Experimental and mechanism study on wax deposit dissolution characteristics by light crude oil

During the sequential transportation of waxy crude oil and light oil, the previous formed wax deposits on the pipe wall will dissolve by light oil, which brings risks to the flow safety of the pipeline. This paper adopted a Couette wax deposit dissolution experimental device to systematically study the effects of dissolution duration, oil temperature, rotation speed and wax deposit properties on the dissolution characteristics of wax deposits. It is found that the dissolution of wax deposits is a process that starts quickly and then slows down. Moreover, the wax content of wax deposit also decreased during the dissolution process. The wax deposit dissolution process is mainly divided into five stages such as diffusion of wax molecules from wax deposit to the light oil and from bottom layer deposit to the wax deposit-oil interface, dissolution of wax crystal particles, weakening of wax deposit structural strength, and shear stripping of wax deposits. Finally, an empirical model of wax deposit dissolution was established and the undetermined parameters were fitted based on experimental data. The prediction results have good prediction accuracy with the experimental values.