Well pack-off unit

Jan. 21, 1969

Filed Feb. 2J, 1956

C. W. BOUCHILLON

WELL PACK-OFF UNIT

3,422,902

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INVENTOR

CHARLES W. BOUCHILLON

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Attorneys

Jan. 21, 1969 c. w. bouchillon 3,422,902

WELL PACK-OFF UNIT

Filed Feb. 21, 1966 Sheet a of 2

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Attorneys

United States Patent Office

3,422,902

Patented Jan. 21, 1969

3,422,902

WELL PACK-OFF UNIT

Charles W. Bouchillon, Starkville, Miss., assignor to The Herschede Hall Clock Company, Starkville, Miss., a corporation of Ohio

Filed Feb. 21,1966, Ser. No. 528,713

U.S. CI. 166—202 21 Claims

Int. Cl. E21b 23/04; 33/12; F16j 15/14

ABSTRACT OF THE DISCLOSURE

A well pack-off unit having a plurality of seal components forming a seal system in which components in overlapping series form a seal with a well casing, each successively sealing component retaining fluid under pressure greater than that which a previously sealed component is capable of retaining.

This invention relates to well packers and more particularly to well packers for sealingly engaging a well casing when subjected to fluid pressure applied in a predetermined direction.

An object of this invention is to provide a well packer for sealing cooperative engaging with the casing of new as well as old wells in such a way as to minimize stressing of the casing in longitudinal directions and to minimize mechanical gripping of the casing by the packer.

Another object of this invention is to provide a well packer, which, while in sealing cooperation with a well casing, permits and accommodates changes in the relative length of the well casing and the length of a pipe string secured to the packer and also secured in fixed relation to the well casing at a location remote from the packer as, for example, at the well head, the accommodation being by movement of the packer longitudinally of the bore of the well casing.

Another object of this invention is to provide a well packer of a simple construction, adapted for manufacture at low cost and which may be easily serviced in the field to provide a unit of long reliable service life.

Another object of this invention is to provide a device of the above character, use of which tends to minimize thermal elongation of a well casing and to minimize direct mechanical transfer from the packer to the well casing of upwardly directed force hydrostatically applied to the packer from below.

Another object of this invention is to provide a well packer which is easily insertable into the head end of a well casing.

A further object of this invention is to provide a device of the above character which is easily advanceable downwardly within a well casing to a predetermined level as desired.

A further object of this invention is to provide a device of the above character which is recoverable from a well casing without damaging the casing.

A further object of this invention is to provide a device of the above character which cooperates with a well casing to preclude fluid under any pressure within an extended range passing between said packer and said well casing in a predetermined direction in said well casing.

A further object of this invention is to provide a device of the above character which cooperates with a well casing to preclude fluid at temperatures within an extended range and under any pressure within an extended range passing between said packer and said well casing in a predetermined direction in said well casing.

A further object of this invention is to provide a device of the above character which cooperates with a well casing to preclude fluid passing between said packer and said casing as the pressure increases on the fluid under isothermal conditions and also under rising temperature isobaric as well as increasing pressure.

g A further object of this invention is to provide a device of the above character which remains in fluid sealing cooperation with a well casing.

A further object of this invention is to provide a device of the above character including cooperating seal10 “ig elements which are progressively actuatable in overlapping succession in response to rise in temperature and to rise in pressure to attain sealing at elevated temperature and pressure conditions above those which the first sealing element can withstand.

A further object of this invention is to provide a device of the above character comprising a body having a shoulder slightly smaller in diameter than the diameter of a well casing bore and a cup ring form seal system mounted in annularly encircling sealing relation to said body, said seal system comprising a plurality of deformable cups nestingly stacked in sealing relation to one another with their bottoms toward the shoulder and their mouths facing axially away therefrom, the cup adjacent the shoulder having its bottom in sealing contact with the shoulder and being the cup most resistant to elevated pressure and temperature each cup successively remote from the shoulder being less resistant to elevated temperature and pressure and having its rim extending further from said shoulder, the first cup most remote from the shoulder sealingly engaging a well casing and being expandable by fluid pressure acting on its inward face to form the sealing area adjacent the rim of the first cup toward the shoulder progressively expand the seal system to engage an increasing area of the casing with increasing tightness, the first cup expanding to engage an increasing area of the casing and then expanding the adjacent second cup to place an increasing area thereof in sealing engagement with the well casing before the first cup is subjected to environmental conditions under which it begins deteriorating, successive cups being similarly activated in overlapping sequence to provide a fluid tight seal effective under changing environmental conditions as imposed by the fluid sealed.

