US2319749A - Bore hole pump - Google Patents

Description

May 18, 1943.

BORE HOLE PUMP Filed July 22, 1941 l. s. SALNIKOV 3 Sheets-Sh 1 g 4 F/G. L

9 [M INVEIIVTOR,

ATTORNEY May 18, 1943. s. SALNIKOV BORE HOLE PUMP Filed July 22/1941 .3 Sheets-Sheet 2 INVENTOR. BY

ATTORNEY May 18, 1943., s. SALNIKOV 2,319,749

BORE HOLE PUMP Filed July 22. 1941 3 Sheets-Sheet 3 Patented May 18, 1943 BORE HOLE PUMP Ivan S. Salnlkov, Tulsa, Okla., assignor to Stand an! Oil Development Company, a corporation of Delaware Application July 22, 1941, Serial No. 403,501

Claims.

The present invention relates to bore hole pumps.

In the past, oil or other fluid occurring in a sub-stratum has been brought to the surface either by being allowed to flow to the surface under its own pressure or, where sufficient formation pressure did not exist, by pumping or gas lifting. Bore hole pumps, particularly for deep wells, in general, suffer from the disadvantage that the eiliciency of the pump decreases with depth. The principal reason for this loss of efficiency is that as depth increases, in order .to stay within the limits of tensile strength of the sucker rods it is necessary to reduce the diameter of the piston which in turn reduces the capacity of the pump,

According to the present invention advantage is taken of the fact that in deep wells, long strings of tubing must be employed and under the influence of pressure this tubing can be made to elongate to the extent that its lower end may travel a distance of many feet depending'upon the overall length of the tubing. Therefore, by the present invention, the sucker rod is eliminated and is replaced by the tubing itself which, however, is not reciprocated in the manner of conventional sucker rods, but is subjected to fluctuations in pressure which cause its lower end to reciprocate in the manner of a piston.

In the system of the present invention the lower end of the tubing is formed with an enlarged head which acts as a piston and which moves in a cylinder provided for the purpose, said cylinder being mounted independently of the tubing. Hydraulic pressure is then applied to the upper face of the enlarged head of the tubing causing the tubing to elongate and the enlarged head to move downwardly in the piston. This builds up pressure under the lower end of said enlarged head and this pressure is utilized to pump oil to the surface. When the pressure on the upper side of said enlarged head is released, the tubing contracts causing the enlarged head to move upwardly thereby creating suction beneath the lower face of the enlarged head and sucking oil out of the formation.

The principal object of the present invention, therefore, is the provision of a pumping system and apparatus in which advantage is taken of the considerable amount of elongation which long strings of tubing will undergo with increases in pressure. An additional object of the present invention is the provision of a pump of the character described in which the tubing itself is caused to act, in effect, as a piston by having its lower end reciprocated in response to intermittent increases and drops in pressure applied at the surface.

An additional object of the present invention is provision of a bore hole pump which will be simple in construction and possessed of a minimum number of moving parts and which will be entirely free from frictional elements which require lubrication. Among the advantages of the pump in the present invention are that its operation is subject to full control from the surface and that due to its construction there is very little chance for it to get out of order whereby the frequency with which it must be withdrawn from the bore hole is dictated solely by the durability of the metals which make up the moving parts.

Further objects and advantages of the present invention will appear from the following detailed description of the accompanying drawings, in which Fig. 1 is a front elevation partly in section of one embodiment of the pumping system of the present invention;

Fig. 2 is a similar view of a modified form of the embodiment shown in Fig. 1; and,

Fig. 3 is a similar view of still another embodiment of the present invention.

Referring to the drawings in detail and particularly to Fig. 1, numeral I designates a bore hole drilled from the surface to a producing hori-- zon 2. The bore hole is lined with casing 3 which is sealed off at the surface by casing head 4 which may be provided with a gas draw-off line 5. Mounted on the casing head is a tubing head 6 which carries a tubing 1 suspended in the bore hole and of suflicient depth so that its lower end will be in the vicinity of the producing formation. Connected to the tubing head 6 is a drawoff line 8 which is adapted tov carry away any fluid which is brought up through the tubing 1.

