U.S. patent number 3,720,260 [Application Number 05/110,525] was granted by the patent office on 1973-03-13 for method and apparatus for controlling an offshore well.
Invention is credited to James Duck, James H. Lewis.
United States Patent |
3,720,260 |
Duck , et al. |
March 13, 1973 |
METHOD AND APPARATUS FOR CONTROLLING AN OFFSHORE WELL
Abstract
An improved system and method for bringing uncontrolled offshore
wells under control is disclosed and includes subsurface bifurcated
equipment for attachment to the pipe strings. The equipment
includes a supporting frame which isolates a section of pipe from
upper and lower sections. The isolated section of pipe and interior
pipes are successively sealed off, cut away and sealed off to
prevent any loss of fluid. Control fluids are injected into the
closed off pipe strings to bring the well under control.
Inventors: |
Duck; James (New Iberia,
LA), Lewis; James H. (New Iberia, LA) |
Family
ID: |
22333506 |
Appl.
No.: |
05/110,525 |
Filed: |
January 28, 1971 |
Current U.S.
Class: |
166/336; 30/97;
166/55; 166/360; 166/361; 166/364 |
Current CPC
Class: |
E21B
29/00 (20130101); E21B 33/063 (20130101); E21B
33/064 (20130101); E21B 29/08 (20130101) |
Current International
Class: |
E21B
33/06 (20060101); E21B 29/00 (20060101); E21B
29/08 (20060101); E21B 33/03 (20060101); E21B
33/064 (20060101); E21b 029/00 (); E21b
033/06 () |
Field of
Search: |
;166/55,55.6,.5,.6,315,93 ;30/94-97 ;251/1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Brown; David H.
Assistant Examiner: Favreau; Richard E.
Claims
What is claimed is:
1. A method for controlling pressure in a well string extending
from a surface strata to a point above a water level and which
includes at least one telescoping interior string of pipe
comprising the steps of
sampling the pressure in the annulus between the interior string of
pipe and the well string,
isolating a section of well string under water so that portions of
the well string above and below the isolated section are supported
relative to one another independently of the isolated section of
well string,
sealing off the isolated section of well string at spaced apart
locations to provide a sealed closed chamber about said section of
well string between said locations,
cutting away a portion of said sealed off isolated section of well
string within said chamber with a cutting means,
removing the cutting means from the well string, and
sealing off the cross-section of the cut-away portion of the
isolated section of well string within said chamber.
2. The method of claim 1 wherein said well string includes at least
two or more interior strings of pipe within the string of pipe, and
the first step is to sample the pressure in each string of
pipe.
3. The method of claim 2 wherein the steps of claim 1 are performed
for each string of pipe.
4. A method for controlling pressure in a well string having
multiple conduits and extending from a surface strata to a point
above a water level, comprising the steps of
attaching a support frame under water for supporting portions of a
well string above and below an isolated section relative to one
another and independent from said isolated section,
tapping the well string to determine which conduit is under
pressure,
stripping away any conduits not under pressure,
attaching a bifurcated sealing unit to a conduit under pressure to
seal against the outer wall of said conduit,
attaching a bifurcated cutting and sealing unit to said sealing
unit,
attaching a bifurcated sealing unit to said cutting and sealing
unit to seal against the outer wall of said conduit,
cutting away a peripheral section of said conduit with a cutting
means, and
removing the cutting means and sealing off said conduit.
5. The method of claim 4 and further including the steps of pumping
a control fluid into said conduit.
6. A method for controlling pressure in a well string extending
from a surface strata to a point above a water level comprising the
steps of
isolating a section of well string under water so that portions of
the well string above and below the isolated section are supported
relative to one another independently of the isolated section of
well string,
sealing off the isolated section of well string in an under water
air chamber,
sealing off the isolated section of well string at spaced apart
locations to provide a sealed closed chamber about said section of
well string between said locations,
cutting away a portion of said sealed off isolated section of well
string within said chamber with a cutting means,
removing the cutting means from the well string, and
sealing off the cross-section of the cut-away portion of the
isolated section of well string within said chamber.
7. Apparatus for obtaining control over an offshore well which
includes one or more coextensively extending conduits
comprising
means for coupling to a pipe conduit at spaced locations for
supporting portions of said conduit above and below an isolated
section relative to one another and independent from said isolated
section,
means for sealing a pipe conduit at spaced apart locations and
including means intermediate of said sealing means for cutting a
pipe conduit and means independent from said cutting means for
sealing off a cut pipe conduit, and
means for coupling to a pipe conduit and to a boat for transporting
equipment to and from said pipe conduit.
8. Apparatus for obtaining control over an offshore well which
includes one or more coextensive extending conduits comprising
means for coupling to a pipe conduit at spaced locations for
supporting portions of said conduit above and below an isolated
section relative to one another and independent from said isolated
section,
means for sealing a pipe conduit at spaced apart locations and
including slip means for gripping a conduit and preventing movement
relative to said pipe conduit, upper and lower segmented sealing
rings, pressure plate means disposed adjacent to said sealing rings
and hydraulic means for applying pressure to said rings,
means intermediate of said sealing rings for cutting a pipe
conduit, and
means independent from said cutting means for sealing off a cut
pipe conduit.
9. The apparatus of claim 8 and further including means forming a
pressure channel intermediate of said sealing rings, and means for
coupling said pressure channel to a pressure device for determining
the efficiency of the sealing rings.
10. The apparatus of claim 8 and further including mechanical means
for maintaining a force on said rings.
11. The apparatus of claim 10 wherein said mechanical means
includes a threaded jam member having a hydraulic passageway
therethrough.
12. Apparatus for obtaining control over an offshore well which
includes one or more coextensively extending conduits
comprising
means for coupling to a pipe conduit at spaced locations for
supporting portions of said conduit above and below an isolated
section relative to one another and independent from said isolated
section,
means for sealing a pipe conduit at spaced apart locations and
including slip means for gripping a conduit and for preventing
movement relative to said pipe conduit, means for normally
retaining said slip means in a retracted position, means for
actuating said slip means upon release of said retaining means,
means intermediate of said sealing means for cutting a pipe
conduit, and
means independent from said cutting means for sealing off a cut
pipe conduit.
