US3392785A

US3392785A - Retractable packer

Info

Publication number: US3392785A
Application number: US566004A
Authority: US
Inventors: William R King
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-07-18
Filing date: 1966-07-18
Publication date: 1968-07-16
Anticipated expiration: 1985-07-16

Description

July 16, 1968 w. R. KING RETRACTABLE PACKER 2 Sheets-Sheet 1 Filed July 18, 1966 INVEAVTOR JTTORNEY W////am F. ////7 7 Y K illbl July 16, 1968 w. R. KING 3,392,785

RETRACTABLE PACKER Filed July 18, 1966 2 Sheets-Sheet 2,

W////am A. rf/ny INVENTOR.

United States Patent 3,392,785 RETRACTABLE PACKER William R. King, 201 Betty Drive, Longview, Tex. 75601 Filed July 18, 1966, Ser. No. 566,004 9 Claims. (Cl. 166196) This invention relates to apparatus for use in oil wells and the like, and moreparticularly to-well packers of the type which are adapted to be lowered in unexpanded position into a well bore. and then expanded into sealing engagement with a wall of the well bore.

Well packers of the type described are used for various purposes in connection with oil. and gas wells and commonly include a cylindrical sleeve mounted about a mandrel or cylindrical body, which sleeve is made of a resilient material, such as natural or synthetic rubber, and is adapted to be expanded against the side of the well bore in response to longitudinal compression. It is the purpose of the packer to provide a fluid-tight seal across the well bore.

In the past, however, certain difficulties have been attendant upon the use of such type packers. Frequently, the maintenance of a fluid-tight seal across which is likely to be found considerable pressure differentials, such as are often present in wells, requires very tight engagement by the packer with the wall of the well bore. To this purpose, the sleeve of the packer must be made of relatively highly expansible material, but it is found, and particularly at the high pressures prevailing in deep wells, that the resilient material of which the packer is composed tends to creep or extrude through small crevices or spaces, acting much as does a liquid. The shoes ordinarily provided at the top and at the bottom of the sleeve, which are of a diameter sufficiently small to prevent the possibility of their being stuck in the well bore, are usually of little effect in preventing the resilient sleeve material from extending therebeyond as the packeris set.

The afforesaid tendency-of the sleeve-material to flow in the presence .of high pressures'is often referred to as cold-flowing, and presents the likelihood that the seal intended by the packer will fail. Additionally, the effect may prevent the sleeve from being returned to its unexpanded position, if such is desired. Again, the useful life of the sleeve is materially reduced, and attempted removal of the packer from the well will result in a torn or ruptured, and hence unusable, sleeve. Yet again, the aforesaid cold-flowing of-the sleeve material may interfere with or obstruct the action of the particular tool with which the packer is associated.

I Another problem encountered in setting packers in an open (uncased) bore hole, is that in some formations the borehole may have a very irregular wall, and may also be' washed out to a fairly large diameter in proportion to the diameter of the bit, which determines the maximum retracted diameter of the packer. Packers previously used have not usually been expandable to the extent necessary to provide good sealing against such an irregular wall or in such large diameters.

Various proposals have been heretofore made for overcoming one or more of the foregoing difficulties. For example, one such proposal is shown in US. Patent 2,808,889 to Morrisett et al., and another is shown in US. Patent 2,896,724 to Baker. However, these designs have not been totally effective in that they do not insure prevention of cold-flowing, or they utilize relatively complex and expensive devices, or they have relatively short life, or they are of a type which cannot be removed from the well and reused.

Accordingly, it is an object of this invention to provide an improved well packer adapted to maintain a reliable seal across the wall of the well bore.

H 3,392,785 e ted. J y 6, 1968 It is another object of this invention to provide a well packer which is adapted to seal without substantial coldflowing in bore holes of a variety of diameters.

Still another object of the invention is to provide a well packer in which the pressure loading is distributed between two or more elements so that no one element is subjected to all of the differential pressure.

Another object isto provide a well packer which will engage a surrounding .wall with substantially uniform force throughout its length, and which is readily retracted from such engagement. I

Yet anotherobject of theinvention is to provide a packer which can provide a good seal .even in bore holes with irregular wall surfaces or bore holes which are \bwashed outto a diameter substantially larger than the drill it. v

Another object is to provide a longitudinally compressible well packer in which the radial pressure forces are quite high as compared to longitudinal forces, so that tendency to cold flow is substantially reduced.

