Erosion CFD Analysis for Asset Life Extension

PDL Engineering Group are the experts in utilising advanced engineering software to solve complex technical problems for valve and actuator clients.

Recently the team worked closely with a global subsea technology and solutions provider to deliver specialist engineering analysis to determine the suitability of life extension for a group of subsea Christmas Trees (XTs), which were first commissioned in the 1990s with the expectation for them to continue in service until 2030.

PDL analysts used Computational Fluid Dynamics (CFD) to understand the potential erosion of the internal walls and calculate the material thickness lost over time caused by sand particle collisions, which were contained within the production fluid and walls.

The team used the mixture multiphase model to simulate the flow of gas, oil and water for each case with Eulerian-Lagriangian particle tracking employed for a range of sand particle size distributions, and the sand-wall collisions were quantified using an adapted version of the Tulsa erosion model. Sensitivities were performed to consider transients, particle size, erosion coefficients and sand mass flow rate, and the approach was validated with outputs from the industry standard erosion calculation tool, the client’s empirical data, and historical and forecast flow rate data.

The CFD analysis was used in conjunction with a Design of Experiments (DoE) to generate a response surface. This allowed for the interpolation of erosion rate over the entire historical and forecast production log flow conditions, enabling the calculation of representative material wall losses. This enabled PDL to account for every month of production in a fraction of the time and costs that it would otherwise take to solve each simulation individually.

CFD analysis to understand erosion at the choke

The assessment used to calculate the flow profile and particle tracks, with the outputs determining the cumulative wall losses was then used as a set of inputs for the subsequent Fatigue and Hydrogen Induced Stress Cracking (HISC) assessments.

The analyses helped the client understand the critical erosion regions and corresponding worst-case conditions and ultimately determined the suitability of life extension of the Christmas Trees from an erosion point of view.

To find out more about PDL’s proven track record with clients who rely on them to understand, validate and optimise their valves and actuators visit the PDL website https://pdl-group.com or connect on LinkedIn https://www.linkedin.com/company/pdl-solutions-europe-ltd

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