U.S. patent application number 12/813853 was filed with the patent office on 2011-12-15 for method and apparatus for reducing impact force in a ball-seat assembly.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. Invention is credited to Gaurav Agrawal, Mohan L. Soni.
Application Number | 20110303418 12/813853 |
Document ID | / |
Family ID | 45095293 |
Filed Date | 2011-12-15 |
United States Patent
Application |
20110303418 |
Kind Code |
A1 |
Soni; Mohan L. ; et
al. |
December 15, 2011 |
METHOD AND APPARATUS FOR REDUCING IMPACT FORCE IN A BALL-SEAT
ASSEMBLY
Abstract
A method of restricting fluid flow includes: releasing a ball
into a fluid conduit and receiving the ball in a ball receiving
element disposed at the fluid conduit and at least partially
restricting fluid flow; and at least partially reflecting one or
more pressure waves resulting from an impact between the ball and
the ball receiving element by a reflective boundary disposed in the
fluid conduit.
Inventors: |
Soni; Mohan L.; (Katy,
TX) ; Agrawal; Gaurav; (Aurora, CO) |
Assignee: |
BAKER HUGHES INCORPORATED
Houston
TX
|
Family ID: |
45095293 |
Appl. No.: |
12/813853 |
Filed: |
June 11, 2010 |
Current U.S.
Class: |
166/373 ;
166/193 |
Current CPC
Class: |
E21B 23/04 20130101 |
Class at
Publication: |
166/373 ;
166/193 |
International
Class: |
E21B 34/06 20060101
E21B034/06; E21B 33/12 20060101 E21B033/12 |
Claims
1. A method of restricting fluid flow, comprising: releasing a ball
into a fluid conduit and receiving the ball in a ball receiving
element disposed at the fluid conduit and at least partially
restricting fluid flow; and at least partially reflecting one or
more pressure waves resulting from an impact between the ball and
the ball receiving element by a reflective boundary disposed in the
fluid conduit.
2. The method of claim 1, wherein the fluid conduit includes a
first fluid having a first characteristic.
3. The method of claim 2, further comprising injecting a second
fluid into the fluid conduit, the second fluid having a second
characteristic different than the first characteristic and
configured to form an interface between the first fluid and the
second fluid, the interface forming the reflective boundary.
4. The method of claim 3, wherein the characteristic is selected
from at least one of a polarity, a viscosity, a chemical
composition and a physical composition.
5. The method of claim 3, wherein the first characteristic is a
first density and the second characteristic is a second
density.
6. The method of claim 1, wherein at least partially reflecting
includes generating at least one reflected wave that destructively
interferes with the one or more pressure waves.
7. The method of claim 3, wherein the second fluid is injected at a
time that is dependent on a release time of the ball so that the
interface is located at a selected distance relative to the ball at
impact.
8. The method of claim 3, wherein the second fluid is injected at a
time that is dependent on a release time of the ball so that the
interface is located at least one of upstream and downstream of the
ball receiving element at impact.
9. The method of claim 7, further comprising injecting an
additional fluid after the second fluid, the additional fluid
having a characteristic different than the second characteristic so
that the interface is located both upstream and downstream of the
ball receiving element at impact.
10. The method of claim 1, further comprising disposing a carrier
including the actuator assembly in a borehole.
11. An apparatus for restricting fluid flow, comprising: a ball
receiving element disposed in a fluid conduit and configured to
receive a ball that has been advanced through the fluid conduit and
at least partially restrict fluid flow; and a reflective boundary
disposed in the fluid conduit at least partially reflecting one or
more pressure waves resulting from an impact between the ball and
the ball receiving element.
12. The apparatus of claim 11, wherein the boundary at least
partially reflects one or more pressure waves resulting from an
impact between the ball and the ball receiving element, and
generates at least one reflected pressure wave that destructively
interferes with the one or more pressure waves.
13. The apparatus of claim 11, wherein the fluid conduit is
configured to receive a first fluid having a first
characteristic.
14. The apparatus of claim 13, wherein the fluid conduit is
configured to receive a second fluid, the second fluid having a
second characteristic different than the first characteristic and
configured to form an interface between the first fluid and the
second fluid, the interface forming the reflective boundary.
