US3020848A - Oil well pump - Google Patents

Description

W. G. GREEN OIL WELL PUMP Feb. 13, 1962 3 Sheets-Sheet 1 Filed July 23, 1958 W. G. GREEN OIL WELL PUMP Feb. 13, 1962 5 Sheets-Sheet 2 F IG. 5

Filed July 25, 1958 FIG. 3

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w. 5. GREEN 3,020,848

011. WELL PUMP 3 Sheets-Sheet 3 Feb. 13, 1962 Filed July 23, 1958 kw I BY J A. 441.49.

flas/vr 3,020,848 OIL WELL PUMP William G. Green, Tulsa, Okla. (3210 46th Ave. N., St. Petersburg, Fla.) Filed July 23, 1958, Ser. No. 750,390 1 Claim. (Cl. 103-46) This equipment relates to oil Well production equipment and more particularly to a fluid pump of the free piston type.

An object of this invention is to provide an oil pump assembly which may be lowered into the. oil pool of a gas pressure well and which pump will lift the oil to the surface of the well with a minimum loss of gas pressure.

Another object is to provide a gas operated, oil weight controlled lift pump which operates automatically and under the well pressure conditions.

And a further object is to provide a lift pump assembly which ejects oil up a long pipe height with a controlled amount of lost gas for each oil ejection.

And yet another object is to provide an oil pump which is adapted to lift oil out of a well of great depth and which operates in stages, the initial stage being operated by the total bottom hole pressure, another stage being operated by the differential oil pressure, and another stage being operated by the gas pressure alone.

And another object is to provide an oil pump for lifting a column of oil out of a well by applying only the necessary amount of gas volume to do the job, and then relying on the immediate loss of pressure in the well to prevent the escape of gas after the necessary amount has been expended.

These and other objects and advantages will be apparent from an examination of the following specification and drawings in which:

FIG. '1 is an outline schematic drawing of an oil well installation employing the pump assembly of this invention.

FIG. 2A is cross sectional view of the pump assembly installed in a well bore in its initial operating position; FIGS. 2B-2E are additional views similar to FIG. 2A but shown schematically and diagrammatically in outline form to illustrate subsequent operating positions of this device.

FIG. 3 is a cross sectional drawing of the top portion of the oil well tubing shown in FIG. 1, and shown here in a horizontal position, and showing the top section of the oil pump assembly.

FIG. 4 is the next lower portion of the well tubing and the next subsequent section of the pump assembly.

FIG. 5 is a drawing of the next continuous subsequent portion of the pump and tubing to that shown in FIG. 4.

FIG. 6 is the next continuous subsequent drawing of FIG. 5.

FIG. 7 is a lower continuation of FIG. 6 showing the end of the pump assembly.

FIG. 8 is an end view looking up from the bottom of the well bore or as would be taken along the lines 88 of FIG. 7.

Referring now more particularly to the characters of reference on the drawing, it will be observed that the pump assembly, identified generally at 2 in FIG. 1 is installed at the lower end of a string of production tubing 3 in a well bore casing 4 which is sealed at its upper end at 5 relative to the tubing 3 at approximately the ground level L. The pump assembly 2 is immersed partly in the liquid oil 0 in the well bore and extends above the oil and into the gas zone G. At the top of the well bore a pressure gage 7 has been installed to check the gas pressure in the annulus between the casing 4 and tubing 3 for test purposes. The extreme upper end of the tubing 3 States Patent 0 extends up through the top of the sealed end 5 and is capped at 8 to seal off the tubing and also retain a bumper spring 10, against which a conventional free piston 15 of this assembly is adapted to abut. At a distance below the bottom of the piston 15 when the latter engages the spring 10, a T 16 is installed in the tubing to connect with flow line 17 through which the oil is delivered to storage tanks (not shown).

