BACKGROUND OF THE INVENTION The production of hydrocarbons often requires borehole extending thousands of feet down into the earth and that the hydrocarbons contained within a payzone be con ducted into the borehole and up to the surface of the eart where the hydrocarbons are gathered. Most hydrocarbon pro ducing wells require that a pumpjack be installed on th surface of the ground for reciprocating a string of sucke rod that extends downhole through the borehole to a downhol pump, so that the downhole pump lifts the formation fluid u through a tubing string to the surface of the earth. Th downhole pump art is quite extensive and many clever engi neers have spent a lifetime studying and working on downhol pumps of the type that are reciprocated bv a pumpjack unit. Various means for holding the pump apparatus down hole while the sucker rod string reciprocates part of th pump are known to those skilled in the art, and usually tak the form of a seating nipple which is attached to the tubin string, and a pump hold-down which is sealingly supported i a removable manner in the seating nipple. Thus, the ro string can also be used to lift the pump hold-down from the seating nipple, thereby enabling repairs to be effected on the pump. It is well known that some pumps have a traveling barrel, while other pumps have a traveling plunger. There is no problem pulling a pump with the sucker rod string so long as it is not stuck downhole in the pump cavity or seat¬ ing nipple. All that is required is time and money for the work-over rig and crew. Some geological formations produce sand and other debris along with the production fluid. The sand and debris sometime become lodged between the seating nipple and the pump hold-down. When it comes time to pull the downhole pump, the sand and debris cause the pump to become stuck downhole, and the sucker rod string will break or part be¬ fore it will lift the stuck downhole pump from the pump cav-

ity of the borehole. A sucker rod string costs a lot of money, and can be ruined if it is overstressed and broken.

A stuck pump necessitates pulling the tubing string along with the rod string in order to replace the downhole pump. It is very expensive to pull the entire tubing string from a borehole, and in some instances where the tubing string is 8,000 to 10,000 feet long, the cost can amount to several thousand dollars. This is called "pulling a wet string", or a "stripping job", and is a detestable job for the roughnecks to endure, especially in the winter.

Many wells produce sour gas and salt water along with the crude oil. The pumps in these wells are stuck so often that they are almost always stripped of the rod string and tubing string whenever there is trouble with the down- hole pump. The cost often causes the owner to shut-in a marginal well rather than endure the recurring cost of stripping the wet string several times a year.

The present invention provides method and apparatus by which a stuck downhole pump can be unseated and subse- quently pulled from the borehole in a manner which avoids parting or over stressing the sucker rods, and which avoids the necessity of pulling the entire tubing string. This greatly reduces the cost of operation and allows a marginal well to be produced so that the hydrocarbons are made avail¬ able to the public for many additional years.

The present invention is especially useful in con¬ junction with fiberglass sucker rod strings. Fiberglass rod strings are used predominantly where highly corrosive well fluids are encountered because the string is relatively in- ert and resists chemical reaction with the well fluids; however, the string has limited tensile properties and is easily parted. It follows that the present invention finds great utility in conjunction with a fiberglass rod string for a multitude of reasons, including the before mentioned ones, and others that will occur to those skilled in the art as this disclosure is more fully digested. This patent ap¬ plication is directed to one who is skilled in the art and

such a person will understand the specifics of a downhol production pump, as for example an API RWTC type pump, AP RWBC type pump, or a "tubing pump" of the type having a pum barrel incorporated as an integral part of the tubin string, with the pump plunger being lowered into the tubin on the bottom of the rod string. These production pumps ar reciprocated by a rod string; and are provided with a hold down of sorts which is received within a seating nipple o some arbitrary known design.

SUMMARY OF THE INVENTION

The present invention broadly relates to both metho and apparatus for unsticking a downhole production pump fro its seating cavity by pushing the pump in an uphole direc tio and thereby forcing the pump to become unseated fro the seating cavity.

The present invention broadly sets forth both meth od and apparatus for unsticking a downhole production pum located at the lower end of a tubing string from its seatin nipple by pushing the pump hold-down in an uphole directio and thereby forcing the pump to become unseated from th seating nipple. This enables the downhole pump to be easil removed from the borehole by pulling the pump with the suck er rod string after the pump is unstuck according to th teachings of the present invention.

