U.S. patent application number 10/347166 was filed with the patent office on 2003-12-18 for system for running tubular members.
Invention is credited to Allamon, Jerry P., Miller, Jack E., Waggener, Kenneth D..
Application Number | 20030230405 10/347166 |
Document ID | / |
Family ID | 29740747 |
Filed Date | 2003-12-18 |
United States Patent
Application |
20030230405 |
Kind Code |
A1 |
Allamon, Jerry P. ; et
al. |
December 18, 2003 |
System for running tubular members
Abstract
The present invention relates to a wiper plug and internal drop
ball mechanism that may be used in conjunction with a downhole
surge reduction tool to run, hang, and cement casing liners in a
wellbore. The apparatus of the present invention comprises a wiper
plug assembly removably attached to the drill string within the
casing liner, a drop ball sub attached below the wiper plug
assembly which releases a float valve actuator ball having a
diameter larger than the drill string, and float equipment having a
plurality of flapper valves. The apparatus of the present invention
may further comprise a diverter tool connected between the drill
string and the casing liner.
Inventors: |
Allamon, Jerry P.;
(Montgomery, TX) ; Miller, Jack E.; (Houston,
TX) ; Waggener, Kenneth D.; (Houston, TX) |
Correspondence
Address: |
Jerry P. Allamon
2040 N. Loop 336, Suite 126
Conroe
TX
77304
US
|
Family ID: |
29740747 |
Appl. No.: |
10/347166 |
Filed: |
January 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10347166 |
Jan 17, 2003 |
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10337404 |
Jan 6, 2003 |
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10337404 |
Jan 6, 2003 |
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09850247 |
May 7, 2001 |
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6513590 |
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09850247 |
May 7, 2001 |
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09829107 |
Apr 9, 2001 |
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6491103 |
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Current U.S.
Class: |
166/193 ;
166/177.3 |
Current CPC
Class: |
E21B 33/16 20130101;
E21B 43/10 20130101 |
Class at
Publication: |
166/193 ;
166/177.3 |
International
Class: |
E21B 033/12 |
Claims
What is claimed is:
1. A drop ball mechanism for use within a tubular member being run
on a drill string in a wellbore containing drilling fluid,
comprising: a wiper plug assembly releasably connected to the drill
string within the tubular member near the top of the tubular
member; and a drop ball housing connected to the wiper plug
assembly below the wiper plug assembly and having an axial bore
therein and a set of flow holes formed therein for establishing
communication between the axial bore of the drop ball housing and
the tubular member below the wiper plug assembly, said drop ball
housing including a drop ball having a diameter greater than the
inside diameter of the drill string, said set of flow holes having
a diameter to permit the creation of a pressure differential
between the axial bore of the drop ball housing and the tubular
member below the wiper plug assembly when drilling fluid is pumped
from the drill string into the drop ball housing, said pressure
differential being of sufficient magnitude to cause the drop ball
to release from the drop ball housing.
2. The drop ball mechanism of claim 1, wherein the tubular member
comprises float equipment attached to the tubular member near the
bottom of the tubular member, said float equipment having an axial
bore through which drilling fluid may flow, said axial bore having
a diameter greater than the inside diameter of the drill string,
said float equipment including a plurality of flapper valves which
are activated by the drop ball after it is released from the drop
ball housing.
3. The drop ball mechanism of claim 2, wherein the wiper plug
assembly has an axial bore therethrough and a receptacle in the
axial bore for receiving a drill pipe dart.
4. Apparatus for running a tubular member in a wellbore containing
drilling fluid using a drill string, comprising: a running tool
connected to the top of the tubular member and having an axial bore
therethrough; float equipment attached to the tubular member near
the bottom of the tubular member, said float equipment having an
axial bore therethrough which drilling fluid and cement may flow,
said axial bore having a diameter greater than the inside diameter
of the drill string, said float equipment including a plurality of
flapper valves; a wiper plug assembly releasably connected to the
drill string within the tubular member near the top of the tubular
member, said wiper plug assembly having an upper end, a lower end,
and an axial bore formed therethrough, said wiper plug assembly
having a receptacle in said axial bore for receiving a drill string
dart to release the wiper plug assembly from the drill string and
to move the wiper plug assembly downward to engage the float
equipment; and a drop ball mechanism connected to the lower end of
the wiper plug assembly, said drop ball mechanism including a
releasable drop ball having a diameter greater than the inside
diameter of the drill string, said drop ball being released to
activate the flapper valves of the float equipment once the wiper
plug assembly engages the float equipment.
5. The apparatus of claim 4, wherein the drop ball mechanism
further comprises a drop ball housing for releasably connecting the
drop ball to the lower end of the wiper plug assembly, said drop
ball housing having a set of flow holes formed above the drop ball
through which drilling fluid may flow into the bore of the wiper
plug.
