U.S. patent number 3,865,188 [Application Number 05/446,422] was granted by the patent office on 1975-02-11 for method and apparatus for selectively isolating a zone of subterranean formation adjacent a well.
This patent grant is currently assigned to Gearhart-Owen Industries, Inc.. Invention is credited to Glenn O. Doggett, Bobby Joe Hallmark.
United States Patent |
3,865,188 |
Doggett , et al. |
February 11, 1975 |
METHOD AND APPARATUS FOR SELECTIVELY ISOLATING A ZONE OF
SUBTERRANEAN FORMATION ADJACENT A WELL
Abstract
A selective completion, or isolation, tool for isolating a
selected zone of subterranean formation adjacent a well,
characterized by modular construction for isolating the zone
regardless of its thickness; a pair of top and bottom inflatable
packer modules and a plurality of modules connected therebetween,
each of the modules having an annular space for circulating cement
and having structural integrity and a plurality of mating half
joints for making up to any predetermined length. Also disclosed
are specific structural embodiments and the methods made practical
by the improved isolation tool.
Inventors: |
Doggett; Glenn O. (Fort Worth,
TX), Hallmark; Bobby Joe (Fort Worth, TX) |
Assignee: |
Gearhart-Owen Industries, Inc.
(Fort Worth, TX)
|
Family
ID: |
23772516 |
Appl.
No.: |
05/446,422 |
Filed: |
February 27, 1974 |
Current U.S.
Class: |
166/285; 166/147;
166/187; 166/276; 166/186; 166/191 |
Current CPC
Class: |
E21B
33/14 (20130101); E21B 33/1243 (20130101); E21B
43/04 (20130101) |
Current International
Class: |
E21B
33/12 (20060101); E21B 33/13 (20060101); E21B
43/02 (20060101); E21B 43/04 (20060101); E21B
33/14 (20060101); E21B 33/124 (20060101); E21b
033/14 (); E21b 043/04 (); E21b 033/124 () |
Field of
Search: |
;166/187,276,285,278,305,295,307,311,308,312,142,147,148,126,127,185,186,224 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Novosad; Stephen J.
Attorney, Agent or Firm: Wofford, Felsman, Fails &
Zobal
Claims
What is claimed is:
1. In apparatus for driling and completing a well penetrating
subterranean formations and having a conduit string therein, a
selective isolation tool for isolating a zone, comprising a
plurality of serially connected modules that include:
a. a plurality of packer modules including at least top and bottom
modules; each of said packer modules including an inflatable packer
element that is expansible when subjected to fluid pressure
therewithin outwardly into sealing contact with the wall of said
well; said packer modules including respective outer tubular
sections carrying said packer elements and concentrically disposed
about respective sections of inner pipe so as to define an annular
passageway therebetween; the respective sections of inner pipe
being adapted to be connected into said conduit string;
b. inflation valve and conduit means connected with said packer
elements and in fluid communication with the interior of said inner
pipe;
c. at least one extension module disposed intermediate and
connected with said packer modules; said at least one extension
module including:
i. a section of inner pipe adapted to be connected sealingly and
serially into said conduit string and having adequate structural
strength to sustain the weight of conduit string therebelow in said
well and sustain the torque of making a connection between
modules;
ii. a section of outer pipe adapted to be connected sealingly and
serially into an outer string of conduit and having adequate
structural strength to sustain the weight of conduit string
therebelow in said well and sustain the torque of making a
connection between modules;
iii. a plurality of force transfer-spacer means connected
respectively with said inner and outer pipes and maintaining them
in fixed concentric and longitudinal relationship with adequate
structural strength to sustain the weight of conduit string
therebelow in said well and sustain the torque of making a
connection between modules; said concentric relationship defining
an annular passageway between said inner and outer pipes; and
iv. interconnection means for connecting respective modules to
contiguous modules; said interconnection means including first and
second mating joint halves, said first joint half being disposed at
one end and adapted for inserting into a second joint half; said
second joint half being disposed at the other end of said extension
module and adapted for receiving said first joint half; said
interconnection means including mating and sealing threaded
sections on one of said sections of pipe and mating longitudinally
slidable and sealing sections on the other of said sections of pipe
such that said extension module can be connected to contiguous
modules by stabbing and screwing only one set of said threaded
sections together and effecting longitudinal sealing
interconnection of both said inner and outer pipes;
whereby any predetermined length isolation tool can be made up and
either said inner pipe can suspend from a travelling block of a rig
and sustain the weight of said conduit string or said outer pipe
can be set with slips on said rig and sustain the weight of said
conduit string and torque necessary to make up said modules of said
isolation tool at said well.
2. The isolation tool of claim 1 wherein said plurality of modules
includes at least one valve module intermediate said packer
modules, said valve module including:
a. a section of inner pipe adapted to be connected sealingly and
serially into said conduit string and having adequate structural
strength to sustain the weight of conduit string therebelow in said
well and sustain the torque of making a connection between
modules;
b. a section of outer pipe adapted to be connected sealingly and
serially into an outer string of conduit and having adequate
structural strength to sustain the weight of conduit string
therebelow in said well and sustain the torque of making a
connection between modules;
c. a plurality of force transfer-spacer means connected
respectively with said inner and outer pipes and maintaining them
in fixed concentric and longitudinally spaced relationship with
adequate structural strength to sustain the weight of conduit
string therebelow in said well and sustain the torque of making a
connection between modules; said concentric relationship defining
an annular passageway between said inner and outer pipes;
d. interconnection means for connecting respective modules to
contiguous modules; said interconnection means including first and
second mating joint halves, said first joint half being disposed at
one end and adapted for inserting into a second joint half; said
second joint half being disposed at the other end of said extension
module and adapted for receiving said first joint half; said
interconnection means including mating and sealing threaded
sections on one of said sections of pipe and mating longitudinally
slidable and sealing sections on the other of said sections of pipe
such that said extension module can be connected to contiguous
modules by stabbing and screwing only one set of said threaded
sections together and effecting longitudinal sealing
interconnection of both said inner and outer pipes;
e. a plurality of laterally extending ports, each defining a
passageway penetrating laterally through said inner and outer pipes
and the annular passageway therebetween; and
f. a valve means having a sealing surface and a valve that
sealingly engages said sealing surface and is selectively movable
into an open position to allow fluid to flow through said ports and
said interior of said inner pipe and into a closed position to
block flow of fluid through said ports; said ports being spaced
apart circumferentially of said pipes and disposed within a
longitudinal distance therealong of less than one foot.
3. The isolation tool of claim 2 wherein said plurality of modules
includes a plurality of said valve modules intermediate said packer
modules; and said valves are individually and selectively movable,
respectively, into said open and closed positions.
