A subterranean well tool such as a packer and attached telescoping seal receptacle assembly is disclosed. The tool is fabricated from a plurality of threaded tubular members and annular deformable rings fabricated of a metal softer than the tubular members are used to establish metal-to-metal sealing integrity between interengagable component members. Upon full engagement, sealing integrity is established along the transverse interface between each tubular member and the deformed seal ring. During initial disengagement, sealing integrity is maintained along a bearing inclined interface between the ring and at least one tubular member adjacent the threaded connection.

BACKGROUND OF THE INVENTION 
1. FIELD OF THE INVENTION 
This invention relates a threaded connection especially for use in a tool 
insertable within a subterranean well, metal-to-metal sealing integrity 
being maintained between threaded components of the tool itself. 
2. DESCRIPTION OF THE PRIOR ART 
In subterranean oil and gas well applications it is often necessary to 
establish metal-to-metal sealing integrity between interconnecting metal 
components. For example, metallic rings are often employed between mating 
components of flanged wellhead assemblies. The flanged components are 
normally bolted together without relative rotation and an annular metal 
ring trapped within circular grooves in the mating flanges provides 
sealing integrity. 
Often metal-to-metal seals must also be established between threaded 
tubular members in a production or completion tubing string and associated 
components. For example, well tools, such as packers, generally comprise a 
plurality of tubular components joined by threaded connections. It is 
often necessary for these threaded connections to maintain pressure 
differentials thereacross. The most common method of providing pressure 
integrity is to use conventional elastomeric O-rings to seal the interface 
of the tubular members adjacent the threaded interconnection. 
Metal-to-metal sealing integrity is also maintained between elastically 
stressed mated threads on certain premium threaded connections employed 
for tubular members used in subterranean oil or gas wells. Premium 
threaded connections are shown in U.S. Pat. Nos. 3,100,656 and 3,185,502. 
U.S. patent application Ser. No. 384,839, filed June 4, 1982, discloses a 
deformable metal-to-metal sealing ring which may be employed between two 
tubular components comprising a downhole tool assembly. That pending 
patent application, assigned to the assignee of the instant application, 
also discloses deformable set down rings for establishing sealing 
integrity between separate elements in a well tool assembly. Axial 
compression is applied to the tubing string to urge the set down ring into 
engagement with a cooperable surface on the well tool assembly. Thus 
metal-to-metal sealing integrity may be established without the use of 
premium threaded connections. The present invention comprises improved 
metal-to-metal seals which may be employed in a subterranean packer or 
similar tool used in conjunction with a tubing seal receptacle for 
permitting tubing movement. 
SUMMARY OF THE INVENTION 
A fluid tight joint for joining two interengagable members, such as two 
threaded tubular members for use as components in a tool used in a 
subterranean oil or gas well, has a transverse surface and a contiguous 
axially extending peripheral, or lateral surface on each member in opposed 
relationship to the transverse and lateral surfaces on the other member. A 
deformable sealing member, such as a deformable ring formed of a material 
softer and more easily deformable than the metallic tubular members, is 
confined between opposed transverse and axially extending peripheral, or 
lateral surfaces upon full interengagement of the tubular members. In the 
preferred embodiment the deformable ring is formed of an extrudable metal. 
Using the metal sealing ring, metal-to-metal sealing integrity is 
initially established along the transverse interface or surface between 
the ring and each tubular member. Upon initial separation or disengagement 
of the tubular members, sealing integrity is maintained along the lateral 
surfaces, at least one of which is inclined relative to the axis of the 
tubular member and relative to the contiguous transverse surface. Sealing 
integrity is maintained because the radial deformation of the sealing ring 
during engagement means that the ring will engage the inclined lateral 
surface during disengagement causing further deformation and maintaining 
continued metal-to-metal sealing integrity. Adequate sealing integrity 
during full engagement and during initial disengagement is assured if the 
ring is confined within a longitudinal sectional area, defined by the 
transverse and lateral surfaces at full engagement, which is equal to or 
less than the longitudinal sectional area of the undeformed ring. Of 
course there will be some axial extrusion through gaps between mating 
tubular members if the ring is larger than the space within which it is to 
be confined. In addition to maintaining sealing integrity, this deformed 
seal ring trapped between relatively inclined lateral surfaces will act to 
resist disengagement of the tubular members which normally occurs in 
response to extraneous mechanical forces resulting from thermal cycling, 
vibration or other causes. Additional torque will be necessary even after 
the threads are initially broken.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The preferred embodiment of this invention is disclosed in use in a 
drillable packer and shear release expansion joint assembly or tubing seal 
receptacle for use in subterranean oil or gas wells under extreme 
conditions of temperature and pressure. The assembly which employs a 
number of metal-to-metal sealed threaded connections. This assembly is 
adapted for use in hostile well environments such as those where the 
bottom hole temperature is in excess of 350.degree. and/or exposed to 
considerable high concentrations of H.sub.2 S and/or CO.sub.2. The packer 
10 is a drillable packer having a radially expandable packing element 90 
positioned between radially expandable anchoring elements 80 and 100. At 
its upper end, the packer is attached to anchor latch 8 which is in turn 
attached to a polished bore tubing seal receptacle 6 extending thereabove. 
