U.S. patent number 3,633,667 [Application Number 04/882,992] was granted by the patent office on 1972-01-11 for subsea wellhead system.
This patent grant is currently assigned to Deep Oil Technology, Inc.. Invention is credited to Chester B. Falkner, Jr..
United States Patent |
3,633,667 |
Falkner, Jr. |
January 11, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
SUBSEA WELLHEAD SYSTEM
Abstract
An apparatus and method for a subsea wellhead station having one
or more producing well holes wherein an oil production control unit
is separate from and adjacent to a wellhead unit for a well hole,
each of said units being removable for repair and maintenance at a
remote location independently of the other unit. The production
control unit contains necessary equipment affording remote control
of production of oil, directing such production into test or
collection lines, monitoring pressures of production oil from its
associated well hole, controlling gas injection into the well hole,
and maintaining and controlling desired production oil pressure
conditions.
Inventors: |
Falkner, Jr.; Chester B.
(Whittier, CA) |
Assignee: |
Deep Oil Technology, Inc. (Long
Beach, CA)
|
Family
ID: |
25381766 |
Appl.
No.: |
04/882,992 |
Filed: |
December 8, 1969 |
Current U.S.
Class: |
166/366; 166/363;
166/365; 285/18 |
Current CPC
Class: |
E21B
33/035 (20130101); E21B 43/017 (20130101); E21B
41/08 (20130101) |
Current International
Class: |
E21B
33/035 (20060101); E21B 33/03 (20060101); E21B
43/00 (20060101); E21B 43/017 (20060101); E21b
043/01 () |
Field of
Search: |
;166/.5,.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Champion; Marvin A.
Assistant Examiner: Favreau; Richard E.
Claims
I claim:
1. A subsea wellhead system comprising:
a wellhead template assembly including:
a wellhead means adapted to be associated with a well hole and
including a removable wellhead unitary portion, and
a production control means spaced and separated from said wellhead
means and including a removable production control unitary
portion;
means operably interconnecting said wellhead and production control
means;
each of said wellhead and production control unitary portions being
adapted to be isolated from the wellhead system;
whereby a selected one of said removable portions is recoverable
for maintenance above surface without disturbing the remainder of
the wellhead template assembly.
2. A wellhead system as stated in claim 1 wherein said wellhead
template assembly includes a plurality of sets of such wellhead and
production control means; and
a common manifold means connected to each of the production control
means.
3. A wellhead system as stated in claim 1 wherein said production
control unitary portions includes
valve means for controlling and regulating flow of fluids into and
out of the well hole.
4. A subsea wellhead system as stated in claim 1 including means
operably interconnecting said production control means with a
remote sea surface location for operating said production control
means at said remote location.
5. A wellhead system as stated in claim 1 wherein said wellhead
means includes control valves for said production flow line
operable into fail-safe closed position and in closed position
permitting removal of said production control means.
6. In a subsea wellhead system for a plurality of relatively
closely spaced well holes in an ocean floor, the combination
of:
a wellhead template assembly at said ocean floor and including
template frame means;
a wellhead means associated with each well hole;
a production control means supported on said frame means adjacent
to and separate from said wellhead means;
a manifold means connecting each of said production control
means;
each of said wellhead means including a removable recoverable unit
comprising valve means for well fluids;
each of said production control means including a removable unit
including flow control means for said well fluids, and
control means for said valve means in said wellhead means and said
production control means; and
connecting lines for conducting well fluids between said wellhead
means and production control means.
7. In a wellhead system including a plurality of well holes in a
preselected arrangement, the provision of:
a wellhead template frame construction including a plurality of
conductor guide means arranged in the same pattern as said well
holes;
means on each conductor guide means for connecting a wellhead unit
thereto;
a production control unit carried by said template frame
construction adjacent to each conductor guide means and adapted to
be connected to an associated wellhead unit;
manifold means carried by the template frame construction and
connected with each production control unit for flow of production
oil and gas;
each of said production control units including separable portions,
one portion including valve means for isolating said production
control unit from said manifold means; and
means releasably interconnecting said other production control unit
portion to said one portion for recovery of said other portion for
maintenance thereof.
