U.S. patent application number 12/766780 was filed with the patent office on 2011-02-24 for wellbore circulation assembly.
Invention is credited to Rudolph Ernst Krueger, V, Philip Mock, Eric O'Neal.
Application Number | 20110042100 12/766780 |
Document ID | / |
Family ID | 42752865 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110042100 |
Kind Code |
A1 |
O'Neal; Eric ; et
al. |
February 24, 2011 |
WELLBORE CIRCULATION ASSEMBLY
Abstract
In some embodiments, a circulation assembly can direct all or
substantially all fluid downstream in a drill string in a first
mode of operation, and some or all fluid to an annulus in a second
mode. Operation of the circulation assembly can be repeatedly
changed between the modes of operation. In some embodiments, the
circulation assembly can comprise other modes wherein fluid is
apportioned between the annulus and the downstream drill
string.
Inventors: |
O'Neal; Eric; (Mission
Viejo, CA) ; Krueger, V; Rudolph Ernst; (Aliso Viejo,
CA) ; Mock; Philip; (Costa Mesa, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
42752865 |
Appl. No.: |
12/766780 |
Filed: |
April 23, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61234935 |
Aug 18, 2009 |
|
|
|
61236053 |
Aug 21, 2009 |
|
|
|
Current U.S.
Class: |
166/373 ;
166/316 |
Current CPC
Class: |
E21B 21/103
20130101 |
Class at
Publication: |
166/373 ;
166/316 |
International
Class: |
E21B 34/06 20060101
E21B034/06; E21B 34/00 20060101 E21B034/00 |
Claims
1. A flow management assembly for selectable direction of working
fluid in an hydraulic system for well operation, the assembly
comprising: a fluid inlet at an upstream end of the assembly
configured to receive fluid from an upstream component of the
system; a first fluid outlet at a downstream end of the assembly
configured to deliver fluid to downstream component of the system;
a first passage connecting the fluid inlet to the first fluid
outlet; a second fluid outlet configured to discharge fluid from
the system; a second passage connecting the fluid inlet to the
second fluid outlet; a valve movable repeatedly between a first
configuration wherein discharge of fluid from the system through
the second fluid outlet is inhibited and a second configuration
wherein the discharge of fluid from the system through the second
fluid outlet is greater than in the first configuration.
2. The assembly of claim 1, wherein the discharge of fluid through
the second passage is substantially prevented when said valve is in
the first configuration.
3. The assembly of claim 1, wherein the valve comprises a spring
that biases the valve to the closed configuration.
4. The assembly of claim 1, wherein the valve is operable at least
partially in response to upstream pressure of the working
fluid.
5. The assembly of claim 1, wherein the valve is operable in a
first mode wherein the valve is responsive to increase of upstream
pressure to move the valve to the open configuration, and a second
mode wherein the valve is not responsive to increase of upstream
pressure to move the valve to the open configuration.
6. The assembly of claim 5, wherein the valve comprises an index to
switch the operation of the valve between the first mode and the
second mode.
7. The assembly of claim 1, further comprising a pressure
compensated chamber operatively connected to the valve.
8. The assembly of claim 1, wherein said valve is operable from
outside of the wellbore when the assembly is positioned within the
wellbore.
9. The assembly of claim 1, wherein said valve is changeable from
said first configuration to said second configuration in response
to pressure changes.
10. The assembly of claim 1, wherein said valve is positioned at
least partially within said second passage.
11. The assembly of claim 1, wherein delivery of fluid to the
downstream component through the first fluid outlet is inhibited in
the second configuration.
12. The assembly of claim 11, wherein delivery of fluid to the
downstream component through the first fluid outlet is
substantially prevented in the second configuration.
13. A method for directing fluid flow within an hydraulic system
for operation in a wellbore, comprising: receiving fluid from an
upstream component of the system; directing the fluid toward a
downstream component of the system; opening a passage to discharge
at least a portion of the fluid from the system; closing the
passage to direct all of the fluid toward the downstream
component.