In its more specific form, the present invention i used in a fluid producing well having a downhole pump assem bly located at the lower end of a tubing string for produc ing fluid from a payzone wherein some parts of the pump ar affixed to a hold-down means and the hold-down means is tel- escopingly received within a support means, as for example a seating nipple. The tubing string is supported at the surface of the earth by known means and lowered in a down- hole direction in order to unstick the downhole pump. Means associated with the pump hold-down engage the borehole, as for example the bottom of the borehole, and thereby apply an uphole force or thrust on the hold-down which is equal to

the amount of weight that is transferred from the surface equipment, into the tubing string, and into the wellbore. This action provides an upthrust on the hold-down which can be progressively increased to whatever value is required to force the pump to become unseated. The tubing string is then returned to its normal attached position at the well¬ head, and the unstuck downhole pump can thereafter be easily pulled, for example by using the sucker rod string, thereby leaving the tubing string in the borehole and avoiding over stressing and parting of the sucker rod string.

More specifically, the present invention provides a combination with a downhole pump assembly of an apparatus by which the pump hold-down is pushed in an uphole direction and thereby forces the hold-down to become unseated from a seating nipple. The apparatus includes an adaptor located at the lower end of the pump hold-down that extends downhole away from the seating nipple. Means associated with the downhole equipment are connected to engage the borehole and apply an upward force on the adaptor in response to the tub- ing string being lowered downhole. This action unseats the hold-down from the seating nipple and moves the pump uphole respective to the tubing string, thereby unsticking the pump and allowing it to be retrieved from the wellbore without exceeding the structural integrity of the rod string.

The present invention also can be used to unstick a pump that has a broken rod string by fishing the part of the string that is connected to the pump and thereafter unstick¬ ing the pump in one of the above described manners.

A primary object of the present invention is the provision of a method of unsticking a downhole pump located at the bottom of a borehole by forcing the pump uphole in response to lowering the tubing string.

Another object of the present invention is the pro¬ vision of apparatus by which a production pump located down- hole in a borehole can be unstuck by lowering the tubing string, and consequently upthrusting the pump in response to

the downward movement of the tubing string, thereby un sticking the downhole pump.

A further object of this invention is the provisio of apparatus connected to a seating nipple and a pump hold- down by which downward movement of a tubing string causes upward movement of the pump hold-down thereby forcing the pump hold-down from the seating nipple.

A still further object of this invention is the provision of a telescoping apparatus having a lower marginal end for engaging the bottom of the borehole and an upper marginal end connected to a seating nipple: with a pump hold-down device having an extension adapted to abuttingly engage the lower marginal end of the telescoping apparatus and to thereby push the pump in an uphole direction respec¬ tive to the seating nipple in response to downward movement of the tubing string.

An additional object of this invention is the provi¬ sion of method and apparatus by which a downhole production pump can be unstuck by moving the pump uphole respective to the seating nipple from a location below the downhole pump. Another and still further object of the invention is the provision of method and apparatus for removing a stuck downhole production pump from the lower end of a hydrocarbon producing borehole by lowering the tubing string downhole until a telescoping extension device encounters the borehole and pushes the pump uphole respective to its seat in re¬ sponse to the downward movement of the tubing string.

These and various other objects and advantages of the invention will become readily apparent to those skilled in the art upon reading the following detailed description and claims and by referring to the accompanying drawings.

The above objects are attained in accordance with the present invention by the provision of a method for use with apparatus fabricated in a manner substantially as de¬ scribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a part diagrammatical, part schematical, part cross-sectional, side view of a section of the earth showing a prior art hydrocarbon producing apparatus ;

Figure 2 is a longitudinal, part diagrammatical, part schematical, part cross-sectional, broken, side eleva- tional representation of apparatus made in accordance with the present invention:

Figure 3 is similar to Figure 2 and shows the appa- ratus of Figure 2 in an alternate configuration;

Figure 4 is a partly disassembled, part cross-sec¬ tional, longitudinal, broken, side elevational view of some of the apparatus disclosed in Figures 2 and 3 ;

Figure 5 is a diagrammatical, part cross-sectional, broken, side elevational view that is representative of part of the apparatus disclosed in Figures 2-4;

Figure 6 is a disassembled, part cross-sectional, side view showing some of the present invention in full lines and certain prior art apparatus is shown in dot-dash; Figure 7 is an enlarged, cross-sectional view taken along line 7-7 of Figure 6;

Figure 8 is an enlarged, cross-sectional view taken along line 8-8 of Figure 6;

Figure 9 is a broken, part cross-sectional, perspec¬ tive view of apparatus made in accordance with the present invention; and,

Figure 10 is a further disassembled, elevational view of part of the apparatus disclosed in Figure 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 discloses a prior art oil well production system 10 having the usual pumpjack unit 11 supported above the surface of the ground for reciprocating the polished rod of a string 12 of sucker rod. The sucker rod string 12 ex¬ tends downhole through a wellhead 14 and through a cased

borehole 15. A production tubing string 16 is concentrical ly arranged within casing 15, leaving annulus 17 therebe tween.