13. Apparatus for obtaining control over an offshore well which
includes one or more coextensively extending conduits
comprising
means for coupling to a pipe conduit at spaced locations for
supporting portions of said conduit above and below an isolated
section relative to one another and independent from said isolated
section,
means for sealing a pipe conduit at spaced apart locations and
including means intermediate of said sealing means for cutting a
pipe conduit, said intermediate means including a segmented annular
ring member, means for rotating said ring member, cutting means
attached to said ring member and selectively movable between a
position in contact with a pipe conduit and a retracted position,
and
sealing means independent from said cutting means movable
transversely for sealing off a cut pipe conduit.
14. The apparatus of claim 13 and further including hydraulic means
for operating said cutting means.
15. The apparatus of claim 14 wherein said hydraulic means includes
at least one passageway extending through said ring member.
16. The apparatus of claim 14 wherein said hydraulic means includes
at least two passageways extending through said ring member.
17. The apparatus of claim 14 wherein said cutting means are
pivotally coupled to linkage means on said ring member and tiltable
relative to the surface of a pipe conduit.
18. The apparatus of claim 17 and further including means for
selectively operating said hydraulic means.
19. The apparatus of claim 17 wherein said hydraulic means includes
a first piston and cylinder coupled to said linkage means, a power
cylinder, and selectively operable valve means coupling said
cylinders to one another.
20. The apparatus of claim 19 and further including means for
selectively operating said valve means for moving said cutter means
into and out of engagement with a pipe conduit.
21. Apparatus for obtaining control over an offshore well which
includes one or more coextensively extending conduits
comprising
means for coupling to a pipe conduit at spaced locations for
supporting portions of said conduit above and below an isolated
section relative to one another and independent from said isolated
section,
means for sealing a pipe conduit at spaced apart locations and
including means intermediate of said sealing means for cutting a
pipe conduit and means independent from said cutting means for
sealing off a cut pipe conduit, and
resilient wall means forming an air chamber about said coupling and
sealing means.
22. Apparatus for obtaining control over an offshore well which
includes one or more coextensively extending conduits
comprising
means for coupling to a pipe conduit at spaced locations for
supporting portions of said conduit above and below an isolated
section relative to one another and independent from said isolated
section,
means for sealing a pipe conduit at spaced apart locations and
including means intermediate of said sealing means, said
intermediate means including a transverse bore for receiving a
cutter,
means for cutting a pipe conduit disposed in said bore and movable
for transversely severing said pipe strings, and
sealing means sized for reception in said bore for sealing off a
cut pipe conduit.
23. The apparatus of claim 22 and further including gate means for
sealing off said bore intermediate of said pipe strings and cutter
means.
24. The apparatus of claim 22 wherein said sealing means includes
selectively operable bypass means.
25. Apparatus for sealing off a pipe string comprising
sealing means engageable with the periphery of a pipe string,
means disposed in facing relationship to said sealing means for
engaging said sealing means substantially around its periphery,
said engaging means being segmented,
hydraulic means operative for forcing said engaging means against
said sealing means for sealing the periphery of a pipe string, said
hydraulic means including a piston and cylinder, and
mechanical means for additionally acting on said engaging means,
said mechanical means including a rod member engaging said piston
and having a hydraulic passageway therethrough.
26. The apparatus of claim 25 wherein said apparatus is in at least
two segments, and means for coupling said segments to one
another.
27. The apparatus of claim 26 wherein said apparatus includes upper
and lower sealing and hydraulic means and an intermediate testing
passage.
28. The apparatus of claim 27 and further including means on said
apparatus for locking said apparatus to a pipe string to prevent
longitudinal motion in at least one direction.
29. The apparatus of claim 28 wherein said locking means includes
oppositely arranged slip means.
30. The apparatus of claim 29 including means for normally
retaining said slip means in a retractable position and being
releasable to permit said slip means to engage a pipe string.
31. Apparatus for cutting a string of pipe including
a bifurcated housing member defining separate housing segments,
each of said segments including a ring segment mounted on the
housing for rotation about an axis means for driving said ring
segment,
cutter means on said segment including a linkage and actuative
means, and
means for coupling said housing segments to one another, said ring
segments having interconnections to form an annular ring member,
and
said cutter means having an operative surface pivotally coupled to
said linkage so that said surface is normal to said ring, said
linkage being operable to move said surface relative to said ring
member whereby said surface may be tilted relative to said member
and transversely movable sealing members disposed below said ring
member for sealing at a location above a string of pipe severed by
said cutter means.
32. The apparatus of claim 31 wherein said housing member has an
inlet port below said sealing members for injecting control
fluids.
33. The apparatus of claim 31 wherein said actuating means includes
a piston and cylinder coupled between said linkage and ring member
for actuating said cutter means.
34. The apparatus of claim 33 and further including passage means
extending through said ring member and coupled to said piston and
cylinder.
35. The apparatus of claim 33 wherein said actuating means further
includes tank means coupled to said piston and cylinder, and
selectively operable valve means for controlling the pressure in
said piston and cylinder.
36. The apparatus of claim 35, and further including passage means
extending through said ring member.
37. The apparatus of claim 35, and further including selectively
operable actuator means for operating said valve means.
38. The apparatus of claim 37, and further including means for
indicating the position of said ring member.
Description
BACKGROUND OF THE INVENTION
This invention relates to methods and apparatus for obtaining
control over an offshore well which is blowing out. More
particularly, the present invention is directed to systems for
operating under water to close off one or more pipe strings and for
permitting the application of a control fluid, such as mud or
cement, to kill an uncontrolled, pressurized well.
An uncontrolled offshore well involves an incredibly complex
surface operation to bring it under control and is usually
attendant with contamination of the water by the produced petroleum
products. This is because it is typically a situation wherein the
well is ignited or blazes with an intense fire which must be first
extinguished by fire fighters before remedial control operations
can be attempted to cap and control the well. Once the fire is
extinguished, there is the time interval between capping of the
well during which large amounts of oil and gas are produced to
contaminate the surrounding water areas. Alternative methods of
leaving the fire going and attempting to drill an offset well for
control purposes are time consuming, difficult to accomplish and
many times fail completely to obtain the objective. It is, of
course, in the interest of conservation of natural resources to
provide a way of controlling a well without permitting the
contaminating petroleum fluids to enter into the body of water
surrounding the well. Not only contamination is a problem, but time
is a factor as the cost of trying to control the well, the lost
time of production, the lost production and the great hazards
involved are monumental in scope and nature.
