U.S. patent number 3,556,218 [Application Number 04/740,783] was granted by the patent office on 1971-01-19 for underwater production satellite.
This patent grant is currently assigned to Mobil Oil Corporation, A corporation of New York. Invention is credited to James T. Dean, William A. Talley, Jr..
United States Patent |
3,556,218 |
|
January 19, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
UNDERWATER PRODUCTION SATELLITE
Abstract
This specification discloses a method and apparatus for the
production of subaqueous deposits of fluid minerals through a
subsea satellite system. The wells are drilled in a circular
pattern through a template on the marine bottom serving also as
base upon which the satellite body is installed. The production and
control passages of each of the wells are connected to production
equipment within the satellite body by separate connector units,
independently lowered into place from a surface vessel, to form
portions of fluid paths between the passages within the subsea
wellheads and the production equipment within the shell of the
satellite. Such an installation permits production through the
satellite, installed on the template base, after only one of the
wells has been drilled and completed. The produced fluids are
separated and/or metered within the satellite prior to being
transported to storage. Flowline tools are programmed to enter the
various subaqueous wells through the connector units. Hydraulic
circuitry and controls are provided for pumping the tools and
chemicals down through the various wells and for retrieving the
tools. Also disclosed is a hot water well utilized in conjunction
with the heat exchanger within the satellite for warming the
separated-off gases to prevent the formation of hydrates.
Inventors: |
William A. Talley, Jr. (Dallas,
TX), James T. Dean (Dallas, TX) |
Assignee: |
Mobil Oil Corporation, A
corporation of New York (N/A)
|
Family
ID: |
24978049 |
Appl.
No.: |
04/740,783 |
Filed: |
June 27, 1968 |
Current U.S.
Class: |
166/265; 166/366;
166/357; 166/368 |
Current CPC
Class: |
E21B
33/035 (20130101); E21B 43/36 (20130101); E21B
41/08 (20130101); E21B 43/017 (20130101) |
Current International
Class: |
E21B
33/035 (20060101); E21B 33/03 (20060101); E21B
43/36 (20060101); E21B 43/34 (20060101); E21B
43/00 (20060101); E21B 43/017 (20060101); E21b
039/00 (); E21b 033/035 () |
Field of
Search: |
;166/265,267,5.6,265,315,154 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Marvin A. Champion
Assistant Examiner: Richard E. Favreau
Attorney, Agent or Firm: William J. Scherback Frederick E.
Dumoulin Alan G. Paul Donald L. Dickerson Sidney A. Johnson
Claims
1. A system for maintaining a plurality of submerged wells from a
central station comprising: a central station comprising a
submergible, watertight shell and having a first manifold
therewithin; first conduit means providing separate fluid
connections between production passages of each of said plurality
of wells and said first manifold, each of said first conduit means
having parallel fluid flow paths including a first flow path for
production flow and a second flow path for inserting well
maintenance tools into a respective production passage of the
respective well; a first shutoff valve in said first flow path;
means within said shell for inserting a tool into said respective
production passage being connected in series in said second flow
path; and a second shutoff valve in said second flow path, said
second shutoff valve being located between said
2. A system for maintaining a plurality of wells from a central
station, as recited in claim 1, comprising: a source of fluid under
pressure for pumping a well maintenance tool from said
tool-inserting means into said respective production passage
against well pressure; and second conduit means fluidly connecting
said source of fluid under pressure with said second flow path
between said tool-inserting means and said second shutoff
3. A system for maintaining a plurality of wells from a central
station comprising: a central station having a first manifold
therewithin; first conduit means providing separate fluid
connections between production passages of each of said plurality
of wells and said first manifold, each of said first conduit means
having parallel fluid flow paths including a first flow path for
production flow and a second flow path for inserting well
maintenance tools into a respective production passage of the
respective well; a first shutoff valve in said first flow path;
means for inserting a tool into said respective production passage
being connected in series in said second flow path; a second
shutoff valve in said second flow path, said second shutoff valve
being located between said tool-inserting means and said first
manifold; a source of fluid under pressure for pumping a well
maintenance tool from said tool-inserting means into said
respective production passage against well pressure; second conduit
means fluidly connecting said source of fluid under pressure with
said second flow path between said tool-inserting means and said
second shutoff valve; and a pressure-reducing means located in
each
4. A system for maintaining a plurality of wells from a central
station, as recited in claim 3, comprising: a source of fluid under
pressure for pumping a tool from said tool-inserting means into
said respective production passage against well pressure; second
conduit means for connecting said source of fluid under pressure
with said second flow path between said tool-inserting means and
said second shutoff valve; said source of fluid under pressure
being a turbine-pump; a third conduit connected into said first
conduit upstream of said pressure-reducing means in at least one of
said second flow for supplying gas under pressure from said at
least one second flow path to the turbine portion of said
turbine-pump; and means for exhausting waste gas from said turbine
portion
5. A system for maintaining a plurality of wells from a central
station, as recited in claim 4, wherein there is means for
disposing of waste gas that has been used to drive said turbine
portion of said turbine-pump; said waste gas disposal means
including a fourth conduit fluidly connecting the outlet of said
turbine portion of said turbine-pump with a gas manifold downstream
of said pressure-reducing means downstream of said first manifold,
inlets of a plurality of separators connected in parallel to
outlets of said first manifold; gas outlets of said plurality of
separators connected in parallel to said gas manifold; and a gas
outlet line connected to an outlet of said gas manifold for
directing the
6. A system for maintaining a plurality of wells from a central
station, as recited in claim 4, wherein said third conduit means
includes first and second fluid lines and an auxiliary separator,
an inlet of said auxiliary separator being operatively fluidly
connected to an outlet of said first fluid line of said third
conduit means; and said second fluid line of said third conduit
means being connected between a gas outlet of said auxiliary
separator and an inlet to said turbine portion of said turbine
portion of
7. A system for maintaining a plurality of wells from a central
station, as recited in claim 6, wherein said inlet of said
auxiliary separator is fluidly connected to an outlet of a third
manifold by a third fluid line of said third conduit means; and a
first portion of said second fluid line of said third conduit means
is fluidly connected to each of said second flow paths of said
plurality of wells of said central station to inlets of
8. A system for maintaining a plurality of wells from a central
station, as recited in claim 3, comprising: a power-driven pump for
supplying fluid under pressure for pumping a tool from said
tool-inserting means into said respective production passage
against well pressure; and second conduit means for operatively
connecting an outlet of said pump with said second flow path
between said tool-inserting means and said second shutoff valve,
said pressure-reducing means being located between said second
shutoff
9. A system for maintaining a plurality of wells from a central
station, as recited in claim 8, wherein a means for driving said
power-driven pump is
10. A system for maintaining a plurality of wells from a central
station, as recited in claim 8, wherein there is means for
selectively connecting the inlet of said power-driven pump to
either a source of well treating
11. A system for maintaining a plurality of wells from a central
station, as recited in claim 8, wherein there is a three-way
two-position valve, the outlet port of said three-way two-position
valve being connected to the inlet of said power-driven pump; a
first inlet port of said three-way two-position valve being
connected to a source of well treating fluid; and a second inlet
port of said three-way two-position valve being connected
12. A system for maintaining a plurality of wells from a central
station, as recited in claim 8, wherein said second conduit means
comprises: first and second fluid lines and a second manifold; said
first fluid line of said second conduit means being connected
between the outlet of said power-driven pump and an inlet of said
second manifold, a plurality of second fluid lines of said second
conduit means being connected between outlets of said second
manifold and each of said plurality of second flow
13. A system for maintaining a plurality of wells from a central
station, as recited in claim 12 , wherein there is a shutoff valve
in each of said
14. A system for maintaining a plurality of wells from a central
station, as recited in claim 8, wherein there is a source of
substantially clean, dead oil; fifth conduit means for fluidly
connecting said source of
15. A system for maintaining a plurality of wells from a central