6. The apparatus of claim 5, further comprising a diverter tool
connected between the drill string and the running tool, said
diverter tool having an open port position and a closed port
position, said diverter tool being in the open port position during
the running in of the tubular member.
7. The apparatus of claim 4, wherein the diverter tool comprises: a
housing connected to the drill string, said housing having a set of
housing flow holes formed therein; a sleeve within the housing
having a set of sleeve flow ports formed therein; said sleeve being
initially positioned within the housing such that an open port
position exists; a yieldable drop ball seat connected to the
sleeve; and an axial indexing means to move the sleeve between the
open port position and the closed port position.
8. The apparatus of claim 4, further comprising a wiper plug
release mechanism for releasing the wiper plug from the drill
string, said release mechanism comprising: a plurality of fingers
which are formed on the end of the drill string such that an
opening exists between each adjacent finger, said fingers having
lower outer ends that have wedge-shaped surfaces for engagement
with the dart receptacle of the wiper plug; and a yieldable,
circular flat washer in the wiper plug which supports the
receptacle and which allows the fingers to disengage from the
receptacle when the dart is received and when pressure is increased
behind the dart.
9. Apparatus for running a tubular member in a wellbore containing
drilling fluid using a drill string, comprising: a running tool
connected to the top of the tubular member and having an axial bore
therethrough; float equipment attached to the tubular member near
the bottom of the tubular member, said float equipment having an
axial bore therethrough which drilling fluid and cement may flow,
said axial bore having a diameter greater than the inside diameter
of the drill string, said float equipment including a plurality of
flapper valves; an upper liner wiper plug assembly having an upper
end which is releasably connected to the drill string within the
tubular member near the top of the tubular member, a lower end, and
an axial bore formed therethrough, said upper liner wiper plug
assembly including a receptacle in said bore for receiving a drill
string dart; a lower liner wiper plug assembly having an upper end
which is releasably connected to the lower end of the upper liner
wiper plug assembly, a lower end, and an axial bore formed
therethrough, said lower liner wiper plug assembly including a
receptacle in said bore for receiving a drill string dart to
release the lower liner wiper plug assembly from the drill string
and to move the lower liner wiper plug assembly downward to engage
the float equipment; and a drop ball mechanism connected to the
lower end of the lower liner wiper plug assembly, said drop ball
mechanism including a releasable drop ball having a diameter
greater than the inside diameter of the drill string, said drop
ball being released to activate the flapper valves of the float
equipment once the lower liner wiper plug assembly engages the
float equipment.
10. The apparatus of claim 9, further comprising a diverter tool
which is connected between the drill string and the running tool,
said diverter tool having an open port position and a closed port
position, said diverter tool being in the open port position during
the running in of the tubular member.
11. The apparatus of claim 10, wherein the diverter tool comprises:
a housing which is connected to the drill string, said housing
having a set of housing flow holes formed therein; a sleeve within
the housing having a set of sleeve flow ports formed therein, said
sleeve being initially positioned within the housing such that an
open port position exists; a yieldable drop ball seat which is
connected to the sleeve; and an axial indexing means to move the
sleeve between the open port position and the closed port
position.
12. The apparatus of claim 10, wherein the upper liner wiper plug
is releasably connected to the drill string by a mechanism which
comprises: a plurality of fingers which are formed on the end of
the drill string such that an opening exists between each adjacent
finger, said fingers having lower outer ends that have wedge-shaped
surfaces for engagement with the dart receptacle of the upper liner
wiper plug; and a yieldable, circular flat washer in the upper
liner wiper plug which supports the receptacle and which allows the
fingers to disengage from the receptacle when the dart is received
and when pressure is increased behind the dart.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation-in-part of U.S.
patent application Ser. No. 10/337,404 filed Jan. 6, 2003, which
was a continuation of U.S. patent application Ser. No. 09/850,247
filed May 7, 2001, which was a continuation-in-part of U.S. patent
application Ser. No. 09/829,107 filed Apr. 9, 2001, now U.S. Pat.
No. 6,491,103.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an apparatus for running
tubular members such as drilling/production liners or subsea casing
strings in a wellbore. More particularly the present invention
relates to a wiper plug and internal drop ball mechanism that may
be used in conjunction with the running and cementing of such
tubular members in a wellbore.
[0004] 2. Description of the Prior Art
[0005] In oilfield applications, a "casing liner,"
"drilling/production liner," and a "subsea casing string" are
tubular members which are run on drill pipe. The terms "casing
liner" and "drilling/production liner" are usually used with
respect to drilling operations on land, while the term "subsea
casing string" is used with respect to offshore drilling
operations. For ease of reference in this specification, the term
"liner" is used to denote either a "casing liner," a
"drilling/production liner," or a "subsea casing string."
