U.S. patent number 3,750,749 [Application Number 05/135,219] was granted by the patent office on 1973-08-07 for swivel control head and method of control.
This patent grant is currently assigned to Halliburton Services. Invention is credited to Richard Lee Giroux.
United States Patent |
3,750,749 |
Giroux |
August 7, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
SWIVEL CONTROL HEAD AND METHOD OF CONTROL
Abstract
A method and apparatus for providing flow control at a wellhead,
characterized by the integration of a remotely operated control
valve with a swivel assembly. The mode of operation and structure
of the control valve are such as to enable the valve to be opened
in response to the imposition of a biasing force and enable a valve
to be maintained open in response to the imposition of a relatively
lower biasing force. The valve may be opened and closed in response
to the operation of a remote control mechanism or alternately may
be opened and/or closed in response to the application of pump
pressure to a conduit communicating with an interior passage of the
swivel assembly.
Inventors: |
Giroux; Richard Lee (Duncan,
OK) |
Assignee: |
Halliburton Services (Duncan,
OK)
|
Family
ID: |
22467085 |
Appl.
No.: |
05/135,219 |
Filed: |
April 19, 1971 |
Current U.S.
Class: |
166/95.1;
166/319; 285/190; 137/615; 166/321; 175/218 |
Current CPC
Class: |
E21B
34/02 (20130101); Y10T 137/8807 (20150401) |
Current International
Class: |
E21B
34/02 (20060101); E21B 34/00 (20060101); E21b
033/00 (); F16l 005/00 () |
Field of
Search: |
;166/75,97,95
;175/216,72,218,71,214 ;251/25,60 ;137/615 ;285/190 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leppink; James A.
Claims
What is claimed is:
1. An apparatus for use in connection with well operations, said
apparatus comprising:
swivel means operable to be connected with a well conduit string
and be supported above well conduit means;
passage means extending generally longitudinally of said swivel
means and operable to be disposed in fluid communication with the
interior of said conduit string;
body means included in said swivel means and operable to permit
rotation of said conduit string relative to said body means;
branch passage means contained in said body means and operable to
communicate with said generally longitudinally extending passage
means;
a tubular valve sleeve carried by said swivel means and operable to
prevent fluid flow between at least a portion of said generally
longitudinally extending passage means and at least a portion of
said brnach passage means;
said valve sleeve being operable to control flow between said
generally longitudinally extending passage means and said branch
passage means while said conduit string is stationary relative to
said well conduit means, and while said conduit string is
undergoing rotational movement relative to said well conduit
means.
2. An apparatus as described in claim 1 further comprising:
resilient biasing means continuously urging said valve sleeve to a
closed position;
remote actuating means operable to selectively actuate said valve
sleeve in said swivel means from a location remote from said swivel
means and said conduit string;
a manually operable plug valve interposed between said body means
of said swivel means and said conduit string and manually operable
to control flow between said conduit string and said generally
longitudinally extending passage means;
valve biasing means operable in response to opening of said valve
sleeve to cause the pressure of fluid in said generally
longitudinally extending passage means to exert a valve opening
biasing force on said valve sleeve so long as said valve sleeve
remains in an open position; and
valve isolating means operable to substantially prevent the
pressure of fluid in said generally longitudinally extending
passage means from exerting a valve opening biasing force on said
valve sleeve when said valve means sleeve is disposed in a closed
position.
3. An apparatus as described in claim 2 further comprising:
pressure responsive surface means carried by said valve sleeve and
operable, in response to an increase of pressure in said branch
conduit means, to exert a valve opening force on said valve sleeve
and cause said valve sleeve to move to an open position.
4. A swivel control unit for controlling the flow of well fluid
from a wellhead comprising:
a generally cylindrical swivel body;
a rotatable, generally tubular body, extending through said swivel
body in generally coaxial relationship therewith;
said generally tubular body including
a central bore through which well fluid is conducted to the
wellhead and
discharge port means through which said well fluid is removed from
said central bore outwardly from said tubular body;
means to secure said swivel body against rotation;
said swivel body including exit port means through which said well
fluid passes;
passage means connecting said discharge port means with said exit
port means;
a tubular valve sleeve supported by said swivel body and said
tubular body and adapted to control the flow of said well fluid
through said passage means from said discharge port means to said
exit port means; and
a manual valve operable to control the flow of well fluid through
said central bore to said discharge port means.
5. The swivel control unit of claim 4, further comprising:
a spring supported by said swivel body; and
an annular, axially extending chamber including said passage means
and defined between said generally tubular body and said swivel
body, within which chamber said spring and said valve sleeve are
supported;
said generally tubular body including pressure port means; and
a portion of said well fluid being operable to pass through said
pressure port means and into said chamber, to thereby communicate
to said valve sleeve the pressure of the fluid flow in said central
bore, so that said thus communicated pressure and the pressure
exerted by said spring act against said valve sleeve tending to
close said valve means sleeve and thereby interrupt the flow of
well fluid through said passage means from said discharge port
means to said exit port.
