Plug container with fluid pressure responsive cleanout

A plug container, such as can be used during a cementing operation at an oil or gas well, includes one or more plug holders which seal against a bypass sleeve when the plugs carried in the holders are released to separate columns of fluid pumped into the well. The bypass sleeve is responsive to fluid pressure so that when sufficient fluid pressure is applied to the bypass sleeve, it lifts the plug holder(s) and uncovers one or more cleanout ports in at least one plug holder. The uncovered cleanout port(s) allow residue fluid, such as cement, to flow out of the plug container. The pressurized fluid can be applied through a hose connected to a single structural member of the plug container so that the hose does not need to be disconnected when the remainder of the plug container is being assembled or disassembled.

BACKGROUND OF THE INVENTION 
This invention relates to a plug container used in the introduction and 
separation of fluids in a well, such as the introduction and separation of 
cement slurry and displacing fluid in an oil or gas well. The plug 
container permits residue fluid, such as cement, to be cleaned from the 
plug container in response to a pressurized fluid lifting a bypass member 
and one or more plug holders disposed in the plug container. 
Cement is used in oil or gas wells for various purposes. One purpose is to 
secure a tubular string (e.g., a casing or a liner) in the well bore. This 
is typically done by pumping cement down the tubular string and forcing it 
back up an annular space between the outside of the string and the well 
bore or a larger diameter string in which the first-mentioned string is 
disposed. To separate the cement slurry from drilling mud typically in the 
well when the cementing operation begins, a bottom cementing plug is 
placed in line and pumped down the string by the force of the following 
cement slurry. This bottom plug serves to minimize contamination of the 
cement as it is being pumped down the tubular string. It also wipes any 
accumulated mud film from the inner diameter of the string and pushes it 
ahead. To separate a following displacing fluid used to push the cement 
slurry out the tubular string and up the annular space, a top cementing 
plug is placed in line and pushed down the string by the displacing fluid. 
This top plug follows the cement and wipes any accumulated cement film 
from the inner diameter of the tubular string. It also prevents or reduces 
any contamination of the cement by the displacing fluid. 
In wells drilled on land, surface-mounted plug containers are used in many 
cementing jobs to release the cementing plugs at the proper time. Normal 
job operations will have the bottom cementing plug loaded into the plug 
container prior to pumping cement. The top cementing plug will typically 
be loaded after the bottom plug is released. If well conditions dictate, 
two plug containers or a double plug container may be used to release both 
cementing plugs when desired without opening the plug container. 
Subsea (ocean floor) completions are different from the aforementioned 
land-based cementing operations in that the cementing plugs used for 
separating the fluids are preferably located in the tubular string below 
the ocean floor. This is preferred because these plugs have a diameter 
large enough to wipe the inner diameter of the tubular string extending 
below the ocean floor, and this tubular string (and thus each plug) 
typically has a larger diameter than need be used for connecting this 
string with the equipment on the rig at the ocean's surface. Thus, the 
cement slurry is preferably pumped from the surface through a string of 
drill pipe smaller than the string being cemented, which smaller string 
extends between the surface rig and the downhole string to be cemented. 
This creates the need for a second type of plug container that houses 
elements, which may broadly be called "plugs" also, which are of smaller 
diameter to permit these plugs to pass through the narrower connecting 
string and into the downhole cementing plugs. A system using this 
technique is the Halliburton Energy Services' sub-surface release system 
("SSR Cementing Plug Method"). This system provides a means of wiping 
different pipe sizes; therefore, smaller diameter drill pipe can be used 
as described instead of the larger diameter casing that otherwise would be 
run between the rig floor and the ocean floor. 
This prior art system will be briefly explained with reference to FIGS. 
1-3. These drawings schematically illustrate the sequence of operation. 
FIG. 1 shows bottom and top cementing plugs 2, 4, respectively, installed 
at the top of casing 6 (i.e., the tubular string in the well bore) prior 
to beginning the actual cementing operation. A set of releasing pins 
attaches the bottom cementing plug 2 to the top cementing plug 4. 
A weighted plastic or bronze ball 8 housed in a surface plug container 10 
is dropped through connecting drill pipe 12 ahead of the cement slurry. 
