US2780294A - Packer assembly - Google Patents

Description

G. L. LOOMIS PACKER ASSEMBLY Feb. 5, 1957 2 Sheets-Sheet l Filed May 2, 1955 -1 IUM INVENTOR lenz'zL.L oom z's www ATTORNEYS Feb. 5, 1957 G. L. LooMls 2,780,294

PACKER SSSSSS LY United States Patent O Jr., one-twelfth to W. F. King, and one-eighth to the estate ofFlorence L. Stahl, deceased.

Application-May 2, 1955,- Seriall No. 505,133

2 Claims. (Cl. 166-203) The present invention relates to a packerassembly 1ncluding a packing made of an inert substantially rigid material fory use in a conned closure such as in a strlng of casings or low tubing in oil wells or the like. More particularly, the present invention relates t-o a packer assembly having a packing which may be set xn a deep oil well or the like and which may then be Withdrawn when the necessity arises and reused.

TheV present application is a continuation-in-part of my co-pending United States application, Serial No. 383,577, ined october' 1, 1953-, now abandoned.

In the prior art, packers for use in oil wells or the like usually included a sleeve-type packing made ot' rubber or similar resilient vdeformable compositions and materials. These types of packin-gs have ybeen used in varions stages of drilling in an oil well by expanding them into sealingA engagement with a casing and providing a seal between the' casing and a packer head. Also, packers have been used with packings made of malleable lead Isleeves which arepressed or deformed into sealing engagement with the wall of a casing by `the weight of the well ow tubing on which they are mounted or by some other suitable means.

In the present-day drilling of oil wells and the like, the wells may often go into-the ground to depths of 15,000 to 20,000 feet where very yhigh pressures up to approximately` 20,000 p. s. i. and temperatures up to approximately 400 F. are encountered. Ditii-culties arise in the use of a rubberV or composition type ot packings in a packer assembly in that the rubber or composition cannot withstand the high pressures utilized or encountered 1n modern-day drilling, nor, can they withstand the high temperatures now experienced. Under certain pressure and temperature conditions, the rubber or composltron packing will have a tendency to adhere or vulcamze to the casing wall or will extrude past the packer head. Consequently, it is almost impossible to maintain a good seal `or to remove such` a packing from 4the well, and it it is removed further use of the packing is impossible.

Therefore, an 4object of the present invention is `to provide a packer Iassembly for use in- `deep wells or the like and having a packing which can withstand high temperature and pressure conditions throughout its continuous use in the well.

Another object `of the present invention is to provide a packer assembly for use in deep wells having a packing made from an inert material which is substantially rigid at temperatures andpressures encountered in the well.

Further, an object of the present invention is to provide a packer assembly having a packing made of a metal or alloy whichmay be set in a casing or the like and, when the necessity arises, may be retracted and withdrawn from the casing and reused.v Various types of lead sleeves have been used-in the past as packings for packer assemblies, but these packer assemblies are not retrievable once the packings have been expanded in the well casing as they will not regain their original shape for removal.

Still another object of the present invention is to pro'- vide a packer assembly having a synthetic resin packing 2,780,294 Patented Feb. 5, 1957 for use in deep wells or the'like-which can withstand high temperature and pressure conditions throughout its continuous use in the well.

A still further object of the present invention is to provide a packer assembly which will not be deteriorated by chemicals used in the dri-lling mud. Ancillary to the preceding object, it is also an object of the present invention to provide a packing for a packer assembly which will not be deteriorated by the high temperatures found in deep wells nor will extrude past the packer head due to the extreme pressure within the well. By having the packer assembly and its associated parts made entirely of metal, metal alloys, and synthetic resins or the like, temperature and pressure conditions are not critical to its use as a fluid-tight seal.

A still further object of `the present invention is to provide a packer assembly which will have greater annularclearance between it and the outer well casing, thereby facilitating the entry `and removal of the assembly into the casing.

These and other objects of the invention will appear more clearly in the specication, claims and drawings in which:

Figure 1 is an elevational View partly in section of the metal, metal alloy, or synthetic resin, e. g., Teflon, packing and disclosing the packer assembly positioned in a casing with the packing in the retracted non-sealing position;

Figure 2 is a view of -the packer assembly in the casing taken 'on the line 2 2 of Figure l;

Figure 3 is an elevational view -of the packer assembly partially in section similar -to Figure l 'but showing the packing in the expanded and sealing position;

Figure 4 is a View similar to Figure 2 but taken on the line 4-4 of Figure 3, the mandrel and well flow tubing having been omitted for the purpose of clarity;

Figure 5 is a perspective View of two of the arcuate segments of the packing a-s viewed toward their interior;

Figure`6 is a perspective view of two of the segments of the packing as viewed toward their exterior; and

Figure 7 is a cross sectional view of one of the segmentsof thev packing taken on the line 7-7 of Figure 5.