4. The isolation tool of claim 3 wherein said valve means is a
sleeve valve means; said sealing surface is defined by a section of
an internal wall of said inner pipe such that said ports penetrate
laterally through said sealing surface; and said valve is a sleeve
valve that is movable to cover and uncover said ports in the
respective closed and open positions; said sleeve valve sealingly
engaging said sealing surface about said ports when covering said
ports and having a length of less than two feet such that said
sleeve valve can be readily moved into its open and closed
positions.
5. The isolation tool of claim 3 wherein said top packer module and
said top valve module are contiguous and are integrally connected
together with the outer tubular section of said packer module being
sealingly and fixedly connected at its bottom end to the top end of
said section of outer pipe of said valve module and with the bottom
end of the section of inner pipe concentrically interiorly of said
outer tubular section of said packer module being integrally
sealingly and fixedly connected to the top end of said section of
inner pipe of said valve module; and a plurality of at least three
spacer means are fixedly disposed intermediate the respective
sections of inner and outer pipe near the bottom of said outer
tubular section so as to maintain an annular passageway through
both said top packer and top valve modules.
6. The isolation tool of claim 2 wherein said first mating joint
half includes a male threaded end on said inner pipe and a male
cylindrical section on said outer pipe; said second mating joint
half includes a female threaded end on said inner pipe and on said
outer pipe a female cylindrical section that conforminly receives
said male cylindrical section; and a seal means is provided
intermediate said male cylindrical section and said female
cylindrical section for sealing when they are slid together in
lateral juxtaposition.
7. The isolation tool of claim 6 wherein said female threaded end
comprises a coupling that is connected to said inner pipe; said
force transfer-spacer means includes at least three lugs that are
welded to said coupling and said outer pipe; said lugs being
angularly spaced apart sufficiently to effect said concentrically
fixed relationship between said inner and outer pipes.
8. In apparatus in a well having a conduit string therein and
penetrating subterranean formations, a downhole isolation tool
isolating a zone of subterranean formation for optimizing
production thereform by any one of a plurality of methods,
comprising a plurality of serially connected modules that
include:
a. a plurality of inflated packer modules including at least top
and bottom modules; said packer modules including respective packer
elements that are sealingly inflated against the wall of a well
near, respectively, the top and bottom of said zone and isolating
said zone longitudinally from the remainder of said well; said
packer modules including respective outer tubular sections carrying
said packer elements and concentrically disposed about respective
sections or inner pipe so as to define an annular passageway
therebetween; the respective sections of inner pipe being connected
into said conduit string adjacent said zone;
b. inflation valve and conduit means holding said packer elements
inflated and preventing flow of fluid into or out of said packer
elements;
c. a set of a plurality of valve modules and extension modules
serially connected together intermediate said packer modules and
connected with, respectively, said top and bottom packer modules;
respective said valve and extension modules including:
i. a section of inner pipe connected sealingly and serially into
said conduit string and having adequate structural strength to
sustain the weight of said conduit string therebelow and sustain
the torque necessary for making and breaking a connection between
one of the casing and the modules;
ii. a section of outer pipe connected sealingly and serially into
an outer tubing string conduit and having adequate structural
strength to sustain the weight of casing therebelow and sustain the
torque of making and breaking said connection;
iii. a plurality of force transfer-spacer means connected
respectively with said inner and outer pipes and maintaining them
in fixed concentric and longitudinal relationship with adequate
structural strength to sustain the weight of said casing therebelow
and sustain the torque of making and breaking said connection; said
concentric relationship defining an annular passageway between said
inner and outer pipes;
iv. interconnection means connecting the respective modules to
contiguous modules; said interconnection means including first and
second mating joint halves with said first mating joint half being
inserted into a second mating joint half; said inter connection
means including mating and sealing threaded sections on one of said
sections of pipe and mating and longitudinally slidable and sealing
sections on the other of said sections of pipe such that said
contiguous modules are sealingly connected via one screwed and
sealing connection and via one longitudinally slidable and sealing
connection;
said valve modules including, in addition:
v. a plurality of laterally extending ports, each defining a
passageway penetrating laterally through said inner and outer pipes
and the annular passageway therebetween; and
vi. a valve means having a sealing surface and a valve that
sealingly engages said sealing surface and is selectively movable
into an open position to allow fluid to flow through said ports and
said interior of said inner pipe and into a closed position to
block flow of fluid through said ports; said ports being spaced
circumferentially of said pipes and disposed within a longitudinal
distance therealong of less than one foot;
a first valve module of said valve modules being disposed adjacent
the top of said zone and a second valve module of said valve
modules being disposed adjacent the bottom of said zone.
9. The downhole isolation tool of claim 8 wherein said conduit
string is casing; said casing is cemented in place by a sheath of
set cement extending for respective distances above and below said
top and bottom packer modules in said well and a sheath of set
cement fills said annular passageway intermediate the respective
sections of inner and outer pipe and said sections of inner pipe
and said outer tubular sections of said packer modules; said first
and second valve modules have their respective valves moved into
respective said open positions; an inner string of tubing extending
from the surface is disposed interiorly of said inner pipe; said
inner string of tubing has a production packer expanded into
sealing contact with the walls of said inner pipe intermediate said
first and second valve modules; and a wash fluid is circulated
through said first and second valve modules and washes flow
restricting material, including drilling mud filter cake, from the
face of said zone intermediate said packer modules; said tubing and
production packer being movable to configure said well for
subsequent fluid flow therethrough.
10. The downhole isolation tool of claim 8 wherein said first and
second valve modules are spaced apart by at least one module
therebetween and are connected with respective top and bottom
packer modules for flowing a fluid effecting a sand control
material radially intermediate said zone and the exterior of said
outer pipe and longitudinally intermediate said inflated top and
bottom packer modules; at least one third valve module having sand
screens emplaced across its said ports is disposed intermediate
said first and second valve modules and connected into said outer
tubular string and said tubular string for producing fluid from
said zone and through emplaced sand control material and blocking
production of sand and similar particulate material; and said
casing is cemented in place by a cement sheath extending for
respective distances above and below said top and bottom packer
modules in said well and a sheath of set cement fills said annular
passageway intermediate the respective sections of inner and outer
pipe and said sections of inner pipe and said outer tubular
sections of said packer modules.
11. The isolation tool of claim 10 wherein a string of tubing
extending from the surface is disposed interiorly of said inner
pipe; said inner string of tubing has a production packer expanded
into sealing contact with the walls of said inner pipe intermediate
said first and second valve modules; said first and second valve
modules have their respective valves moved into respective said
open positions; said at least one third valve modules has its valve
moved into its said closed position; a fluid effecting a sand
control material is circulated through said first and second valve
modules and longitudinally along the face of said zone therebetween
such that said sand control material is effected intermediate said
zone and said exterior of said outer pipe for preventing production
of sand when fluids are produced from said zone; said tubing and
production packer being movable to configure said well for
subsequent production.
