Experimental study on the wax deposit properties in the radial direction in crude oil pipeline: wax precipitation, carbon number distribution

The wax deposition experiments under cold and hot flow conditions were conducted in a flow loop apparatus using waxy crude oil. The wax precipitation characteristics and wax molecule carbon number distributions of wax deposit in the radial were investigated emphatically. The wax content and wax appearance temperature (WAT) of the surface deposits were lower than those at bottom. The mass ratio of wax molecules heavier than the critical carbon number (CCN) from high to low was the bottom deposit, surface deposit and crude oil, while in the range lighter than the CCN, the order was opposite. The CCN was C30 and the peak carbon numbers were C35 and C37 for the cold and hot flow experiments, respectively. This work deepens the understanding of the radial distribution characteristics of wax deposit and its intrinsic mechanism, affording a useful reference for the formulation of pigging plan.