Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3422899 A
Publication typeGrant
Publication dateJan 21, 1969
Filing dateNov 9, 1966
Priority dateNov 6, 1966
Publication numberUS 3422899 A, US 3422899A, US-A-3422899, US3422899 A, US3422899A
InventorsBrown Cicero C
Original AssigneeBrown Cicero C
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Well packer
US 3422899 A
Abstract  available in
Images(3)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Jap. 21, 1969' C. @BROWN 3,422,899

WELL PACKER Jan. 21, 1969 C. c, BRQWN 3,422,899

WELL PACKER Filed Nov. 9, 1966 Shee'fI 2 of 5 g i Y 2. ZAM.,

AJam. 2l, 1969 c. c. BROWN l 3,422,899

WELL PACKER Filed'Nov. 9, 1966 sheet a of s C/GERO (I ROW/V u INVENTR.

United States Patent O 3,422,899 WELL PACKER Cicero C. Brown, 8490 Katy Road, Houston, Tex. 77024 Filed Nov. 9, 1966, Ser. No. 593,009 U.S. Cl. 166-129 Int. Cl. E21b 23/06 17 Claims ABSTRACT F THE DISCLOSURE A well `packer having a tubular support, `a packing assembly releasably connected to the tubular support and The present invention relates t-o an improved well packer adapted for use in a well bore.

An object of the present invention is to provide an improved well packer which can be set in a well bore and includes a by-pass of the packing assembly which may 'be opened and closed without unsetting the packing assembly.

Another object of the present invention is to yprovide an improved well packer with a by-pass of the packing assembly which may be opened 4or closed and when closed, the uid pressure forces are used to maintain the set position of the well packer.

A further object is to provide an improved well packer which may be set, lunset and reset within a well bore without rotation of the well string Aon which the packer is mounted.

Another object is to provide an improved well packer which utilizes pressure differentials to maintain the set position of the well packer and can be easily released from set position and reset at another position Within a well bore.

A further object is to provide an improved well packer which is weight set and remains set with a minimum of tubing weight `on the packer regardless of the pressure differentials to which the packer is exposed.

A still further object is to provide a well `packer with a piston controlled by-pass having a sealing assembly adapted to seal against the piston and which, because it is protected from exposure to well fluids, has a greatly extended life.

Another object is to provide an improved well packer having an anchoring assembly whichy is held in unset position during running by releasable engagement with the tubular support of the well packer.

These and other lobjects and advantages of the present invention are hereinafter set `forth and explained in the following specification wherein the preferred form of the well packer as shown in the drawings is described and wherein:

FIGURES 1A and 1B are detailed partial longitudinal sectional lviews of the preferred form of well packer of the present invention. FIGURE 1B is the lower continuation of FIGURE 1A.

FIGURE 2 is a similar sectional view showing the well 4packer as it is run into a well bore.

FIGURE `3 is another similar sectional view of the well packer after the tubing has been raised to accomplish release of the anchoring assembly from the tubular support.

FIGURE 4 illustrates the Well packer in set position with the by-pass closed.

3,422,899 Patented Jan. 21, 1969 ICC FIGURE 5 illustrates the well packer in set position with the by-pass open.

FIGURE 6 is a transverse sectional view of the holddown assembly taken along line 6 6 in FIGURE 1A.

FIGURE 7 is a transverse sectional view of the packing assembly taken along line 7 7 in FIGURE 1A and showing the details of the latching dogs.

FIGURE 8 is a transverse sectional view of the anchoring assembly taken along line 8 8 in FIGURE 1B.

As illustrated in FIGURES lA, 1B and 2, the well paoker is run into a well bore, such as within the casing C, supported by the tubing string T. The well packer includes the upper hold-down assembly H, the packing assembly P, the anchoring assembly A and the release means R, all mounted around and supported on tubular support 10l as hereinafter described.

Tubular support 10 is suitably connected to the tubing string T by the ycoupling 12 and forms an extension thereof. The tubular support 10 is provided with three external shoulders, the downwardly facing shoulder 14, the upwardly facing shoulder 16 and the lower downwardly facing shoulder 18, and snap rings 20y and 22 to operably support the assemblies of the well packer thereon. The lower end of tubular support 10 is connected to the lower extension of tubing string T by the collar 24 and the coupling 26. The collar 2,4 defines the 1upwardly facing Ashoulder 2,8 normally supporting the releasing means R.