The ball 8 passes through a wider axial channel of the top plug 4 and 
lands on a seat of the bottom plug 2. A differential pressure applied 
through the drill pipe 12 from the surface separates the thus sealed 
bottom plug 2 from the top plug 4. 
FIG. 2 illustrates how the bottom plug 2 has been discharged from the top 
plug 4 and seated on a float collar 14 (or float shoe). At this point, a 
small increase in pressure exposes port holes in the plug 2 so that the 
cement slurry can be pumped around the bottom plug releasing ball 8. 
A double collet releasing mechanism holds the top plug 4 in place and 
permits circulation through the top cementing plug 4 at normal 
displacement rates prior to release of the top plug 4. To release the top 
cementing plug 4, a top releasing plug 16 from the surface plug container 
10 is pumped down the drill pipe 12 behind the slurry and into the top 
cementing plug 4 where it latches and seals therewith. An applied pressure 
shears releasing pins to enable the top plug 4 to move down the casing 6. 
As shown in FIG. 3, the top cementing plug 4 lands on the bottom cementing 
plug 2 to shut off flow in conventional manner. 
Another relevant prior system is schematically illustrated in FIG. 4. This 
represents the Halliburton Energy Services' selective release system ("SR 
Plug System"). This system makes it possible to perform a multiple stage 
cementing job on ocean floor completions or conventional land liner jobs 
using a Halliburton Multiple Stage Cementer and three plugs. 
The SR Plug System comprises a first stage top plug 18, an opening plug 20, 
and a closing plug 22, all of which are located downhole as in the SSR 
Cementing Plug Method. These are respectively released by suitable drill 
pipe plugs initially contained in a surface/rig floor located plug 
container 24. The system is called selective release because it is 
designed so that the upper downhole plugs cannot be released until after 
the lower downhole plugs are released. 
It is to the SSR Cementing Plug Method and the SR Plug System that the 
present invention is particularly directed. More specifically, the present 
invention is directed to the surface plug containers 10, 24. Although the 
foregoing systems have been successfully used, the surface plug containers 
10, 24 have been of the manifold type as shown by manifold 26 in FIGS. 1-3 
and manifold 28 in FIG. 4. Such manifolds have shortcomings. For example, 
if a fluid line is connected to a manifold, the manifold cannot be 
rotated. Valves are required in a manifold to direct fluid flow; these add 
weight, expense and maintenance to the plug container, and additional 
pressure lines are needed to operate the valves remotely. A manifold 
restricts flow area, and a manifold can cause the plug container to tilt 
off-center, making it harder to stab into casing or drill pipe. 
Accordingly, there is the need for an improved plug container that can be 
used without the manifolds 26, 28 to overcome the aforementioned 
shortcomings. 
SUMMARY OF THE INVENTION 
The present invention overcomes the above-noted and other shortcomings of 
the prior art by providing a novel and improved plug container with fluid 
pressure responsive cleanout. Advantageous features of this invention 
include a simpler design, less maintenance, less weight, shorter swing 
radius, larger flow area and less expensive than at least some other types 
of plug containers. Two specifically significant features of the present 
invention are its fluid pressure responsive cleanout and its single body 
hose connection for conducting the pressurized fluid to the locus of 
application. The former enables remote control of the cleanout process, 
and the latter reduces the chance for error is assembling the plug 
container. 
The plug container of the present invention broadly comprises a housing. 
Disposed in the housing is a plug holder. The plug holder is releasably 
disposed in the housing so that in response to being released the plug 
holder moves from a first location within the housing, wherein fluid flow 
along an outside of the plug holder is permitted, to a second location 
within the housing, wherein fluid flow along the outside of the plug 
holder is blocked. The plug container further comprises fluid pressure 
responsive means, responsive to fluid pressure communicated into the 
housing, for moving the plug holder from the second location to permit 
fluid flow along the outside of the plug holder. 
