Principles and Advantages of High-Power Lasers for Descaling Surface Equipment

Abstract

This work examines the physical principles and effects of high-power laser (HPL) descaling of surface equipment. This contactless technique can fully remove sulfide or calcium carbonate scale without compromising the integrity of the substrate. The method is environmentally friendly, waterless, and energy efficient. It could do away with chemical and mechanical methods for descaling, which have shown low efficiency treating fully-plugged deposits and environmental risks due to chemical use. This paper describes the process through an analysis of its efficiency and impact on the substrate material, the environment, and the implications to production reliability. HPL descaling is described by a multiphysics approach that involves thermal and mechanical processes. The laser causes a phase-change on all or some of the constituents of the scale. This interaction results in spallation, dissociation, and at high energy sublimation. Laser-matter interaction is precise. It produces a small heat affected zone (HAZ) that decays exponentially away from the illuminated area. Thus, the effect of the laser on the surrounding material is minimal to none. Ultrasonic, multi-spectral imaging, microscopy, and statistical analysis are used to analyze the effect of the laser on the substrate material. The environmental impact of the HPL process is compared to existing methods; it is calculated via the carbon intensity of each step and supporting equipment involved in the processes, as well as by its impact to material reuse, waste reduction, and recycling. Scaling can be detrimental to oil and gas production because it may hinder the flow of fluids from and to the well. In surface systems, scale deposits reduce the internal diameter of equipment, thus limiting flow-rate capacity and causing pressure drops across the production network. From a physics perspective, the process is effective because the energy can be delivered with extreme precision on the target. The efficiency of the process depends on the coupling of the HPL with the target and the rate of debris evacuation. The physics are complex but can be optimized through machine learning (e.g. reinforcement learning). The results of the comprehensive characterization demonstrate that HPL descaling preserves the integrity of the substrate. HPL descaling could increase the lifetime of surface equipment affected by scale, and hence contribute to reuse and recycling. The adverse effects of scaling make prevention and removal crucial to the energy industry. Existing methods of scale-removal rely on mechanical or chemical scrubbing, which show varying degrees of success and may deteriorate the substrate. HPL descaling is an environmentally-friendly solution for production reliability; it enables complete descaling and the safe reuse or recycling of scaled equipment.