Connate fluids

In geology and sedimentology, connate fluids are liquids that were trapped in the pores of sedimentary rocks as they were deposited. These liquids are largely composed of water, but also contain many mineral components as ions in solution.

As rocks are buried, they undergo lithification and the connate fluids are usually expelled. If the escape route for these fluids is blocked, the pore fluid pressure can build up, leading to overpressure.