14. The method of claim 13, wherein the passage is opened in
response to an increase in upstream pressure of the fluid.
15. The method of claim 14, wherein the passage is closed in
response to a decrease in the upstream pressure of the fluid.
16. The method of claim 15, wherein after the passage has been
opened, the passage is reopened in response to an increase of
upstream pressure only after a series of upstream pressure changes
comprising an increase in the upstream pressure, and a subsequent
decrease in the upstream pressure.
17. The method of claim 13, further comprising reopening the
passage.
18. The method of claim 13, further comprising adjusting a value of
the upstream pressure at which the passage is opened based at least
partially on a pressure exterior to the system.
19. The method of claim 13, wherein the hydraulic system comprises
one of coiled tubing, jointed tubing, and drill pipe
20. The method of claim 13, wherein fluid is directed toward the
downstream component of the system, which comprises one of a
tractor, a nozzle sub, an anti-stall tool, a logging tool, a
perforation gun, a sand washing tool, a measurement-while-drilling
tool, a logging-while-drilling tool, a downhole motor, a drill bit,
a milling bit, a steering assembly, and a special actuation
tool.
21. A downhole assembly, comprising: a coiled tubing drill string;
a circulation assembly comprising an upstream connector, a
downstream connector, a first passage between the upstream
connector and the downstream connector, a second passage between
the upstream connector and an exterior of the system, a valve
communicating with the second passage, an index mechanism
configured to operate in cooperation with the valve; and at least
one of a tractor and a bottom hole assembly.
22. The downhole assembly of claim 21, wherein the circulation
assembly further comprises a flow divider at an intersection of the
first passage and the second passage.
23. The downhole assembly of claim 21, wherein the circulation
assembly further comprises a pressure compensated chamber
configured to apply pressure to the valve in opposition to pressure
asserted on the valve by fluid within the second passage.
24. The downhole assembly of claim 23, wherein the index mechanism
is positioned between the valve and the pressure compensated
chamber.
25. The downhole assembly of claim 21, wherein the bottom hole
assembly comprises at least one of a nozzle sub, a logging tool, a
perforation gun, a sand washing tool, a drilling tool, a motor, a
drill bit, and a milling bit.
26. The downhole assembly of claim 21, comprising a tractor, the
tractor being directly connected to the circulation assembly.
27. The downhole assembly of claim 21, comprising a tractor, the
tractor being spaced from the circulation assembly.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119 of U.S. Provisional Patent Application Ser. No.
61/234,935, entitled "WELLBORE CIRCULATION ASSEMBLY," filed on Aug.
18, 2009; and U.S. Provisional Patent Application Ser. No.
61/236,053, entitled "WELLBORE CIRCULATION ASSEMBLY," filed on Aug.
21, 2009. Each of the above-identified applications is hereby
incorporated by reference in its entirety.
FIELD OF THE DISCLOSURE
[0002] The present invention generally relates to control of fluid
flow in downhole systems and, in some embodiments, to methods and
assemblies for controlling the flow of fluid within coiled tubing
systems in particular.
BACKGROUND OF THE DISCLOSURE
[0003] Downhole operations routinely encounter pump rate
limitations due to surface pressures exceeding the capacity of the
pumps or the tubing. High surface pressures can be attributed to a
variety of sources such as fluid weight, frictional loss, and pump
rate. This problem is exacerbated when the downhole tools being
used create additional back pressure or have rate limitations.
These tools can include, for example, positive displacement motors
(PDM), hydraulic tractors, and multi-lateral entry tools (MLT).
SUMMARY OF THE DISCLOSURE
[0004] In some embodiments, a circulation assembly can direct all
or substantially all fluid downstream in a drill string in a first
mode of operation, and some or all fluid to an annulus in a second
mode. Operation of the circulation assembly can be repeatedly
changed between the modes of operation. In some embodiments, the
circulation assembly can comprise other modes wherein fluid is
apportioned between the annulus and the downstream drill string.