[0006] Prior art drop ball-actuated float equipment for use in
cementing liners in place includes, for example, a float shoe or
float collar which has one or more flapper valves and which is
located at or near the bottom of the liner. The flapper valve or
valves are conventionally held open by a breakable plastic tab
which is actuated (i.e., broken) by a drop ball when the cementing
operation is to begin. The industry has traditionally used systems
where a drop ball is released at the surface, and the drop ball
must be small enough in diameter to pass through the smallest
restriction in the drill string, which usually is the diameter of
the bore in the running tool. The size of such restrictions has,
therefore, limited the maximum size of the opening in a float
collar or shoe. In the case of a 133/8" liner, the maximum diameter
of a drop ball is somewhere between 2 and 3 inches. Due to the
small diameter bore of traditional float equipment and the highly
contaminated environment in which such equipment is used, the
valves in traditional float equipment tend to become plugged with
cuttings and contaminants.
[0007] As a liner is lowered into the wellbore, the fluid in front
of the liner must be displaced to flow through the opening in the
float equipment as well as around the outside annulus defined by
the wellbore and the liner. The flow resistance of the two flow
paths may be high and thus causes a pressure known as surge
pressure to build up below the liner. This surge pressure can: (a)
cause damage to the formation; (b) result in loss of expensive
drilling fluid; and (c) result in the liner sticking against the
side of the borehole, which means the liner does not go to the
bottom of the hole.
[0008] U.S. Pat. No. 5,960,881, which is incorporated herein by
reference, discloses a downhole surge pressure reduction system to
reduce the pressure buildup while running in a tubular member such
as a casing liner. The system is typically located immediately
above the top of the casing liner. Nonetheless, any plugging of the
float equipment at the lower end of the casing liner can, and very
well may, render the surge pressure reduction system of the '881
patent ineffective.
[0009] The method and apparatus according to the present invention
overcomes the plugging problem and allows enhanced passage of fluid
through the tubular member and into the surge pressure reduction
tool.
SUMMARY OF THE INVENTION
[0010] In accordance with the present invention, apparatus is
provided for running a tubular member through a wellbore containing
drilling fluid using a drill string.
[0011] Apparatus in accordance with the present invention comprises
a running tool connected to the top of the tubular member having an
axial bore therethrough.
[0012] Apparatus in accordance with the present invention further
comprises a wiper plug assembly which includes a wiper plug
releasably suspended from a running tool within the tubular member
and a receptacle sleeve to receive a drill pipe dart. During
cementing operations, the wiper plug assembly receives the drill
pipe dart and is released from the drill string at the top of the
tubular member. The wiper plug assembly is then pumped downward
forcing cement out of the bottom of the tubular member and into the
annulus between the tubular member and the borehole.
[0013] One end of the wiper plug assembly is connected to the
running tool attached to the tubular member. The running tool for
the wiper plug comprises an axially indexing sleeve and a plurality
of wedge-shaped fingers which releasably engage the wiper plug
receptacle sleeve. During running in of the tubular member, the
drilling fluid flows from the tubular member upward through the
ports between the fingers and into the void above the wiper plug
fins. To isolate the wiper plug fins from internal pressure during
cementing operations, the drill pipe sleeve is indexed axially
downward to block the ports between the fingers.
[0014] Apparatus in accordance with the present invention also
comprises a drop ball sub attached to and below the wiper plug
assembly within the tubular member. The drop ball sub releases a
float equipment actuator ball which is larger in diameter than the
smallest restriction in the drill string. When released, the
actuator ball drops to the bottom of the tubular member where it
actuates float equipment. Once actuated, flapper valves in the
float equipment prevent the back flow of cement traveling downward
through the tubular member.
[0015] Apparatus in accordance with the present invention may
further comprise a surge pressure reduction device or diverter tool
connected between the drill string and the running tool. When the
diverter tool is in an open port position, the drilling fluid may
flow upward from inside the diverter tool into the annulus between
the casing cemented in place and the drill string. When in a closed
port position, the device provides passage for fluid to travel
downward through the drill string.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In the accompanying drawings:
[0017] FIG. 1 is an elevation view of an, embodiment of the system
of the present invention for running of a tubular member
downhole.
[0018] FIG. 2 is an elevation view of an embodiment of the present
invention illustrating flow path of the drilling fluid facilitating
surge pressure reduction as tubular member is run downhole.
[0019] FIG. 3 is an elevation view of an embodiment of the present
invention illustrating a drop ball seated in a yieldable seat of
surge reduction apparatus with the ports of that apparatus in open
position.
[0020] FIG. 4 is an elevation view of an embodiment of the present
invention illustrating the surge reduction apparatus of FIG. 3 with
the ports of that apparatus in closed position.