The plug container can be defined more specifically as comprising: a 
housing; a bypass sleeve slidably disposed within the housing at a bottom 
end thereof so that the bypass sleeve is movable within the housing 
between a lower position and an upper position; a plug retaining sleeve 
disposed within the housing, the plug retaining sleeve having a radial 
opening defined at a lower end thereof; a plug release plunger connected 
to the housing for holding the plug retaining sleeve at a spaced location 
above the bypass sleeve and for releasing the plug retaining sleeve 
therefrom so that the plug retaining sleeve drops and engages the bypass 
sleeve with the radial opening of the plug retaining sleeve blocked by the 
housing in response to the bypass sleeve in the lower position; and means 
for communicating a fluid to the bypass sleeve, wherein the fluid is 
pressurized for moving the bypass sleeve, and the plug retaining sleeve 
when engaged therewith, upwardly to the upper position within the housing 
so that the radial opening of the plug retaining sleeve is unblocked, 
whereby fluid flow along and through the plug retaining sleeve is 
permitted in response to the pressurized fluid communicated to the bypass 
sleeve. 
In a particular implementation, the housing includes an upper mandrel, a 
single member main body connected to the upper mandrel, and a lower 
mandrel connected to the main body. In this implementation, the means for 
communicating a fluid includes a hose connected only to the single member 
main body so that the hose can remain connected during assembly and 
disassembly of the main body relative to the upper mandrel and the lower 
mandrel. 
The present invention provides a related method, specifically a method of 
establishing fluid flow in a plug container. This method comprises 
releasing a plug holder in a housing so that the plug holder moves 
downward in the housing into engagement adjacent a bypass sleeve disposed 
in the housing, wherein the plug holder has an opening defined therein and 
wherein the opening is blocked to fluid flow therethrough in response to 
the engagement adjacent the bypass sleeve when the bypass sleeve is in a 
lower position. The method further comprises flowing pressurized air into 
the housing and against the bypass sleeve to pneumatically lift the bypass 
sleeve and the released plug holder to a position wherein the opening 
defined through the plug holder is unblocked to fluid flow within the 
housing. Flowing pressurized air of the preferred embodiment includes 
communicating the air from a pressurized source, through a swivel, into 
the housing, through a hose connected to a single member of the housing, 
and back into the housing and against the bypass sleeve. 
Therefore, from the foregoing, it is a general object of the present 
invention to provide a novel and improved plug container with fluid 
pressure responsive cleanout. Other and further objects, features and 
advantages of the present invention will be readily apparent to those 
skilled in the art when the following description of the preferred 
embodiment is read in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
The preferred embodiment plug container 100 of the present invention can be 
used in place of the plug container 10 or 24 shown in FIGS. 1-4. The 
structure of the preferred embodiment plug container 100 will be described 
with reference to FIGS. 5 and 6. The operation will be described with 
reference also to FIGS. 7 and 8. 
The plug container 100 includes an upper adapter 102 (FIG. 5A) having a 
hollow interior through which a primary fluid (e.g., cement slurry, 
displacing fluid, etc.) can flow. The upper end of the hollow interior is 
threaded to couple with a top drive unit (not shown) of a type known in 
the art. The lower end of the upper adapter 102 is externally threaded for 
coupling with a rotatable portion 104 of a swivel assembly 106 (FIG. 5A). 
The rotatable portion 104 is a cylindrical mandrel which has an axial 
opening 105 through which the primary fluid can flow. The rotatable 
portion 104 has radial openings 108 which communicate the axial opening 
105 with hose connector ports 110 forming part of a stationary portion 112 
of the swivel assembly 106. The rotatable portion 104 is journaled in the 
stationary portion 112 by upper and lower bearings 114 so that the 
rotatable portion 104 can rotate within the stationary portion 112. 
The hose connector ports 110 provide for a cement slurry or a displacing 
fluid or a clean out fluid to be injected into the plug container 100 via 
the swivel assembly 106. 
The stationary portion 112 of the swivel assembly 106 also has means for 
connecting to a source of pressurized fluid. This connecting means 
includes one or more ports 116. In the preferred embodiment, the source of 
pressurized fluid is air so that the ports 116 connect with pneumatic 
hoses. 
The stationary portion 112 of the swivel assembly 106 allows the fluid 
ports 110, 116 and connecting lines to remain stationary when fluid is 
pumped and the plug container 100 is rotated. The swivel assembly 106 also 
allows pneumatic pressure to be applied to subsequently described plug 
release plungers and a bypass sleeve of the plug container 100 even when 
the plug container 100 is rotated. 