A further object of this invention is to provide a device of the above character comprising a body having a shoulder slightly smaller in diameter than the diameter of a well casing and a cup ring form seal system mounted in annularly encircling sealing relation to said body, said seal system comprising a soft metal cup, a poly-tetrafluoroethylene cup, and an elastomeric cup nestingly stacked in sequence therein with the bottom of the soft metal cup resting against said shoulder, the rim of the elastomeric cup projecting away from the shoulder and axially from the metal cup and radially outwardly to sealingly engage a well casing, the elastomeric cup being advanceable in longitudinal sealing relation within a well casing, whereby an annular band-like area of the external surface of the elastomeric cup is sealingly engageable with a well casing and as the cup is subjected to increasingly higher pressure the width of band-like area of sealing engagement progressively expands and the poly-tetrafluoroethylene cup is expanded into similar progressively expanding sealing engagement with the well casing before the elastomeric cup begins to deteriorate under environmental conditions and as the pressure on the sealed fluid increases further the poly-tetrafluoroethylene cup continues to expand and progressively expands the soft metal cup into sealing engagement with the well casing before the poly-tetrafluoroethylene cup is subjected to conditions under which it might tend to extrude past the soft metal cup, and the soft metal cup under further elevated pres20

3,422,902 sure is expanded to lie in supported relation to said shoulder and sealingly bridge the gap between the shoulder and the well casing.

The above and other features and objects of the invention will in part be obvious and in part be apparent to those having ordinary skill in the art to which this invention .pertains, from the following detailed description and the accompanying drawing of what presently appears to be a preferred embodiment of the instant invention.

In the drawings:

FIG. 1 is a view in section of a portion of a well casing w'ith a steam injection line extending downwardly into the well casing and equipped with two packers embodying the instant invention;

FIG. 2 is a fragmental view, partly broken away, showing details of construction of a portion of a well casing together with a well packer embodying the instant invention disposed therein, the well casing being shown in section and the well packer being shown in full to the left of the center line and in cross section to the right of the center line, the packer being in cooperation with the well casing in a manner characteristic of such well packers in the absence of sufficient pressure on the fluid sealed as would tend to further actuate the seal system forming part of the packer;

FIG. 3 is a fragmentary view in section and on an enlarged scale showing the seal system and adjacent elements of the device of FIG. 2 in a relation they assume while sealing fluid under elevated pressure;

FIG. 4 is a fragmentary view in section showing the seal system and the adjacent elements of the device of FIG. 2 in the relation they assume when pressure on the fluid sealed is increased to higher values than those which produce the relationship of FIG. 3;

FIG. 5 is a fragmentary view in section showing the seal system and adjacent elements in the relationship assumed when the fluid sealed is under a pressure greater than that which produces the relationship of FIG. 4;

FIG. 6 is a fragmentary view in section of the seal system in association with adjacent elements and showing the relationship assumed by the seal system in sealing fluid under higher pressure than that which places the seal system in the relationship of FIG. 5; and

FIG. 7 is a fragmentary view in section of the seal system in association with adjacent elements and showing the relationship of the seal system to the well casing as withdrawal of the steam line has progressed to the point where the packer is near the well-head.

In the drawings and the following description, like reference characters indicate like parts.

While well packers may be used in connection with various well operating and service activities, the device of the illustrative embodiment is a well packer which may be used for example, in connection with cleaning as well as in treating of oil wells or sub-surface formations from which substances may be withdrawn through such a well. One use for which packers constructed in accordance with the illustrative embodiment may be used is steaming of the bottom portion of the well, for example, the strainer and surrounding area and also the strata such as an oil bearing formation from which it is desired to recover oil through the well. Steaming is performed on older wells to heat the oil bearing formation to increase the rate of recovery of oil from the formation through the well or to recover oil not recovered or recoverable through natural flow. Steaming is also performed on wells through which high paraffin content crudes are recovered as such crudes often result in accumulation of paraffin in the strainer and adjacent formations with a resultant choking of the flow of oil into the well casing.

Steaming of a well involves injection of steam down the well into the oil bearing formation. Such injection is at times effected through a line smaller in diameter than the inside diameter of the well casing and extending sub4 stantially to the foot of the well casing, sometimes called open bottom steaming. Use of a steam line alone involves substantial waste of steam, i.e., heat, due to escape of steam through the casing back toward the head of the casing annularly of the steam injection pipe. Such open bottom steaming in a well cased to a depth of approximately 1,500 feet not infrequently will result in linear thermal expansion of the well casing so that a well head normally at about ground level will rise to a height of the order of 5 feet above ground level. The joints in well casing are customarily threaded taper joints which by their nature are adapted to withstand compressive forces of much greater magnitude than that of tension forces under which they tend to fail. These threaded ₁₅ taper joints are loaded in compression by the weight of the casing and during elongation of the well casing due to thermal expansion during open bottom steaming remain so. At times upon conclusion of the injection of steam, some cold water is injected down the steam line be2o hind the steam producing rapid chilling of the lower portion of the well casing accompanied by thermal shrinkage which not infrequently results in the application of tension forces sufficient to induce failure of the threaded taper joints of the casing.