15. The apparatus of claim 14, wherein the characteristic is
selected from at least one of a polarity, a viscosity, a chemical
composition and a physical composition.
16. The apparatus of claim 14, wherein the first characteristic is
a first density and the second characteristic is a second
density.
17. The apparatus of claim 14, further comprising a processor
configured to inject the second fluid at a time that is dependent
on a release time of the ball so that the interface is located at a
selected distance relative to the ball at impact.
18. The apparatus of claim 14, further comprising a processor
configured to inject the second fluid at a time that is dependent
on a release time of the ball so that the interface is located at
least one of upstream and downstream of the ball receiving element
at impact.
19. The apparatus of claim 18, wherein the processor is configured
to inject an additional fluid after the second fluid, the
additional fluid having a characteristic different than the second
characteristic so that the interface is located both upstream and
downstream of the ball receiving element at impact.
20. The apparatus of claim 11, further comprising a carrier
including the ball receiving element and the fluid conduit, the
carrier configured to be disposed in a borehole.
Description
BACKGROUND
[0001] In the drilling and completion industry and for example in
hydrocarbon exploration and recovery operations, a variety of
components and tools are lowered into a borehole for various
operations such as production operations, for example. Some
downhole tools utilize ball-seat assemblies to act as a valve or
actuator. Ball-seat assemblies are used with, for example,
hydraulic disconnects, circulating subs and inflatable packers.
[0002] Actuation of a ball-seat assembly generally includes
releasing a ball or other plug from a releasing mechanism and
allowing the ball to drop onto the ball seat and restrict a fluid
conduit. The impact between the ball and the ball seat can produce
pressure waves, which can cause wear and/or damage to the ball-seat
assembly and other components. For example, initial impact is
generally the most severe and is compounded by the suction pressure
on the ball seat due to an outgoing expansion wave downstream of
the seating area.
SUMMARY
[0003] A method of restricting fluid flow includes: releasing a
ball into a fluid conduit and receiving the ball in a ball
receiving element disposed at the fluid conduit and at least
partially restricting fluid flow; and at least partially reflecting
one or more pressure waves resulting from an impact between the
ball and the ball receiving element by a reflective boundary
disposed in the fluid conduit.
[0004] An apparatus for restricting fluid flow includes: a ball
receiving element disposed in a fluid conduit and configured to
receive a ball that has been advanced through the fluid conduit and
at least partially restrict fluid flow; and a reflective boundary
disposed in the fluid conduit at least partially reflecting one or
more pressure waves resulting from an impact between the ball and
the ball receiving element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The following descriptions should not be considered limiting
in any way. With reference to the accompanying drawings, like
elements are numbered alike:
[0006] FIG. 1 is a cross-sectional view of a subterranean well
drilling, well logging, evaluation, exploration and/or production
system
[0007] FIG. 2 is a flow diagram depicting a method of restricting
fluid flow in a conduit;
[0008] FIG. 3 is a cross-sectional view of an embodiment of a
ball-seat assembly including a first and a second fluid injected
into a conduit of the ball-seat assembly; and
[0009] FIG. 4 is a cross-sectional view of an embodiment of a
ball-seat assembly including a first and second fluid injected into
a conduit of the ball-seat assembly.
DETAILED DESCRIPTION
[0010] The apparatuses, systems and methods described herein
provide for controlling downhole fluid flow and mitigating pressure
waves caused by actuation of a ball-seat assembly. A downhole
actuator assembly includes a conduit having a longitudinal
component to guide a ball released into the conduit to a ball
receiving element such as a ball seat. A reflective boundary
disposed in the conduit at least partially reflects one or more
pressure waves resulting from an impact between the ball and the
ball receiving element. One embodiment of a method of reducing
pressure waves includes pumping a first downhole fluid into the
conduit, followed by pumping a second downhole fluid that has a
characteristic that is different than the characteristic of the
first downhole fluid, which creates a reflective boundary from the
interface between the first and second fluids that acts to reflect
incident pressure waves created by an impact between the ball and
the ball receiving element. The reflected pressure waves
destructively interfere with the incident pressure waves to reduce
the amplitude of the incident pressure waves and reduce wear on
downhole components such as the ball and the ball seat. Examples of
such characteristics include density, viscosity, polarity, and
chemical and/or physical differences causing the fluids to resist
mixing or combining.