Rotation of the plug container 100 can occur because the remainder of it is 
connected to an external thread at a lower end of the rotatable portion 
104 of the swivel assembly 106. This connected portion of the plug 
container 100 includes a housing 120. More particularly, an upper mandrel 
122 (FIG. 5A) of the housing 120 is connected to the rotatable portion 
104. The upper mandrel 122 has an axial channel through which the primary 
fluid flows. This flow is diverted through lower ports 124 defined at the 
bottom of the upper mandrel 122. 
The upper mandrel 122 also has longitudinal channels 126 defined therein. 
These communicate with one or more of the ports 116 of the swivel assembly 
106. The channels 126 communicate at their respective upper ends with the 
ports 116. The lower ends of the channels 126 communicate with radial 
ports 128 defined in the upper mandrel 122. The radial ports 128 also 
communicate with radial ports 130 defined in the top end of a single 
member main body 132 (FIGS. 5A and 5B) of the housing 120. The ports 128, 
130 communicate when the main body 132 is threaded on the lower end of the 
upper mandrel 122. 
Referring to FIG. 5B, the main body 132 is cylindrical, as are the other 
body portions described hereinabove. The main body 132 also has an axial 
hollow interior defining a cylindrical plug holder receiving chamber 134. 
The bottom end of this chamber 134 communicates with a lower mandrel 136 
(FIG. 5B) of the housing 120 as the lower mandrel 136 is threadedly 
connected to the bottom end of the main body 132. Radial passages 138 are 
defined in the wall of the lower mandrel 136. These passages or ports 138 
communicate with radial ports 140 defined through the wall at the bottom 
end of the main body 132. The radial ports 138 open within the interior of 
the lower mandrel 136 through a cylindrical inner surface 142. 
The surface 142 terminates at its lower end at a threaded coupling that 
receives and connects with a lower adapter 144. The other end of the 
surface 142 terminates at a radially inwardly extending annular surface 
146. The opposite edge of the surface 146 intersects a cylindrical surface 
148 in which seal members 150 are disposed. The surface 148 transitions 
into the upper mouth of the axial channel defined through the lower 
mandrel 136. The surface 148 opens into radial ports 156 through which 
grease or other suitable lubricant can be injected. 
The lower mandrel 136 also has radial lubrication ports 158 defined between 
the ports 138 and the lower end of the lower mandrel 136. 
Referring to FIG. 5C, the lower adapter 144 connected to the lower mandrel 
136 houses any suitable plug indicator device for detecting the passage of 
plugs from the plug container 100. This device includes a conventional 
mechanical arm 160 in FIG. 5C. The lower end of the lower adapter 144 has 
a threaded pin end to connect to the drill string 12 when the present 
invention is used with the systems of FIGS. 1-4. The lower adapter 144 has 
a hollow interior extending axially therethrough in communication with the 
axially aligned hollow interiors of the previously described body members. 
The plug container 100 further comprises one or more plug holders 
releasably mounted within the chamber 134 of the main body 132 of the 
housing 120. Two such plug holders are shown in FIG. 5B. One is defined by 
a lower plug retaining sleeve 166 and the other is defined by an upper 
plug retaining sleeve 168. Each of these is spaced from the inner surface 
of the main body 132 by respective spacer members 170, 172 welded to the 
outer surfaces of the plug retaining sleeves 166, 168. 
The lower plug retaining sleeve 166 has a bottom edge 174 from which an 
annular beveled surface 176 extends. An outer cylindrical surface 178 
extends from the surface 176. A shoulder 180 extends radially outward from 
the surface 178 and an upper cylindrical surface 182. The surface 182 
terminates at an upper rim 184 having an internal annular beveled surface 
186. 
Extending from the inner edge of the surface 186 is a cylindrical surface 
188. The surface 188 defines an interior region of the sleeve 166 wherein 
a plug, specifically a releasing dart 190, is received. 
From the lower end of the surface 188, a surface 192 tapers inwardly to a 
cylindrical surface 194. One or more openings 196 are defined radially 
between the surfaces 194, 178. At least one opening 198 is similarly 
defined. The opening 198 receives the plunger from a plug release plunger 
200 and one of the openings 196 receives the plunger of a plug release 
plunger 202 as more clearly shown in FIG. 6. The plunger 200 supports a 
sealing ball 204 shown in FIGS. 5B and 6. The plug release plunger 202 
supports the dart 190. 