12. The isolation tool of claim 11 wherein a column of sand control
material is effected longitudinally intermediate said packer
modules and radially intermediate said zone of formation and said
exterior of said outer pipe; said first and second valve modules
have their valves moved into the respective closed positions and
said at least one third valve module has its valve moved into the
open position for producing fluid through said sand control
material and said sand screens across said ports.
13. Method of cleaning the face of a zone of a subterranean
formation penetrated by a well from the surface comprising the
steps of:
a. running into said well on a conduit string and positioning
adjacent said zone a downhole isolated tool having top and bottom
inflatable packer elements for isolating said zone and a plurality
of selectively and individually openable and closable sets of ports
and valve means; said ports communicating interiorly and exteriorly
of said conduit string and being opened and closed by said valve
means; said inflatable packer elements being concentrically
disposed about said conduit string; a first set of said sets of
ports and valve means being disposed adjacent the top of said zone
and a second set of said sets of ports and valve means being
disposed adjacent the bottom of said zone; said isolation tool
including a string of outer pipe fixedly and concentrically
disposed about a string of inner pipe so as to define an annular
passageway therebetween for circulation of cement therebetween and
about said ports;
b. inflating said packer elements to isolate said zone and emplace
said isolation tool;
c. circulating cement slurry serially through said conduit string,
the annular space between said conduit string and said subterranean
formations for a distance below said isolation tool, the annular
passageway between said inner and outer pipes of said isolation
tool, and the annular space between said conduit string and said
subterranean formations for a distance above said isolation tool;
and allowing said cement to set and cement said conduit string and
said isolation tool in place without contact of said zone with said
cement slurry;
d. after said cement is set; opening said first and second said
sets of ports and valve means;
e. running a string of tubing and a production packer into said
isolation tool; expanding said production packer intermediate said
first and second sets of ports and valve means; and flowing a wash
fluid serially through one of said first and second sets,
longitudinally along and in contact with said zone to wash flow
restricting materials, including drilling mud filter cake and the
like, from the face of said zone, and through the other of said
first and second sets;
f. stopping the flow of said wash fluid; and
g. configuring said well for flow of fluids through the face of
said zone.
14. A method of completing a production well penetrating
subterranean formations in a zone of a formation that normally
produces sand with its production fluids, comprising the steps
of:
a. running into said well, casing containing an isolation tool such
that said isolation tool is positioned adjacent said zone; said
isolation tool having top and bottom inflatable packer elements for
isolating said zone and a plurality of selectively and individually
openable and closable sets of ports and valve means; said ports
communicating interiorly and exteriorly of said casing and being
opened and closed by said valve means; said inflatable packer
elements being concentrically disposed about said casing; a first
set of said sets of ports and valve means being disposed adjacent
the top of said zone and a second set of said sets of ports and
valve means being disposed adjacent the bottom of said zone; at
least one third set of said ports and valve means having sand
screens emplaced across its said ports and being disposed
intermediate said first and second sets of ports and valve means;
said first, second and third sets being closed to block flow of
fluid through said ports; said isolation tool including a string of
outer pipe fixedly and concentrically disposed about a string of
inner pipe so as to define an annular passageway therebetween for
circulation of cement therebetween and about said ports;
b. inflating said packer elements to isolate said zone and emplace
said isolation tool;
c. circulating cement slurry serially through said casing, the
annular space between said casing and said subterranean formation
for a distance below said isolation tool, the annular passageway
between said inner and outer pipes of said isolation tool, and the
annular space between said casing and said subterranean formations
for a distance above said isolation tool; and allowing said cement
to set and cement said casing and said isolation tool in place
without contact of said zone with said cement slurry;
d. after said cement is set; opening said first and second said
sets of ports and valve means;
e. running a string of tubing and a production packer into said
isolation tool, expanding said production packer intermediate said
first and second sets of ports and valve means; and flowing a fluid
effecting a sand control material serially through one of said
first and second sets, longitudinally along and in contact with
said zone for effecting a sand control material and through the
other of said first and second sets;
f. stopping flow of said fluid effecting a sand control material;
and allowing said sand control material to be effected;
g. closing said first and second sets of ports and valve means and
opening said at least one third set of ports and valve means;
and
h. producing fluids from said zone through said sand control
material and said sand screens across the ports of said at least
one third set of ports and valve means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a type of well packer apparatus referred
to as selective completion, or isolation, tools for shielding or
protecting a zone within a well penetrating subterranean formation
and to a method of using the isolation tool for optimizing fluid
flow into or from such zone; for example, for producing oil or gas
from such a zone.
2. Description of the Prior Art
Isolation tools are a type of completion tools that have packer
elements at their top and bottom ends. Such isolation tools
employing the inflatable packer elements are known. They are useful
in completing an oil well to produce fluid from a given zone after
drilling is complete and are beneficial in preventing contact of
the producing zone with the cement that is employed to cement the
casing in place. In addition, such isolation tools having
respective valve means have eliminated costly perforations of the
casing and consequent damage to the casing and cement by explosive
charges. Other advantages of the inflatable packer type isolation
tools have been realized through reduction of completion time and
expense, use of the tools in series to reduce chances of
communication between close producing zones and selected
stimulation and testing of a well during the completion
operation.
The closest prior art of which we are aware are U.S. Pat. Nos.
3,194,312 and 3,456,725. The equipment of the former patent employs
many matching portholes and a long production control valve inside
the tool for aligning portholes. A possible disadvantage of this
tool is that the portholes allow sand to accumulate and block
movement of the long production valve. Moreover, the valve moves in
a unitary way and does not provide selectively openable and
closable sets of ports or portholes. Equipment described in the
latter patent uses short inflatable packers that are located on the
ends of concentrically spaced sleeves to effectively seal off the
formation. It, too, has valves that are opened at a predetermined
pressure and not thereafter closable. Moreover, the valves open
simultaneously such that the ports are not selectively and
individually controllable to allow the flexibility that is
desirable. With the equipment of both of the prior art patents, the
total length of the tool is limited by the height of the derrick
that is used to install it since the tools are unitary tools and
must be pre-prepared to a predetermined length. For example, it
thus has been impossible heretofore to provide such a tool for
isolating a zone that was thicker than the drilling rig was tall.
This in effect limited such tools to isolating zones of less than
about 90 feet, since most drilling rigs cannot handle longer
sections of conduit.
We have found it advantageous that an isolation tool have the
following features not heretofore provided by the prior art.