Accordingly, it is an object of the present invention to provide
new and improved systems for obtaining control over an uncontrolled
well without the attendant loss of petroleum fluids and for
obtaining control in a relatively short period of time and with
reduced hazards.
SUMMARY
The present invention involves a system using bifurcated apparatus
which is installed on pipe strings below a water level. A
supporting frame is attached to an outer pipe string and supports
the upper section of a pipe relative to a lower section of the pipe
while isolating a section of pipe free of weight or tension. On the
isolated section of pipe a base member is installed with a sealing
means to seal off the periphery of the pipe; a cutting and sealing
unit and an upper sealing unit are next installed. In one form of
the invention, the pipe section is cut completely in two and sealed
off, whereupon a control fluid can be applied to kill the well. In
another form of the invention, the pipe sections are individually
cut away, sealed off and killed in a sequential manner. In still
another form, the operations can be conducted in an air
chamber.
The apparatus of the invention includes bifurcated assemblies for
sealing and cutting off the pipes. In the sealing assemblies,
provision is made for controlling the fluid under pressure. In the
cutting and sealing unit, the cutter is operative to remove a
section or sections of pipe in front of a sealing unit and is
retractable to permit operation of the sealing unit.
These and other features of the invention will be apparent from the
detailed description hereinafter provided, wherein reference is
made to the accompanying drawings.
DRAWINGS
In the drawings:
FIG. 1 is a pictorial representation of an offshore well and
illustrates broadly components of the present invention;
FIG. 2 is a view of the isolated section of pipe and apparatus for
cutting and sealing off the outer pipe with respect to a first
inner pipe;
FIG. 3 is a view of the isolated section of pipe and apparatus for
cutting and sealing off the first inner pipe with respect to a
second inner pipe;
FIG. 4 is a view of the isolated section of pipe and apparatus for
cutting and sealing off the second inner pipe with respect to a
third inner pipe;
FIG. 5 is a view similar to FIG. 4 and further illustrating a flow
control unit;
FIG. 6 is a view in cross-section taken along line 6--6 of FIG.
2;
FIG. 7 is a view of the work support frame attached to a pipe
string;
FIG. 8 is a view in cross-section taken along line 8--8 of FIG.
7;
FIG. 9 is a view in cross-section taken along line 9--9 of FIG.
8;
FIG. 10 is a view in cross-section taken along line 10--10 of FIG.
7;
FIG. 11 is a view in cross-section taken along line 11--11 of FIG.
2;
FIG. 12 is a view in cross-section taken along line 12--12 of FIG.
11;
FIG. 13 is a view in cross-section taken along line 13--13 of FIG.
14;
FIG. 14 is a view in cross-section taken along line 14--14 of FIG.
13;
FIG. 15 is a view in cross-section taken along line 15--15 of FIG.
14;
FIGS. 16 and 17 are perspective views illustrating the operation of
the cutting means;
FIG. 18 is a schematic illustration of a hydraulic system
illustrated in FIG. 13;
FIG. 19 is a schematic illustration of a selectively operable
mechanism for actuating the hydraulic mechanism of FIG. 18;
FIG. 20 is a schematic illustration of an alternative form of
hydraulic mechanism;
FIG. 21 is a view in cross-section illustrating a sealing
means;
FIG. 22 is a schematic illustration of still another alternate form
of hydraulic mechanism;
FIG. 23 is a view in cross-section taken along line 12--12 of FIG.
11 and enlarged in cross-section;
FIG. 24 is a schematic illustration of an air chamber means;
FIG. 25 is a view in cross-section of an alternative cutting and
sealing system;
FIG. 26 is a view in cross-section taken along line 26--26 of FIG.
25;
FIG. 27 is a view in cross-section taken along line 27--27 of FIG.
25;
FIG. 28 is a perspective view of a sealing ram for the unit shown
in FIG. 25;
FIG. 29 is a view in cross-section of an alternative construction
for a sealing ram; and
FIG. 30 is a schematic illustration of an alternative form of the
hydraulic system.
In a typical offshore well operation for which the present systems
are designed, an offshore platform 30, as shown in FIG. 1, is
supported by struts 31 on the subsurface 32 below the water level
33. One or more telescoped pipe strings 34-36 extend from the
surface of the platform 30 through the water, then through the
underlying substrata to earth formations below the body of the
water. As is typical in this sort of operation, a so-called
"surface casing" 34 extends from a platform into the earth
formations for an interval of length and is commonly used to
prevent the hole from caving in. Successively smaller diameter
pipes 35 and 36 are telescoped through the surface casing and
extend to successively increased depths into the earth formation
and are commonly cemented into place. Thus a typical well string
from an offshore well platform can include a number of
telescopically arranged pipe strings, each extending to a deeper
depth within the formation, and one or more of the interior pipe
strings traverse an earth formation through which petroleum
products are produced.
With a given offshore production system as described above, if a
blowout occurs where the petroleum products are produced in an
uncontrolled fashion through the pipes to the surface platform, it
is almost inevitable that ignition of the products will occur and a
fire will be produced which is continuously fed by the pressurized
products produced from the formations. The system of the present
invention contemplates an underwater operation which can be
performed in, say, the upper thirty feet of water where a
subsurface swimmer can operate for prolonged periods of time
without incurring the usual diving hazards. The system broadly
contemplates the location of a work boat 37 to the windward side of
the platform 30, and, through the use of flotation equipment, a
swimmer attaches a towing guide ring 38 to the outer pipe string
34. The boat 37 is suitably anchored in place to maintain a given
position. Cables are attached between the boat 37 and the towing
ring 38 to transport equipment to and from the pipe string 34. A
subsurface frame 39, which is bifurcated, is first towed into place
under water and is attached at spaced locations 40, 41 along the
outer pipe to provide a rigid support between the upper part 42 of
the pipe and a lower part 43 of the pipe 34, so that the pipe
section 44 intermediate of the upper and lower support locations
40, 41 can be completely removed with the support frame 39
providing a means for maintaining the upper part 42 of the pipe and
any assemblages which may be attached thereto from moving downward.
From the boat, air, hydraulic and electrical lines for the units
are cabled to the frame 39 for operation of the various units.