The upper plug retaining sleeve 168 is similar to the lower sleeve 166; 
however, as shown in FIG. 5B, the lower tip portion is shorter in that it 
does not have the outer cylindrical surface 178 and the inner cylindrical 
surface 194. The upper sleeve 168 receives a releasing dart 206. In a 
specific implementation, the dart 206 has a rubber wiper body with the 
same outer diameter as the rubber wiper body of the dart 190, but the dart 
206 has an aluminum nose with a greater outer diameter than the aluminum 
nose of the dart 190; thus, the dart 190 can pass through a downhole plug 
or other object sized to receive and stop the larger nose of the dart 206. 
Both the sleeve 168 and the dart 206 are releasably supported by a plug 
release plunger 208. 
A cylindrical cap 210 (FIG.5B) is connected to the upper mandrel 122 (FIG. 
5A). When the upper sleeve 168 is on the plug release plunger 208, the top 
end of the upper sleeve 168 is received in a cavity of the cap 210 and 
flow of primary fluid through the chamber 134 goes around the outside of 
the upper sleeve 168. 
The plug container 100 still further comprises fluid pressure responsive 
means for moving the one or more plug holders from lower, released 
positions or locations, to be subsequently described, to permit fluid flow 
along the outside of the plug holder(s) after they have been released. 
This means is implemented in the preferred embodiment by a bypass sleeve 
222 (FIG. 5B). The bypass sleeve 222 is a cylindrical member having 
opposing annular surfaces 224, 226 extending from the main exterior 
surface of the bypass sleeve 222. Cylindrical surfaces 228, 230 extend 
towards each other from the respective surfaces 224, 226. An annular 
surface 232 extends radially outward from the surface 228, and an annular 
surface 234 extends radially outward from the surface 230. A cylindrical 
surface 236 extends between the annular surfaces 232, 234. A sealing 
member 238 is received in a groove defined in the surface 236. 
The upper portion of the bypass sleeve 222 is sealingly received by the 
seals 150 and lubricated via the ports 156. The lower portion of the 
bypass sleeve 222 is received by seals 240 disposed in the upper end of 
the lower adapter 144, and the lower portion is lubricated via the ports 
158. The bypass sleeve 222 is movable within these sealed relationships 
between a lower position shown in FIG. 5B wherein the surface 224 abuts an 
upper annular surface 242 of the lower adapter 144. In its uppermost 
position shown in FIG. 8, the annular surface 226 abuts the annular 
surface 146 of the lower mandrel 136. This movement occurs in response to 
pressure applied through one of the passages 138 as further described 
below. 
The plug container 100 also comprises means for communicating a fluid to 
the bypass sleeve 222. This means is defined in the preferred embodiment 
by one or more of the longitudinal channels 126 of the upper mandrel 122 
(FIG. 5A). This means is further defined by one or more hoses 244 
connected between the ports 130, 140 of the main body 132 (FIGS. 5A and 
5B). This means is still further defined by the radial passages 138 
defined in the lower mandrel 136 (FIG. 5B). It is through the flow path 
established by these elements and the associated ports that pressurized 
fluid, specifically air, from a source connected to the ports 116 (FIG. 
5A) of the stationary portion 112 of the swivel assembly 106 is applied to 
either the surface 232 or the surface 234 of the bypass sleeve 222 (FIG. 
5B) whereby the bypass sleeve 222 is moved between its upper and lower 
positions, respectively. 
Of the aforementioned fluid communicating means, it is a particular 
advantage of the present invention that the pneumatic hose(s) 244 are 
connected only to the single member main body 132. Thus, the hose(s) 244 
do not need to be disconnected, and possibly misplaced or improperly 
reconnected, during assembly or disassembly of the remainder of the plug 
container 100. 
During operation, the plug container 100 is made up on a top drive unit. 
