Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the grouting of offshore
structures.
2. Description of the Prior Art
Offshore structures or rigs have come into increasing
use in recent years ts support platforms for drilling
of oil and gas wells and for producing oil and gas from
such wells. Such structures may be erected in water
from comparatively shallow depths up to several hundred
feet deep A variety o~~forms of structure and methods
of construction of such platforms have been utilized.
One such method which has been found to be particularly
desirable in deep water is that which is illustrated,
for example, in U. S. Patent No. 3,209~544 to Borrmann,
3~ in which the legs of the structure are fabricated and
assembled on shore~ The legs are hollow, and may be
sealed to make the structure buoyant, 50 that it can be
towed out to the desired offshore location. Valves in
... .. . ..... . .. ~ .. . . _
- : ~
~ .
.~; .
1~L3S~64
1 the legs are opened to allow flooding with sea water,
so that the leg structure will sink in a vertical
- position and settle onto the bottom. As the legs sink
they fill with water up to the water level of the sea.
It will be appreciated that the legs will sink into the
ocean bottom a distance dependent upon the weight of
the structure and the softness of the ocean bed.
A platform which is built only on such legs would have
a high degree of instability, particularly in heavy storms.
It has, therefore, been the practice to more rigidly connec~;
the structure to the ground by driving hollow steel pilings
down through the legs, which then become jackets for the
- pilings.
When the piling has been fully driven (usually to
refusal~, it has been the practice to fill the annulus
between the piling ànd the jacket with a grouting material
which solidifies in place. This increases the rigidity
and, therefore, the strength of the structure by increasing
the surface area and strength of the connection between
the piling and the jacket. It also helps to keep out
water so as to prevent corrosion of the piling.
Various methods have been utili~ed for grouting
such structures. One method, as shown in the aforesaid
Borrmann patent, for example, requires the use of a
seal member at the bottom o~ the annulus. In this
method the grouting material is pumped-into the bottom
3~ of the annulus and rises upwardly therein to the top.
This method usually requires the use of divers, and in
addition, it often fails to produce fully satisfactory
~3
.
11~5~64
1 results because water cannot be effectively excluded
from the annular space so that the grouting material
becomes diluted and difficult to set.
Evans et al, in U. S. Patent NQ . 3,492,824, de-
scribe a method comprising injecting air into the top
of the annulus to expel water through a nipple at the
bottom of the annulus, and then injecting grouting
material through the bottom nipple. The grouting
material is supposed to rise up through the annulus to
above the water line, displacing air out the top. As a , ,
practical matter such a system would be very unsatis-
factory. The ocean bed is normally soft and porous at
the bottom of the jacket so that as soon as enough
grouting material is pumped in to overcome the hydraulic
head of the overlying sea water, the grouting materia
would begin to run out the bottom of the jacket and
would be lost. Thus, it would be necessary to utilize
2~ some kind of seal or closure at the bottom of the
annulus to hold the grouting in.
Evans et al also disclose a method whereby air is
injected into the nipple at the bottom of the annulus
to drive the water upwaraly through the annulus out the
top. It is apparent that such a system would be ex~
tremely inefficient in expelling water, since the air,
being lighter, will rise up through the water. The
same problem of losing grout out the bottom would also
3~ exist in this method.
Blount et al in British Patent 1,307,181, issued
February 14, 1973, disclose another grouting system in
which the grouting material is injected through nipples
y
~135~64
1 at the bottom of the annulus. Blount uses water to wash out
mud from the location of Bount's injection nipples upwardly;
but, Blount makes no attempt to remove water or mud from
below the injection point. Furthermore, Blount's annulus is
filled with water at the start, which must be expelled
upwardly by the rising grouting ma.erial. Thus a large
excess of grouting material would be necessary in order to
insure that all of the water is expelled out of the top of
the annulus.
Olsen and Bassett disclose, in their United States
Patent Re. 28,232, a reissue of United States Patent No.
3,601,999, a systPm which avoids many of the problems en-
countered in other grouting systems. U. S. Patent No.
3,832,857 to Bassett is an improvement over that system.