Various packer or pack-off units, as they are sometimes called, have been used in the past to effect a seal between a steam injection line and a well casing at or near the bottom end of the latter. Such packers customarily incorporate mechanical means for fixedly anchoring the 30 packer to the portion of the well casing in which the packer is positioned.

As shown in FIG. 2, a well packer embodying the instant invention in what presently appears to be a preferred form, has a body 16 of generally cylindrical form having 35 a tapered pipe thread 17 adjacent its upper end 18 and a similar tapered pipe thread 19 adjacent its lower end 20. Intermediate the ends 18 and 20 body 16 has an annular shoulder 21. Shoulder 21 has a cylindrical peripheral surface portion 22 of slightly smaller diameter than 40 the internal diameter of well casing 23 and is thus in close spaced relation to the inner surface 24 of well casing 23. The peripheral surface portion 22 of shoulder 21 is part of the exposed continuous external surface of body 16, which surface successively includes the external cylin_4f. drical surface 25 adjacent thread 17, the concave outwardly flaring portion 26, the convexly curving surface portion 27, portion 22, and a convexly curved surface portion 28. The external surface of body 16 engaged by the seal system as shown in FIG. 2 is a further continua₅₀ tion of the surface including portions 25, 26, 27, 22, 28, and successively includes concavely curved shoulder surface portion 29 which merges into cylindrical surface portion 30 which extends from shoulder 21 to threads 19.

The tapered pipe threads 17 and 19 provided on the ₅₅ opposite ends of body 16 are of a standard thread size and pattern customarily provided on a conventional like size casing pipe, which, for purposes of illustration might be commercially denominated 3 inch pipe, in connection with which the packer is intended to be used where the βθ casing 23 might be of a size commercially referred to as 5½ inch casing.

The surface areas 28, 29 and 30 of the body 16 are carefully machined and smoothly finished to receive a seal system in fluid-tight sealing annular cooperating re05 lation thereto.

The seal system 39 shown in the drawings comprises a first component 40, an annular ring form cup 40 of soft aluminum or the like; a second component 60, an annular ring form cup 60 of polytetrafluoroethylene, and a third 70 component, an annular steel ring 80 to which is secured an annular ring form cup 100 composed of an elastomer such as rubber or rubber-like material. The seal system composed of elements 40, 60, 80 and 100 are secured in relation to body 16, shown in FIG. 2, by seal pressurizing 75 collar 120 and coupling 115.

3,422,902

Coupling 115 has adjacent its end 117 an inwardly extending cylindrical face 116 and adjacent face 116 are provided the tapered pipe threads 119 which cooperatively engage the tapered pipe threads 19 of body 16. Coupling collar 115 adjacent end 117 thereof has external straight threads 118 with which internal threads 123 provided on seal pressurizing collar 120 cooperate. Seal pressurizing collar 120 has an annular external shoulder 121, the peripheral edge of which is a cylindrical peripheral surface 122 of substantially the same diameter as the cylindrical surface portion 22 of shoulder 21 on body 16, and like surface portion 22 is a connecting continuation of convexly inwardly curving surface portions 127 and 128.

Coupling 115 also connects a length of steam line or pipe 130 to body 16, having standard casing pipe tapered threads 131 with which coupling threads 114 cooperate.

The seal system may be fabricated in the form of component parts. The first component 40 may be fabricated from a soft aluminum which, for example, may be an aluminum alloy such as 2S or 6061T6 annealed to soften after it is machined or formed to a ring cup shape of cross section similar to that shown in FIG. 2. The second component of the seal system, ring form cup 60, may be made by die molding polytetrafluoroethylene to form a ring form cup having a cross section conforming substantially to that indicated in FIG. 2. The third component, a steel ring 80 of a cross sectional configuration conforming to that indicated in FIG. 2, is machined so that it has an internal cylindrical surface 81 which will closely conform to the cylindrical surface 30 of body 16. The internal cylindrical surface 81 of the ring is contiguous to a convex annular nose surface 82 which extends from the corner line of intersection 83 to the edge 84. From the second edge 85 of surface 81, a radial surface 86 extends outwardly to an edge 87. The surface of ring 80 between edge 87 and edge 84 extends cylindrically to a generally radially and outwardly projecting rib 88 and then from rib 88 cylindrically and concavely outwardly flaring to edge 84, as shown in FIG. 2. The surface 89 of ring 80 from edge 84 to edge 87 which includes the surface of rib 88 is preferably a roughened or a roughly finished surface.

