Olga Simulator

The industry-standard tool for dynamic multiphase flow simulation

Overview

Over 30 years of research and development

Customer-supported innovation and research has been at the core of the Olga simulator’s development for more than 30 years. Validation of the Olga code with large-scale lab research and the largest database of actual production data from leading E&P companies are key factors in its ongoing development.

Major oil and engineering companies participate in the Olga Verification and Improvement Project (OVIP), which has collected the world’s largest database of lab and field data. This data has been used to validate and adapt the multiphase flow models. Results are continuously implemented in the Olga simulator, improving the core technology to better match the realities of operations.

Additionally, the Horizon project is cosponsored by seven major oil companies, which addresses problems related to the cost-effective development and safe operation of long-distance gas-condensate transport and long-distance transport of oil well streams.

Announcement

Equinor awards SLB contract for Leak Detection System for Johan Sverdrup Phase-II development

Equinor has, through a technical qualification study, selected SLB for delivering a novel Leak Detection and Virtual Flow Metering solution for the multiphase production network in Johan Sverdrup Phase II. The solution is based on the Olga Online* technology.

Olga 2026 Features

Olga 2026.1 release announcement

Update of Symmetry library

The latest Symmetry™ fluid engine release brings major stability and accuracy improvements for Olga compositional tracking and Symmetry flashes. Key highlights include:

Masked floating-point exceptions and corrected phase identification for gas–aqueous systems.
Enhanced pressure-enthalpy (P-H)-flash handling with consistent schemes for pressure-temperature (P–T) and PH flashes, ensuring stable density derivatives.
Fixes for internal flashes in inert and simplified three-phase cases when fluids are pure water or aqueous compounds.
Improved vapor-liquid equilibrium (VLE) predictions for CO₂–natural gas mixtures and better P-H-flash solutions for low-boiling-point fluids.

Update of Multiflash library

The KBC Multiflash library has been upgraded from 7.5 to 7.6, delivering improved accuracy and robustness for compositional tracking simulations. Highlights include:

Enhanced advanced cubic EOS model with updated binary interaction parameters (BIPs) and component properties for better accuracy.
More robust extrapolation near the critical point for continuous property predictions (notably heat capacity and enthalpy).
Faster model initialization and updated EOS-CG (Combustion Gas) to the latest 2021 publication.
Improved handling outside validity ranges with a fallback cubic EOS method, while high-accuracy aqueous EOS remains active for tracking..

Update of PVTSim library

The latest PVTSim Nova 7.2 release introduces key enhancements for Olga simulator integration:

Compositional tracking with PH Flash is now supported.
New option in the Olga tab file interface lets users control liquid–liquid splits. When two non-aqueous liquid phases occur (e.g. two hydrocarbons or a hydrocarbon and CO₂-rich phase), you can choose to merge them into one liquid or treat the lighter phase as gas in the tab file.
Ability to generate Olga PH tab files in both PVTSim Nova and PVTSim Nova CCS.

Directional leak functionality

The new directional leak feature improves depressurization simulations for stratified flow regimes, where gas sits above liquid in the pipeline. Unlike the default model (which assumes a well-mixed fluid), this functionality calculates leaked gas and liquid fractions based on:

Leak angle (position around the pipe circumference)
Leak diameter
Liquid level

Equilibrium fluid model for pumps and compressors

Olga simulator now supports a new FLUIDMODEL key for centrifugal pumps and compressors, with two options:

IDEAL (default in Olga 2025.2 and earlier): assumes ideal gas and incompressible liquid.
EQUILIBRIUM: uses the specified equation of state for more accurate calculations of pump head/torque and compressor compression ratio, without idealized assumptions.

CO₂ flow model

A dedicated CO₂ flow model is now available when the solver option is set to Olga new solver (CCS) and the flow model is set to Olga. It is designed for CO₂-dominated gas–liquid two-phase flow and ensures accurate simulation for these conditions. Compared to the Olga friction factor model, the pressure drop error is reduced by 51%, the hold-up error is decreased by approximately 31%, and the accuracy of flow regime prediction is increased by 34%.

See additional Olga 2026.1 features

Flow assurance and production webinar series

The webinar series targets users of the Olga dynamic multiphase flow simulator and the Pipesim steady-state multiphase flow simulator and associated consumers of the simulation results with the intent to share knowledge of the capabilities and best practice use of these powerful and versatile simulators.

Learn more