[0021] FIG. 5 is an elevation view of an embodiment of the present
invention illustrating second drop ball seated in yieldable seat of
a collet finger sleeve with the ports in open position.
[0022] FIG. 6 is an elevation view of an embodiment of the present
invention illustrating the collet finger sleeve blocking the collet
finger ports.
[0023] FIG. 7 is an elevation view of an embodiment of the present
invention illustrating the drop ball seated in yieldable seat of a
drop ball sub apparatus with the port of that apparatus in open
position.
[0024] FIG. 8 is an elevation view of an embodiment of the present
invention illustrating a flapper valve actuator ball being forced
through a yieldable seat and drop ball sub apparatus with ports in
closed position.
[0025] FIG. 9 is an elevation view of an embodiment of the present
invention illustrating the flapper valve actuator ball engaging a
float collar.
[0026] FIG. 10 is an elevation view of an embodiment of the present
invention illustrating a drop ball being pressured through
yieldable seat in the drop ball sub apparatus.
[0027] FIG. 11 is an elevation view of an embodiment of the present
invention illustrating a dart being pumped downhole behind
cement.
[0028] FIG. 12 is an elevation view of an embodiment of the present
invention illustrating the dart of FIG. 11 being pumped downward
through drill string and engaging a seat in a wiper plug
assembly.
[0029] FIG. 13 is an elevation view of an embodiment of the present
invention illustrating a wiper plug assembly being wound downward
through a tubular member and forcing cement downward through float
equipment, out of tubular member, and upwards into annulus between
tubular member and formation.
[0030] FIG. 14A is an enlarged section view of the wiper plug
assembly with collet fingers engaging wiper plug upper flange.
[0031] FIG. 14B is an enlarged section view of the dart engaging
wiper plug assembly with collet fingers moving radially inward and
releasing wiper plug.
[0032] FIG. 15 is an elevation view of an embodiment of the present
invention illustrating a dual wiper plug apparatus.
[0033] FIG. 16 is an enlarged section view of the latching
mechanism connecting the upper liner wiper plug to the lower liner
wiper plug.
[0034] FIG. 17 is an enlarged section view of the latching
mechanism as it releases the lower liner wiper plug from the upper
liner wiper plug.
[0035] FIG. 18 is an elevation view of an embodiment of the present
invention without an actuator ball sleeve illustrating flow path of
the drilling fluid facilitating surge pressure reduction as tubular
member is run downhole.
[0036] FIG. 19 is an elevation view of an embodiment of the present
invention without an actuator ball sleeve illustrating the drop
ball resting on the actuator ball with the collet finger sleeve
blocking the collet finger ports.
[0037] FIG. 20 is an elevation view of an embodiment of the present
invention without an actuator ball sleeve illustrating a flapper
valve actuator ball being forced through a yieldable seat.
[0038] FIG. 21 is an enlarged section view of the four plug
embodiment of the present invention illustrating the drop ball
seated in yieldable seat of a drop ball sub apparatus with the port
of that apparatus in open position.
[0039] FIG. 22 is an enlarged section view of the four plug
embodiment of the present invention illustrating the drop ball
seated in yieldable seat of a drop ball sub apparatus with the port
of that apparatus in closed position.
[0040] FIG. 23 is an enlarged section view of the four plug
embodiment of the present invention illustrating a dart being
pumped downward through drill string and engaging a seat in the
lower liner wiper plug assembly.
[0041] FIG. 24 is an enlarged section view of the four plug
embodiment of the present invention illustrating the latching
mechanism as it releases the lower liner wiper plug from the upper
liner wiper plug and moving axially downward to engage the float
equipment.
[0042] FIG. 25 is an enlarged section view of the four plug
embodiment of the present invention illustrating actuator ball
engaging the float equipment.
[0043] FIG. 26 is an enlarged section view of the four plug
embodiment of the present invention illustrating the actuator ball
activating the flapper valves of the float equipment.
DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION
[0044] A description of certain embodiments of the present
invention is provided to facilitate an understanding of the
invention. This description is intended to be illustrative and not
limiting of the present invention. In the appended claims, the term
"tubular member" is intended to embrace either a "casing liner," a
"subsea casing string," or a "drilling/production liner."
[0045] With reference first to FIG. 1, the general components of a
system are illustrated in which apparatus in accordance with the
present invention is used. A mast M suspends a traveling block TB.
The traveling block, in turn, supports a top drive TD which moves
vertically on a block dolly BD. An influent drilling fluid line L
supplies the top drive TD with drilling fluid from a drilling fluid
reservoir (not shown). A launching manifold LM connects to a drill
string S. The drill string S comprises numerous pipes which extend
down into the borehole BH, and the number of such pipes is
dependent on the depth of the borehole BH. A flow diverting device
B is connected between the bottom end of drill string S and the top
of running tool 162. A tubular member, such as casing liner 161, is
suspended from running tool 162. Float equipment, e.g. float collar
160, is fastened near the bottom of the casing liner 161.
