Typical shut-in pressure profile. A wellbore-pressure profile was acquired during a 72-hour shut-in period. The pressure spikes occurred when technicians increased the simulated hydrostatic pressure to account for fluid leaking off into the core. The rate of fluid leakoff is derived from the slope of the leakoff curve (inset).
стр. 8

Заранее спасибо

Буквально: Флюид начинает проникать в керн (но непонятно, что здесь имеется в виду под "керном")