| 摘要 |
A well system can include a drill string having a drill bit at an end thereof, and a swellable seal exposed to fluid in an annulus external to the drill string. The swellable seal can include a swellable material which swells in response to the fluid comprising a predetermined activating agent. A method of preventing undesired release of fluid from a wellbore can include displacing a drill string through the wellbore, thereby drilling the wellbore, and installing in the wellbore a swellable seal which, in response to the fluid comprising a predetermined activating agent, reduces flow through an annulus formed radially between the drill string and the wellbore. Another well system can include a swellable seal carried into a wellbore on a drill string, with the swellable seal including a swellable material which swells in response to a fluid in the wellbore comprising a predetermined activating agent. |