The lower end of the casing 4 may be open and extend into an oil pool P and it is perforated as shown at 19 where the perforations connect with a gas zone Z in the formation F to form a communication with the annulus for a restricted entry therein of the gas G.

The construction of the unique pump assembly 2 of this invention may be observed in FIGS. 3-8 to comprise basically a body 20 having a center tube 21 which extends axially through the assembly 2 for virtually its full length and a concentric housing 22 which surrounds the tube 21 and is spaced therefrom by collar 23 and trun nion assembly 24. A series of fixed disks 2629 divide the interior of the tube into separate compartments and a stationary end member 31 having a divider 32 provides another compartment by cooperation with the floating end member 34. A fitting 35 is threaded into divider 32 and is adapted to receive a valve stem 36 in sliding re lation to the fitting bushing 37 in such a manner that as long as the ports 38 of the channel 39 of valve stem 36 are in contact with the bushing 37, there will be no flow through the valve stem 36 by any oil 0 below the cap member 34. The main valve body 41 extends through the disks 27 and 28 in sliding but fluid tight relation, and both the valve body 41 and the piston 43 operate through the disk 29. The lower cap member 34 includes a ridge 45 which provides a captive fit with the end member 31 and an extension 47 thereon. An 0 ring 48 provides sliding but fluid tight seal between the members 32 and 34 and a compression spring 50 with a pre-set resistance is inserted between these members. The piston 43 is also held in its lowermost position by a pre-set spring 51. A channel 52 extends completely through the piston 43 and the upper end of this piston operates against a small spring 53 in the upper end of bore 54, and this bore opens laterally to port 55. The upper end of body 41 acts against a compression spring 57 which also seats against the fixed disk 27.

A relatively long tubing 60 extends from a point above the oil level in the casing so as to admit gas pressure into the compartments defined by the tube 21 at the ports 61 and 62. A second tubing 64 extends down along and adjacent the opposite side of the center tube 21 to provide an oil passageway from the oil below and in the compartment adjacent fitting port 65 to the compartment adjacent port 66 and thence toport 67 which is adjacent the output chamber 68 of the pump assembly 2 which is directly above the normal position of rest for free piston 15.

The main valve body 41 includes an axial gas channel 70 which extends from a top opening downward to a side port 71 just above the oil port 65. Ports 71 and 55 open into separate grooves 72 and 73 respectively to facilitate discharge. The oil delivery tubing 64 includes a ball check valve 75 between its ports 65 and 66 to prevent unintended return of the oil to its inelt chamber The operation of the complete pump assembly 2 may be observed by reference to the five stages shown at AE of FIG. 2. The first stage, FIG. 2-A shows the pump assembly 2 in its initial condition upon being lowered into an oil pool P in a well bore. In this position, the free piston 15 is at rest on disk 26, and the valve body 41, piston 43, and floating end member 34 are all in their lowermost position. FIG. 2-B represents the second stage of the pump operation where the cup 34 has started to move the piston 43 and valve 41 upward. FIG. 2-C represents the third stage wherein the valve 41 has moved upward sufiicient to permit oil to flow through passageways in the pump assembly into the discharge chamber 68. FIG. 2-D shows the fourth stage in this operation when the gas valve port 61 is opened through passageways in the pump assembly to its pressure or propulsion chamber 88. The fifth stage is depicted in FIG. 2E to represent the pump just at the point the oil is beginning to be discharged at the surface of the well. After this event the various valves and operating parts of the pump return to their initial position as shown in FIG. 2-A and the free piston continues upward until it is rebounded by the spring 10 (FIG. 1) and thereafter returns to its position of rest against disk 26.

