US3672795A

US3672795A - Cable-suspended,linear-supported electric pump installation in well casing

Info

Publication number: US3672795A
Application number: US112610A
Authority: US
Inventors: Armais Arutunoff; John C O'rourke
Original assignee: TRW Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1971-02-04
Filing date: 1971-02-04
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27

Abstract

A CABLE-SUSPENDED, SUBMERGIBLE ELECTRIC PUMP INSTALLATION FOR USE IN A WELL CASING, INCLUDING CONCENTRICALLY CONNECTED PUMP, MOTOR AND MOTOR PROTECTING UNITS. A RETRIEVABLE CYLINDRICAL LINER ENCIRCLES THE CABLE AND EXTENDS INTO THE WELL CASING FROM GROUND LEVEL TO ENCLOSE THE DISCHARGE HEAD OF THE PUMP UNIT, WHERE A SHOE IS PROVIDED ON THE LINER TO ACTUALLY SUPPORT THE INSTALLATION AT A PREDETERMINED OPERATIVE ELEVATION IN THE WELL. THE PUMP INTAKE COMMUNICATES WITH THE WELL FLUID IN THE CASING, AND THE PUMP DISCHARGES TO THE EARTH''S SURFACE THROUGH THE LINER. THE ANNULUS BETWEEN THE LINER AND CASING ACTS

AS A GAS SEPERATOR. ALL ELECTRIC CONNECTIONS AND SPLICES ARE MADE IN A LOW PRESSURE ZONE EFFECTED BY THE PUMP INTAKE, REMOVED FROM THE HIGH PRESSURE ZONE INFLUENCED BY THE PUMP DISCHARGE, TO AVOID THE DETRIMENTAL EFFECTS OF HIGH PRESSURE ON THE CONNECTION AND SPLICES. THE INSTALLATION ALSO INCLUDES MEANS TO PERMIT THE FLUSHING OF SAND WHICH MAY ACCUMULATE IN THE LINER ADJACENT THE PUMP DISCHARGE HEAD.

Description

June 27, 1972 A. ARUTUNOFF ETAL 3,672,795

CABLE-SUSPENDED, LINER-SUPPORTED ELECTRIC PUMP INSTALLATION IN WELL CASING 3 Sheets-Sheet 1 Filed Feb. 4, 1971 llvvmrans ARMA/S AFUTU/VOFF JOHN C OROURKE ATTORNEY June 27, 1972 A. ARUTUNOFF ET AL 3,672,795

CABLE-SUSPENDED, LINER-SUPPORTED ELECTRIC PUMP 197 INSTALLATION IN WELL CASING 4, l

5 Sheets-Sheet 2 Filed Feb.

7/ A w 7 8 A m 2 i n Q 4 E w a 2 W Wm 1 v\ w A I HI I n////\, X/ ////H U A. ARUTUNOFF ETAL 3, 7 CABLE-SUSPENDED, LINER-SUPPORTED ELECTRIC PUMP INSTALLATION IN WELL CASING 3 Sheets-Sheet 5 E Y L y a H 2 June 27, 1972 Filed Feb. 4, 1971 SAN LIFT LOW 24 PRESSURE lNVE/VTORS ARMA/S ARU TUNOFF JOHN a. OROURKE 5y ATTORNEY AND.

HiGH PRESS.

United States Patent 3,672,795 CABLE-SUSPENDED, LIN EAR-SUPPORTED ELEC- TRIC PUMP INSTALLATION IN WELL CASING Armais Arutunoif and John C. ORourke, Bartlesville, 0kla., assignors to TRW, Inc., Cleveland, Ohio Filed Feb. 4, 1971, Ser. No. 112,610 Int. Cl. F04!) 17/00, 35/04; F03b 13/02 US. Cl. 417424 6 Claims ABSTRACT OF THE DISCLOSURE A cable-suspended, submergible electric pump installation for use in a well casing, including concentrically connected pump, motor and motor protecting units. A retrievable cylindrical liner encircles the cable and extends into the well casing from ground level to enclose the discharge head of the pump unit, where a shoe is provided on the liner to actually support the installation at a predetermined operative elevation in the well. The pump intake communicates with the well fluid in the casing, and the pump discharges to the earths surface through the liner. The annulus between the liner and casing acts as a gas separator. All electrical connections and splices are made in a low pressure zone effected by the pump intake, removed from the high pressure zone influenced by the pump discharge, to avoid the detrimental effects of high pressure on the connection and splices. The installation also includes means to permit the flushing of sand which may accumulate in the liner adjacent the pump discharge head.

