Provided are embodiments that include a hydrocarbon fluid processing system including an ultrasonic hydrocarbon degassing unit including a vapor recovery vessel adapted to direct flow of a hydrocarbon fluid mixture along a flowpath extending through an interior of the vapor recovery vessel, and an ultrasonic transducer system disposed inside the vapor recovery vessel and in the flowpath of the hydrocarbon fluid mixture. The hydrocarbon fluid mixture including a hydrocarbon liquid and a gas entrained in the hydrocarbon liquid, the ultrasonic transducer system adapted to transmit ultrasonic signals into the hydrocarbon fluid mixture along the flowpath, and the ultrasonic signals adapted to separate the gas from the hydrocarbon liquid.