[0046] Solidified cement CE1 fixes a surface casing SC to the
surrounding formation F. The surface casing SC contains an opening
O in the uppermost region of the casing adjacent to the top. The
opening O controls return of drilling fluid as it travels up the
annulus between the drill string S and the surface casing SC.
[0047] Solidified cement CE2 fixes an intermediate casing IC to the
surrounding formation F. The intermediate casing IC is hung from
the downhole end of the surface casing SC by a mechanical or
hydraulic hanger H.
[0048] The annulus between the drill string S and the intermediate
casing IC is greater in area than the annulus between the casing
liner 161 and the intermediate casing IC. While the present
invention is not intended to be limited to use in tight or close
clearance casing runs, the benefits of the present invention are
more pronounced in tight clearance running, since as the area is
reduced and the pressure (pressure is equal to weight/area) is
increased.
[0049] Referring now to FIG. 2, apparatus in accordance with the
present invention comprises running tool 162 which is connected to
the top of casing liner 161 and which has an axial bore
therethrough. In one embodiment of the present invention, a flow
diverter tool B is removably connected between drill string S and
running tool 162, and in another embodiment of the present
invention, no such diverter tool is employed. Diverter tool B, when
used, is preferably a diverter device as disclosed in the '881
patent. The diverter tool B comprises a housing 183 having at least
one housing flow port 169A, a yieldable seat 173, and a sleeve 170
having at least one sleeve flow port 169B. When diverter tool B is
in the "open port position," sleeve 170 is arranged such that
housing flow port 169A and sleeve flow port 169B are aligned. This
provides passage for drilling fluid to flow from inside of housing
183 to annulus between drill string S and the cemented in place
casing 205. When the diverter tool B is in the "closed port
position," sleeve 170 has been indexed axially downward so that
housing flow port 169A and sleeve flow port 169B are not axially
aligned and the flow passage is blocked.
[0050] Wiper plug assembly WP is suspended inside casing liner 161
from running tool 162 by the running tool S2 for the wiper plug,
one end of which is connected to running tool 162. As described in
U.S. patent application Ser. No. 09/541,526, file Apr. 3, 2000, the
wiper plug WP is releasably connected to the second end of the
running tool S2 by collet fingers 168. The openings or ports
between collet fingers 168 provide communication to the void above
wiper plug fins 163. Drilling fluid flowing upward from drop ball
sub 166 to flow diverter device B passes through the ports between
collet fingers 168 and fills the void above wiper plug fins 163.
When casing liner 161 has been lowered to full depth, sleeve 171
may be indexed axially downward to block flow through the ports
between collet fingers 168, thereby isolating the wiper plug fins
163 from internal pressure.
[0051] Drop ball assembly DB is attached to the bottom of wiper
plug assembly WP. The drop ball assembly DB comprises a housing 166
having at least one housing flow port 167A, a yieldable seat 175, a
sleeve having at least one sleeve flow port 167B, an actuator ball
201, and a second yieldable seat 176. Before the release of
actuator ball 201, sleeve 172 is arranged in the "open port
position" such that housing flow port 167A and sleeve flow port
167B are aligned. These aligned ports provide a passage for
drilling fluid to flow as discussed below.
[0052] Float equipment 160, which may for example be a float
collar, is located at or near the bottom of casing liner 161 and
contains flapper valves which are actuated by the release of
actuator ball 201. The diameter of actuator ball 201 is greater
than the smallest diameter in the drill string and corresponds to
the diameter of the bore of the float equipment. The diameter of
the bore of the float equipment is also greater than the smallest
diameter in the drill string.
[0053] Still referring to FIG. 2, in operation, apparatus in
accordance with one embodiment of the present invention is intended
to be run down a borehole through drilling fluid while in the open
port position. In the "open port position," sleeve 170 of flow
diverter device B (when used), sleeve 171 of wiper plug assembly
WP, and sleeve 172 of drop ball sub DB are positioned such that
drilling fluid may follow flow path FP upward through the bore of
float equipment 160. Following the flow path, drilling fluid then
flows into the housing of drop ball sub DB above actuator ball 201
via aligned housing flow port 167A and sleeve flow port 167B, and
through the bore in the wiper plug. Drilling fluid then fills the
void above the wiper plug fins 163 via the openings between collet
fingers 168. The drilling fluid then flows through drill string S2
and running tool 162, into diverter device B, and finally out of
diverter device B into the annulus between drill string S and the
cemented-in-place casing 205 via aligned flow hole 169A and flow
port 169B. The benefits of surge pressure reduction are thus
provided.