station, as recited in claim 14, wherein said source of
substantially clean, dead oil is at least one separator means for
fluidly connecting an inlet of said at least one separator with an
outlet of said first manifold, said separator comprising: a first
outlet for separated-out gas; a second outlet, at the lower end of
said separator, for a separated-out mixture of fluids and solids in
suspension therein; and a third outlet, above said
16. A system for maintaining a plurality of wells from a central
station, as recited in claim 3, wherein there are a plurality of
separators fluidly connected in parallel with said first manifold;
a fourth manifold for collecting produced gas; means for fluidly
connecting gas outlets of said plurality of separators in parallel
with said fourth manifold; a gas outlet line for directing produced
gas from said fourth manifold and out of said central station; a
fifth manifold for collecting produced liquids; means for fluidly
connecting liquids outlets of said plurality of separators in
parallel with said fifth manifold; and a liquids outlet line for
direction produced liquids from said fifth manifold and out of
central
17. A system for maintaining a plurality of wells from a central
station, as recited in claim 16, wherein there is a sixth manifold
for collection clean, dead oil; means for fluidly connecting clean,
dead oil outlets of said plurality of separators, above said
liquids outlets of said respective separators, in parallel with
said sixth manifold for supplying clean, dead oil for pumping well
maintenance tools into the production
18. A system for maintaining a plurality of wells from a central
station, as recited in claim 16, wherein said gas outlet line,
downstream of said fourth manifold, is in fluid connection with a
means for injecting gas
19. A system for maintaining a plurality of wells from a central
station, as recited in claim 18, wherein said at least one
underground formation is an underground formation from which fluids
are being produced through at least one of said wells whereby said
underground formation can be
20. A system for maintaining a plurality of wells from a central
station, as recited in claim 18, wherein said at least one
underground formation is a shallow, low pressure porous formation,
not being produced, whereby
21. A system for maintaining a plurality of wells from a central
station, as recited in claim 3, wherein each of said
pressure-reducing means is a choke whereby the produced fluid is
expanded downstream of each of said chokes; and means for heating
the expanded fluid just downstream of said chokes to hinder the
formation of hydrates and emulsions and to prevent
22. A system for maintaining a plurality of wells from a central
station, as recited in claim 21, wherein the source of heat for
said heating means
23. A system for maintaining a plurality of wells from a central
station, as recited in claim 22, wherein said heating means is an
indirect heat exchanger unit; a first fluid line portion of each of
said first conduit means, upstream of said chokes, for directing
the produced fluid, under pressure, in a first pass through said
indirect heat exchanger unit; and a second fluid line portion of
each of said first conduit means, between the respective choke, and
said first manifold, for directing the produced fluid, now
expanded, in a second pass through said heat exchanger unit whereby
heat is exchanged between said first and said second passes to
24. A system for maintaining a plurality of wells from a central
station, as recited in claim 23, wherein there is a third pass
through said heat exchanger unit fluidly connected at the upstream
end to the single outlet
25. A system for maintaining a plurality of wells from a central
station, as recited in claim 24, wherein the downstream end of said
third pass through said heat exchanger is in fluid connection with
a seventh manifold; and means for fluidly connecting each of a
plurality of
26. A method for maintaining a well in conjunction with a well
maintenance tool that can be pumped into a production passage of
said well, said production passage of said well being a fluid
connection with equipment in a distant production facility through
a first conduit means; said first conduit means having parallel
fluid paths including a first path connected to a first manifold
for production flow and a second path for inserting said well
maintenance tool into a respective production passage of a
respective well; a first shutoff valve in said first flow path; a
tool storage means being connected in series in said second flow
path; a second shutoff valve in said second flow path, said second
shutoff valve being located between said tool storage means and
said first manifold; a source of clean, dead oil for pumping said
well maintenance tool down said respective well production passage
against well pressure; a source of well treating fluid; and means
for selectively fluidly connecting a second conduit means between
said source of clean, dead oil and said second flow path between
said tool storage means and said second shutoff valve, said
selective connecting means is operable to selectively alternately
connect said second conduit to said source of clean, dead oil or to
said source of well treating fluid, including the following steps:
a. shutting said first shutoff valve while leaving said second
shutoff valve closed as it is positioned during production of fluid
from said respective production passage; b. selectively fluidly
connecting said source of well treating fluid with said second
conduit means; c. pumping a prescribed amount of well treating
fluid behind said well maintenance tool; d. selectively fluidly
connecting said source of clean, dead oil with said second flow
path through said second conduit means; and e. pumping clean, dead
oil from said source through said second conduit means whereby a
well maintenance tool in said storage means is pumped out of said
storage means and down through said production passage of said
27. A method for maintaining a well in conjunction with a well
maintenance tool that can be pumped into a production passage of a
well, as recited in claim 26, wherein said well treating fluid is a
paraffin dissolving agent
28. A method for maintaining a well in conjunction with a well
maintenance tool that can be pumped into a production passage of a
well, as recited in claim 26, including the following additional
steps to be performed for the retrieval of said well maintenance
tool from said production passage by the pressure of fluids being
produced through said well: f. shutting off the supply of fluid
under pressure through said second conduit; g. opening said second
shutoff valve so that well fluids are produced through said second
flow path; h. closing said second shutoff valve when said well
maintenance tool has been driven up said production passage and
into said storage means by the produced fluids; and i. opening said
first shutoff valve after said well maintenance tool is again
within said storage means whereby well production continues
thereafter through said first flow path of said first conduit into
said
29. A method for maintaining a well in conjunction with a well
maintenance tool that can be pumped into a production passage of a
well, as recited in claim 26, including the following additional
steps: j. separating the produced fluids into liquid and gaseous
components; k. drawing off clean, dead oil from the upper portion
of said liquid component which could include oil, water, and/or
solids; and l. directing said clean, dead oil to the inlet of a
power-driven pump, the outlet of said power-driven pump being
connected to said second conduit
30. A method for maintaining a well in conjunction with a well
maintenance tool that can be pumped into a production passage of a
well, as recited in claim 26, wherein the means for pumping said
oil is a gas-driven turbine-pump, including the following
additional steps: m. separating the produced fluid into liquid and
gaseous components; n. drawing off at least a portion of the
gaseous component; and o. directing said gaseous component, drawn
off, into the inlet of the
31. A method for maintaining a well in conjunction with a well
maintenance tool that can be pumped into a production passage of a
well, as recited in claim 26, wherein there are a plurality of
wells spaced from said production facility, said production
facility being a satellite station located in the field being
exploited, including the following additional step: p. collecting
the produced fluids from said plurality of wells in a first
32. A method for maintaining a well in conjunction with a well
maintenance tool that can be pumped into production passage of a
well, as recited in claim 31, including the following additional
step: q. choking the flow of produced fluid in the first conduit
means just prior to the collecting of said produced fluids in said
first manifold whereby the pressure in said produced fluids is
reduced in said first manifold.
33. A method for maintaining a well in conjunction with a well
maintenance tool that can be pumped into a production passage of a
well, as recited in claim 32, including the following additional
step: r. heating said produced fluids subsequent to reducing the
pressure thereof by choking the flow of said produced fluids.
Description
This invention relates to a subsea satellite designed to be
interconnected with a group of subaqueous wells having subsea
wellheads so as to control the production therefrom and to provide
ordinary maintenance therefor. More particularly, the invention
relates to a system for inserting one or more types of tools,
and/or chemicals, down through selected wells and for retrieving
the tools upon the completion of the respective function.
