Olga 2025.2 is available now
Tuesday, 17 June 2025
Product overview
The Olga™ dynamic multiphase flow simulator models transient flow (time-dependent behaviors) to maximize production potential. Transient modeling is an essential component for feasibility studies and field development design. Dynamic simulation is essential in deep water and is used extensively in both offshore and onshore developments, to investigate transient behavior in pipelines and wellbores. Transient simulation with the Olga simulator provides an added dimension to steady-state analysis by predicting system dynamics, such as time-varying changes in flow rates, fluid compositions, temperature, solids deposition, and operational changes. From wellbore dynamics, for any well completion to pipeline systems with various types of process equipment, the Olga simulator provides an accurate prediction of key operational conditions involving transient flow.
Release updates
As part of our ongoing commitment to excellence, we continuously strive to enhance our product. This latest version brings multiple improvements, updates, and bug-fixes to benefit our users. The most important improvements are mentioned in this document below. Please read the release notes for the full overview.
Plots saved to the case-configuration
Previously, the plotting configuration for a case was discarded whenever the case was closed. Now, this configuration is saved within the case file, allowing plots to be automatically reloaded when the case is reopened. This enhancement applies to all types of 2D plots.
The feature can be disabled via the Olga options panel. Additionally, several plot-specific settings—such as axis scales, series scales, and series configurations—are now preserved as part of the saved configuration.
You can also now assign custom names to plots, making it easier to distinguish between them. When duplicating a case, the plotting configuration is carried over as well. However, if the result files are deleted, the plotting configuration will also be removed the next time the case is opened.
Plot-series alignment in plots
It is now possible to initialize profile and trend plots with an offset applied to the x-axis—length for profile plots and time for trend plots.
For profile plots, the offset granularity is per branch, allowing different branches to be arranged sequentially. In trend plots, the offset is applied per file, enabling simulation results to be shifted in time.
Offset values are preserved when the case is saved, ensuring consistent plot alignment across sessions.
Compare external data with Olga Simulations
We’ve introduced powerful new functionality to the plotting tool that enables you to import and compare external data directly with OLGA simulation results. For trend plots, you can now paste in measurement data along with corresponding timestamps to visualize and compare it against simulation outputs. For profile plots, in addition to time and data values, you can also specify a position, allowing for the comparison of spatial profiles along pipelines or other position-based data.
External datasets can be saved in CSV format, reopened later, and further edited directly within the plotting tool. This enhancement significantly improves the ability to validate simulations against field data and offers greater flexibility in your analysis workflow.
PVT packages for calculation of inhibitor properties
The PVT package used for calculating inhibitor properties is specified using the INHIBITORPROPERTIES key under the OPTIONS section. In addition to the previously available options—Simple and Multiflash—two new PVT packages are now supported: Symmetry and PVTSim..
Lennard-Jones viscosity model enabled for Multiflash
The Lennard-Jones viscosity model in Multiflash is now enabled for Olga compositional tracking simulations.
Level gradient in steady-state pre-processor
Previously, the level gradient term was not included in the steady-state pre-processor. Now, it is incorporated into the force balance calculations for oil and water layers within the steady-state pre-processor. The level gradient term influences the holdup calculations, particularly where changes occur due to pipe inclinations or rate adjustments. This is especially relevant at moderate superficial gas velocities with a very low liquid-to-gas ratio in large pipes. Incorporating this term into the steady-state pre-processor enhances the accuracy of holdup predictions.
However, this improvement comes at the cost of increased processing time, as the convergence time for the steady-state pre-processor may rise. It is important to note that in dynamic simulations, a more accurate steady-state condition can ultimately reduce the total simulation time. To illustrate the concept, a simple Olga model was set up, as shown in Figure 1
Figure 1 - Olga model for demonstrating Level Gradient
An analysis of the hold-up trends using Olga version 2025.1.2 compared to Olga 2025.2, as depicted in Figure 2, reveals that the hold-up begins at 0.09 with a level gradient of zero for Olga 2025.1.2. As the simulation progresses, the hold-up value exhibits a declining gradient across the flowline. The simulation reaches a steady state after approximately 4.7 hours. The red line represents the hold-up value using Olga 2025.1.2.
Figure 2 - Hold-up trends Olga 2025.1.2 vs Olga 2025.2
Comparing these results with Olga 2025.2, represented by the black line, it can be observed that the steady state pre-processor calculates the steady state conditions, allowing the simulation to directly reach steady state. Although the steady state pre-processor might take longer to converge, the overall simulation time could be shorter than before.