[0011] Referring to FIG. 1, an exemplary embodiment of a
subterranean well drilling, well logging, evaluation, exploration
and/or production system 10 includes a borehole string 12 such as a
production string that is shown disposed in a borehole 14 that
penetrates at least one earth formation 16 during a subterranean
operation. The borehole string may include any type of carrier,
such as a downhole sub or wireline. A tool 18, such as a ball seat
sub, includes a housing 20 having a longitudinal bore or fluid
conduit 22. A ball-seat assembly includes a ball receiving element
such as a ball seat 24 included in the conduit 22 to retain a ball
26 that is released into the conduit 14. In one embodiment, the
ball 26 is a spherical metal or plastic plug, although "ball" may
refer to any type of moveable or droppable plugging element, such
as a drop plug, and may take any desired shape or size. Actuation
of the ball seat assembly includes releasing the ball into the
fluid conduit 14, for example by dropping the ball 18 into and/or
pumping the ball 18 through the fluid conduit 14 from a surface or
downhole location. The ball 18 falls and/or is advanced by downhole
fluid toward the ball seat 16 and is seated on the ball seat 16 to
restrict fluid flow through the conduit 14.
[0012] The ball seat 24 may be an annular component connected to
the conduit 22, or any other device or configuration providing a
restriction in the diameter or cross-sectional area of the conduit
22 sufficient to prevent the ball 26 from passing therethrough. For
example, the ball seat 24 may be attached to the inner surface of
the conduit 22 or include a reduced diameter portion of the conduit
22.
[0013] In one embodiment, the tool 18 is configured to be in fluid
communication with at least one pumping device 28 that is
configured to introduce into and/or advance a fluid through the
borehole string 12 and the fluid conduit 22. In one embodiment, a
processor or other device, such as a surface processing unit 30 is
in operable communication with the pumping device 28 and/or the
tool 18 to communicate with and control operation of the pumping
device 28 and/or the ball-seat assembly. The downhole tool 10 is
not limited to that described herein. The borehole string 12 and/or
the tool 18 may include any tool, carrier or component that
includes a ball seat assembly. In addition, the tool 18 is not
limited to components configured for downhole use.
[0014] FIG. 2 illustrates a method 40 of restricting fluid flow in
a component. The method includes, for example, actuating a valve or
packer in a downhole assembly. The method 40 includes one or more
stages 41-43. Although the method is described in conjunction with
the system 10 and the downhole tool 18, the method can be utilized
in conjunction with any device or system (configured for downhole
or surface use) that utilizes a ball-seat assembly.
[0015] In the first stage 41, in one embodiment, the downhole tool
18 is deployed downhole and advanced along the borehole 14 to a
desired position, such as via a borehole string 12 or a wireline.
In the second stage 42, a first downhole fluid having a first
characteristic such as a first density is injected, pumped or
otherwise introduced into the fluid conduit 22. In the third stage
43, a second downhole fluid having a second characteristic such as
a second density is introduced into the fluid conduit 22 at a time
proximate to or otherwise dependent on a time of release of the
ball 18 or an anticipated time of actuation of the ball-seat
assembly. In the fourth stage 44, the ball-seat assembly is
actuated by releasing the ball 26 into the conduit 22, for example
by dropping the ball 18 into the conduit 14 and/or pumping the ball
18 through the conduit 14. The ball 18 advances through the conduit
14 and impacts the ball seat 16. The different characteristics of
the first and second downhole fluids create an interface or
boundary that acts to reflect one or more incident pressure waves
resulting from an impact between the ball 26 and the ball seat 24.
The pressure waves destructively interfere with the incident
pressure waves and dissipate the pressure waves to reduce the
severity and duration of loads created by the pressure waves. This
dissipation may also reduce the suction pressure on the ball-seat
assembly due to the outgoing expansion wave downstream of the
seating area. The different characteristics may be any
characteristics sufficient to create a reflective boundary between
the first and second fluids. For example, the fluids may have
different densities or viscosities. In one embodiment, the fluids
may have different chemical polarities. For example, the first
fluid may be a generally polar fluid such as a water-based fluid
and the second fluid may be a generally non-polar fluid such as an
oil-based fluid.
