An expression which applies to a method developed for the purpose of logging highly [[deviated hole|deviated holes]] and holes with serious bridging problems. At the present time, systems such as this involve the use of [[drill pipe]] to carry specially designed well-logging tools through highly deviated boreholes or past wellbore constrictions to a depth where logging can be performed. A [[survey cable]] connects the downhole logging instrument to the surface where the measurements are recorded.

Usually, this is an operation designed for performing openhole surveys below a surface- or protective [[casing string]], but can be used for performing some cased-hole surveys as well. Examples are [[Slant hole Express|Slant-hole Express]] and [[Toolpusher]].

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