[0054] In the embodiment of the present invention where no diverter
tool is utilized, drilling fluid flows through drill string S2 and
running tool 162 and through drill string S.
[0055] Referring to FIG. 3, once the casing liner has been lowered
to full depth and cementing operations are ready to begin, a drop
ball 200 is dropped down drill string S and into yieldable seat 173
of flow diverter device B. If a diverter tool is not used, the
first landing point for drop ball 200 is yieldable seat 174. The
diameter of drop ball 200 is less than the smallest diameter of any
restriction in drill string S. For example, a 21/4 inch diameter
drop ball may be used for a drill string with inside diameter of 3
inches.
[0056] Referring now to FIG. 4, drilling fluid is pressurized to a
predetermined level above drop ball 200 such that sleeve 170 is
moved axially downward blocking housing flow holes 169A. The flow
diverter device B is now in the "closed port position."
[0057] Referring to FIG. 5, drilling fluid above drop ball 200 is
further pressurized such that the yieldable seat 173 expands, and
drop ball 200 passes through yieldable seat 173 and lands in
yieldable seat 174 of collet finger sleeve 171. Drilling fluid is
then pressurized above drop ball 200 such that sleeve 171 is moved
axially downward which closes the ports formed by the spaces
between collet fingers 168 as illustrated in FIG. 6.
[0058] Referring to FIG. 7, drilling fluid above drop ball 200 is
further pressurized such the yieldable seat 174 expands and drop
ball 200 passes through expanded yieldable seat 174 and lands in
seat 175 of drop ball sub 176. Drilling fluid is then pressurized
to a predetermined level above drop ball 200 such that sleeve 172
is moved axially downward. As sleeve 172 moves downward, the sleeve
engages float valve actuator ball 201 and forces the ball through
yieldable seat 176 as illustrated in FIG. 8.
[0059] With reference to FIG. 9, the float valve actuator ball 201
is released from drop ball sub 166 and moves downward toward the
bottom of casing liner 161 where ball actuates flapper valves of
float equipment 160. Float valve actuator ball 201 then continues
to bottom of casing liner 161 and exits casing liner 161 where it
may subsequently be grinded into filings by downhole drill
equipment.
[0060] With reference to FIG. 10, drilling fluid above drop ball
200 is further pressurized such that yieldable seat 175 is expanded
and drop ball 200 passes through the expanded seat 175, and exits
casing liner where it may subsequently be grinded into filings by
downhole drill equipment. At this time, the cementing operations
are ready to commence.
[0061] With reference to FIG. 11, once cement pumping is complete,
a drill pipe dart 202 is inserted into top of drill string S and
displaced downward by drilling fluid so that dart 202 establishes a
barrier between drilling fluid and cement CE3. With reference to
FIGS. 12 and 14A, once the dart 202 reaches wiper plug assembly WP,
the dart engages a receptacle sleeve 182. The dart 202
conventionally comprises a nose section with a barbed "shark tooth"
profile "c-ring" for connection with receptacle sleeve 182 and
elastomer o-ring seals. The receptacle sleeve 182 comprises a
mating tooth profile for connection with the dart 202 and a seal
bore for receiving the O-rings. In this way, the dart 202 and
receptacle sleeve 182 form a sealed mechanical connection.
[0062] With reference to FIGS. 13 and 14B, a yieldable, disk-shaped
flat washer 181 supports dart receptacle sleeve 182 in the wiper
plug assembly WP. Flat washer 181 is mounted in such a way that
force imparted by dart 202 is carried through the washer 181. As
drilling fluid is further pressured above dart 202, the flat washer
181 yields and deflects slightly downward. The deflection of the
flat washer 181 allows the receptacle sleeve 182 to move slightly
downward. The dart receptacle sleeve 182 serves as a backup to
collet fingers 168 formed on the end of the drill string S2. The
collet fingers 168 are formed such that their lower outer ends
comprise wedge surfaces 179A, which are captured in a mating recess
179B in the top flange portion of the wiper plug assembly WP. As
the dart receptacle sleeve 182 displaces downward due to the
pressure above the dart 202, the radial support for the collet
fingers 168 is lost. The loss of radial support allows the wedge
surfaces 179A to force the collet fingers 168 radially inward
thereby releasing the wiper plug assembly WP from the drill string
S2.
[0063] With reference still to FIG. 13, once released from drill
string S2, the wiper plug WP maybe pumped down the casing liner 161
thereby displacing cement CE3 in the casing liner down through the
flapper valves of float equipment 60. The flapper valves of the
float equipment 160 should prevent any "back-flow" or "u-tube
action" of the cement.
[0064] Once the wiper plug WP has been pumped to the bottom of the
casing liner, the cement is allowed to harden, thereby completing
the hanging and cementing job.