An inner mandrel 4 is positioned within polished bore receptacle 6 and is 
attached to the tubing thereabove which extends to the surface of the 
well. 
The conventional attachment between tubing mandrel 4 and the tubing 
extending above the packer expansion joint assembly is not shown in FIG. 
1A. FIG. 1A does show the initial shear pinned position of the mandrel 4 
and the polished bore tubing seal receptacle 6. Shear pin 12 interconnects 
the tubing seal receptacle 6 and mandrel 4 during initial insertion of the 
tubing mounted packer. 
As apparent in FIGS. 1A and 1B, mandrel 4 comprises three separate sections 
4a, 4b and 4c which are joined by conventional threaded connections 32 and 
44. Conventional elastomeric seal assemblies 16a, 16b, 16c, and 16d are 
positioned between oppositely facing shoulders on various components of 
the mandrel 4. For example, seals 16b are positioned between downwardly 
facing shoulder 40 on tubular member 4b and upwardly facing shoulder 38 on 
tubular component 4c. In the preferred embodiment of this invention, these 
seals can comprise elastomeric sealing elements normally impervious to the 
hostile well conditions encountered during operation of this assembly. As 
shown in FIG. 1A, the inner bore of tubing seal receptacle 6 comprises a 
honed or polished surface 14 along which the elastomeric chevron seals 
maintain dynamic sealing integrity during telescoping movement of mandrel 
4 relative to polished bore receptacle 6. 
In addition to the seal established by the resilient polymeric or 
elastomeric chevron seal 16a, 16b and 16c. a metal-to-metal seal is 
established between threaded tubular components comprising inner mandrel 
4. In FIG. 1A, two metal-to-metal seals are shown. Annular seal ring 36 is 
captured between opposed transverse and opposed axially extending 
peripheral or lateral surfaces on tubular components 4a and 4b. The size 
of seal rings 36 and 48 is exaggerated in FIG. 1A for clarity. As threaded 
connection 32 is made-up during interengagement of tubular components 4a 
and 4b, metallic ring 36 is compressed between opposed transverse 
surfaces, one on each tubular component 4a and 4b. Upon full engagement of 
threaded connection 32, a fluid tight metal-to-metal sealing connection 
has been established along the abutting transverse surfaces capturing seal 
ring 36. The laterally extending surfaces, one on each tubular component 
4a and 4b, are inclined relative to the axis of the tubing seal 
receptacle. The opposed lateral surfaces capturing seal ring 36 are 
parallel and the lateral and transverse surfaces define a 
longitudinal-sectional area in the shape of a parallelogram. If ring 36 is 
formed of a material, for example ductile cast iron, which is softer than 
tubular components 4a and 4b and which initially has a rectangular 
longitudinal-sectional configuration, the ring 36 will be plastically 
deformed during makeup of threads 32. As seen in FIG. 1A, the deformed 
longitudinal-sectional configuration of ring 36 is basically a 
parallelogram conforming to the shape of the area between opposed 
transverse and lateral surfaces. 
The inclined lateral surfaces capturing ring 36, which have a projection in 
a plane normal to the tubular axis, bear against the deformed lateral 
surfaces of the ring if there is any tendency for threaded connection 32 
to "back off". Indeed, additional continuous torque after initial breakout 
or disengagement is required to fully disengage the threaded members. 
Forces generated by the bearing engagement of these lateral surfaces also 
tend to lock tubular components 4a and 4b together and prevent back off of 
threaded connection 32. The bearing or sliding contact between inclined 
lateral surfaces also continuously maintain metal-to-metal sealing 
integrity after initial disengagement and during at least partial 
disengagement. Equally important, the deformed ring 36 will remain in 
secure assembly with pin member 4b during disengagement to facilitate the 
removal of the deformed ring 36 and replacement by a new ring for a 
subsequent threaded connection. Since this sealing and mechanical 
integrity is maintained by deformation of ring 36, no appreciable radial 
deformation of the box and pin tubular members occurs. Lack of radial 
deformation is especially important in this application. Radial 
deformation can result if sealing integrity is being maintained by elastic 
deformation of the interengaged threads which occurs with some premium 
thread configurations. If radial deformation results in deflection of the 
inner tubular member of a tubing seal receptacle, the uniform inner 
surface which sliding elastomeric seals 16 move will be disrupted. 