The hold-down assembly H includes the body 30 which surrounds and is slidable on tubular support 1l). Pressure responsive grip-ping means, such as, gripping buttons 32, are positioned within recesses in body 30 and are biased inwardly by the springs 34 which are supported by the strips 36 mounted on the exterior of body 30, each of the strips 36 spanning one of the Ibutton recesses. The interior of 'body 30y in cooperation with the exterior of tubular support 10 defines a communication from below the body to the inner surface of the gripping buttons 32. The gripping buttons 32 are sealed against the interior of the recesses in which they are mounted so that they move radially outward into gripping position responsive to the pressure of fluids on their inner surface.

The upper portion of the interior surface of body 30 includes seals, such as, O-rings 38, to provide a seal against the exterior of tubular support 10. The lower interior of body 30 denes the cylinder 40 in which balance piston 42 is positioned. Body 30 is slidable on tubular support 10 between coupling 12 and piston 42. Balance piston 42 is annular in shape and is secured to the exterior of tubular support 10 by the snap rings 20 and 22. The exterior of balance piston 42 is sealed against cylinder 40. Balance piston 42 defines a restricted passageway 44 which cornmunicates through the head 46 of piston 42 to the inner surface of gripping buttons 32. The depending skirt 48 of said balancing piston 42 is spaced from both the exterior of tubular support 10 and the wall of cylinder 40. The piston 42 functions as a means of closing the packing assembly by-pass, a means directing pressure from below the packing assembly P when set, to the gripping buttons 32 and a means providing a balancing force downward to offset the pressure force on the tubing string, as hereinafter more fully explained.

The packing assembly P surrounds the tubular support at a position below and spaced from the hold-down assembly H. The packing assembly P includes the packing sleeve 50, the upper end of which is connected to the upper abutment ring 52 as shown; the packing element 54 which may take any desired form surrounding the sleeve 50, such as, the dual elements separated by the packing follower as shown in FIGURE lA or a single packing element as shown in FIGURES 2, 3, 4 and 5; a lower abutment ring 56; and the means 58 for releasably connecting the packing assembly P to the tubular support 10. The packing sleeve 50 supports the ring 56 on its shoulder 60 when the packing element 54 is relaxed. Movement of abutment ring 56 toward abutment ring 52 compresses the packing element 54 longitudinally and forces it radially outward into sealing engagement with the interior surface of casing C. Expander cone 62 is connected to the ring 56 and is adapted to set the anchoring assembly A as hereinafter explained. The upper interior surface 64 of expander cone 62 is tapered downwardly and inwardly to provide a camming release of the means 58. The shoulder 66 on the interior of expander cone 62 supports one end of spring 68. The spring 68 also engages the lower end of packing sleeve 50 to urge expander cone 62 and abutment ring 56 downwardly with respect to sleeve 50. Both packing sleeve 50 and expander cone 62 are provided with passages therethrough to assure that the by-pass around packing assembly P is not blocked or restricted by the seating of the lower end of packing sleeve 50 on the shoulder 16 and by the engagement of the expander with the anchoring assembly A.

The upper end of packing sleeve 50 is extended by the rings 70 and 72 as shown in FIGURE 1A but is, for purpose of clarity, shown in the remainder of the figures to be a single sleeve of similar configuration, The ring 70 defines the upwardly facing shoulder 74. The packing seal 76 is positioned in an interior recess in ring 72 and the packing protector 78 is movably positioned within the rings 70 and 72, surrounding the tubular support 10 and is normally urged by the spring 80 which is supported on shoulder 74 into sealing engagement with the packing seal 76. It should be noted that the entire packing assembly P is spaced from the exterior of the tubular support to provide the by-pass passage 82 which cornmunicates across the packing assembly P. The upper edge of protector 78 denes the slots 84 and the lower edge of body 30 defines the slots 31 which allow opening of the by-pass around the packing assembly P when the packing assembly is set as hereinafter explained.