See also:
U. S. Paten~s
1,013,758 - Fox et al, issued January 2, 1919, for "METHOD
OF AND APPARATUS FOR APPLYING PROTECTING COVERING TO PILES":
1,084,063 - Bignell, issued January 13, 1914, for "MEANS FOR
FORMING UNDERGROUND FOOTING FOR PILES AND CAISSONS":
1,729,422 - Gleasner~ issued September 24, 1929, for "METHOD
OF CLEARING AND FILLING TUBULAR PILES FOR FOUNDATIONS";
- 1,753,440 - Miller, issued April 8, 1930, for "METHOD OF
DRILLING ~ELLS IN GAS FORMATIONS";
3,011,547 - Holbert et al, issued December 5, 1961, for
"METHOD OF PREVENTING LOSS OF GASEOUS DRILLING FLUID";
3,100,525 - Smith et al, issued August 13, 1963, for
"CEMENTING":
3,114,419 - Perry et al, issued December 17, 1963, for
"METHOD FOR POLYMERIZING LIQUID RESIN-FORMING MATERIALS";
3~
3,152,641 - Boyd, issued October 13, 1964, for "l~ETHOD FOR
~POLYMERIZING RESIN-FORMING MATERIALS IN SUBTERRANEAN AREAS";
3,187,513 - Guild, issued June 8, 1965, for "METHOD OF
DRIVING PILES";
~. ' '
1~3~64
3,196,946 - Lauffer, issuecl July 27, 1965, for "AIR METHOD OF CEMENTING
WELLS";
3,213,629 - Manning, issued October 26, 1965, for "APPARATUS AND METHOD
FOR INSTALLATION OF A PILE-JACKET ASSEMBLY IN A MARINE BOTTOM";
3,597,930 - Rochelle, issued August 10, 1971, for "METHOD AND APPARATUS
FOR REINFORCING IN SITUS IN PILE CASING";
3,811,289 - Bassett, issued May 21, 1974, for "MElHODS OF GROUTING OF
OFFSHORE STRUCTURES"; and
3,878,687 - Tragesser, Jr., issued April 22, 1975, for "GROUTING OF
OFFSHORE STRUCTURES".
FOREIGN PATENTS
Austrian Patent No. 23,039 - Josef Vincent Brejcha, issued February 10,
1906, for "FLUSH JOINT FOR BORE HOLES";
Swiss Patent No. 180,901 - Eugene Frote, issued February 1, 1936 for
"PROCESS FOR THE CONSTRUCTION OF EXPANDED BASE PILES, CAST IN THE GROUND";
German Patent No. 286,333 - August Wolfholz Preszzementbau, issued April 1,
1913, for "PROCESS FOR CASTING CONCRETE PILES IN THE GROUND, BY MEANS OF A
CASING AND COMPRESSED AIR;" and
British Patent No. 674,809 - Lionel Ignacio Viera Rios, issued July 2, 1952,
for "METHOD OF AND APPARATUS FOR SINKING CONCRETE, CEMENT OR THE LIKE PILES
IN GROUND HAVING AN EXCESSIVE MOISTURE CONTENT".
The present invention is an improvement over the prior art patents
for use with submerged piles for offshore rigs set in deeper water.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is
provided a method of testing an offshore structure having at least one
submerged supporting member, the member including a substantially vertically
extending tubular jacket and a piling in said jacket having an outside
diameter smaller than the inside diameter of the jacket whereby a space is
formed between the inside of the jacket and said piling; said space having
a packer at its upper end and a packer at its lower end, wherein the space
between the packers is initially filled with water and wherein a first
fluid conductive line extends from the surface of the water to and in fluid
flow communication with the upper end of the jacket below the upper packer
and a second fluid conductive line extends from the surface of the water to
and in fluid flow communication with the lower end of the jacket above the
lower packer, said method comprising the steps of:
113~6~6~
A. setting the upper and lower packers;
B. testing the upper packer through the use of compressed fluid supplied
through one of the lines to determine if the upper packer is sealed against
the piling.
The procedure for introducing fluid grouting material from
surface apparatus through the dual lines into the annular space is
dependent on testing the integrity of the seal of the packers with the
jacket and the piling. The annular space is then filled with grouting
material from the surface apparatus through the use of the dual lines.
Also, the grouting material introduced into the annular space may be
subjected to increased pressure after filling to aid in forming a bond
with the piling and the jacket.
