GB2168407A - Grouting the space between a pile and a subsea pile sleeve - Google Patents

Abstract

Grout is supplied to a series of pile sleeves (20) around the base of an offshore structure, using a single umbilical (18) having a connector (38) at its lower end. This umbilical carries grout supply hoses (22) and (23), a packer inflation hose (53) and detector cables (45, 46), and can be moved in turn to each of the pile sleeves (20). At each pile sleeve a coupling (39) can accept the connector (38) (and thus the grout supply hoses, inflation hose and detector cables), whereby to grout up piles within the pile sleeves. Use of a single umbilical (18) and connector (38) avoids need to connect each of the piles sleeves individually to grout supply apparatus above the surface of the water in which the offshore structure stands. Guide means may be provided on the connector (38) and coupling (39) to ensure proper alignment during coupling. These guide means may comprise a helical track and a cooperating abutment (Figure 4), or a guide cone (42, Figure 3) attached to the umbilical. <IMAGE>

Description

SPECIFICATION Grouting the space between a pile and a subsea pile sleeve The invention relates to the installation of piled offshore structures, e.g. platforms or subsea facilities.

Such structures are frequently formed of a lattice steel framework, and are secured by tubular steel piles driven into the sea bed. Until the piles are firmly fixed to the framework, the structure is dependent upon its own weight for stability (against the overturning effect of waves on the upper part of the structure, or current in the case of a subsea facility). Thus, fixing the piles to the framework is on the critical path in the installation of any piled offshore platform or subsea facility.

Piles are usually disposed in clusters at corners of the structure or skirted around the edges of the structure. The piles are secured to pile sleeves, which are in turn attached to the structure. Each pile sleeve is arranged to accept one pile. The pile is secured to its respective sleeve by grout, which is pumped in to fill the annulus between the pile and the sleeve. In order to seal the annulus, inflatable packers are arranged at the bottom of each pile sleeve, so to close the lower end of the annulus.

To demonstrate that all water has been displaced from the pile sleeve by grout, an overflow pipe at the top of the annulus has a grout density detection device. By monitoring the passage of grout through this overflow pipe, operating personnel on the surface can determine when the grout density exiting from the overflow pipe is equal to the grout density being pumped from the surface. This indicates that all the water has been displaced from the annulus, so that the operating personnel can disconnect the supply of grout for reconnection to the next pile sleeve.

Grout monitoring equipment, hoses to inflate the packers, conduits and grout pipes have heretofore been installed on each of the pile sleeves prior to the lattice framework (structure) being submerged beneath the sea; these are complicated, expensive and generally superfluous additions to the structure, bearing in mind that they are used only once during its life.

The invention provides a method of grouting a space between a pile and an underwater pile sleeve, which comprises the steps of lowering a grouting hose terminating in a grouting hose connector from above the surface of the water onto a grout coupling fixed to and communicating with the interior of the pile sleeve, making a fluid resistant connection between the connector and the coupling, and introducing fluid grout from the hose into the space between the pile and the sleeve, in which the flow of grout is subsequently shut off, the connector and the coupling are disconnected, and the connector is then moved and reconnected to another coupling fixed to another underwater pile sleeve, so that the process can be repeated for a second pile.

It is preferred that a grout packer inflation line is formed into an umbilical with the grouting hose, and an inflation line connector at the end of the inflation line is arranged to make sealing connection with an inflation line coupling fixed to the grout coupling aforesaid, whereby grout packer seals for the pile sleeve can be operated down the same umbilical that is used to introduce the grout.

It is also preferred that a grout monitoring cable is formed into a or the umbilical with the grouting hose, and grout monitoring detectors are mounted on the connector to engage a grout overflow pipe fixed to the pile sleeve, whereby to monitor the density of grout exiting from the overflow pipe.

In one preferred form contingency provisions are made through the coupling which carried the grout.

In another preferred form the grouting hose connector has guide means which, in conjunction with corresponding means on the grout coupling, will bring the connector and coupling into radial alignment after the connector has been brought into general alignment axially with the coupling.