The circulation assembly can be an independent subassembly of a
drill string, or form a part of equipment that also performs other
functions.
[0005] In one embodiment, a flow management assembly for selectable
direction of working fluid in an hydraulic system for well
operation can comprises a fluid inlet, a first fluid outlet, a
first passage, a second fluid outlet, a second passage, and a
valve. The fluid inlet is positioned at an upstream end of the
assembly and configured to receive fluid from an upstream component
of the system. The first fluid outlet is positioned at a downstream
end of the assembly and configured to deliver fluid to downstream
component of the system. The first passage connects the fluid inlet
to the first fluid outlet. The second fluid outlet is configured to
discharge fluid from the system. The second passage connects the
fluid inlet to the second fluid outlet. The valve is movable
repeatedly between a first configuration and a second
configuration. In the first configuration, discharge of fluid from
the system through the second fluid outlet is inhibited. In the
second configuration, the discharge of fluid from the system
through the second fluid outlet is greater than in the first
configuration.
[0006] In one embodiment, a method for directing fluid flow within
an hydraulic system for operation in a wellbore comprises the steps
of receiving fluid from an upstream component of the system,
directing the fluid toward a downstream component of the system,
opening a passage to discharge at least a portion of the fluid from
the system, and closing the passage to direct all of the fluid
toward the downstream component.
[0007] In one embodiment, a downhole assembly comprises a coiled
tubing drill string, a circulation assembly, and at least one of a
tractor and a bottom hole assembly. The circulation assembly
comprises an upstream connector, a downstream connector, a first
passage, a second passage, a valve and an index mechanism. The
first passage extends between the upstream connector and the
downstream connector. The second passage extends between the
upstream connector and an exterior of the system. The valve
communicates with the second passage. The index mechanism is
configured to operate in cooperation with the valve.
[0008] All of these embodiments are intended to be within the scope
of the invention herein disclosed. These and other embodiments of
the present invention will become readily apparent to those skilled
in the art from the following detailed description of the preferred
embodiments having reference to the attached figures, the invention
not being limited to any particular preferred embodiment(s)
disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic diagram of the major components of a
coiled tubing drilling system having gripper assemblies.
[0010] FIG. 2 is a schematic diagram illustrating the operation of
a circulation assembly according to an embodiment.
[0011] FIG. 3 is a cross-sectional plan view of a circulation
assembly according to an embodiment.
[0012] FIG. 4 is an enlarged view of portion IV-IV, shown in FIG.
3.
[0013] FIG. 5 is a schematic diagram illustrating the operation of
a circulation assembly according to an embodiment.
[0014] FIG. 6 is a schematic diagram illustrating the operation of
a circulation assembly according to an embodiment.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0015] FIG. 1 shows a coiled tubing system 20 for use within a
passage. The coiled tubing drilling system 20 may include a power
supply 22, tubing reel 24, tubing guide 26, tubing injector 28, and
coiled tubing 30, all of which are well known in the art. The
system 20 can be used in conjunction with various other types of
equipment, for example, one or more tractors 50 and a bottom hole
assembly 32. The coiled tubing 30 and downhole equipment form a
drill string. The coiled tubing system can be used with a
circulation assembly 100 that directs flow received from upstream
in the drill string to one or both of downstream equipment and an
annulus 40, which is defined by the space between the drill string
and an inner surface 42 of the passage. Although specific
embodiments are herein described in the context of coiled tubing
systems, embodiments can be used with other types of drill strings,
including jointed tubing and drill pipe.
[0016] With continued references to FIG. 1, the system 20 can be
used with at least one downhole tractor 50 for moving the system
20. In some embodiments, multiple tractors can be connected
end-to-end may allow the use of smaller tractors, thereby
facilitating maneuvering the coiled tubing system through a passage
with relatively small radius turns. Although two downhole tractors
50 connected end-to-end are preferred in some applications, those
of skill in the art will understand that a single tractor 50, or
more than two tractors 50 could be used.
