| 摘要 |
<p>A plug for use in a wellbore, said plug (201; 301) having a body with an upstream end and a downstream end, characterised in that a major portion of the length of said body is hollow and open to the upstream end of said plug. A plug set for use in a wellbore, said plug set comprising a top plug and a bottom plug, characterised in that a major portion of the volume of said bottom plug is hollow and a major portion of the length of said top plug can be accommodated therein. A plug for use in a wellbore, said plug comprising a body and at least a first fin which is made of resilient material and which projects radially outwardly from said body to engage, in use, the inner wall of a tubular, characterised in that said first fin is segmented and is provided with means to inhibit liquid passing through the gaps between said segment. The body and fin(s) of the plug can be made as a one piece injection moulding. Alternatively, the plug may be of modular construction, each module comprising a body part and a fin and each module being separately injection moulded.</p> |