In this last mentioned form the guide means may comprise a helical track disposed about a vertical axis on one of the connector and the coupling, and an abutment on the other of the connector and the coupling, movement of the abutment down the track being arranged to bring the connector and the coupling into radial alignment.

Preferably there are two half helixes.

The helix or helixes is or are preferably disposed on a cylindrical inner surface of the connector.

It is preferred that after relative rotational movement has taken place to bring the connector and the coupling into axial alignment, further axial movement is effected to make the grout resistant connection.

Advantageously after initial grouting, fluid is used to purge the coupling of surplus grout, in order to clean the coupling for subsequent secondary grouting.

The invention also provides a connection/disconnection assembly having provision for grouting lines to supply a plurality of pile sleeves at or near the base of an offshore platform.

It is preferred that there is provision for packer seal actuation and or grout monitoring attachments.

The invention includes an offshore platform when piled using the method or the assembly described above.

A specific embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which: Figure I is a perspective view of a lattice steel framework; Figure2 is a schematic diagram of a grouting system; Figure 3 is a schematic diagram of a quick connection assembly for that grouting system; Figure 4 is a sectional view of a different quick connection assembly; and Figures 5to 9 are flow line diagrams showing five stages in the operation of the coupling illustrated in Figure 4.

As shown in Figure 1, a lattice steel framework 10, forming part of an offshore structure, has a multiplicity of pile sleeves arranged in clusters 11 at the corners of its base 12. These pile sleeves are substantially identical, and one such pile sleeve 20 is featured in more detail in Figures 2 and 3.

Near the base of the pile sleeve 20, and as shown in Figure 2, there is a rubber packer 21, which is inflatable to close the bottom of the annulus formed by the pile sleeve 20 and a pile (not shown) extending through that sleeve. Grout can be introduced into the annulus through primary and secondary grout hoses 22 and 23, primary and secondary grout pipes 24 and 25, and primary and secondary manifolds 26 and 27 respectively. A neutrally buoyant umbilical 18 conducts the hoses 22 and 23 from a supply of grout above sea level down to the pile sleeve 20.

The umbilical 18, an upper part 38 of a quick connect/disconnect assembly, and a grout detector guide tu be 37 form a supply unit (shown in more detail in Figure 3) which can be moved between the different pile sleeves 20 in the cluster 11.

For contingency grouting operations, a grout hose 28, a valve 29, and injection couplings 31 can be connected to a diver connection 51 (shown in Figure 3). In the event that grouting cannot be completed via the primary or secondary grout pipes 24 and 25, the diver connection 51 can be supplied with grout from either the primary or secondary grout hoses 22 and 23 by activation of a valve on the upper part 38 ofthe connection assembly. Alternatively, the connection 51 could be supplied from a third grout supply hose, included in the umbilical 18.

A packer inflation hose 33 is protected by a hose conduit 34 alongside the pile 20, and leads to a box 35, where the connection to the packer 21 is made. A packer inflation supply hose 53 is led down the same umbilical 18 which carries the grout hoses 22 and 23.

For contingency packer inflation operations, a diver operated inflation hose 54 is also led down the umbilical 18. This hose can be connected to a diver supply connection 52 (shown in Figure 3) on the upper part 38, to inflate the packer 21 through a hose 55 and the box 35 (shown in Figure 2).

Reverting to Figure 2, a grout overflow pipe 36 is arranged to discharge grout from the annulus when the annulus is full, and grout is in contact with substantially the full depth of the pile sleeve and the pile surface. A relocatable grout detector guide tube 37 (comprising GeigerTubes and nuclear sources, 47 and 48) is arranged to give an indication of the grout density via cables 45 and 46 leading to the surface up the same umbilical 18, which carries the grout hoses 23 and 24, and the packer inflation hose 53.

A deflection elbow is disposed on the grout detector guide tube 37 in order to deflect the grout exiting from the grout overflow pipe 36 away from the quick connect/disconnect assembly.