Since its inception, the offshore oil and gas industry has used
bottom-supported above-surface platforms as the principal mechanism
for the installation and support of the equipment and services
necessary for the production of the subaqueous mineral deposits. As
the industry has developed over the years, it has extended its
search for offshore minerals from its birthplace, producing oil and
gas in the shallow coastal waters off California and the Gulf of
Mexico into areas where, because of excessive water depth and/or
other local conditions, the bottom-supported platform is not as
economically or technologically feasible.
While theoretically there is no limit to the depth for which a
bottom-supported platform can be designed and installed, experience
to date indicates that platform costs increase almost exponentially
with the increase in water depth. Thus, the presently estimated
costs of a platform to carry the production facilities for a field
in 400 feet of water or more are so high as to indicate that such
an installation cannot be justified economically for any but the
most productive fields. Furthermore, the few bottom-supported
above-surface platforms that have been designed and built for use
in 300 feet or more of water depth have almost invariably suffered
leg failures of one type or another.
A possible solution is to install the production facilities on a
floating platform, as is described in the H. D. Cox Pat. No.
3,111,692, issued Nov. 26, 1963, which can be maintained in
position in a field by either a fixed multipoint mooring system of
anchors and anchor lines, or by a dynamic positioning system. The
above solution involves the expense of continuous maintenance and
surveillance of the locating system as well as the associated
problems and expense of maintaining the multiple flexible lines
connecting wellheads on the marine bottom with the continuously
moving floating production platform, and the potential hazard, of
this system to the hoses, in the event of a failure of the fixed
mooring or dynamic positioning systems.
Another consideration is that, in many areas of the world, local
conditions other than water depth impose critical limitations on
the use of bottom-supported production platforms. In arctic areas,
a bottom-supported platform must be built to withstand the forces
imposed by ice that forms on the water surface during the winter
months of the year, and in many such areas all year long,
Furthermore, any above-water production platform is subject to the
mercy of the wind and waves, especially those occurring during
hurricanes and other violent storms. In the arctic areas these
storms can be exceeded by the forces exerted against the platform
by movement of the thick ice layers that freeze on the surface of
the water. For example, in Cook Inlet, Ak. the local extremely high
tidal movements on the order of 30 feet or more cause very fast
tidal currents in the Inlet, with velocities of up to 8 to 10 miles
an hour or more. These very rapid currents carry with them the
heavy pack ice that forms on the surface of the Inlet, so that it
bears with tremendous force against any fixed structure, such as a
production platform, that should be installed in its path.
In still other areas it is not adverse natural, but manmade,
conditions that restrict the use of bottom-supported above-surface
production platforms. Among such conditions could be listed
official and/or public objection to oil production facilities near
public recreational or residential areas, and the presence of heavy
marine traffic as in harbors, channels, rivers, and other
navigatable bodies of water which make it necessarily advantageous
to install as much of the production equipment beneath the water
surface as possible. For example, the first known use of subsea
wellheads is in Lake Erie where gas is produced from subaqueous
formations beneath the heavily traveled lake.
Therefore, it would appear that where there is extremely deep water
and/or adverse surface conditions, a fully subsea installation
would be the most advisable solution. One method, as is shown by
the J. A. Haeber Pat. No. 3,261,398, issued Jul. 19, 1966, is to
locate the individual pieces of production equipment on the marine
bottom. Such an installation almost necessitates the use of robots
such as shown in the G. D. Johnson Pat. No. 3,099,316, issued Jul.
30, 1963. However, such instrumentalities are expensive and not
without their own limitations and maintenance problems. Another
solution is suggested by the H. L. Shatto, Jr. et al. Pat. No.
3,221,816, issued Dec. 7, 1965, wherein the production equipment
for a plurality of wells is grouped within a satellite chamber
adapted to be raised to the surface for repair and/or
maintenance.
To economically package production equipment used for scheduling,
measuring, separating, and otherwise performing the usual
manipulations on producing oil and gas wells, it is believed to be
necessary to enclose the equipment within a pressure-resistant
satellite shell within which can be maintained a breathable
atmosphere permitting the equipment inside to be serviced and/or
maintained by personnel, not encumbered with diving suits. Single
well chambers, most being removable, have been proposed and are
exemplified by the J. D. Watts et al. Pat. No. 3,202,216, issued
Aug. 24, 1965. The most feasible system should include a subsea
satellite having therewithin production equipment servicing a
number of wells and capable of maintaining life sustaining
conditions therewithin.
No feasible system has been presented to date for economically
maintaining the several serviced wells in operating condition
during production. This would require the periodic passing through
of tools for cutting paraffin, setting chokes, removing sand, and
other operations normally done with wirelines in a land or
platform-supported well. A necessary part of such a maintenance
system is means for detecting a malfunction in a well or in simpler
installations, for instance, where frequent paraffin cutting is
necessary, a timed sequence can be used. Apparatus must be provided
for moving a single tool selectively through one of a number of
wells and for storing one tool when one performing a different
function is to be directed into a well.
While wireline tools have been used for many years to maintain
wells and through-the-flowline (TFL) tools are known and have been
used at least experimentally, a complete automatic system for
maintaining several wells as a group is not available. The P. R.
McStravick et al. Pat. No. 3,022,822 discloses a system for pumping
a wireline tool down through a single subsea wellhead from a nearby
above-surface location, but is not concerned with the selection of
a particular tool, the timing of the operation, or the storage of
the tool for a second operation. The F. H. Culver et al. Pat. No.
3,101,118 discloses a subsea wellhead to be utilized in conjunction
with a wireline tool which is guided in and out of the wellhead
through wide branch conduits thereof. The S. A. Bergman et al. Pat.
Nos. 3,063,079 and 3,063,080 disclose launching devices for
inserting pipe scraping tools or pigs into a pipeline while the K.
D. Savage Pat. No. 2,856,884 discloses a system for storing a pig
in an adjacent pipe when it is not being used in the pipeline.
In accordance with this invention, fluid produced from a plurality
of wells, through subsea wellheads, is processed within a satellite
station prior to being transported to storage. The produced fluid
from the plurality of wells is combined into a single stream within
the satellite station. The fluid stream is choked to reduce the
wellhead pressure to that necessary to drive the fluid up to a
surface installation. The fluid is then directed into a plurality
of gravity separators connected in parallel. The gas taken off from
the plurality separators is recombined and the main portion thereof
directed to storage, utilized in a gas lift operation, or disposed
of by flowing or being injected into shallow sand formations. A
minor portion of the gas may be utilized to drive a turbine of a
turbine-pump for pressuring up a TFL (through-the-flowline) system.
The liquids, including oil and gas and sediment, are directed
through the lower ends of each of the separators, the liquids being
recombined and transmitted to storage. A clean oil pickup from
within at least one of the separators directed oil from a point
above the sediment level of the respective separator to the pump
portion of the TFL system. In a storage tank forming a lower
portion of the satellite body, open to the sea at the lower end
thereof, a well treating fluid may be stored. Alternatively, the
well treating fluid can be stored in and supplied from a surface
vessel moored over the site. Wherever the source of treating fluid,
it is in fluid communication with a first inlet of the turbine-pump
through a three-way two-position valve, the second inlet thereof
being connected to the clean oil source whereby a prescribed amount
of treating fluid followed by clean oil can be pumped into the TFL
circuitry behind a tool whereby the TFL tool is forced through the
subsea wellhead and down into the respective well to perform a
desired function. In place of the turbine-pump, an electrically
driven pump may be used. In this case, the clean oil pickup line is
dispensed with. Where a medium or high GOR (gas-to-oil ratio) is
encountered, a heat exchanger unit is necessary to prevent hydrate
formation, minimize excessive paraffin deposition, and restrict
emulsion formation. For a medium GOR, the unit may consist of only
passing the fluid prior to expansion in close conjunction with the
fluid after expansion within an insulated area. Where there is a
high GOR, an outside heat source is necessary.
