Consulting Service:

Customized PVT Software

Calsep offers customized PVT software solutions. It can be stand-alone solutions or solutions for integration in client or third party software.

Examples of software solutions delivered in the past are:

  • Dewpoint control of natural gas
  • Online dosage of hydrate inhibitor
  • Monitoring of H2S level in process plant
  • Thermodynamic engine for process and flow simulators
  • Conversion of multi-phase meter readings to production flow rates

Many of the customized software solutions Calsep has delivered are based on the PVTsim Open Structure modules:

  • Flash (PT, PH, PS UV, HS)
  • Hydrate flash
  • Wax PT flash

A Calsep customized software solution is delivered with an interface decided in a dialogue with the client. It can for example be delivered as a .dll or as an Excel sheet drawing on Calsep algorithms.


Compositional flow, process and reservoir simulators rely on a thermodynamic engine for performing EoS and property calculations. The engine must be numerically robust, execute fast and handle gas, oil, and aqueous phases. Derivatives expressing how phase amounts, phase compositions, etc. change with temperature and pressure are often needed for this type of simulators. Calsep can deliver a thermodynamic engine fulfilling all these requirements. A numerically and extremely fast flash code is combined with well tested models for physical properties (density, H, S, Cp) and transport properties (viscosity, thermal conductivity and surface tension).


Flow meters will provide gas, oil and water flow rates at meter conditions. For fiscal and allocation purposes flow rates are required at standard or other reference conditions. The conversion ratios are dependent on the separation process. The separation process can be a straight train of separators, or a non-standard one as exemplified in the below figure.

Example non-standard separation process for conversion of meter flow rates to flow rates at standard conditions.


The amount of water produced with a reservoir fluid may vary with time. If the well stream is transported in a subsea pipeline, the amount of inhibitor to prevent hydrate formation will also vary with time. If the transported amount of water can be measured prior to inlet to the pipeline, it is possible using a tailored Calsep software tool to continuously dose the right amount of inhibitor.


Hydrate formation may start when the temperature of a subsea pipeline reaches the hydrate formation temperature. Hydrate formation is associated with a significant heat release and the temperature of the transported fluid will not fall as much as would be the case if the aqueous phase remained in liquid form. The amount of hydrates formed can therefore be significantly less than simulated if the heat of formation was neglected. Calsep can deliver a hydrate PH flash algorithm that combined with a compositional flow simulator will provide a correct picture of the amount of hydrates formed in a pipeline exposed to cooling from ambient sea water.


The GOR ratio of the fluid produced from a petroleum reservoir may change with time. This may be the result of pressure depletion, or the GOR could be influenced by gas injected for EOR purposes. Calsep has delivered software solutions that takes the reservoir processes into account and modifies the original reservoir fluid composition to match the observed GOR variation with time.

Calsep Consulting Services:

Field Wide EoS Modeling


& Wax

PVT Software

A Calsep

Examples of
Recent Projects


Sørensen H., Sømme B.F., Use of Online PVT-package on Sigyn Vest for Converting Meter Flowrates to Export Conditions, 12th Interna- tional Conference on Multiphase Technology Barcelona, Spain, May 25th-27th, 2005

Lindeloff, N., Krejbjerg, K., Conversion of Multiphase Meter Flowrates, Multiphase ’01, June 13-15, 2001, Cannes, France

Rydahl, A.K., Sørensen, H., Coupling PVT Soft- ware with Multiphase Meters, 1st North American Conference on Multiphase Technol- ogy, Banff, Canada, June, 2000


Adil Pottayil

Regional Manager APAC and Senior Consultant
Calsep Asia Pacific SDN BHD

Caleb Watson

Calsep Inc. Houston

Henrik Sørensen

R&D Manager & Senior Principal Consultant
Calsep Copenhagen

Jawad Azeem Shaikh

Sales Director & Principal Consultant
Calsep FZ LLC. Dubai

Kristian Krejbjerg

President, Calsep Inc. & Principal Consultant
Calsep Houston

Lay Tiong Lim

Senior Consultant & Technical Sales
Calsep Asia Pacific SDN BHD

Lucas Farias Falcchi Corrêa

Calsep Copenhagen

Peter Jørgensen Herslund

Senior Consultant
Calsep Copenhagen

Peter Tybjerg

Manager & Principal Consultant
Calsep Copenhagen

Rasmus Risum Boesen

Senior Consultant
Calsep Copenhagen

Sukit Leekumjorn

Principal Consultant
Calsep Inc. Houston

Meet the rest of our team

At Calsep we reach all continents, either via online meetings or via our representatives in United States, Europe, Asia and the Middle East.