These and other objects of the invention will be more apparent from the following description and'the accompanying drawings, wherein FIGURE 1 is a longitudinal sectional view of a wel packer constructed in accordance with the present inven- Eion and shown in an unexpanded position within the well ore;

FIGURE 2 is a longitudinal sectionalv view similar to that of FIGURE 1,- but demonstrates the well packer in substantially fully' expanded positionwithin the well FIGURE 3 is an enlarged horizontal cross-section of the well packer of FIGURE 1- taken at line 3-3 of FIG- URE 1;

FIGURE 4 is an enlarged fragmentary view of the gigiglrlel gripping apparatus of the embodiment of FIG- FIGURE 5 is a view similar to FIGURE 1, but showing another embodiment of the invention; and

FIGURE 6 is an enlarged, partly sectional view of one element of the embodiment of FIGURE 5.

In the embodiment of the invention shown in FIG- .URES 1 to 4, the packer comprises a resilient packer longitudinally displaced from the packer sleeve 10, a backup packer 12, also made of resilient material, which is separated from the packer sleeve 10 by a collar 16 or the like.

Where reference herein is made to the wall of the well bore or the bore hole, it is understood to include any wall surrounding the packer, as for example a well caslng.

The packer sleeve 10 is anchored to the collar 16 as by means of the anchoring devices 18. At the other end the packer sleeve 10 is anchored by similar anchoring devices 18 to a shoe or abutment member 20 which is connected, as by means of threads 22, to an upwardly extending hollow mandrel guide 24, which in turn' may be connected to a drill pipe string or the like. Slidingly received within the hollow mandrel guide 24 is the mandrel 26, which extends into the lower portion of the guide 24 and has an upper portion or head 28 slidably positioned in the guide 24. The enlarged head 28 is of such a size as to shoulder on the internal shoulder 30 at the lower end of theguide 24. The mandrel 26 extends downwardly and is slidably received through the shoe 20, the packer sleeve 10, the collar 16 and the back-up packer 12 therebelow. Shoe 20 and collar 16 sealingly engage the mandrel, as by means of the O-rings 31. The mandrel is fastened to a lower shoe or abutment 32 as by means of threads 34. Therebelow a conventional perforated anchofpipe' '36'is Connected to the lower shoe 32.

The packer sleeve is, in this embodiment sealingly connected to the upper shoe and the collar 16, and is slidably positioned upon the mandrel 26. It will be apparent that the packer sleeve and the back-up packer are both compressed, and thereby expanded radially outwardly, by the imposition of longitudinal force by moving the mandrel guide 24 downwardly with respect to the mandrel.

Preferably the packer sleeve 10 is formed in such a manner that, upon expansion outwardly, it will exert substantially uniform pressure upon the wall of the bore hole throughout most of the length of the packer. In a preferred embodiment, as shown in the drawing, the packer sleeve is made hollow by means of an annular cavity 38 which may be filled with oil or other relatively incompressible fluid. The oil may be inserted into the cavity, prior to the installation of the-sleeve on the tool, I

by various means well known in the art, as for example through a conventional check valve illustrated schematically at 39; The annular cavity 38 preferably extends through a major portion of the length of the packer sleeve.

The annular cavity may be in the form of a cylinder, as shown in the drawing, or may be divided into two or more sections, such as toroidal sections, preferably communicating between each other, to provide connections between the outer and inner walls of the packer sleeve. Other shapes of cavities which will give flexibility of movement and will allow transmission of pressures throughout the packer may also be used. The oil or other liquid in the cavity is sealed in, as for example by means of a plug on top of the check valve 39, so that the fluid in the cavity is isolated from surrounding fluids at all times, and the cavity remains closed during use.

The collar 16 is, as shown, connected to the packer sleeve by the anchor members 18, and forms an abutment for the lower end of the packer sleeve. In the embodiment shown, the collar has a cylindrical threaded portion 33, to which a back-up packer insert 35 is threadedly attached. The insert 35 is shown as integral with the back-up packer, and serves to hold the two packer elements together. The lower end of the collar 16 is tubular in form, and extends into a matching counterbore in the upper end of the back-up packer.