6. The swivel control unit of claim 5, wherein:
said valve sleeve comprises
a piston including an annular head portion and two annular, axially
extending, sleeve portions directed oppositely away from said head
portion.
7. The swivel control unit of claim 6, wherein:
said chamber further includes a first annular, axially extending
variable volume chamber portion of said annular, axially extending
chamber, into which said portion of said well fluid passes from
said pressure port means;
said first variable volume chamber portion telescopingly receives
one end of one of said piston sleeve portions.
8. The swivel control unit of claim 7, wherein:
said chamber includes a second, annular, axially extending variable
volume chamber portion into which an actuating fluid is passed;
and
said actuating fluid is operable to exert a pressure against said
piston head portion in a direction opposite to the pressure exerted
by said portion of said well fluid and said spring, to thereby open
said valve sleeve and establish the flow of well fluid through said
passage means from said discharge port means to said exit port
means.
9. The swivel control unit of claim 8, wherein:
the pressure exerted on said piston head by said actuating fluid is
less than the pressure exerted on said one end of said one piston
sleeve portion by said portion of said well fluid.
10. The swivel control unit of claim 7, wherein:
said passage means comprises a third, annular, axially extending
variable volume chamber portion of said annular axially extending
chamber; and
the pressure of well fluid in said third chamber portion exerts a
pressure against the other end of said one piston sleeve portion in
a direction opposite to the direction of pressure exerted by said
portion of said well fluid and said spring on said piston, to
thereby tend to balance said piston against the pressure exerted by
said portion of said well fluid.
11. The swivel control unit of claim 10, further including:
means disposed on said swivel body to indicate the opening and
closing of said valve sleeve.
12. The swivel control of claim 10, wherein:
the volume of said first annular axially extending variable volume
chamber is at a maximum and the volumes of said second and third
annular axially extending variable volume chambers are at a minimum
when said valve sleeve is closed; and
the volume of said first annular axially extending variable volume
chamber is at a minimum and the volumes of said second and third
annular axially extending variable volume chambers are at a maximum
when said valve sleeve is open.
13. Well pressure and flow control apparatus for selectively
conducting fluid flow into or out of a well while continuously
allowing simultaneous rotary movement or vertical manipulations, or
both, of the well conduit while flowing said well fluids,
comprising:
inner tubular body means adapted to be connected into a conduit
string;
an outer flow control sleeve telescopingly encircling said inner
body means and adapted to allow said inner body means to rotate
relatively unhindered therein;
said flow control sleeve having an internally expanded lower
portion arranged to form a valve chamber between said lower portion
and said inner body means;
annular cap means attached to the bottom of said expanded portion
of said flow control sleeve and arranged to encircle said inner
body means and form the lower end of said valve chamber;
tubular valve sleeve means located slidably in said valve chamber
and having an upper skirt, a lower skirt and a plurality of
differential pressure areas thereon;
spring means within said valve chamber adapted to work against said
valve sleeve means and bias said valve sleeve means into a closed
position;
well port means in said tubular body communicating from the inner
bore of said tubular body through the wall thereof;
flow passage means through the wall of said flow control sleeve
arranged to communicate with said well port means;
control pressure port means through the wall of said flow control
sleeve and adapted to communicate with said valve chamber; and
said upper skirt on said valve sleeve means being arranged to move
between said tubular body means and said flow control sleeve so
that in an upper position of said valve sleeve means said skirt
passes between said port means and said flow passage means thereby
blocking flow therethrough, and in a lower position said skirt is
moved out from between said port means and said flow passage means
thereby allowing fluid communication therebetween.
14. The apparatus of claim 13 further comprising manually
controlled valve means securedly attached to the lower end of said
tubular body means and having a central bore therethrough in axial
alignment with the inner bore of said tubular body means.
15. The apparatus of claim 13 further comprising cylindrical wear
sleeve means securedly attached exteriorly to said inner tubular
body means between said body means and said flow control sleeve;
thrust bearing means between said tubular body means and said
annular cap means arranged to reduce rotational friction
therebetweeen; and limit stop means in said valve chamber arranged
to limit downward movement of said valve sleeve means.
16. The apparatus of claim 13 wherein said plurality of
differential pressure areas numbers three, with the first said
differential pressure area being arranged for receiving fluid
communicating through said flow passage means, the second said
differential pressure area being arranged to receive actuating
fluid through said control pressure port means, and the third said
differential pressure area being arranged to receive fluid from
said inner bore of said tubular body means; with said first and
second areas arranged to provide forces tending to bias said valve
means into said lower position and said third area arranged to
provide a force tending to bias said valve sleeve means into said
upper position.
17. The apparatus of claim 16 wherein said first area is
substantially equal to said third area and said second area is
substantially larger than said third area, with said first area
arranged to be exposed only to said flow passage means when said
valve sleeve means is in said upper position, and further arranged
to be exposed to said well port means and said flow passage means
when said valve sleeve means is in said lower position.
Description
GENERAL BACKGROUND OF THE INVENTION
This invention relates to a wellhead safety device and a method of
control, and more particularly to a remote control swivel control
unit having a safety valve.
