The Industry Challenge:
Predicting flow behaviour is becoming more critical as Operators strive to control costs and ensure safe operations. The introduction of processes such as multi-stage hydraulic fracturing, downhole flow control devices and oilsands tailings management are increasing the scale and complexity of flow analysis.
Many of these new applications include multi-component, multi-phase liquids that might have shear rate and temperature dependencies that make it difficult to characterize the fluid behaviour.
Often heat losses and gains from various sources in the system can cause significant changes in the fluid properties, especially in cases where a phase change occurs such as steam flashing or condensing.
Events such as shutdowns and startups can also cause transient pressure and flow events that can damage equipment and set off alarms on monitoring systems.
Understanding the factors that influence the severity of these transients is required to design appropriate mitigation measures such as pipe restraints, flow control devices, process control algorithms and shutdown and startup procedures.
Conventional, analytical flow calculations cannot generally consider the level of detail, complexity and time-dependent behavior of these systems.
How We Help:
C-FER works with our clients to develop customized flow models using Computational Fluid Dynamics (CFD). These models describe the flow dynamics to help designers optimize the flow system and end users to operate the process safely and efficiently.
Customized models are developed of the flow path geometry and comprehensive fluid properties models are developed by combining standard fluid models with specific fluid properties from field or lab measurements.
Some applications require that the models also include discrete particles in the flow such as liquid droplets or solid particles to evaluate how these particles are transported through, or accumulate in, equipment.
This can include evaluating the effect of transient flow conditions in depositing particles from the flow or re-suspending settled particles. Tracking where the particles impinge on the equipment can also be used to identify where erosion is likely to occur.
This information aids in modifying the design to minimize high energy particle impact or incorporating erosion resistant materials in critical areas to extend the equipment life.
The analysis usually includes running a variety of simulations to investigate the flow characteristics over the full operating range. The analysis results can be plotted on the model geometry to help visualize the flow patterns and identify critical areas that could be improved by redesigning the flow path.
Fluid pressure and temperature distributions from the analysis can also be used as input to finite element models of the structural response of equipment to ensure safe operation in steady state and transient conditions.
C-FER uses the commercial CFD software CFX from ANSYS and also develops custom flow models to address specific industry needs.
The CFD approach has been used for the following applications:
- Thermal well completions;
- Downhole flow control devices;
- Oilsands tailings consolidation;
- Separator vessels; and
- Waste disposal in salt caverns.