METHOD OF INSULATING AN OBJECT

Abstract

A method of insulating an object, such as a pipe for carrying crude oil or natural gas, includes providing an insulating fluid comprising a base fluid and a viscosifying agent, wherein the viscosifying agent comprises silicon dioxide. The base fluid is optionally a non-aqueous base fluid. The method further includes the steps of adding the insulating fluid to a container, and placing the object in the container. The object which is insulated can be located remotely or subsea.

Claims

1. A method of insulating an object, the method comprising the steps of: providing an insulating fluid comprising a base fluid and a viscosifying agent, the viscosifying agent comprising silicon dioxide; adding the insulating fluid to a container; and placing the object in the container.

2. A method according to claim 1, further including the step of the insulating fluid forming a paste.

3. A method according to claim 1, further including heating the insulating fluid before adding the insulating fluid to the container; and allowing the insulating fluid to cool to form a paste before placing the object in the container.

4. A method according to claim 1, wherein the insulating fluid further comprises a wax.

5. A method according to claim 4, wherein the wax has a melting point of from 25 to 85? C.

6. A method according to claim 4, wherein the insulating fluid comprises from 10 to 30% wt/wt of wax.

7. A method according to claim 4, further including heating the insulating fluid to melt the wax and, after the step of adding the insulating fluid to the container, allowing the insulating fluid to cool to form a paste.

8. A method according to claim 1, wherein the step of placing an object in a container is before the step of adding the insulating fluid to the container.

9. A method according to claim 3, further including the step of inverting the container after the step of allowing the insulating fluid to cool to form a paste, the step of placing the object in the container involving lowering the container over the object so that the insulating fluid is in contact with the object.

10. A method according to claim 1, wherein the object is located remotely or subsea, the object being a pipe for carrying crude oil or natural gas.

11. A method according to claim 1, wherein the container has a three-dimensional shape corresponding to a shape of the object.

12. A method according to claim 1, wherein the insulating fluid is a non-Newtonian fluid.

13. A method according to claim 1, wherein the insulating fluid is a thixotropic fluid.

14. A method according to claim 1, wherein the viscosity of the insulating fluid is from 2,000 to 10,000 centipoise at a shear rate of 1.1 s.sup.?1 or from 400 to 1,500 centipoise at a shear rate of 75.4 s.sup.?1.

15. A method according to claim 1, wherein the base fluid is non-aqueous and comprises an oil.

16. A method according to claim 1, wherein the base fluid is non-aqueous and comprises a siloxane.

17. A method according to claim 1, wherein the insulating fluid comprises from 40 to 70% vol/vol base fluid.

18. A method according to claim 1, wherein the density of the base fluid is from 0.7 to 1.5 g/cc.

19. (canceled)

20. A method according to claim 1, wherein the insulating fluid comprises from 3 to 10% vol/vol viscosifying agent.

21. A method according to claim 1, wherein the insulating fluid is a stable mixture in the temperature range of from ?10 to 100? C.

22. A method according to claim 1, wherein the insulating fluid further comprise microspheres.

23. (canceled)

24. A method according to claim 22, wherein the insulating fluid comprises from 25 to 60% vol/vol microspheres.

25. A method according to claim 1, wherein the thermal conductivity of the insulating fluid is from 0.08 to 0.1 W/m K.

Description

[0059] An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:

[0060] FIG. 1 is cross-sectional view of an object, container and insulating fluid according to an embodiment of the present invention;

[0061] FIG. 2 is a perspective view of an object and a container;

[0062] FIG. 3 is a perspective view of a connector for attaching together two containers;

[0063] FIG. 4 is a perspective view of a container; and

[0064] FIG. 5 is cross-sectional perspective view of an object, container and insulating fluid.

[0065] FIG. 1 shows an object 10, an insulating fluid 12 in the form of a paste and a container 14. The object 10 is a pipe with a bore 16. FIG. 1 also shows a connector 20.

[0066] The container 14 is made of high density polyethylene (HDPE). In an alternative embodiment the container 14 is made of polypropylene or polytetrafluoroethylene (PTFE). Other similar materials may be used.

