US2194154A - Deep well pump - Google Patents

Description

March 19, 1940. B. H. SCOTT DEEP WELL PUMP Filed July 22, 1935 2 Sheets-Sheet l INVENTOR'. fi'rward ff 564/7 Z'ORNEY.

Patented Mar. 19, 1940 UNITED STATES DEEP WELL PUMP Bernard H. Scott,Glendale, Calif.,.assignor to Alfred Barstow, Alhambra, Calif.

Application July 22, 1935, Serial No. 32,554

8Claims. (o1. lea-194) possible to produce the entire available output.

This invention-relates to deep well pumps, particularly to pumps used in producing oil wells, and has as its broad object to improve the efficiency and reliability of such pumps.

' In pumping oil from wells the sucker rod syste is in general and extensive use and the various types of pumps used in connection therewith are fundamentally the same. They consist of a smoothly finished cylinder commonly termed the working barrel attached to the string of tubing and positioned near the bottom of the hole. Within this working barrel is a hollow or cylindrical plunger, attached to the lower end of the string of sucker rods. Th plunger is reciprocated by applying reciprocatory movement to the upper end of the rod string, above the surface of the ground. At the bottom of the working barrel is a check valve, commonly of the ball and seat type, permitting fluid to pass from the well into the barrel but preventing its return. This is called the standing valve. A similar check valve called the traveling valve is attached to the top of the plunger, to permit fluid to pass from the plunger into the tubing above it but to prevent its return. In a well several thousand feet in depth, the weight of the sucker rod string will be great, as also will the Weight of the fluid column which must be moved upward at each stroke. Thus on every up stroke the rod string will stretch and on every down stroke it will shorten, which results in the effective stroke at the plunger being materially less than the stroke appliedto the upper end of rod string. Further at the beginning of the up stroke when the weight of the column of fluid (in the tubing) istaken from the tubing string by the plunger, the tubing string will decrease in length. Conversely, at the beginning of the down strokewhen this weight is returned to the tubing from the plunger, the tubing string will stretch. Thus there is the stretch of the rod string and tubing string both effective at the same'time to reduce the effective stroke of the plunger. It can be readily shown that in a well having the pump at a. depth of 6,000 feet, with a'standard 2 diameter pump, standard sucker rod equipment and producing an average grade of oil, that this loss of stroke may be as much as 26". Thus with a stroke of 42" at the polished rod above the ground, the effective stroke at the pump will be only about 16'.

To obviate in part the aforementioned difiiculties, pumps having smaller diameter plungers have been used. Due to the smaller weight, due to the smaller diameter of the column of fluid being raised, the stretch in the rods and. tubing is reduced. Also, the rod string may be a little lighter still further reducing the stretch in it. However, the capacity of a small diameter pump is'low and if a well is a good producer it is im- Various mechanical difliculties result from this continual tensing and relaxing of the rods and tubing, especially the former. Chief among these are ,whip and early crystallization of the threaded connections in the sucker rods. The latter leads of course to breakage, resulting in an enforced shut-down of the well and an expensive job of replacement.

' Accordingly, the objects of this invention may be said to include: The provision of a pump in which the stretch of the rod string and tubing is reduced, resulting in: Increased efiiciency and reduced rod breakage; and which has increased capacity.

In the drawings:

Fig. 1 is a longitudinal elevation of my invention disposed within a Well casing illustrated in section;

Fig. 2 is'a sectional view of the top part of Fig. 1;

Fig- 3 is a sectional view of the middle part of Fig. 1 continuing the'showing of the elements of, my invention illustrated in Fig. 2;

Fig. 4 is a view similar to Figs. 2 and 3 of the lower part of the device shown in Fig. 1. v

Fig. 5 is a schematic showing of the pump assembly.

The usual well casing is indicated by 5 and is supported at its upper end by a pumping head 6 3 of any preferred form. Branch pipes I serve to convey any gas the well may be producing to wherever desired. The oil that is being pumped is discharged through a pipe 8, and a polished rod 9 passes through a stuffing box NJ at the top of the head. This is the common form of pumping head and as it forms no part of the invention, it will not be further described.

