Flow Assurance

A flow assurance engineer needs a reliable simulation tool to tell whether there is a risk of precipitation of gas hydrates, wax, asphaltenes or scale.

PVTsim’s Flow Assurance package provides the answers to these questions and will, if so, quantify the amounts of precipitated solids and determine the correct dosage of hydrate inhibitor needed to avoid hydrate formation. The wax and asphaltene models can be tuned to match experimental precipitation data. The water content in gas and oil phases in contact with a water phase is determined accurately using extensions of the classical cubic equations (Huron-Vidal and CPA). The compositional changes that may occur during the life time of a reservoir can be accounted for using the options for recombination and mixing. The package handles compressors, expanders, heaters, pumps, valves and 3-phase separators. The validity of the PVTsim models to simulate the mutual solubility of water and hydrocarbons, hydrates and scale is documented against experimental data in PVTsim’s verification reports. Fluid descriptions made in PVTsim can be exported to OLGA, LedaFlow, Pipephase and Pipesim.

Modules | Flow Assurance

BASE

The BASE module is the gateway to PVTsim’s diverse capabilities for simulating reservoir fluid phase behavior from reservoir to refinery. Compositional analyses and PVT data from a PVT report are easily entered into and stored in a PVTsim database.

Important features of the Base module include:

• Extensive pure component library
• Input of GC and TBP compositions
• Normal and heavy oil characterization
• CSP and LBC viscosity models
• Flexible component lumping and preset lumping schemes
• Recombination of separator oil & gas
• Mixing or weaving of up to 100 different fluids
• 2 phase flash and phase envelope simulations

PVTsim may be used with the industry standard SRK or PR equations (76 or 78 modifications) in their original form or volume corrected. The GERG-2008 ensures accurate results for natural gases. More complex heavy oil phase equilibria can be handled using PC-SAFT equation

PROPERTY GENERATOR

The property generator is a tool for generating fluid property tables in a pressure and temperature grid. The tables can be used to get an overview of how selected properties develop with pressure or temperature. The options for customizing output also make the module suited for fluid property input to software that does not have a dedicated interface available in PVTsim. The modules considers up to three phases (gas, oil and water).

FLASH & UNIT OPERATIONS

PVTsim’s numerous flash options have been developed in close collaboration with process engineers to cover all common needs for flash specifications. The options include PT, PH, PS, VT, UV, HS, K-factor, Split-factor, P-Beta and T-Beta calculations. For systems without aqueous components, the flash calculations will typically be limited to two phases (gas and oil). For systems with water, a polar model (Huron-Vidal or CPA), can be used to give an accurate representation of the water concentration in the gas and oil phases and the amount of dissolved gas in the water phase. A PT multiphase flash option (up to 5 phases) is available for complex simulations or to reveal an unphysical model description.

A hydrocarbon fluid can be saturated by water at a given pressure and temperature. The water phase envelope option gives a complete overview of the phase boundaries for a hydrocarbon system with water and possible hydrate inhibitors.

The Flash and Unit Operations module covers simulation capabilities for the most common unit operations including compressors, expanders, coolers, heaters, pumps and valves. A multi-stage 3-phase separator option enables simulation of the amount of produced water at standard conditions from a reservoir fluid saturated by water at reservoir conditions.

HYDRATE

PVTsim’s Hydrate module accurately simulates hydrate formation conditions of gas and oil mixtures carrying water. Depression of the hydrate formation temperature in the presence of salts and hydrate inhibitors (MeOH, EtOH, MEG, DEG, TEG) is simulated while accounting for the loss of inhibitor to the hydrocarbon phases. PVTsim automatically detects the stable hydrate structure (I, II or H) and the calculations are documented against experimental data in PVTsim’s hydrate verification reports.

The flash options (PT and PH) consider formation of hydrates (structures I, II and H) as well as gas, liquid and aqueous phases, solid salt phases, and ice. The minimum amount of a specified inhibitor to be added to prevent hydrate formation at a given pressure and temperature can be calculated with the Minimum Inhibitor option. The Hydrate PT curve option may be used to plot the hydrate curve in the relevant pressure range with or without inhibitor added.

WAX

The Wax module enables users to assess the wax potential of a reservoir The Wax module simulates the wax appearance temperature (WAT) of a reservoir fluid, the amount of wax formed at lower temperatures, and the total wax content in the fluid. The PT curve option gives an overview of how dissolved gas and pressure affect the wax formation conditions. The PT flash option considers gas, oil and wax phases. The wax simulations can be performed with a standard compositional analysis as input. If available, an n-paraffin analysis may be entered with the fluid.
If experimental wax data is available, it is possible to tune the wax model to an experimental WAT and/or to the experimental wax content in the stock tank oil. Non-Newtonian viscosity calculations considering the effect of precipitated wax are supported.

ASPHALTENE

With the PVTsim Asphaltene module it is possible to evaluate the conditions at which asphaltene precipitation takes place. The asphaltene phase envelope option provides a complete overview of the temperature and pressure regions with asphaltene precipitation. The effect of gas injection on the asphaltene precipitation conditions can be studied using the Px-curve simulation option. It is possible to tune to experimental asphaltene data while also matching bubble point pressure data. Cubic equations of state as well as the PC-SAFT equation are available for asphaltene simulations.

SCALE

The potential for scale (salt) precipitation from formation water and seawater mixtures can be analyzed using the Scale module. Water analyses are easily stored in the database and selected for simulation in the Scale menu.

The following salts are considered: BaSO4, CaSO4, SrSO4, CaCO3, FeS and FeCO3.

Pressure and temperature effects, CO2 and H2S equilibrium pressures in the water, pH as well as the effect of other ionic species (primarily NaCl, CaCl2 and KCl) are all taken into account. Pitzer’s activity coefficient model is used. 2D and 3D plot options make it straightforward to establish an overview of the scale formation conditions.

Interfaces | Flow Assurance

FLOW ASSURANCE INTERFACES

Flow Assurance Interfaces covers OLGA, LedaFlow, Pipesim, Pipephase, and Turbulent Flux.

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Modules Specification

MODULES

INTERFACES

Flow Assurance

A flow assurance engineer needs a reliable simulation tool to tell whether there is a risk of precipitation of gas hydrates, wax, asphaltenes or scale.

Modules | Flow Assurance

Interfaces | Flow Assurance

Compare each module

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