The connecting means 58 includes, in the preferred form best shown in FIGURE 7, three dogs 86 pivotally positioned in windows in packing sleeve 50 by the pins 88 and having their upper edges urged inwardly by the springs 90. In running position as shown in FIGURE 1A, the upper inner edge of dogs 86 engages the shoulder 14 to hold the packing assembly P in its desired position on tubular support 10.

When the well packer is run into the well casing C, the by-pass 82 is open allowing fluids in the well to flow therethrough and around the exterior of the packing assembly to increase the speed at which the well packer may be run into the desired position in the well casing C. As the packing assembly P is set, the lower outer edge of dogs 86, by engagement with the surface 64 on the expander cone 62, causes the dogs to be pivoted so that they clear shoulder 14. With the dogs in this position, the tubular support 10 is free to move downwardly through the packing assembly P whereby setting is accomplished. The engagement of the lower end of sleeve 50 on the shoulder 16 supports the packing assembly P on the tubular support 10.

The anchoring assembly A includes the body 92 in which are mounted a plurality of friction means, such as the spring loaded wiper blocks 94, and the gripping elements 96 which are connected to the body 92 by the usual T slot connections so that the gripping elements 96 may be urged outwardly into pipe gripping position by the expander cone 62. Means such as springs 98 are provided to normally urge the gripping elements 96 inwardly to maintain the engagement between the shoulder 100 on the interior of gripping elements 96 with the shoulder 18 on tubular support 10 and thus maintain the anchoring assembly A in running position until released for setting.

The illustrated releasing means R which is adapted to coact with the anchoring assembly A to release it from its running position is a sleeve 102 surrounding and slidable on the lower end of tubular support 10 and supported in running position on the shoulder 28 of collar 24. The upper end of the sleeve 102 is enlarged to have substantially the same outer diameter as the shoulder 18. The exterior of sleeve 102 is tapered from such enlargement downwardly and inwardly to the outer diameter of the remainder of sleeve 102.

Release of the anchoring assembly A is laccomplished by lifting the tubing string to move the sleeve 102 through the anchoring assembly A to the position illustrated in FIGURE 3. 'Upward movement of tubular support 10 does not move anchoring assembly A upward since it is held in position by the frictional engagement of the wiper blocks 94 with the interior of casing C. Once the upper enlargement on sleeve 102 has passed through the shoulder on gripping elements 96, the anchoring assembly A is released and may be set by lowering the tubing string T. During lowering, -shoulder 18 engages the upper end of sleeve 102 and moves the enlarged portion of sleeve 102 through the shoulder 100 on gripping elements 96. The taper on sleeve 102 moves the gripping elements 96 outwardly so that shoulder 18 readily passes therethrough. Once the shoulder 18 has passed through the shoulder 100 on the gripping elements 96, the sleeve 102 is free to slide downwardly on the tubular support 10 and stops when it engages the shoulder 28 on collar 24. The engagement of the shoulder 100 with the taper on sleeve 102 also functions to hold the sleeve 102 in engagement with the shoulder 18 until sleeve 102 is forced therethrough by shoulder 18.

In operation, the well packer is run into a well bore on the tubing string T with the various components and assemblies positioned as illustrated in FIGURES 1A, 1B and 2; FIGURE 2 being substantially similar but showing the complete structure in one view for ease of comparison with FIGURES 3, 4 and 5.

When the well packer is positioned at the desired level in the well casing C for setting, the anchoring assembly A is iirst released by lifting the tubing string T as hereinbefore described. Thereafter the tubing string T is lowered and the expander cone `62 engages the inner tapered surfaces of the gripping elements 96 to urge them outwardly into pipe gripping engagement with the interior of casing C.- The wiper blocks 94 provide suicient resistance to the movement of the anchoring assembly A during this action to assure that the gripping elements 96 are set -by the expander cone 62. The resistance offered to the movement of the expander cone 62 on the inner surface of the gripping elements 96 moves the packing sleeve 50 and dogs 86 downwardly with respect to the expander cone 62 and the inner surface 64 engages the dogs 8-6 to pivot them out of engagement with the shoulder 14.