In connection with many well operations a swivel unit is supported
at a wellhead so as to permit fluid flow between the interior of a
well and a surface facility.
Conventionally, such a swivel arrangement provides a body which is
connected by way of conduit means to a surface facility. A conduit
string, rotatably supported relative to the body of the swivel
unit, extends into the well conduit means or casing. The interior
of the swivel unit provides fluid communication between the
interior of the conduit string and the conduit means extending from
the swivel body to the surface facility.
During many well operations it becomes highly desirable to be able
to control the flow of fluid either into or out of the conduit
string.
However, because of the relatively rotatable nature of the swivel
components, and the rotatable and longitudinally movable nature of
the conduit string, substantial complications are presented with
respect to the provision of an accessible, reliable, control
mechanism.
The control over flow through a conduit string, where a swivel
assembly is employed, often becomes significant in connection with
well testing operations.
In many well testing operations, a "testing string" is rotatably
supported relative to the body of a swivel assembly which is
located at the wellhead.
In conducting testing operations with an assembly of this nature
the passage through the swivel assembly is opened to permit well
fluid to flow upwardly from a formation, through the conduit or
testing string, and then through the various communicating passage
means of the swivel assembly to a surface facility which receives
the formation fluid during the testing operations.
In the event that noxious or excessively high pressure fluids
should pass upwardly through the conduit string during such a
testing operation it may be highly desirable to be able to safely
and reliably terminate such a flow of well fluids, especially when
uncontrollable, and prevent such well fluids from passing through
the swivel assembly and to the surface facility.
A variety of proposals have been set forth in the past in
connection with the control over the flow of fluid during such
testing operations. Both manual and remotely operable control valve
concepts have been proposed.
However, such concepts have often been characterized by a degree of
inaccessibility of operating components or by a degree of
structural and operational complexity.
Accordingly, where conduit strings associated with swivel
assemblies have been involved, a need has persisted for an improved
control mechanism which would be reliable and accessible, not
involve excessive structural and/or operational complexity, not
complicate normal operations, and not provide structural
encumbrances in the working area of a wellhead.
In particular, during the testing of oil and gas wells, a dangerous
condition sometimes develops at the wellhead as a result of the
presence of high pressure hydrogen sulfide gas. Natural gas, which
is produced in both oil and gas wells, sometimes contains hydrogen
sulfide. When the hydrogen sulfide laden natural gas, or sour gas
as it is sometimes known, reaches the wellhead, a dangerous
condition may be created if for some reason the gas is allowed to
escape. This is so not only because of the high pressure involved,
but also because hydrogen sulfide is a highly flammable gas which
can deaden the sense of smell and which is dangerously
poisonous.
It thus may become necessary, in order to protect property and
insure the safety of working personnel, to devise means for cutting
off the well flow when the presence of the hydrogen sulfide gas is
detected.
In particular, it would be desirable to provide a remote control
valve to cut off the well flow when the hydrogen sulfide gas is
detected.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention involves the provisions of a remote control
safety valve, embodied as part of a swivel unit. This safety valve
rapidly and reliably responds, when actuated, and the overall unit
allows rotation of a conduit string extending from the swivel
control unit and into the well.
It is a particular object of the invention to provide a swivel
control unit for a wellhead including a safety valve in which the
safety valve is controlled from a point remote from the
wellhead.
A further object of the invention is to provide a valve mechanism,
as heretofore noted, which may be opened in response to the
generation of pump pressure at the wellhead so as to permit the
valve to be forced to an open position and enable fluid to pass
through the swivel assembly, or a conduit means, and into another
portion of a well conduit string.
Another object of the invention is to provide a valve mechanism of
the type heretofore noted which may be opened in response to the
imposition of relatively low pressure actuating fluid and be held
open by the continued application of even lower pressure actuating
fluid.
It is another object of the invention to provide a swivel control
unit for a wellhead including a safety valve in which the well
fluid is utilized to tend to pressure balance the valve in an open
position.
It is still another object of the invention to provide a swivel
control unit for a wellhead including a safety valve in which an
actuating fluid is utilized to open the safety valve and position
the safety valve so that it may be pressure balanced by the well
fluid.
It is a related object of the invention to provide a method of
controlling the flow of well fluid from a wellhead from a remote
area.
It is another related object of the invention to provide a method
of balancing a valve at a wellhead in an open position, utilizing
the well fluid and an externally applied acutating fluid.
In accomplishing at least some of the foregoing objectives, there
is presented through this invention a method of performing well
operations wherein swivel means is connected with a well conduit
string. The swivel means is supported above well conduit means.
This arrangement permits the conduit string to undergo longitudinal
as well as rotary movement relative to the well conduit means.
A passage means is provided in the swivel means which extends
generally longitudinally of the swivel means and is disposed in
fluid communication with the interior of the conduit string. Body
means of the swivel means is arranged at the wellhead so as to
permit rotation of the conduit string. Branch conduit means in the
body means is operable to communicate with the longitudinally
extending passage means of the swivel means.