The lower or back-up packer 12 is preferably formed around and attached to a cage member 40 which is slidably received on the mandrel 26 just below the lower end of the collar 16. The cage 40, in the embodiment shown, is provided with four circumferentially spaced apertures 42. A toothed slip button 44 is slidingly received in each of these apertures, with downwardly pointed teeth 46 thereon facing toward the mandrel 26. Each button is fastened, as by means of the member 48, to a flexible disc 50, which is of a cupped form to normally hold the teeth 46 of the button away from the mandrel. The disc 50 is adapted, however, to be biassed inwardly upon the application of force thereto, to push the teeth of the button into engagement with the mandrel. The aperures 42 in the cage 40 are vented to the interior of the mandrel through ports 51 formed in the mandrel, so that the pressure between the mandrel and the back-up packer is always substantially the same as the pressure below the well packer. Thus, unless there is a fluid pressure differential across the packer, only the force of engagement of the packer with the surrounding wall determines the amount of expansion of the packer at which the slip buttons are pushed into engagement with the mandrel, and longitudinal compression of the lower packer is thus terminated. At the moment of setting the packer, no fluid pressure differential exists.

Instead of the cage and the toothed slip button, other devices, one example of which is hereinafter described, may be used to provide resilient means to hold the slip teeth away from the mandrel, and to allow the teeth to engage the mandrel at a predetermined pressure of engage ment of the packer with the wall of the bore hole. The cupped disc 50 has the advantage that it can be, and preferably is, designed so that, at a predetermined pressure, it will snap from disengaged position to engaged position.

In use, the apparatus just described is attached to the lower end of a drill string or other tubular support member and lowered until the perforated anchor pipe engages the bottom of the hole. Continued downward force causes longitudinal compression of the packer sleeve 10 and of the lower back-up packer 12 so that these elements expand outwardly. When the back-up packer expands outwardly far enough that it engages the wall 14 of the bore hole, a pressure begins to build up within the resilient material of the packer, such material being natural or synthetic rubber, or the like, as is well known in the art. Eventually this pressure will build up high enough that the radial force created will cause a collapsing of the flexible cup shaped discs 50 so that the teeth 46 0f the buttons 44 are pressed into engagement with the mandrel. This prevents further downward movement of the cage 40, and the abutment of the upper end of the cage by the collar 16 prevents further compaction of the lower back-up packer upon additional downward movement of the drill string. Such further downward movement causes compression of only the upper packer sleeve 10. Due to the liquid carried within the hollow pack-er sleeve 10, pressures outwardly exerted by the packer are substantially uniform throughout a major portion of the length of the packer. In addition, due to the flexibility and pressure transmission resulting from the sealed cavity in the packer sleeve, the ratio of radial force to longitudinal force within the packer sleeve is much greater than with the usual packer, so that the tendency to cold flow longitudinally of the bore hole is substantially reduced.

The expansion of the lower packer member causes this packer member to form a seal and a permanent stop at approximately the position of the collar 16 so that the upper packer member cannot extrude downwardly below this point. Also the use of the lower packer member in this manner causes a distribution of the pressure differential over the packer between the lower packer member and the upper packer member. Undue extrusion and damaging of the lower packer member is prevented by limiting the longitudinal compression of this member to an amount determined by the pressure on it.

When packers are first set, in conducting a subsurface formation test, for example, the pressures above and below the packers are substantially the same. However, in the usual formation test, the pressure below the packer i then greatly reduced by opening a valve to allow formation fluid to flow from the formation to the surface via the drill stem. This creates a pressure differential which, in the usual well, amounts to several thousand pounds per square inch, across the packer. In the packer of the present invention, the removal of the pressure below the backup packer causes this packer to move downwardly a small amount, thereby partially reducing the pressure between the back-up packer and the packer sleeve 10. Thus the pressure differential is divided between the packers.

The release of the pressure below the back-up packer also reduces the pressure in the apertures 42. Thus a pressure differential is created across the back-up packer which assists in maintaining the slip button teeth in engagement with the mandrel, so that the possibility of slippage, due to the longitudinal force of fluid pressure, is reduced.

To remove the packer of this invention, an upward force is exerted upon the mandrel guide. This force first causes a contraction of the packer sleeve 10. Radial contraction is greatly facilitated because of the fact that the annular space between the packer sleeve and the mandrel is sealed from subjection to well fluid pressure Thus as soon as the mandrel guide begins to move upwardly so that the packer sleeve begins to contract, there is a pressure differential on the packer sleeve tending to push it away from the surrounding wall and toward the mandrel. This pressure differential greatly assists in assuring that the packer sleeve is readily separated from the surrounding wall without damage.