Threaded to the lower end of the tubing 1 is a cylinder 9 which has a length, which will vary with the depth of the well and operating conditions to be employed, which will determine the amount of travel of a piston in this cylinder. In other words, the cylinder is made long enough to provide a full travel for the piston, to be hereinafter described. The lower end of the cylinder rests on a packing disc II) which is carried by acylindrical block I! which in turn is threaded into a collar H. The upper end of the collar I! has screw thread engagement with an outer cylinder I3 which is of larger diameter than cylinder 9 and concentric therewith so that an annular space I4 is formed between them. The upper end of cylinder I3 is threaded into a skirt H which is welded to the upper end of cylinder 9. The block H is placed against the lower end of cylinder 9 by screwing the collar i2 onto the lower end of cylinder i3. Screwed intothe lower end of collar I2 is a barrel i6 having an opening il! in its bottom over which is mounted a cage carrying a check valve i8.

Block H has a longitudinal passage l9 connecting the interior of cylinder 9 with the interior of barrel l5. Block II also has a trans verse passage 20 which terminates at its either end at the upper face of the block in fluid communication with the cylinder i3. This transverse passage is connected to the interior of the barrel l8 by a longitudinal passage 2| in which is mounted a check valve 22.

Mounted on top of tubing head 6 is another tubing head 23 from which is suspended a tubing 24 which-is substantially co-extensive with tub-' ing 1. At its lower end tubing 24 is formed into a plunger 25 which has afluid-tight fit with the inner surface of cylinder 9 and is provided with suitable packing rings 26. Just above the plunger 25 the tubing is provided with an opening 21. In the upper end of cylinder 9 is rigidly fixed a. sleeve 28 which has a diameter considerably smaller than that of cylinder 9 and which forms a cylinder for a piston 29 formed on tubing 24. Like the plunger 25 piston 29 is provided with suitable packing 30. The upper end of tubing 24 is connected to a line 3| which discharges into a tank 32. A branch line 33 is connected to line 3| and at their junction is a special valve 34 which can be manipulated to connect line 3| to tank 32 or to the branch line 33 as desired and which is preferably an automatic valve for making connections alternately at some selected frequency. Branch line 33 is the discharge line of pump 35. The intake line 36 is connected to the lower end of tank 32. A by-pass 31 is provided between lines 33 and 36 so that when valve 34 is closed against discharge line 33 the pump can continue to operate. In other words, the pump operates continuously and is only intermittently connected to line 3|.

As previously indicated the dimensions of the various parts of the pump are selected to suit a particular operating depth. For example, when producing from a formation of about 7500 feet, the cylinder 9 may be from 4 to 10 feet between the lower end of sleeve 28 and block depending upon the pressure which is to be applied by the pump. Of course, the length of the sleeve 28 will be about the same. because the piston 29 must have the same length of travel as the plunger 25. It will be understood, of course, that the dimensions of these parts will vary with different pumping depths and metals, as the tensile strength and resilience of these materials vary with depth and with the amount of pressure to be applied.

In operation, with the pump 35 disconnected from line 3|, the plunger 25 will occupy a position adjacent to the lower end of sleeve 28. At this point the check valves l8 and 22 will be seated and cylinder 9 and barrel l6 will be full of oil, as will also the annular space l4 and tubing 1 up to a certain level. It will be noted at this point that there are fluid connections 38 between annular space l4 and tubing 1 above piston 29. The pump is then connected to line 3| and high pressure fluid is forced into tubing 24, and discharges through opening 21 against the upper side of the plunger 25. As the pressure builds up the tubing 24 will elongate causing the plunger 25 to travel downwardly. It will be noted that this downward thrust of pressure would normally tend to cause tubing I to elongate, but this elongation of tubing 1 is opposed by the upward thrust of pressure against the lower annular face of the sleeve 28 which in effect forms a piston acting in opposition to the tendency of tubing i to elongate.

As plunger 25 moves downwardly it builds up pressure in the barrel i6 forcing ball I8 on its seat and ball 22 off its seat whereby the oil in the cylinderv 9 and barrel I6 is caused to flow through lenticular passage 20 into annular space l4 and thus into tubing 1 and draw-oil line 8.