BACKGROUND OF THE INVENTION In previous wire-line, suspended electric pump installations, such as disclosed in Arutunofl Pat. No. 3,411,454, issued Nov. 19, 1968, the installation was suspended in an existing casing and locked in position by an expandible slip arrangement located below the discharge tube of the pump unit, the area of the casing immediately below the pump discharge being provided with a rubber packer. The cable connections and splices were made above the packer and thus were subjected to the high pressure zone in the casing adjacent and above the pump discharge. This high pressure had a deleterious effect upon the cable connections and splices in that moisture under constant pressure was inclined to seep into the splices.

Furthermore, if repairs were required or a quantity of sand collected adjacent the pump discharge, it was necessary to pull the entire assembly, including the loaded packer, all the way out of the casing as a swab.

SUMMARY OF THE INVENTION The present invention employs the same general type of coaxially arranged, superposed pump, motor and motor protecting units suspended by a cable or wire line, but instead of using slips for anchoring the assembly directly to the interior of the casing, a tubular liner spaced inwardly from the existing casing, encircles the cable and encloses the discharge head of a pump unit, means being provided in the liner for supporting the suspended installation at a predetermined operating level in the casing. Instead of employing the casing for conducting the column of pumped fluid to the surface, in the present invention the liner which supports the pump unit is employed for conducting the pumped fluid to the surface.

Furthermore, in the present invention, relatively simple means are provided for flushing an accumulation of sand from the liner, adjacent the pump discharge by simply permitting relative longitudinal movement of the pump installation with respect to the surrounding liner.

Anotherimportant feature of the present invention "ice resides in the relationship of the pump discharge head and a supporting shoe forming a part of the liner, where by a packing between the shoe and pump discharge head eliminates the necessity of a packing in the well casing, such as required in said prior patent, and also acts to seal off the high pressure zone from the low pressure zone where the electrical connections and splicing are effected.

Another feature of the present invention is that the liner is retrievable and the suspended pump and motor assembly is of a diameter which permits its bodily with drawal to the surface through the liner. Thus, the liner and the pump assembly may be jointly withdrawn from the casing, or the pump assembly can be separately withdrawn through the liner.

A further advantage of the use of a liner in the present invention is that the annulus between the liner and well casing acts as a gas separator.

With the above and other objects in view which will appear as the description proceeds, the invention consists in the novel features herein set forth, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims.

DRAWINGS Referring to the drawings in which numerals of like character designate similar parts throughout the several views:

FIG. 1 is a sectional view showing the pump installation and supporting liner in place in a well casing;

FIG. 2 is a similar view showing the upper portion of the casing, liner and cable at ground level and actually represents a vertical continuation of FIG. 1;

FIG. 3 is an enlarged sectional view showing the engagement of the pump dischargehead with the supporting shoe connected to the liner; and

FIG. 4 is a similar view showing the pump head in elevated position with respect to the supporting shoe when it becomes necessary to flush accumulated sand from the area of the liner surrounding the pump head.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2 of the drawings, 10 represents a conventional well casing which extends from the earths surface into a fluid producing formation. A pump installation comprising an electrically driven centrifugal pump unit 11, a motor protector unit 12, and a pump motor unit 13, coaxially arranged in superposed relation, is lowered into a retrievable liner 14 which extends partially into the well casing from the earths surface. The liner 14 is secured at its upper end by liner head 15 (FIG. 2) and is of sufiiciently reduced diameter with respect to the well casing 10 to provide an annular passageway 16 between the liner and casing for the discharge of separated gas through gas outlets 17 in a casing head 18, as hereinafter referred to.

The pump installation is suspended in the liner 14 by a weight supporting and electrical conducting cable 19, which is supported at the earths surface by any suitable means, such as the cable clamp diagrammatically shown at 20 in FIG. 2. The cable 19 extends downwardly through the liner head, and at its lower end, the weight supporting strands of the cable are attached to the pump installation at 22 by any suitable means, such, for example, as that shown in the Arutunoff Pat. No. 3,424,485.

In the present invention, the electrical conducting wires in the core of the cable extend downwardly from the cable anchor 22 into a connecting or splicing chamber 23, where they are suitably connected to conducting wires 24 extending downwardly alongside the pump installation to the motor unit 13, as seen in FIG. 1.

