A two-dimensional mathematical dynamics model is presented to predict coke formation due to thermal cracking inside the tubes of fired heaters on two types of petroleum fluid. The laminar and turbulent flows are analyzed for both petroleum fluids. The second-order k-E standard model is adopted to make this mathematical model more accurate than previous models of coke formation. The radial and axial variations for temperature, velocity, and concentration due to the high temperature gradients inside the tubes are considered in the model equations. The finite volume method is the numerical model used to discretize the conservation equations. The proposed model is suitable to predict coke formation inside heater tubes since it indicates operational conditions where coke formation is minimized.