The continued lowering of the tubing string then. is relatively free until the hold-down assembly H comes into contact with the packing assembly P. The lower end of the Ibody 30 contacts the upper end of packing sleeve 50 `at approximately the same time that the lower end of the skirt of balance piston 42 contacts the upper edge of the packing protector 78. Since the body 30 is free to slide a short distance with respect to the tubular support 10, the skirt 48 first moves the packing protector 78 down and as it does so, it moves into engagement with packing seal 76 to close the communication of the by-pass passage 82 with the exterior portion of the well packer and provides communication to the gripping buttons 32 through the restricted passageway 44. With further downward movement of the tubing string T, the coupling 12 engages `body 30 and forces it and sleeve 50 downwardly to thereby set the packing element 54 yby moving the upper abutment downwardly while the lower abutment is held against downward movement by the gripping elements 96. Thus, the well packer is in set position as illustrated in FIGURE 4 with the by-pass passage closed and com munication esta-blished from below the packing assembly P tothe gripping buttons 32.

In this set position, a greater pressure below the packing element 54 than above is exerted through the by-pass passage 82, the restricted passageway 44 to the inner surface of the gripping buttons 32 and to the upper surface of the head 46 of the balance piston 42. This pressure urges the gripping buttons 32 outwardly into gripping engagement with the interior of casing C to prevent movement of the well packer upwardly and also by virtue of the greater area of the upper surface of head 46, exerts a force downwardly which is preferred to be at least equal to the pressure force exerted upwardly on the balance piston 42 and on the tubular support 10. This balancing of the pressure forces by balance piston 42 and the holding of the gripping elements 32 eliminates the need for having excessive tubing weight exerted on the Well packer to maintain its set position.

When the pressure above the packing element 54 is greater than the pressure below, this pressure is exerted against the element 54 to tend to set it tighter against the interior of casing C and also is transmitted to expander cone 62 to wedge it tighter against the interior ofgripping elements 96. It should be noted that the teeth on gripping element-s 96 are faced in a downwardly direction so that they resist any downward movement when set against the casing C. Therefore, the well packer of the present invention when set, remains in set position when exposed to pressure differentials and utilizes such pressure differentials to maintain the set position.

In many installations, it is desired to be able to open a by-pass around a well packer while the packer remains set. This is readily accomplished in the well packer of the present invention by lifting the tubing string T only a sufficient distance to position the balance piston 42 against the upper end of the cylinder 40 in the body 30. In this position, the skirt 48 of the balance piston 42 is withdrawn from engagement with the packing seal 76 and yat the same time, the packing protector 78 is urged upwardly by the spring 80 to engage the packing seal 7'6 and maintain engagement with the lower end of skirt 48. Since piston skirt 48 and the lower edge of body 30 are provided with slots, the by-pass is opened to communicate to the exterior of the well packer above the packing element 54. This opening of the by-pass is clearly illustrated in `FIGURE 5 and the ow of fluids from below the packing element 54 is shown by the arrows. When the by-pass has ben opened with the packing element 54 in set position, the pressures thereacross are equalized and there are no forces tending to unset the packing element or the gripping members. During the lifting of the tubing string T to open the by-pass, the set position is maintained by the pressure on the inner surface of the gripping buttons 32 until the by-pass is fully opened.

With the well packer in set position, it is released by lifting the tubing string T. The initial portion of the upward movement of tubular support opens the by-pass as hereinbefore described, to equalize ud pressure across packing element 54. Continued lifting moves the shoulder 16 into engagement with the lower edge of packing sleeve 50 and lifts sleeve 50 to remove the upper abutment from supporting the longitudinal compression of packing element 54. Additionally, the spring 68 exerts a force on the packing sleeve 50 tending to move it upwardly with respect to expander cone 62. Further upward movement causes shoulder 60 on packing sleeve 50 to engage and pull expander cone 62 out from under the gripping elements 96. When sleeve 50 picks up expander cone 62, the lower edge of dogs 86 are free from contact with surface 64 and are urged inwardly to engage shoulder 14. Upon the removal of expander cone 62 from under gripping elements 96, the springs 98 cause the gripping elements 96 to retract so that shoulders 100 are positioned to engage shoulder 18 on tubular support 10. Thus, the

well packer has been returned to the position illustrated in FIGURE 2. If it is desired to lower the well packer in the well bore, it may be done by lowering the tubing string T. The well packer can then be set at any desired level in accordance with the setting procedure previously described. If it is desired to set the well packer at a higher level or to pull it from the well bore, the tubing string T is raised and the well packer assumes the position illustrated in FIGURE 3, with the release sleeve 102 within the anchoring assembly A. The well packer may be set from such position by lowering the tubing string T when the well packer is positioned at the desired level. It sets as previously set forth since the anchoring assembly A has been moved to a position for setting.