BRIEF DESCRIPTION OF THE DRAWINGS
For a further understanding of the nature and objects of the
present invention, reference should be had to the following detailed
description, taken in conjunction with the accompanying drawings, in
which like parts are given like reference numerals and wherein:
Figure 1 is an elevational view showing a typical pin pile
installation of legs of an offshore rig on the sea bed;
Figure 2 is a side cross-sectional view of one of the legs of
Figure 1 taken along section lines 2-2 of Figure l;
--7--
ll~S~64
Figure 3 is a top cross-sectional view of the legs
of Figure 2 taken along section lines 3-3 of Figure l;
Figure 4 is a semi-schematic view of apparatus
suitable for practicing the preferred embodiment of the
method of the invention;
Figure S is an enlarged vertical section view of one
of the pin piles of the structure of Figure 1, showing
the method step of expelling water from the annular
chamber between the jacket and the pile, the chamber
being bounded at its upper and lower ends by packers;
Figure 6 is an enlarged vertical sectional view of
one of the pin piles of the structure of Figure 1, show-
ing the grouting material in place;
Figure 7 is an enlarged vertical sectional view of
one of the pin piles of the structure of Figure 1, show-
ing a failed upper packer and grouting material in place;
and
Figure 8 is an enlarged vertical sectional view of
one of the pin piles of the structure of Figure 1, show-
ing a failed lower packer and grouting material in place.
DESCRIPTION_OF THE PREFERRED EMBODIMENT
--INTRODUCTION--
The preferred embodiment of the present invention
may be used to fill annular spaces with fluid grouting
material wherein the annular space is entirely submerged.
A particularly important area of the application of the
3a present invention involves the grouting of submerged
support pile structures, such as pin piles, for main legs
of offshore rigs. A set of such pile structures is
1135~6~
1 usually connected to the lower end of a hollow main leg
of an offshore rig to structurally support the lower end
of the leg. Each such pile structure comprises a hollow
jacket with a pile driven ~hrough the center of the
jacket, forming an annulus. Lower and upper packers are
used to connect the jacket with the pile. The method and
apparatus are used to fill the submerged annular space
formed by the pile, the jacket and the pair of packers
with fluid grouting material.
However, it should be realized that the present ~ ~-
invention could be applied to, for example, any offshore
structure wherein grouting is to be accomplished in an
annulus between two sealed positions.
-STRUCTURE AND ITS METHOD OF USE-
A typical deep water offshore structure 10,
such as is used in the oil and gas industry for offshore
drilling and production, is shown in Figures 1-3. The
structure 10 as shown is only the base portion which is
being installed on the sea bed.12, prior to providing the
base portion with the usual platform and superstructure
(not shown). The structure 10 includes a plurality of
supporting legs 11, each in the form of a tubular jacket
13 which extends downwardly from above the water.line 14
into.the sea bed 12. The several leg jackets are secured
together by cross members 15 and diagonals 16 in a conven-
tional manner. As is known, the sea bed 12 is usually
3~ comparatively soft and porous, and in many instances the
structure 10 will sink of its own weight until the jackets
13 sink many feet, such as, for example thirty feet, into
f~
~135064
1 the sea bed. Each jacket 13 is connected by shear plates
18 to pin piles 19 by welding or other means well known
in the art prior to placing jacket 13 on the sea bottom
12. Pin piles 19 have a jacket 21 (Figure 2) and may
have a funnel top 23 with upper open end 30. Jackets 21
inlude flznges 22 mounted on the exterior of ja~kets 21.
Flanges 22 are mounted on jacket 21 by welding or other
suitable means well known in the art. Bands 24 are
connected by tension or welding or other suitable means
to pin piles 19. Bands 24 are also connected by welding . ?
or other means to tubular jackets 13. Pin piles 19 do
not usually extend to the surface 14 of the water after
the structure 10 is set on the bottom 12.