Ring 80 is provided with a rubber cup ring form skirt 100 which may be made separately and then attached to ring 80 or die molded to directly bond it to that ring. The ring form skirt 100 has a somewhat bell-shaped inner surface 101 extending from the edge 87 of ring 80 to a rounded edge 102. The surface of member 100 continues from inner surface 101 around edge 102, and then, in the surface area 103, simultaneously outwardly toward casing surface 24 and upwardly toward the location of the ring 80 to a cylindrical annular surface area 105 which extends from corner 104 to corner 106 of the cup and lies in engagement with casing surface 24. The corners 104 and 106 may be slightly rounded. From corner 106 the outer surface areas 108 and 109 of cup 100 successively converge inwardly and upwardly toward ring 80, the inward convergence being more pronounced in the area 108 which extends from corner 106 to a line of deflection 107 (FIG. 2) and from which line 107, area 109 extends in a converging convex fashion to edge 84 of ring 80.

The cup 100 may be reinforced by incorporating in the cup adjacent ring 80 a ring or cord 90 extending annularly in cup 100 in close space relation to ring 80 and adjacent rib 88 at a location such as shown in FIG. 2, to resist expansion of cup 100' and thus in anchoring of cup 100 to ring 80. Cords, fibers or fabric 112, such as nylon, poly-ester, mineral fibers or the like as are useful in reinforcing elastomers, cooperate with ring 90 and extend therefrom toward edge 102 of the cup to reinforce the cup and provide greater resistance to rupture under tensioning of the member 100 particularly in a direction parallel to the axis of the well casing. The reinforcement 112 is preferably either in the form of threads or filaments ⁶ extending as indicated in FIG. 2 or in the form of a fabric which is cut on the bias or is elastic in a direction as will permit outward bulging, increase in girth, of the member 100 between ring 80 and the casing engaging section of its surface 105. The member 100 is bonded and securely attached to the surface 89 of ring 80.

Elements 40, 60 and the assembly of ring 80 and cup 100 are assembled in the nested relation in the sequence shown in FIG. 2 to form a seal system which is then mounted on the body 16. The seal system, in annular collar fashion, is advanced from end 20 onto body 16 with elements 40 and 60 in snug sealing press-fit relation to cylindrical external body surface portion 30 and ring 80 fitting surface 30 closely, until element 40 abuts surface area 29 of shoulder 21.

Coupling 115 is advanced into seal pressurizing collar 120 to place threads 118 in cooperating relation with threads 123 and then rotated to advance coupling 115 to the limit position, as far toward end surface 124 as possible. Threads 131 of pipe 130 are placed in cooperating relation to thread 114 of coupling 115 and threads 119 of coupling 115 are then placed in cooperating relation with body threads 19. Means such as a pipe wrench may be engaged with cylindrical body surface area 25 and similar means engaged with pipe 130 and manipulated to rotate pipe 130 relative to body 16 in the direction necessary to fully tighten the threaded joints between coupling 115 and the body 16 and between coupling 115 and pipe 130 to steam tight relation. Seal pressurizing collar 120 is then rotated to advance it toward shoulder 21, moving its radial end face 124 into abutment with radial end face 86 of ring 80 and then advancing ring 80 toward shoulder face 29 to clamp cups 40 and 60 between shoulder face 29 and face 82 of ring 80. The faces 82 and 29 are not evenly spaced as from adjacent body surface area 30 they approach each other, that is their spacing along a line parallel to surface area 30, as the latter is shown in FIG. 2, decreases until the line 92, extending parallel to body surface 30 and through the tip of the “nose” 93 of ring 80, is reached, and, from that radial distance outwardly of the surface 30, surface 82 diverges from the opposed surface 29 of shoulder 21. Advanced ring 80’s compressing action upon cups 40 and 60 places the surface areas of cup 60 adjacent the wedge toe edge 61 thereof in particularly effective sealing relation with body surface 30 and the adjacent portion of ring surface 82. Also the compressing action of ring 80 produces similar sealing cooperation between the surfaces of cup 40 contiguous to the wedge toe edge 41 and the opposed surfaces, body surface 30 and cup surface 62. Thus, cups 60 and 40 are placed in steam tight sealing relation to body surface area 30.

It may be noted that in the device shown in FIG. 2 the seal pressurizing collar has a downwardly extending annular skirt 125 which may be engaged by a pipe wrench or the like for convenience in rotating seal pressurizing collar 120 relative to body 16 incident to effecting the above described clamping of cups 40 and 60 in steam tight sealing relation to body 16.

In making the seal system components and assembling them with each other prior to placing the assembly in annular cooperating relation with body 16, they may be fabricated to have an external cylindrical surface from 42 to 62 in FIG. 2, of a diameter greater than that indicated in FIG. 2 and the external diameter of cup portions 40 and 60 may be reduced to that shown in FIG. 2 either by machining prior to assemblage of the seal system with the body 16 or such machining may be accomplished after the seal system has been mounted in cooperating relation on body 16 as described hereinabove.