From the foregoing it may be seen that the improved well packer of the present invention is readily run into a well bore, set, unset and moved to another position for setting. The well packer also includes provision for the opening and closing of the by-pass around the packing assembly and for communicating fluid pressure below the packing element to the hold-down gripping elements when the by-pass is closed. Further the balance piston by exposing a greater head area to uid pressure, provides a balancing force to offset pressure forces on the tubing and the lower side of the balance piston resulting from the fluid pressures below the packing assembly and thereby eliminates the necessity of maintaining substantial tubing weight on the well packer to hold its set position.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, andY various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. A well packer, comprising a tubular support,

a packing assembly mounted on said tubular support and including a packing element positioned between an upper abutment and an expander cone,

means releasably connecting said packing assembly to Said tubular support,

an anchoring assembly mounted on said tubular support and including gripping elements and friction means,

means on sa-id gripping elements for releasably engaging said tubular support,

means for releasing said gripping elements from engagement with said tubular support responsive to a longitudinal reciprocation of said tubular support, and

means mounted on said tubular support and adapted to engage said upper 4abutment on said packing assembly after said gripping elements are disengaged from said tubular support whereby said expander -cone moves with said tubular support to engage and set said gripping elements and said packing element is compressed into set Iposition between said upper -abutment and said expander.

2. A well packer according to claim 1, wherein said releasable engaging means includes an external shoulder on said tubular support, and

lan internal shoulder on said gripping elements adapted to normally engage said external shoulder on said tubular support.

3. A well packer according to claim 2, wherein said releasing means includes a sleeve slidably mounted on said tubular support, and

means on said tubular support for moving said release sleeve into engagement with said gripping elements to disengage said internal shoulder on said gripping elements from said external shoulder on said tubular support.

4. A well packer according to claim 1, wherein said connecting means includes moving means includes a tapered surface on said expander cone engaging said dog during setting to move said dog out of engagement with said external shoulder.

6. A well packer, comprising a tubular support,

a packing assembly surrounding said tubular support and spaced therefrom to dene a by-pass passage,

means releasably connecting said packing assembly to said tubular support,

an anchoring assembly mounted on said tubular support and having gripping elements adapted to be moved outwardly into pipe-gripping position responsive to a lowering of said tubular support,

releasable means preventing the setting of said anchoring assembly, and adapted to release responsive to a lifting of said tubular support, and

holddown means secured to said tubular support and adapted to close said by-pass passage responsive to a lowering of the tubular support after said packing assembly and said anchoring assembly are set whereby said holddown means is actuated responsive to the pressure in said by-pass passage when said by-pass passage is closed.

7. A well packer according to claim 6, wherein said means closing said by-pass'passage includes a piston surrounding and connected to said tubular support, and

a packing seal surrounding one end of said by-pass passage,

said piston adapted to engage said packing seal in sealed relationshipv responsive to longitudinal movement of said tubular support after said packing and anchoring assemblies have been set.

8. A well packer according to claim 7, including a protector slidably mounted to sealingly engage said packing seal, and

means resiliently urging said protector into engagement with said packing seal whereby said packing seal is protected from well fluids.

9. A well packer according to claim 6,- including a gripping button assembly mounted on said tubular support and having gripping buttons adapted to move radially outward into gripping position responsive to uid pressure on the inner surface of said buttons,

said means closing said by-pass passage defines a passage to provide communication from said by-pass passage to the inner surface of said buttons whereby said buttons are exposed to and actuated by the fluid pressure from the side of said packingassembly opposite to said gripping button assembly.

10. A well packer according to claim 6, wherein said holddown means closing said by-pass passage defines slots whereby lifting of said holddown by sa-id tubular support opens said by-pass passage through said slots while maintaining said packing and anchoring assemblies in set position.