1. The tool should be modular in concept such that any length tool
can be assembled at the well site, yet have an annular passageway
between inner and outer pipe and through the tool for circulation
of cement.
2. Each of the modules should have structural integrity to suspend
the weight of the conduit therebelow by either the inner pipe or
the outer pipe.
3. The modules should have at their respective ends, joint halves
that can be joined to form an interconnection means in which only
one set of threads need to be made up and still effect a sealing
connection of respective sections of both the inner and outer
pipes.
4. The isolation tool should have a plurality of valve modules that
have individually and selectively openable and closable valves for
controlling the flow through ports therethrough and allow the
flexibility of washing the formation, emplacing sand control
material, or producing from or injecting into the formation.
Accordingly, it is an object of this invention to provide an
isolation tool having one or more of the forgoing features not
heretofore provided by the prior art, thereby alleviating the
difficulties of the prior art.
It is another object of this invention to provide an isolation tool
having all of the delineated features not heretofore provided by
the prior art; and to provide methods of employing the isolation
tool for optimizing flow of fluids through the well.
It is a specific object of this invention to provide an isolation
tool that is economical and easy to transport and install; that can
be assembled at the well site in as long an isolation tool as
desired, even sufficient to cover zones thousands of feet in
thickness, without being limited to the height of the rig with
which they are being installed; and that has a plurality of
production control valves that are respectively, individually and
selectively openable and closable and to provide a high degree of
flexibility, including at least two different methods of operation
employing the added flexibility not heretofore possible.
These and other objects will become apparent from the following
descriptive matter, particularly when taken in conjunction with the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A, 1B and 1C are respective cross sectional elevational
views of the top and bottom sections of the isolation tool and the
lower end of a string of conduit having the isolation tool
connected thereinto; all in a pre-emplacement configuration within
the well.
FIGS. 2A, 2B and 2C are respective cross sectional elevational
views of the embodiment of FIGS. 1A, 1B and 1C and show the
emplaced configuration after the packers have been inflated.
FIG. 3 is a cross sectional view taken along the lines III--III of
FIG. 1B.
FIG. 4 is a longitudinal cross sectional view showing an
interconnection means of the embodiment of FIGS. 1A and 1B being
made up, or connected.
FIG. 5 is a cross sectional elevational view, partly schematic, of
another embodiment of this invention being employed to circulate a
fluid across the face of an isolated zone intermediate inflated
packers.
FIG. 6 is a cross sectional elevational view, partly schematic, of
an embodiment of this invention similar to that of FIG. 5, but
configured to produce fluid from the zone through the production
ports intermediate the top and bottom ports.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIGS. 1A and 1B, the selective completion, or
isolation, tool 11 is shown positioned within a wellbore 13 that
has been drilled into subterranean formation in a conventional
manner. The isolation tool 11 is shown connected into a
conventional tubular string of conduit, such as casing 15; the
bottom end 17 thereof being illustrated in FIG. 1C in a typical
embodiment. The isolation tool 11 is positioned in the wellbore 13
adjacent a zone 19 that is to be isolated. The zone 19 may be a
producing subterranean formation or a zone that is producing an
objectionable fluid, such as water, into a wellbore that is being
drilled by air or gas drilling or the like; or any other zone that
needs to be isolated for whatever reason. The limits of the zone
19, such as the impermeable upper and lower formations 21 and 23
may be delineated by suitable logs, such as produced by a gamma ray
logging tool. The zone 19 may be substantially homogeneous, such as
a sand stone, or may have discontinuous and inhomogeneous strata or
vugs 25 therein. One advantage of this invention is that the zone
19 may have any thickness; for example, many times the height of a
conventional drilling rig being used to run the casing 15 into the
wellbore 13.
In any event, the isolation tool 11 is so formed that the packer
modules will be positioned for effecting, when inflated, isolation
of the zone 19 longitudinally from the remainder of the wellbore
13; for example, opposite the impermeable strata 21 and 23. If
desired, any zone within a subterranean formation of even
encompassing several subterranean formations can be isolated by
proper placement of the packer modules.
The isolation tool 11 includes a plurality of serially connected
modules, as indicated hereinbefore. At the top and the bottom of
the serially connected modules are the top and bottom packer
modules 27 and 29. The packer modules 27 and 29 have respective
expansible packer elements in the form of inflatable jackets 31.
The packer modules also include respective outer tubular sections,
or sleeves, 33 that carry the respective inflatable jackets 31. The
inflatable jackets 31 may be formed of any suitable material; for
example, from Nylon reinforced rubber, such as Neoprene, that is
resistant to wellbore fluids. The inflatable jackets 31 with their
integral steel clamps, or bands, 35 at their respective ends are
premanufactured and slipped into the outer tubular sections 33.
Suitable seals, such as o-rings 37, are interposed between the
respective steel bands 35 and the outer tubular sections 33 to
ensure that no fluid is lost when the jackets 31 are inflated.
Retainer rings 38 are thereafter welded in place to hold the
inflatable jackets against the shoulders 40 at their other end. The
process of inflating the jackets is frequently referred to as
"inflating the packers" and is also referred to herein as
"inflating the packer modules" as a shorthand description of the
complete process.
For inflating the inflatable jackets 31, the respective packer
elements include conduit means, such as tube 39. The tubes 39 are
connected with respective check and block valves 41; and, thence,
with suitable inflation valves 43.
The check and block valves 41 allow fluid to flow through the tube
39 to inflate the inflatable jacket 31 up to a predetermined
pressure. After the predetermined pressure is reached, suitable
means, such as a shear pin, is sheared, or released, and a valve
block moved to close off the ports and prevent flow of fluid into
or out of the inflated jacket 31. The check and block valves 41 are
conventional and need not be described in detail herein; being
described, for example, in U.S. Pat. No. 3,456,725.
The inflation valve 43 may comprise any of the conventional
inflation valves. As illustrated, the inflation valve 43
communicates interiorly of the casing 15 by way of a shear-off
cover 45. The cover 45 is sheared off by any suitable means; such
as, a wireline tool or a plug pumped down the casing 15 under
pressure; to open the tube 39 to the fluid pressure interiorly of
the casing 15.
The tubular sections 33 that carry the inflatable jackets 31 are
fixedly concentrically disposed about respective sections of inner
pipe 47 and 49. Thus, the respective outer tubular sections 33 and
the sections of inner pipe 47 and 49 define respective annular
passageways through the respective packer modules 27 and 29 for
circulation of cement therethrough. As can be seen, the inflation
valves 43 at their shear-off covers 45 penetrate laterally through
the walls of the respective sections of inner pipe 47 and 49 so the
tubular sections 33 and the respective sections of inner pipe 47
and 49 also are fixed longitudinally with respect to each other, as
will become apparent from descriptive matter later hereinafter. The
respective sections of inner pipe 47 and 49 are adapted for being
connected into the conduit string. Specifically, the top of the
section of inner pipe 47 and the bottom of the section of inner
pipe 49 have conventional threads for being threadedly connected
into a coupling, such as coupling 51, FIG. 1A.