After the working support frame 39 is attached to the pipe 34, a
hot tap machine 45 is towed into place and fixed near the upper end
of the pipe section below the upper support location 40, as shown
in FIG. 2. The hot tap machine 45, which is conventional, is
strapped to the pipe 34; a tap 46 is drilled through the first pipe
wall; and the pressure within the pipe is sampled by a gauge 47. If
there is no pressure, it may be reasonably assumed that the annular
area 48 between the outer pipe and the first inner pipe 35 is not
the cause of the blowout, and the tapping machine is operated to
pierce the second pipe wall. This tapping operation is continued
until the annulus between pipes, where the pressure or the fluids
produced in the well are coming from, is discovered.
In the most complex situation which can be encountered, there can
be pressure in each of the annuluses 48 and 49 of the pipes as well
as the central conduit 50.
Assuming an extreme case, in the practice of the systems of the
present invention the outer pipe 34 is sealed off around its outer
periphery at a location just above the lower support location 41
with a base member unit 51 (FIG. 2). Unit 51 is bifurcated so that
it can be bolted in place to the outer pipe 34. The lower base
member unit 51 is also a sealing device, and, after the base member
unit 51 has been tested to ensure that a seal is maintained between
it and the outer surface of the pipe 34, a bifurcated cutting and
shutoff unit 52 is towed into place and sealingly attached to the
base member unit 51 in position for operation. At the upper end of
the cutting and shutoff assembly 52, a blowout preventer unit 53 is
sealingly attached so that the assembly includes an upper blowout
preventer unit 53, an intermediate shutoff and cutting unit 52, and
the lower base unit 51. With the pipe thus sealed at spaced
locations by the sealed assembly, the cutting and shutoff unit 52
is actuated so that a cutter 55 cuts away a section 56 of the outer
pipe (shown in dashed line), and, following the cutting operation,
sealing means 57 in the shutoff and cutting unit are actuated to
seal off the annulus between the outer pipe and the next inner
pipe. For convenience of illustration, cutter 55 and sealing means
57 are shown in the plane of the drawing of FIG. 2 and are only
schematically illustrated. The actual construction will hereinafter
be more fully explained.
At this point, if so desired, control mud or liquid such as cement
may be pumped into this annulus via a port 57A to control the
pressure in the annulus 48 between the pipes 34 and 35.
To control the pressure within the next inner annulus 49 (as shown
in FIG. 2), the upper blowout preventer 53 is removed, and the
outer pipe section 44 between the support locations of the working
frame is removed. The pipe section 44 is removed by conventional
cutting. Another cutting and shutoff unit 59 is then sealingly
attached to unit 52, and unit 59, in turn, is sealingly capped at
its upper end with a blowout preventer unit 60 so that there is
effectively a seal between the upper blowout preventer 60 on the
first inner pipe 35 and the sealing means 57 of the first cutting
and shutoff unit 52 on the outer pipe 34. The operation is then
repeated where an annular section 61 of the pipe 35 is cut out, and
the shutoff unit 59 is operated to seal off the second inner
annulus 49. Following this, control mud or other liquids may be
pumped into the second annulus via a port 61. The section of the
first inner pipe may be cut away then between the support locations
of the working frame, and still another cutting and shutoff unit
can be used on the next annulus between the pipes. This operation
is repeated until the final interior pipe 36 is cut away, as shown
in FIG. 4, and the cross-section of the pipe is closed, which
completely caps off the well. The control fluids which may be
injected, of course, into the various annuluses, as desired, have
controlled the well. Once the well has been controlled, the
apparatus can be removed and conventional remedial operations
performed on the well. During this entire operation, it will be
appreciated that the fire is permitted to continue so that there is
no pollution of the water and that, as the shutoffs of each
pressured annulus of pipe are obtained, there is no escape of
contaminating fluids to the water. In addition, the operation is
relatively quick, and at all times the well is under control.
Referring again to FIGS. 1, 2 and 6, the bifurcated towing ring 38
is first attached by a swimmer near the upper end of the pipe just
below the water level, and tow cables 63, 64 are coupled between
winches 65 on the boat 37 and the towing ring so that equipment may
be floated into place. The ends of the towing cables 63,64 are
respectively attached to separate winches on the boat so that
positive to-and-fro movement of equipment can be accomplished. The
equipment is transported by use of a float 66 and a cable connector
(not shown) for the cable and transporting the equipment under
water to the well string.
After the towing ring 38 is installed, the supporting work frame 39
in bifurcated sections is towed into place and attached to the pipe
so that it provides upper and lower supporting members 67, 68
respectively attached to the pipe 34. The upper supporting member
67 has gripping means which hold the upper section of the pipe from
moving downward, and the lower ring of the supporting work frame 39
has gripping means which prevent the work frame from moving
downward relative to the pipe 34. Thus, a section 44 of pipe 34 is
isolated between the upper and lower support rings 67, 68 and is
effectively isolated from the pipe string 34 so that it can be
removed. After the working station 39 is installed, the hot tap
apparatus 45 is floated into position. A diver attaches the hot tap
device to the upper end of the pipe by strapping it to the outer
section of the pipe, and the tap is operated to drill through the
successive pipe walls -- the pressure being sampled as the tap
progresses. The purpose of this test is, of course, to determine in
which annulus the pressure exists.
A base sealing unit 51 which is bifurcated is next floated into
position and attached to the outer pipe near the lower ring 68. The
base unit 51 includes a sealing member 69 for sealing the annulus
of the pipe and slip members 70 which firmly fix the base member to
the pipe so that it cannot move. After the base unit 51 is located
in position, the bifurcated cutting and sealing unit 52 is floated
into place and attached to the lower base unit 51 and to the pipe
34, and the bifurcated upper sealing unit 53 is attached to the
cutting and sealing unit 52. In the example shown, it is assumed
there is pressure between the annulus of the outer and first inner
section of pipe, so that the units 51 and 53 positioned on the
outside of the pipe 34 provide upper and lower seals on the pipe.
The cutting unit 52 is operated to cut away an annular section 56
of the pipe 34 and, after the annular section of pipe is cut away,
the sealing member 57 is actuated to seal off the outer section of
the first inner pipe 35, which effectively seals the annulus 48
from a point below the sealing unit 57 and the seal 51 on outer
pipe 34. By means of a port 57A below the sealing unit 52, control
fluids such as mud or cement may be pumped in the annulus to kill
the pressure in this section of the well. The upper bifurcated
sealing unit 53 is then removed since the cutoff sealing devices 57
provides a seal, and the outer section of the casing 34 is cut away
by means of an underwater torch or the like and removed. If
desired, the first inner pipe can be tied to the outer pipe by
welding or an attaching device (not shown).