[0065] In another embodiment of the present invention, the drop
ball sub is used to launch an actuator ball without the sliding
sleeve 172 (FIG. 2). Referring to FIG. 18, the drop ball assembly
DB is attached to the bottom of wiper plug assembly WP and
comprises a housing 166 having a set of housing flow holes 167A, an
actuator ball 201, and a yieldable seat 176. The set of housing
flow holes 167A are sized to permit the creation of a pressure
differential between the annular space within the housing 166 and
the space outside the housing when drilling fluid pressure is
increased above the actuator ball 201 to launch the actuator ball
through the yieldable seat 176. In a preferred embodiment, the set
of housing flow holes comprises four holes of 1 inch diameter size
such that the actuator ball may be launched at a pressure
differential of approximately 100 psi. However it is intended that
the holes may be sized to accommodate whatever pressure
differential is required to launch the actuator ball.
[0066] With reference to FIG. 19, once drop ball 200 is used to
move the sleeve 171 axially downward to close the ports formed by
the spaces between collet fingers 168, drilling fluid above drop
ball 200 is further pressurized such that the yieldable seat 174
expands and drop ball 200 passes through expanded yieldable seat
174. The drop ball 200 lands on top of the actuator ball 201 within
the drop ball housing 166 thus creating a clear bore through drill
string S2. Drilling fluid is then pressurized to a predetermined
level above actuator ball 201 such that the actuator ball is forced
through yieldable seat 176 as illustrated in FIG. 20. This is
accomplished by pumping drilling fluid from the drill string into
the drop ball housing 166 at a rate greater than the rate at which
the drilling fluid can exit the housing via the set of flow ports
167A. This creates a pressure differential where the drilling fluid
pressure is greater within the drop ball housing 166 than in the
annular space between the drop ball housing and the casing liner
161. When the drilling fluid pressure differential within the drop
ball housing 166 is increased to a predetermined level, the
yieldable seat yields to launch the actuator ball from the drop
ball housing. In a preferred embodiment, the yieldable seat 176 of
the drop ball housing 166 is fabricated to yield at a pressure
differential of approximately 100 psi.
[0067] With reference to FIG. 20, the float valve actuator ball 201
is released from drop ball sub DB and moves downward toward the
bottom of casing liner 161 where ball actuates the flapper valves
FC2 of float equipment 160 as illustrated in FIG. 10. Float valve
actuator ball 201 and drop ball 200 then continue to bottom of
casing liner 161 and exit casing liner where they may subsequently
be grinded into filings by downhole drill equipment. At this time,
the cementing operations are ready to commence.
[0068] The foregoing has described what may be referred to as a
"two plug system" having one wiper plug and one dart which is used
in the release of the wiper plug. With reference to FIG. 15,
another embodiment of the present invention comprises an upper
liner wiper plug WP1 and a lower liner wiper plug WP2. This type of
system may be referred to as a "four plug system" since it
comprises two wiper plugs and two drill pipe darts to release the
wiper plugs.
[0069] The four plug system of FIG. 15 operates in substantially
the same way as the two plug system. In both the two plug system
and the four plug system, the apparatus is first run down a
borehole until it reaches the required depth to hang a casing
liner. At this depth, a drop ball is pumped down the drill string
into yieldable seat of drop ball sub. Drilling fluid pressure is
increased behind the drop ball to release an actuator ball from the
drop ball sub to activate flapper valves of float collar.
[0070] With reference to FIG. 15, the four plug system comprises an
upper liner wiper plug WP1 attached to drill string DS, a lower
liner wiper plug WP2 attached to the upper liner wiper plug by
release mechanism (see FIG. 16), and a drop ball sub DB attached to
the bottom of the lower liner wiper plug.
[0071] With reference to FIGS. 15 and 17, after the flapper valve
actuator ball 310 is released, a first drill string dart 400 is
pumped down the drill string and into casing liner CL where the
first dart engages a lower liner wiper plug WP2. Drilling fluid
pressure is increased above the first dart 400 so that the lower
liner wiper plug WP2 is released from an upper liner wiper plug WP1
and is pumped downward through the casing liner CL to displace
contaminating drilling mud from the interior of the casing liner.
At the bottom of the casing liner CL, drilling fluid pressure is
further increased above the first dart 400 so that the lower liner
wiper plug latches to the float collar FC. Next, cement is pumped
downward through the casing liner CL and into the annulus between
the borehole and the casing liner. Then, a second drill string dart
(not shown) is pumped down the drill string and into the casing
liner CL where the second dart engages an upper liner wiper plug
WP1. Drilling fluid pressure is increased above the second dart so
that the upper liner wiper plug WP1 is released from the drill
string DS and is pumped downward through the casing liner CL to
displace cement from the interior of the casing liner. At the
bottom of the casing liner CL, drilling fluid pressure is again
increased above the second dart so that the upper liner wiper plug
WP1 latches to the lower liner wiper plug WP2.