To provide the desired length of isolation tool to effect placement
of valve modules at the top and bottom of the zone 19, a plurality
of modules, such as extension modules 53 and valve modules 55, are
serially connected together in a set intermediate the top and
bottom packer modules 27 and 29. The ends of the set of the
plurality of modules are connected, respectively, with the top and
bottom packer modules 27 and 29. As many of the respective modules
as desired can be made up at a well site as the conduit, such as
the casing 15, is lowered into the wellbore 13. Ordinarily, the
respective modules have certain features in common that facilitate
the preparation of the isolation tool of the desired length and
with the desired placement of the valve modules 55. For example,
the respective extension and valve modules 53 and 55 include the
following common structural features that are illustrated most
clearly with respect to the extension module 53 in FIGS. 1A, 1B, 3
and 4. They include a section of inner pipe 57; a section of outer
pipe 59; a plurality of force transfer-spacer means, such as ribs,
or lugs, 61; and interconnection means 63 connecting the respective
modules to contiguous modules.
The respective sections of inner pipe 57 are connected sealingly
and serially into a string of inner pipe and the conduit string,
such as casing 15, as by threaded connection. The respective
sections of inner pipe 57 have adequate structural strength to
sustain the weight of the conduit string therebelow in the well and
sustain the torque of making up a connection between the modules on
the drilling rig floor. For example, when being suspended from a
travelling block on a rig, each section of inner conduit 57 must be
able to support the weight of the casing 15 therebelow.
The respective sections of outer pipe 59 are connected sealingly
and serially into an outer string of conduit, as by threaded
connection. The sections of outer pipe 59, similarly as the
sections of inner pipe 57, have adequate structural strength to
sustain the weight of conduit string therebelow in the well and
sustain the torque of making a connection between modules. For
example, as will be described with respect to FIG. 4 hereinafter,
when set with slips 64 on the floor 65 of a rig, the respective
sections of outer pipe 59 must be able to withstand the weight of
the conduit string therebelow, as well as sustain the torque of
making up a connection between the modules.
Ordinarily, the same type of steel pipe that is being employed for
the casing 15 is employed for the respective sections of inner and
outer pipe 57 and 59; only the diameter is different so as to
define an annular passageway 67 therebetween. The annular
passageway 67 is provided for circulation of a cement slurry for
cementing the isolation tool in place in the wellbore 13, as will
become apparent hereinafter.
At least three ribs, or lugs, 61 are fixedly connected,
respectively, with the sections of inner and outer pipe 57 and 59
for maintaining them in fixed concentric and longitudinal
relationships. Thus, the lugs 61 maintain the annular passageway
67. The lugs 61 are connected, as by welding, so as to have
adequate structural strength and sustain the weight of the conduit
string therebelow in the well and sustain the torque of making a
connection between modules and be able to transfer the stress to
either the inner or the outer pipe as appropriate. As illustrated,
the lugs 61 are welded onto a coupling 69 and are inserted to a
point opposite a weld-through aperture 71, FIG. 1B. The coupling 69
forms a section of greater strength than the remainder of the
section 57 of inner pipe and affords a better base for the
connection of the lugs 61. The aperture 71 is employed for
convenience in welding the lugs 61 to the section of outer pipe 59.
The aperture 71 is then filled with metal, further enhancing the
strength of the force transfer-spacer means formed by the lugs
61.
The interconnection means 63 includes first and second mating joint
halves 73 and 75. The first mating joint half 73 is inserted into
the second mating joint half 75. Specifically as illustrated, the
top of the respective sections of inner pipe 57 have a female
threaded section, such as defined by coupling 69, for receiving a
male threaded connection. As illustrated, the respective sections
of inner pipe 57 are threadedly connected with the coupling 69 by
way of threaded interconnection 87. In like manner, the bottom end
of the respective sections of inner pipe 57 have a male threaded
section 77 that conformingly screws into a sealing fit with the
coupling 69.
The top of the section of outer pipe 59 has a female cylindrical
section 79 that conformingly receives a male cylindrical section 81
that is formed onto the bottom of the contiguous module thereabove.
Specifically, the female cylindrical section 79 comprises a
precisely formed annular recess having a smooth interior surface
for sealing. In like manner, the male cylindrical section 81 is
formed by a sub 83 that is connected with the bottom end of the
section 59 of outer pipe of the contiguous module thereabove and
has a precisely formed, smooth male cylindrical surface for
sealing. The sub 83 may be connected onto the bottom end of the
section of outer pipe 59 by any suitable means, such as by welding.
A resilient seal means, such as o-rings 85, are provided
intermediate the laterally juxtaposed female and male sealing
cylinders 79 and 81 to ensure a sealing interconnection
therebetween.
As illustrated in FIG. 4, in connecting the modules the male
threaded section 77 of this embodiment is screwed almost into its
sealing position; for example, lacking only about five rounds of
thread; before the male cylindrical section 81 begins to be
inserted within the female cylindrical section 79. This reduces the
wear on the resilient seal means as compared with having to
rotatingly engage the interior surface of the female cylindrical
section 79 throughout the entire rotation of the respective
threaded section 77 in the coupling 69.
An annular passagway 67 is defined circumferentially about the
coupling 69 and interiorly of the sub 83 for circulation of cement
through the interconnection means. Thus, any one of the modules can
be readily connected with any one of the contiguous modules by the
simple expedient of making up one threaded connection,
simultaneously effecting a sealing interconnection between the
respective sections of inner and outer pipe so as to form a
continuous string of inner and outer pipe with the annular
passageway 67 therebetween for circulation of cement slurry,
regardless of the length of isolation tool.
In addition to the structural features that are common to both the
valve modules and the extension modules, the valve modules 55 also
include a plurality of laterally extending ports 91 and a valve
means 93, FIG. 1B. The plurality of laterally extending ports each
define a passageway penetrating laterally through the respective
sections of inner and outer pipe 57 and 59 and the annular
passageway 67 therebetween. The plurality of laterally extending
ports 91 are spaced apart circumferentially about the section of
inner and outer pipes 57 and 59; and within a distance of less than
one foot along the respective sections of inner and outer pipe 57
and 59 in order that the valve means can be operated into the
closed or open position. This obviates one disadvantage of the
prior art apparatus that required moving a long section of valve
means with the attendant danger that it will become sanded up and
immovable. As illustrated, a plurality of eight ports 91 are
disposed in a single plane such that they occupy only about the
diameter of the ports; namely, about 3/4 to 1 inch. Any number of
ports may be employed as desired. Ordinarily, about the minimum
that will be employed will be four diametrically opposed ports 91.