8. A wellhead system as stated in claim 7 including:
a wellhead unit connected to each of said conductor guide means and
associated well hole; and
means releasably interconnecting each of said associated wellhead
units and production control units for flow of production oil and
gas therebetween and for control of such flow.
9. In a method of establishing a wellhead system for a subsea well
installation having a plurality of well holes arranged in a
preselected, compact pattern, the steps of:
placing a prefabricated wellhead template construction having
conductor guide means arranged in said preselected pattern in
registered operative relation with said well holes, said wellhead
template construction including separable removable production
control units in adjacent relation to said conductor guide
means;
connecting a preassembled wellhead unit to each well hole and
conductor guide means therefor;
releasably interconnecting each of said wellhead units and adjacent
production control units with production oil and gas flow
lines;
and releasably interconnecting each of said wellhead units and
adjacent production control unit with control means;
whereby each of said production control units may be independently
isolated from its associated wellhead unit and wellhead template
frame construction for recovery thereof.
10. In a method of establishing and maintaining a wellhead system
for a subsea well installation which includes a plurality of well
hole locations in a selected pattern, the steps of:
providing a wellhead template construction having conductor guide
tubes arranged in a pattern corresponding to said selected well
hole pattern and carrying production control means including
separable movable production control units;
lowering and releasably connecting a wellhead means including a
separable wellhead unit to said conductor guide tubes;
releasably interconnecting said wellhead means and said production
control means for control of gas and oil flow lines and control
means therefor and for isolation of one of said units from the
other unit;
and removing a selected one of said units for maintenance
thereof.
11. In a method as stated in claim 10 including the steps of:
manifolding the gas and oil flow lines of a plurality of production
control means whereby one of said units selected for maintenance
may be independently isolated for removal and recovery thereof
while said other units retain their operable condition
12. In a wellhead system including a plurality of well holes
normally adapted to be simultaneously operated, the combination
of:
a wellhead template frame structure;
wellhead means including a separate wellhead unitary portion on
said frame structure and adapted to be associated with a well
hole;
a production control means including a separable production control
unitary portion spaced from said wellhead means;
means operably interconnecting gas and oil flow lines of said
wellhead means and production control means;
control means for said wellhead means and production control means
and including
means for isolating at least one of said separable unitary portions
whereby said one separable portion is recoverable and removable for
above-surface maintenance.
13. In a wellhead system as stated in claim 12 including:
a plurality of wellhead means and a plurality of production control
means associated therewith;
and common manifold means for said plurality of production control
means.
14. In a wellhead system as stated in claim 13 including
track means spaced from said production control means and extending
from one production control means to the adjacent production
control means;
means on said wellhead means and production control means for
releasing said wellhead unitary portion and production control
unitary portion respectively,
said release means on said wellhead means and production control
means being accessible from said track means and adapted for
separate independent release of a unitary portion with respect to
the other unitary portion.
15. A subsea wellhead system comprising:
a wellhead template system comprising:
a plurality of wellhead means each adapted to be associated with a
well hole, and
a plurality of production control means spaced and separated from
said wellhead means;
means operably interconnecting said wellhead and production control
means;
each production control means including means for selectively
directing production fluid into a common production manifold or
test flow line;
each of said wellhead and production control means including
a removable unit adapted to be isolated from the wellhead
system,
whereby a selected one of said removable units is recoverable for
maintenance above surface without disturbing the remainder of the
wellhead assembly.
Description
BACKGROUND OF THE INVENTION
Prior wellhead structures used at producing well holes have
included a unitary complex arrangement of Christmas tree and
production control equipment combined into a single assembly at the
top of a well hole. In other prior installations, production
control equipment was utilized within the well hole and was
separated from Christmas tree equipment located at the top of the
well hole. In still other prior installations, production control
equipment was not employed at the well site.
