About Calsep

Calsep stands for CALculation of SEParation processes. Calsep is a specialist company within oil and gas properties and phase equilibria. Consulting services, PVT and flow assurance software are the main products.

35 years of PVT services

From the first beta version and client to being a benchmark software and consultancy company.

At Calsep we are continuesly improving our software adapting to new technologies, consumer behaviour and tendencies in the oil and gas industry. From a humble start in Copenhagen in 1982 to offices in 4 continents offering services to the leading companies in the oil, gas and polymer industry.



Calsep A/S
Headquarter & Europe


Calsep FZ LLC
Middle East


Calsep, Inc.

Kuala Lumpur

Calsep Asia Pacific Sdn Bhd
Asia and Pacific

Global team

At Calsep we reach all continents, of course via online meetings but also via our staff and representation in United States, Europe, Asia and in the Middle East. For us it is a big value to be present where our clients typically operate.

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Latest News


Calsep will have a booth at ADIPEC 2023 in Abu Dhabi 2-5 October 2023. Join us at booth #430 and discover the latest developments in PVTsim Nova. Find out more about ADIPEC here: https://www.adipec.com

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Open book policy

It is Calsep policy to publish our research results on improved techniques for fluid description and modeling of phase equilibria. The research and development work has been documented in more than 60 publications and 2 textbooks, all authored or coauthored by Calsep’s consultants.

The publications cover subjects like:

  • EOS modeling
  • Solids precipitation and deposition
  • Computer algorithms for solving phase equilibria