Developed by PVT Specialists
PVTsim is developed by PVT specialists, but you do not need to be a specialist to make qualified use of PVTsim. Follow the recommended workflow and in a short time you will have the interface file you are after for a reservoir, flow or process simulator. PVTsim also offers PVT specialists the flexibility they require to lumping options, model selection and handling of complex phase equilibria, possibly including solid phases. Further down on this page we highlight key features in more detail.
PVTsim Nova Highlighted Features
Automated Input of PVT Data
PVTsim supports the PRODML 2.1 format by Energistics (energistics.org). PVT reports in PRODML 2.1 XML format are automatically imported into PVTsim. The data format covers:
- Bottom Hole Samples
- Separator Samples
- Oil Based Mud Compositions
- Classical Plus Fluid Compositions
- Extended Gas Chromatography to e.g. C36+
- Routine PVT and EOR Data
- Atmospheric Flash Test
- Saturation Point
- Separator Test
- Constant Mass Expansion
- Constant Volume Depletion
- Differential Depletion
- Swelling Test including CME and Viscosity Data
- Viscosity Data
Calsep’s Excel PVT Format is another option for automated input of PVT data. A PVT report in Calsep Excel PVT Format can be imported into PVTsim in one click. Four different templates are installed with PVTsim and support the above types of fluid compositions and PVT data. The templates support both metric, field and SI units
EoS Modeling Single Fluids
An equation of state (EoS) model for a reservoir fluid to be produced is a prerequisite for a qualified planning of the production and for an optimal design and operation of the production equipment.
PVTsim’s Auto EoS has more than 35 years of built-in experience. It enables users without specialist knowledge of PVT modeling to develop quality EoS models within minutes. The Auto EoS option performs a quality check of fluid compositions and PVT data and informs the user of possible inconsistencies. It suggests an appropriate lumping scheme and the weights to be assigned to the different types of PVT data to be matched, but allows the user to change the suggested settings.
Users with more experience in EoS modeling can use PVTsim’s options for Plus regression and Characterized regression. Plus regression is an assisted regression method that in a physically reasonable way changes how the EoS parameters of the C7+ components change with molecular weight. Characterized regression allows the user full freedom to change EoS parameters for all components as well as to tune on the binary interaction parameters.
Bottom hole samples will often be contaminated by drilling mud. In such cases, the mud will affect the PVT data measured for the fluid. PVTsim’s Clean for Mud module can not only perform a numerical cleaning of the fluid. It can also develop an EoS model for the clean reservoir fluid, taking into account the PVT data for the contaminated fluid.
PVTsim supports the SRK and PR (76 and 78 modifications) industry standard state equations of state, with and without volume correction. The volume correction can be made temperature dependent, which especially for heavy oils may be appropriate. Cubic equations may have difficulties predicting the isothermal compressibility of oils. Therefore, PVTsim offers the PC-SAFT equation as an alternative to the above-mentioned cubic equations. The PC-SAFT equation is developed primarily for polymer systems for which a correct prediction of compressibility is crucial.
Field Wide EoS Models
For fluids in communication and fluids produced through the same process plant, it is convenient to have a Common EoS model, which is a model that uses the same equation of state (EoS) parameters (Tc, Pc, acentric factor, etc.) for a number of different fluid compositions.
PVTsim’s Common EoS options support development of common EoS models with and without regression to PVT data. When developing a common EoS model with regression to PVT data, the user can assign individual weights to each type of PVT data for each fluid. If the data material covers gas injection swelling data, the option to tune to the critical point on the swelling curve is a powerful feature that will ensure a good representation of both gas condensates and oils to be represented by the same EoS model. One or more fluids can be mud contaminated and PVTsim will clean the fluids while regressing to the PVT data for the contaminated fluid.
New plus fluid compositions can be added to an existing EoS model.
PVTsim’s depth gradient option simulates the compositional variation with depth taking gravity segregation and a vertical temperature gradient into account. When multiple samples are available from different depths, it is possible to perform a regression that will estimate the key parameters of the thermal depth gradient term to provide a common EoS model that matches the compositional variation with depth.
Flow Assurance Features
PVTsim enables flow assurance engineers to check for precipitation of hydrates, wax, asphaltenes and scale and to determine the amount of composition of the precipitated material. The hydrate module makes it easy to conduct sensitivity studies in which amount of water, salinity and amount and composition of inhibitors are varied. Water analyses can be stored in the database and are readily available in the scale menu. The wax module supports tuning options to total wax content and wax formation temperature. The asphaltene module has a unique option for simulation of a complete asphaltene phase diagram and supports tuning to onset pressures for the reservoir fluid itself as well as for the reservoir fluid with gas added.
The polar nature of aqueous components calls for advanced models to accurately simulate the mutual solubility between aqueous and hydrocarbon phases. For mixtures with polar components PVTsim offers Huron-Vidal, CPA and Classical mixing rules along with both SRK and PR. Model parameters have been determined by Calsep based on an extensive amount of experimental data and are used for fluids with polar components.
Verification reports are available to PVTsim clients for the mutual solubility of gas-water, hydrates and scale.
PVTsim interfaces to some of the most widely used flow simulators including OLGA, LedaFlow and Pipesim.
Interfaces to Reservoir, Flow Assurance and Process Software
The interface modules provide easy export to the most widely used reservoir, flow assurance and process software. The interface files may contain EoS model parameters, physical properties or black oil data.
Plotting Tools & Import into PVTsim
Using the built in plotting tools it is easy to visually inspect the tables/black oil files for the reservoir simulators Eclipse, tNavigator, IMEX and Nexus and for the multiphase flow simulator OLGA.
The interfaces to Eclipse, tNavigator, OLGA Comptrack, and Prosper also offer an import functionality to import exported compositional EoS models.
Upgrades & Support
A PVTsim maintenance agreement with Calsep gives access to the latest version of PVTsim Nova and technical support from Calsep’s consultants who are specialized in thermodynamic modeling of all kinds of reservoir fluids. Calsep prioritizes a close contact with the clients and greatly appreciates their feedback. It enables Calsep to identify new needs for PVT simulation capabilities and this client input is used in the continued development of PVTsim.
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