As best seen in FIG. 3, the lower end of the liner 14 threadedly engages a supporting shoe 25, the lower portion of which is thickened as at 21 to provide an annular inclined shoulder 26 which is adapted to support a complementary radially enlarged flange 27 formed at the upper extremity of the pump discharged head 28. The splicing chamber 23 is threadedly secured to the pump discharge head 28 above the flange 27, as at 23a (FIG. 3), and a suitable seal 23b is provided to seal oil the interior of the splicing chamber from the interior of the liner, as will later appear.

The inner diameter 26a of the enlarged portion 21 forming the shoulder 26 in the shoe 25 is of a size to receive the pump installation including the pump 11, protector 12 and motor 13 to permit the withdrawal of the units of the entire installation below the flange 27, through the liner. Also, the liner and the supported pump installation can be withdrawn simultaneously from the casing.

A passageway 29 extends diagonally through the pump discharge head 28 from the interior of the splicing chamber 23 to receive the spliced conductors 24, which, as before stated, extend downwardly to the motor alongside the pump unit and installation. The discharge head 28 is also provided with discharge passageways 30 which are directed to conduct the pumped fluid entering the pump through intake 11a to the interior of the liner 14, which, in turn, conducts the pumped fluid to the liner head 15 where it is discharged through passageways 15a (FIG. 2).

As previously pointed out, one of the primary features of the present invention resides in its provision of means for making all electrical connections and splicing in a low pressure zone,-as distinguished from prior Pat. No.

3,411,454, where splicing was accomplished in a high pressure zone adjacent the pump discharge. In the present invention, a low pressure zone surrounds the pump intake 11a and the collective pump installation, and, of course, extends upwardly through the casing 10. A high pressure zone exists upwardly beyond the pump discharge head 28, where fluid under high pressure is forced upwardly through the liner 14 and around the splicing chamber 23. As seen in FIG. 3, the interior of the splicing chamber 23 is in communication with the low pressure zone of the casingthrough passageways 29 which receive the conductors 24, rubber O-ring seals 31 being provided between the pump discharge head 28 and the annular thickened end 21 of the shoe 25 to prevent the high pressure in the liner 14 adjacent the discharge ports 30 of the head 28, from entering the interior of the splicing chamber 23 through passageways 29, and confines the high pressure within the liner 14. In addition to the seal 23b at the lower end of the liner, where it connects to the pump discharge head, the upper end of the splicing chamber may be sealed at 32 by any suitable means to insure the maintenance of low pressure in the splicing chamber. Thus, deleterious elfects of high pressure on the electrical connections and splicings are avoided. a

A further advantage of the pump discharge head and liner shoe arrangement of the invention relates to the flushing of accumulated sand from the liner adjacent the pump discharge head. As best seen in FIG. 4, the pump installation normally resting on shoulder 26 can be lifted by the suspending cable 19, so as to disengage the flange 27 of the pump head from the shoulder 26 of the shoe 25. With the discharge head 28 thus elevated in the liner, accumulated sand may be flushed from around the pump head and downwardly through the central opening in the thickened portion 21, into the well casing 10. Upon completion of this operation, the pump installation is lowered by the cable 19 to its operative position with the flange 27 again engaging the shoulder 26.

If desired, suitable means may be provided for sealing and stabilizing the cable 19 above its connection to the pump installation. For example, as seen in FIG. 2, a seal tube 33 may surround the upper portion of the cable within the liner 14, and a cable seal 34 seals the cable within the tube 33 so as to prevent the loss of pressure where the cable enters the assembly. The tube 33 may be centralized by suitable spiders or the like 35 engaging the interior of the seal tube 33.

The preferred form of the invention herein described is used when suflicient space is available to allow the installation plus the conductors 24 to be inserted through the shoe 25. In this form, the pump 11 is located at the upper end of the installation with the motor 13 at its lower end. In the event that only limited space is available, that is, where the size of the casing 10 limits the diameter size of the liner and shoe, the units of the installation may be reversed so that the motor unit is at the top of the installation and the pump unit is at the bottom. In this case, the conductors 24 would be directly connected to the motor from the splicing chamber 23, and it would be unnecessary to carry the conductors downwardly alongside the installation as in the preferred form.