When the structure 10 is properly placed, pilings 17
are driven through the jackets 21 into the sea bed,
usually to the point of refusal, to provide a final
support for the platform. As shown, the pilings 17 are
normally of tubular steel, and are usually of at least
one pipe size smaller than the size of the jackets 21, so
that an annular space 20 exists between each piling and
its surrounding jacket. The annular space 20 is not, of
course, uAiform, since no means are used to center the
piling in the jacket. On the average, however, the
annulus will have a radial thickness of from one inch to
two and one-half inches depending upon the si~e of the
installation. A lower packer 25 and an upper packer 27
are located within each annular space 20. Packers 2S, 27
are usually of the inflatable type, such as Lynes Types
"A" and "SR" manufactured by Lynes Construction Systems
Division (Houston, Texas) of Baker Oil Tools, Inc. Each
35~6~
1 set of packers 25, 27, when set by inflation, usually
provide a pressure tight seal to the piling 17 and the
jacket 21 at the lower portion 31 and upper portion 33 of
annular space 20, thus forming annular chamber 29. When
the packers 25, 27 provide a pressure tight seal, annular
chamber 29 must be filled with grouting material to
attain leg rigidity sufficient to withstand tides, storms,
ocean currents and the like and also to protect the
piling 17 and the inside of the jacket 21 against corrosion
by sea water.
A more detailed view of the structure of pin piles
19 is given in Figure 5. Each pin pile 19 includes a
pipe 35 in fluid communication with the interiors 36) 38
of packers 25, 27 respectively through check valves 37,
39 respectively. Pipe 35 is connected to check valve 37
through chamber 53. Check valves 37, 39 include springs
41, 43 respectively, supporting balls 45, 47 respectively,
against orifices 49, 51 respectively.
Chamber 53 includes seal 55 sealing the section of
pipe 35 extending upwardly from chamber 53 to the upper
end of chamber 53. Chamber 53 further includes orifice
54 and grout shear plug 57 which extends over orifice 54.
The bond of grout shear plug 57 to the interior of orifice
54 may be of any suitable material capable of shearing
from the interior at a predetermined differential pressure
between annular chamber 29 and chamber 53 above that
needed to set packers 25, 27, such as, for example, in
the range of 250 to 800 psi.
Each pin pile 19 further includes a pipe 59 in fluid
flow communication with annular chamber 29 in the upper
portion 33 of annular space 20.
i~ 35~f~4
1 Pipes 35, 59 extend upwardly from pin piles 19 to
the surface 14 of the water where they are connected to a
suitable source 38 (Figure 4) of air gas grout, and
packer inflating fluid.
One form of apparatus 38 which has been found suit-
able for performing the method of this invention is shown
in somewhat schematic form in FIG. 4. In this structure
two pressure tanks 30', 32' are provided for storage of
dry cement. These pressure tanks 30', 32' may, for
example, be of the type provided with an air slide bottom, !
as shown in U. S. Pat. No. 2,609,125 to Schemm or as
shown in U. S. Pat. No. 2,934,223 to Scruby et al. In
such structure, dry cement is put into the tanks and lies
on a porous sloped bottom, and air flowing through the
bottom fluidizes the material in the tank to cause it to
flow down the slope. In the structure shown, air for
such fluidizing is provided by a low pressure air compres-
~ sor 34' from which air passes through conduit 36', 38' to
tanks 30', 32' respectively. Valves 40', 42' are provided
to control flow to one or the other of the tanks 30',
32'.
Fluidized cement is carried from the pressure tanks30', 32' through conduits 44l, 46'. Flow through conduits
44', 46' is controlled by valves 48', 50'. The fluidized
cement flows from one of the tanks 30', 32' at a time to
a surge tank 52' provided with a suitable dry material
3~ valve 54' at its lower end. The valve may, for example,
be of the type shown in U. S. Pat. No. 2,858,966 to
Pfening. When the valve 54' is opened the dry cement
~/2_
~r` )
li35(~69~
falls into a hopper 56' which is connected at its lower
end to a mi~ing chamber 58'. A nozzle 60' extends into
the mixing chamber, perpendicular to the outlet of the
hopper 56' and coaxially with a mixed cement line 62'.
Water is provided to the nozzle 60' by means of a suitable
pump 64' which takes suction from a water storage tank
66' through a water line 68'. The water tank may be
provided with any convenient gauge so that the amount of
1~ water used can be accurately determined.