As shown in FIG. 2 the external diameter of cups 40 and 60 is preferably slightly smaller than the external diameter of shoulders 21 and 121, that is the cylindrical surface 22 if projected would coincide with cylindrical surface 122 and the cylindrical surface of elements 40

3,422,902 and 60 from 42 to 62 would lie within the above mentioned cylindrical surface so that shoulders 21 and 121 afford mechanical protection to the external surface of elements 40 and 60 between 42 and 62.

When the packer of FIG. 2 is not disposed within a well casing, the elastomeric cup 100¹ resiliency expands outwardly and the diameter of the cylindrical surface area 105 thereof is greater than that shown in FIG. 2.

In FIG. 1 a segment of well casing consisting of one length of casing pipe 140 joined by coupling 141 to the lower end of a superadjacent casing pipe 142 and by coupling 143 to a subjacent length of casing pipe 144. A portion of an element of steam line 146 has secured to its lower end by coupling 149, a well packer 15, such as is shown in FIG. 2, a second packer 15' is joined to packer 15 by an intervening length of steam pipe line 133 and coupling 148. An additional length of steam line pipe 147 may be attached to and extend below packer 15'.

Insertion of the steam line into a well casing is accomplished from the upper or well head end of the casing. The section of pipe 147 is placed in and held by the pipe holding device mounted at the well head and sometimes called a slip. Packer 15' is then threadedly engaged on the upper end of pipe 147, which engagement can be accomplished in a manner similar to that in which pipe 130 in FIG. 2 is attached to the packer there shown. A length of pipe 133 is then raised and its lower end is coupled to the upper end of packer 15' by means of a conventional coupling 148. It will be noted that pipe 133 is substantially shorter than the length of the conventional section 140 of the well casing. The joints in the assembly of pipe 147, packer 15', coupling 148 and pipe 133 may be tightened in any usual manner as by means of a pipe wrench or the like engaging pipe 133 and appropriately rotating same until the threaded joints between pipe 147 and packer 15' 35 and between packer 15' and coupling 148 and between coupling 148 and pipe 133 are drawn up into steam tight relation. The assemblage of elements 147, 15', 148 and 133 are then released from the slip and lowered down10 ⁸ coupled together by sleeve coupling 31. The inner face 35 of coupling 31 is exposed in concentric relation to the surfaces 241 and 24, but is located outwardly of those aligned cylindrical surfaces. Thus, as the well packer adjacent the lower end of the steam pipe is lowered into the well casing, it will first have the cylindrical external surface 105 of the elastomeric cup 100 in sealing engagement with surface 241 of the casing pipe section 231, but as it is advanced downwardly, the surface 105 will slide along surface 241 and beyond edge 36 toward the upper end of pipe 23. As the surface 105 progressively advances downward beyond edge 36, the cup 100 tends to expand into the area defined by faces 341, 35 and 34. However, the configuration of the cup 100 downwardly from cylindrical surface area 105 is such that the cup is guided into the bore of casing pipe 23 and cylindrical surface 105 then slides into sealing engagement with inner surface 24 of the lower pipe. It may be noted that the vertical extent of surface 105 is slightly greater than the distance X, the width of the spacing between the adjacent lengths of well casing, so that cooperation of the surface 105 with surface 24 commences before its cooperation with surface 241 is completely terminated in the case of a joint of dimensions such as illustrated in the upper portion of FIG. 2. It should be understood that at times such joints are of different dimensions and the configuration of the external surface of cup 100 between its lowermost portion 102 and external surface portion 105 is such that it will serve to pilot the cup 100 into the lower casing as the well packer is advanced downwardly in the well past collar joints having a wider annular recess.

Incident to lowering of the packer into the well, the cup 100 by reason of its being held to a smaller diameter in the well casing than it would normally assume when the packer is located in the free air, has the cylindrical outer surface area 105 in substantial sealing engagement with the inner face of the casing pipe within which it is located. The inner surface of such pipes may have various _______________________________________x kinds of foreign matter, such as sand, bits of rock or the wardly into the well casing. The elastomeric cup 100 like, adhering to them, and they may also be roughened being contracted or compressed so that it may be ad- ..---. ...- .. .- .......

vanced into the well casing wherein it may expand until its cylindrical external surface area 105 sealingly engages the internal wall face of the well casing. The mentioned assemblage is then lowered to the position in which pipe 133 may be gripped by the slip and held with its upper end positioned and packer 15 similarly attached thereto. It should be noted that both packer 15 and packer 15' are positioned with the respective shoulder 121 of the seal pressurizing collar 120 of each disposed below, that body 16 to be cocked in the casing will result in contactis, further down into the well than the shoulder 21 of the body. The additional lengths of steam pipe with couplings are successively added to the upper end of the string and the assemblage lowered into the well until the packer 15' is at the desired depth in the well.

