US3040673A - Tubular sucker rods - Google Patents

Description

June 26, 1962 H. DUNBAR 3,040,673

TUBULAR SUCKER RODS Filed Jan. 25, 1960 2 Sheets-Sheet 1 Huey Dunbar Inventor June 26, 1962 H. DUNBAR TUBULAR SUCKER RODS 2 Sheets-Sheet 2 Filed Jan. 25, 1960 FIG. 3

Inventor Huey Dunbar By% Attorney United States Patent Jersey Production Research Company, a corporation of Delaware Filed Jan. 25, 1960, Ser. No. 4,305

7 Claims. (Cl. 103-179) This invention relates to well pumping equipment and more particularly to well pumping equipment for deep wells. It relates especially to a system of pumping a deep well by using hollow sucker rods.

In pumping oil wells it is a common practice to suspend a string of tubing from the surface of the earth to a point below the level of the oil in the well and to reciprocate a plunger within and near the bottom of the tubing by means of a long line of sucker rods extending through the tubing and motivated by a power unit at the surface of the earth. It is obvious that a well may attain such depth that the strain on the sucker rods Will reach a value in excess of the tensile strength of the rods, entailing parting or rupture of the rod. When the sucker rods break, a great expense and loss of time is incurred in replacing the broken rods.

Accordingly an important object of this invention is to reduce the strain on a string of sucker rods so as to minimize breakage thereof.

It is another object of this invention to provide a system whereby the effective weight of the long line of sucker rods on a pumping unit at the surface is reduced. 'An'additional object of the invention is to provide a system so that larger bore pumps can be set deeper to produce higher volumes of fluid than is possible with any conventional sucker rods.

These and other objects and details of the invention will be apparent from the following description, when read in connection with the accompanying drawings; wherein:

FIG. 1 illustrates, partly in section, a part of an oil well equipped with pumping means and tubular sucker rods embodying features of the invention;

FIG. 2 is a horizontal section on the line Z-Z of FIG. 1; and

FIG. 3 illustrates a different embodiment showing a diflerent pumping means.

Referring to the drawing, casing 10, lining the well, is illustrated as set in the top portion of producing reservoir 12. Casing has perforations 14 so that oil may flow from the reservoir 12 into the interior of casing 10.

Suspended within casing 10 is tubing 16. Tubing 16 extends from the surface of the earth to near the bottom of casing 10 or below the liquid level of the oil in casing 10 to be pumped to the surface.

A string of hollow sucker rods 18 is suspended within tubing 16. Conventional pumping equipment (not shown) at the surface of the earth is provided to reciprocate sucker rods 18 in the tubing.

Suspended at the lower end of tubing 16 is working barrel 20. Adapted to reciprocate within working barrel 20 is piston 22 which is provided with upper piston ring 24 and lower piston ring 26. Within piston 22 is passage 28 having check valve 30 which is of a character to prevent the downward flow of fluid through passage 28. The lower end of working barrel 20 is enclosed by plate 32. Bottom plate 32 of working barrel 20 has passage 34 with check valve 36 which is of a character to permit oil to flow from the casing into the working barrel but prevents oil flowing downwardly through passage 34.

In a preferred embodiment hollow sucker rod 18 has a connecting member 38 attachable to piston 22 by a lock nut 23. Member 38 is preferably solid and has a reduced cross section from that of hollow rod 1-8. A pack- 3,040,673 Patented June 26, 1962 ing means is provided in the lower end of tubing 16 to seal the space between connecting member 38 and the inner walls of tubing 16. Although there are many ways of providing this sealing means it can conveniently be done as illustrated. A packing recess 42 is provided in upper end plate 40 of 'working barrel 20. Packing 44 is placed in packing recess 42 and is held there by bushing 46. It is thus seen that an elongated annular reservoir 47 is formed in tubing 16 above the sealing means and the exterior of hollow sucker rod 18.

