Wells – Packers or plugs – Expanded by confined fluid from central chamber – pump or...
Reexamination Certificate
2000-06-01
2002-09-10
Schoeppel, Roger (Department: 3672)
Wells
Packers or plugs
Expanded by confined fluid from central chamber, pump or...
C166S374000, C166S383000, C166S387000
Reexamination Certificate
active
06446717
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for sealing between two or more surfaces. Specifically, the present invention relates to an expandable packer for sealing oil field wellbores.
2. Background of the Related Art
FIG. 1
is a schematic view of a typical oil field well
10
. A wellbore
12
is drilled through the strata
16
and a casing
14
is inserted therein to maintain the integrity of the wellbore for subsequent production of hydrocarbons from beneath the surface of the well. Typically, a replaceable tubing string
18
, comprising a plurality of tubes that are longitudinally connected together, is inserted into the casing
14
to a certain depth in the well, such that the lower end of the tubing string is proximate a production zone
20
containing hydrocarbons. Perforations
22
are formed in the casing at the depth of the formation to be produced to allow the hydrocarbons to enter the wellbore
12
through the casing
14
. In many cases, it is desirable that the hydrocarbons flow to the surface through the tubing string
18
to avoid corrosion and flow damage to the casing
14
. In those cases, a sealing assembly, such as a packer
23
, may be run on the lower end of the tubing string
18
. The packer
23
seals an annulus between the tubing outside diameter and the casing inside diameter, thereby diverting the hydrocarbons to flow through the tubing to the surface. In other examples, a packer seal is effected inside the tubing string
18
and can be referred to as a plug. Alternatively, the packer may seal an annulus between a smaller tubing string (not shown) outer diameter and the tubing string
18
inner diameter.
FIG. 2
is a schematic cross sectional view of one commercially available permanent type packer
23
. The packer is shown in a disengaged state, i.e., “running position”, on the left side of the schematic view and in an engaged state, i.e., “set position”, on the right side of the view. The packer
23
includes a packer body
24
having a ridge portion
25
. A lock ring housing
26
is disposed in an upper portion of the packer
23
. A lock ring
43
is disposed between the lock ring housing
26
and the ridge portion
25
. The lock ring
43
includes mating ridges
27
adjacent the ridges on the ridge portion
25
. At least one upper slip
28
and typically a plurality of slips are disposed below the lock ring housing
26
and include a serrated outer surface where the serrations are typically referred to as wickers
29
. The upper slip
28
is disposed about the circumference of the packer
23
and are used to hold the packer in position when the wickers
29
grip the casing
14
. An upper cone
30
is disposed below the upper slip
28
. The upper cone
30
includes a tapered surface
41
that mates with a corresponding tapered surface on the upper slip
28
. The upper cone
30
is used to displace the upper slip
28
radially outward as an axial force is applied to the slip
28
in a direction toward the upper cone. A pair of backup rings
31
,
32
is disposed below the upper cone
30
and includes tapered surfaces that allow the backup rings to be displaced toward the casing
14
during “setting” of the packer into a sealing position. A seal ring
33
is disposed below the backup ring
32
. A deformable packing element
34
is disposed below the seal ring
33
and is typically an elastomeric material that can be axially compressed and radially expanded toward the casing
14
to effect a seal. A corresponding arrangement of elements is disposed below the packing element
34
as is disposed above the packing element. The arrangement of members below the packing element includes a seal ring
35
, a pair of backup rings
36
,
37
, a lower cone
38
having a tapered surface
42
, and a lower slip
39
having wickers
40
.
To set the packer
23
, mechanical or hydraulic methods can be used and are well known in the art. Regardless of the method used to set the packer, generally the objective is to lower the packer attached to a tubing string to a setting depth and axially compress the assembly of external components relative to the packer body. The axial compression causes at least a portion of the external components, such as the slips
28
,
39
and the packing element
34
, to expand radially outward into engagement with the casing
14
. The lock ring housing
26
and the lock ring
43
are forced along the ridge portion
25
of the packer body
24
as the slips and the packing element are radially expanded. When the desired amount of longitudinal compression is reached, the ridges on the ridge portion
25
in cooperation with the ridges
27
on the lock ring
43
maintain the lock ring and the lock ring housing
26
in the set position. The wickers
29
,
40
of the slips
28
,
39
“bite” into the casing surface to hold the packer
23
in position.
Elastomeric materials are frequently used for the packing element
34
and other sealing elements because of the resiliency of the elastomeric materials. However, under certain adverse conditions, elastomeric elements may be insufficient for the duty. Adverse conditions such as high temperatures, high pressures, and chemically hostile environments are common in downhole oil field wells that produce hydrocarbons. For example, the temperatures and/or pressures can cause extrusion of elastomeric elements and can result in leakage past the packer after installation. Another problem associated with elastomeric elements is “swab off”, where a pressure differential between two surfaces of the elastomeric element, such as the inner and outer surfaces, can deform the element and cause the element to become dislodged from the tool during run-in.
Providing a ductile metal as the packing element has been suggested as one solution to the failure of elastomeric elements. Thus, a “metal to metal” contact is theoretically made between, for example, the packing element and the casing inside diameter that is less prone to extrusion under such adverse circumstances. However, typical manufacturing tolerances of the casing leading to nonconformities, such as the casing ovality, typically reduce the sealing capabilities of the metal to metal contact and leakage can result. Further, even if an initial seal occurs, the seal may leak under changing conditions of temperature and/or pressure, because the metal is not sufficiently resilient.
Prior efforts, such as shown in U.S. Pat. No. 2,519,116, incorporated herein by reference, to effect metal to metal contact have employed detonating explosive charges disposed on a rod within a packer cavity to expand an outer ductile metal wall of the packer. The expanded metal wall engages the casing and forms a metal to metal contact. However, once deformed from the explosion, the cavity is no longer able to expand to meet changing conditions.
Further, U.S. Pat. No. 2,306,160, also incorporated herein by reference, teaches a fluid injected into a cavity to inflate the cavity and effect a seal. The reference discloses that suitable liquid materials injected into the cavity are those liquids which harden after expansion and, thus, are unable to meet changing conditions.
Therefore, there remains a need for a metal sealing assembly with increased sealing capabilities and sufficient resiliency, particularly under adverse conditions in an oil field well.
SUMMARY OF THE INVENTION
The invention generally provides a sealing assembly with a deformable portion and a core at least partially disposed within the deformable portion that can be radially expanded to engage an adjacent surface and effect a seal. In one embodiment, the core is a fluid-containing core that preferably comprises a compressible fluid and the deformable portion comprises a deformable metal. The core can retain an amount of stored energy and adjust to changing conditions that otherwise might affect the seal integrity. The core can be sealed within the deformable portion and can be compressed by a force applied to the deformable portion to cause radial expansion.
Eriksen Erik P.
Haugen David M.
White L. Cameron
Moser, Patterson & Sheridan L.L.P.
Schoeppel Roger
Weatherford / Lamb, Inc.
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