[0017] The tractor 50 can have one or more gripper assemblies in
some embodiments. Those of skill in the art will understand that
any number of gripper assemblies may be used. Various embodiments
of the gripper assemblies are shown and described in U.S. Pat. No.
6,464,003, filed on Feb. 6, 2001, entitled "GRIPPER ASSEMBLY FOR
DOWNHOLE TRACTORS;" U.S. Pat. No. 6,715,559, filed on Dec. 3, 2001,
entitled "GRIPPER ASSEMBLY FOR DOWNHOLE TRACTORS;" U.S. Pat. No.
7,392,859, filed on Mar. 17, 2005, entitled "ROLLER LINK TOGGLE
GRIPPER AND DOWNHOLE TRACTOR;" U.S. Patent Application Publication
No. 2007-0209806, filed on Mar. 8, 2007, entitled "EXPANDABLE RAMP
GRIPPER;" U.S. Patent Application Publication No. 2008-0149339,
filed on Nov. 13, 2007, entitled "VARIABLE LINKAGE ASSISTED
GRIPPER;" all of which are hereby incorporated herein by reference,
in their entirety.
[0018] It should be noted that gripper assemblies may be used with
a variety of different tractor designs, including, for example, (1)
the "PULLER-THRUSTER DOWNHOLE TOOL," shown and described in U.S.
Pat. No. 6,003,606 to Moore et al.; (2) the "ELECTRICALLY SEQUENCED
TRACTOR," shown and described in U.S. Pat. No. 6,347,674 to Bloom
et al.; (3) the "ELECTRO-HYDRAULICALLY CONTROLLED TRACTOR," shown
and described in U.S. Pat. No. 6,241,031 to Beaufort et al.; (4)
the intervention tractor or "TRACTOR WITH IMPROVED VALVE SYSTEM"
shown and described in U.S. Pat. No. 6,679,341 to Bloom et al and
U.S. Pat. No. 7,121,364, all of which are hereby incorporated
herein by reference, in their entirety.
[0019] A bottom hole assembly 32 may be assembled with the tractor
50. The bottom hole assembly may include a measurement while
drilling (MWD) system 34, downhole motor 36, drill bit 38, and
various sensors, all of which are also known in the art. For
example, the drilling system 20 can include sensors and sensor
assemblies such as those shown and described in U.S. Pat. No.
6,367,366 to Bloom et al, entitled "SENSOR ASSEMBLY." The tractor
50 is configured to move within a borehole having the inner surface
42.
[0020] In some embodiments, the circulation assembly 100 is an
independent subassembly that can be joined with other equipment in
a drill string, as schematically illustrated in FIG. 1. Such
embodiments are referred to herein as circulation subs. In some
embodiments, the circulation assembly can be a part or subassembly
of another piece of equipment. For example, the circulation
assembly can comprise a portion of a tractor. In some embodiments,
the circulation sub may be used in a system without a tractor.
[0021] In some embodiments, the circulation assembly 100 directs
all or substantially all fluid downstream in the drill string in a
first mode of operation, and some or all fluid to the annulus 40 in
a second mode. In some embodiments, operation of the circulation
assembly 100 can be repeatedly changed between the modes of
operation. In some embodiments, the circulation assembly can
comprise other modes wherein fluid is apportioned between the
annulus 40 and the downstream drill string.
[0022] In some embodiments, the circulation assembly 100 responds
to pressure cycles to change modes. For example, the circulation
assembly can open every other pump cycle in some embodiments. In
some embodiments, the circulation assembly can have the ability to
open and close the circulation ports as many times as needed.
[0023] In the first mode, all or substantially all fluid desirably
passes unobstructed through the circulation assembly. In some
embodiments, a path to annulus is opened while maintaining
downstream flow in the second mode. In some embodiments, the
circulation assembly can comprise a mode wherein downstream flow is
substantially or completely restricted such that all or
substantially all fluid is directed to the annulus.