It will be appreciated that cement falling from the
hopper 56' into the mixing chamber 58' is thoroughly
admixed into water sprayed from the nozzle 60'. The
mixture passes through the line 62' into a slurry tub
70'. A suitable pump 72' takes suction from the slurry
tub 70' through a line 74' and pumps the fluid grouting
material into manifold 89' through a pipe or hose 76',
which is provided with a check valve 86' to allow flow
only toward the manifold 89'. Centrifugal pumps are
satisfactory in many instances, but where high pressure
is required, as in deep water installations, a reciprocating
pump may be more desirable.
To provide high pressure, high volume gas for ex-
pelling water from the annulus and for the grouting
operation, a high pressu~re, high volume air compressor
78' is provided. Air is usually used for the gas. The
air compressor 78' should have an outlet pressure and
3~ flows suffici~nt to force water from annular chamber 29
located hundreds of feet below the surface 14 of the
water through pipes 35 or 59 to the surface 14, such as,
~ /3--
1~35064
for example, outlet pressures of 200 to 600 psi with
volumes of 500 to 250Q c.f.m.
Air compressor 78' provides air through a conduit
80', fitted with a suitable valve 8~', a pressure gauge
84', and a bleed line 83' having a valve 35' therein.
Valve 82' permits the flow of air into conduit 87' to
manifold 89'. The pressure gauge 84' is preferably one
which reads in feet of sea water, for a purpose which
will hereinafter be explained.
The inflation of packers 25, 27 with air as the , ,
inflating fluid, such as air from conduit 87', is well
known in the art. However, should liquid or other inflat-
ing fluid, such as, for example, water, be desired,
conduit 98' may be provided to connect water tank 66'
with booster pump 90'. The outlet of booster pump 90' is
connected to manifold 89' by conduit 92' with pressure
gauge 55' to indicate fluid pressure.
Liquid receiving tank 111' is also connected by pipe
110' to manifold 89'. Tank 111' includes pressure gauge
117', level gauge 115' and drain valve 113'. Drain valve
113' is connected to tank 111' by pipe 119'.
Manifold 89' includes conduits and pipes 91', 93',
95', 96', connecting manifold 89' to conduit 87', pipe
76', conduit 92', and pipe 110' respectively. Manifold
89' also includes outlet pipes 101' and 103'. Valve 97',
99', 105', 107', 109', and 106' connect-conduit and pipe
3~ 95', 91', 91', 93', 93', 96' respectively to conduit and
pipe 91', 101', 103', 101', 103', 107' respectively.
outlet pipes 101', 103' may be connected to a set of the
_ /~
~135~6~
1 pipes 35, 5g respectively. Conduit 107' is connected to
conduit 101'.
In the discussion infra of the method for filling
the annular chambers 29 with fluid grouting material,
only the filling o~ a single annular chamber 29 will be
discussed. However, several or all of the annular
chambers 29 may be set simultaneously or sequentially
without departing from the spirit of the invention.
In the practice of the preferred embodiment of the
method of this invention, the packers 25, 27 are set by
inflating them through fluid from pipe 35. Inflating
fluid under sufficient pressure to overcome the spring
pressure of check valves 37, 39 is introduced by the
appropriate valve setting into into conduit 91' of mani-
fold ~9' from either conduit 92' or conduit 87'. Valve
99' permits the flow of the inflating fluid from conduit
91' to outlet conduit 101' and thence through pipe 35.
The grout shear plug 57 prevents fluid communication
between chamber 53 and annular chamber 29 through orifice
54 while the packers 25, 27 are being set. The inflating
fluid is usually introduced to slowly pressure up the
interiors 36, 38 of packers 25, 27 respectively. After
the packers 25, 27 seal against piling 17, the fluid
inflate pressure is raised until a differential pressure
(the difference in pressure between the pressure inside
pipe 35 and the pressure on the lower portion 31 of
annular space 29) is reached sufficient to shear the
plug 57 from orifice 54, such as in the range of 250 to
800 psi. At this pressure, the shear plug 57 will shear
~- s - ~
1135064
loose from orifice 54. After the plug 57 is sheared,
fluid communication between pipe 35 and annular chamber
2g through orifice 54 will occur. This will be indicated
by fluid circulation between pipes 35 and 59. A sudden
drop in pressure may also be detected by gauge 55'. The
drop in pressure will cause check valves 37, 39 to close,
trapping inflation fluid under pressure in the interiors
36, 38 of packers 25, 27, thus setting the packer 25, 27.