Since the packer sleeve and the back-up packer are tied together by the collar 16, further upward movement of the mandrel guide will, of course, relieve the compressive force on the back-up packer so that it can be pulled free of the surrounding wall and the slip buttons be released from their engagement with the mandrel, and the entire tool can be lifted from the well.

In the embodiment of the invention shown in FIG- URES 5 and 6, several modifications are incorporated. In this embodiment the same reference numerals are used as in FIGURES 1 to 4 for the same elements.

In this embodiment slips for engaging the mandrel are carried within the upper packer sleeve 110 instead of the lower packer sleeve 112. In addition, both packer sleeves are provided with

annular cavities

138 and 139, respectively. Furthermore, the mandrel engaging slip device is embodied within a single element 144.

As in the embodiment previously described, the upper packer sleeve 110 is sealingly connected to the shoe 20 and the collar 11-6. The collar 116 differs from the collar 16 of the previous embodiment in that it is provided with threaded means 141 to which the flexible slip device 144 may be engaged. This device comprises, as better seen in FIGURE 6, a generally cylindrical member having upwardly extending resiliently flexible fingers 150, such fingers being provided by the cutting of longitudinally extending slots 149 therein. The inner circumferential faces of the fingers 150 are provided with inwardly extending slip teeth 146, which are proportional to engage the mandrel 26 upon being biased radially inwardly, and are directed so that upon such engagement they will resist downward movement of the slip device 144 with respect to the mandrel.

It will be apparent that this embodiment of the invention :operates similarly as the one previously described. When the perforated anchor'pipe engages the bottom of the hole, downward force upon the drill string causes longitudinal compression of the packer sleeve 110 and the lower packer 112, so that these elements expand outwardly. In this embodiment, when the upper packer sleeve expands outwardly far enough that it engages the wall 14 of the borehole, pressure builds up within the material of the packer, including the liquid carried within the annulus 138, until such pressure is high enough that the radial force create-d will bend the fingers 150 inwardly to engage the teeth 146 with the mandrel 26. Such engagement of these teeth with the mandrel provides a substantial resistance to further downward movement of the collar 16 and thereby provides a substantial resistance to further compression 'of the lower packer 112. Any further downward movement causes compression of only the upper packer sleeve 110.

In this embodiment of the invention, the fluid-filled cavity in each packer sleeve serves to improve the uniformity of forces upon each packer sleeve, so as to spread out the load carried by the packer. The desired pressure differential across the upper packer to improve the gripping of the teeth 146 on the mandrel 26 is provided by the ports 151 extending from the interior of the mandrel into the area in which the slip device 144 is carried.

Many variations of the embodiments hereinbefore described will be apparent to those skilled in the art. For example, one or more of the variations shown in FIG- URES 5 and 6 might be substituted in the embodiment shown in FIGURES l to 4 inclusive. It will be apparent that substitution of these or other equivalents, however, would accomplish the same purpose and would, therefore, be included in the invention. The invention is, therefore, not limited to the embodiments shown and described herein, but only as set forth by the appended claims.

I claim:

1. A well packer comprising a resilient and radially expansible packer sleeve,

means for applying a force to said packer sleeve to cause it to expand radially outwardly into engagement with a surrounding wall,

means connected to said packer sleeve and engageable with a second means and actuable by a predetermined degree of force of engagement of said packer sleeve with said surrounding wall to resist further radial expansion of said packer sleeve.

2. A well packer as defined tby claim 1 and including a mandrel extending longitudinally within said packer sleeve,

said means for applying a force to said packer sleeve comprising means movable longitudinally with respect to said mandrel.

3. A well packer as defined by claim 2 wherein the means actuable to resist radial expansion comprises slip means carried within a packer sleeve with its teeth facing said mandrel,

and resilient means attached to said slip means adapted to be biassed to move said slip means radially inwardly to engage the teeth with the mandrel in response to radially inward force resulting from the engagement of the packer sleeve carrying said slip means with the surrounding wall.

