Time is money, and for the O&G industry it’s no different. Quicker turnarounds can make well interventions less costly and even improve operations, safety, and profitability. Multiple runs to define operation envelopes and risk-based approaches for flow assurance require computational efficiency to meet engineering timeframes. ALFAsim’s latest release comes with major improvements in performance and user experience so you’ll never want to use other tools again.

The just-released ALFAsim version 1.8.0 brings new features, such as advanced case initialization, new IPR models to represent the reservoir, and more options for  boundary conditions. This release also allows you  to create cross plots between simulated variables so you can better assess case behavior.

Inside the major highlights for version 1.8.0

Advanced initialization

You can now initialize the simulation using interpolations along the pipes. The Constant option was replaced by a new option Table, which allows you to define different values throughout the edges for the main variables: pressure, velocity, volume fraction, temperature and tracer mass fraction. Those values can be entered by the user or interpolated between two points using three different methods: X-Axis, Y-Axis, and Length.

IPR models

Models to represent the reservoir behavior are now defined as a new item in the project tree. Two types of models are available: the Linear model, which considers a linear curve for the Inflow Performance Relationship (IPR); and the Table model, which relates a pressure difference and flow rate to define the IPR.

Equipment changes

Reservoir Inflow now uses an IPR model to define its productivity and injectivity indexes. Valve’s default type was changed from Perkins to Choke.

Boundary conditions improvements

Pressure nodes now have new options to prescribe the phase split in case of backflows. Five split types are available:

•  User-defined volume fractions: use constant volume fraction values for calculating the phase split
• User-defined mass fractions: use constant mass fraction values for calculating the phase split
• User-defined GOR and WC: use the gas-oil ratio (GOR) and water cut (WC) to calculate the phase split
• User-defined GLR and WC: use the gas-liquid ratio (GLR) and water cut (WC) to calculate the phase split
• Calculated from PVT model: calculate the local split by using the equilibrium conditions from the configured PVT model

Changes in the physics configuration

Also available: a new selection box to explicitly define the number of phases available. With that, only the related options will appear, depending on the number of phases selected. The Emulsion model was moved to the Advanced tab, and it is only available when Three Phase Flow is enabled. 

Changes in time options:

Maximum CFL value was moved to Numerical Options,

Maximum Timestep Change Factor was moved to Numerical Options,

Advanced tab was removed.

Changes in the numerical options:

• New Advanced tab containing Maximum CFL value and Maximum Timestep Change Factor
• New (Quasi-Newton based) nonlinear solver that may speed solution up to 2x
• New option Always repeat timestep (disabled by default) that increases solution speed up to 3x when not selected
• Replaced option Line-Search Type by Nonlinear Solver Type
• New button: Apply ALFAsim Recommended Configuration, which sets the numerical options to a configuration that favors performance
• New cache-related buttons: Enable solver caching, caching relative tolerance and caching absolute tolerance. These options are used to avoid recalculation of the friction factor and flow pattern, and may improve performance up to 1.5x

Improvements in post-processing

Addition of the ability to change the domain property in Trend and Profile plots. Dot clouds are displayed instead of curves when a non-default domain is used (default domain is Length for profiles and Time for trends).

Performance improvements:

• Improvement in thread parallelization by reducing thread imbalance, which resulted in a speed-up up to approximately 1.1x
• When using options set by the Apply ALFAsim Recommended Configuration button, simulations can be up to 6x faster

Text based input improvements

It is now possible to export and import .alfacase files, a text-based project file.

Fixes:

• Fixed the import of environment temperature profiles that were being incorrectly imported in some particular GENKEY files
• ALFAsim now calculates water cut and gas liquid ratio properties when not directly available in the PVT table
• Fixed the water properties calculation model when pressure and temperature values are outside correlations ranges

Known limitations

These are the known limitations for this version:

Project backwards compatibility: Only ALFAsim projects from 1.5.0 and later releases are supported

Tracers will not be considered when using Gas Lift Valves

When using Restart as the Initial Conditions Strategy and checking the Keep Previous Results option:

• The statistics displayed in the Plot windows are not updated to the restarted simulation and should be disregarded, and
• Trends that are generated from profiles after the simulation is run will be erased and show only the results from the restart point ahead

If annulus flow simulation is enabled, the user needs to check Use Nonsplit Equipment on the Numerical Options advanced tab in order to use Valves and Pumps.

When using the Compositional PVT Model:

• Single-component simulations are not supported yet
• All fluids with heavy components must have the same minimum number of single carbons
• When adding heavy components to the fluid composition, the number of single carbons must be sequentially ordered
• The compositional model currently does not work with the Steady State solver

ALFAsim case file limitations:

•  Nodes, wells, pipes and equipment must have unique names in the .alfacase file
• Discretization parameters are not supported in .alfacase files; only already discretized profiles can be imported

Download

For ALFAsim users:

1. Access the ESSS support center

2. Enter Username (your e-mail) and Password

3. If this is your first time accessing the portal, select Forgot my password

4. Download the installer for ALFAsim version 1.8.0

Support

Should you experience any difficulties while downloading or using this version, please do not hesitate to contact us. As always, your feedback and suggestions are greatly encouraged and appreciated. Our technical support team may be reached at support.esss.co.