High-Power Lasers to Remove Paraffin in Offshore Pipelines

Paraffin residue deposition in offshore pipelines is a long-standing operational issue occurring in several basins in Brazil and around the world due to the low temperatures and high pressures present on the seabed. This phenomenon can lead to an efficiency drop in fluid flow and an escalation in costs for the maintenance of subsea production equipment. The present research addresses the technical feasibility of a safer, more efficient, and lower-cost tool using the radiation of a high-power laser attached to a Remotely Operated Vehicle (ROV) to melt the paraffin, thereby removing the layers attached to the inner walls of the pipelines and enabling the proper flow to be restored. The high-power equipment used is a blue diode laser of maximum power of 1.8 kW, designed for industrial purposes requiring accurate and efficient interaction with materials. The laser beam is aimed at the exterior of the pipeline, heating it enough to reach the required temperature to melt the paraffin inside the pipe, conducting the heat without damaging the equipment that is submerged in the water. Numerical simulations and laboratory tests were carried out to optimize the parameters and achieve the best scenario, while ensuring the thermal efficiency of the process. In this work, a short pipe section to simulate an offshore pipe and industrial paraffin were used to carry out the laboratory experiments and multiphase simulations. Tests were carried out on a prototype submerged in water inside a tank to evaluate the thermal behavior of the paraffin in response to temperature variation. The temperature of the pipe section was monitored by Fiber Bragg Grating (FBG) temperature sensors. The melting point of paraffin is around 57ºC. The temperatures reached during the tests ranged from 60ºC to 84ºC, which was enough to melt the paraffin layers attached to the pipe, thus releasing them. This paper describes the results obtained in the laboratory and compares them with simulations, analyzing radiation time, distance, and power. The results of simulations and experiments with a high-power laser that can be used to melt paraffin in deep and ultra-deep water, where temperatures are very low, are analyzed. The laboratory tests provide controlled and reliable data for evaluating the performance of the tool, reducing the risk of damaging the equipment. The simulations provide the opportunity to investigate different scenarios and quickly visualize the results.