4. A well packer comprising a mandrel,

a resilient and expansible packer sleeve around said mandrel,

a second resilient and expansible packer sleeve around said mandrel adjacent an end of the first packer sleeve,

means for applying a force to said second packer sleeve to cause it to expand radially outwardly into engagement with a surrounding wall, and

means connected to said second packer sleeve adapted to be actuated to resist such radial expansion upon attainment of a desired resistance against expansion.

5. A well packer as defined by claim 4 wherein the means for applying a force to said second packer sleeve comprises means movable longitudinally to longitudinally compress and radially expand said second packer sleeve,

and the means actuable to stop radial expansion comprises slip means carried with one sleeve with its teeth facing said mandrel,

and resilient means attached to said slip means adapted to be biassed to move said slip means radially inwardly to engage the teeth with the mandrel in response to radially inward fonce resulting from the engagement of the packer sleeve with the surrounding wall.

6. A well packer for sealingly engaging the surrounding wall of a bore hole, comprising a longitudinally extending mandrel,

a resilient and expansible packer sleeve around said mandrel,

a resilient and expansible back-up packer around said mandrel adjacent the lower end of said packer sleeve,

an abutment on the lower end of the mandrel engaging the lower end of the back-up packer,

means extending downwardly from the mandrel to engage the bottom of the bore hole,

an upper abutment slidably received on said mandrel engaging the upper end of said packer sleeve,

means on the upper abutment for engagement by a well pipe,

a collar slidably mounted on said mandrel intermediate said packer sleeve and said back-up packer, and means on said back-up packer actuable in response to the force of engagement of said back-up packer with the surrounding wall to stop radial expansion of said back-up packer,

7 whereby when said well packer is positioned in a bore hole with the downwardly extending means engaging the bottom, downward movement of said well pipe will cause longitudinal compression and radial expansion of said back-up packer until the force of its engagement with the wall of the bore hole is sufficient to actuate the last-named means. 7. A well packer as defined by claim 6, wherein the means actuable to stop radial expansion comprises slip means carried within the back-up packer with its teeth facing said mandrel, and resilient means attached to said slip means adapted to be biassed to move said slip means radially inwardly to engage the teeth with the mandrel in response to radially inward force resulting from the engagement of the back-up packer with the surrounding Wall. 8. A well packer for sealingly engaging the surrounding wall of a bore hole, comprising a longitudinally extending mandrel, a resilient and expansible packer sleeve on said mandrel, a second resilient and expansible packer sleeve on said mandrel adjacent the lower end of said packer sleeve, an annular cavity in at least one of said packer sleeves substantially filled with a substantially incompressible fluid, means for applying a force to said packer sleeves to cause them to expand radially outwardly into engagement with the surrounding wall, and means connected to said second packer sleeve adapted to be actuated to resist further radial expane sion of the second packer sleeve upon attainment of a desired resistance against radial expansion.

9. A Well packer comprising a tubular mandrel a resilient and radially expansible packer sleeve on said mandrel,

means movable longitudinally with respect to said mandrel adapted to apply a longitudinal force to said packer sleeve to compress it longitudinally and expand it radially,

slip means connected to said packer sleeve adapted to be actuated to stop such radial expansion upon attainment of a predetermined resistance against further expansion,

and a port communicating between the slip means and the interior of said mandrel to maintain said slip means at the same pressure as the interior of said mandrel.

References Cited UNITED STATES PATENTS 1,810,352 6/1931 HumasOn 277 2,233,013 2/1941 Humason et al. 166-196 2,606,618 8/1952 Page 166-496 2,713,907 7/1955 Kline et al. 166196 2,814,514 11/1957 Beatty 277226 JAMES A. LEPPINK, Primary Examiner.

Claims

1. A WELL PACKER COMPRISING A RESILIENT AND RADIALLY EXPANSIBLE PACKER SLEEVE, MEANS FOR APPLYING A FORCE TO SAID PACKER SLEEVE TO CAUSE IT TO EXPAND RADIALLY OUTWARDLY INTO ENGAGEMENT WITH A SURROUNDING WALL, MEANS CONNECTED TO SAID PACKER SLEEVE AND ENGAGEABLE WITH A SECOND MEANS AND ACTUABLE BY A PREDETERMINED DEGREE OF FORCE OF ENGAGEMENT OF SAID PACKET SLEEVE WITH SAID SURROUNDING WALL TO RESIST FURTHER RADIAL EXPANSION OF SAID PACKER SLEEVE.