[0024] In some embodiments, the circulation assembly can have two
distinct modes: circulation ports open, circulation ports closed.
In some embodiments, the circulation assembly does not require a
ball drop in order to actuate between the two modes, rather it
responds to pressure cycles. In some embodiments, the circulation
ports on the circulation assembly can open every other pump cycle.
The circulation assembly can have the ability to open and close the
circulation ports as many times as needed. During the "circulation
ports open" mode a direct path to annulus can be opened while the
downstream path is unaffected. During the "circulation ports
closed" mode all fluid can be directed downstream.
[0025] A circulation assembly that can repeatedly open and close
fluid flow to the annulus 40 can improve the efficiency of various
downhole operations and is, therefore, of significant benefit to
intervention and drilling operations. The circulation assembly
advantageously can be used in conjunction with downhole tools that
either respond to or produce back pressure. Surface pump rates are
commonly reduced when there are downhole tools that produce back
pressure. The circulation assembly can direct flow to the annulus
when a higher flow rate is desirable, then later redirect all fluid
downstream so that the other tools can resume their normal
operation.
[0026] FIG. 2 schematically illustrates operation of a hydraulic
circuit within some embodiments of the circulation assembly 100. In
the illustrated embodiment, fluid enters the circulation assembly
through a fluid inlet 102 and is then divided between a valve
passage 104 and a bypass flow passage, such as a parallel flow
passage 106. Fluid that enters the valve passage 104 applies
pressure on a valve spool 108 which reacts against a valve spring
122. In some embodiments, the hydraulic circuit includes a valve
index mechanism, described in greater detail below. When the valve
is closed, the fluid is directed solely through the parallel flow
passage 106. When the valve is opened, as shown in FIG. 2, fluid is
permitted to escape to the annulus 40 (FIG. 1) through the exit
passage 112.
[0027] The valve index mechanism 110 desirably has at least a first
position and a second position. If the valve index mechanism is in
the first position, movement of the valve may be restricted and
flow through the valve may be substantially or completely
restricted. If the valve index mechanism is in the second position,
the valve may be allowed open and fluid may exit the circulation
assembly to the annulus. In some embodiments, the valve will remain
open until the pressure is reduced sufficiently that the valve
closes. If the pressure is then increased the valve index mechanism
desirably will be in the first position and restrict the movement
of the valve such that the valve is restricted from opening. As a
result, in this embodiment, all fluid flows through the parallel
flow passage 106 to other elements in the drill string, such as the
bottom hole assembly. If pressure is reduced and then increased,
the process is repeated.
[0028] FIG. 3 is a cross-sectional view of a Repeating Circulation
Sub (RCS) according to one embodiment, which operates in the manner
described in connection with FIG. 2. The illustrated RCS comprises
a housing 113 with an upstream connector 114 at one end and a
downstream connector 116 at the other end. The upstream connector
114 can comprise an inlet 102. The upstream connector 114 can be a
box connector in some embodiments, as illustrated in FIG. 3. The
downstream connector 116 can comprise an outlet 126 to downstream
equipment. The downstream connector 116 can be a pin connector in
some embodiments, as illustrated in FIG. 3. The inlet 102 can be
connected to the outlet 126 by a parallel flow passage 106. The
inlet 102 and the annulus 140 can be connected by a valve passage
104.
[0029] The RCS illustrated in FIG. 3 further comprises a flow
divider 118 at a location downstream from the inlet 102, which
divides the fluid flow between the valve passage 104 and the
parallel flow passage 106, a valve 120, a valve index mechanism
110, a valve spring 122, and a pressure compensated oil chamber
124. In some embodiments, each of these components of the RCS
contributes to the function of the assembly.