[0067] The insulating fluid 12 comprises a base fluid and a viscosifying agent, the viscosifying agent containing silicon dioxide. The insulating fluid 12 shown in FIG. 1 occupies a space (not shown) between the pipe 10 and the container 14.

TABLE-US-00001 TABLE 1 shows typical viscosities of the insulating fluid (I/F) at various shear rates. The viscosities were measured on a Chandler 35 viscometer. Shear rate (s.sup.?1) Viscosity (cP) I/F V I/F VW I/F Si I/F SiW I/F LAW 1.1 7125 2672 6235 22712 2.3 3117 4231 1781 3563 16143 3.8 2138 2939 1336 2672 12692 7.5 1336 2138 935 1937 9152 11.3 1158 1737 802 1603 7704 22.6 802 1247 646 1225 5734 37.7 601 1109 534 1069 4696 75.4 494 1015 448 762 3497 113.2 454 1002 419 926 226.3 423 779 401 853

[0068] I/F stands for Insulating Fluid; V stands for vegetable oil; VW stands for vegetable oil with wax; Si stands for silicone oil; SiW stands for silicone oil with wax; and LAW stands for linear alkane with wax.

TABLE-US-00002 TABLE 2 shows thermal conductivity of the insulating fluid (I/F). I/F I/F I/F I/F I/F I/F I/F Fluid V VW Si SiW LAW LAMS LAWMS Thermal 0.159 0.168 0.138 0.155 0.163 0.097 0.088 conductivity (W/mK)

[0069] I/F stands for Insulating Fluid; V stands for vegetable oil; VW stands for vegetable oil with wax; Si stands for silicone oil; SiW stands for silicone oil with wax; LAW stands for linear alkane with wax; LAMS stands for linear alkane with microspheres; and LAWMS stands for linear alkane with wax and microspheres.

[0070] FIG. 2 shows the pipe 10, container 14 and connector 20. The method of insulating the pipe 10 includes installing the container 20 around the pipe 10 and adding the insulating fluid (not shown) to the space (not shown) between the pipe 10 and the container 20.

[0071] The system or series of containers 14 and connectors 20 is referred to as an assembly 30.

[0072] FIG. 3 shows the connector 20 for attaching together two containers (not shown). The connector 20 has two shoulders 22a & 22b that fit around the pipe (not shown). Each shoulder 22a & 22b receives an end of a container 14.

[0073] The shoulders 22a & 22b have holes 26a & 26b for bolts (not shown) that are passed through the holes 26a & 26b and into threaded holes (not shown) in the ends of the containers 14, to secure each end of a container to a connector 20.

[0074] The connector 20 has a port 24. The insulating fluid (not shown) is pumped into the annular space (not shown) via port 24 or a similar port (not shown) on the opposite side of the connector. The connector 20 also has ports 27a & 27b that allow insulating fluid (not shown) to flow out of the connector 20 and into the annular space (not shown) between the pipe and the container.

[0075] Some of the connectors 20 do not have the ports 27a & 27b and thereby allow sections of the system or series of containers and connectors (see FIG. 2) to be isolated or terminated.

[0076] FIG. 4 shows a container 14. The container 14 has lugs 28 that fit into sockets (not shown) in a connector 20. The threaded holes (not shown) in the end of the container 14, used to secure each end of a container to a connector 20, are in the lugs 28.

[0077] FIG. 5 shows the pipe 10, container 14, insulating fluid 12 and connector 20.

[0078] Generally, once the assembly 30 has been made-up, the insulating fluid 12 is pumped into the annular space (not shown) via a port (not shown) at the base of the assembly, filling the assembly until the fluid exits from the port 24 at the top of the assembly, indicating that the assembly is filled. The ports are then sealed and the pipe 10 has been insulated. The degree of insulation achieved will be directly related to the width of the annular space and therefore width and/or volume of insulating fluid. Because it uses prefabricated assembled components and the insulation, that is the insulating fluid, is pumped into place, the insulation can be installed quickly and efficiently and with reduced environmental risk.

[0079] Modifications and improvements can be incorporated herein without departing from the scope of the invention.