Abstract: A high-pressure experimental apparatus for asphaltene precipitation is established and then used to determine the amount of asphaltene precipitation in degassed Caoqiao crude oil and recombined Caoqiao reservoir oil under gas (CO ₂ and hydrocarbon gas) injection.The scaling equation for normal pressure n -alkane/asphaltene system is extended to high-pressure gas-injected oil systems and then tested by comparison with the present experimental data and those available in the literature.The results show that it can give good predictions for asphaltene precipitation behavior in high-pressure gas-injected oil systems.