Referring again to FIGS. 1 and 2, it will be seen that the arrangement illustrated not only provides for the delivery of oil from a well casing through the liner to the surface, but the annulus 16 between the liner and casing provides a means for gas separation to be effected. The gas bubbles up through this annulus and is discharged through ports 17 in the casing head 18, which minimizes the gas content of the fluid being pumped through the liner 14.

Also, as shown in FIG. 1, rubber sand checks 36 may be provided at strategic points in the liner to reduce the accumulation of sand around the pump discharge head.

It will be apparent that this invention affords the advantages of wire-line, suspended pump installations, such as described in Arutunott Pat. No. 3,411,454, but overcomes certain disadvantages of such structures. The conductors of the cable are spliced in a low pressure zone, and thus are not affected by the high pressure resulting from the pump discharge. The pump discharges into the retrievable liner through the shoe which acts as a packer. This olfers the advantage of being able to dump the liner of sand by simply lifting the pump installation through the shoe and eliminates the need to swab the well as with a permanent packer. It also provides for gas separation through the annulus between the liner and the well casinga From the foregoing, it is believed that the invention may be readily understood by those skilled in the art without further description, it being borne in mind that numerous changes may be made in the details disclosed without departing from the spirit of the invention.

We claim:

1. A wire-line, suspended pump installation for a well casing, comprising an electric motor driven pump having a discharge head, a radially projecting annular flange on said head, an electric conductive cable having means for connecting the same to said pump for suspending the latter in said well casing and for energizing the motor of said pump, a retrievable liner extending downwardly in said casing from the earths surface, spacedradially inwardly from the wall of said casing, said liner surrounding said cable and pump discharge head, an inwardly directed annular abutment on said liner underlying said discharge head flange for supporting said pump and positioning the same at a predetermined operative level in said casing, the intake of said pump communicating with the interior of said well casing below said liner, the discharge head of said pump discharging into the interior of said liner above said flange and supporting abutment, means at the junction of said discharge head and liner for sealing the interior of said liner from said casing, the external diameter of said pump installation below said discharge head flange being sufficiently less than the internal diameter of the opening in the annular abutment on said liner to permit the independent bodily withdrawal of said pump installation from said liner by said cable, and the engagement of said pump head flange and liner abutment permitting joint withdrawal of said pump installation and liner from said casing.

Z. An installation as claimed in claim 1, wherein the conductive wires of said cable are spliced to the pump motor conductors in a low pressure zone, isolated from the high pressure zone of said pump discharge.

3. An installation as claimed in claim 1, including a conductor splicing chamber in said liner above said pump discharge head, means sealing said chamber from the interior of said liner, and means for placing the interior of said chamber in communication with the fluid in said casing below said discharge head, whereby the electrical connections and splicings for said installation are all isolated from the high pressure discharge zone of said liner.

4. An installation as claimed in claim 3, wherein said splicing chamber is fixed to and forms a part of said suspended installation, said cable weight-supporting connecting means being at the upper end of said chamber.

5. An installation as claimed in claim 1, wherein said annular discharge head flange rests freely upon the upper portion of said annular liner abutment, whereby said pump installation may be elevated in said liner by said cable to disengage said flange from said abutment to break the seal between said liner and pump discharge head for flushing sand accumulated in said liner around said discharge head past said annular abutment into said casing.

6 A wire-line, suspended pump installation for a well casing, comprising an electric motor driven pump having a discharge head, an electric conductive cable having means for connecting the same to said pump for suspending the latter in said well casing and for energizing the motor of said pump, a retrievable liner extending downwardly in said casing from the earths surface, spaced radially inwardly from the wall of said casing, said liner surrounding said cable and pump discharge head, means associated with said lines for supporting said pump and positioning the same at a predetermined operative level in said casing, the intake of said pump communicating with the interior of said well casing below said liner, the discharge head of said pump discharging into the interior of said liner above said supporting means, means at the junction of said discharge head and liner for sealing the interior of said liner from said casing, and means for splicing said conductive cable to the conductors leading to said pump motor, said splicing means being located above said pump discharge head in a low pressure zone isolated from the high pressure zone created by said pump discharge.

References Cited UNITED STATES PATENTS 2,043,236 6/1935 Conant 415-601 X 2,648,286 8/1953 Bergh 415501X ROBERT M. WALKER, Primary Examiner US. Cl. X.R. 4l5-50l