Packer

Details Packer Packer

2000-12-21

2001-11-13

Suchfield, George (Department: 3672)

Wells

Processes

Destroying or dissolving well part

C166S381000, C166S387000

Reexamination Certificate

active

06315050

ABSTRACT:

BACKGROUND
The invention relates to a packer.
As shown in
FIG. 1
, for purposes of measuring characteristics (e.g., formation pressure) of a subterranean formation
31
, a tubular test string
10
may be inserted into a wellbore that extends into the formation
31
. In order to test a particular region, or zone
33
, of the formation
31
, the test string
10
may include a perforating gun
30
that is used to penetrate a well casing
12
and form fractures
29
in the formation
31
. To seal off the zone
33
from the surface of the well, the test string
10
may be attached to, for example, a retrievable weight set packer
27
that has an annular elastomer ring
26
to form a seal (when compressed) between the exterior of the test string
10
and the internal surface of the well casing
12
, i.e., the packer
27
seals off an annular region called an annulus
16
of the well. Above the packer
27
, a recorder
11
of the test string
10
may take measurements of the test zone pressure.
The test string
10
typically includes valves to control the flow of fluid into and out of a central passageway of the test string
10
. For example, an in-line ball valve
22
may control the flow of well fluid from the test zone
33
up through the central passageway of the test string
10
. As another example, above the packer
27
, a circulation valve
20
may control fluid communication between the annulus
16
and the central passageway of the test string
10
.
The ball valve
22
and the circulation valve
20
may be controlled by commands (e.g., “open valve” or “close valve”) that are sent downhole from the surface of the well. As an example, each command may be encoded into a predetermined signature of pressure pulses
34
see (
FIG. 2
) that are transmitted downhole via hydrostatic fluid that is present in the annulus
16
. A sensor
25
may receive the pressure pulses
34
so that the command may be extracted by electronics of the string
10
. Afterwards, electronics and hydraulics of the test string
10
operate the valves
20
and
22
to execute the command.
Two general types of packers typically may be used: the retrievable weight set packer
27
that is depicted in
FIG. 1 and a
permanent hydraulically set packer
60
that is depicted in FIG.
3
. To set the weight set packer
27
(i.e., to compress the elastomer ring
26
to force the ring
26
radially outward), an upward force and/or a rotational force may be applied to the string
10
to actuate a mechanism (of the string
10
) to release the weight of the string
10
upon the ring
26
. However, rotational and translational manipulations of the test string
10
to set the packer
27
may present difficulties for a highly deviated wellbore and for a subsea well in which a vessel is drifting up and down, a movement that introduces additional motion to the test string
10
. Additional drill collars
44
(one drill collar
44
being shown in
FIG. 1
) may be required to compress the ring
26
. Slip joints
46
may be needed to compensate for expansion and contraction of the string
10
.
Referring to
FIG. 3
, the hydraulically set packer
60
may be set by a setting tool that is run downhole on a wireline, or alternatively, the hydraulically set packer
60
may be run downhole on a tubing, and set by establishing a predetermined pressure differential between the central passageway of the tubing and the annulus
16
. Among the differences from the weight set packer
27
, the packer
60
typically remains permanently in the wellbore after being set, a factor that may affect the number of features that are included with the packer
60
. Furthermore, a separate downhole trip typically is required to set the packer
60
. For example, a special tool may be run downhole with the packer
60
to set the packer
60
in one downhole trip, and afterwards, another downhole trip may be required to run the test string
10
. Because the test string
10
must pass through the inner diameter of a seal bore
62
of the packer
60
, the outer diameter of the perforating gun
54
may be limited, and stinger seals
52
of the test string
10
may be damaged.
Thus, there exists a continuing need for a packer that addresses one or more of the above-stated problems.
SUMMARY
In one embodiment of the invention, a packer for use inside a casing of a subterranean well includes a resilient element, a housing and a rupture disk. The resilient element is adapted to seal off an annulus of the well when compressed, and the housing is adapted to compress the resilient element in response to a pressure exerted by fluid of the annulus on a piston head of the housing. The housing includes a port for establishing fluid communication with the annulus. The rupture disk is adapted to prevent the fluid in the annulus from entering the port and contacting the piston head until the pressure exerted by the fluid exceeds a predefined threshold and ruptures the rupture disk.
In another embodiment, a method for setting a packer in a subterranean well includes isolating a resilient element from pressure being exerted from a fluid in an annulus of the well until the resilient element is at a predefined depth in the well. When the resilient element is at the predefined depth, the fluid in the annulus is allowed to compress the resilient element to seal off the annulus.
Advantages and other features of the invention will become apparent from the following description and from the claims.


REFERENCES:
patent: 4216827 (1980-08-01), Crowe
patent: 5170844 (1992-12-01), George et al.
patent: 5320183 (1994-06-01), Muller et al.
patent: 5400855 (1995-03-01), Stepp et al.
patent: 5743335 (1998-04-01), Bussear
patent: 5775428 (1998-07-01), Davis et al.
patent: 5823265 (1998-10-01), Crow et al.
patent: 5921318 (1999-07-01), Ross

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