Deep, down within the borehole is a downhole produc tion pump 18, that can take on any number of differen forms, and particularly includes a pump device having traveling barrel, or a pump device having a traveling plung er, as well as a pump device that can be entirely remove from the tubing string by manipulation of the sucker ro string in a manner known to those skilled in the art.

The last tubing joint 19 of the tubing string 16 i usually connected to a collar 20, which in turn is usuall connected to an ordinary seating nipple 21. A collar 2 connects the seating nipple to a perforated joint 23. Col lar 24 connects the perforated joint to a mud anchor 26 tha terminates in a bull plug or the like at the lower termina end 27. A gas anchor 25 has a hollow interior which is con nected to the before mentioned pump 18 and communicates wit the intake of the production pump by means of a pump hold down. Numeral 28 indicates borehole structure, particularl the bottom of the borehole.

Comprehension of the elementary prior art hydrocar bon producing system set forth in Figure 1 is essential fo an understanding of the present invention. Those skilled i the art to which this patent application is directed full comprehend all of the above prior art recitation and will therefore be able to fully comprehend and appreciate the following novel method and apparatus.

Figures 2 through 10 set forth method and apparatus by which a downhole production pump 18 can be unstuck by pushing the pump uphole from a location below the downhole pump. As particularly seen in Figures 2 and 3, together with other figures of the drawings, the pump has a plunger 29 which is reciprocated by sucker rod 12. The plunger is shown as being reciprocatingly received within the barrel of a downhole pump 18 in the usual manner. The pump hold-down, generally indicated by numeral 32, includes the usual no-go

30 shown in the form of a circumferentially extending en¬ largement formed thereon which is made of a greater diam¬ eter than the seat 31 formed on the seating nipple 21. The pump hold-down 32 has the usual seals and opposed threaded ends formed thereon. The pump hold-down and seating nipple take on many different forms and are well known to those skilled in the art.

Numeral 33 indicates the lower end of the hold-down 32, while numeral 34 illustrates a novel adaptor, which pre- ferably is in the form of a heavy, hollow, elongated, hexa¬ gon shaped bar that is threaded at one end thereof so as to be received by lower end 33 of the pump hold-down 32: and, adaptor 34 is threaded at the other end thereof for receiv¬ ing the upper marginal terminal end of a prior art gas an¬ chor 25. Accordingly, the assembly just described in con¬ junction with Figure 2 is also seen on the left hand side of Figure 4; and, commencing at the top of the left hand side of the Figure 4, will be seen to include a sucker rod string 12, a pump barrel 18, a no-go 30, a hold-down 32, a lower end 33 of the hold-down, and a heavy, hollow, hexagon bar that forms an adaptor 34 having a lower terminal end 35 which is made in the form of a circumferentially extending shoulder. The shoulder forms an abutment for abuttingly en¬ gaging an upper annular seat or shoulder 36 of a novel tele¬ scoping sleeve assembly 123 for reasons that will become more apparent later on in this disclosure. The hollow, per¬ forated gas anchor 25 preferably is affixed to the lower end of the adaptor extension 34, leaving shoulder 35 confronting shoulder 36 of sleeve assembly 123. The novel adaptor extension 34 of this invention is substituted for the usual prior art short, hollow, coupling having thread configurations at each opposed end thereof that normally connects the gas anchor to the lower end of the pump hold-down 32.

It is within the comprehension of this invention to fabricate the pump hold-down, extension 34, and gas anchor 25 in any number of different units that can be subdivided

and thereby facilitate fabrication and assembly thereof.

Still looking at Figure 4, together with other fig ures of the drawings, the apparatus on the right hand side commencing with the last tubing joint 19, is seen to be con nected to seating nipple 21 which in turn is connected t the novel telescoping sleeve assembly 123 which is comprise of an upper fixed tubing extension 37 arranged to telescop ingly receive a lower marginal length of a slidable pum upthrust member 38 therewithin. The abutment 35 is there fore normally spaced from and confronts abutment 36 forme at the upper terminal end of the slidable pump upthrust mem ber 38, which is connected to a mud anchor 26.