When the plunger 25 reaches the bottom of its stroke the valve 34 is manipulated to disconnect line 3! from pump 35 and connect it to tank 32. This releases the pressure on the upper face of plunger 25 and permits the tubing 24 to contract drawing'the plunger upwardly in cylinder 9. At thi point the ball 22 is forced on its seat by the head of'liquid above it and as plunger 25 moves upwardly it creates a suction which decreases the pressure in barrel I6 to the point where the formation pressure can force the ball I8 off its seat permitting oil to flow in from the formation to flll barrel l6 and cylinder 9. After the plunger 25 has reached its upper extreme position the parts are then in position to start another cycle.

In order to compensate for the different weight on the different lengths of tubing in string, and thereby to more evenly distribute the elongation of the tubing,'it is advantageous to make the tubing 24 of different thickness at different depths, the thickness being greatest at the surface and diminishing with depth. By this expedient localized points of excessive fatigue may be avoided.

In Fig. 2, parts corresponding to parts shown in Fig. 1 carry the same numerals. The embodiment shown in Fig. 2 is identical with that shown in Fig. l with the exception that provision I is made to eliminate the possibility of gas lock occurring beneath the plunger in cylinder 3. For this purpose. tubing 24 carries an inner length of tubing of smaller diameter indicated by numeral 39. This inner length of tubing connects to the interior of tubing 1 through a T connection 40 located above the piston 29. The relative diameters of tubing 24 and 33 are such that an annular space is formed between them to provide for the passage of fluid through tubing 24 to outlet 21. The lower end of tubing 39 is threaded into the plunger 25 which for this purpose is provided with a central passage 4| in which is' seated a check valve 42. With this arrangement when the plunger 25 moves downwardly, fluid flows upwardly in not only through check valve 22 but through check valve 42 with the result that any gas which may have collected above the surface of liquid in the cylinder 3 will be carried out of the cylinder through tubing 39 and discharged into tubing 1.

In the embodiment shown in Fig. 3, it will be noted that a simplified form of surface equipment is illustrated. It will be understood that either this or the equipment shown in Figs. 1 and 2 may be employed in any case or any other equipment may be employed which will function to supply hydraulic pressure to the plunger in the bore hole intermittently. In the surface equipment in Fig. 3, line 3| is connected to a cylinder 43 which is provided with a piston 44 actuated by suitable engine 45. The piston has a longitudinal passage 46 provided with a safety valve 41 which may be set to maintain any desired maximum pressure in the working system. A reservoir 48 is shown connected to the cylinder 43 by pipe 49 which is so located that it,

forms a fluid connection between reservoir 48 and cylinder 43 on either side of the piston 44, depending on the position of the latter. Reservoir 43 is also connected to the rear end of the cylinder by a pipe 50. In the embodiment shown in Fig. 3 casing 3, tubing 1, and tubing 24 are the same as in Figs. 1 and 2. The difference between this embodiment and the others, in addition to the surface equipment, lies in the combination of elements connected to the lower end of the tubings I and 24.

The lower end of tubing I is connected by an adapter 3| to a cylinder of smaller diameter 52 which is equivalent to the cylinder formed by sleeve 28 in Figs. 1 and 2. The lower end of this cylinder is in turn connected by an adapter 53 to a larger diameter cylinder 54 corresponding to cylinder 3 in Figs. 1 and 2. The lower end of cylinder 54 carries a collar 55 which in turn carries a check valve assembly 56 having a central passage 51 and a ball valve 58.

Threaded on to the lower end of tubing-24 is a fitting 53 which carries at its lower end, a length of tubing 80. As shown, this tubing is provided with special rings 6| which are of an outside diameter such that they form a snug fluid tight flt with the interior surface of cylinder 52. The space between these rings will ordinarily carry oil which will act as a lubricant and seal. This ringed tubing is commonly known in the art as a grooved plunger. The tubing 60 extends down into the cylinder 54 and terminates in a head 62 which has a fluid tight fit with the interior surface of cylinder 54. The lower end of plunger 62 has a reduced diameter on which are arranged sealing cups 63 held in place by cap 64 which has a central opening 66 on which is seated a ball 66. The tube 60 is provided with perforations 81 just above the plunger 62.