Referring again to casing 5, this-penetrates the oil bearing strata H, the portion therein having openings or perforations I2 to allow the oil to enter. The usual shoe I3 is provided at the lower end of the casing, while a cement ring I4 serves to prevent incursion of water from above into the oil sands. Within casing and also supportedfroin the pumping head 6 is the tubing string H3 at the lower end of which is a pump l of standard construction. This will now be briefly described.

A short section of pipe or'tubing I8 is interiorly threaded at each end and has a special collar i9 and 20 screwed into it. Each of these has an interior annular shoulder between which is clamped the working barrel 2!. The upper collar it serves to attach the pump to the end of tubing I6, while the lower collar 20 has a. mandrel 22 secured to it. This mandrel has a taper seat 23 at its upper end which supports the standing valve 24. This is shown as having a Garbutt rod 25. Slidable within working barrel 2! is the hollow cylindrical plunger 26, which has the traveling valve structure 21 at its upper end. This also serves to attach the plunger to the end of the sucker rod string 28.

Secured in the tubing string is at some point above pump 17, preferably slightly less than half way to the surface, is a second pump 30. An outer casing 3!, similar to pipe I8, is secured be tween upper and lower collars 32 and 33, these clamping a working barrel 35 between them as before. Lower collar 33 has tubing string I6 threadedly secured in it, while the upper collar 32 has a short section of tubing 36, provided with openings 3'1, secured to it. Collar 33 is attached to the upper end of short section 36 and is in turn threadedly secured to the tubing string it, which is continuous from that point to the pumping head 6. A taper seat 39 is formed in collar 38, for a purpose to be presently set forth. Slidable within working barrel 35 is a hollow cylindrical plunger 49. This has a check valve structure M at its lower end, so arranged as to pass fluid from the tubing below into the plunger, but to prevent reverse flow. Sucker rods 28 are attached to the bottom of the valve structure, serving to tie plungers 2B and All together and cause simultaneous and equal movement.

A piston rod or plunger stem Mi is attached to the upper end of plunger MI, by means of a threaded bushing 43. A check valve structure id is attached to the upper end of plunger stem 42 and allows fluid to pass upward through the stem into the tubing string. Valve structure 44 is similar to the traveling valve 21 on the lower plunger. and constitutes an upper, or second traveling valve. Supported in taper seat 39 is a hollow plug 45 having a conical portion 46 adapted to form a fluid-tight joint therewith anda downwardly extended threaded portion 47. Secured to the latter is a short piece of tube 48, interiorly threaded at its lower end to receive a second hollow plug 49. These plugs have bores of slightly greater diameter than the plunger stem and have clamped between them a packing sleeve 59, the interior of which is a close sliding fit on stem 42 substantially fluid-tight. The arrangement of this packing sleeve is similar to that of the working barrels. A sucker rod string 5! is attached to valve structure 44 in the usual way and extends to the pumping head 6, terminating at the polished rod 9, which is attached to the walking beam, or any preferred mechanism for imparting vertical movement to the rod string.

Ports 3'! permit the unrestricted passage of fluid into and out of the tubing between plunger 48 and plug 45 in response to suction and pressure therebetween caused by the reciprocation of the plunger.

The invention may be, perhaps, visualized as comprising the insertion in a string of tubing terminating in standard pump, of a second pump 38 of novel form approximately midway between the lower pump and the point of fluid delivery.

The advantages of this novel arrangement may be briefly summarized as follows: With the rod string moving upward, the total weight being lifted will be, in addition to the rods, plungers, etc., the weight of a column of fluid of the crosssection of the lower plunger 26 and of a height equal to the distance between the upper and lower plungers, plus that of a column of fluid of the cross-section of the plunger stem 42 and of a height to the distance from the top of stem 42 to the point of delivery. Thus by the insertion of the second pump the weight lifted on the up stroke will be less by that of the fluid column whose cross-sectional area is equal to the difference.