Such prior proposed systems include several disadvantages,
especially when utilized in a subsea wellhead installation where
the wellhead was located beneath the surface of the ocean and was
not readily accessible. In installations employing a single unitary
assembly of Christmas tree and production control equipment before
a component part thereof or the unit could be removed for
maintenance or repair, entry was required into the well bore to
plug the well. In the installations where control equipment was
operable within the well or downhole, tubing was required to be
withdrawn in order to maintain or repair faulty downhole equipment.
Moreover, in such downhole production control installations, the
flexibility of the control operations were substantially limited
and reduced.
In those installations where control equipment was not installed at
the well site, the lack of such production control equipment
increased safety hazards and resulting damages to the well or flow
line systems in the event the production flow became uncontrolled,
an prohibited gathering or providing a common manifold for
production fluids from several wells having different producing
conditions. The effect of such disadvantages of such prior proposed
production installations in a subsea environment was greatly
increased and resulted in a substantial increase in costs of labor
and material in order to provide maintenance and repair for
production control equipment of a subsea well.
SUMMARY OF THE INVENTION
The present invention relates to a subsea wellhead system which is
so constructed and arranged that repair and maintenance of the
production control equipment for an associated well hole may be
readily accomplished without the problems and disadvantages of
prior proposed subsea production control installations. The present
invention contemplates a novel arrangement of Christmas tree
equipment or a wellhead unit which is associated with a subsea well
hole and separate from and adjacent thereto is a production control
unit which is readily disconnected and removable from its location
adjacent the wellhead unit so that it may be raised to the surface
of the ocean for maintenance and repair above water and at a remote
station. The subsea wellhead system contemplated by the present
invention does not require entry into the well per se to service
items which commonly need maintenance or repair, and therefore,
does not require withdrawal of production tubing from the well. The
present wellhead system is so arranged that where a plurality of
adjacent wells are being produced the production oil flow
conditions in each well may be readily monitored and regulated to
provide the most effective production characteristics for that well
and may be also regulated so that the production oil flow may be
controlled so that the flow may join production oil flowing from
adjacent wells with the minimum interference or interaction between
the flow and pressure conditions of the adjacent wells. The
arrangement of the present wellhead system provides a method and a
construction whereby unit replacement can be quickly and readily
made so that repair and maintenance can be performed in a suitably
equipped maintenance shop.
The principal object of the present invention therefore is to
disclose and provide a novel subsea wellhead system in which a
wellhead unit or a production control unit may be readily
disassembled from the wellhead structure without interference with
the other unit for removal for repair and maintenance at a remote
location.
An object of the present invention is to disclose and provide a
subsea wellhead system wherein equipment normally requiring
periodical service and maintenance is located in a production
control unit which is readily removable from the wellhead
assembly.
Another object of the invention is to disclose and provide a subsea
wellhead system for a plurality of wellheads wherein a selected
wellhead may be serviced and maintained while the remaining
wellheads remain in production.
Another object of the invention is to disclose and provide a subsea
wellhead system wherein a plurality of production control units,
each being adjacent to an associated wellhead, may direct their
production flow into a common manifold in such a manner that
production flow pressure may vary from wellhead to wellhead
A further object of the invention is to disclose and provide an
integral power system in the production control unit for operating
valves, controllers and regulators on both the wellhead unit and
the production control unit for effectively regulating the
production of oil from a well hole.
Other objects of the invention include an arrangement of wellheads
and associated production control units which facilitates
maintenance and control, facilitates underwater manipulation of
various connections of the wellhead and production control units,
permits switching of production fluid from the well into different
parts of a common production manifold for permitting testing of
production fluid from a selected well, and controls and regulates
the production control equipment and wellhead equipment from a
remote location such as a vessel on the surface of the ocean.
A specific object of the invention is to disclose and provide a
separable removable subsea unit for a wellhead which is readily
operable under water and may employ pressure-equilizing oil-filled
compartments for critical components and which may be readily
removed as a unit by remote actuated devices.
Various other objects and advantages of the present invention will
be readily apparent from the following description of the drawings
in which an exemplary embodiment of the invention is shown.