A valve means carried by the swivel means is operable to control
fluid flow between at least a portion of the longitudinally
extending passage means and at least a portion of the branch
passage means. This valve means is maintained operable to control
flow between the general longitudinally extending passage means and
the branch passage means while the conduit string is stationary
relative to well conduit means and while the conduit string is
undergoing rotational movement relative to the well conduit
means.
An independently significant method aspect of the invention, in the
context of the foregoing basic method, entails the remote actuation
of the valve means. In this additional method aspect of the
invention, a valve biasing means is operable in response to the
opening of the valve means to cause the pressure of fluid in the
longitudinally extending passage means of the swivel means to exert
a valve opening biasing force on the valve means, so long as the
valve means remains in an open position. Additionally, a valve
isolating means remains operable to substantially prevent the
pressure of fluid in the generally longitudinally extending passage
means from exerting a valve opening biasing force on the valve
means when the valve means is disposed in a closed position.
A third, independently significant method aspect of the invention
involves the utilization of a pressure responsive surface means
which is operable in response to an increase of pressure in the
branch conduit means to exert a valve opening force on the valve
means.
Other independently significant facets of the invention relate to
the aforesaid valve mechanism itself and its mode of operation and
to synergistically interacting combinations of apparatus elements
or means which cooperate to perform the method steps heretofore set
forth.
A preferred embodiment of the invention, intended to accomplish at
least some of the foregoing objects, includes a swivel control unit
engaged with a conduit string extending up from a well casing. The
swivel control unit utilizes both the pressure of the well fluid
and the pressure of an externally applied actuating fluid to
control the actuation of a valve contained therein.
The swivel control unit includes a generally cylindrical swivel
body which may be generally secured against rotation and a
generally tubular body or mandrel threadedly engaged with the
conduit string and extending through and disposed in coaxial
relationship with the swivel body. The tubular body or mandrel is
rotatable along with the conduit string, relative to the swivel
body. This relative rotation, as well as the axial movement of the
control unit and conduit string assembly, permits the setting and
releasing and actuation of downhole test tools. Thus, there is
assured a control unit which will permit controlled flow from the
well, if desired, while downhole testing tools are being
manipulated.
The rotatable, generally tubular body includes: a central bore
aligned with the central bore through the conduit string, and
through which well fluid is conveyed to the wellhead; discharge
port means through which the well fluid is removed outwardly from
the tubular body; and pressure port means through which a portion
of the well fluid is directed for communicating the pressure of the
fluid in the central bore to one end of a valve so as to bias the
valve to a closed position.
Between the mandrel and swivel body is an annular, axially
extending chamber. This chamber communicates with an exit port
means in the swivel body as well as with the discharge port means
and the pressure port means.
Supportably received within the chamber are the valve and a spring.
This spring exerts a pressure tending to bias the valve toward a
closed position. In the closed position, the valve is adapted to
interrupt the flow of well fluid from the discharge port means
through the chamber, to the exit port means.
The valve is retained in its closed position by the spring and by
the fluid pressure in the central bore communicated through the
pressure port means and acting against one end of the valve. To
open the valve, actuating fluid is delivered through an inlet port
in the swivel body, from a remote source, into a chamber portion
communicating with another end of the valve. The actuating fluid
exerts a pressure against this other end of the valve, acting in a
direction opposite to the aforesaid communicated pressure of the
well fluid and the spring pressure.
Upon application of the actuating fluid pressure the valve will
open and establish a flow of well fluid from the discharge port
means, through a portion of the chamber, and out the exit port
means. This flow gives rise to a discharge pressure which is
exerted on the same end of the valve as that upon which the
actuating fluid pressure is exerted.
The pressures exerted by the well fluid on the different ends of
the open valve are such that the open valve tends to become
pressure balanced. Thus, the pressure of the actuating fluid may be
reduced, when the valve is open, to a value sufficient to overcome
only the spring pressure. If, for any reason, the actuating fluid
pressure is reduced or removed, or the pressure balance condition
is disturbed, the valve will tend to close.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the present invention will become
apparent from the subsequent detailed description thereof in
connection with the accompanying drawings in which:
FIG. 1 schematically illustrates the swivel control unit of the
present invention suspended from a travelling block and connected
to a conduit string;
FIG. 2 is a vertical cross-sectional view illustrating structural
details of the swivel control unit of the present invention;
FIG. 3 is an enlarged, fragmentary, vertical cross-sectional view
illustrating the inlet port of the swivel body, shown in FIG. 1,
through which actuating fluid is delivered to the second annular
axially extending variable volume chamber portion;
FIG. 4 provides a somewhat further enlarged view of a portion of
FIG. 2 illustrating the valve in its closed position; and
FIG. 5 provides another somewhat further enlarged view of a portion
of FIG. 2, illustrating the valve in its open position, while under
the influence of full actuating fluid pressure.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In describing a preferred embodiment of the invention reference
will be made to a swivel assembly intended to be associated with
and support a well testing string.
Exemplary of well testing strings with which such an assembly may
be incorporated are testing strings or well tool assemblies
featured on pages 140-160 of the Halliburton Sales and Service
Catalog (1968), available from Halliburton Services, Duncan,
Okla.
