Unlike other [[Fractured membrane seal leakage|fractured seals]], hydrofractures remain open only as long as pore pressure exceeds fracture pressure. Once the total pressure drops, the fracture closes. The [[Hydrocarbon column|petroleum column]] height remains approximately in equilibrium with the difference between the water pressure and the fracture pressure. | Unlike other [[Fractured membrane seal leakage|fractured seals]], hydrofractures remain open only as long as pore pressure exceeds fracture pressure. Once the total pressure drops, the fracture closes. The [[Hydrocarbon column|petroleum column]] height remains approximately in equilibrium with the difference between the water pressure and the fracture pressure. |