1. n. [Formation Evaluation]
A plug, or sample, taken from a conventional core for analysis. Core plugs are typically 1 in. to 1 1/2 in. [2.5 to 3.8 cm] in diameter and 1 in. to 2 in. [5 cm] long. Core plugs are ordinarily cut perpendicular to the axis of the core or parallel to the axis, called horizontal and vertical plugs, respectively, when cut from a vertical wellbore. The terms horizontal and vertical are often applied for cores cut from a deviated or horizontal wellbore, even though they are not strictly correct unless core orientation is measured and plugs are cut to the true in-situ orientation.