Drill pipe, such as 12 in FIGS. 1-4, is made up on the bottom of the plug 
container 100. Fluid lines and pneumatic hoses are connected at 110, 116, 
respectively, of the swivel assembly 106 shown in FIG. 5A. The pneumatic 
lines connected to the ports 116 control both the plug release plungers 
200, 202,208 and the bypass sleeve 222. This control can be effected 
remotely from the plug container 100 so that a person need not be 
physically adjacent the plug container 100 to obtain the following 
operation, which clearly provides a safety advantage over plug containers 
which are manually or otherwise locally operated adjacent the plug 
container. 
FIG. 5B shows the position of the respective elements of the plug container 
100 in a "loaded" or a "ready-to-use" configuration. That is, the plug 
container 100 is loaded with the ball 204 and the releasing darts 190, 206 
and these elements are held by their respective plug release plungers. 
When the ball 204 is to be released to seal in a lower downhole plug such 
as shown in the configurations of FIGS. 1-4, the plug release plunger 200 
is retracted in known manner under pneumatic control through a selected 
one or more of the ports 116 of the swivel assembly 106, whereby the ball 
204 drops through the axial opening defined through the plug container 100 
and travels downhole for sealing with a lower downhole cementing plug in 
known manner as referred to above. 
When the lower dart 190 is to be released to engage the next downhole 
cementing plug, the plug release plunger 202 is retracted. This releases 
both the sleeve 166 and the dart 190. In response to cement (for example) 
being pumped behind the dart 190, it is carried down and out of the plug 
container 100 into the lower structure in the well. The sleeve 166, 
however, stops when it engages the bypass sleeve 222 and/or the lower 
mandrel 136. A similar reaction occurs when the plug release plunger 208 
is retracted. The upper sleeve 168 drops into engagement with the lower 
sleeve 166 and the releasing dart 206 is pumped out of the plug container 
100 for use downhole in a known manner. The lower sleeve 166 has the 
external shoulder 180 which, when the lower sleeve 166 drops, seals 
against the top end of the lower mandrel 136. The upper sleeve 168 has a 
taper on the bottom end which, when the upper sleeve 168 drops, seals 
against the top end of the lower sleeve 166. The configuration of the 
relevant portion of the plug container 100 resulting from these actions is 
shown in FIG. 7. 
In the configuration of FIG. 7, it is to be noted that the radial ports 196 
defined through the lower end of the lower sleeve 166 are blocked to fluid 
flow since they are adjacent an inner surface of the lower mandrel 136 and 
the shoulder 180 of the lower sleeve 166 seals with the top of the lower 
mandrel 136. Thus, it will be apparent that cement or other fluid which 
has been pumped through the plug container 100 will fill an annulus 246 of 
the chamber 134 as shown in FIG. 7. If this is cement, it can harden if it 
is not cleaned out. 
To enable such clean-out to occur, the present invention incorporates the 
pressure responsive means implemented by the bypass sleeve 222. With the 
plug container 100 in the configuration shown in FIG. 7, pressurized fluid 
is applied through the ports 116 of the swivel assembly 106. In the 
preferred embodiment, this fluid source is pressurized air. This 
pressurized air is communicated through at least one channel 126 of the 
upper mandrel 122, at least one pneumatic hose 244 connected to at least 
one lower passage 138 (specifically port 138a in FIG. 7) of the lower 
mandrel 136 so that pressure is applied to the surface 232 of the bypass 
sleeve 222. The upper passage 138b (FIG. 7) defined through the lower 
mandrel 136 is vented to atmosphere (or other environment having lower 
pressure than is applied to the surface 232) through the respective fluid 
conducting means of which it is a part. In response to the resultant 
pressure differential (e.g., a nominal 100 psi pressure differential), the 
bypass sleeve 222 moves upwardly, lifting the sleeves 166, 168. This moves 
the top of the upper sleeve 168 back into the cap 210 and it moves the 
radial ports 196 up so that they are again uncovered. Fluid is then 
directed around the outside of the sleeves 166, 168 and through the ports 
196 at the bottom of the lower sleeve 168, cleaning out the annular space 
246 and preventing cement from setting up therein. 
Thus, the present invention is well adapted to carry out the objects and 
attain the ends and advantages mentioned above as well as those inherent 
therein. While a preferred embodiment of the invention has been described 
for the purpose of this disclosure, changes in the construction and 
arrangement of parts and the performance of steps can be made by those 
skilled in the art, which changes are encompassed within the spirit of 
this invention as defined by the appended claims.