A novel apparatus for producing sweet synthetic crude from a heavy hydrocarbon feed includes: an upgrader for receiving the heavy hydrocarbon feed and producing a distillate fraction including sour products, and high-carbon content by-products; a gasifier for receiving the high-carbon content by-products and producing synthetic fuel gas and sour by-products; a hydroprocessing unit for receiving the sour by-products and hydrogen gas, thereby producing gas and sweet crude; and a hydrogen recovery unit for receiving the synthetic fuel gas and producing further hydrogen gas and hydrogen-depleted synthetic fuel gas, the further hydrogen gas being supplied to the hydroprocessing unit.