We have found that about eight ports affords a nearly ideal number
although as many as 16 or more may be employed if they are
staggered. The ports may be opened for production of fluids or
injection of fluids therethrough. They may have suitable
accessories, such as sand screens 95, FIGS. 5 and 6, emplaced
thereacross. The sand screens 95 may take any of the conventional
forms. For example, they may comprise the conventional cylindrical
sand screens that are affixed in place, as by welding, about the
circumference of the section of outer pipe 59. On the other hand,
they may comprise so-called "finger screens." The finger screens
are emplaced in the respective ports 91 and have many small
apertures penetrating longitudinally of the screens and laterally
through the ports 91. These finger screens are ordinarily formed of
ceramic or other material that is resistant to both corrosion and
erosion, or abrasion; yet are foraminous, or permeable, to the flow
of fluids therethrough. They may be emplaced by any suitable means,
such as C-clamps or mounting rings screwed into the respective ends
of cylindrical ports 91.
The valve means 93 includes a sealing surface 97 and a valve 99
that sealingly engages the sealing surface and is selectively
movable into an open position to allow fluid to flow through the
ports 91 and the interior of the section of inner pipe and into a
closed position to block flow of fluid through the ports.
Specifically, the sealing surface 97 is illustrated as being formed
on a portion of inner wall of the section of inner pipe 57 and
terminates at each end in internal thread 101 into which are
screwed the mating ends 103 of the remainder of the section of
inner pipe 57. The sealing surface 97 is carefully formed as an
elongate cylinder for slidably receiving a sleeve valve; and is
polished so as to be smooth for effecting a good seal when engaged
by the valve 99. As illustrated, the valve 99 comprises a mating
sleeve valve having respective seal means, such as o-rings 105,
embedded in annular grooves in its peripherally outermost surface
for ensuring a seal with the sealing surface 97. The valve 99 has
an internal large annular recess 107 intermediate its ends for
receiving dogs 109, FIGS. 6, for being moved into its respective
open and closed positions. The dogs 109 are operable between a
disengaged, or retracted, position in a valve operating tool 111
for passing through the respective sleeve valves, such as sleeve
valve 99A, FIG. 5. The dogs may then be selectively expanded into
their engaging, or expanded, position, such as illustrated in FIGS.
5 and 6. The dogs may be operated by any suitable means; such as,
by electric motor by relative motion between the external section
108 held by drag springs 110 and an inner section 112 rotated by
tubing 113. The valve operating tool is normally run into the well
on a suitable string, such as tubing 113.
The respective modules may be slightly modified to form specialty
combinations of two or more of the modules that are most frequently
employed. For example, it is ordinarily advantageous to have a
double module with a valve module 55A, FIG. 1A, at the top of a
respective zone 19 adjacent the top packer module for either
washing the face of the zone adjacent the wellbore 13, effecting a
sand control material, or for producing or injecting fluids through
the face of the zone. Such a widely used double module modification
is illustrated in FIG. 1A in which the top valve module 55A is
integrally formed with the top packer module 27. Therein, the
section of inner pipe 47 of the packer module 27 is threadedly
connected into the internal thread 101 of the section of inner pipe
57 of the valve module 55A adjacent the sealing surface 97.
Thereafter, the respective sections of inner pipe that are
threadedly connected together are also welded to ensure they do not
become separated or leak. In a similar manner, the bottom end 115
of the outer tubular section 33 is sealingly emplaced interiorly of
a female top end 117 of the section of outer pipe 59. A joinder
ring 119 is employed to reinforce the joint and the top and bottom
ends are then welded together similarly as were the interior
threaded ends of the inner pipe. A plurality of lugs 61 are fixedly
connected, as by welding, to the respective sections of inner and
outer pipe so as to maintain their concentric relationship defining
the annular passageway 67.
Typically, the bottom end of the casing will terminate in a sub
that contains a receptacle 121, FIG. 1C, for receiving a pump-down
plug, as well as a check valve 123. After a pump-down plug 125 and
ball 131 is received, the ball 131 is sheared out at a
predetermined pressure after the packer elements are inflated, FIG.
2C.
In operation, the bottom packer module 29 is connected into the
conduit string, such as casing 15. The bottom packer module 29 has
at its top end a coupling 69 and female cylindrical section 79
ready to receive the next contiguous section. Thereafter, the next
contiguous module, such as valve module 55, is stabbed into the top
of the bottom packer module 29 and screwed into place,
simultaneously effecting sliding sealing interconnection between
the outer tubular section 33 and the section of outer pipe 59.
Similarly, the next contiguous module, such as extension module 53,
will be stabbed into and sealingly connected with the top of the
valve module 55. The remaining plurality of modules will be
similarly serially and sealingly connected together to effect the
desired length and placement of the respective modules in the
isolation tool 11. Finally, the top valve module 55A and the top
packer module 27 will be stabbed and sealingly connected with the
top of the extension module 53, as illustrated in FIG. 1A. The
remainder of the casing is thereafter threadedly connected together
and until the desired length is achieved sufficient to emplace the
top and bottom packer modules 27 adjacent the impermeable strata 21
and 23 defining the limits of the zone 19 and against which the
respective packers can be inflated to seal and isolate the zone 19.
In the run-in, or pre-emplacement, configuration the respective
valves 99 are in their closed positions for effecting a desired
pressure interiorly of the sections of inner pipe and casing
15.
As illustrated in FIGS. 2A, 2B and 2C, a pump-down plug 125 is
thereafter pumped down the casing 15, shearing the shear-off covers
45 from the inflation valves 43. The pump-down plug 125 comes to
rest in the pump down receptacle 121, FIG. 2C. Thereafter, pressure
is effected by pumping the fluid down the interior of the casing
15, inflating the respective inflatable jackets 31 of the packer
modules 27 and 29 so they sealingly engage against the respective
impermeable strata 21 and 23 at the wall of the wellbore 13. When a
predetermined pressure has been reached, the check and block valves
41 close, thereafter preventing fluid flow into or out of the
inflated jackets 31. For example, at about 250 pounds per square
inch (psi) a shear pin in each check and block valve 41 is sheared,
trapping the fluid in each inflated packer.