Passageway 50 with check valve 49 is provided in plate 40. Passageway 50 established fluid communication between the interior of working barrel 20 above piston 22 and the annulus between tubing 16 and casing 10.

Although not necessary, check valve 49 may be installed in passageway 50 to permit fluid to flow out of working barrel 20 through passageway 50 but prevent it entering therethrough.

An annulus packer 52 seals the annulus between working barrel 20 and casing 10 at a position below the outlet of passageway 50. Many well known conventional packers are available which are suitable for this use.

A liquid 54 is retained in reservoir 48 to at least partially sustain the weight of hollow sucker rod 18. The liquid should have as high a specific gravity as possible to add buoyancy to hollow sucker rod 18. The specific gravity of the liquid should preferably exceed 1.00. Liquid 54 should further be noncorrosive to the tubing or hollow sucker rods. The liquid also should not contain settleable solids. A suitable liquid is a solution of potassium carbonate in water. In a specific example, potassium carbonate was added to distilled water in the proportion of about 616 grams of potassium carbonate per 500 milliliters of Water. The gravity of this solution at F. was 1.53.

In the operation of this apparatus, tubing 16 (with hollow sucker rod 18 suspended therein and pumping means suspended at the lower end of the tubing in a manner similar to that illustrated in FIG. 1) is lowered within a well to the fluid to be produced. Annulus packer 52 is then set below the outlet of passageway 50. Liquid 54 is then used to at least partially fill reservoir 48. Pumping operations are then begun by reciprocating sucker rod 18 by a conventional pumping unit at the surface of the earth. Oil then flows from reservoir 12 through perforations 14 and into casing 10 below annulus packer 52. The oil then flows into working barrel 20 through passage 34 and check valve 35. On the down stroke of piston 22 oil flows upwardly through passage 28 through check valve 30 and into the space above piston 22 in working barrel 20. On the upstroke of piston 22, oil above piston 22 is forced through passageway 50 and check valve 49 and thence up the annulus between tubing 16 and casing 10 to the surface of the earth.

It is thus clear that at least partial flotation of the hollow sucker rod is effected, and that the use of a high specific gravity fluid increases v the effect of flotation. Therefore, the use of a hollow sucker rod system of this invention permits the setting of and use of larger pumps at greater depths than is possible with conventional sucker rods.

The use of this invention materially reduces the weight on the sucker rods and gravity of about 1.30 in tubing 16. It can be readily calculated that buoyancy will support 91% of the weight of the rod thus leaving only 9% to be supported at the top. The stretch of the sucker rod due to its own weight is likewise reduced. The design of a hollow rod for a particular job will depend upon many factors such as the depth from which fluid is to be pumped, the rate'of pump ing, the nature of the fluid to be produced and the density of the liquid. I

FIG. 3 illustrates another embodiment of the invention using a full-opening retrievable pump unit. Parts in FIG. 3 which are identical to parts in FIG. 1 will be given the same reference numerals. The illustrated full-opening retrievable pump unit includes the pump barrel 56 mounted in the lower end of tubing 57. This is held in place by a bottom lock holddown means including an expanding nose 58 and a receiving recess 60' in the lower interior of tubing 57. For a description of an API bottom lock holddown, reference is made to Continental-Emsco Company illustrations on page 1421, volume I of the 23d (1958-1959) revision of the composite catalog published by World Oil, PO. Box 2608, Houston, Texas. A pump piston 62 is attached to connecting member 3-8 by locknuts 64. The upper end of pump barrel 56 is closed by plug 66 which has an aperture 68 therethrough for the passage of connecting rod 38. Sealing means 70 effects a sliding and sealing relationship between connecting mem ber 38 and cap 66. The lower end of pump barrel 56 is enclosed by a lower cap 72 having a passage 74 therethrough. A check valve 76 is located in passageway 74 and permits the flow of fluid only in an upwardly direction therethrough.