An hydraulically actuated locking device (not shown) for the upper part 38 of the connect/ disconnect assembly would be provided to secure the upper and lower parts 38 and 39 of that assembly together, and maintain grout seal pressure, during grouting operations.

Upon completion of grouting operations, the locking device would be unlocked to disconnect the parts 38 and 39, so that the umbilical 18 and the upper part 38 could be moved on to the next pile sleeve to be grouted.

The upper and lower parts, 38 and 39 respectively, of the quick connect/disconnect assembly may also be referred to as a connector and coupling respectively, the upper part 38 being a connector attached to the umbilical 18, and the lower part 39 being typical of a coupling fixed to each of the pile sleeves to be grouted.

Figure 3 shows in more detail how the upper and lower parts 38 and 39 of the quick connect/disconnect assembly are arranged for coupling to take place on the pile sleeve 20. A plate 41 fixed to the outside of the pile sleeve 20 is pierced to accept the lower part 39 and a section of the grout overflow pipe 36. The primary and secondary grout pipes 24 and 25 and the conduit 34 for the packer inflation hose 33 are connected to this lower part 39.

A guide cone 42, fixed to the upper part 38 of the quick connect/disconnect assembly, is arranged to guide the assembly (with possible assistance from other secondary guides) into accurate contact with the lower part 39 of the assembly, pipes 24 and 25, and the packer inflation hose 33.

A framework 43 fixed to the upper part 38 supports the grout detector guide tube 37 which has a guide cone 44 disposed to guide the detector over the grout overflow pipe 36. As may be seen in this Figure 3, the upper and lower grout detectors 47 and 48 are connected to lines 45 and 46 respectively. These lines 45 and 46 are led up the same umbilical 18 as the grout supply hoses 22 and 23 and the packer inflation line 53.

In operation, the steel lattice framework 10 is launched and upended (or in the case of a selffloating structure flooded and upended) and thereafter ballasted down to rest with its base on the sea bed.

Atthis time the stability of the framework 10 is dependent only upon its own weight.

Tubular steel piles are then driven down through the pile sleeves 20 and into the sub-sea strata. When the piles have been driven to the calculated depth, the piling device is removed, and the grouting of the piles to the sleeves can commence.

The umbilical 18 and the upper part 38 of the connection can be moved from pile sleeve to pile sleeve in the cluster 11, at each pile sleeve inflating the packer 21, supplying grout down either of the grout hoses 23 or 24 to the annulus between the pile and the sleeve, and monitoring when the annulus is full to overflowing with grout.

An ROV (remotely operated vehicle), either indepedent of or attached to the structure, can be used to locate the connection part 38 at each of the pile sleeves in turn.

Figure 4 illustrates a quick connection grout coupling for use on the offshore structure shown in Figure 1, which has clusters of pile sleeves at the corners of its base, and part of one such pile sleeve (120) is shown in the accompanying drawing.

Attached to the pile sleeve 120 there is a horizontal plate 141 which supports an upwardly-facing male coupling 139 fixed relative to, and spaced apart from, the pile sleeve. The coupling 139 has primary and secondary grout pipes 124 and 125, which are connected to the annular space between the pile (not shown) and the pile sleeve 120. A grout overflow pipe 136 is also connected to the coupling 139. (All these parts are repeated on each of the pile sleeves in the pile cluster).

A downwardly-facing female connector 138 is hung from an umbilical 118, by which the connector can be lowered from a vessel on the surface of the water. The umbilical also includes primary and secondary grout hoses 122 and 123, by which grout can be pumped down from the surface of the water into the pile sleeve 120. The umbilical also has grout monitoring cables leading to a grout detector 137, which is diposed on a grout overflow pipe extension 140 All these items are similar in function to the corresponding items shown in Figure 3. The coupling would additionally have grout packer seal inflation lines as described with reference to Figures 2 and 3, and any other hydraulic/pneumatic lines required.

