| 摘要 |
<p>A high pressure abrasive cutting medium 103 is used to cut through a string of underwater concentric casings 111 to 114 such that their upper parts, and any associated wellhead, can be removed. A low density medium such as air is delivered at high pressure into the inner casing 111 via pipe 122 thereby to displace seawater 123 from the cutting zone. To prevent the escape of compressed air, apertures in the underwater structure may be plugged e.g. by socks 161 filled with a settable material and inserted in their unset state into cement ports 151. Various other mechanical and chemical plugging devices are also disclosed (figures 5 to 16).</p> |