As shown piston 62 has a passage 78 vertically therethrough. Passage 78 has check valve 80 which permits the flow of fluid upwardly through passageway 78 but prevents its flowing downwardly therethrough. Packer 52 seals the annulus between tubing'57 and casing 10. Ports 82 and 84 in thewalls of pump barrel 56 and tubing 57 respectively provide fluid communication between the upper interior of pump barrel 56 and the annulus between casing and tubing 57. An internal recess 88 in tubing 57 serves to interconnect ports 82 and 84 so that exact alignment of the ports is not essential. Sealing means 90 above ports 84 and 82 provide a sealing relationship between the upper end of pump barrel 56 and tubing 57. Another sealing-means 9-2 provides a-fluid-type seal between the lower end of pump barrel 56 and tubing 57.

In the embodiment shown in FIG. 3 if it is desired to remove pump barrel 56 for any reason such as repair of check valve, seals, etc., it is seen that the pump barrel 56 may be removed therefrom without removing or pulling tubing string 57. An upward pull on tubing 18 while tubing 57 is held stationary results in piston 62 being pulled upwardly against plug 66. Further upward movement of pump rods 18 causes expanding nose 58 to be compressed and move out of recess 60. The pumping unit then may be pulled to the surface for repairs.

It will be noted that the foregoing description is concerned with two structural embodiments of the invention. It is possible to produce still other embodiments without departing from the inventive concept herein disclosed, and it is desired therefore that only such limitation be imposed on the impending claims as are stated therein.

What is claimed is:

1. A well pumping apparatus comprising a combination of a string of tubing, means forming an elongated reservoir in said tubing, a string of hollow sucker rods reciprocably and sealingly extending longitudinally through said reservoir, a high density liquid in said reservoir to put buoyancy upon said rods, pumping means reciprocable by said hollow sucker rods to pump fluid upwardly from the bottom of the well exterior of said tubing to the surface of the earth.

2. A pumping apparatus for removing oil from a well comprising a casing in said well, a tubing string suspended within said casing, a hollow rod suspended'reciprocally in said tubing, packing means disposed in the lower part of said tubing sealingly engaging the inner wall of said tubing and slidably andsealingly engaging said rod, an annulus packer sealingly engaging said tubing and said casing, pumping means suspended at the lower end of said tubing string below said packer and connected'to the lower end of said rod, and of a character to pump oil from below said annulus packer to above said annulus packer, and a liquid within said tubing above said packing means.

3 An apparatus as defined in claim 2 in which the liquid is a solution of potassium carbonate in water.

4. An apparatus for pumping liquid from a Well comprising a casing, a tubular member suspended within said casing, a hollow sucker rod reciprocable within said tubular member, means forming a liquid reservoir within said tubular member and exterior of said rod, an annulus packer between the lower end portion of said tubular member and said casing, pumping means reciprocable by said rod which sealing'ly extends through the bottom of said means for forming a liquid reservoir, said pumping means being further characterized in having its suction side below said annulus packer and its discharge side in the annulus between said casing and said tubular member above said annulus packer, and a liquid within said reservorr.

5. An apparatus as defined in claim 4 in which the specific gravity of the liquid is greater than 1.00.

6. An apparatus of the character described for pumping fluid from a well bore comprising an elongated reservoir suspended within said well bore, a liquid in said reservoir, a hollow rod reciprocably mounted within the liquid in said reservoir, an extension rod connected to the lower end of the hollow rod and extending in a sealing and sliding relationship through the bottom of said reservoir, said extension rod sealing the lower end of the hollow rod, pumping means supported at and from the lower end of said reservoir including a piston mounted in said pumping means connected to and motivated by the reciprocation of said rods and conduit means from the discharge side of said pumping means extending to the surface of the earth.

7. An apparatus as defined in claim 6 in which the liquid is a solution of potassium carbonate and water.

References Cited in the file of this patent UNITED STATES PATENTS 1,900,588 Scott Mar.'7, 1933 1,906,933 Standlee- May 2, 1933 2,051,089 Lamb Aug. 18, 1936 2,797,642 Bloudoff' July 2, 1957

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