In arrangements of this nature, the swivel assembly mandrel and/or
the testing string would be supported by wellhead support means
while the swivel assembly body would be connected with stationary
well fluid receiving means located at or near the wellhead.
The general purpose of this arrangement is to provide manipulative
control over the testing string, while also providing control over
the flow of formation fluid upwardly through the testing string and
through the swivel assembly to the well fluid receiving means.
While the invention will be described in this general context, it
will be recognized that its utility is of a broader nature and that
the concepts may be employed, for example, during operations where
fluid is being injected into a well.
Overall Structure
Referring now more particularly to the drawings in which like
numerals are used to indicate like parts throughout the various
views thereof, FIG. 1 schematically illustrates the swivel control
unit 2 in a wellhead installation.
At its lower end, the swivel unit 2 is threadedly connected to a
well conduit or testing string 8, either directly or through an
adaptor 10. The adaptor 10 may include a manual plug valve 12.
Extending outwardly from a generally cylindrical swivel body 16 of
the control unit 2 is an actuating fluid conduit 14. The conduit 14
is indicated as extending to a remote control source (not shown),
from which opening and closing of a safety valve 82 is controlled,
in a manner to be described hereinafter.
As shown in FIGS. 1 and 2, a swivel mandrel 18, journalled within
swivel body 16, is connected at its lower end with conduit string 8
via valve assembly 12 and adaptor 10. The upper end of mandrel 18
is connected with a threaded adaptor 64.
Adaptor 64 may, in turn, be threadably connected with a handling or
support head 4 as generally and schematically shown in FIG. 1. This
support head 4 may include a portion 6 which would be supported by
conventional elevators associated with wellhead hoisting and
lowering gear.
Exemplary of a support head which might be employed is a rig
elevator supported, bail assembly normally used to support an L-T
20 control head, available from Halliburton Services, Duncan, Okla.
A swivel and handling subassembly shown on page 63 of the 1968
Halliburton Sales and Service Catalog and available from
Halliburton Services, Duncan, Okla., might also be employed for
this purpose.
With the general swivel arrangement heretofore described, the
entire axial load of the testing string 8 is carried by the support
head means 4 and mandrel 18. In this manner, the axial weight of
the testing string 8 is not transmitted to the swivel body means 16
or its associated bearing means. Thus, the swivel means 2 will
permit rotary movement of the swivel mandrel 18 and test string 8
relative to the swivel body 16, regardless of the axial load or
weight imposed on swivel mandrel 18.
Swivel Structure
Referring now to FIGS. 2-5, the swivel control unit 2 is shown to
include the generally cylindrical swivel body 16, a generally
tubular body or mandrel 18, and the adaptor 10. The generally
tubular body 18 extends through, is journalled within, and is
coaxial with the generally cylindrical body 16.
Relative rotation of the swivel body 16 and the tubular mandrel 18
is achieved by the rotation of the conduit string 8 which rotates
the tubular mandrel 18. During this rotation, the swivel body 16 is
held relatively stationary by virtue of its connection to conduit
means extending to a stationary, well fluid receiving site, not
shown.
The swivel body 16 includes: an upper section 20 from which a pair
of bosses 22 and 24 radially extend; a cylindrical skirt 26, which
extends axially from the upper section 20; and a swivel nut 28,
which is engageable with the open end of the skirt 26.
The boss 24 includes an internally threaded socket 36 into which a
nipple 38 is threadedly engaged. This nipple connects to conduit
means leading to the well fluid receiving means. The nipple 38 has
a bore 42 which is coaxial with an exit port 44 of the swivel body
16.
Outlet conduit or nipple 38 may be connected with a manifold
control head assembly, not shown. This assembly may comprise
components peripherally encircling swivel body means 16, with the
control head assembly being connected through conduit means to the
stationary well fluid receiving means in the vicinity of the
wellhead. A control head which may be employed for this purpose
comprises an L-T 20 control head described on page 143 of the 1968
Halliburton Sales and Service Catalog, available from Halliburton
Services, Duncan, Okla. The support of this control head may be
facilitated by a control head supporting socket 30 formed in boss
22.
In this arrangement, the conduit connection between the well fluid
receiving site and conduit means 38, or its associated control
head, will tend to prevent rotation of swivel body 16 and its
associated components even though the conduit string 8 and swivel
mandrel 18 are being rotated to effect certain operational
manipulations of the testing string 8.
Such rotational mnaipulations may be effected, for example, by
drivingly engaging a portion of the conduit string 8 with a rotary
table at the wellhead, possibly providing vertical support for the
conduit string with rotary table slips, and operating the rotary
table to effect rotation of the conduit string 8.
Alternatively, full or partial vertical support may be provided by
the adaptor 4 and elevators, with rotation being imparted to the
conduit string 8 by manual manipulation of tongs or wrenches. In
some instances, rotation of string 8 may be effected with all of
the weight of the testing string being supported within the well
casing.
The skirt 26 includes, in addition to a threaded portion at its
open lower end for receiving in threaded engagement therewith the
swivel nut 28, four indicator slots 29 through which the position
of the valve 82 can be observed, as described hereinafter.
