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.

Start in 1982

Calsep was founded in 1982 to offer simulation services to the oil and gas industry. The founder, Karen Schou Pedersen, had a background in physical chemistry and liquid physics and started the company with the ambition to see compositional simulation techniques for reservoir fluids gradually replace the black oil correlations which, at the time, were the preferred tool for PVT simulations in the oil and gas industry.

The first client

The Norwegian oil company Statoil was Calsep’s first client. New technical solutions and new software simulation techniques had to be invented in the early 1980s when oil and gas production in the North Sea had just started. Statoil decided to set new standards for PVT software and asked Calsep to develop a fully compositional PVT simulation package. Many of the PVT simulation techniques, which are industrial standards today, were developed in a fruitful collaboration with Statoil in Calsep’s early years.

PVTsim software package PVTsim

In 1988 Calsep released the 1^st version of the PVT simulator, PVTsim. It was a user-friendly PC program marketed at a time when mainframe computers were still in common use in the oil industry. PVT laboratories were the first to adopt the new program as a useful tool for planning and checking PVT measurements. Within the next couple of years PVTsim was further developed to satisfy almost every need for PVT simulation in the oil industry. PVTsim is today an industrial standard for PVT simulation.

EoS modeling services

Right from the start in 1982 Calsep has provided PVT simulations as a consulting service for the oil industry. Most studies are conducted with PVTsim and Calsep consultants have typically contributed to the development of the program, and therefore know PVTsim better than anyone else. New simulation procedures have been developed along the road. Examples are characterization of multiple well streams to a unique set of pseudo-components and simulation of compositional variation with depth under the influence of a vertical temperature gradient.

Moving into flow assurance

In the years around 1990 Calsep developed simulation techniques to predict formation of gas hydrates, wax, asphaltenes and scales (salt). Since then Calsep has performed several flow assurance studies for clients. Examples are studies evaluating the need for addition of hydrate inhibitors in sub-sea pipelines and studies on pigging frequency for pipelines with wax deposition.

PVTsim Nova

PVTsim has continuously been developed since the first release in 1988. In 2007 Calsep decided to create a new .NET based platform for PVTsim. The aim was to have a program that was even more user friendly than the old PVTsim with new features users had been asking for in the past. More than anything, Calsep wanted to create a new platform that could take PVTsim into the next decade and provide models and features never seen before in a PVT simulator. In May 2014 PVTsim Nova was released. Nova rollout events were organized worldwide. PVTsim Nova was well received. Much useful input for future development was received from those events.

New offices

Calsep head office is in Kgs. Lyngby, a suburb of Copenhagen. In 1999 Calsep opened an office in Houston, Texas, and in 2005 an office was opened in Dubai, UAE. In 2009 Calsep opened an office in Kuala Lumpur, Malaysia. Calsep is today able to offer consulting services around the globe.

Copenhagen

Calsep A/S
Headquarter & Europe

Dubai

Calsep FZ LLC
Middle East

Houston

Calsep, Inc.
US and LATAM

Kuala Lumpur

Calsep Asia Pacific Sdn Bhd
Asia and Pacific

PVTsim Nova 7.1 Released

We are pleased to announce that PVTsim Nova 7.1 has been released. Find the list of updates here: Software Updates | Calsep

PVTsim Nova 7.0 to 7.1

PVTSIM LEDAFLOW API EOS MODELS CPA Equation of State included. FLUID HANDLING UPDATED EDIT COMMON EOS GROUP MENU New Composition tab added showing compositions for…

PVTsim Nova User Group Meeting in Stavanger, April 9

We are happy to announce the 2025 PVTsim Nova User Group Meeting in Stavanger. This event will showcase the latest functionalities and enhancements in PVTsim…

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Publications

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

Publications

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

Copenhagen

Dubai

Houston

Kuala Lumpur

Latest Tech Talk, Software Updates & Releases

PVTsim Nova 7.1 Released

PVTsim Nova 7.0 to 7.1

PVTsim Nova User Group Meeting in Stavanger, April 9

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Publications