IN THE DRAWINGS
FIG. 1 is a perspective view of an exemplary wellhead system
embodying the present invention, some of the wellhead units being
omitted for clarity;
FIG. 2 is an enlarged perspective view of a wellhead unit and an
associated production control unit for a well hole in the system
shown in FIG. 1;
FIG. 3 is a schematic flow diagram showing operation of the
wellhead unit and production control unit shown in FIG. 2 for a
well hole;
FIG. 4 is a fragmentary sectional view taken in a vertical plane
passing through the axis of the wellhead unit shown in FIG. 2 and
generally indicated by the line IV--IV of FIG. 2;
FIG. 5 is a fragmentary sectional view taken in the plane indicated
by line V--V of FIG. 4;
FIG. 6 is a fragmentary sectional view taken in the planes
indicated by lines VI--VI of FIG. 5; and
FIG. 7 is a fragmentary sectional view of a pipe connection taken
in a vertical plane generally indicate by line VII--VII of FIG.
2.
In FIG. 1 there is illustrated an exemplary subsea wellhead system
generally indicated at 10 embodying the present invention. In such
subsea wellhead system a plurality of well holes generally
indicated at 11 are drilled in an ocean floor in a preselected
pattern and arrangement. In this example, the well holes 11 are
arranged in spaced parallel rows, the well hole in one row being
longitudinally offset from the well hole in the adjacent row. Each
well hole may include an outer well casing which extends above the
ocean floor surface and which may support in well-known manner
inner casings and production pipe (not shown). After drilling, each
well hole may be capped in well-known manner. It will be readily
understood that the arrangement of well holes 11 may be varied with
respect to pattern, however in the practice of the present
invention it is desirable that the upper heads of well holes by
closely grouped or clustered within a selected area at the template
but deflected or directionally drilled as required below the sea
floor to facilitate use of a wellhead template frame construction
generally indicated at 12.
Template frame construction 12 may be prefabricated and
preassembled at a convenient work location above water to
correspond with the preselected pattern of well holes 11. When
template frame construction 12 is completed as fully described
later, the entire assembly may be lowered by suitable well-known
means into operative relation with well holes 11. One of the
important features of this invention is the provision on template
construction 12 of readily removable production control units 14
which are separate from and adjacent to and interconnected by
connecting lines 15 to wellhead units 16 which are similarly
readily removable and recoverable for service and maintenance above
water. In the compact relatively closely clustered arrangement of
well holes, the production control units are readily operable to
facilitate controlling production flow and manifolding of such
production flow from the several well holes to provide an efficient
wellhead production operation as described in detail hereafter.
Wellhead template frame construction 12 may comprise a suitable
braced and reinforced frame means 20 of metal members of suitable
section and including base members 21 adapted to be supported on or
at an ocean floor. Along opposite longitudinal side portions of
frame 20 are supported spaced horizontal parallel rail members 22
which provide a track for an underwater manipulating device or
robot (not shown) which may travel along said rail members for
stopping opposite a production control unit 14 or wellhead unit 16
for work thereon as required. Between the side rail members 22 is a
longitudinal opening or space within which are supported from frame
means 20 a plurality of vertically disposed conductor guide means
24, each conductor guide 24 being positionable at an associated
well hole 11 and readily ensleeved over the upwardly extending
outer casing portion of the well hole 11. Frame means 20 also
supports in prearranged assembly manifold means generally indicated
at 26 which comprises in this example a plurality of flow pipes 27,
28 and 29 arranged in parallel relation and extending around the
outer portions of said longitudinal opening for connection to each
production control unit. At one end of frame means 20 the pipes 27,
28 and 29 may be provided with suitable known flared pipe connector
or coupling means 30 for connection to flow lines for conducting
production flow, gas, and test flows to a remote location. The
remote location for production flow may be an underground storage
tank, a storage platform station, or suitable tank storage means at
the surface of the water.
Frame means 20 also carries a control duct means 32 provided with
selected suitable control means which may be connected to each
production control unit 14 and also through suitable lines 34 to a
remote control station 35 indicated exemplarily as a vessel at the
surface of the water. Depending upon location of the subsea
wellhead system 10, the remote location for the controls may be on
land, on a vessel, or at a suitably supported or anchored above
surface platform station. It will be understood that the remote
control means employed may comprise various well-known control
means, such as an electrical cable extending from the remote
location to the subsea wellhead assembly, an acoustical system, or
a fluid pressure system employing hydraulic or pneumatic means to
control the production control units and wellhead units as
described more fully hereafter.