[0030] The valve 120 is positioned to open and close the valve
passage 104 to fluid flow. When the valve is open, fluid may flow
outside the RSC to the annulus through a portion 112 of the valve
passage 104. In some embodiments, pressure acting on the valve 120
can be reacted by the valve spring 122 through the valve index
mechanism 110, as illustrated in FIG. 3. The force applied by valve
spring 122 can determine the pressure at which the valve opens.
[0031] The valve index mechanism 110 can alternately allow the
valve to open to vent fluid to the annulus and prevent the valve
from opening. One of skill in the art will appreciate that a
variety of index mechanisms could be used, including those shown
and described in U.S. Pat. No. 7,121,364, entitled "TRACTOR WITH
IMPROVED VALVE SYSTEM," which is hereby incorporated herein by
reference in its entirety.
[0032] The valve index mechanism 110 and valve spring 122 can be
submerged in oil (hydraulic or other) within a sealed chamber 124
providing lubrication. This chamber 124 can be pressure
compensated. The pressure compensated oil chamber 124 can be
bounded by a piston 128 at one end that is exposed to downhole
hydrostatic and formation pressure. In such an arrangement, the
piston 128 can desirably move freely to adjust for changes in
pressure that occur as the tool travels from the surface to the
bottom of the hole. Thus, in some embodiments, each of these
components interacts with the others to allow the RCS to
alternately open and close its circulation ports.
[0033] One of skill in the art will appreciate that other pressure
compensation methods and devices could be employed. Further details
regarding pressure compensated oil chambers are shown and described
in U.S. Pat. No. 6,347,674 to Bloom et al., entitled "ELECTRICALLY
SEQUENCED TRACTOR," and U.S. Pat. No. 6,464,003, entitled "GRIPPER
ASSEMBLY FOR DOWNHOLE TRACTORS," both of which are hereby
incorporated by reference in their entirety.
[0034] FIG. 4 is an enlarged cross-sectional view of the valve 120
and valve index mechanism 110 of the portion IV-IV of FIG. 3. Fluid
that enters the valve passage 104 (FIG. 3) applies pressure on the
valve spool 108, which is reacted through the valve index mechanism
110. In one embodiment, in a first position of the valve index
mechanism, the valve index mechanism 110 inhibits or restricts
movement of the valve spool 108 such that fluid flow is inhibited
or prevented. In a second position, the valve index mechanism
allows the valve to open and fluid exits to annulus. The valve 120
remains open until the pressure applied to the valve spool 108 is
sufficiently reduced that the valve closes. When the pressure is
again increased, the valve index mechanism 110 is in the first
position and, therefore, movement of the valve spool 108 is
restricted such that the valve 120 is not allowed to open. In this
mode, all fluid flows through the parallel flow passage 106 (FIG.
3) to other elements in the drill string. If pressure is reduced
and then increased, the process repeats itself.
[0035] An exemplifying specification has a tool outer diameter of
3.375 in., a tool inner (passage) diameter of 0.75 in., a
subassembly length of 20 in., and a design flow rate of 0-4 BPM.
This exemplifying specification is designed for a wide variety of
coiled tubing operations including acidizing, sandwashing, logging,
moving sliding sleeves, drilling, running perforation guns,
milling, and other typical operations performed in cased and open
hole with restrictions of 3.5 inches or greater. A wide range of
variations on size and performance can be achieved to meet a
particular application. These variations include changes to flow
passages, valve sizes, valve spring (set point), oil type and
chamber size (for depth correction), material selection, connection
type, and inserting a nozzle 130 into the parallel flow passage
106, such as is shown schematically in FIG. 5. Outer diameters
larger and smaller than 3.375 in., are be used in some
applications. For example, the outer diameter is 3.50 in. in some
embodiments, while in other embodiments the outer diameter is 3.00
in.
[0036] FIG. 6 schematically illustrates operation of a circulation
assembly according to some embodiments, which isolates downstream
flow when in a "circulation ports open" mode such that all or
substantially all fluid is delivered to the annulus. Fluid entering
through the inlet 102 is directed through to the valve passage 104.
