Process, method and system for removing heavy metals from fluids

Particulate mercury, in the form of metacinnabar, is removed from crude oil by thermally treating the crude oil at temperatures in a range from 150°C to 350°C and at a pressure sufficient to limit the amount of crude vaporizing to no more than 10 wt. %. In the thermal treatment, the particulate mercury is converted into elemental mercury, which can be removed by directly adsorption from the crude onto a support. In one embodiment, the elemental mercury can be removed by stripping the crude with a gas, and then adsorbing the mercury onto a support. The crude oil can be optionally treated prior to stabilization and contains 0.1 wt. % or more of C4-hydrocarbons. Following the thermal treatment, the treated crude is cooled and the pressure is reduced. The C4- hydrocarbons then vaporize from the crude and carry the elemental mercury with them. The elemental mercury in this hydrocarbon gas stream may then be removed by a solid adsorbent.