When the surrounding oil has come in contact with the lower end 811 of member 34 and its pressure exceeds the pressure of spring 50, the member 34 will move upward and valve stem 36 will pass through the bushing 37 until it opens into chamber 76 and the oil then flows freely through channel 37 until it has built up sufficient pressure against the bottom of piston 43 to raise it upward until its enlarged section 81 abuts the lower end 82 of valve body 41 and then proceeds to raise the valve body 41 upward until a detent 83 in the upper valve stem 84 engages the spring-loaded ball 85 to assume momentarily the third stage of operation as seen in FIG. 2-C. At this stage the oil port "55 is aligned with fitting port 65 and the oil coming in through the lower valve 36 is able to pass through the pump and into tubing 64 past ball valve 75 and up through port 65 whereat it fills the outlet chamber 68 above piston until the oil now in tubing 64 above port 66 exceeds the resistance of spring 57, at which point the piston 86 is raised, and

being integral therewith causes the entire valve body 41 to raise until the second detent 87 engages the ball assembly 85. At this point the gas tubing port 61 will coincide with the gas inlet port 71 and pressurized gas will pass up through the channel 70 until the pressure in chamber 88 is greater than the combined weight of the oil in outlet chamber 68 and the weight of the piston 15 and friction resistance, whereupon the free piston 15 rises up the tubing 3 until the oil begins to spill out into flow line 17, whereafter the resistance of the free piston 15 on the lifting gas becomes less and the gas is permitted to expand and more rapidly push the piston 15 up and the oil out. The restricted opening of port 71 prevents the gas from the annulus A from equalizing under the free piston as fast as the gas is expanding in the tubing at that location. When the oil has all gone out into the flow line 17, the free piston impacts against the bumper spring 10 and the operating gas also escapes out through the T 16. When this expansion and reduction in gas pressure begins to take place, the pressure exerted on the oil in the tubing 64 and under piston head 86 drops off until it is no longer able to balance the pressure of spring 57 so that the latter overcomes the resistance of the detent 87 and ball 85 and returns piston 86 and valve body 41 to its initial position of rest against disk 29. Further down the valve body 41, the 0 rings 88 move to seal off the gas inlet port 61 so that no further gas is lost after the oil quantity is delivered. The fact that the use of a quantity of gas from annulus A has reduced the pressure there, the lower springs 51 and 50 are now able to return the piston 43 and end member 34 to their initial position, and ready for the next pumping action which will occur when the formation pressure has built up the pressure in the annulus to an operational value again.

The presence of by-pass channel 89 to provide communication between the enclosed chambers 90 and 91 will prevent high resistance due to compressing or expanding air entrapped in these chambers. Other similar channels may be provided where desirable in this assembly.

From the foregoing description it will be readily seen that there has been produced a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of this invention, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention as defined in the appended claim.

Having thus described the invention, what is claimed as new and useful and is desired to be secured by Letters Patent is:

A pump assembly for an oil well having a pressurized gas zone, an oil zone below the gas zone and subjected to the pressure therefrom at the oil level in the well bore, comprising: a tube containing atmospheric pressure extending from the surface of the well bore down to the pump body, a free piston in the tube, an oil port in the tube above the free piston, an oil passageway connecting the oil port to the pressurized oil, a gas port in the tube below the piston, a gas passageway connecting the pressurized gas zone through the gas port with the underside of the piston, a central valve in said pump body initially operated by the combined oil and gas pressure to introduce oil through the oil passageway and into the tube, a channel from the central valve to the oil zone at the lower end of the pump body, a lower valve operated by the combined oil and gas pressure to close the channel when this combined pressure is below a certain valve, means in said central valve operated by the weight of the oil in said first named passageway to shut off the oil passing through said oil port and introduce pressurized gas through said gas port and lift said free piston and oil there above to the surface of the well, and means in said central valve to shut off the gas port when the pressure in said tube drops sharply,

and means to shut off said lower valve when the pressure in said gas zone drops off.

References Cited in the file of this patent UNITED STATES PATENTS 1,943,522 Fletcher Jan. 16, 1934 2,013,111 Scott Sept. 3, 1935 2,246,577 Davis June 24, 1941 2,508,174 Knox et al. May 16, 1950

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