniting a cartridge which strikes the firing pin, there being an annular space between the firing rod and a wall structure of the lower jar structure to pronected to the lower jar portion and means to insert a cartridge in the suspending drill pipe to be carried downwardly by the flow of the slushing fluid, such downward movement of the cartridge bringing the cartridge in contact with the firing pin.

11. In a device as described and claimed in claim 10, the lower portion of the jar having an upwardly closing check valve above the firing pin constructed and adapted to allow a downward flow of the slushing fluid and downward passage of the cartridge but to prevent upward fiow of slushing fluid under the action of the explosion of the cartridge, the guide pipe being provided with ports communicating with a space between the said skirt, the wash pipe and the head on the shank whereby on the relative telescopic movement of the said shank and head in relation to the skirt and fluid trapped in said skirt is forced inwardly through the said ports to the guide pipe and outwardly reacting check valves in the upper portion of the jar operative to open for the continued flow of the slushing fluid.

12. In a device as described, the combination of tubular telescopically connected upper and lower jar structures constructed and adapted for suspending in a well and for connection to a tool,

.such jar structures, having ducts and spaces to be filled with a liquid and means to explode an explosive in the lower jar structure and thereby exert an expulsive force on the liquid.

13. In adevice as described and claimed in claim 12, an upwardly reacting check valve in the lower jar structure constructed and adapted for a downward flow of liquid to fill the-jar structures and adapted to form a closure against the upward fiow of the liquid under the pressure of the explosion.

14. In a device as described the'combination of telescopically arranged tubular upper and lower jar structures, the upper structure having means for suspension by a pipe in the well and the lower structure having means for a tubular connection to a tool, means to flow a liquid downwardly through the jar structures to a tool, means to discharge an explosive in the lower jar structure and a pressure reacting means to prevent upward flow of the liquid in the lower jar structure under the pressure developed by the explosion whereby the liquid is forced downwardly towards the tool.

15.'In a. device as described, an upper and a 'lower tubular jar structure having a telescopic structure having means for a tubular connection to a tool, a firing rodha-ving a firing pin located in the lower structure, the pin pointing upwardly, a cartridge having an explosive therein and having'a confining means therefor which shatters on explosion, there being ducts and passages for the downward fiow of a liquid whereby a liquid forced downwardly through the tubular jars discharges the shattered portion of the cartridge.

16. In adevice as described and claimed in claiml5, an electric battery with a supporting connection from one of the jar structures and an electrical connection to contacts, one of which being the firing pin, the cartridge having an electrical igniting element and electrical conductors to close a circuit on engaging the contacts of the firing pin.

17. In a device as described a cartridge having a composition wall constructed and adapted to shatter into small pieces, an explosive therein, a percussion cap, a guide means to guide the cartridge in a vertical drop, a firing pin positioned to engage the percussion cap whereby the cartridge may be exploded, there being passages for the downward fiow of a liquid and the discharge with the liquid of the shattered cartridge.

18. In a device as described, the combination of'a cartridge having a shell with destructible base and cap connected thereto, an inverted conducting cup mounted in the base and having a rim forming an electric conductor, a central contact with a conducting element extending into the cup, the cup containing an igniting explosive and the shell containing the main explosive, and a firing pin assembly including a central pin and at least one piercing prong with electrical connections to the central pin and the prongs whereby on contact of the central pin and prongs with the central contact and the rim of the cup, an electric circuit is completed as'to the said cup and the igniting explosive therein.

19. In a well tool having a structure to engage a tool to be pulled and a pulling structure extending to the upper part of the well, there being an intermediate chamber structure adapted to contain a liquid, said chamber having means to receive an explosive, means providing for the explosion of the explosive, there being a passage for the downfiow of liquid from the chamber due to the expulsion of liquid by the explosive action whereby such liquid may loosen the tool to be pulled'from the well.

20. In a 'well tool having a lower drill tube to engage a tool to be pulled from a well, an upper drill tube leading to the top of the well for the pulling action, said tubes being adapted for the downward fiow of liquid, a chamber structure intermediate the upper and lower tubes and through which the liquid flows, said chamber having means for the introduction of an explosive. means to ignite such explosive, means to restrain the upward fiow of the liquid due to the explosive gasesof an explosion whereby the liquid is directed mainly downwardly through the lower drill tube and adapted to exert a force to loosen the tool to be removed from the well.

21. In a fishing tool having a lower tube con structed and adapted for attaching to a fish to be removed from a well, an upper tube adapted for lowering the-fishing tool and for pulling the same upwardly, telescopic chamber structures forming a connection between the lower and upper tubes, the said tubes and the chamber structures being adapted for the downward fiow of a slushing liquid, said liquid being adapted to convey an explosive downwardly into the said chamber, means to ignite the explosive therein, means to restrain the upward fiow of liquid due to the gases produced in the explosion, the expulsive force of the explosion being adapted to discharge liquid downwardly under high pressure and velocity through the lower tubular structure operative to loosen the fish from the well.

-22 In a fishing tool having a lower tube constructed and adapted for attachment to a fish to be removed from a well, an upper tube for lowering the fishing tool and pulling the-same upwardly, an upper chamber structure connected to the upper tube, a lower chamber structure connected to the lower tube, means forming a telescopic. connection between said chambers, the tubes and the said chambers being adapted for the downward flow of a slushing liquid and to convey an explosive charge to the lower chamber,

means in the lower chamber to explode the said charge, a check means restraining the upward surge of the trapped liquid from the lower chamber whereby liquid in the lower chamber and in the lower tube is forced downwardly by the action of the explosive to thereby loosen a fish, aliquid outlet operatively connected to the upper chamber whereby on the telescopic action of the chamber connections and the stoppage of the downward fiow of the slushing liquid, such liquid is forced outwardly into the well through theliquid outlet.

23. In the method of recovering a fish from a well which includes effecting a connection between a drill pipe and a fish, the pipe having liquid therein, exploding an explosive in the pipe to loosen the fish and withdrawing the pipe and fish from the well.

24. In the method of recovering a fish from a well which includes efiecting a connection between a. drill pipe and a fish, the pipe having liq.- uid therein, exploding an explosive in the pipe closely above the fish to loosen the fish and withdrawing the pipe and fish from the well.

25. In the method of recovering a fish from a well which includes effecting a, connection between a drill pipe and a fish, the pipe having liquid therein, exploding an explosive in the pipe closely above the fish to loosen the fish causing the explosive to be effective to force liquid downwardly through the drill pipe by resisting upward flow through the drill pipe above the locality of the explosion and withdrawing the pipe and fish from the well.

26. The method of recovering a fish from a well which includes effecting a connection between 'a drill pipe and a fishand having liquid in the pipe, conveying an explosive downwardly through the liquid by a free gravity descent, exploding such explosive in the drill pipe closely above the fish causing the explosive to be effective to force liquid downwardly'through the drill pipe by resisting upward flow through the drill pipe above the locality oi the explosion to loosen the fish and withdrawing the pipe and fish from the well.

EUGENE W. DODGE.