As indicated above, the wellhead template frame construction means
12 equipped with the conduit guides 24, manifold pipe means 26,
production control units 14, and control conduit means 32 may be
preassembled and prefabricated out of water and then lowered into
operative position and relationship with respect to the pattern of
well holes 11. When the template means 12 is so positioned and
located, wellhead units 16 may be lowered into assembly with each
conductor guide 24 and the wellhead equipment enclosed thereby. As
best viewed in FIG. 2 each well hole 11 includes an outer casing 40
which encloses a production tubing 41 defining an annular chamber
42 within outer casing 40. At a selected depth of approximately 300
feet more or less beneath the ocean floor a normally open
production tubing string valve means 43 may be provided, said valve
means 43 being of suitable well-known ball valve type for
controlling production flow of oil throughout the production tubing
string 41 and capable of shutting off said flow upon closure
thereof by control means described hereafter. Adjacent valve means
43 there may be provided in the annular space 42 a gasline 45
having a gas valve 46 for introducing gas into the production pipe
string 41 for lift purposes. At selected intervals above valve
means 43 gasolines 47 may be provided in annular space 42 for
injection at suitable vertically spaced intervals into production
pipe string 41 of injection gas for artificial lift purposes.
At the top of conductor guide 24 and outer casing 40 the wellhead
may include an upstanding axial mandrel 50 enclosing well-known
means for providing a connection to the production pipe string 41
and casing means within the conductor guide tube. The upstanding
mandrel 50 is part of a wellhead connector means described and
claimed in copending application Ser. No. 775,872 filed and owned
by a common assignee, said application being incorporated by
reference herein. In general, the wellhead connector means
generally indicated at 51 comprises in addition to upstanding
mandrel 50 a barrel 52 having a downwardly and outwardly flared
skirt 53 to facilitate alignment entry of the top tapered portion
54 of the mandrel into the barrel 52. In fully inserted position
tapered end 54 seats against a correspondingly tapered internal
sleeve 55 carried by barrel 52 at its top portion. Barrel 52 is
provided with diametrically opposite longitudinally extending slots
56 open at their bottom ends for reception therein of diametrically
oppositely disposed outwardly projecting locking lugs 57 carried on
mandrel 50. Each locking lug 57 has an inclined wedge surface 58
wedgingly an lockingly cooperable with an inclined wedge surface 59
provided on a locking bolt 60. Bolt 60 is slidably received within
a transverse part circular housing 61 formed on barrel 52, said
housing 61 extending beyond the outer surface of barrel 52 in a
generally U-shaped cross-sectional configuration to facilitate
gripping of an actuating head 62 on the outer end of bolt 60 by a
claw or other power-operated mechanism of an underwater manipulator
or robot device. Bolt 60 is guided longitudinally and held against
rotation by a longitudinally extending slot 63 therein which
receives a guide pin 64 threaded in housing 61.
Thus when barrel 52 is lowered over mandrel 50 which projects from
the wellhead within conductor guide 24 and locking bolt 60 are in
retracted position as shown in FIG. 6, it will be apparent that the
locking lugs 57 will enter slots 56 and be located adjacent the top
of said slots so that when the locking bolt is pulled outwardly the
inclined wedge surface 59 will move beneath the bottom wedge
surface 58 on the locking lug and wedgingly interlock the barrel 52
with the mandrel 50. In some installations, the wedge surface and
bolt may be arranged so that the bolt is moved inwardly for
locking.
