What does the term 'percolate' refer to in the context of gas migration in a shut-in well?

In the context of gas migration in a shut-in well, the term 'percolate' refers specifically to the upward movement of gas. This phenomenon occurs when gas escapes from a reservoir and moves through the surrounding rock formations toward the surface. This can happen due to pressure differences, where gas travels through the pore spaces within the rock. The ability of gas to percolate is crucial in understanding how it behaves when a well is shut-in and helps in assessing potential hazards or changes in pressure that may affect the well’s integrity.

Understanding this term is critical in well control situations, as it relates to the safe management and monitoring of gas within wells. Recognizing the dynamics of gas migration can assist in implementing effective intervention strategies if undesired gas movement occurs.