As is shown generally in FIG. 1, a well casing is composed of a series of lengths of pipe which are coupled by sleeve couplings to form a continuous tubular casing assembly of sufficient length to reach downwardly to the by corrosion due to their exposure to substances in or moving through the interior of the casing during operation of the well. For this reason, the elastomeric material from which cup 100 is fabricated is preferably material having exceptionally high resistance to abrasion damage as well as being resistant to hydrocarbons.

It should also be noted that cups 40 and 60 are protected from abrasion by the well casing and foreign matter by reason of the fact that any tendency of the packer ing of shoulder 21 or shoulder 121, or both, but not cup 40 or 60, with the casing because the shoulders 21 and 121 are located on opposite sides of the seal system 39 and extend radially outward further than cups 40 and 60.

The packer is preferably lowered into a position in the well casing such that it will remain within a single length of the well casing, that is, between two joints such as that illustrated in the upper portion of FIG. 2, and which _________ ________________ ________________ _ would correspond to the joints encircled by couplings 141 depth necessitated by the particular well. The joints which ₆₀ and 143 in FIG. 1. It may be remembered that the steam occur at the location of each coupling are illustrated by the joint shown in greater detail in the upper portion of FIG. 2 where a coupling 31 is shown having tapered internal threads 32 cooperating with the tapered external injection line hangs in the well and may be anchored to or adjacent the well head, that is, the upper end of the well casing, and, as a result, the packer does not remain stationary in relation to the particular portion of well threads ^Fat the upperend of casing section 23 and 65 “sing disposed immediately annularly of it. On the condrawn up to form a fluid-tight joint. A fragmentary por- ’ n-x...tion shown of the superadjacent length of casing pipe 231 has tapered external threads 331 adjacent its lower end in cooperation with threads 321 forming a fluid-tight trary, movement of the packer relative to a particular portion of the well casing is the result of a number of factors which come into play incident to steaming of a well.

_______ ___________________________ In the event that the packer most nearly adjacent the seal joint between casing pipe 231 and coupling collar 31. 70 lower end of the steam line exemplified by packer J5' in The inner face 241 of casing pipe 231 is thus aligned with «=-·—inner surface 24 of pipe 23, tout is spaced therefrom a short distance X, the distance by which the radial upper end face 34 of pipe 23 is spaced from the lower radial

FIG. 1 moves relative to the casing a distance sufficient that it tends to pass or does pass a joint in the casing, damage to or failure of the packer seal may result, but __________ __ in such case the packer located at a higher point in the end face 341 of pipe section 231 when the two pipes are 75 steam line, such as packer 15, will normally be in a loca3,422.902 ⁹ tion where there is no casing joint and can effect a seal with the casing.

Under normal operations where the packer such as 15' does not pass a joint in the well casing while the steaming operation with its elevated temperatures and pressures is in progress, the packer 15 normally remains an inoperative auxiliary sealing device insofar as substantial sealing action incident to steaming is involved.

Further remarks in reference to the factors tending to influence or cause longitudinal movement of the packer relative to the well casing in a longitudinal direction during operation of the packer incident to steaming will be deferred and the setting of the seal system of the packer in cooperating relation to the well casing to seal the well casing and retain fluid under elevated temperatures and pressures in the casing below the packer described.

When the packer has been lowered to the desired depth in the well casing preparatory to commencement of steaming, the packer will be substantially in the condition illustrated in FIG. 2 with the cylindrical external surface 105 of cup 100 pressed outwardly and in sealing engagement with surface 24 of the casing under the forces inherent in the cup 100 tending to expand same to its free condition. The upper end of the steam line is connected to a steam generating device, such as a boiler, and steam is injected downwardly through the steam line and through the axial bore in body 16 of the packer and into the well casing at a level below that at which cylindrical surface 105 of rubber cup 100 sealingly engages the wall 24 of the well casing. Steam introduced may condense on various surfaces present such as the inner face of the well casing below the packer and other portions of the well equipment as well as the geological formations accessible to it. It may also pass into cavities in the geologic formations. However, as steam is continuously injected, the temperature of the steam line, the packer elements, the casing and other well equipment below the packer, as well as the geologic formations in the vicinity, are progressively heated and the hydrostatic pressure in the steam line and in the casing below the seal system of the packer and in areas in communication therewith rises as well. The increase in hydrostatic pressure results in application of increasing force to area 101 of rubber cup 100 tending to expand the cup and to push it toward the wellhead. Also, since in steaming such increase in pressure is also accompanied by an increase in temperature, the physical properties of the material, whether rubber or other selected elastomer, in cup 100 change as well. The result is that as pressure and temperature continue to rise, the cup 100 is bulged outwardly and surface areas 108 and 109 thereof are progressively, from adjacent area 105, advanced toward surface 24 of the well casing annularly thereof. The external surface of cup 100 above area 105 thereof and below the lower extremity of cup 60 in thus progressively moved into contact with well casing surface 24.