The barrel 52 forms the lower part of a wellhead unit 16 which has
been preassembled before lowering into the water. Barrel 52 may be
connected by well-known clamp means 70 to a wellhead Christmas tree
housing 71 of generally cylindrical elongated form and coaxially
aligned with the mandrel 50 and the production string 41. Wellhead
housing 71 supports production master flow valves 72 and 73, said
valves 72 and 73 being normally open and adapted to be closed when
production control unit 14 is to be recovered. Wellhead unit
housing 71 also supports gas flow valve means 74 of annulus valve
type and which is normally open and adapted to be closed for
recovery of production control unit 14. At the top of housing 71
may be a swabbing valve means 75 which is normally closed and is
adapted to be opened for access to the wellhead housing 71 for
swabbing purposes.
Wellhead unit 16 is also provided with pipe connector means 77 for
connecting production oil lines, gaslines, and control cables to
wellhead unit 16, the opposite ends of said production oil lines,
gaslines and control cables being connected by similar connector
means 78 to production control unit 14. In this example, production
oil flow is connected from wellhead unit 16 to production control
unit 14 through pipe 80 which may be suitably bent so as not to
interfere with access to various valves and connections on the
wellhead and production units by a manipulator device. Gas flow
between the units 16 and 14 is provided by pipe 81 suitably bent
and configured for the same purpose. Control cable 82 connects the
units 16 and 14 in similar manner to provide control of the master
valves 72, 73 and 74 and the shutoff valves 43, 46. The schematic
control and operation of these valves is best shown in FIG. 3 which
will be described hereafter.
Connector means 77 and 78 for connecting the oil flow line 80,
gasline 81 and control cable 82 to wellhead unit 16 and production
control unit 14 may be of the same construction and are described
and claimed in copending application Ser. No. 742,435 owned by a
common assignee. Briefly, connector means 77 (FIG. 7) includes an
externally threaded end portion 100 provided on end 101 of
connecting flow pipe 80, said end portion 101 carrying a
triangularly cross-sectional shaped seal ring 102 adapted to
project beyond the end face of portion 101 for sealing engagement
with an outwardly flared counterbore surface 103 provided at the
open end of passageway 104 in the wellhead housing 71. The internal
end of passageway 104 is connected to the production flow line in
well-known manner (not shown). A generally cylindrical collar 105
may be provided with an end portion 106 having internal threads 107
for threaded engagement with the externally threaded portion 101.
End portion 106 has an end face 107 spaced from the surface of
housing 71 but in relative close proximity thereto so that end face
107 may guide against and reference on the external surface of
housing 71 when the collar 105 is guided into engagement with an
upwardly opening U-slot 108 provided in a wall 109 spaced from the
surface of housing 71 by a pair of spaced projecting tension walls
110. Collar 105 has an intermediate neck portion 111 defined by end
portion 106 and the opposite end portion 112 which may carry
external gear teeth 113 for rotating collar 105. The intermediate
neck portion 111 defines opposed surfaces 114 and 115 which serve
as abutment surfaces against wall 110, said abutment surfaces
having relatively loose tolerance or spacing with respect to wall
109 so as to permit initial axial misalignment of pipe 80 and
collar 105 with respect to the axis of the passageway 104.
When the collar 105 is rotated by engagement of the gear teeth 113
by a suitable tool such as described and claimed in copending
application Ser. No. 779,004, rotation of collar 105 will advance
end portion 101 of the pipe 80 towards the wellhead housing 71 and
any misalignment of the axis of pipe 80 with passageway 104 will be
corrected as the abutment surfaces 114 move into full contact with
the wall 109. In final rotation of collar 105, the seal means 102
is pressed into sealing contact with the sealing counterbore
surfaces 103 on the wellhead housing, and the end portion 106 is in
tight abutment with wall 109 in such a manner that the spaced
projecting walls 110 are subjected to tension forces.
It will be apparent from the arrangement of the connector means 77
and 78 and the manner in which the interconnecting pipe 80, 81 and
cable 83 are bent that a manipulating device mounted on the spaced
rails 22 may be readily positioned for engagement of the
power-operated tool with each of the end portions which carry the
external gears. It should be noted that the axes of the connector
devices lie parallel to the rail members 22 or the path of movement
of the manipulator robot device.
In the application Ser. No. 779,004 disclosing as exemplary tool
for actuating the connector means 77 and 78, the actuator device
comprises a jaw means wherein a lower movable jaw portion is
adapted to be opened to permit engagement of a worm thread carried
by a fixed jaw portion for rotation of the collar 105 when the
lower jaw portion is closed.