FIG. 1 is a pictorial view of a subsea production system in
accordance with the present invention;
FIG. 2 is a partially broken away enlarged view of one of the
satellite stations shown in FIG. 1, illustrating the arrangement of
the equipment therewithin;
FIG. 3 is a schematic representation of a heat exchange system to
be utilized within the satellite station also, but shown in less
detail in FIG. 2;
FIG. 4 is a schematic diagram of the basic circuitry required to
produce a plurality of oil and gas wells within a satellite
station;
FIG. 5 is a schematic diagram of a modified TFL Fluid Supply
System;
FIG. 6 is a schematic diagram of a modified production system for
producing a field having a high gas-oil ratio;
FIG. 7 is a schematic diagram of a modified production system for
producing a field having a medium gas-oil ratio; and
FIG. 8 is a schematic diagram of a modified satellite station
configuration for allowing the satellite body to be installed on a
base template of a satellite station prior to the completion of any
of the wells through the base template.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now looking to FIG. 1, a subsea system for producing fluid
minerals, in particular gas and oil, from a subaqueous field by a
plurality of subsea wellheads is illustrated. A plurality of subsea
production satellite stations, generally designated 10, are spaced
across a marine bottom 12, each satellite station 10 comprising a
satellite body 15 centrally positioned within a circular group of
closely spaced subsea wellheads 14. The produced fluids from the
subaqueous wells are directed through encircling subsea wellheads
14 into the satellite body 15 of the respective satellite station
10. The fluids being produced from the subsea wellheads 14 of each
circular group are combined within the respective enclosed
satellite body 15 and a first stage of separation (gravity) takes
place. At least the liquid portion is then directed to a circular
manifold 16 atop a central bottom-mounted storage tank 17 through a
shipping line 18, one shipping line 18 extending from each
satellite station 10.
A floating master station 20, having power generating and final
stage separation equipment thereon, as well as being fitted out
with off-loading apparatus, is in fluid and electrical
communication with the bottom-supported storage tank 17 through a
tensioned tether pipe 22 extending from the storage tank 17 to a
point just beneath the turbulent surface zone of the body of water
and fixed at this point to a large subsurface buoy 24. A flexible
conduit 26, containing a plurality of electrical and fluid flow
paths, extends from the upper end of the tensioned tether pipe 22
to the floating master station 20. The produced liquid, collected
in the circular manifold 16, is directed to the master station
through a main shipping line 27 supported along the length of the
tether pipe 22, and a fluid line forming a portion of the flexible
conduit 26. The produced liquid passes through the final stage
separation equipment on the master station 20 where the pressure is
normalized and dissolved gases are removed. The dead liquid is then
transported to storage within the storage tank 17 through a line of
the flexible conduit 26 connected to an axial passage in the
interior of the tether pipe 22.
In the upper left-hand corner of FIG. 1 is illustrated the drilling
of a well through a satellite base template, generally designated
28, which has been previously installed on a marine bottom along
with a shipping line 18' for connecting a satellite station, when
completed in conjunction with the template 28, with the storage
tank 17. A drill string 30 is suspended from above the surface from
a semisubmersible drilling vessel 32 and extends through a blowout
preventer stack 33 mounted on one of a plurality of upstanding well
conductor pipes 34 forming a portion of the template 28.
Illustrated in the lower portion of FIG. 1 is a manned submersible
work vehicle, generally designated 36, of a type to be employed at
assist in the subsea operations and for the dry transfer of
personnel to the satellite station 10. The submersible work vehicle
36 has a pair of articulated arms 38 and 40 carrying a socket
wrench 42 and a vise grip tool 44, respectively. The submersible
work vehicle 36 is further equipped with a pivotable positioning
motor 46 on each side (one shown) to assist in locating the
submersible work vehicle 36 adjacent a satellite station 10 firstly
when subsea operations are to be performed during the drilling
operations and the installation of the satellite body 15
therewithin, and at later times during maintenance and workover
operations. A lower port 48 of the submersible work vehicle 36 is
connected with a rear compartment (not shown) within the shell
thereof to permit a diver to be released at an installation site if
one should be needed. The rear compartment is isolated from the
pilot's compartment, seen through the front view plate 50, so that
a diver after exposure to deep water can be kept in compression in
the rear compartment while the front compartment is maintained at
atmospheric conditions. This general type of submersible work
vehicle is well known in the art and specific vehicles of this type
are more fully described in the application Ser. No. 649,959, filed
Jun. 29, 2967, of Warren B. Brooks, Charles Ovid Baker, and Eugene
L. Jones, and the references cited therein.
Now looking at FIG. 2, the interior of the satellite body 15, as
well as the satellite base template 28, are illustrated in more
detail. The internal equipment comprises that necessary for a high
gas-oil ratio, high pressure field. The base template 28 comprises
an outer ring 51 to which are rigidly connected the plurality of
upstanding vertical well conductor pipes 34 through which
subaqueous wells have been drilled. As shown, a dual completion
wellhead 14 is mounted on the upper end of each of the well
conductor pipes 34 in completing each of the respective subaqueous
wells. The satellite body 15 is installed after the completion of
all of the wells drilled through the respective base template 28.
The satellite body 15 is shown to be cradled in a plurality of
radially extending spaced arms 41 fixed to the base template 28.
Threaded detent rods 43 extend through each of the arms 41 and
through the shell of the satellite body 15 into receivers 45 fixed
to the inner wall of the shell. The detent rods can be screwed into
and out of engagement with the receivers by means of the socket
wrench 42 of the submersible work vehicle 36. A hex nut 53,
terminating in a conical guide, is affixed to the outer end of each
detent rod 43. Support frames 47, having pillow boxes 49 in which
the detent rods 43 are journaled, allow the use of long detent rods
43 extending radially out beyond the well conductor pipes 34.
A water well 52 is shown as having been drilled through the center
of the base template 28 and is necessarily completed prior to the
installation of the satellite body 15. After all of the wells,
including the water well 52, have been completed, the satellite
body 15 is lowered into place and is leveled and locked into the
base template 28 in any suitable manner. There would be no reason
why one water well could not be drilled through one of the well
conductor pipes 34 on the ring 51 of the base template 28, if this
should prove more convenient. The only disadvantage would be the
elimination of one possible producing well. The W. F. Manning
patent applications Ser. Nos. 663,799 and 663,798 entitled Subsea
Satellite Foundation Unit and Method for Installing a Satellite
Body Within said Foundation Unit, and Subsea Satellite Foundation
Unit and Method for Installing a Satellite Body Therewithin,
respectively, disclose alternate leveling and locking means as well
as means for registering the installed satellite with respect to
encircling wellheads.
The water well 52 is designed to provide a heat source for a heat
exchanger unit (to be discussed below) to warm the produced fluids
after a pressure cut has been taken. The well water may also be
directed through radiators in the portions of the satellite body 15
in which personnel are present to raise the interior temperature of
that portion the satellite body 15 above the ambient temperature at
the marine bottom. In deep water the temperature at the marine
bottom is in the range of 35.degree. F. to 45.degree. F., too cold
for a man to work for long periods unless he is heavily
clothed.