Thereafter, the casing pressure can be increased up to 1,000 psi or
more to shear a pin in the pump-down plug, release a plug ball 131
and allow cement to be circulated. The cement slurry is circulated;
for example, downwardly through the casing and back up through the
annular space between the casing and the wall of the wellbore 13,
as well as through the annular passageway 67 through the isolation
tool. The cement slurry may be circulated completely back to the
surface or for only a predetermined distance above and below the
isolation tool 11. In this way the face of the formation is
isolated from contact with a cement slurry to prevent the resultant
damage that frequently occurs from such cementing operations.
Thereafter, a valve operating tool 111 is lowered through the
casing 15 and the respective valves 99 are moved as desired to
configure the well for flow of fluids therethrough. For example,
the valves 99 may be moved into their open positions such that the
respective ports 99 produce fluids from the zone 19 into the
interior of the casing 15. If desired, the fluids may be produced
through the casing. It is common practice in producing operations,
however, to insert tubing 113 with a production packer 133 to
protect the casing and force the fluids to flow upwardly through
the tubing 113, as illustrated in FIG. 6. The production packers
133 are well known and need not be described in detail herein. It
is sufficient to note that they ordinarly have a resilient seal 135
that can be expanded into sealing contact with the interior of the
section of inner pipe 57. If set above open valves 99, the set
production packer isolates the annular passageway intermediate the
exterior of the tubing 113 and the interior of the casing 15 and
constrains fluid to flow through the tubing 113. If set between
open valves 99, the production packer converts the annular
passageway into a separate and return flow passageway for
circulation of fluid flowed downwardly through the interior of the
tubing 113.
If desired, the valve operating tool 111 may be suspended by any
other suitable means, such as by wireline, for moving the
respective valves 99 into their open position by pulling upwardly
thereon. Conversely, if the valves are to be moved into their
closed position, a wireline with jars suspending the valve
operating tool 111 is employed. In the latter case, the dogs 109
are expanded into the recess 107 and the valve closed by jarring
downwardly thereon.
One advantage of this invention is that a variety of different
embodiments of the isolation tool can be prepared for a great
flexibility in operation. For example, the respective top and
bottom packer modules may be employed with only extension modules
therebetween if it is desired to isolate a formation that is
producing water into a well being drilled by air or gas drilling.
If, on the other hand, subsequent control of flow of fluids into or
from the isolated zone 19 could be necessary, it is advisable to
employ one or more valve modules. Ordinarily, the valve modules
will be disposed at least near the top and bottom of the formation,
particularly where it is desired to wash the face of the formation
to rid it of flow restricting material, such as drilling mud filter
cake and the like; effect sand control material; or otherwise treat
the zone 19. Thus, in an isolation tool similar to that illustrated
in FIGS. 2A and 2B, the tubing 113 with the valve operating tool
111 and the production packer 133 may be emplaced interiorly of the
casing 15 and the respective top and bottom valves; similar to
valves 99A and 99B, FIGS. 5 and 6; will be moved into their open
positions.
Thereafter, a wash fluid is flowed serially through one of the open
top or bottom valves, longitudinally along and in contact with the
face of the zone 19 to wash flow-restricting materials from the
face of the zone and through the other of the open ports. For
example, as illustrated in FIG. 5, the wash fluid is circulated
downwardly through the tubing 113, outwardly through open ports
91B, along the face of the formation and back inwardly through the
top open ports 91A and, thence, upwardly in the annular passageway
between the tubing 113 and the section of inner pipe 57 and the
casing 15. After the zone has been suitably washed, the tubing and
production packer may be moved upwardly within the casing above the
open top valve 99A and fluids produced through the tubing 113. If
desired, the intermediate valve 99C may be opened in FIG. 5,
although it is not shown in the embodiment of FIGS. 2A and 2B. If,
on the other hand, the well is to be completed as an injection
well, fluids may be injected downwardly through the tubing 113 and
into the isolated zone 19. The production packer 133 will be
emplaced above the top open valve 99A so as to constrain the flow
of fluid interiorly of the tubing 113 when the tubing and
production packer are employed.
If desired, of course, the tubing may be employed alone without the
production packer 133 and such open annulus completions are
sometimes advantageous in helping to unload a well, as by injecting
gas into the annulus to blow liquids up the tubing and prevent
liquid loading that would stop production.
In any event, the isolation tool of this invention can be employed
in any of the usual well configurations, whether injection or
production, and still achieve its advantages as delineated in more
detail hereinafter.
Another embodiment that is frequently useful in zones 19 that
normally produce sand with their production fluids may be
understood by referring to FIGS. 5 and 6, specifically. Therein,
the top valve 99A and the bottom valve 99B are moved into their
open positions as described hereinbefore, leaving the intermediate
valve module 55C with its valve 99C in the closed position. As can
be seen, the top and bottom sets of ports 91A and 91B do not have
any sand screens 95 in place whereas the at least one intermediate
set of ports 91C do have the sand screens 95 emplaced therein, or
extending across the ports. Moreover, while only one intermediate
valve module 55C is illustrated, as many as desired may be employed
for effecting the requisite length tool and the requisite
production capability for producing fluids from the zone 19. After
the isolation tool has been emplaced and cemented into place as
described hereinbefore and the respective top and bottom valve
modules opened, as illustrated, a fluid effecting a sand control
material is circulated past the face of the zone 19; for example,
downwardly through the tubing 113, upwardly across the face of the
zone 19, back in through the top ports 91A and thence upwardly
through the annular space between the tubing and the casing.
The terminology "fluid effecting a sand control material" is
employed herein, even though it is awkward; since there are a wide
variety of different types of sand control materials that are
effected by different ways. For example, the oldest and simplest is
the so-called gravel pack in which gravel or sand within a
controlled size range are injected in a carrier fluid and allowed
to settle in the annular space between the exterior surface of the
sections of outer pipe 59 and the face of the zone 19 and
intermediate the top and bottom packer modules 27 and 29. This is
the embodiment that is illustrated in which the gravel 139 is
illustrated emplaced in FIG. 6. It should be readily appreciated,
however, that any of the fluids effecting sand control material may
be employed. For example, a fluid may be flowed along and into the
passageways of the face of the formation to set and consolidate the
sand grains at their points of contact and prevent movement of the
sand toward the wellbore, yet allow fluid to be produced through
the open pores and passageways therebetween. This type of sand
consolidation material may take a wide variety of forms from those
fluids that are set by heat, such as furfural alcohol and the like,
to those catalytically set agents, such as the epoxy resins,
regardless of whether the latter employ a time-setting single fluid
or another and catalyst-containing fluid to effect the desired
setting. Typical of the wide variety of sand control agents that
are conventional and well known are the following: Sand Bond I-IV:
Sandpoxy I-VI; Eposand 9 S; Eposand 112 S; Comp-slurry; Slurry-pack
C; Comp-perm C; Exxon E; Continental C; Shell S; Chevron CH and the
like. In fact, any fluid that will not pass through the 3/4 and 1
inch ports 91A and 91B would probably not be satisfactory in
effecting a satisfactory sand control material.
