GB1350866A - Method for bending and laying pipe under water - Google Patents

Abstract

1350866 Laying underwater pipe-line TRANSWORLD DRILLING CO 6 March 1972 10355/72 Heading F2P In a method for bending and laying a pipeline underwater to interconnect at least two installations 12, 28 at least one of which is offshore, pipe pulling means 24 is strung between the installations through pipe bending and straightening means 46, 48. Power means 42 pulls the pulling means 24 and pipe-line 44, attached to an end thereof, through the bending and straightening means 46, 48 from one installation 28 to the other 12, the ends of the pipeline then being connected thereto. As shown, each installation 12, 28 includes a platform 14, 30. In a first embodiment of the method a vessel 10 is positioned over the first installation having a wellhead 12 above the-mud line and workmen are lowered on a cable 11 in an open-bottomed chamber 15 which mates with the platform 14 and is then pumped-out. A buoy 16 is released through an opening 18 and trails a messenger line 20 which is then connected to a pulling cable 24 and is hauled down into the chamber 15 through the opening 18 in the platform. The chamber 15 is raised to the surface drawing the cable 24 through the opening 18 and the end is attached to a pulling vessel (27) (Fig. 3, not shown). The surface vessel 10 and chamber 15 are then positioned above the second wellhead 28 and the chamber is lowered to mate with the platform 30. A buoy (32) (Fig. 4, not shown) carrying a messenger line 20 is ejected through an opening 34 in the chamber 15 and connected at the surface to a cable 24 which is then hauled down into the chamber. The end 35 of the cable is attached to a buoy 36 and ejected through an opening 40 in the platform 30. The two pulling cables 24 are then connected at the surface and the pulling vessel 27, Fig. 6, hauls the cable 24 and pipe-line 44, which has been attached to the cable 24, through bending and straightneing rollers 46, 48 on the chamber 15 and platform 30. The pipe-line 44 may be either continuous or comprises lengths welded together as laying progresses. When the pipe 44 reaches the first platform 14 the pipe is severed at the second platform 30 and each end is subsequently connected to the wellheads 12, 28. The variations of the method of stringing the pulling cable 24 at the second installation 28, two lengths of cable are hauled down to and connected within the chamber 15 (Figs. 7, 8, not shown). Alternatively, the chamber 15 is raised to pull the cable through the platform opening 40 (Figs. 9, 10, not shown), or the chamber carries the cable down to the platform 30 as it is initially lowered. In other arrangements one of the installations is on hand (54) (Figs. 13, 14, not shown).