Next, another bifurcated cutting and sealing unit 59 is attached to
the first cutting and sealing unit 52, and an upper sealing unit 60
is attached to it. The next section of pipe 35 is cut away, and the
sealing unit 59 is operated to close off the annulus between the
pipe 35 and the pipe 36. If there is pressure in the annulus,
control fluid such as mud or cement can be injected through port 61
in the unit to kill the well.
To control the last section of pipe, the upper sealing unit 60 is
removed, and a cutting and sealing unit 62 is substituted after the
intermediate section of pipe 35 has been cut away. A sealing unit
69 can be installed, and the inner pipe 36 is cut as described
before. The sealing unit 62 operates to close off the
cross-sectional area 50 of pipe 36. The well may be killed through
injection of a control fluid through the port 70 in the sealing
unit 62. Alternatively, the sealing unit 69 can be removed and an
exterior port device 71 can be attached to the upper end and
operated to kill the well by injecting fluids after the sealing
unit 62 is opened. When this final operation is conducted, it will
therefore be appreciated that each section of the pipe is
controlled and that there is no possibility of contamination of the
water by the petroleum products since they are controlled in
place.
Referring now to FIG. 6, the tow ring 38 is shown which is
comprised of bifurcated half-sections 74, 75 which can be bolted
together about the periphery of the pipe 34. Around the outside
perimeter of the tow ring 38 are a number of eyelets 76 and sheaves
77 attached by swivels 78 or the like to receive the tow line from
the boat. The tow cables 63, 64 can be inserted, for example, by a
swimmer taking a nylon rope from the boat and passing it through
the sheaves and returning it to the boat where a cable can be
attached to one end of the rope and drawn through the sheave and
attached to a winch. It is preferable that a winch be attached to
each end of the cable through a suitable cathead or the like,
whereby the cable can be positively pulled in either direction for
moving equipment to and from the well site.
The work platform as shown in FIGS. 7 and 8 includes upper and
lower ring members 67, 68 which are bifurcated and provided with
bolt means 79 for attaching the two halves of a ring to one
another. Each half ring has two or more supporting frames 80, 81
disposed at 90.degree. relative to one another to form a
symmetrical, somewhat diamond-shaped form with diagonal arms,
intermediate parallel support members and lower diagonal arms and a
lower working platform 82. It will be obvious that the arm members
are required to support the weight of the pipe above the upper ring
67 as well as any other equipment on the pipe and, therefore,
should be sufficient and adequate to support the load. In this
regard, suitable additional bracing and support members may be
employed to provide adequate bracing. It is the function of the
supporting frame member 39 to support the section of the pipe 34
above the upper support ring 67 and to transmit this load through
the supporting frame members to the lower support ring member 68
which is, in turn, attached to the lower section of pipe 34. The
attachment of the upper and lower support rings is not only by
means of the clamping connection of the bifurcated ring members but
also by virtue of slips 83 which are disposed around the periphery
of the support rings. As shown in FIG. 9, the slips 83 in the lower
support ring 68 are mounted in inclined recesses 84 in the inner
wall of the ring, and the sliding surfaces can be dovetailed to one
another if so desired. The slips 83 are respectively engaged by
springs 85 within the ring 68, so that the springs tend to urge the
slips 83 along the inclined plane to move them inwardly into
engagement with the wall of the pipe 34. The slips 83 are
ordinarily prevented from actuation by means of screw members 86 or
the like which are threadedly received in openings 87 in the slips
and pass through the housing sections so that the slips, in a
retracted position, compress the springs and would normally be out
of engagement with the wall of the pipe. After the apparatus has
been positioned on the pipe, the screw members 86 are released so
that the springs can urge the slips into engagement with the wall
of the pipe. As shown in FIG. 10, the slip arrangement within the
upper supporting ring is the same as the slip arrangement in the
lower supporting ring, except that it is reversed so that the
weight of the pipe acting through the slip is transmitted to the
supporting ring. That is, slips 83a are urged downwardly by
springs, and bolts 86a are used to retain the slips in a retracted
position. If desired, oppositely opposing slips can be used in each
of the supporting rings.
Referring now to FIGS. 11 and 12, the lower base and sealing unit
51 is illustrated in cross-section. The lower base and sealing unit
51 is comprised of two semi-circular sections 89, 90 which can be
bolted together around the periphery of the pipe 34. Vertical holes
88 pass through the assembly for bolting the base assembly to
adjacent sealing and cutting units or the like.
Looking at FIG. 12, which is a vertical cross-section, the interior
wall 91 of the sealing assembly 51 has upper and lower annular
shaped recesses 92, 93 as well as an intermediate annular recess
94. In the lower section of the interior are slips 95, 96 which are
arranged on inclined surfaces and may be dovetail-connected to the
inclined surfaces for attachment. The slips use screws 97 for
maintaining the slips in a normally retracted position and spring
members 98 behind the slips for urging the slips into gripping
engagement with the casing. As illustrated, the slips are arranged
in opposite directions so that the housing will support weight in a
downward direction, for reasons which will hereinafter become more
apparent. Within the upper and lower annular recesses 92, 93 are
semi-circular lead sealing members 94a, 94b, and behind each of the
sealing members 94a, 94b are arcuately shaped plates 96. As shown
in FIG. 11, the semi-circular sealing members 94a, 94b may be
displaced slightly upon location on the pipe so as to avoid a
direct opening to the split between the ring members. The arcuately
shaped backup members 96 are disposed around the circumference of
the lead members 94a, 94b so as to form a more or less continuous
backup ring. To each of the arcuate members 96 is attached a piston
99 which is slidably and sealingly received in a cylinder 100. Each
cylinder 100 is, in turn, connected via a hollow bolt 101 to a
source of hydraulic pressure, not shown. The hollow bolt 101, as
shown in FIG. 23, has a threaded member 102 with a passageway 103
therethrough, and within the chamber, side ports 104 are provided
for admitting hydraulic pressure into the cylinder. Through an
exterior coupling to the hollow bolt, hydraulic pressure can be
applied to the cylinder 100, and the piston 99 applies pressure
through the arcuate members 96 to the lead ring segments 94a and
94b to urge them into sealing engagement with the pipe. At the same
time, the bolt member 101 can be actuated through its threaded
arrangement in the housing by means of the lug attachment 105 to
mechanically engage the rearward end of a piston and maintain the
piston with a mechanical force on the lead ring independent of
hydraulic force. Thus a mechanical backup is provided for the
sealing member. Between the sealing members, seals (not shown) are
provided between the sections 89 and 90. To test the tightness of
the seal, the sections 89, 90 have a recess 90a intermediate of
seals 94a, 94b. The recess 90a is coupled to a pressure gauge 90b
and a valve 90c. Pressure can be applied to the recess 90a to
determine if the seals are tight.
