1. n. [Production Testing]
A condition in downhole pumping operations that occurs when the stroke length at the subsurface sucker-rod pump is longer than the surface stroke length (polished rod). This phenomenon is caused by the elongation of the rod string because of dynamic loads imposed by the pumping cycle. In this situation, when the upstroke begins at the surface, the downhole pump maybe still be moving downward; when the downstroke begins, the downhole pump is still moving upward.
See: sucker rod