Impermeable barrier

{
  "id": "MLC-T-OAG-001949",
  "term": "Impermeable barrier",
  "field": "Oil and gas",
  "definition": "A subsurface feature, such as a sealing fault, a pinch-out or a change to non-porous rock, that stops or sharply limits fluid flow across it. In a pressure transient test its effect appears once the disturbance reaches the barrier: the semilog slope doubles, and the log-log pressure derivative rises from its radial-flow plateau to a second plateau at twice the level. A single linear sealing fault is the usual case for this doubling.",
  "subject": "Well Testing",
  "url": "https://mlchart.com/terminology/oil-and-gas/impermeable-barrier/"
}