In any event, after the sand control material has been effected, by
whatever means that is appropriate, the top and bottom valves 99A
and 99B are moved into their closed positions, as illustrated in
FIG. 6. The one or more intermediate valves 99C are moved into
their respective one or more open positions, opening the production
ports 91C for flow of fliuds through the sand screens 95. Similarly
as described hereinbefore, the production packer 133 is emplaced
above the uppermost open set of ports 91C so as to constrain the
production fluids to flow through the tubing 113 rather than the
annular space between the tubing 113 and the casing 15. This method
of production is advantageous in that the fluids from the zone 19
are constrained to flow through the sand control material,
illustrated as gravel pack 139, and through the sand screens 95
such that problem with production of sand is alleviated.
If desired, a plurality of respective sets of ports in one or more
valve modules may have different sand screens with different size
openings or materials or forms of construction emplaced across
their respective ports 91 such that empirical data will indicate
the best type of sand screen, or size openings, that need to be
employed for optimizing production. No other tool has this
flexibility.
The respective modules may be prepared in any predetermined lengths
that are easily assembled. For example, the extension modules
having various lengths of 2, 4, 6, 8. . . up to 24 feet in length
are employed in facilitating making up an isolation tool having the
desired length and placement of the valve and packer modules. The
valve modules may have any length; for example, in the range of 2-6
feet. A variety of lengths are not particularly helpful, since the
valve module has one primary function. We have found that a length
of about 3 feet is satisfactory. The packer modules, similarly as
the valve modules, may have any length, but ordinarily do not need
to vary as much as the extension modules. Packer modules 2-6 feet
in length have been found adequate to sealingly engage respective
subterranean formations. Ordinarily, a packer module having a
packer element about two feed in length is satisfactory.
The respective elements of the isolation tool 11 may be made of any
material that will satisfy the requirements delineated hereinbefore
for the respective elements.
While an inflatable jacket has been disclosed as the packer element
for the packers, the packers may take any other suitable form; for
example, a concentric bag that sealingly seats at its radial
interior against the outer tubular section 33 and expands outwardly
into contact with the wall of the wellbore 13.
Any of the conventional inflation valves may be employed, not only
the use of inflation valves having shear-off covers. For example,
pressure responsive inflation valves may be employed to inflate the
packers only after a predetermined pressure has been reached.
While the respective packer modules 27 and 29 have been illustrated
as having their own individual inflation valves 43 and check and
block valves 41, a single inflation valve 43 and check and blocck
valve 41 may be employed in tubing 39 that extends to both the top
and bottom packers 27 and 29 if desired. This structure may be
advantageous when shorter tools are made up. It is ordinarily
preferable, however, to have the illustrated structure wherein
respective packer sections have their own respective inflation
valve and conduit means and the modules may be freely made up
without having to bother about the tube running longitudinally of
the annular passageway 67.
The three lugs 61 spaced 120.degree. apart circumferentially with
respect to the inner and outer pipes have been described. Any
number of lugs may be employed as long as they effect the
concentric relationship between the inner and outer pipes. For
example, four lugs, spaced 90.degree. apart, may be employed if
desired.
While the threaded sections of the interconnection means have been
described hereinbefore as being on the sections of inner pipe, they
could be emplaced on the outer pipe if desired and the respective
longitudinally slidable and sealing sections be formed on the
sections of inner pipe. The same desirable results are achieved in
which a sealing interconnection is made between both the sections
of inner and outer pipe with making up only one threaded
connection.
While a coupling 69 has been illustrated hereinbefore as the female
threaded section that is connected to the respective sections of
inner conduit by way of threaded connection 87, it is apparent that
the female threaded section may be formed integrally with the
remainder of the section of inner pipe 57, if desired.
While a sleeve valve and a cylindrical sealing surface have been
described hereinbefore for the respective valve means for
controlling flow of fluid through the ports 91, any other valve
means may be employed as desired. For example, it has been found to
be advantageous in certain high pressure installations to employ
planar ports and ball plugs that engage respective spherical
sealing surfaces for controlling the flow of fluid through the
ports. Such ball valves are conventional and need not be described
in detail herein.
From the foregoing, it can be seen that this isolation tool is
advantageous in that is has the features delineated hereinbefore
and not heretofore provided by the prior art. This isolation tool
has wide applicability since it is extremely flexible and may be
employed in a wide variety of applications.
Specifically, this isolation tool or selective completion tool,
permits completion of a well without cement contaminating any of
the producing interval; without perforating, since the large ports
allow adequate flow without any perforating and since there is no
cement sheath around the casing; and without plugging and squeeze
cementing each zone that is tested. This isolation tool allows the
capability of quickly shutting in any zone without requiring
killing of the well, provides the ability to clean the entire face
of the production interval and provides a better chance of
producing what the drill stem tests indicate the zone is capable of
producing. Moreover, the entire formation face is available to
accommodate any particular type of treatment that is desired,
whether it be merely washing the formation or effecting deposition
of a sand control material, such as a sand consolidation material,
or any other remedial work. The isolation tool allows fluid to be
produced from the entire formation face instead of only the area
about a few perforations and effects much better drainage of the
zone with lower pressure drop in the immediate vicinity of the
wellbore. From a safety point of view, the valves are able to be
closed in the casing to shut in a well, in addition to being
individually and selectively openable and closable for optimizing
production -- these features not being available in any other tool.
Since the ports are large diameter ports; for example, 3/4 to 7/8
inch or more, it is possible to achieve high injectivity, whether
for acid treatment, water-flood or fracturing with low hydraulic
horsepower requirements.
The isolation tool allows a wide variety of special applications in
addition to those delineated hereinbefore. For example, lost
circulation zones may be isolated to allow continued drilling;
zones producing corrosive fluids, such as hydrogen sulfide, may be
isolated to protect the remainder of the casing from damage, with
or without an openable valve therein for later setting a pancake or
other type of protection out in the formation if desired; and
multiple tubingless completions may be effected, if desired. As
indicated hereinbefore, however, a primary benefit of this
isolation tool is that long thicknesses of zones, or producing or
injection intervals, can be isolated and configured for flow of
fluid easily at the well site because of the modular construction
and the other structural features delineated hereinbefore.
From the foregoing, it can be seen that this invention achieves the
objects delineated hereinbefore.
Although this invention has been described with a certain degree of
particularity, it is understood that the present disclosure has
been made only by way of example and that numerous changes in the
details of construction and the combination and arrangement of
parts may be resorted to without departing from the spirit and the
scope of this invention.
* * * * *