The plunger 62 has a central opening in which is secured the lower end of an inner tubing 68,

the upper end of which terminates in the fitting full of power fluid. Likewise, the cylinder 43 on both sides of the piston is always full of this fluid.

At the beginning of a cycle the piston 44 is at the rear end of cylinder 43 and reservoir 48 is in open communication with the rest of the power fluid system. After the piston moves forward it seals off the reservoir from the rest of the system and builds up pressure in the rest of the system which results in a force exerted on the upperside of the plunger on head 62.- As this force increases the tubing 24 elongates and the plunger moves downward in cylinder 54. It may be noted here that the space between the large and small diameters of adapter 53 forms a working surface against which the pressure in cylinder 54 is thrust to offset the tendency of tubing 1 to elongate. In fact, the thrust against this working surface is suiliciently great to compensate for a portion of the weight oi the tubing I whereby this tubing actually contracts and thereby adds to the effective working stroke of the plunger.

As the plunger moves downwardly ball 58 is thrust on its seat and ball 86 is moved off its seat permitting the oil collected in the cylinder 54 to move upwardly through tubing 68 and into tubing 1 and thence to the surface. When the stroke of the plunger is completed the piston 44 is drawn back into cylinder 43, releasing pressure on top of the plunger and permitting tubing 24 to contract. At the same time tubing 1 elongates an amount equal to that which it contracted during the back stroke. It will be noted from the above discussion that the particular embodiments shown are illustrative only and are not presented as being definitive of the scope of the present invention. The basic feature of the present invention is the utilization of the amount of stretch available in the long string of tubing to operate a plunger for pumping purposes and the invention contemplates any combination of mechanical elements by which this principle may be utilized.

The nature and objects of the present invention having been thus described and illustrated what is claimed as new and useful and is desired to be secured by Letters Patent is:

l. An apparatus for producing oil from a subsurface formation which comprises a tubing for carrying said fluid extending from the surface substantially to said formation, an oil collection chamber carried by the end of said tubing, an entrance for oil from said formation into said chamber, a passage for oil from said chamber into said tubing, a piston adapted by reciprocation to force fluid from said chamber into said tubing, an elongated rigid fluid conducting hollow rod connecting said piston to the surface, and means at the surface for applying fluid pressure to the interior of said hollow rod to thereby extend said rod and actuate said piston.

2. An apparatusfor pumping fluid to the surface from a subsurface formation comprising a tubing for carrying said fluid extending from the surface substantially to said formation, a chamber carried by the lower end of said tubing, means for admitting fluid from said formation into said chamber, means for admitting fluid from said chamber into said tubing, a cylinder arranged in said chamber, a piston arranged in said cylinder adapted to exclude formation fluid from the portion of the cylinder above said piston, a fluid-conducting hollow rod connecting said piston to the surface, means for admitting fluid from said hollow rod to said cylinder behind said piston, and means for applying fluid pressure to said hollow rod.

3. An apparatus according to claim 2 in which there is provided in said cylinder an annular surface rigidly related to the tubing and adapted, by affording a working surface for the pressure fluid admitted into said cylinder behind said piston, to exert an upward thrust against said tubing when pressure fluid is applied to said piston to thereby prevent stretching of said tubing.

4. An apparatus according to claim 2 in which means are provided at the surface for alternately applying fluid pressure to said piston and releasing said pressure.

5. An apparatus for producing oil from a subsurface iormation which comprises a tubing for carrying said fluid extending from the surface substantially to the formation, an oil collection chamber carried by the end of said tubing, an entrance for oil from said formation to said chamber, a passage for oil from said chamber into said tubing, 2. piston adapted by reciprocation to force fluid from said chamber into said tubing, means adapted to be arranged at the surface for actuating hydraulic fluid for operm ating said piston, and a pipe for conducting said hydraulic fluid from the surface to said piston connected to said piston, said pipe being of such length and tensile strength that, upon application of suflicient pressure to said piston, it will stretch sufficiently to provide the downward travel of said piston, and upon the release of said pressure will contract and move the piston upwardly.

IVAN S. SALNIKOV.

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