The tubular body 18 defines a central bore 46 through which a well
fluid flows.
As the tubular body 18 emerges from the lower end of the swivel
body 16, it flares out to form a shoulder 48 and a skirt section 50
extending therefrom. The shoulder 48 seats a thrust bearing 52 and
an annular sealing ring 54. The bearing 52 fits within a cavity 56
defined by the tubular body 18 and shoulder 48 along with the
swivel nut 28. The sealing ring 54 is provided to confine bearing
lubricant within the cavity 56.
The skirt 50 receives therein an adaptor 10 in threaded engagement
therewith. The adaptor 10 has a skirt section 58 which is
internally threaded for receiving the conduit string 8 in threaded
engagement therewith. The adaptor 10 defines a central bore 60
therethrough which is coaxial with the central bore 46 of the
tubular body 18. The central bore 60 forms a continuation of the
central bore 46 for the flow therethrough of the well fluid.
The adaptor 10 also includes a plug valve 12 which can be actuated
by the rotation of handle 62. The valve 12 provides, therefore, a
means for manually controlling the flow of well fluid through the
central bore 60 and into the central bore 46. Desirably, valve 12
may comprise a LOTORC plug valve available form Halliburton
Services, Duncan, Okla., and described on pages 68-69 of the 1968
Halliburton Sales and Service Catalog.
A plug 66 is threadedly engaged within the top part of the tubular
body 18. This plug 66 prevents outward axial flow of the well fluid
from the central bore 46.
The top part of the tubular body 18 may also threadedly engage the
flange portion 70 of a tubular wear sleeve 68. The tubular sleeve
68, if used, extends through the swivel body 16 to a shoulder 72
which borders the cavity 56. The tubular sleeve 68 and the boss
section 20 define an annular cavity 74 within which a thrust
bearing 76 is located. An annular sealing ring 78 is provided to
confine the bearing lubricant within the cavity 74.
Safety Valve
The swivel body 16 and the mandrel 18 define therebetween an
annular axially extending chamber 80. Within the chamber 80 a valve
82, a compression type coil spring 84 and a valve positioning
sleeve 86 are located. Both the positioning sleeve 86 and the
spring 84 rest against a surface 88 of the swivel nut 28. The upper
end of sleeve 86 provides a stop operable to engage valve 82, when
it moves down, and determines the open valve position.
The valve 82 comprises a piston including an annular head portion
90 and two annular axially extending sleeve portions 92 and 94,
directed oppositely away from the head portion 90.
The annular axially extending chamber 80 provides three annular,
axially extending, variable volume chamber portions.
The first chamber portion 96 is defined by the positioning sleeve
86, the head portion 90, the axially extending sleeve portion 92
and the tubular sleeve 68. The second chamber portion 98 is defined
by the head portion 90, the axially extending sleeve portion 94 and
the swivel body 16. The third chamber portion 100 is defined by the
axially extending sleeve portion 94, the tubular sleeve 68 and the
swivel body 16.
The tubular body 18 is provided with one or a plurality of equally
spaced pressure ports 102 and one or a plurality of equally spaced
discharge ports 104. The tubular sleeve 68 is provided with
openings 106 and 108 which are radially aligned with the pressure
ports 102 and the discharge ports 104, respectively.
In order to ensure that the openings 106 of the wear bushing remain
aligned with the mandrel openings 102, pin means 110, shown in FIG.
2, may intersect certain of the aligned openings 102 and 106 of the
sleeve 68 and the body of mandrel 18 so as to maintain the ports or
openings 102 and 106 in radial alignment.
As will be recognized, sleeve 68, in essence, comprises a wear
bushing and thus may be considered as a mere external portion of
mandrel 18. Thus, a mandrel wear surface may be provided by means
other than the separate wear sleeve 68. For example, aceramic
coating on the exterior of the mandrel 18 might be employed.
The third chamber portion 100 establishes a passage between the
discharge ports 104 and the exit port 44 through which the well
fluid flows when the valve 82 is open.
The actuating fluid which, for example, may be nitrogen, is
directed from a remote source in the vicinity of the wellhead
through the conduit 14. This conduit is threadably engageable with
an inlet port 112 of the swivel body 16. Port 112 communicates with
an annular chamber 114. The annular chamber 114 leads the actuating
fluid into a second chamber portion 98, to thereby enable the fluid
to exert pressure against the upper side of the head portion
90.
Mode of Operation
The mode of operation will be described with reference to FIGS.
3-5.
With the valve 82 closed (FIGS. 3 and 4), and well fluid present in
central bore 46, the first chamber portion 96 fills with well fluid
which is bled from the central bore 46 through the pressure ports
102 and the aligned holes 106. Thus, the pressure of the fluid in
the central bore 46 is communicated to the lower side 90b of the
head portion 90 of the valve 82. The pressure exerted thereby
biases the valve in a closed position and augments the valve
closing bias of spring means 84.