As previously explained, cup 60 in the illustrative embodiment is polytetrafluoroethylene, and this material under the increasing pressure and increasing temperature conditions tends to become increasingly deformable and begins to expand outwardly when temperature and pressure conditions increase to suitable levels. The lip of cup 60 lying against the exterior of cup 100 gradually expands and moves toward and into contact with casing surface 24 and the condition illustrated in FIG. 3 is reached. The condition of FIG. 3 is reached before environmental circumstances are reached under which any significant degeneration of the elastomeric material of cup 100 occurs. The elastomeric material may be any one of those presently available rubber-like materials which have satisfactory physical properties to function as a seal element at temperatures of the order of 300° F., and possibly more, and withstand the hydrostatic pressures of upwards of 50 p.s.i. (pound per square inch gauge) which accompany steam of such temperatures as well as having high abra10 sion resistance, hydrocarbon resistance and steam resistance.

As the steaming continues, the rise in pressure and temperature is also continued, and the hydrostatic pressure deformation of the seal system progresses with further expansion of cup 100 continuing and accompanied by further expansion of cup 60 so that the external surface thereof moves into sealing engagement with casing surface 24 in an annular area of width increasing from the 10 thin lip edge 62 progressively toward shoulder 21 to such degree that cup 60 is in effective sealing engagement with casing surface 24 when the material of cup 100 commences to deteriorate to a degree that, in the absence of cup 60, failure of the seal would result. Deterioration of 15 the elastomeric material may occur in various ways and may involve carbonization, fissurization and the like. Upon failure of the cup 100 as a seal, ring 80 being in engagement with the polytetrafluoroethylene cup 60 maintains the seal between cups 60 and 40 and body 16. FIG. 20 4 illustrates the condition which the seal system may reach at about the time cup 100 has degenerated to the condition in which it would become unsuited for maintaining a seal, and it may be noted that the thin edge-like lip 43 of aluminum cup 40 has commenced to expand 25 along with the adjacent portions of the wall of cup 40, thus supporting cup 60 which is functioning as the seal between the packer and the well casing in the condition of FIG. 4.

As steaming progresses and the temperature and pres30 sure continue to rise, the seal system is expanded gradually from the condition of FIG. 4 to the condition of FIG. 5 in which a substantial portion of the external surface 44 of cup 40 as well as the exposed external surface 64 of cup 60 lie in sealing relationship with surface 24 35 of the well casing. Also, cup 60 may move away from cup 100 and a portion of ring surface 82 leaving voids such as 50 which can fill with steam. A condition such as that exemplified by FIG. 5, in which cup 40 is in sealing relation to well casing surface 24, is established be40 fore the polytetrafluoroethylene cup 60 is subjected to conditions of temperature and pressure under which the polytetrafluoroethylene material will extrude. From the condition of FIG. 5, the increase in temperature and pressure may continue further with the result that cup 40 45 is expanded and formed such that its surface 45 moves into supported relation with surface area 28 of shoulder 21 to a degree such as is exemplified by the showing of FIG. 6. Cup 40 thus bridges only a small gap between the surface 24 of the well casing and the adjacent por50 tion of the surface 28 of shoulder 21 against which the cup 40 is supported under conditions of elevated temperature and pressure.

_ Thus, the elastomeric cup 100 will withstand the action of insertion of the packer into the well casing to the 55 location desired and there maintain both initial and continuing sealing engagement with the surface 24 of the well casing until the polytetrafluoroethylene cup 60 has been expanded to sealingly cooperate with the surface 24. It may be noted that polytetrafluoroethylene and soft 60 aluminum have much lower abrasion resistance than the elastomeric materials available for formation of cup 100. Further, the external exposed area 64 of the polytetrafluoroethylene cup 60 continues and increases sealing cooperation with surface 24 under conditions under which 65 the material of cup 100 fails and that aluminum cup 40 expands into sealing cooperation with surface 24 before polytetrafluoroethylene cup 60 is subject to environmental conditions under which cup 60 would fail by reason of extrusion between cup 40 and surface 24 or the like. 70 Also, the aluminum cup 40 under further increased pressure and temperature expands further into the fully expanded condition of FIG. 6 in which it is in further sealing engagement with surface 24. The packer of applicant is thus a pressure actuatable seal system which 75 may be inserted into a well casing and in response to

3,422,902 mounted on the stem in adjacent relation, a first of said members being of rubber-like material forming an initial seal against a casing and expandable outwardly under pressure to engage and seal more tightly against said casing, a second of said members being of yieldable plastic material less readily yieldable than the first member, there being a third said cup-shaped member of yieldable metal, the first member engaging the second member on application of increased pressure against the first member to force the second member against the casing to form a seal therewith, the second member engaging the third member on application of further increased pressure to force the third member against the casing to form a seal therewith.