Referring now to FIGS. 13 and 14, a cross-section is illustrated of
the cutting and sealing unit 52 which is affixed to the top of the
base unit 51. The cutting and sealing unit 52 has a large hollow
casing or housing 106 in which a pair of rams 107, 108 (FIG. 13)
are diametrically opposed to one another and are mounted on
parallel guideways 109 (FIG. 14) to be reciprocated backward and
forward by means of a hydraulic cylinder arrangement 110. The rams
107, 108 include forward surfaces 111, 112 which engage one another
as well as semi-circular recesses 113, 114 which are sized to the
outer diameter of the interior casing. Suitable sealing members
(not shown) are disposed along the engaging surfaces and elsewhere
to provide a fluid-tight sealing arrangement when the rams are
closed on the pipe (FIG. 15) so that fluid flow in a vertical
direction past the rams is prevented. In the rearward part of each
ram, offset shoulders 116 can be provided together with sealing
means to seal against surfaces at the rearward location in the
housing. Thus, it will be appreciated that if the outer casing 34
is removed, the rams 107, 108 can be closed and sealed with respect
to the inner pipe 35 (FIG. 15), and fluid flow in a vertical
direction past the rams is prevented. As illustrated, the housing
106 is bifurcated and arranged for coupling about the pipes, and
suitable sealing members are provided to seal these halves with
respect to one another. The housing 106, when completed, has an
annular shaped ring groove 120 (to be explained in detail later)
which carries a split gear ring 121. The gear ring is assembled and
has outer gear teeth which engage oppositely disposed spur gears
123 which are coupled to hydraulic motors 124. The hydraulic motors
124, when actuated, serve to rotate the gear ring 121. Mounted on
and above the gear ring is a linkage mechanism 122 which is pivoted
to the gear ring 121 at pin 122a, and a link arm 122b has one end
connected to a hydraulic cylinder 125 and an opposite end connected
to a cutter 126. As illustrated, the cutter 126 is pivotally
connected at 127 to the linkage arm 122b and extends vertically
over a greater distance than the width of the rams. The hydraulic
piston 125, when actuated, urges the cutter 126 into engagement
with the circumference of the pipe 34 and, by virtue of tungsten
carbide tip surfaces, the pipe is cut away across the width of the
cutter.
Referring to FIG. 16, a cutter blade is illustrated in contact with
a casing pipe 34 and in FIG. 17 in a position where the pipe 34 has
been cut away. The cutter blade has a generally curved forward
surface 130 and a rearward, downwardly extending surface 131 which
is parallel to the front surface 132 of an extension on arm 122b so
that the arm ordinarily biases the blade 126 into contact with the
casing 34. When the blade is positioned in front of the ram, as
shown in FIGS. 16 and 17, a rearward motion of the linkage arm 122b
will cause the lower portion of the blade to engage the ram, and it
will tilt upwardly as the arm moves away from the pipe, so that the
blade may be removed from the location between the ram surfaces,
thereby permitting the ram to be closed.
A small projection member 135 is mounted on the gear 121 so that
the rotative position of the ring within the housing can be
indicated. Thus, each time the ring 121 is rotated, each of the
limit switches 136, 137 will be actuated. The location of the
projection member 135 relative to the ring 121 is such that when
the blades 126 are in line with the rams, the projection 135 will
be intermediate of the two switches 136, 137. At this location, a
second cylinder 140 with an access opening 141 will be disposed
adjacent to an access port 142 in the housing.
The sealing means or blowout preventer 53 includes a bifurcated
housing member 144 which has sections carrying sealing rams 145,
146 in suitable guides, and, when assembled, the rams 145, 146 are
oppositely disposed relative to one another. Hydraulic means 147,
148 are provided for moving the rams in a conventional manner. In
the position illustrated in FIG. 14, the rams 145, 146 seal against
the pipe 34 and also provide a seal against travel of fluid in a
vertical direction through the ram.
Turning now to the hydraulic system for operating the cutters, it
is the purpose of the system to actuate and retract the cutter. A
first system is illustrated in FIGS. 18 and 19 where in a pressure
tank 140 is coupled via a normally closed solenoid valve 150 to a
hydraulic cylinder 125 containing a piston 151 coupled by a piston
rod 152 to the linkage arm 124. A spring 153 in the cylinder 125
normally urges the piston toward a retracted position. A return
conduit 154 couples the cylinder 125 to the tank 140, and it has a
normally closed solenoid valve 155. To operate the system the tank
140 is charged with air under pressure via inlet 141 which includes
a one-way check valve normally preventing escape of pressure. When
it is desired to apply pressure to the linkage, the valve 150 is
opened by closing switch 156 which closes an electrical circuit,
and valve 150 is opened and latched in this position. The
spring-biased side of cylinder 125 is at atmospheric or a relative
low pressure so that the piston 151 is acted upon to apply pressure
to the linkage 124 and, hence, the cutter blade. Stops 157, 158 on
the piston rod 152 and housing limit the inward travel of the blade
so that only one pipe is cut. To reverse the force on the linkage,
a solenoid valve 155 is opened by closing switch 159 which closes
an electrical circuit, and the valve 155 is latched in an open
position. The opening of valve 155 equalizes the pressure across
the piston 151, and spring 153 retracts the linkage. Of course, a
high pressure external to cylinder 125 greater than the internal
pressure can also serve to retract the linkage.
