Question

If a trap has a displacement pressure of 500 psi and the hydrocarbon column density difference is 0.2 g/cc, what is the maximum vertical column height the seal can support before capillary leakage occurs?

Accepted Answer

To calculate the maximum vertical column height a trap can support, use the formula H = Pd / (g * Δρ), where Pd is the displacement pressure, g is the acceleration due to gravity, and Δρ is the density difference between the brine and the hydrocarbon. Displacement pressure, measured here as 500 psi, is the pressure required for a non-wetting fluid like oil or gas to enter the pores of a rock seal. The density difference, 0.2 g/cc, represents the buoyancy force generated by the hydrocarbon column. First, convert units to a consistent system. Convert 500 psi to 3,447,379 Pascals (newtons per square meter). Convert the density difference of 0.2 g/cc to 200 kilograms per cubic meter. Use the standard gravitational constant of 9.81 meters per second squared for g. Plugging these values into the equation, H = 3,447,379 / (9.81 * 200) results in a height of approximately 1,757 meters. This height is the maximum vertical distance a hydrocarbon column can reach before the pressure at the base of the column exceeds the seal&#x27;s displacement pressure, causing the hydrocarbon to leak through the pore throats of the caprock.

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If a trap has a displacement pressure of 500 psi and the hydrocarbon column density difference is 0.2 g/cc, what is the maximum vertical column height the seal can support before capillary leakage occurs?