Following a feature of the present invention, the female connector 138 has a helical guide track 100 disposed on a cylindrical inner surface of that connector. The track 100 is split into two halves, so that a locating pin 101 on the outer surface of the male coupling 139 will bear in the track 100, and then the guide connector 138 clockwise or anti-clockwise into alignment with the slot 102. The locating pin 101 and the sot 102 then guide the connector 138 axially, so as to make a fluid resistant connection between the primary and secondary grout supply hoses 122 and 123, and the primary and secondary grout supply pipes 124 and 125 respectively, (and other lines not shown).

It is a feature of the quick connection grout coupling herein described that the only parts which need to be made to relatively high tolerances are the mating parts of the connector 138. This item is hung from the umbilical 118, and is moved in turn to each of the pile sleeves at each of the pile clusters surrounding the base of the offshore structure. Thus only one component in the system (i.e. the connector 138) needs to be constructed expensively to close tolerances. All the male couplings 139, which are fixed to each of the pile sleeves, can be massproduced economically, since they only have to function once (or at most twice) during the life of the structure.

It will be understood that similar production advantages will occur from the arrangement of parts 38 and 39 of the coupling shown in Figures 2 and 3.

In the unlikely event of the failure of a grout seal after the umbilical 118 and female connector 138 have been moved to another pile sleeve, it may be necessary for the pile sleeve 120 to be regrouted. To permit regrouting, it is desirable to purge the pipes and connections in the couplings 138 and 139 of surplus grout. To this end, a supply of water is provided from hose 151, which is contained within the umbilical 118.

An arrangement of valves to permit primary grouting, subsequent purging, and then secondary grouting is shown in Figure 4; the operation of this arrangement is illustrated in the flow line diagrams of Figures 5 to 9.

The primary and secondary grout hoses have four-way grout valves 152 and 153, respectively, the four openings of which lead from the hoses 122, 123; to overflows 154, 155; to the pipes 124, 125; and to a manifold 156. The purging water supply hose 151 has an open and shut valve 157 leading to the manifold 156.

Below each ofthe four-way valves 152 and 153, and below the manifold 156, there are one-way check valves 158,159 and 160.

As shown in Figure 5, the female connector 138 is lowered towards the male coupling 139 on the pile sleeve with the valve 157 open, and the valves 152 and 153 arranged to connect the manifold 156 with grout piping leading to the pipes 124 and 125, and also supply flushing water to the grout overflow and packer inflation connection.

In Figure 6 the female connector 138 has connected with the male coupling 139, and the valve 157 is closed.

The packer is inflated (e.g. via a nitrogen line, 161) and the valve 152 is turned to permit grout from the hose 122 to reach the grout pipe 124, as shown in Figure 7. Grout is then supplied from above the surface of the water in which the platform stands, to fill the annulus between the pile sleeve 120 and the pile (not shown).

As shown in Figure 8, when grouting from the primary hose 122 is complete (as demonstrated by the grout detector, 137) the supply of grout is diverted through the overflow pipe 154, by turning valve 152.

Next, as shown in Figure 9, the valve 157 is opened automatically as the couplings separate so as to flush the connection and lines with water.

Finally, the female connector 138 is raised, and water is used to clean the zone between the connector and the coupling. Slots 162 allow the water to flush grout away from this coupling.

If the grout in the annulus between the pile sleeve and the pile should leak out of that annulus before setting,then the grouting can be effected again using the secondary supply hose 123, the four-way vale 153, the manifold 156 and the pipe 125. This requires that the connector 138 is returned to the pile sleeve 120, and lowered onto coupling 139. Because of the purging action of the water from supply hose 151, the coupling 139 will be clear of any substantial residue of grout from the primary grouting operation, thus allowing secondary grouting to proceed.

Claims (15)

1. A method of grouting a space between a pile and an underwater pile sleeve, which comprises the steps of lowering a grouting hose terminating in a grouting hose connector from above the surface of the water onto a grout coupling fixed to and communicating with the interior of the pile sleeve, making a fluid resistant connection between the connector and the coupling, and introducing fluid grout from the hose into the space between the pile and the sleeve, in which the flow of grout is subsequently shut off, the connector and the coupling are disconnected, and the connector is then moved and reconnected to another coupling fixed to another underwater pile sleeve, so that the process can be repeated for a second pile.