To open the valve, and thereby establish the outward flow of the
well fluid from the central bore 46, an operator located at a
remote source causes an acutating fluid (possibly nitrogen) to be
delivered through the conduit 14, inlet port 112 and annular
passage 114 into the second chamber portion 98 (FIG. 3). The
actuating fluid exerts a pressure against the upper side 90a of the
head portion 90 of the valve member 82.
Because of the relative dimensions of the surface areas 90a and 90b
of the head portion 90 (area 90a being significantly larger) being
acted upon by the communicated pressure and the actuating pressure,
the actuating fluid pressure required to open valve 82 need only be
a fraction of the pressure communicated from passage 46 to cavity
96. That is, the actuating pressure acting on large surface 90a
need only exert a force on piston 82 sufficient to overcome the
force exerted by the communicated pressure acting on small surface
90b and the spring pressure, to thereby cause the valve 82 to open
and assume the position as shown approximately in FIG. 5.
With the valve 82 open, the well fluid establishes a flow through
the exit ports 104 and their aligned openings 108 through the
passage defined by the chamber portion 100 and out the exit port
44. During this outward flow, the well fluid fills the chamber
portion 100, As a result, the pressure of the discharging fluid is
exerted against surface 94a of the outwardly extending sleeve
portion 94 of the valve 82.
The communicated pressure and the discharging pressure now pressure
balance the valve 82 in the open position since area 94a is equal
to area 95b. When the open position of the valve is achieved, which
the operator can determine by looking through the indicator slots
29 to sight the relative location of the sleeve portion 92, the
actuating fluid pressure may be reduced to a point sufficient only
to balance the biasing force exerted by the spring 84. The result
is a balanced valve held in the open position with relatively low
pressure actuating fluid.
An additional operative feature of the valve arrangement is that it
can be pumped open by applying a pressure through the exit port 44
into the third chamber portion 100 (FIG. 4) against the outwardly
extending sleeve portion 94. When sufficient pressure is applied to
area 94a, as permitted by clearance zone 100a shown in FIG. 4, to
overcome the communicated pressure exerted against the lower end
90b of the piston head portion 90 in the first chamber portion 96,
in addition to the spring biasing force, valve opening will occur.
This will allow fluids to be forced back down the well for well
"killing" operations.
Should the pressure in conduit 14 fail, the valve 82 would
automatically close, due to a reduction in pressure in chamber
portion 98.
It is also believed that if the conduit or control head means
connected with passage 42 should rupture or break away from the
swivel assembly 2, a flow of well fluid from passage 46, through
the open conduit means 38 into the atmosphere, would tend to
produce automatic valve closing action even if some spring force
balancing, actuating fluid pressure should exist in cavity 98.
It is believed that the closing phenomena would tend to occur as a
result of a reduction in pressure in well fluid in passage 42 which
would result from the flow of such fluid through the pressure drop
inducing orifice means as defined by exit port 104. Once such a
closing of the valve means 82 occurred, the pressure balancing
valve end 94 would be isolated from the pressure of fluid in
passage 46 such that the valve 82 would tend to stay closed.
Overall Summary of Principal Method and Apparatus Aspects
From the foregoing discussion it will be recognized that the swivel
means 2 is arranged so as to be connected with the well conduit or
testing string 8 and be supported at a wellhead, above the well
casing or conduit means.
The central passage means 46 of the swivel means 2 extends
generally longitudinally of this swivel means and is disposed in
fluid communicating relation with the interior of the conduit
string 8.
The swivel body means 16 is operable to permit rotation of the
conduit string 8. The branch passage means 42 of the swivel body
means 16 is operable to communicate with the longitudinally
extending swivel passage means 46 under the control of valve means
82.
Valve means 82 is carried by swivel means 2 and is operable to
prevent fluid flow between at least a portion of the passage means
46 and at least a portion of the passage means 42. Valve means 82
remains operable to effect this flow control while the conduit
string 8 is stationary relative to the well casing, as well as
while the string 8 is undergoing either rotational and/or
longitudinal movement relative to the well casing.
The remote actuating means provided by conduit means 14, passages
112 and 114, and chamber 98 is operable to effect selective
actuation of the valve means 82 from a location remote from the
swivel means 2 and the testing string 8.
The existence of this remote actuating means notwithstanding, the
valve means 82 is continuously biased to a closed position by
spring means 84 so as to provide a "fail-safe" mode of operation.
In other words, should the pressure of actuating fluid transmitted
through conduit means 14 fail, the spring 84 would ensure automatic
closing of the valve means 82.
Additional manual control is provided by the manually operable plug
valve means 12. This plug valve means 12 is interposed between the
swivel body means 16 and the conduit string 8.
The valve sleeve portion 94, when disposed in the FIG. 5 open valve
position provides a valve biasing means operable to cause the
pressure of fluid in the passage means 46 to exert a valve opening
biasing force on the valve means 82, tending to provide a pressure
balancing phenomena acting on the open valve means. With the
existence of such pressure balancing, i.e., equal pressure of fluid
in passage means 46 acting on opposite axial ends of the valve
means 82, the condition of valve means 82 will be determined by
whether or not the pressure in actuating chamber 98 is sufficient
to balance or overcome the valve closing, biasing influence of
spring means 84.