Referring specifically to the drawings wherein like character or reference numerals represent like or similar parts, the present invention includes a packer assembly generally designated by the numeral 10, the packer assembly being adapted to be lowered into a casing 12 of an oil Well or the like in any suitable manner, such as on a` tubing anchor of the type disclosed in the Charles H. Barnes United States Patent No. 2,603,294, issued July 15, 1952. The packer assembly 10 includes a packer head 16 which may form the upper portion of a tubing anchor, such as' disclosed in the aforementioned Barnes patent, an abutting segmental expansible packing member 18, a mandrel 20, and oil well flow tubing 14 on which the mandrel is supported. Packing 18 and packer head 16 are made of an inert material which is substantially rigid at temperatures and pressures encountered in the well, as will be described in more detail later in the speciiication. After the packer assembly 10 has been positioned in the Well, at a desired location, the mandrel 20 is then moved into engagement with the packing 18 to expand the packing into Vsealing engagement with the wall of casing 12. Removal of the packer assembly 10 from the Well is accomplished by rst relieving the pressureof mandrel 12 against the packing 18 to retract vthe same from engagement with the wall of the casing and thenremoving the packer assembly by removal of the tubing anchor or the like from thewell.

Packer head 16, which is of a diameter substantially sm'alle than the inside diameter of casing 12, is polished,

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lapped or smoothed,'so-tha`t its surface 22, which engages or abuts the packer 18, will provide a fluid-tight seal therewith. Further, packer head 16 has sucient clearance between it and the casing Wall so that it may be easily inserted into the casing 12. As shown in Figure l, packer head 16 is utilized when the well is provided with the flow tubing 14 and therefore must have a longitudinal bore throughout so that it may be received on the ow tubing. Since the packer head 16 may be supported on the flow tubing 14 by a tubing anchor of the type disclosed in the aforementioned Barnes patent, the bore through the packer head must be of such a diameter as to form a iiuid seal with the ow tubing 14 so that when packing 18 is expanded into sealing engagement with the wall of casing 12 to form a fluid seal therewith, the packer head also forms a fluid seal with the lower end surface of packing 18 and the outside of tlow tubing 14.

Packing 18 is comprised of a plurality of arcuate segments 24 held together as a cylindrical unit by means of one or more snap rings 26 which circumscribe the same. Segments 24 are made of an inert material which is substantially rigid at temperatures and pressures encountered in the well, such material being metals, metal alloys, or synthetic resins and the like. Snap rings 26 are received in grooves 28 on the outer surface of each of the segments 24 and, therefore, do not interfere with the sealing action of these surfaces against the wall of casing 12. As previously stated, snap rings 26 hold packing 18 in a retracted position, enabling the packer assembly to be inserted into the casing. When a fluid-tight seal is desired,

the packing 18 is expanded against the sides of the casing and snap rings 26 will consequently be expanded. When pressure is released from packing 18, snap rings 26 will return the segments to their abutting retracted position enabling the packer assembly 10 to be removed.

As previously mentioned, the packer assembly 10 including the mandrel 20, the packer head 16 and packing 18 can be made of any metal or metal alloy capable of withstanding a particular condition occurring at the point of use of the assembly in the Well. In other words, wells utilizing high caustc muds would require that the packer assembly be made of copper, copper alloys, stainless steel, titanium or the like. ln wells utilizing an oil base or asphalt drilling fluid, the packer assemblies could be made of metal or metal alloys such as aluminum, aluminum alloys, or the like. In all instances the metal or metal alloy used in the packer assembly must have a higher melting point than the temperature encountered in the well and must also be able to withstand the pressure encountered in the well. In modern-day drilling of wells, it has been found that temperatures up to approximately 400 F. and pressures up to 20,000 p. s. i. are encountered.

In place of metals or metal alloys the packer assembly can be made of synthetic resins which are inert under the conditions of the oil well and are substantially rigid at temperatures up to about 400 F. and preferably up to about 425 F. or 450 F.