2. Method as claimed in claim 1 in which a grout packer inflation line is formed into an umbilical with the grouting hose, and an inflation line connector at the end of the inflation line is arranged to make sealing connection with an inflation line coupling fixed to the grout coupling aforesaid, whereby grout packer seals for the pile sleeve can be operated down the same umbilical that is used to introduce the grout.

3. Method as claimed in claim 1 or claim 2 in which a grout monitoring cable is formed into a or the umbilical with the grouting hose, and grout monitoring detectors are mounted on the connector to engage a grout overflow pipe fixed to the pile sleeve, whereby to monitor the density if grout exiting from the overflow pipe.

4. Method as claimed in any of the preceding claims in which contingency provisions are made through the coupling which carried the grout.

5. Method as claimed in any one of claims 1 to 4 in which the grouting hose connector has guide means which, in conjunction with corresponding means on the grout coupling, will bring the connector and coupling into radial alignment after the connector has been brought into general alignment axially with the coupling.

6. Method as claimed in claim 5 in which the guide means comprise a helical track diposed about a vertical axis on one of the connector and the coupling, and an abutment on the other of the connector and the coupling, movement of the abutment down the track being arranged to bring the connector and the coupling into radial alignment.

7. Method as claimed in claim 6 in which there are two half helixes.

8. Method as claimed in claim 6 or claim 7 in which the helix or helixes is or are disposed on a cylindrical inner surface of the connector.

9. Method as claimed in any one of claims 5 to 8 in which, after relative rotational movement has taken place to bring the connector and the coupling into axial alignment, further axial movement is effected to make the grout resistant connection.

10. Method as claimed in any one of the preceeding claims in which, after initial grouting, fluid is used to purge the coupling of surplus grout, in order to clean the coupling for subsequent secondary grouting.

11. A connection/disconnection assembly having provision for grouting lines to supply a plurality of pile sleeves at or near the base of an offshore platform.

12. Assembly as claimed in claim 11 and having provision for packer seal actuation and or grout monitoring attachments.

13. A method substantially as hereinbefore described with reference to the accompanying drawings.

14. An assembly substantially as hereinbefore described with reference to and as shown in Figures 2 and 3 of the accompanying drawings.

15. An offshore platform when piled using the method of any o.ne of claims 1 to 10 or 12, or the assembly of any one of claims 11, 13, or 14.

15. An assembly substantially as hereinbefore described with reference to and as shown in Figure 4 of the accompanying drawings.

16. An offshore platform when piled using the method of any one of claims 1 to 10 or 13, orthe assembly of any of claims 11,12, or 15.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1 and 11 to 15 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows:

1. A method of grouting a space between a pile and an underwater pile sleeve, which comprises the steps of lowering a grouting hose terminating in a grouting hose connector from above the surface of the water onto a grout coupling fixed to and communicating with the interior of the pile sleeve, making a fluid resistant connection between the connector and the coupling, and introducing fluid grout from the hose into the space between the pile and the sleeve, in which the flow of grout is subsequently shut off, the connector and the coupling are disconnected, and the connector is then moved and reconnected to another coupling fixed to another underwater pile sleeve, so that the process can be repeated for a second pile; and in which there is secondary grouting means, so that the connector can be moved back to a previously grouted pile sleeve to regrout that pile sleeve if necessary.

11. A connection/disconnection assembly having provision for grouting lines to supply a plurality of pile sleeves at or near the base of an offshore platform, and having provision for grout monitoring attachments.

12. A method substantially as hereinbefore described with reference to the accompanying drawings.

13. An assembly substantially as hereinbefore described with reference to and as shown in Figures 2 and 3 of the accompanying drawings.

14. An assembly substantially as herein before described with reference to and as shown in Figure 4 of the accompanying drawings.