Production control unit 14 generally includes valves and flow
control means operable by a suitable power means including electric
motor, pump, accumulator, and hydraulic oil reservoir suitably
contained and enclosed within a top housing means 120 provided on a
readily recoverable and removable top production control portion
121 which may be carried by a lower removable production control
portion 122 supported from the manifold means 26 carried by the
well template assembly. In this example, manifold means 26 includes
an upstanding support column 124 carried by manifold means 26, the
upper portion of support column 124 serving as a mandrel to provide
a readily releasable connection with a lower barrel 125 of the
lower production control unit portion 122. The barrel 125 and
mandrel portion of the support column 124 are releasably
interlocked by wellhead connector means 126 which are constructed
and operable in the same manner as the wellhead connector means
described in FIGS. 4-6, inclusive. The upper end of barrel 125 may
be connected by suitable clamp means 128 to the upper section 129
of the lower production control unit portion 122. Upper section 129
carries suitable wellhead switching valves such as valve means 131
for the oil flow line, 132 for the gasline, and 133 for the oil
test line. Valves 183, 185 and 184 are adapted to be closed for
shutting off flow between the upper portion of the production
control unit and the manifold 26 to isolate a wellhead unit 16 to
permit removal of the upper portion 121 of the unit 14 for repair
and maintenance.
Upper production control portion 121 is releasably connected to the
lower portion 122 by wellhead connector means 135 which includes a
barrel 136 and lock bolt means 137 cooperable with an upper mandrel
portion of the section 129 in the same manner and construction as
described in FIGS. 4-6, inclusive. The production control unit
housing 120 may be connected to the upper portion of the barrel 136
by suitable clamp means 138.
Manifold means 26 as previously mentioned includes oil collection
or gathering line 28, oil test line 27 and a gasline 29, such lines
being connected with each production control unit 14 in the same
manner as described for FIG. 2. It will be apparent that a selected
production control unit of the several supported by the wellhead
template means may be isolated from the manifold means 26 by the
isolation valve 183-185, inclusive, carried in the lower portion
122 of the production control unit 14.
In the production control unit 14 the system of control or
actuating valves there shown is operated by pressure fluid from
accumulator 142 which flows through line 145 to a common manifold
pressure line 146 which supplies pressure fluid to the fluid
actuated valves. Production flow and gas valves in the wellhead
unit 16 may be controlled by a pair of three-way, two-position
valves 148 and 149 which may be solenoid-controlled, spring
return-type valves. Valve 148 is connected by fluid control line
150 to normally open under fluid pressure valve operators 151 and
152 of single-acting, spring return-type connected respectively
with the oil and gas valves 43 and 46. Thus, actuation of valve 148
will cause pressure fluid to control normally open valves 43 and 46
which move into closed position for shutting off flow of oil and
gas from and into the well hole upon pressure decrease and the
spring return means. Valve 149 is connected by pressure line 154 to
single-acting, spring return-type valve operators 155, 156 and 157
which actuate respectively the production master control valves 73
and 72 and the gas valve 74. Thus, suitable operation of valves 148
and 149 may open or close the production flow control valves in the
wellhead unit as well as the gas injection flow. Valves 148 and 149
are solenoid actuated and controlled by suitable electrical means,
acoustical devices or other well-known arrangements for
transmitting control signals.
With production control unit 14, production oil from production
string 41 is transferred through the oil connector line 80 to an
internal flow line indicated at 28a is controlled by a well-known
flow-bean-type valve schematically indicated at 160, said valve
being actuated by a double-acting spring-centered actuator 161
controlled by pressure fluid from lines 162 and 163 at control
valve 164 which may be a four-way, three-position float-centered
solenoid control and spring-centered valve construction. Pressure
fluid for valve 164 is drawn from manifold line 146, and line 163
is connected to manifold pressure fluid return line 165 which
returns pressure fluid to the reservoir 140. The variable flow
restriction valve 160 is of well-known type, such as Willis
flow-bean-type "S."