Each of the submerged dual completion wellheads 14 has a pair of
upstanding tubing nipples (not shown), each being in fluid
communication with a producing zone. Each of the pairs of tubing
nipples is adapted to telescope into complementary passages of
stabover connector unit, generally designated 54, comprising a pair
of downwardly curving tubing sections 56 extending radially outward
from within the shell of satellite body 15 and terminating in
vertical lubricator sections 58. By means of the stabover connector
units 54, the production and control passages extending through the
subaqueous wells are connected to manifolds within the satellite
body 15 for the combining of the produced fluids through the
satellite body 15 and/or for the injection of lift gas, or other
fluids utilized in secondary recovery procedures, from the
satellite body 15, to all or selected ones of the subsqueous wells.
As shown in the embodiment of FIG. 2, the stabover connector units
54 are permanently fixed with respect to the satellite body 15.
Therefore, the satellite body 15 must be radially positioned quite
precisely so that the stabover connector units 54 can register with
and telescope over the upstanding tubing nipples of the respective
wellheads 14.
An escape hatch 60 is formed within the upper end of the satellite
body 15 to permit the entry of an operator 62 from a diving bell or
travel chamber, as shown in the Townsend application Ser. No.
521,745, filed Jan. 19, 1966, or a submersible work vehicle 38. The
upper portion of the interior of the satellite body 15, within
which the operator 62 is shown sitting at a panel 64, comprises a
control section, generally designated 66, from which various
operations, not normally programmed, may be controlled and from
which stored information can be retrieved. Below the control
section 66 is a production section, generally designated 68,
containing the various equipment necessary to separate and meter
the produced fluids as well as to pump treating fluids and tools
through the various wells.
Beneath the floor of the production section 68 is a treating fluid
storage section, generally designated 70. The treating fluid
storage section 70 generally comprises an open-bottomed tank
defined by the floor 71 of the production section 68 and the outer,
generally cylindrical shell of the satellite body 15. The storage
section 70 can be partitioned to permit the storage of two or more
discrete well treating fluids needed in one or more operations.
Although some plumbing extends through the storage section 70, it
is substantially uncluttered to permit the storage of a large
quantity of well treating fluid.
Centrally located, within the production section 68, is a
cylindrical heat exchanger unit 74. Equiangularly spaced around the
heat exchanger unit 74 are a plurality of spherical separators 72.
The produced fluids normally flow through the shell of the
satellite body 15 by way of the tubing section 56 of the connector
units 54. From a tubing section 56 the fluid is directed by a
branch conduit 76 through an expansion valve (shown in FIG. 3 and
to be discussed with respect thereto) into an upper heat exchanger
manifold 78 located within the upper end of an insulated jacket 79
of the heat exchanger unit 74. Fluids, exiting from the manifold
78, flow down through a central pipe 80, leaving the heat exchanger
unit 74 near the lower end thereof by means of conduits 82 (one
shown) which lead the produced fluids into the individual
separators 72.
The separators 72 in the satellite station 10 are of the gravity
type to permit the separation of the gas from the oil without a
substantial temperature deep in the separators, avoiding hydrate
and paraffin deposition problems therewithin. A loss of 7.degree.
F. to 8.degree. F. would be normal with such equipment. With a
one-minute retention time within the separator, all of the free gas
will be removed, only the gas, dissolved in the liquid at the
separator pressure, remaining for the secondary, or final,
separation stage. While the separators planned for this
installation have no water knockout feature, provision for removal
of water from the oil could be provided if it was desirable at this
stage of production. The pressure at which the separators 72 are
designed to function may be governed by the depth at which the
satellite station 10 is located since it is desirable to have
sufficient pressure to lift the oil from the marine bottom to the
master station 20 on the surface. In very deep water the produced
oil may have to be lifted, at least in part, by power-driven pumps.
Where the satellite is connecting into a truck pipeline, rather
than being transported away by tanker, the output pressure of the
separators would be governed by the line pressure in the pipeline.
Where the wells are producing with a wellhead pressure of, for
example, 1,500 p.s.i. and the satellite station 10 is located in
2,000 feet of water, a 900-pound pressure drop will be taken, prior
to introducing the produced fluid into the separators 72, to obtain
a pressure of approximately 600 hundred p.s.i., which would be that
necessary to drive the oil from the marine bottom to the surface.
Taking a pressure drop of 200 p.s.i. lowers the temperature of the
of the produced fluids by more than 50.degree. F. When considering
a 10,000-foot well in which the produced fluids at the wellhead
would be at from 150.degree. F. to 170.degree. F., at 50.degree. F.
the resultant temperature would be well within the formation
temperature of hydrates and paraffins.
The heat exchanger unit 74, as shown more fully in FIG. 3, is
located in the process fluid circuitry between expansion chokes 84,
one located in each of the branch conduits 76, and the separators
72, providing a regulated flow of warm water as a heat source to
increase the temperature of the mixed oil and gas on the downstream
side of the choke 84 where a pressure cut has been taken, to
prevent hydrate formation, minimize excessive paraffin deposition
in the equipment, and restrict emulsion formation. The heat
exchanger unit 74 depends upon well water obtained from the
previously mentioned water well 52 (shown only in FIG. 2). The
water is produced through a normal type of oil well completion and
then flows through a variable choke 86 that regulates the flow and
downstream pressure. In an example, using a 10,000-foot water well,
the water at the upper end of the heat exchanger will also be in
the range of 150.degree. F. to 170.degree. F. The water from the
well 52 is directed upward through a conduit 88, entering the
insulated cylindrical jacket at 79 of the heat exchanger unit 74,
through the upper end thereof. The water travels down through the
interior of the heat exchanger jacket 79, emerging from the lower
end thereof in outlet line 90 from which the water is dumped into
the sea. As the cold produced fluid passes into the manifold 78
within the upper end of the heat exchanger unit 74, after passing
through the expansion choke 84 and a one-way valve 92, the fluid
comes into indirect contact with the warmer water flowing around
the manifold 78. From the manifold 78, the produced fluid flows
through a helical coil 94 extending axially through the heat
exchanger unit 74 and into a heat exchanger manifold (not shown) in
the lower end thereof, and then out of the jacket 79 through
conduits 82, each connected between one of the separators 72 and
the lower heat exchanger manifold. A temperature sensor 96 is
installed in at least one of the outlet lines 82 to act as a flow
indicator and monitor mechanism to control the increase or decrease
of the water flowing into the heat exchanger unit 74. By increasing
or decreasing the size of the choke 80, the water flow is regulated
to maintain the required temperature of the produced fluids
entering the separators 72 (FIG. 2). Such a system also acts as a
resource conservation in that large use of produced oil and/or gas
to fire such heater equipment as would be otherwise needed is not
required.
Looking back to FIG. 2, the liquids leave the separators 72 through
respective liquid outlet lines 98, connecting the separators 72
with liquid output manifold 100 centrally positioned around the
lower end of the heat exchanger unit 74. The combined produced
liquid from the plurality of separators 72 is directed from the
manifold 100 through a main oil outlet line 102 which is connected
to the input end of a respective shipping line 18.