Upon the commencement of the down stroke, the weight of the string of sucker rods, plus the hydrostatic weight of the oil in the tubing string multiplied by the cross-sectional area of the lower plunger, is exerted downwardly to unseat the traveling valves 21 and 44 in the lower and upper plungers respectively. The fluid in the lower working barrel 2! beneath the downwardly moving lower plunger 25 is trapped by the closure of valve 24 and hence must pass into the tubing through valve 2'! and then on into the upper plunger through valve 4! and thence through valve M into the tubing above. Thus, on the upstroke, the volume of fluid discharged will equal the cross-sectional area of the plunger stem 42 times the length of the stroke, and this will be fluid from the tubing above seat 39. On the down stroke, fluid equal in volume to the cross-sectional area of the lower plunger 26 times the length of stroke will be discharged into this space as just described. The length 01 stroke being the same in each case, and the cross-section of the plunger being greater than that of the plunger stem, fluid will also be discharged from the tubing on the down stroke equal in volume to the difference in cross-sectional areas of the plunger 26 and plunger stem 42 times the length of the stroke.

Furthermore, due to the reduced area of the moving fluid column in the tubing above the upper pump, there is more weight remaining on the tubing which decreases the amount by which it moves upward. Also, as this fluid column above the upper pump continues to move on the downstroke, there is less weight applied to the tubing, which reduces the amount it stretches, or moves downward.

It can be shown mathematically that using standard sized parts at commonly pumped depths that the efiiciency of a pumping system arranged in accordance with this invention is of the order of 63 per cent, as compared to as low as 36 per cent for a single pump.

It will be plain from an inspection of the drawin gs that the entire sucker rod assembly, together with standing valve 24. is readily removable from the tubing. The opening through the taper seat 39 being large enough to permit both plungers to pass it. As the rod assembly is raised, bushing 43 engages the bottom of hollow plug 49, and carries it together with the packing sleeve 50 and all connected parts upward with it.

What I claim and desire to cover by Letters Patent is:

1. A deep well pump adapted for insertion in a well bore including a tubing string having a lower working barrel near its lower end and an upper working barrel intermediate the lower working barrel and the point of discharge for said tubing, a packing sleeve adjacent and above the upper working barrel and arranged to be supported in a fluid-tight seat formed in said tubing, there being ports in said tubing below said seat and above said upper working barrel, a fluidtight hollow plunger reciprocable in said lower working barrel, a fluid-tight hollow plunger rcciprocable in said upper working barrel, and a fluid-tight hollow plunger stem reciprocable in said packing sleeve attached to said upper plunger, said plungers being operatively connected in a sucker rod string, a check valve at the lower end of the lower working barrel permitting entrance of fluid from said well bore into said barrel, a traveling valve on the upper end of the lower plunger permitting egress of fluid therefrom into said tubing, a check valve at the lower end of the upper plunger permitting fluid to enter said plunger from said tubing, a second traveling valve on the plunger stem permitting discharge of fluid therefrom into said tubing, said upper and'lower plungers being of approximately the same diameters, said plunger stern being of substantially smaller diameter.

2. In a device of the character described, a tubing string having a working barrel near its lower end, and an upper working barrel closed at its upper end to pressure outside thereof and within the tubing, intermediate the lower working barrel and the point of discharge for said tubing, a sucker rod string in said tubing, hollow plungers reciprocable with saidsucker rod string in each of said working barrels, a hollow stem in said sucker rod string adapted to reciprocate through the upper end of said upper barrel and communicate fluid from below the upper plungor to above the upper barrel, means to relieve pressure in said upper barrel above the plunger,

and valvular means adapted for upward displacement in, respectively, the lower end of said lower barrel, the lower plunger, and said hollow stem.