11. A well packer according to claim 9, wherein said means closing said by-pass passage includes an annular piston, and

an internal packing seal supported on the interior of said packing assembly surrounding said by-pass passage,

said annular piston having a head portion and a depending skirt portion,

the depending skirt portion of said piston adapted to engage and seal in said internal packing seal.

12. A well packer according to claim 11, wherein said head of said piston denes a passage to provide the communication between said by-pass passage to said gripping buttons.

13. A well packer according to claim 11, wherein the outer diameter of said head portion of said piston being larger than the outer diameter of said depending skirt portion whereby when said piston is in` position closing said by-pass passage, the pressure force on said head of said piston more than balances pressure forces on said piston and said tubular support to maintain the set position of said packing and anchoring assemblies.

14. A well packer, comprising a tubular support having an upper and a lower external shoulder,

a packing assembly having a packing element positioned between an upper abutment and a lower expander cone,

means releasably connecting said packing assembly to said upper shoulder on said tubular support,

an an-choring assembly including gripping elements and friction means,

said gripping elements releasably engaging said lower shoulder on said tubular support, and

means releasing said gripping elements from said lower shoulder responsive to a lifting land lowering of said tubular support,

the lowering of said tubular support after release of said gripping elements moving said expander cone under said gripping elements to set them in pipegripping position and to'move said upper abutment down to set said packing element between said expander cone and said upper abutment.

15. A well packer according to claim 14, including a 'hold-down button assembly secured to and surrounding said tubular support above said packing assembly and having gripping buttons adapted to move to gripping position responsive to fluid pressure to resist upward movement of said tubular support,

said packing assembly defining a by-pass passage communicating from below to above said packing element, and

means associated with said hold-down assembly adapted to close said by-pass passage when said anchoring and packing assembli'esare set and to provide communication from said by-pass passage to said gripping buttons whereby said gripping buttons are moved to gripping position when the fluid pressure below said packing exceeds the fluid pressure above said passage.

16. A Well packer according to claim 15, wherein said means closing said by-pass passage also is adapted to open said by-pass passage without unsetting said anchoring and packing assemblies.

17,A well packer according to claim 15, wherein said by-pass closing means, whenA closed, exerts a downward pressure force on said tubular support greater than the upward pressure force on said tubular support.

References Cited UNITED STATES PATENTS JAMES A. LEPPINK, Primary Examiner.

U.S. Cl. X.R.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US881154 *Mar 7, 1907Mar 10, 1908Lawrence E RobinsonWell-packer.
US2765853 *Apr 7, 1952Oct 9, 1956Brown Cicero CWell packer
US3101783 *Oct 28, 1960Aug 27, 1963Baker Oil Tools IncWell packer
US3253656 *Aug 5, 1963May 31, 1966Brown Oil ToolsStraight-set retrievable packer
US3329210 *May 5, 1966Jul 4, 1967Brown Oil ToolsRetrievable well packer
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3603388 *Feb 4, 1970Sep 7, 1971Camco IncRetrievable well packer
US3785436 *Jun 23, 1972Jan 15, 1974Davis PWell packer
US4628997 *Jun 22, 1984Dec 16, 1986Hughes Tool CompanyPackoff
US5070941 *Aug 30, 1990Dec 10, 1991Otis Engineering CorporationDownhole force generator
US5819846 *Oct 1, 1996Oct 13, 1998Bolt, Jr.; Donald B.Bridge plug
US7000697Nov 19, 2001Feb 21, 2006Schlumberger Technology CorporationDownhole measurement apparatus and technique
US7040402Feb 26, 2003May 9, 2006Schlumberger Technology Corp.Instrumented packer
Classifications
U.S. Classification166/129, 166/138
International ClassificationE21B33/12, E21B33/129
Cooperative ClassificationE21B33/1294
European ClassificationE21B33/129N
Legal Events
DateCodeEventDescription
Apr 5, 1982ASAssignment
Owner name: HUGHES TOOL COMPANY A CORP. OF DE
Free format text: MERGER;ASSIGNOR:BROWN OIL TOOLS, INC. A TX CORP.;REEL/FRAME:003967/0348
Effective date: 19811214