Polished bore receptacle 6 also comprises a plurality of tubular components 
with interengagable threaded connections. The threaded connection 55 
between the bottom end of receptacle 6 and tubular components and 54 
comprises a conventional threaded connection, which is backed up by a 
metal-to-metal deformable seal ring. Seal ring 58 is captured between 
opposed transverse and opposed lateral surfaces in the same manner as seal 
rings 36 and 48. The exact configuration of the surface capturing the seal 
ring 58 may differ from the specfic embodiments of the connections for 
seal rings 36 and 48. Use of deformable seal ring such as ring 58 
establishes sealing integrity for a conventional threaded connection 55. 
As illustrated in FIG. 1C, other means of maintaining metal-to-metal seals 
for threaded connections of tubular components involve the use of a 
premium threaded connection such as that illustrated at 62. Such "premium" 
threaded connections are more elaborate than the simple threaded 
connection such as that depicted at 55. Premium threaded connection 62 is 
configured to have varying threaded surfaces urged together while the 
tubular components are placed in relative compression or tension. These 
premium connections 62 have a generally more elaborate profile than that 
of threaded connection 55 and would normally require a larger 
cross-sectional area for the tubular components. 
The packer itself is shown in FIG. 1F. Packer 10 is similar, although not 
identical, to the packer described and claimed in U.S. Pat. No. 4,326,588. 
Packer 10 employs oppositely facing anchor slip members 80 and 100 adapted 
to engage an exterior conduit, such as the casing C of a well (see FIG. 
3). Cones 82 and 98, having outwardly facing inclined surfaces engage the 
inner inclined surfaces of slips 80 and 100 to urge these slips outwardly 
upon contraction of the packer body. Slips 80 and 100 are thus set in a 
conventional manner. Sealing integrity is established between packer 10 
and the exterior conduit or casing by a packing element 90. In the 
preferred embodiment of this invention, packing element 90 comprises a 
tetrafluoroethylene member (often referred to under the trademark 
"Teflon"), which is noted for its resistance to hostile well environments. 
Secondary sealing or backup members 88 and 92 are positioned on opposite 
ends of Teflon sealing element 90. Backup elements 88 and 92 comprise a 
continuous cylindrical metallic wire mesh. In the preferred embodiment of 
this invention, the wire mesh comprises a seamless, knitted element 
fabricated from a material in filament form such as a steel wire. A 
knitted element of this type is described in U.S. Pat. No. 2,761,203 
entitled "Resilient Gasket Forming Material and Method of Reducing Same", 
and U.S. Pat. No. 3,033,722, entitled "Compressible Metal Gasket and 
Method of Making Same", each being assigned to Metex Corporation of 
Edison, N.J., from which the product can be readily obtained. In the 
configuration depicted herein, the wire mesh serves to prevent extrusion 
of the Teflon element 90 along inner and outer axial flow paths which 
might otherwise permit relaxation of the packing element. Although 
metal-to-metal seal rings are shown in use only in the tubing seal 
receptacle 6, it should be understood that these sealing rings may be used 
between threaded tubular components of the packer itself. 
FIG. 2 is an enlarged view of deformable metal sealing member 36 shown in 
FIG. 1A. Prior to interengagement of threaded connection 32 between 
mandrel section 4a and 4b, the deformable metal sealing element 36, 
normally having a generally rectangular longitudinal-section, can be 
positioned in surrounding relationship to the end of tubular element 4b 
which comprises the pin element of the box and pin connection between 
components 4a and 4b. As the threaded connection 32 is made up, deformable 
sealing member 36 will be trapped between opposed transverse and opposed 
lateral surfaces of the box and pin members. The longitudinal-sectional 
area defined by surfaces 36a, 36b, 36c and 36d, which is generally in the 
shape of a parallelogram with opposed parallel sides, defines an area 
which is less than the undeformed area of deformable metal sealing element 
36. Therefore, element 36 extrudes axially between gaps separating opposed 
surfaces on the box and pin members 4a and 4b upon full engagement of box 
and pin members. When pin member 4b abuts box member 4a along abutting 
surface 5, threaded connection 32 is fully engaged or made up. In the 
fully made up condition box member 4a exerts a pressure on deformable 
sealing member 36 along transverse surface 36a. Similarly pin member 4b 
exerts a pressure along transverse surface 36c. In this condition 
metal-to-metal sealing integrity is established along surfaces 36 a and 
36c. 