The fluid applies pressure on a valve spool 108 which reacts
against a valve index mechanism 110. When the valve 120 is in the
position shown in FIG. 6, all or substantially all fluid is
directed to the downstream outlet 126. When the valve is actuated,
fluid is permitted to escape to the annulus 40 through the exit
passage 112.
[0037] In some embodiments, the circulation assembly can receive
and pass a ball to downstream equipment, for example, to actuate
tools in the bottom hole assembly. For example, the parallel flow
passage 106 of the circulation assembly can have a sufficient
diameter to allow the ball to pass therethrough.
[0038] In some embodiments, the circulation assembly can comprise
passages to allow wireline, fiber optic cable, or other
communication to pass through the circulation for communication
with equipment located farther downhole.
[0039] The circulation assembly can be an independent subassembly
of a drill string that can be connected with other equipment in
various configurations, such as the above-described RCS. Thus, the
RCS may be installed in a bottom hole assembly as a single
component or it may be used with other components. Those other
components include, but are not limited to one or more of the
following: tractors, nozzle subs, anti-stall (downhole motor)
tools, various logging tools, perforation guns, sand washing tools,
measurement-while-drilling tool, logging-while-drilling tools
(e.g., gamma, neutron, resistivity, thermal measurement), downhole
motors, drill bits, milling bits, steering assemblies, and special
actuation tools such as tools to move sliding sleeves. The RCS may
be used with other components including ones provided by various
suppliers such as BJ Services, Schlumberger, Halliburton, Baker
Hughes, and Weatherford.
[0040] For example the RCS, a tractor, and a nozzle sub may be used
together. When the RCS is in "circulation ports closed" mode, flow
is directed through the parallel passage to the nozzle sub. A
differential pressure between the inside and outside of the tubing
is created providing power for the tractor to operate. When the RCS
is in "circulation ports open" most of the fluid flow will exit to
annulus through the RCS. Differential pressure will be minimal
between the inside and outside of the tubing so the tractor will
remain off. The tractor can be used to convey tubing past its lock
up to various depths where the RCS can be "opened" to deliver
stimulation treatments, injectivity tests, or perform hole
cleaning.
[0041] In a further example, the RCS can be used with a motor and
mill to facilitate milling of bridge plugs in casing. Typically a
substantial amount of "junk" is left in the hole after a bridge
plug has been milled because pump rates are limited by pressure and
the maximum rate the motor can handle. With the RCS in the bottom
hole assembly, after the bridge plug is milled through the
circulation ports can be opened and pump rate increased to improve
hole cleaning while protecting the motor from damage. This process
will result in a cleaner hole with the potential for improved
production over a longer period of time.
[0042] Although specific exemplifying embodiments have been
described as independent drill string subassemblies, the
circulation assembly in some embodiments forms an integrated part
of a tool such as, for example, a tractor, nozzle sub, logging
tool, perforation gun, sand washing tool,
measurement-while-drilling tool, logging-while-drilling tool,
downhole motor, or special actuation tool such as a tool to move
sliding sleeves.
[0043] The circulation assembly is preferably constructed from
materials that are acid resistant and erosion resistant. For
example, Inconel and beryllium-copper metals can be used in the
connectors, diverter, and housing of the tool; MP35N or Eligiloy
can be used for the valve spring; tungsten carbide can be used in
the valve, and seals can be made from commercially available
elastomers. The materials of the circulation assembly are also
preferably non-magnetic.
[0044] Although specific embodiments and examples have been
illustrated and described, it will be understood by those skilled
in the art that the present inventions extend beyond the
specifically disclosed embodiments to other alternative embodiments
and/or uses of the inventions and obvious modifications and
equivalents thereof. Further, the various features shown and
described can be used alone, or in combination with other disclosed
features in configurations other than as expressly described above.
Thus, it is intended that the scope of the present inventions
herein disclosed should not be limited by the particular disclosed
embodiments described above, but should be determined only by a
fair reading of the claims that follow.
* * * * *