An outstanding example of such a material is polytctrauc r. ethylene (Teon). The use of polytetrafluoroethylene has several advantages over metal or rubber packer assemblies. lt has been found that Teflon is ductile enough to make a good seal against the wall of the pipe. lt is not affected by any of the chemicals encountered in an oil well, and in this respect is superior to any known metal or rubber. It is very resistant to extrusion and will not vulcanize to the casing wall while being resistant to a considerable amount of heat. Although Teflon is not ductile enough to be utilized as a packing in a conventional sleeve form in the manner of rubber, unexpectedly it has been found ideally suited to be used in the packing of the segmented form of the packer assembly of the present invention.

While Teon is the preferred synthetic resin, otherA chemically inert, heat resistant and extrusion resistant resins `can be employed in some types of wells. Among ally overlapping surfaces.

such resins is polychlorotriuoroethylene (Kel-F). This resin possesses similar properties to those of Teflon, but not to the same degree. That is, Kel-F is less resistant to heat and chemicals and is not as resistant to extrusion although it is somewhat more ductile than Teflon. It is considerably lower in cost than Teon, and, hence, may be used as a substitute therefor wherever the condition of the oil well is not too drastic.

There can also be used other heat resistant synthetic resins such as asbestos filled polyethylenically unsaturated polyesters, e. g., asbestos filled polymerized diallyl phthalate.

Another synthetic resin which can be employed is an unfilled copolymer of ia polyalkyleneglycol bisallyl carbonate and an allyl substituted l, 3, 5 triazine, more especially a copolymer of diethylene glycol bisallyl carbonate with l0, 25 or 41.7% of tri'allyl cyanurate. Such a copolymer shows substantially no distortion 'at temperatures up to 410 F. and even higher. The copolymers are also Very strong. rThe 41.7% triallyl cyanurate copolymer is the best from the standpoint of resistance to heat distortion but it is also much more brittle than the copolymers with lesser amounts of this component.

in general, the metal, metal alloy, or synthetic resin should be one capable of withstanding pressures up to 15,000 p. s. i. and preferably capable of withstanding pressures up to 20,000 p. s. i.

Referring specifically to Figures 5 through 7 inclusive, segments 24, which form packing 18, Iare so arranged as to provide a fluid-tight surface to surface seal when expanded into engagement with the wall of casing 12. By having segments 24 in an overlapping relationship with each other, a fluid-tight seal will be provided when packing 18 is expanded into engagement with the wall of casing 12. To provide a fluid-tight seal, the segments must overlap each other in both a radial and a longitudinal direction. In other words, there must be longitudinally overlapping surfaces of adjacent segments 24 as well as radi- Each segment 24 is provided with a circumferentially extending projecting portion 30 which is of less radial thickness than the segment and also of less longitudinal length than the longitudinal length of the segment. Each segment 24 is also provided on its outer periphery 32 with a recess 34 of a size complementary to the size of circumferentially extending projecting portion 30. The recess portion 34 is adapted to receive the projection or overlapping portion 30 of an adjacent segment 24 and adapted to form a uid-tight seal between its radially extending surface 36 and the radially extending surface 36 of the overlapping portion 30. Also a fluidtight sealing surface will be provided between the longitudinally extending surface 3S of recess 34 and the longitudinally extending surface 38 of the overlapping portion 30 of an adjacent segment.

The normal process of manufacture, such as machining or molding of the segments, makes their sealing surfaces true enough for an adequate seal. However, to further insure a fluid-tight seal, the surfaces of each of the segments 24 of packing 18 may be polished, lapped or smoothed. By polishing the surfaces of segments 24, the surface to surface seal between adjacent segments is insured as well as the surface to surface seals between the packing 18 and the packer head 16 and the casing 12.

In order that packing 18 may be expanded into engagement and sealing position with the walls of casing 12, each segment is provided on its inner periphery with a tapered slightly concave surface 40. When packing 18 is in the retracted position, the tapered concave surface 40 on each of the segments 24 will form Ia tapered bore 42 therethrough. A-s previously explained, to expand packing 18, tapered mandrel 20 having a taper complementary to the taper of surface 40 and a bore 41 therethrough, is lowered with the flow tubing 14 and into contact with the tapered bore 42 after the packer assembly 10 has been temporarily anchored to the well casing. The wedging action of mandrel 20 against the tapered bore 42 will evenly expand the segments 24 into engagement with the walls of the casing 12.

As shown in Figure 2, the packer 18 has been expanded into sealing engagement with the walls of casing 12. It will be noted that the segments 24 of packing 18 overlap both radially as indicated at 36 and longitudinally, as shown in Figure 4, at 38".

