An apparatus for withdrawing fluid from an earth formation comprising an elongated housing, a first inflatable elastomeric seal adapted to expansively fill an annular space between the housing and the wall of a wellbore. The seal includes axially spaced seal lips protruding from a surface of the seal....http://www.google.de/patents/US5549159?utm_source=gb-gplus-sharePatent US5549159 - Formation testing method and apparatus using multiple radially-segmented fluid probes