The liquid is removed, at the lower end of each of the separators
72, by the respective line 98 so as to also drain off all the
water, entrained sand, and other impurities with the oil. These
impurities might otherwise impede the action of the separator 72
and cause a premature malfunction thereof. A shutoff valve 104 in
each of the liquid outlet lines 98 is controlled in conjunction
with a float (not shown) within each of the separators 72, to
regulate the levels of the liquid within the separators 72. As
shown, a mechanical linkage is utilized between the float and the
valve 104. One of the electromechanical systems, well known in the
art, could be substituted for the mechanical linkage. A clean oil
line 108 is connected at a first end thereof into at least one of
the separators 72, above the lower end thereof, to pick up oil from
above the sediment level and below the low level of the liquid to
provide substantially clean oil (with dissolved gas) for pumping a
tool into and down through a selected well. Line 108, at the other
end thereof, is connected to a first inlet of three-way
two-position valve 110, the outlet of which is connected to the
inlet of a gas-driven turbine-pump 112 to provide the clean oil
under pressure to the TFL system. A second inlet of the three-way
two-position valve 110 is also connected to a line 114 having a
pickup head 116 in the fluid storage section 70 of the satellite
body 15 to provide a source of treating fluid for the turbine-pump
112. Gas under pressure, for driving the turbine portion of the
turbine-pump 112, is provided through a turbine gas supply line 118
extending from an auxiliary turbine (not shown in this view) which
is supplied with produced fluid tapped off, through lines 119,
upstream of the chokes 84. The clean oil under pressure from the
pump portion of the turbine-pump 112 is fed into a manifold (not
shown in this view). From this last-mentioned manifold, the oil is
pumped out, being selectively directed into one or more pressure
lines 122, each pressure line 122 being connected into a bypass
conduit section 124 just behind a TFL tool 126 stored therein. Each
bypass conduit 124 is directly connected to a curved tubing portion
56 of a connector unit 54 for pumping the TFL tool 126 therein into
the connected wellhead 14 and down a passage of the respective
well. The separated-out gas, leaving a separator 72 through an
upper pipe or gas outlet line 120, is combined with the
separated-out gas from the other separators 72 in a ring manifold
unit 128 encircling the insulated jacket 79 of the heat exchanger
unit 74.
The separated-out gas can be, in various instances, utilized in
production procedures, stored for eventual transportation to shore,
or disposed of at the site of the offshore production field. A main
outlet line 130, from the ring manifold 128, is shown directing the
gas out of the satellite station 10 for disposal through one or
more distant gas disposal wells (not shown) where the gas will be
injected into shallow sands underlying the marine bottom. A safety
regulator valve 132 is connected in the main outlet line 130 to
allow gas to be bled off through a flare line 134 to the master
floating station 20, if the pressure in the main outlet line 130
should rise above a predetermined value. If the gas obtained in the
primary stage of separation is to be either disposed of by flaring
or is to be stored for future transportion-to-shore facilities, it
is conducted to the master station 20 by shipping line (not shown),
as described with respect to the produced oil. At the master
station 20, the gas obtained from the primary stage of separation
is combined with the gas obtained from the secondary or final stage
of separation on the master station 20. If the gas is to be flared,
a flare stack is erected above the master station 20. If the gas is
to be stored, it is first compressed at the master station 20 and
then is pumped down to a portion of the storage tank 17 or to a
separate storage tank (not shown) nearby. As noted above, the gas
from the primary separation stage may also be utilized in
production procedures, the most common of these procedures being
the utilization of the gas under pressure to provide lift pressure
in the producing formations. A gas injection well for this purpose
may be one of the wells drilled through the ring 51 of the template
28, in which case a separated-out gas is fed into the wellhead 14
through a respective one of the curved tubing sections 56 of a
stabover connector unit 54, or the injection well may be located at
a distance from the satellite station 10, in which case an
interconnecting flowline having a pressure regulator valve and a
flare line, as described above with respect to injecting the gas
into shallow sand formations, will be utilized.
FIG. 4 illustrates, in schematic form, a complete system, with the
exception of a storage means, for the production of a low gas-oil
ratio low pressure field. The fluid is produced in the portion of
the system designated as Well and Wellhead Equipment at the TD
(total depth) 136 of a representative well, generally designated
138. In the well 138 is a storm choke 140 placed at approximately a
3,000-foot thousand-foot depth, below the normal lower limit of
paraffin deposition, for safety purposes. Quarter-turned manually
operated valves 142 are mounted on the wellhead 14 outside the
satellite body 15 where they are easily accessible for operation by
a man, robot, or a manned craft such as the underwater submersible
work vehicle 36 illustrated in FIG. 1. In some instances, it may be
desirable to utilize remotely actuatable valves in place of the
manually operated valves 142. A high-low safety valve 144, also
mounted on the wellhead 14 outside the satellite body 15, will
automatically close should the pressure in the well 138 exceed a
specified high pressure or drop below a specified low pressure.
From the upper end of the wellhead 14, the fluid is directed
through connector unit 54 to the portion of the wellhead equipment
within the satellite body 15 where one or more TFL tools are stored
in a storage chamber, designated by block 146. (A TFL storage
device and a paraffin cutting tool, designed to be stored
therewithin, are fully described in the patent application Ser. No.
579,571 of James T. Dean, entitled Storage System for TFL Tools,
filed Sept. 15, 1966, now U.S. Pat. No. 3,396,789. In FIG. 3 of the
Dean patent, the incorporation of the described storage device in a
fluid circuit for automatically maintaining a subsea well is
shown.) The TFL storage chamber 146 is located in the previously
described bypass conduit section 124, as is a TFL tool control
valve 148, which remains closed except during TFL maintenance
and/or testing. The branch conduit 76 contains a pressure indicator
150, an orifice meter 152, and a production wing valve 154. The
production wing valve 154 is normally open while the well 138 is
producing and closed during TFL operations. The branch conduit 76,
through which the produced fluid generally flows, provides a path
around the TFL storage chamber 146 and the closed control valve
148. When the well 138 is producing, the fluids flow from TD point
136, up through the storm choke 140, and the series of valves 142
and 144, of the wellhead 14, into the branch conduit 76. The
pressure and flow rate of the fluid at the wellhead 14 are
monitored at all times by the pressure indicator 150 and the
orifice meter 152, respectively, and representative signals are
transmitted to, and recorded within, the control section 66 of the
satellite station 10.
The produced fluid flowing through the branch conduit 76, past the
interconnection with the bypass conduit section 124, leaves the
portion of the system designated in the schematic diagram as
Wellhead and Wellhead Equipment and enters the portion designated
Production System through a rotary variable choke 156. As the fluid
passes through the variable choke 156, the pressure is lowered from
that at the wellhead 14 to a pressure just above that necessary to
drive the fluid from the marine bottom to the surface. From the
rotary choke 156, the produced fluid is directed through a check
valve 157 into a collector manifold 158. Branch conduits 76', each
having a check valve 157', also shown as leading into the collector
manifold 158, are connected to the wellhead equipment of the
various wells encircling the satellite station 10. A pressure
sensor 160 is mounted in the collector manifold 158 to monitor the
pressure therewithin, a signal representative of which is
transmitted to and recorded within the control portion of the
satellite station 10. The rotary variable choke 156 is controlled
in response to the pressures indicated by the pressure sensors 150
and 160. Three gravity separators 72 are connected, in parallel, to
the collector manifold 158 through inlet lines 162, each having a
shutoff valve 163 therewithin. The liquids, including oil and
water, exit for the most part through lines 98 which empty into a
liquid collector manifold 164. This manifold corresponds to the
circular manifold 100 shown in FIG. 3. From the liquid collector
manifold 164, the oil exits through the outlet line 102 and is
transferred to storage through shipping line 18 after passing
through a flow meter 166. A clean oil outlet line 108, as
previously discussed, extends from a point within each of the
separators 72, from where substantially clean pure oil can be
obtained, to a manifold 175, which empties in turn into the
upstream end of a line 174 connected at its downstream end to an
inlet port of a three-way two-position valve 180 in the TFL Fluid
Supply System. The gas accumulating in the separators 72 passes out
through a high liquid shutoff valve 168 located in the upper end of
each of the separators 72, into a gas outlet line 120, which
empties into a gas collector manifold 170. The major portion of the
gas leaves the manifold 170 through the main gas outlet line 130,
passing through an orifice meter 172, and is transferred to storage
or disposal means. By disposal means is meant "flaring" or "shallow
sand injecting" as previously discussed. The fluid pressure supply
line 119 is connected between the bypass conduit 124, at one end
thereof, and a manifold 159 at the other end. Lines 119' connect
the bypass conduits of the other wells, which flow through the
satellite station 10, with the manifold 159. The inlet of an
auxiliary separator 161, where only a small pressure cut is taken,
is in fluid connection with the manifold 159 through a high
pressure line 165. The turbine gas supply line 118 is connected
between the gas outlet of the auxiliary separator 161 and the inlet
of the turbine of the turbine-pump 112 of the TFL Fluid Supply
System to supply high pressure gas to the pump portion of the
turbine-pump 112. The pressure-reduced gas, from the gas discharge,
or outlet, of the pump portion of the turbine-pump 112, is directed
through a line 167 into the gas collector manifold 170. The liquids
separated out in the auxiliary separator 161 are directed through
line 169 into the liquid collector manifold 164. The purpose of the
turbine-pump 112 is discussed below. If one of the separators 72
becomes plugged, the liquid will fill that separator and force the
respective valve 168 to close. With this possibility in mind, the
separators 72 are designed so that any two are all that are
required to process the total amount of fluid passing through the
satellite station 10. With the same rate of flow of gas through the
orifice meter 172, and liquid through the flow meter 166, a signal
warning of an increase in pressure will be transmitted to the
control portion 66 of the satellite station 10 from the sensor 160
in the manifold 158, indicating that there is a problem.