Similarly, a flow control valve 167 may be provided in the gas
injection line 29a within the production control unit 14, valve 167
being of a type similar to 160 and having a variable flow
restriction or flow bean-type construction. Valve 167 is actuated
by a double-acting, spring-centered operator 168 connected by
pressure fluid line 169 and return line line 170 to a four-way,
three-position float-centered, solenoid-controlled spring-centered
valve means 171 of the same type and arrangement as valve 164.
Each switching valve 131, 132, 133 in the production control unit
14 may be controlled by operators 173, 174, 175, respectively, each
of single-acting, spring return type and connected to pressure
fluid by respective lines 176, 177 and 178, each of said lines
being connected to respective valves 179, 180 and 181. Each of
valves 179, 180 and 181 may be of three-way, two-position solenoid
control, spring return type and may be connected as schematically
indicated to pressure fluid manifold line 146 and to manifold
return line 165.
Mechanical operated isolation valves for production oil line 28,
test line 27 and gasline 29 are schematically indicated at 183, 184
and 185 outside of the production control unit 14.
In operation of the production control unit and wellhead unit, it
will be apparent that the various pressure fluid valves 148, 149,
171, 164, 179, 180 and 181 may be energized or controlled by
suitable electrical means or other control signal means for
pressure fluid actuation of their respective normally open under
pressure operator valves 151, 152, 155, 156, 157 in the wellhead
unit and operator valves 161, 168, 173, 174, 175 in the production
control unit. Thus, during production, flow of oil may be readily
controlled by the variable flow bean restriction valves 161 so that
the rate of flow from each well hole in the well system may be
properly correlated to the flow rate of other well holes in the
system so that a desired continuous uniform flow of oil is produced
by the wellhead system of this invention. It will also be apparent
that when it is desired to test oil from any one of the wellhead
producing units, the switching valves 131 and 133 of each
production control unit may be so actuated as to divert the flow
from line 28a into line 27a for obtaining a sample of the oil from
the well for testing purposes.
The injection of gas into the well may e readily controlled by
actuation of the variable restriction valve 167. Valves 74 and 46
are normally open valves, and of course may be closed in the event
injection of gas is not required.
From the schematic diagram of FIG. 3 and the arrangement of the
wellhead unit 16, production control unit 14 and connector means
82, 80 an 81 between the units, it will be readily apparent that in
the event it is desired to remove the production control unit 14
from the wellhead assembly for maintenance and repair that master
control valves in the wellhead unit 72, 73 and 74 may be closed and
the isolation valves 183, 184 and 185 may be closed so that upon
disconnecting the lines 80, 81 and 82, the upper production control
portion 121 may be readily removed by moving the wellhead connector
bolts at the wellhead connector means 137 by a suitable mechanical
tool means generally described hereinabove. In this instance, means
are provided for removing the pressure fluid from the operators
155, 156 and 157 of the master control valves in the wellhead unit,
such reduction of fluid pressure causing the operators to close
mechanically (spring return) when pressure is removed.
It will also be apparent that the wellhead unit 16 may be
separately and independently removed from the wellhead template
frame construction by closing valves 43 and 46, disconnecting the
lines 80, 81 and moving the wellhead connector bolts 60 into
release position so that the barrel 52 and associated master
control valves 72, 73 and 74 may be recovered for repair and
maintenance of such valves.
Thus in the wellhead system described above, a plurality of
associated sets of wellhead units and production control units may
be separately and independently worked upon without interruption of
the production flow from the other sets of wellhead and production
control units. Each well may be independently controlled and
regulated and tested.
The installation of the above-described wellhead system is
facilitated by the provision of the wellhead template frame
construction already equipped with conductor guide means,
production control units, manifold means and control lines. Thus,
subsea work on the wellhead system is minimized and yet the work
required to install the wellhead system may be readily accomplished
by mechanically actuated tools and connections operable from a
diving bell or other suitable deep sea structure.
It will be understood that various modifications and changes may be
made in the wellhead system and method of installing the system
which come within or embody the spirit of the present
invention.
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