While the valve means is disposed in the closed disposition
illustrated in FIG. 4, the sleeve means 68 is disposed in
substantially telescoping engagement with portion 94 of valve means
82 so as to function as valve isolating means, i.e., provide a seal
between the extremity 94a of valve means 82 and the pressure of
fluid in passage means 46. This mode of operation of the valve
isolating means 68 will tend to substantially prevent the pressure
of fluid in the passage means 46 from exerting a valve opening
biasing force on the valve means 82, so long as the valve means 82
remains closed. As a result, the pressure of fluid in passage means
46 will augment the valve closing bias of spring means 84 so long
as the valve means 82 remains closed.
Should operations require the injection of fluid into the well, for
example, in order to "kill" a well, the pressure in branch conduit
means 42 may be raised. This raising of pressure will exert a
substantial valve opening biasing force on the pressure responsive
surface means 94a carried by the valve means 82. The force acting
on surface means 94a will exert a valve opening force on the valve
means and cause the valve means to move to an open position.
Under these circumstances, once the valve means 82 has moved to an
open position, it will tend to stabilize in an at least partially
open condition so as to permit a substantially continuous injection
of fluid into the conduit string 8.
The pressure balancing tendency relating to the open condition of
valve means 82, acting either alone or augmented by the
differential piston area phenomena resulting from the fact that the
reaction surface 90a of FIG. 3 (exposed to nitrogen) exceeds the
area of reaction surface 90b (exposed to pressure of fluid in
passage 46), enables the valve means 82 to be maintained in an open
condition with relatively low pressure nitrogen. The differential
area phenomena, i.e., the fact that the area of reaction surface
90a exceeds the area of reaction surface 90b, serves to enable
relatively intermediate, but still low, pressure nitrogen to effect
the initial opening of the valve means 82.
Of course, once the valve means 82 is open, the nitrogen pressure
may be reduced and still hold the valve means open because of the
previously discussed pressure balance phenomena resulting from the
exposure of each axial end of the valve means 86 to the pressure of
fluid in central passage 46.
SUMMARY OF ADVANTAGES AND SCOPE OF THE INVENTION
In describing method and apparatus aspects of the invention,
certain advantages have been made apparent.
A principal advantage resides in the provision of a swivel assembly
including a simple but reliable control valve mechanism which may
be operated from a remote location and which is possessed of
fail-safe characteristics.
Another principal advantage of the invention relates to the manner
in which the pressure balancing phenomena, in the open condition of
the swivel valve means, enables the valve means to be maintained in
an open condition with relatively low pressure actuating fluid.
Another significant advantage of the invention entails the manner
in which the pressure of fluid in branch conduit means 42 may be
substantially increased so as to cause the valve means 82 to open
and enable fluid to be forced downwardly through the testing or
conduit string.
The differential area aspects of the valve enable it to be
initially opened with relatively low pressure in the actuating
fluid.
Other significant advantages also result from the structure and
operational characteristics heretofore noted.
The longitudinal passage 46 is characterized by a substantially
unobstructed, relatively large internal diameter which enables
large flow volumes to be safely and effectively handled.
The nature of this remote operating mechanism is such as to permit
a variety of liquid or gaseous actuating fluids to be employed.
The load supporting swivel mandrel and the thrust bearing
arrangement incorporated in the swivel mechanism enable heavy
string loads to be supported and ensure easy swivel rotation,
concurrent with the provision of prolonged operating life and
minimum maintenance requirements.
The utilization of the remotely actuated safety valve and the
manually controlled plug valve enhance the safety aspects of the
tool in providing alternately operable control techniques.
The slot arrangement in the periphery of the swivel body enable an
operator to determine positively the condition of the safety
valve.
The overall arrangement is such as to virtually eliminate
externally protruding parts which would impede operations or be
vulnerable to damage.
The overall structure of the swivel assembly is such as to enable
it to be safely utilized with relatively high well pressures.
The three separate pressurizing zones operable to act on the valve
means provide predictable and selectively variable control
criteria. The changes of volume of these zones is such as to enable
the valve piston sleeve 94 to be operable to produce the pressure
balancing phenomena under controlled conditions, after the inertia
problems associated with intiating valve movement have been
overcome.
Although the control unit is particularly useful in connection with
sour gas well operations, the remote control safety valve feature
makes it particularly suitable for offshore operations. In general,
offshore vessels float up and down because of wave motion and in
such cases the control head is normally secured high in the rig.
Manual operation of the control head is hazardous under these
circumstances; however, the remote control feature of the present
invention would eliminate this difficulty.
When the invention is to be utilized in connection with well fluids
having a hydrogen sulfide content, improved resistance to hydrogen
sulfide induced embrittlement may be provided by heating treating
components so as to reduce their hardness.
Although the invention has been described in connection with one
preferred and illustrated embodiment, it will be appreciated by
those skilled in the art that additions, modifications,
substitutions and deletions not specifically described may be made
without departing from the spirit and scope of the invention as
defined in the appended claims.
* * * * *