Furthermore, the closing of a valve 168 can be made to actuate an
electric switch, which in turn will provide a signal indicating
which separator is malfunctioning. The production stream through
the plugged separator 72 would then be cut off by closing the
respective shutoff valve 163 so that the respective separator 72
can be serviced by personnel within the satellite station 10.
The portion of the schematic diagram designated as the TFL Fluid
Supply System contains a fluid storage means 178, which corresponds
to the open-bottomed fluid storage section 70 of the satellite
station 10 as shown in FIG. 2. The storage means 178 is connected
to a first inlet port of the three-way two-position valve 180
through a line 190 having a salt water sensor 188 therein to
provide a signal in the control section of the satellite station 10
indicating that the storage means 178 is empty of treating fluid
and now contains only salt water. The other inlet port of the
three-way two-position valve 180, as previously discussed, is
connected to a source of clean oil through the line 174 extending
from the manifold 175 in the Production System portion of the
schematic diagram. The outlet of the three-way two-position valve
180 is operatively connected to the inlet of the pump portion of
the turbine-pump 112, the outlet of the pump portion of the
turbine-pump 112 being connected to an inlet of a manifold 182
through a conduit 184. The power for driving the pump portion of
the turbine-pump 112 is provided by gas under pressure obtained
through the line 118 from the auxiliary separator 161, which is fed
with produced fluid at wellhead pressure from the Well and Wellhead
Equipment portion of the system as previously outlined. By opening
and closing a valve 176 in the line 118, the operation of the
turbine-pump 112 may be controlled. From the manifold 182 the clean
oil and/or the treating fluid, under pressure, is pumped through
one or more of the outlet lines 192 at a time, each of the outlet
lines 192 having a check valve 194 and a selectively actuated
cutoff valve 196 therein from which the fluid is directed through
the respective line 122 into the Well and Wellhead Equipment
portion of the schematic diagram where it is directed into the
bypass conduit 124 between the TFL tool storage chamber 146 and the
shutoff valve 148. Outlet lines 192', each having a one-way check
valve 194' and a shutoff valve 196' therein, are connected to the
bypass conduits of the Well and Wellhead Equipment portions of the
other wells (not shown) producing through the respective satellite
station 10.
To commence a TFL maintenance and/or testing procedure, valves 148
and 154 in the Well and Wellhead Equipment portion would both be
closed. The shutoff valve 176, in the TFL Fluid Supply System,
connected to the input of the turbine-pump 112 would be open to
activate the turbine portion. For paraffin removal, for instance, a
paraffin solvent and corrosion inhibitor stored in the storage
means 178 would first be drawn into the input of the pump section
of the turbine-pump 112 by the proper positioning of the valve 180.
After pumping approximately one barrel of treating fluid through
the valve 180, the position of the valve would be changed so that
the oil from line 174 would then be supplied to the pump portion of
the turbine-pump 112. One or more of the valves 196, 196' would be
open to permit the fluid driven by the turbine-pump 112 to exit
from the header 182 through a line 122 to apply fluid pressure in
the section of the bypass conduit 124, of the Well and Wellhead
Equipment portion, between the valve 148 and the storage means 146.
With the valve 148 closed, the fluid driven through line 122 into
the bypass conduit 124, behind the storage means 146, will cause a
paraffin cutting tool 126 positioned within the storage means 146
to be propelled down through the curved tubing section 56 of the
connector unit 54 and down through the wellhead 14 of the
respective well 138. The piston section of the tool 126 is not
completely sealed within the tubing of the well 138 in which it
moves so that by the time the tool is down in the well, at the
lower end of the paraffin deposition zone, all of the treating
fluid is in the well ahead of the tool. When the tool 126 reaches
the end of its travel, above the storm choke 140, the valve 176, in
the TFL Fluid Supply System portion, controlling the turbine-pump
112, would be shut causing the turbine-pump 112 to cease operation.
The shutoff valve 148 in the bypass conduit 124 is then opened
causing the TFL tool 126 to be returned up the well 138 by the
fluid being produced, which now is directed into the downstream
portion of the branch conduit 76 through the bypass conduit 124.
When the TFL tool 126 has reentered the storage chamber 146, an
indication of this condition will be given in the control section
66. A switching means for providing this function is shown in the
Dean patent U.S. Pat. No. 3,396,789 discussed above. At this time,
the valve 148, in the bypass conduit 124, will be shut and the
valve 154, in the branch conduit 76, will be reopened, returning
the well to production through the branch conduit 76. All of the
previously described steps can be sequentially performed by an
operator in the control section 66 of the satellite station 10, by
remote control from the floating master station 20, or by a
programmed computer, or by a combination of the aforementioned
methods.
FIG. 5 illustrates a modification in which an electric motor 198 is
utilized for driving a pump 200. With the substitution of the
electric motor 198 and the pump 200 for the turbine-pump 112 (shown
in FIG. 4), the gas line 118 is eliminated and the only exit line
from the manifold 170 is the line 130. The remainder of the TFL
Fluid Supply System (shown in FIG. 5) is identical to that shown in
FIG. 4, therefore being a storage means 178' connected to one inlet
of a three-way two-position valve 180' through a line 190' having a
salt water sensor 188' therein. The other inlet of the three-way
two-position valve 180' is connected to the line 174 as shown in
FIG. 4 which is connected at the other end thereof to a clean oil
source in the separators 72. The outlet of the three-way
two-position valve 180' is operatively connected to the inlet of
the pump 200. The outlet of the pump 200 is in turn connected,
through the line 184, to the header 182, as shown in FIG. 4. The
identical procedure would be followed with the exception that
electrical power would be used to operate the electric motor 198 to
drive the pump 200.
FIG. 6 shows the modified Production System to be used with the
typical high gas-oil ratio high pressure well. This modified
Production System is utilized with the Well and Wellhead Equipment
portion and TFL Fluid Supply System portion of the schematic
diagram of FIG. 4. As the produced fluid is directed from the
branch conduit 76 through a variable choke 156' and a check valve
157', it is collected in a primary manifold 202 (generally similar
to the manifold 78 shown in FIG. 2). The produced fluid in the
manifold 202, having a high gas content, is now quite cold due to
expansion in the choke 156'. This cold fluid passes out of the
manifold 202 through a line 204 extending through a heat exchanger
unit 206 (corresponding to the heat exchanger unit 74 of FIG. 2).