3. In a device of the character described, a tub a sucker rod string within said tubing, a pump comprising a barrel and a hollow piston at the lower end of said tubing string, adapted to pump iiuid upwardly in said tubing on the ing string,

downward stroke of said piston, a pipe in said sucker rod string above said barrel, a piston mounted on said pipe adapted to close the bore through said tubing around the pipe, m ans connected with the tubing above said piston and around said pipe to close the bore therethrough to pressure thereabove, means to relieve pressure between said upper piston and said last--mentioned means, and valvular means adapted for,

upward displacement in, respectively, the lower end or" said barrel, the lower piston, and said' pipe.

4.1m a device of the character described, a tubing string, a sucker rod string within said tubing, a pump comprising a barrel and a hollow piston at the lower end of said tubing string, adapted to pump fluid upwardly in said tubing on the downward stroke of said piston, a pipe in said sucker rod string abovesaid barrel, a piston mounted on said pipe adapted to close the bore through said tubing to pressure from above, a packer arranged to be supported in a fluid tight seat formed in said tubing and carrying a packing sleeve to effect a seal within the tubing above and below said packer, means to relieve pressure between said upper piston and said packer, and valvular means adapted for upward displacement in, respectively, the lower barrel, the lower piston, and said pipe.

5. In a device of the character described, a tubing string, a stem within said tubing, a working barrel suspended by said tubing, a hollow member connected to said stem, closure means carried by said tubing above said barrel to close the bore of said tubing around said member, a plunger slidably fitting said working barrel and suspended by said stem, communicating means between the zone between said plunger and 010-- sure means and the areaoutside of said tubing and barrel, means to communicate the area below the plunger with the zone above said closure means, valve means normally closing said lastnamed means but openable to pressure therebelow, a second working barrel below the abovementioned plunger suspended by said tubing string, a plunger suspended by said stem slidably disposed in said second barrel, and valvular means in said plunger adapted for upward displacement.

6. In a device of the character described, a sectional tubing string, collars connecting the sections of said tubing string together, an upper lower working barrel in said tubing string spaced from each. other and clamped between pairs of said means to close the upper working barrel to pressure thereabove, a sucker rod string within said tubing, hollow plungers reciprocable with said sucker rod string in each of said working barrels, a hollow stemin said sucker rod string the upper of said upperbarrel and communicate fluid from below the upper plunger to above the upper barrel, valve means recipr cable with said rod string to close the area between said plungers to fluid above said firstnamed meansl, means to relieve pressure in said upper barrel above the plunger, and valvular means adapted for upward displacement in, respectively, the lower end of said lower barrel and the lower plunger. v

7. In a device of the character described, a sectional tubing string, collars connecting the sections of said tubing string together, an upper and a lower working barrel in said tubing string spaced from each other and clamped between pairs of said collars, means to close the upper working barrel to pressure thereabove, a sucker rod string within said tubing, hollow plungers reciprocable with said'sucker rod string in each of said working barrels, a hollow stem in said sucker rod string adapted to reciprocate through the upper end of said upper barrel and communicate fluid from below the upper ment in, respectively, the lower end of said lower barrel, the lower plunger, and said hollow stem.

8. In a device of the character described, a tubing string, a stern within said tubing, a working barrel suspended by said tubing, a hollow member connected to said stem, closure means carried by said tubing above said barrel to close the bore of said tubing around said member, a lunger slidably fitting said working barrel and suspended by said stem, communicating means between the zone between said plunger and closure means and the area outside of said tubing and barrel, means to communicate the area below the plunger with the zone above said closure means, a second working barrel below the abovementioned plunger suspended by said tubing string, a plunger suspended by said stem slidably disposed in said second barrel, valvular means in said hollow member and said last-named plunger adapted for upward displacement, valve means in said lower barrel, and means to reciprocably connect said valve means and said last-mentioned plunger to efiect removal of said last-named valve means with removal of said stem from said tubing string;

BERNARD H. SCOTT.

plunger to above the upper barrel, means to relieve pres-

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