Switches 156 and 159 are selectively operable. As shown in FIG. 13,
switches 156 and 159 are mounted on the ring 121, and an actuating
mechanism 160 is such that when actuator 135 is disposed
intermediate of switches 136 and 137, switches 156 and 159 are on
opposite sides of the actuating mechanism 160 and blade 126 is in
front of a ram. The actuating mechanism 160, as shown in FIG. 19,
is comprised of a threaded member 161 with fixed guide members 162,
163 in guide tracks 164, 165 so that the screw member 161 cannot
rotate. A gear 166 is mounted between the guide frame and has a
threaded opening received on the threaded member 161. A motor 168
drives a gear 167 which, in turn, rotates the gear 166 causing the
threaded member to move either forward or backward, depending upon
the rotation of motor 168. Hence, when the switches 156 or 159 are
located to either side of the actuating mechanism 160, it is
actuated to position the threaded member 161 in position to actuate
a switch 156 or 159. The switch 156 or 159 is selectively actuated
by turning the gear an appropriate angular amount. After actuation
of a switch, the threaded member 161 is retracted and the gear 121
can be rotated. Thus, each switch 156 or 159 can be selectively
actuated.
Referring now to FIG. 20, another embodiment of the hydraulic
system is illustrated. Tank 140 and cylinder 125 are as described
heretofore. To bleed off the pressure from the piston for return of
the piston rod, the high pressure side of the cylinder 125 is
coupled via a conduit 170 to a closed chamber 171 in each segment
of gear 121. Chamber 171 has a lower opening 172 which is lined
with a rubber insert 173 attached to a teflon member 174 (FIG. 21).
Member 174 is aligned relative to an upstanding flange 175 on the
housing to provide a sealing surface. As shown in FIG. 21, gear 121
has a downwardly extending flange 176 intermediate of upwardly
extending flanges 175, 177 on the housing. U-shaped sealing members
178, 179 constructed of teflon are disposed between adjacent
flanges to provide a pressure seal in both directions. It will be
appreciated that since gear 121 is in two pieces, the sealing
members are separate parts and closed at each end. The housing has
an access passage 180 coupled to a conduit 181 which includes a
selectively operable valve 182. Valve 182 may be located exterior
to the housing where conduit 182 can be opened to relieve pressure
on the cylinder 125. Alternatively, supplemental pressure can be
applied via the conduit 181 to the cylinder. Also, as illustrated,
gear 121 is contained in the housing by roller bearings which
provide a thrust support and permit ease of rotation.
Referring now to FIG. 22, a different embodiment is illustrated
wherein the opposing ends of cylinder 125 are coupled via conduits
183, 184 to separate chambers 185, 186 which are, in turn, coupled
to conduits 187, 188 via ports 189, 190. Conduits 187, 188 are
extended to exterior control systems whereby the pressure in the
cylinder 125 can be selectively controlled to apply pressure to the
cutting blade as well as retract it.
Referring to FIG. 30, still another variation for controlling the
hydraulic system 125 where one or more flexible conduits 125a are
passed through the housing is shown. In this arrangement, the gear
is oscillated between angular positions rather than rotated so that
a direct connection can be made to the hydraulic cylinder 125.
Turning now to FIG. 24, a system is illustrated wherein the working
frame 39 and working area is enclosed by a fabricated housing 192
of resilient material such as reinforced rubber. The housing is
provided with upper and lower conduits 193, 194, with internal and
external control valves and an upper valve controlled inlet conduit
195 through which air pressure can be supplied. The housing 192 is
attached to the pipe 34 by upper and lower strap means 196, 197 and
has a vertical split 198 which is clamped shut after installation
by means of suitable clamping means which are schematically
illustrated. A manhole opening and cover 199 are provided in the
lower end of the housing for access. By virtue of the housing,
water can be removed from the working area by air pressure, and the
various units employed can be welded in place.
Another form of the present invention is illustrated in FIGS.
25-29. In this embodiment, the working equipment includes a
bifurcated lower base member 200 which has opposing slips 201 and
may include means providing an annular seal as described
heretofore. Attached to the base member 200 is a blowout preventer
device 202 which has rams 203, 204 which are selectively operated
in a conventional manner by hydraulic means to seal off the casing
34 and prevent fluid flow in a vertical direction. Attached to the
preventer 202 is a cutting and sealing unit 205. Above the cutting
and sealing unit 205 is another blowout preventer 206 with sealing
rams 207 and 208 to sealingly engage the casing and prevent fluid
flow in a vertical direction. Attached to the preventer 206 is an
upper base member 209 which includes oppositely disposed slips 210
and which can include additional sealing means. The units as
described are bifurcated along the center line and a plane
perpendicular to the plane of the drawing. As will be apparent from
the organization, the pipe 34 is sealed above and below the cutting
and sealing unit 205.
The unit 205 includes a central bore 212 which has a diameter
greater than the diameter of the pipe 34. The bore 212 terminates
to one side of unit 205 in a tapered wall seating recess 213. The
bore 212 is continued in a housing port 215 and terminates at a
wall 216 which forms part of a hydraulic system 217. The hydraulic
system includes a piston 218 which on one side is coupled by a
piston rod 219 to a mill cutter 222 disposed in the bore 212. The
other side of the piston 218 is coupled by a piston rod to a
square-shaped driving shaft 221. The shaft 221 is slidingly
received in a socket in a gear 223 which is suitably supported to
prevent sidewise motion yet permit rotation. The gear 223, in turn,
is driven by a gear 224 coupled to a drive shaft of motor 225. When
the motor 225 is operated, the shaft 221 and hence the mill cutter
222 are rotated. The piston 218 is actuated by hydraulic pressure
to move the mill cutter 222 into cutting engagement with the pipe.
Thus, it will be readily appreciated that cutter 222 can be driven
to cut through all pipes traversing the bore 212 and thereafter
retracted to the position illustrated.
After the above operation the pipe 34 is severed or cut in two. To
seal off the cross-section of the pipes, the housing 205 has a
transversely located shut-off ram 227 which is selectively operated
by a hydraulic system 229. From the open position shown, the ram
227 is movable downwardly into a tapered recess 228 to seal off the
bore 212, thereby isolating the cutting mill from the pressure in
the pipe conduits.
When the cutting mill 222 is isolated from the pipe strings, the
housing 215 is removed and a ram housing 230 attached to flange
231. The ram housing 230 includes a hydraulic system 232 and a ram
233 attached to a piston rod 234. After attachment to flange 231,
transverse gate 227 is opened and ram 233 passed through bore 212.
The ram 233 has a forward tapered nose section 235 which seats in
the housing recess 213 as shown in FIG. 26. The shape of ram 233
includes a rearward cylindrical portion 237 provided with an
annular seal 238, a central portion having parallel flat surfaces
239 and side cylindrically shaped surfaces 240, and the tapered
nose piece 235. Lengthwise extending seals 242 are provided along
the sides 240. When the ram 233 is in position, it seals with
respect to the body of housing 205 to close off the fluid flow and
therefore control the well. Port 244 can be used to inject a
control liquid.