The threaded connection of this invention provides for sealing integrity in 
both the fully engaged and the partially disengaged configurations. Under 
normal operating conditions, a threaded connection will tend to relax or 
disengage under the effect of vibrations, thermal cycling, or other 
mechanical forces. Disengagement will result in a loss of sealing 
integrity along the surfaces 36a and 36c during initial disengagement of 
threaded connection 32, because the deformable metallic sealing member 36 
would not possess sufficient memory or elasticity to maintain pressure 
along surfaces 36a and 36c. However, even initial disengagement of 
threaded connection 32 is resisted because of the bearing forces created 
between the deformable sealing member 36 and the box and pin members along 
lateral surfaces 36b and 36d which are inclined relative to the axis of 
the threaded connection. The angle of inclination need not be the same. In 
fact, the inclination of surface 36d on pin member 4b is preferably 
slightly greater than the inclination of surface 36b on box member 4a. By 
choosing the angles in this manner, the deformed ring 36 will be removed 
with the pin member upon complete disengagement of the threaded 
connection. The deformed ring can then be easily replaced with a new 
deformable ring. 
In addition to resisting disengagement of threaded connection 32, the 
bearing contact between threaded members 4a and 4b and the deformable 
member 36 along surfaces 36b and 36d will act as a metal-to-metal seal 
thus providing continuous sealing integrity during and after initial 
thread disengagement. Again in the preferred embodiment of this invention, 
shown in FIG. 2, the volume of the deformable seal member 36 exceeds the 
volume of the parallelogram longitudinal-sectional area defined by 
surfaces 36a, 36b, 36c and 36d to insure initial deformation of the ring. 
Therefore, upon abutment of members 4a and 4b along surface 5 is obtained, 
the sealing member 36 will have extruded beyond the generally 
parallelogram shaped longitudinal-sectional area into the axial extrusion 
gaps, insuring that the deformable member is in contact with surfaces 36a, 
36b, 36c and 36d. The lateral surfaces 36b and 36d are also inclined about 
an acute angle relative to the transverse surfaces 36a and 36c. Therefore, 
during disengagement of the box and pin members 4a and 4b, bearing forces 
are exerted in opposite directions along surfaces 36b and 36d and the 
deformable seal ring will act to maintain sealing integrity upon full or 
subsequent partial engagement of the threaded connection. The inclination 
of surfaces 36b and 36d results in additional deformation of the ring 36 
along bearing surfaces 36b and 36d during disengagement of the threaded 
connection. Contact and sliding or bearing deformation between ring 36 and 
both box and pin members 4a and 4b is the mechanism which assures that 
sealing integrity is continuously maintained. 
In addition to the embodiment shown in FIG. 2, the concept embodied by 
deformable seal ring 36 and its engagement with opposed surfaces within 
which the ring is confined, is equally applicable to other configurations. 
For example, deformable seal ring 58 employed between element 6 and 56 is 
shown in FIG. 1C and in FIG. 3. Note that this embodiment employs a 
similar deformable sealing ring which is again confined within an area 
shaped like a parallelogram and defined by opposed surfaces 58a, 58b, 58c 
and 58d. In this embodiment of the invention there is no abutting surface 
between the two oppositely threadable members 6 and 56, similar to surface 
5 in FIG. 2. In this configuration the threaded connection is made up 
until ring 58 is deformed. Again initial sealing contact is along surface 
58a and 58c. Of course in order to provide axial force along surfaces 58a 
and 58c, the threaded connection 55 located below ring 58 must carry an 
additional axial load. Unlike the embodiment of FIG. 2, the ring 58 shown 
in FIG. 3 will extrude both axially and transversely as threaded 
connection 55 is made up. However, sealing integrity will still be 
maintained along transversely extending surfaces 58a and 58c until initial 
disengagement of threaded connection 55, at which time sealing integrity 
will be similarly maintained along inclined lateral bearing surfaces 58b 
and 58d in the same manner as with the embodiment of FIG. 2. 