[0016] An embodiment of the method 40 is described in conjunction
with FIG. 3, which shows an embodiment of a ball-seat assembly 50.
In this embodiment, a first downhole fluid 52 is pumped into the
fluid conduit 22 via, for example, the borehole string 12. The ball
26 is released upon actuation of the ball-seat assembly 50, and at
a selected time after ball release, a second downhole fluid 54 is
pumped into the conduit 22. The first fluid 52 pumped ahead of the
ball 26 has a first density `A` that is different than a second
density `B` of the second fluid 54 pumped right after the ball. In
one embodiment, the density A is greater than the density B,
although the density A may be less than the density B in other
embodiments. Various types of fluids may be used, such as water
having a density of 8.3 pounds per gallon (ppg) and various
drilling muds, such as water based drilling fluids having various
densities (e.g., 16.5 ppg), and oil based muds which may have
various densities ranging from, for example, 8-18 ppg.
[0017] The interface between fluids having the densities A and B
results in a boundary 56 that provides a surface for the reflection
of the incident pressure wave(s). Reflected pressure waves
reflected from the boundary 56 at least partially cancel out the
original pressure wave(s) created at the time of impact and reduces
the net pressure resulting from impact.
[0018] The pumping of the second fluid 54 is initiated at a time so
that the boundary 56 advances with the ball 26 at a selected
distance from the ball 26. In this way, the distance of the
boundary 56 from the ball 26 and the ball seat 24 at the time of
impact can be controlled. For example, the injection or pumping of
the second fluid 54 is triggered prior to or in anticipation of
ball-seat actuation so that the boundary 56 is formed upstream
and/or downstream of the ball 26. The pumping of the second fluid
54 may be initiated so that the boundary 56 is proximate to the
ball 26, so that the boundary 56 is located proximate to the ball
seat 24 at time of impact to rapidly dissipate the incident
pressure wave(s).
[0019] Another embodiment of the method 40 is described in
conjunction with FIG. 4. In this embodiment, the first fluid 52 of
density `A` is pumped first, followed by the second fluid 54 of
density `B` which carries the ball. Density B may be, for example,
greater than density A. In one embodiment, the second fluid 54 is
injected at a time relative to ball-seat assembly actuation so that
the ball 26 is carried by the second fluid and the boundary 56 is
downhole of the ball 26 but still close to the ball 26. Upon
impact, the boundary 56 is downhole of the ball 26 and the incident
pressure wave is a negative expansion waveform but the dense fluid
reflection is a positive or compression wave that will tend to
cancel the tensile or negative wave. Thus the amount of force on
the ball 26 will be less because the pulling force from below will
be cancelled out by the reflected waves. In one embodiment, the
first fluid 52 of density `A` (or another fluid having a density
different than the density `B`) is additionally injected or pumped
following the second fluid 54. The density difference between A and
B thus creates a density contrast, i.e., a boundary 56, relative to
the ball at both upstream and downstream locations. Impact of the
ball 26 upon the ball seat 24 creates a pressure wave in both the
upstream and downstream directions, which are at least partially
reflected and dissipated by the boundaries 56. Thus the net
pressure on the ball-seat assembly 50 resulting from the impact is
reduced by successively pumping different density fluids.
[0020] The apparatuses and methods described herein provide various
advantages over existing processing methods and devices. Wear on
the ball-seat assembly, which is a function of force over distance
and time, can be reduced by reducing the force of the ball of the
seat through the reduction in amplitude of the pressure wave(s).
This reduction directly reduces the probability of ball-seat damage
and conversely improves its reliability. The reduction of pressure
waves affecting the ball-seat assembly can enable the use of a
wider range of construction materials and reduce the cost and
complexity of ball-seat design, for example by reducing the need
for relatively complex ball seat designs to reduce impact. In
addition, the apparatuses and methods can allow for the ball seat
to have a larger inner diameter due to the reduced contact
stress.
[0021] While the invention has been described with reference to
exemplary embodiments, it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications will be
appreciated by those skilled in the art to adapt a particular
instrument, situation or material to the teachings of the invention
without departing from the essential scope thereof. Therefore, it
is intended that the invention not be limited to the particular
embodiment disclosed as the best mode contemplated for carrying out
this invention.
* * * * *