The fluid, warmed up in the heat exchanger unit 206, enters a
secondary manifold 208 from which it is directed into three
separators 72'. A pressure sensor 209 and a temperature probe 238
are located in the secondary manifold 208. From the separators 72'
the major part of the produced liquid is collected in the manifold
164' after which it is removed through a line 102' having a flow
meter 166' therein, the outlet of the flow meter 166' being
connected to the inlet of a shipping line 18 connecting the
satellite station 10 with a distant storage facility. Again, clean
oil is picked up by lines 108' and is directed through line 174' to
the clean oil supply inlet of the three-way two-position valve, as
shown in FIG. 4. The gas exiting from the separators 72', through
lines 120', is collected in the manifold 170' from which it is, in
the main, transmitted through a line 210 from the orifice meter
172, through a safety popoff valve 214, to a gas injection well
212, for disposal in shallow sand formations. The gas enters the
injection well 212 through the wellhead 216 thereof having a
high-low fail-safe valve 218 and a manually operated valve 220.
There is also a storm choke 222 beneath the marine bottom in the
injection well 212. If the back pressure in the shallow sand
formations being used for disposal should rise above a preset limit
of the popoff safety valve 214, the gas will be directed instead
through a line 134' to the surface where it will be flared. To heat
the cold fluids within the heat exchanger unit 206, warm water, at
150.degree. F. to 170.degree. F., is obtained from the TD 228 of a
water injection well 226 producing through a wellhead 227
comprising a manual valve 230 and an automatic setting valve 232,
and a rotary choke 234 having a pressure differential indicating
device 236 located thereacross. The warm water flows through the
heat exchanger unit 206, past a series of coils 205, in the line
204. From the heat exchanger unit 206, the then cooled water is
directed out through line 240 into the surrounding water near the
marine bottom. The rotary choke 234 is operated automatically in
response to a temperature signal obtained from the temperature
probe 238 previously described as located in the primary manifold
208 downstream of the heat exchanger unit 206. As the temperature
sensed by the temperature probe 238 decreases, the choke 234 is
opened further. If the temperature indicated reaches a specified
low level, the satellite station 10 is completely shut in.
FIG. 7 is a schematic diagram of another modification of the
Production System of FIG. 4, for a typical medium gas-oil ratio,
medium pressure well. A well is produced in the same manner as in
the previous two examples utilizing the same type of well and
wellhead equipment. In this modification the fluid, entering the
Production System portion through a branch conduit 76, is directed
through a one-way valve 241 into a heat exchanger conduit 242 which
traverses a heat exchanger unit 244. The produced fluid having been
produced from a TD of 10,000 feet makes its first pass through the
heat exchanger unit 244 at a temperature of 150.degree. F. to
170.degree. F. Upon exiting from the heat exchanger unit 244, a
pressure cut is taken through a variable choke 245. The now cold
fluids are passed back through the heat exchanger unit 244 by the
traversing heat exchanger conduit 245 to raise the temperature in
the expanded fluid to a prescribed minimum to prevent hydrate
formation and wax deposition. From the conduit 245 the fluid passes
into a collector manifold 246 containing a pressure sensor 238' and
temperature probe 209'. In collector manifold 246, the fluid from
the heat exchanger conduit is combined with the pressure cut fluid
from the other wells of the satellite stations through heat
exchanger lines 245'. The fluid from each well has previously been
directed through the heat exchanger unit 244, had a pressure cut
taken and then been passed back through the heat exchanger unit 244
through separate conduits. The combined fluid in the collector
manifold 246 is directed out through a conduit 247, making a final
pass across the heat exchanger unit 244 into another collector
manifold 248. From the manifold 248, the fluid is divided into
separate streams and directed into separators 72' through lines
249. The remainder of the fluid system is identical to that already
discussed with respect to FIG. 4. If the temperature indicated by
the temperature probe 209' decreases below a specified value, all
the wells of the satellite station 10 are shut in.
The schematic diagrams of FIGS. 4--7 illustrate examples of systems
to be used in specific cases. However, the features of the various
FIGS. can be combined in different arrangements to suit various
conditions. For instance, the electric-motor-drivepump 200 of FIG.
5 could be used with the modifications of FIGS. 6 and 7.
FIG. 8 illustrates a modified satellite station 10', similar to the
satellite station 10 of FIGS. 1 and 2, having the added advantage
of being able to be installed prior to completing any of the
production wells through the ring 51' of the base template 28'. In
this embodiment, instead of using cradling arms as illustrated in
FIG. 2, the satellite body is held in the satellite base 28' by a
central sleeve 250 depending from the lower end of the satellite
body 15' and automatic spring-loaded latches (not shown) over the
upper end of the well conductor pipe of the water well 52. The
latches can be disabled by a hydraulic pressure applied through the
conduit 252 extending between a manifold 254, forming a portion of
the framing of the base template 28', at the inner end, and a
quick-disconnect coupling section 256, at the outer end. The outer
end of the conduit is supported by a skeletal frame 258 to displace
the coupling section 256 outward of the well conductor pipes 34'.
The arrangement of the equipment within the satellite body 15' is
substantially the same as the arrangement within the satellite body
15 of the earlier discussed embodiment with the exception of the
orientation of the TFL tool 126 and the associated hydraulic
circuitry. In this instance, the connector units 54' are not
permanently attached to the satellite body 15' but instead are
stabbed-over tubing nipples 260 extending vertically out of the
upper end of the satellite body 15'. When a well is to be completed
through one of the upstanding well conductor pipes 34', a wellhead
14' is first mounted on the respective well conductor pipe 34'. A
connector unit 54' is later lowered from the surface to make the
connection between the well head 14' and the satellite body 15'.
The connector unit 54' consists of a curved tubing section 56' and
a vertical lubricator section 58'. The lower end of the lubricator
section 58' is stabbed over the tubing (not shown) extending
vertically out of the upper end of the wellhead 14', while the
outer vertical free ends of the curved tubing section 54' stabs
over the respective ones of the upstanding tubing nipples 260
extending out of the upper end of the satellite body 15'. In this
manner, with each connector section 54' being individually engaged
between the wellhead 14' and the respective upstanding tubing
nipples 260, greater tolerances can be allowed in installing the
satellite body 15'. Furthermore, an individual well can be produced
through the satellite station 10' while the remaining wells are
still being drilled and completed. The vertical orientation of the
tubing nipples 260 extending vertically into the satellite body 15'
presents no problem, each of the TFL storage chambers 146' is
reoriented into a vertical position so as to be coaxial with the
respective tubing nipples 260. The vertical position of the storage
chamber 146' permits the TFL tool 126' stored therewithin to move
easily into respective tubing nipples 260 so that it can be pumped,
under fluid pressure, through a full 180.degree. bend in the tubing
sections 56' of the connector unit 54'. Such a bend, of
180.degree., will not present any insurmountable problems requiring
only that the wells be spaced out far enough from the satellite
body 15' to obtain a 5-foot radius bend in the conduit. Stabover
connections, as discussed in this application, are more fully
described in the Manning application Ser. No. 663,799.
Although the present invention has been described in connection
with details of the specific embodiments thereof, it is to be
understood that such details are not intended to limit the scope of
the invention. The terms and expressions employed are used in a
descriptive and not a limiting sense and there is no intention of
excluding such equivalents in the invention described as fall
within the scope of the claims. Now having described the apparatus
and methods herein disclosed, reference should be had to the claims
which follow.
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