Computational Fluid Dynamics
Hydrocarbon production systems are one of the most exposed industries to erosion degradation, but are not the unique sector that should involve mitigation measures in their design methods. The aim of the SDEA engineering team is to try and bring support to their clients by means of getting a deep understanding of the physics that control the process, using numerical modelling to provide very valuable information that can guide design decisions.
There are different potential mechanisms that could cause erosion damage like: sand erosion, liquid droplet erosion, cavitation bubbles or even involving some sort of chemical reaction leading to corrosion like HISC (Hydrogen Induced Stress Cracking).
In the case of erosion by particulates, the sand erosion has been object of study and testing from many different groups. These studies are well reflected in standards and disseminated to the engineering community, branching out the knowledge. Big oil and gas companies like BP, Exxon generate their own models and leading engineering organizations like API and DNV spread methods to mitigate erosion damage. Suggested models go from basic equations that limit the velocity of the fluid to more complex ones that involve particle velocity and impact damage functions to obtain the erosion rate.
The industry is moving towards more demanding requirements and DNV RP 0501 is one of the most comprehensive guidelines available. SDEA has extensive experience facing erosion problems using CFD tools. Our team has performed erosion predictions giving support to many of the major O&G companies, benchmarking our testing based on real data to asses our methods.
A sand erosion CFD model involves a two stage coupling calculation: in the first step, the flow equations are solved for operational conditions. Then, a DPM (discrete phase model) is used to calculate the sand particles trajectories using explicit algorithms. Finally, the erosion rates are calculated based on particles collision frequency onto the wet walls of the assembly.