Wells – Processes – Assembling well part
Reexamination Certificate
2002-04-15
2004-02-24
Neuder, William (Department: 3672)
Wells
Processes
Assembling well part
C166S055800, C166S207000, C072S119000
Reexamination Certificate
active
06695063
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wellbore completion. More particularly, the invention relates to an apparatus and method for expanding a tubular body. More particularly still, the apparatus relates to an expander tool for expanding a section of tubulars within a wellbore.
2. Description of the Related Art
Hydrocarbon and other wells are completed by forming a borehole in the earth and then lining the borehole with steel pipe or casing to form a wellbore. After a section of wellbore is formed by drilling, a string of casing is lowered into the wellbore and temporarily hung therein from the surface of the well. Using apparatus known in the art, the casing is cemented into the wellbore by circulating cement into the annular area defined between the outer wall of the casing and the borehole. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.
It is common to employ more than one string of casing in a wellbore. In this respect, a first string of casing is set in the wellbore when the well is drilled to a first designated depth. The first string of casing is hung from the surface, and then cement is circulated into the annulus behind the casing. The well is then drilled to a second designated depth, and a second string of casing, or liner, is run into the well. The second string is set at a depth such that the upper portion of the second string of casing overlaps the lower portion of the first string of casing. The second liner string is then fixed or “hung” off of the existing casing by the use of slips which utilize slip members and cones to wedgingly fix the new string of liner in the wellbore. The second casing string is then cemented. This process is typically repeated with additional casing strings until the well has been drilled to total depth. In this manner, wells are typically formed with two or more strings of casing of an ever decreasing diameter.
Apparatus and methods are emerging that permit tubular bodies to be expanded within a wellbore. The apparatus typically includes an expander tool that is run into the wellbore on a working string. The expander tool includes radially expandable members, or “expansion assemblies,” which are urged radially outward from a body of the expander tool, either in response to mechanical forces, or in response to fluid injected into the working string. The expansion assemblies are expanded into contact with a surrounding tubular body. Outward force applied by the expansion assemblies cause the surrounding tubular to be expanded. Rotation of the expander tool, in turn, creates a radial expansion of the tubular.
Multiple uses for expandable tubulars are being discovered. For example, an intermediate string of casing can be hung off of a string of surface casing by expanding an upper portion of the intermediate casing string into frictional contact with the lower portion of surface casing therearound. Additionally, a sand screen can be expanded into contact with a surrounding formation in order to enlarge the inner diameter of the wellbore. Additional applications for the expansion of downhole tubulars exist.
An exemplary embodiment of an expander tool previously known as of the filing of this continuation-in-part application is shown in FIG.
1
.
FIG. 1
is an exploded view of an exemplary expander tool
100
.
FIG. 2
presents the same expander tool
100
in cross-section, with the view taken across line
2
—
2
of FIG.
1
.
The expander tool
100
has a body
102
which is hollow and generally tubular. The central body
102
has a plurality of recesses
114
to hold a respective expansion assembly
110
. Each of the recesses
114
has parallel sides and holds a respective piston
120
. The pistons
120
are radially slidable, one piston
120
being slidably sealed within each recess
114
. The back side of each piston
120
is exposed to the pressure of fluid within a hollow bore
115
of the expander tool
100
. In this manner, pressurized fluid provided from the surface of the well can actuate the pistons
120
and cause them to extend outwardly.
Disposed within each piston
120
is a roller
116
. In one embodiment of the expander tool
100
, the rollers
116
are near cylindrical and slightly barreled. Such a roller
116
is sometimes referred to as a “parallel” roller because it includes a side portion that resides parallel to the surrounding tubular to be expanded. Each of the rollers
116
is supported by a shaft
118
at each end of the respective roller
116
for rotation about a respective axis. The rollers
116
are generally parallel to the longitudinal axis of the tool
100
. In the arrangement of
FIG. 1
, the plurality of rollers
116
are radially offset at mutual 120-degree circumferential separations around the central body
102
. In the arrangement shown in
FIG. 1
, two offset rows of rollers
116
are shown. However, only one row, or more than two rows of roller
116
, may be incorporated into the body
102
.
As sufficient pressure is generated on the piston surface behind the expansion assembly
110
, the tubular being acted upon (not shown) by the expander tool
110
is expanded past its point of elastic deformation. In this manner, the inner and outer diameter of the tubular is increased within the wellbore. By rotating the expander tool
100
in the wellbore and/or moving the expander tool
100
axially in the wellbore with the expansion assemblies
110
actuated, a tubular can be expanded into plastic deformation along a predetermined length. Where the expander tool
100
is translated within the wellbore, the shaft
118
serves as a thrust bearing.
One disadvantage to known expander tools, such as the hydraulic tool
100
shown in
FIGS. 1-2
, is the inherently restricted size of the hollow bore
115
. In this respect, the dimension of the bore
115
is limited by the size of the expansion assemblies
110
radially disposed around the body
102
of the tool
100
. The constricted bore
115
size, in turn, imposes a limitation on the volume of fluid that can be injected through the working string at any given pressure. Further, the dimensions of the bore
115
in known expander tools place a limit on the types of other tools which can be dropped through the expander tool
100
. Examples of such tools include balls, darts, retrieving instruments, fishing tools, bridge plugs and other common wellbore completion tools.
In addition, the tubulars being expanded within a wellbore generally define a thick-walled, high-strength steel body. To effectively expand such tubulars, a large cross-sectional geometry is required for the roller body
116
. This further limits the inner bore diameter, thereby preventing adequate flow rates, and minimizing the space available to run equipment through the inner bore
115
. Also, the stresses required to expand the material are very high; hence, reducing the roller body size to accommodate a larger inner bore diameter would mechanically weaken the roller mechanism, thereby compromising the functionality of the expansion assembly.
Therefore, a need exists for an expander tool which provides for a larger configuration for the hollow bore
115
therein. Further, a need exists for an expander tool which reduces the size of the expansion assemblies
110
around the tool
100
so as to allow for a greater bore
115
size. Further, a need exists for an expander tool having expansion assemblies which do not rely upon rollers
116
rotating about a shaft
118
at a spaced apart distance from the piston member
120
.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for expanding a surrounding tubular body. More specifically, an improved expansion assembly for a radially rotated expander tool is disclosed. In addition, a method for expanding a tubular body, such as a string of casing within a hydrocarbon wellbore, is provided, which employs the improved expansion assembly of the present inventi
Lauritzen J. Eric
Mackay A. Craig
Simpson Neil A.A.
Moser, Patterson & Sheridan L.L.P.
Neuder William
Weatherford / Lamb, Inc.
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