This invention is not confined to a configuration in which the 
longitudinal-sectional area of the space confined in the deformable 
sealing ring is in the shape of a parallelogram. For example, FIG. 4 shows 
an alternate embodiment of this invention in which the deformable seal 
ring 458 is initially secured to tubular member 456 by means of a step 
458e. As before, the seal ring 458 is deformed as the threaded connection 
455 is made up with metal-to-metal integrity maintained along surfaces 
458a and 458c. Upon initial disengagement of threaded connection 455, the 
step 458e securing ring 458 to tubular member 456 will tend to move the 
ring with the inner tubular member. Bearing contact will, however, be 
maintained along surface 458b which corresponds to the similar inclined 
surfaces 36b and 58b in FIGS. 2 and 3. As before, sealing integrity will 
be maintained along surface 458b during initial disengagement of threaded 
connection 455. 
FIG. 5 shows still another embodiment of this invention in which the step 
458e of FIG. 4 has been replaced by a separate member 559 engaging both 
ring 558 and inner tubular member 456. Sealing integrity will continue to 
be maintained along surface 558a and 558c until initial disengagement 
again creates a bearing contact along surface 558b. It should be noted 
that separate element 559 can comprise a split C-ring or snap ring and 
need not extend completely around inner tubular member 556. If the torque 
required to disengage threaded connection 555 in the manner described is 
unnecessarily large, element 559 could comprise a shear ring having a 
prescribed shear value. If this prescribed shear value was exceeded prior 
to the point at which the bearing forces along inclined lateral surface 
558b sufficiently deformed ring 558 to permit disengagement of the 
threads, unacceptable levels of torque required to disengage threaded 
connection 555 could be avoided. 
FIG. 6 represents another embodiment of this invention, also having only 
one inclined lateral surface 658b. The inner lateral surface 658d 
comprises an axially extending cylindrical surface. The deformable seal 
ring 658 would not be expected to provide the metal-to-metal sealing 
performance provided by the other embodiments disclosed herein. However, 
the deformation of deformable sealing ring 658a would create an additional 
normal force along surface 658d which would tend to increase the 
frictional force along that surface. Thus this frictional force would act 
in the opposite direction from the bearing force acting along inclined 
lateral surface 658b during initial disengagement of thread 655. 
Therefore, ring 658 would provide a certain degree of metal-to-metal 
sealing integrity during initial disengagement of threaded connection 655. 
Under some conditions the additional metal-to-metal sealing integrity 
provided by the configuration shown in FIG. 6 would be sufficient. 
Unlike the other Figures, FIG. 7 shows a threaded connection prior to 
engagement. FIG. 7 illustrates that the transverse surfaces in the 
embodiment of FIG. 2 or of any of the other embodiments need not be normal 
to the axis of the tubular member. The embodiment of FIG. 7, shown prior 
to complete engagement, corresponds to the embodiment of FIG. 2, except 
that transverse surfaces 700a and 700c of tubular member 704a and 704b are 
inclined relative to the axis of these box and pin members. In FIG. 7, the 
ring 736 has not been deformed since this view shows only the initial 
engagement between the ring and the box and pin members. Therefore, ring 
736 still retains its initial configuration, having a rectangular 
longitudinal section with transverse sides 736a and 736c still 
perpendicular to the axis of the tubular box and pin members 704a and 
704b. As illustrated in FIG. 7, initial contact with ring 736 occurs at 
the corner of transverse surfaces 700a and 700c. Therefore the force per 
unit area exerted on deformable ring 736 will be greater than if the ring 
initial came into flush contact with a perpendicular transverse surface as 
would generally be the case with the embodiment of FIG. 2. Initial 
deformation of the ring in the vicinity of the larger pressure would occur 
more readily, and in addition the force exerted on the ring would have a 
component parallel to transverse surfaces 700a and 700c. The deformable 
ring 736 should therefore slide more easily along surfaces 700a and 700c, 
this permitting the threaded connection 732 to be made up with less torque 
and galling. In addition, it will be easier to establish initial sealing 
integrity during threaded engagement because of the higher loads and 
stresses present in the smaller contact area. As an additional precaution 
against deformation of the metallic tubular members, the inclined lateral 
surfaces merge with axial surfaces 750 and 752. Deformation of the sharp 
corners at the end of the inclined lateral surfaces which might otherwise 
occur after repeated use of the threaded members is thereby avoided. 
Although the invention has been described in terms of the specified 
embodiments which are set forth in detail, it should be understood that 
this is by illustration only and that the invention is not necessarily 
limited thereto, since alternative embodiments and operating techniques 
will become apparent to those skilled in the art in view of the 
disclosure. Accordingly, modifications are contemplated which can be made 
without departing from the spirit of the described invention.