To facilitate the closing of ram 233, it may be provided with a
bypass. As shown in FIG. 29, a cylindrical passageway 250 extends
between surfaces 239 and has an upper restricted opening 251 and an
inner tapered seat 252. In the lower surface 239 are access slots
254 communicating with the spaces between the flutes 255 in the
bore 250. A sealing ball 256 is located in an angularly disposed
passage 258 and compresses spring 257 while being held in place by
a pin 260. The pin 260 is located in a longitudinally extending
passage in the ram 233 and abuts an actuating rod 262, which has
one end extending beyond the end of the ram 233. A shearable
connection 263 normally holds rod 262 in a fixed position until the
end of the rod 262 engages the housing, thereby slipping pin 260
from the bore and permitting the ball 256 to be released and seated
in the seat 252 to shut off fluid flow. With this type of valve,
fluids can be pumped through the valve into the well but will not
return because of the valve action of the ball.
From the foregoing description, it will be apparent that the
concept of the present invention involves a subsurface or
underwater operation for control of a well. Fundamentally, it
involves bifurcated units which can be attached to a pipe under
water and provide a sealed control apparatus which permits cutting
and sealing of well conduits while under pressure without loss of
fluids. The schematic illustrations depict the technique of
strapping and sealing units to the pipes under water. It is
contemplated that the operations can be monitored by the use of
underwater cameras both inside and outside of the equipment. The
various control lines for air, hydraulic and electrical power are
supplied from the boat in a conventional manner.
In the operation of the present system, as described heretofore,
the boat 37 is located in position. The towing guide ring 38 is
attached under water to the pipe conduit 34 and the tow cables 63,
64 attached. The various pieces of equipment are then towed into
the working location by use of the cables 63, 64 and flotation
equipment such as a buoy 66.
The working frame 39 is attached to the pipe 34 to provide the
rigid support for the pipe and the isolation of a pipe interval on
which operations can be conducted. Frame 39 when made in bifurcated
sections is quickly and easily installed although, if desired, a
supporting frame can be constructed in place by conventional
underwater construction techniques.
The next step is to determine the location of the pressure in the
pipe conduits so that the situation can be evaluated.
Alternatively, if testing is not performed, the pipe sections can
be sequentially isolated. The presence of pressure is determined by
use of a conventional hot tap machine which can selectively sample
each pipe under pressure control and determine the presence or
absence of pressure. Use of the control cutting and sealing units
is not necessary for outer sections of pipe which are not under
pressure. In this case, such unpressurized pipe conduits can be
safely stripped away first.
To control the pressurized conduit, a cutting and sealing unit is
positioned on the pipe and sealing means provided above and below
the unit. This assembly is a sealed chamber about the pipe so that
the pressurized pipe can be cut and then sealed off. After sealing
off the pressurized conduit, well control fluid is pumped to the
pressurized pipe to control the well.
As illustrated in FIGS. 13-15, the bifurcated cutting and sealing
unit 52 includes mirror sections which join to form an assembly
which along one axis includes sealing rams. A rotatable cutter
assembly is provided which has an actuator 135 on a gear 121 to
indicate position. The gear 121 is driven by a hydraulic motor 124
which can be reversed, and actuator 135 cooperates with switches
136, 137 on the housing to indicate position. When the actuator 135
is intermediate of switches 136, 137, the cutters 126 are disposed
in front of the rams and an inlet port 141 in a tank 140 is
positioned opposite to an access port 142 in the housing. Thus,
tank 140 can be charged with air under pressure through the access
port 142 by attaching an air hose to port 141. Another actuator 160
is operated, and switch 156 can be actuated by a partial rotation
of gear 121. Switch 156 actuates a valve 150 so that pressure is
applied to the cutter 126 via a linkage 122. Actuator 160 is
retracted and gear 121 rotated so that cutter 126 wears away a
section of the pipe. As illustrated, cutter 126 cuts a section of
pipe greater in width than the width of the rams. A stop 157 on the
piston rod engages a stop 158 on the gear housing 121 to limit the
inward travel of the cutter 126. After the pipe has been cut
through, the actuator 135 is again positioned between switches 136,
137 so that actuator 160 can be operated. By partial rotation of
gear 121, switch 159 is actuated so that the pressure in the
hydraulic cylinder 125 is equalized and the cutters are retracted
by the linkage. As the cutters are in front of the rams, the
cutters are tilted out of the way of the forward sealing surfaces
of the rams. The rams are then actuated to seal off the inner
casing with respect to the outer casing.
The upper preventer unit 53 shown in FIG. 14 is actually rotated
90.degree. so that the sealing rams 145, 146 are respectively
disposed in one-half of the unit assembly for attachment with the
pipe.
To control the hydraulic power for the cutters, an external conduit
control may be provided by providing a passageway through gear 121.
Gear 121 is, of course, mounted on roller bearings in a cage on the
housing. The passageway is provided by half-moon openings with
depending lip seals which traverse a port in the housing. There
will, of course, be some discontinuity when the lip seals are
displaced from the opening in the housing at the separation plane
between the gear sections, but this does not present any undue
difficulty. More than one external control conduit can be used as
illustrated in FIG. 22.
It is also feasible to enclose the entire operation in a flexible
air chamber to permit operations to be performed in other than a
water environment as shown in FIG. 24.
Rather than operate on pipe strings individually and in sequence,
in FIGS. 25-29, this embodiment contemplates but a single
operation. In this operation, the cutting and sealing unit 205
intermediate of upper and lower sealing assemblies is arranged so
that in a first operation the pipe conduits are severed by a
milling cutter 222. The cutter is retracted and the unit closed off
by a gate ram 227 which permits replacement of the cutter with a
sealing unit. The sealing unit has a ram which traverses and closes
off the unit so that control fluid can be applied to the
pressurized conduit. It is apparent that while the sealing unit is
illustrated as detachable, it can be incorporated in the unit
diametrically to the cutter so that, upon retraction of the cutter,
the sealing unit can be used to close off the bore.
While particular embodiments of the present invention have been
shown and described, it is apparent that changes and modifications
may be made without departing from this invention in its broader
aspects; and, therefore, the aim in the appended claims is to cover
all such changes and modifications as fall within the true spirit
and scope of this invention.
* * * * *