4. A combination as in claim 3 in which the second member is polytetrafluoroethylene and the third member is aluminum.

5. A combination as in claim 3 in which there is a rigid shoulder on the stem engageable by the third member to limit deformation thereof.

6. A combination as in claim 3 in which there is a rigid rib on the. stem adjacent but spaced from the first member and extendable in closely spaced relation with the casing to engage and catch portions of the members which become detached from the stem incident to removal of the packer lengthwise of the casing.

7. A combination as in claim 3 in which there is a rigid shoulder on the stem supportingly cooperating with the third member and extending in closely spaced relation to the casing, the second member being disposed intermediate the first and third members and spaced from said shoulder, the first member having a central metal ring portion engaging said stem and an outer cup portion annularly thereof, and means advanceable along said stem toward said shoulder to clamp said ring portion of said first member and the second and third members in relation to each other the shoulder and stem to continuously form a seal with said stem both when the outer cup portion of the first member extends in sealing spanning relation to the central metal ring portion thereof and the casing annularly spaced from said ring and when the outer cup portion of the first member does not extend in sealing spanning relation to the central metal ring and the casing.

8. In a well packer for sealing cooperation within a well casing the combination comprising a body, a seal system secured in annular sealing relation to said body, said seal system having a plurality of components actuatable to sealingly cooperate with an annular well casing in overlapping series, a first said component for resiliently establishing an initial seal with a said well casing and when subjected to sufficient fluid pressure placing a second component in sealing cooperation with a said well casing to retain fluid under pressure in excess of that which said first component is capable of retaining.

9. A device in accordance with claim 8 characterized by the fact that a first cup-shape ring component of said seal system resiliently cooperates with an annular well casing to form an initial seal therewith and is oriented so actuating fluid pressure may act against the inward surface of the cup-shaped ring to expand the cup into sealing relation to the casing of a tightness related to the magnitude of the fluid pressure, sealed.

10. A device in accordance with claim 8 characterized by the fact that the first cup-shape ring component of the seal system is nested in a second cup-shape ring component and said second component sealingly engages said first component and said body.

11. A device according to claim 8 characterized by the fact that said body has an annular shoulder, that said seal system comprises a plurality of ring-form cups annularly of said body and stacked in nested relation with their rims remote from said shoulder and each cup having a portion of another nested therein being of material less yieldable than the material of the cup nested therein, that a compression ring secures said seal system in annular sealing rela- application of hydrostatic pressure effect a seal to withstand conditions of temperature and pressure which the elastomeric or the polytetrafluoroethylene cups alone or in combination could not withstand but which cups make possible application of a sufficiently high hydrostatic pres- § sure to form and set a metal seal cup which though so formable is also strong enough to withstand the temperatures and pressures applied as it sealingly bridges the gap between shoulder 21 and the casing face 24. Upon conclusion of steaming the pressure falls and the packer ₁₀which may have been exposed to temperatures in excess of 600° F. and to pressures in excess of 1500 p.s.i. for hours or days may be withdrawn up the well casing as the steam line is pulled and disassembled. Such withdrawal results in the outwardly displaced portions of cups ₁₅40 and 60 and member 100 being abraded and reduced toward or to a diameter corresponding to that of the shoulders 21 and 121. In view of the probable temperatures and pressures reached in steaming elastomeric cup 100 may carbonize or become brittle and develop fissures 111 20 and although reinforcement 112 is provided, same may not prevent crumbling or breaking off of parts 110 of cup 100. Those of substantial size would be caught and carried upward on top of shoulder 121. Also, cup 60 may develop cracks 66 as its surface 64 is pulled loose from 25 casing face 24 and should any substantial part separate completely from the cup, shoulder 121 would tend to carry it upward toward the wellhead as well. However, the physical properties of the components of the seal system 39 are such as will not result in substantial dam- 30 age to the well casing incident to withdrawal of the packer when steaming has been concluded.

The used seal system can be removed and a new one provided on body 16, restoring the packer to condition for use. 35

The forces acting on the packer and tending to move it relative to the well casing during steaming generally arise from several factors.

As steaming is commenced the steam line is heated and undergoes thermal expansion. Since the steam line is 40 anchored at the wellhead, elongation tends to lower the packer further down in the casing. Heat transfer from the steam line to the casing above the packer is slow and thermal elongation of the casing above the packer thus is not great, but such as occurs tends to cause the casing to “grow” up out of the well (wellhead rises) and so tends to offset in part the tendency of the packer to lower as the steam line expands. Also, hydrostatic pressure under the packer tends to push the packer towards the wellhead.