In Figures 2 and 3, collar 39 has an upper shoulde

40 formed thereon that abuttingly engages a lower shoulde

41 that forms the lower terminal end of the tubing extensio that forms part of sleeve assembly 123. A safety catch 4 limits downward motion of the telescoping upthrust member 38 of sleeve assembly 123 to prevent the lower marginal end o the sleeve assembly from separating from the upper marginal end thereof. As best seen in Figures 4 and 6, numeral 43 indicates the lower terminal end of the gas anchor which is spaced from the lower terminal end 127 of the mud anchor 26. Outlet ports 44 are formed into the upper marginal end of the fixed tubing extension of telescoping member 123. These ports allow exit of fluid from tubing string 16 after the pump hold-down 32 is forced upward and out of the seating nipple 21. A product inlet port 145 of Figure 9 serves as an inlet for well fluid to enter member 38 at a location above the perforations of gas anchor 25. In Figure 6, an elongated slot 45 forms part of the safety catch 42.

As seen in Figure 7, wrench flats 46 form the exten¬ sion member or bar 34 into a hexagon configuration, although many other geometrical configurations can be used where wrench flats are not desired. Numeral 47 indicates a lon¬ gitudinally extending axial passageway extending through the hollow, hexagon bar 34 for connecting gas anchor 25 (Figures 2-4) to the pump hold-down at 32.

In Figures 6 and 8 , a guide pin 48 is attached by head 49 to upthrust member 38, with the pin extending through the before mentioned slot 45. Annulus 50 is formed between gas anchor 25 and upthrust member 38. Numeral 51 indicates in inner surface of upthrust member 38 while num¬ eral 52 indicates the inner surface of the fixed tubing ex¬ tension and numeral 54 indicates the longitudinal axial pas¬ sageway formed through the gas anchor 25. In Figure 10, the threaded end of the pump hold-down is indicated by numeral 55 while numeral 33 indicates the upper threaded end of the adaptor 34.

In operation, the apparatus of the present invention is made up in combination with any number of different down- hole pumps of various designs, with the adaptor extension 34 being made into a suitable configuration for adapting or connecting the gas anchor to whatever hold-down 32 that may be used, with collar 22 of the fixed tubing extension 37 being made into a configuration that is readily adapted to the seating nipple 21 that may 'be selected for use in sup- porting the downhole pump 18. The apparatus on the left hand side of Figure 9 is run downhole on the end of the tub¬ ing string and is properly positioned and supported within the borehole using prior art techniques. Next, the appara¬ tus seen on the right hand side of Figure 9 is run downhole on the end of the pump assembly, or part of the pump assem¬ bly that is attached to the rod string, and properly posi¬ tioned in and through the seating nipple. In order to achieve this simple assembly of the combination disclosed herein, it is necessary that field personnel, skilled in the art, make certain that the abutment 35 located at the lower end of adaptor 34 be properly spaced respective to the upper shoulder 36 of the pump upthrust support 38. Further, it is essential that safety catch 42 be arranged with pin 48 posi¬ tioned near the lower extremity of slot 45. Moreover, stop member 39 must be properly spaced below shoulder 41 a suffi¬ cient distance that will not interfere with the operative engagement of annular shoulders 35 and 36. Those skilled in

the art, having digested this disclosure, will appreciat that different hold-downs and seating nipples can advantage ously be employed herein. The invention need not be limite for use in conjunction with a pump operated by a rod strin for there are hydraulically actuated pumps of both the fre and fixed types that can be used to great advantage in con junction with the teachings of this invention. The best mod of operation is considered to be in conjunction with a down- hole pump that is reciprocated by a rod string, and Appli- cant has reduced this embodiment of the invention to prac¬ tice.

In the preferred embodiment of the invention as dis¬ closed in Figures 9 and 10, adaptor 34 connects gas anchor 25 to whatever hold-down 32 may be used, with collar 22 of the fixed tubing extension 37 being made into a configura¬ tion that is readily adapted to the seating nipple 21 that may be used for supporting the hold-down of the downhole pump 18. This necessitates that the distances LI, L2 , and L3 of Figure 2 be carefully considered to assure that the relative operational range admit a proper range of travel of the components so that the final result provides a structure that enables the practice of the method of this invention.

With the apparatus of the present invention install¬ ed downhole in a borehole in combination with the downhole pump and other subsurface equipment, the time will eventual¬ ly arrive when the downhole pump will become worn and will fail, and therefore must be retrieved for repair or replace¬ ment. At that time, an ordinary pulling unit will disengage the polish rod from the pumpjack horsehead and attempt to pull the pump or the appropriate parts of the pump 18 up through the tubing string by means of the sucker rod string 12. Often the pump will be stuck and the rod string can be injured when undue tension is placed thereon. At this time, according to this invention, it is necessary, as seen in Figure 5, to latch onto the tubing string by means of clamp¬ ing and lifting apparatus 46', which is supported at 146 A and to gently lower the tubing string downhole a few feet