Although the invention has been disclosed as forming a seal between the casing 12 of an oil well and a packer head 16, it is well within the scope of the invention that the packing structure may also be used to form a fluidtight seal in any portion of a string of pipe of :an oil well or in any conned enclosure such as 'a conduit or the like.

The operation of the device may be briefly summarized as follows:

If the packer assembly is to be utilized to form a seal between oil well flow tubing and a previous run casing, the packer head 16 is slidably supported on the section of well tubing 12 by means such as the tubing anchor shown in the `aforementioned Barnes patent. Packing 18 is supported in abutting relationship on the packer head 16 and the mandrel 20 which is attached or alixed to flow tubing 14 in any suitable manner is supported adjacent the packing 18 but not in expanding contact with the packing 18. The liow tubing 14 is lowered with the packer assembly 10 into the well casing and when the packer assembly has reached a desired position in the well casing, the packer head 16 is restrained from further downward movement in the casing by :any suitable means such as the tubing anchor of the 'aforementioned Barnes patent. The ow tubing 14 which has the mandrel 20 xe'd thereto is then lowered a short distance with respect to the packer head 1.6 and it engages the tapered bore 42 of packing 18 expanding the same outwardly into sealing engagement with the wall of casing 12. In other words, the relative movement toward each other of the packer head 16 and the mandrel wedges the segments 24 of packing 18 outwardly into sealing engagement with the wall of casing 12. Since the end surfaces 44, as well as the peripheral and overlapping surfaces of each of the segments 24 can form surface to surface seals, packing 18 will form a fluid-tight seal when the packer is expanded into engagement with well casing 12 or the like. The overlapping portions of segments 24 will insure that the packing 18 provides a seal not only radially but also longitudinally.

The advantages of having a packer assembly which is made of metal, metal alloys, or synthetic resins are obvious in present-day drilling of deep wells. High temperatures and high pressures are encountered or developed and the packer assembly of the present invention can be used with the high temperatures and pressures and yet will not deteriorate from such conditions. Further, the materials mentioned herein will not deteriorate under the use of high caustic muds or oil base or asphalt emulsion drilling fluids. By having the packing comprised of a plurality of radially movable, substantially rigid segments normally urged into abutting relationship with each other, the packing may be lowered into the well in its retracted position and then positively expanded into sealing engagement with the casing. Since the device is not affected by temperature, heat, or the chemicals in the drilling, the

packer assembly may be retracted Iand removed from the well when the necessity arises and, thus, may be used repeatedly.

The terminology used in this specication is for the purpose of description and not for limitation, as the scope of the invention is defined in the claims.

I claim:

l. In a packer assembly for use in a well casing or the like: said packer assembly including a cylindrically-shaped segmental expansible packing member, a packer head positioned at one end of said packing member and a tapered mandrel positioned at the other end of said packing member for expanding said packing member; said packing member having a retracted diameter substantially less than the diameter of the casing and compri-sing a plurality of outwardly movable arcuate segments 'having inner surfaces defining `a tapered bore, outer sealing surfaces having a radius of curvature when said packing member is expanded substantially equal to the radius of curvature of the inside surface of the casing and endwise sealing surfaces; each of said arcuate segments of said packing member being provided with a circumferentially extending portion of less thickness than the segment and of less longitudinal length than the longitudinal length of the segment, each of said arcuate segments also having a recess oppositely disposed from and of a size complementary to the size of said circumferentially extending portion, said recess in each of said segments receiving said circumferentially extending portion of an adjacent segment so that the segments overlap each other forming longitudinal and radial sealing surfaces; resilient means circumscribing said :arcuate segments for retaining them in position as a unit and normally urging them into a retracted abutting relationship with each other; said packer head having a circular cross-section with a maximum diameter substantially smaller than the diameter of the well leasing, said packer head also having an end sealing surface, said end sealing surface of said packer head abutting said endwise sealing surfaces of the segments of said packing member; and said tapered mandrel and said packer head being movable relative to each other to cause said mandrel to engage the tapered bore of said packing member and expand the segments of said packing member outwardly into engagement with the inner surface of the well casing to form a fluid seal between the packer head and the inner surface of the well casing.

2. A packer assembly of the character described in claim l including well flow tubing, and wherein said packer y head is provided with a longitudinal bore and is positioned on said llow tubing, said packing member also being positioned on said flow tubing land said mandrel being attached to said ow tubing for movement into the tapered bore of said packing member.

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