[0072] With reference to FIG. 16, the release mechanism for
releasing lower liner wiper plug WP2 from upper liner wiper plug
WP1 comprises lower liner fingers 301 having wedge-shaped ends
301A, upper liner finger receivers 300 having wedge-shaped recesses
300A, a lower liner dart receptacle 302, and a sleeve 303 having
radial protrusions 303A. Initially, the wedge-shaped ends 301A of
lower liner fingers 301 engage the wedge-shaped recesses 300A of
upper liner fingers 300. The protrusions 303A of sleeve 303 prevent
the lower liner fingers 301 from moving radially inward and lock
the wedge shaped-ends 301A in the wedge-shaped recesses 300A. The
sleeve 303 is itself restrained by shear pins 304.
[0073] With reference to FIG. 17, a drill pipe dart 400, having a
diameter less than the diameter of upper liner receptacle 305, is
dropped into the drill string and lands in lower liner dart
receptacle 302. Drilling fluid pressure is increased above dart 400
to shear pins 304 (shown in FIG. 16). Sleeve 303 is now
unrestrained. Drilling fluid pressure is further increased above
dart 400 to push sleeve 303 downward so that protrusions 303A move
below wedge-shaped ends 301A of lower liner fingers 301. The lower
liner fingers 301 are now free to move radially inward to disengage
with wedge-shaped recesses 300A of upper liner fingers 300.
Drilling fluid pressure above dart 400 is increased to pump the
released lower liner wiper plug WP2 downward displacing drilling
mud from the inside walls of the casing liner CL. Once the lower
liner wiper plug WP2 reaches the bottom of the casing liner CL,
drilling fluid pressure is further increased above the dart 400 to
latch the lower liner wiper plug to float collar FC (shown in FIG.
15). Cementing operations may then be commenced.
[0074] With reference to FIG. 15, the upper liner wiper plug WP1
may then be released from the drill string DS by following the same
procedure described above to release wiper plug WP (shown in FIGS.
12, 13, 14A, and 14B) in the two plug system. Once the upper liner
wiper plug WP1 is pumped to the bottom of the casing liner CL and
is latched to the lower liner wiper plug WP2, the cement is allowed
to harden, thereby completing the hanging and cementing job.
[0075] In another embodiment of the four plug system, before the
float equipment is activated, the lower liner wiper plug assembly
is pumped downward such that the drop ball sub engages the float
equipment and then releases the actuator ball to activate the
flapper valves of the float equipment. Referring to FIG. 21, before
the release of the lower liner wiper plug WP2, a drop ball 403 is
dropped from the drill string into the yieldable seat 401 of the
sliding sleeve 402. Drilling fluid is then pressurized to a
predetermined level above drop ball 403 such that sleeve 402 is
moved axially downward blocking the set of housing flow holes 167A.
The drop ball sub DB is now in the "closed port position" (as shown
in FIG. 22). Drilling fluid pressure is increased above the drop
ball 403 such that the seat 401 yields thereby permitting the drop
ball to pass through and land on the actuator ball 201. Cementing
operations can now commence.
[0076] With reference to FIG. 23, after the drop ball sub DB is set
to the closed port position, a first drill string dart 400 is
pumped down the drill string by cement and into casing liner CL
where the first dart engages a lower liner wiper plug WP2. Cement
pressure is increased above the first dart 400 so that the lower
liner wiper plug WP2 is released from an upper liner wiper plug WP1
and is pumped downward through the casing liner CL to displace
contaminating drilling mud from the interior of the casing liner.
At the bottom of the casing liner CL, cement pressure is further
increased above the first dart 400 so that the lower liner wiper
plug latches to the float collar FC.
[0077] Referring to FIG. 24, cement pressure is again increased to
a predetermined level above the first dart 400 to release the first
dart 400 from engagement with the lower liner wiper plug WP2. The
dart 400 lands in the drop ball sub DB near the drop ball 403 and
above the actuator ball 201.
[0078] Referring to FIG. 25, cement pressure is increased to a
predetermined level above the actuator ball 201 to launch the
actuator ball from the drop ball sub DB into the axial bore of the
float collar FC. The actuator ball 201 lands in the seat FC3 of the
actuating sleeve FC1 of the float collar FC.
[0079] Referring to FIG. 26, cement pressure is again increased to
a predetermined level above the actuator ball 201 to displace the
actuating sleeve FC1 from the bore of the float collar FC thus
allowing the flapper valves FC2 of the float collar to activate to
any back-flow of the cement. The upper liner wiper plug is released
and the cementing job is completed as described above.
* * * * *