until the lowermost end 127 (Figures 2 and 3) of the mud anchor rests against the bottom 28 of the borehole, thereby pushing the pump upthrust member 38 uphole until shoulder 36 is brought into engagement with shoulder 35 at the terminal end of the adaptor 34; whereupon member 38 engages adaptor 34 and pushes the pump hold-down 32 uphole respective to the seating nipple 21. This new and novel method unsticks the pump in a patentable manner heretofore unknown and there¬ after permits the pump to be safely pulled on at 245 by using the rod string 12. This action pushes the pump uphole respective to the fixed tubing extension 37 by means of the upthrust member 38 as a result of the annular shoulder or face 36 pushing uphole while in engagement with the terminal end 35 of adaptor 34. This action applies an upward force on the adaptor 34 which can be progressively increased to an enormous value that often is far in excess of the tensile strength of the rod string. The upthrust is progressively increased until it overcomes the force with which the pump is stuck in the pump cavity and thereby pushes the pump hold-down 32 uphole respective to the seating nipple 21, which unsticks the pump and thereafter permits the pump to be pulled by the rod string. Accordingly, the tubing is next reposition and reattached to the wellhead and there¬ after the rod string can be used to pull the pump in a con¬ ventional and inexpensive manner now that the downhole pump has been unstuck and the only tension force left to contend with is the weight of the rod string and the pump.

A specific application of the present method and ap¬ paratus is as follows : A 5,000 foot well has a 2 and 3/8 inch tubing string

(4.7 lbs/ft) and a 3/4 inch grade C rod string {tensile strength 28,000 lbs; weight 1.8 lb/ft) with a pump which is 2 inches by 1 and 1/4 inch by 16 feet RHBC (API).

The pump is stuck and the pulling unit cannot unseat the pump without exceeding the tensile strength of the suck¬ er rod string. It is assumed that the unseating apparatus of the present invention has previously been placed in oper-

ative position downhole in the borehole in combination wit the other necessary subsurface equipment.

The rod string weighs 9,000 lbs. (5000 X 1.8). Th hydrostatic load on the effective cross-sectional area o the pump hold-down is 6494 lbs. (the cross-sectional area o the hold-down is 2.4052 sq. in.). The pressure gradient o the tubing fluid is 0.54 psi/ft. The pressure on the seat ing nipple is 2700 psi. (2700 X 2.4052 = 6494 lbs.). Thes figures are approximate. Friction hold-down of the seatin nipple on the hold-down of the pump requires 1000 pound pull to be overcome. Friction between rods and tubing a the rods are pulled uphole is estimated to be 1000 pounds, assuming no paraffin build up. Accordingly, the pullin unit must pull the following: rod weight 9000 lbs., hydro¬ static load 6494 lbs., seating nipple friction 1000 lbs., rod/tubing friction 1000 lbs. Therefore, the total pulling force required for release of the pump is 17,494 lbs. of upward pull, which also is the required rod tension. How¬ ever, the pump has accumulated scale, sand, and other debris causing the pump to bind and to become stuck in its seat. The maximum allowable rod pull is exerted by the pulling unit; however, the pump does not move and any additional force will stretch the rod string and continued stress will cause the string to part. Under these conditions the pump cannot be pulled from the pump cavity, but with the present invention it is possible to push the pump uphole with an available force of enormous magnitude.

The weight of the tubing is 25,180 lbs. Added to this is the weight of the fluid not acting as a hydrostatic head on the cross-sectional area of the pump. Lowering the tubing and lifting or pushing the pump hold-down uphole in accordance with the present invention makes available more than 25,180 lbs. acting as an upward force on the stuck pump before any tension is exerted on the rod string. The usable or actual upward pull on the pump by pulling the maximum allowable pull on the top rod is about 10,000 lbs (maximum rod tension of 28,000 lbs. minus resisting loads of 17,494

lbs.). Therefore, more than 35,180 lbs. of force are now available to act directly to move the pump uphole respective to the seating nipple to thereby achieve unseating of the stuck pump in an unexpected, new, different, and heretofore unknown manner.

The present invention is intended to be used with pumps which are built as a unit; that is, barrel, plunger and hold-down are run together on the rod and inserted into the seating nipple. The present invention is easily adapted to a downhole pump where the barrel is run as part of the string and only the plunger is run on the rod. The present invention further is advantageously used where the plunger is lowered to catch the standing valve/hold-down assembly.

The present invention provides method and apparatus that can advantageously be used for any downhole pump that incorporates some form of seating nipple and some form of . pump hold-down where the pump hold-down or the seating nip¬ ple or other parts of the pump are liable to cause the pump to get stuck downhole in a borehole.