Should the pressure fail to drop or circulation appear,
0 the lower packer 25 has probably failed to form a seal
with jacket 21. Filling of annular space 20 through pipe
59 under such circumstances is discussed infra. Should
the pressure of inflate fluid fail to rise beyond the
back pressure of check valves 37, 39, the upper packer 27
has probably failed to form a seal with ~acket 21.
Filling of annular space 20 through pipe 59 under such
circumstances is discussed infra.
After packers 25, 27 are detected as set, an attempt
is made to expel water trapped ln the annular chamber 29.
o Valves 82', 106' are opened; valves 95', 99' 107', lO9'
and 106' are closed. Air is then forced from compxessor
78' through pipe 59 to expel water trapped in the annular
chamber 29 out through orifice 54 and through pipe 35.
As the air is introduced into annular chamber 29, the
amount of water flowing through pipe 35 may be measured
through the level gauge 115' of receiving tank lll' to
test the integrity of packer 27. If little or no water
is expelled from pipe 35, packer 27 is not forming a seal
with piling 17. If an amount of water corresponding to a
0 _ l6-
.. . `f ~ . ,
1135~tj4
significant portion of the volume o~ water that should be
contained in annular chamber 29 is entrained by the large
volume of air and conveyed to tank 111', packer 27 is
sealing against piling 17. Alternately pressure gauge
84' may be monitored in feet of sea water to deter~ine if
a pressure exists in the annular chamber 29 sufficient to
overcome the hydrostatic head pressure at lower portion
31. It is therefore convenient for pressure gauge 84' to
have a scale graduated in feet of water. Care must be
taken to maintain the pressure in annular chamber 29 at
the approximate pressure of the water previously in the
chamber 29 during the expelling of water from chamber 29.
A sudden drop in pressure might cause collapse of either
or both packers 28, 27 and also might cause collapse of
jacket 21 or piling 17.
The air pressure on the downstream side of the water
may be controlled to maintain a desired differential pres-
sure between the outlet of compressor 78' and the pressure
in tank 111' if desired. This pressure may be controlled
'0 by manipulating valve 113' or another valve (not shown)
attached to,the upper par~ of tank 111' if the dual use
of valve 113' for drainage and air venting makes the use
of a single valve inappropriate or if water interferes
with the venting.
If packer 27 is found to be sealing against piling
17 (Figure 5~, the method further includes the step of
attempting to continue to raise the pressure in annular
chamber 29 by introducing additional air through pipe 59.
If the introduction of air through pipe 59 fails to cause
the pressure to rise in annular chamber 29 as measured by
1135~64
gauge 84', then packer 25 is not sealing against piling
17. If the introduction of air through pipe 59 causes
the pressure to rise in annular chamber 29, then packer
25 is sealing against piling 17. ., If both packers 25, 27 are sealing against piling
17, then the method includes the steps of:
(1) Bleeding air from annular chamber 29 through
pipe 59 to slowly lower the pressure in annular chamber
29 to a value substantially equal to the external hydros-
0 tatic head pressure on annular chamber 29 (the sudden re- ' ?:
duction of air pressure in line 59 before the introduction of
grout into annular-chamber 23 to compensate for the reduction
might cause damage to either or both packers 25, 27 or piling
17 or jacket 21 because of the large differential pressure be-
tween annular chamber 29 and the hydrostatic head);
(2) Opening valve 107' and closing valve 106';
(3) Flowing fluid grouting material into annular
chamber 29 through pipe 76', manifold 89', and pipe 35
until annular chamber 29 is filled and grout returns to
~0 the water surface 14 through pipe 59. Detection of the
return may be made by sight glass, the outlet of valve
85' or other suitable means. The fluid grouting material
is typically pumped into annular chamber 29 while gradually
releasing the air in annular chamber 29 through pipe 5g
to control the pressure in annular chamber 29 at approxi-
mately the pressure of the external hydrostatic head
pressure on annular chamber 29;
(4) After grouting material has filled annular
chamber 29 and re~urns through pipe 59 (Figure 6), addi-
tional air is introduced to cause pressure to be exerted
D tf ~
' ` f`~
:~1 3SU~4
on the grouting material in excess of the external hydros-
tatic head pressure on annular chamber 29. This causes a
better bond of the grouting material with piling 17 and
jacket 21.
