Study on the wax deposition of waxy crude in pipelines and its application

An experimental loop for the wax deposition study is established; a novel method to determine the thickness of the wax deposition in the experimental loop is developed, taking into account the impact of the instant temperature decreasing of the test section wall which leads to the increasing of the viscosity of the crude oil near the pipe wall and the distortion of the flow field in the pipe. The wax deposition characteristics of the QH crude are studied using the experimental loop. For the QH crude oil, there is a peak area of the wax deposition when it is 40 °C around. And very little deposition emerges when the temperature is not only higher than the wax appearance point but also lower than the temperature of solidification. It is also proved in the lab that the shearing dispersion of the wax crystal particles plays little role in the wax deposition when the shearing rate is high. The observation of the pipe which is cut in the field shows that the laying of the wax deposition in the pipe is very clear, and the wax deposition caused by the shearing dispersion exists clearly. From the angel of the shutdown temperature drop and safely restart for the hot oil pipeline, it is concluded that there is a permissible critical thickness of the sedimentary layer for the low flow rate pipelines.