1. n. [Production Testing]

A phenomenon that occurs when gas enters the subsurface sucker-rod pump. After the downstroke begins, the compressed gas reaches the pressure needed to open the traveling valve before the traveling valve reaches liquid. The traveling valve opens slowly, without the drastic load change experienced in fluid pound. It does not cause premature equipment failure, but can indicate poor pump efficiency. A bottomhole separator or a gas anchor can correct gas interference.

See: bottomhole gas separator,  fluid pound,  gas anchor,  rod pump,  traveling valve