If packer 27 is found not to be sealing against
piling 17 (Figure 7) or jacket 21, instead of using the
above steps, the method includes the step of employing
conventional grouting techniques to seal annulus 20.
See, for example, U. S. Patent 3,209,544. ~alves 106',
97', 99', 105', and 109' are closed. Valve 107' is `
opened. Grouting material is pumped through pipe 35 into
annulus 20 through orifice 54. A television camera,
diver or other means well known in the art may be employed
to monitor the upper opening 30 of annulus 20 to detect
the emergence of the grouting material as annulus 20
fills with grout. As an alternate to monitoring of upper
opening 30 for grout returns, after annulus 20 is filled,
a volume of grouting material substantially greater than
the theoretical volume of annulus 20 may be introduced
~0 into annulus 20 ~hrough pipe 35 and permitted sufficient
~^ time to set Then, after closing valve 107' and opening
valve 105', air can then be introduced into line 59. If
a pressure of the air is greater than the hydrostatic
head, the annulus 20 may be presumed to be substantially
full of grout. Also, pipe 59 may be used in the same
manner to introduce the grouting material into the annulus,
especially if grout shear plug 57 has not sheared because
packer 27 is not sealing against jacket 21.
If packer 25 is found not to be sealing against
piling 17 (Figure 8) of jacket 21, the method includes
_/q _
( s
~1350~ ~
the step of employing pressure grouting techniques to
seal annulus 20. See, for example, U. S. Patent Re.28,232.
Valves 97', 99' and 107' are closed. Valves 105', 106'
and 109' are opened. Air is then introduced into pipe 59
to force the water out of annulus 20 through 35 to tank
111'. ~alve 106' is closed after the water is expelled.
Alternatively, valve 106' may be closed and the water
forced out the bottom of annulus 20 as disclosed in- U. S.
Patent Re.28,232. Grouting material is then introduced
i through pipe 59 while maintaining pressure in annulus 20 .
through pipe 59 approximately equal to the hydrostatic
head pressure on annulus 20. However, because only one
line is available for both maintaining air pressure and
introducing grout, the method of introducing air and
grout is somewhat dependent on the manifold 89'. If
grout and air cannot be introduced simultaneously, grout-
ing of the annulus 20 may be accomplished by alternately: -
tl) introducing grout, and
(2) intro ucing or venting air in pipe 59 to main-
~0 tain hydrostatic pressure until the portion of annulus 20
- below the lower side of packing 25 is substantially full
of grout and sets.
Also, alternately, after air is introduced into
annulus 20, quick setting cement or other suitable grout-
ing material may be introduced into the lower portion of
annulus 20 through pipe 59 or 35 to form a plug which may
be permitted to set while maintaining air pressure through
pipe 59. I grouting material and air are both intro-
duced through pipe 59, the formation of a grout plug at
the bottom of annulus 20, in a combination with packer 27
1135~64
sealing against piling 17, permits the use of the steps
set out for packers 25, 27 both sealing against piling
17. However, if pipe 35 is used to introduce grout into
annulus 20 to form the grout plug or if plug 57 has not
sheared, then pipe 35 probably will be unable to pass
further grout after the initial grout plug is formed. In
this instance, pipe 59 would be used to supply air to
maintain pressure while permitting the subsequent flow of
grouting material into annulus 20 as previously described
in this paragraph.
Although the apparatus and method described in
detail supra has been found to be most satisfactory and
preferred, many variations in structure and method are
possible. For example, any manifold arrangement permitting
either air or grouting material to flow in pipe 59 and
grouting material to flow in pipe 35 may be used. Also
any gas may be used. Moreover, a manifold may be provided
for each set of pipes 35, 59 or the pipes may alternately
be connected to the manifold.
'0 ~he above are exemplary of the possible changes or
- variations.
Because many varying and different embodiments may
be made within the scoEe of the inventive concept herein
taught and because many modifications may be made in the
embodiment herein detailed in accordance with the descrip-
tive requirements of the law, it should be understood
that the details herein are to be interpreted as illus-
trative and not in a limiting sense.
What i5 claimed as invention is:
