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


Agger, C., Sørensen, H.
Method Of Characteristics For Generating EOR Oil Recovery Curves
SPE-205918-MS, SPE Annual Technical Conference and Exhibition, Dubai, UAE, September 2021.

Vinhal, A., Azeem, J., Pedersen, K.S.,
Modeling of Compositional Grading in Heavy Oil Fields
SPE-205887-MS, SPE Annual Technical Conference and Exhibition, Dubai, UAE, September 2021.


Leekumjorn, S., Boesen, R.R., Sørensen, H., Krejbjerg, K.
Asphaltene Modeling with Cubic and More Complex Equations of State.
SPE-203491-MS, Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE, November 9-12, 2020.

Aoki, T., Furuta, T., Leekumjorn, S., Azeem, J.S., Pedersen, K.S., Alobeidli, A., Mogensen, K.
A New Technique for Common EoS Model Development for Multiple Reservoir Fluids with Gas injection.
SPE-202923-MS, Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE, November 9-12, 2020.

Sørensen, H., Boesen, R.R., Leekumjorn S. and Herslund, P.J.
Peng-Robinson Equation of State Extended to Handle Aqueous Components Using CPA Concept
Journal of Natural Gas Engineering, 3 (1), 2018, pp. 1-38. DOI: 10.7569/JNGE.2018.692501

Boesen, R.R., Sørensen, H. and Pedersen, K.S.
Asphaltene Predictions Using Screening Methods and Equations of State
SPE 190401-MS, SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman, 26-28 March 2018

Agger, C.S. and Sørensen, H.
Algorithm for Constructing Complete Asphaltene PT and Px Phase Diagrams.
Industrial & Engineering Chemistry Research, 57 (1), 2018, pp. 392-402. DOI: 10.1021/acs.iecr.7b04246

Tybjerg, P., Pedersen, K.S. and Krejbjerg, K.,
Reservoir Fluid Characterization Procedure for PC-SAFT Equation of State
SPE 187170-MS, SPE ATCE, San Antonio, Texas, 9-11 October 2017.

Sørensen, H., Shaikh J.A.
CO2 Gas Injection as an EOR Technique – Phase Behavior Considerations
Cutting-Edge Technology for Carbon Capture, Utilization and Storage, Clermont-Ferrand, France, 24 -27 September, 2017

Boesen, R. R., Herslund, P. J., and Sørensen, H.
Loss of Monoethylene Glycol to CO2-and H2S-Rich Fluids: Modeled Using Soave–Redlich–Kwong with the Huron and Vidal Mixing Rule and Cubic-Plus-Association Equations of State.
Energy & Fuels 31, 2017, pp. 3417–3426

Meisingset, K.K. and Pedersen, K.S.,
Joule-Thomson Coefficient from Well Test Analysis Data
SPE-181622-MS, SPE ATCE in Dubai, UAE, 26–28 September 2016.

Kumar, A., Gohary, M.E., Pedersen, K.S, and Azeem, J.,
Gas Injection as an Enhanced Recovery Technique for Gas Condensates. A comparison of three Injection Gases
SPE 177778-MS, Abu Dhabi International Petroleum Exhibition and Conference. UAE, 9-12 November, 2015.

Pedersen, K.S. and Hjermstad, H.P.
Modeling of Compositional Variation with Depth for Five North Sea Reservoirs
SPE 175085-MS, SPE ATCE Houston, Tx, September 28-30, 2015.

Bartolome, P., Tybjerg, P., Pottayil, A.,
Wax deposition in North Sea reservoir wells: field observations and simulations
17th International Conference on Multiphase Technology, Cannes, France: 10-12 June 2015

Hustad, O. S., Jia, N.J., Pedersen, K.S., Memon, A., Leekumjorn, S.
High Pressure Data and Modeling Results for Phase Behavior and Asphaltene Onsets of GoM Oil Mixed with Nitrogen
SPE Reservoir Eval. Eng. 3, 2014, pp. 384-395.

Pedersen, K.S., Christensen, P.L., Azeem, J.
Phase Behavior of Petroleum Reservoir Fluids, 2nd edition
Taylor & Francis, Boca Raton, US, 2014

Boesen, R.R., Sørensen, H. and Pedersen, K.S.
New Approach for Hydrate Flash Calculations
Proceedings of the 8th International Conference on Gas Hydrates (ICGH8-2014), Beijing, July 28th – August 1st, 2014

Lindeloff, N.L., Mogensen, K., Pedersen, K.S., Tybjerg, P., Noman, R.
Investigation of Miscibility Behavior of CO2 rich Hydrocarbon Systems – With Application for Gas Injection EOR
SPE 166270-MS, SPE Annual Technical Conference and Exhibition, New Orleans, LA, USA, 30 September–2 October 2013

Sørensen, H., Pedersen, K.S., Christensen, P.L.
Method for Generating Shale Gas Fluid Composition from Depleted Sample
Presented at Forth International Acid Gas Injection Symposium (AGIS IV), Calgary, September 24 – 27, 2013

Leekumjorn, S. and Krejbjerg, K
Phase Behavior of Reservoir Fluids: Comparisons of PC-SAFT and Cubic Equation of State Simulations
Fluid Phase Equilibria 359, 2013, pp. 17-23

Pedersen, K.S., Leekumjorn, S., Krejbjerg, K. and Azeem, J.
Modeling of EOR PVT data using PC-SAFT equation
SPE-162346-PP , Abu Dhabi International Petroleum Exhibition & Conference, Abu Dhabi, UAE, 11–14 November, 2012

Pedersen, K.S., Azeem, J. and Rasmussen, C.P.
1D asphaltene deposition simulator for reservoir fluids undergoing gas injection
SPE-155447-PP, SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman, 16–18 April 2012

Sah, P., Gurdial,G., Pedersen, K.S., Izwan,H., and Ramli, F.
Equation-Of-State Modeling For Reservoir Fluid Samples Contaminated By Oil-Based Drilling Mud Using Contaminated Fluid PVT Data
SPE Reservoir Evaluation & Engineering, 15, 2012, pp. 139-149

Larsen, J., Sørensen, H., Yang, T., Pedersen, K. S.
EOS and Viscosity Modeling for a highly undersaturated Gulf of Mexico Reservoir Fluid
SPE-147075-PP,SPE ATCE, 30 October – 2 November 2011, Denver, Co

Al-Ajmi, M. F., Tybjerg, P. , Rasmussen, C. P., Azeem, J.
EoS Modeling for Two Major Kuwaiti Oil Reservoirs
SPE 141241-PP, MEOS, Bahrain, 26–28 September, 2011

Sah, P., Pedersen, K. S., and Shaikh, J.A.
EOS modelling, the first step in detailed EOR potential evaluation – A case study
SPE-144025, EORC, Kuala Lumpur, Malaysia. July 19-21, 2011

Shaikh, J.A. and Sah, P.
Experimental PVT data needed to develop EOS model for EOR projects
SPE-144023, EORC, Kuala Lumpur, Malaysia. July 19-21, 2011

Hemmingsen, P.V., Burgass, R., Pedersen, K. S., Kinnari, K. and Sørensen, H.,
Hydrate temperature depression of MEG solutions at concentration up to 60 wt%. Experimental data and simulation results
Fluid Phase Equilibria 307, 2011, pp. 175-179


Negahban, S., Pedersen, K. S., Baisoni, M.A., Sah, P., and Azeem, J.
An EOS Model for a Middle East Reservoir Fluid with an Extensive EOR PVT Data Material
SPE-136530-PP, Abu Dhabi International Petroleum Exhibition & Conference in Abu Dhabi, UAE, November 1-4, 2010

Sonne, J., Pedersen, K.S.
Simulation of Hydrate Growth in Steady State Flow Lines
BHR 14th International Conference on Multiphase Production Technology, Cannes, France, June 17 – 19, 2009.

Hadsbjerg C. and Krejbjerg K.
Challenges in Hydrate Plug Prevention in Pipelines Seen Over the Lifetime of a Field
ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2009), 7, 2009, pp. 435-443

Pedersen, K.S. and Sørensen, C.H.
PC-SAFT Equation of State Applied to Petroleum Reservoir Fluids
SPE-110483-PP, SPE ATCE, Anaheim. November 11-14, 2007

Pedersen, K.S., Christensen, P.L.
Fluid in Hydrocarbon Basins
Chapter in Reviews in Mineralogy & Geochemistry, Vol 65, Mineralogical Society of America Geochemical Society, 2007.

Gibson, A., Sørensen, H., Abdou, M., Sener, I.
New Method for the Non-Equilibrium Initialisation of Reservoir Models with Lateral and Vertical Variation in the Initial Fluid Composition
SPE 101247, Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE, November 5-8, 2006

Pedersen, K.S., Hjermstad, H.P.
Modeling of Large Hydrocarbon Compositional Gradient
SPE 101275, Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE, November 5-8, 2006.

Rasmussen, C.P., Krejbjerg, K., Michelsen, M.L., Bjurstrøm, K.E.
Increasing Computational Speed of Flash Calculations with Applications for Compositional, Transient Simulations
SPE Reservoir Evaluation & Engineering, February 2006, pp. 32-38

Lundstrøm, C., Michelsen, M.L., Kontogeorgis, G.M., Pedersen, K.S. and Sørensen, H.
Comparison of SRK and CPA Equations of State for Physical Properties of Water and Methanol
Fluid Phase Equilibria 247, 2006, pp. 149-157

Pedersen, K.S., Christensen, P.L.
Phase Behavior of Petroleum Reservoir Fluids
Taylor & Francis, Boca Raton, US, 2006.

Krejbejrg, K., Pedersen, K.S..
Controlling VLLE Equilibrium with a Cubic EOS in Heavy Oil Modeling
Presented at the Petroleum Society’s 7th Canadian International Petroleum Conference Calgary, Canada, June 13 – 15, 2006.

Krejbjerg, K., Sørensen, H.
A Solution Algorithm for Simulating Hydrate Growth
Fifth International Conference on Gas Hydrates, June 13-16, 2005, Trondheim, Norway

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

Pedersen, K.S., Milter, J.
Phase Equilibrium Between Gas Condensate and Brine at HT/HP Conditions
SPE 90309, SPE ATCE, Houston, TX, September 26-29, 2004

Lindeloff, N., Pedersen, K.S., Rønningsen, H. P., Milter, J.
The Corresponding States Viscosity Model Applied to Heavy Oil Systems
Journal of Canadian Petroleum Technology 43, 2004, pp. 47 – 53.

Pedersen, K.S., Milter J., Sørensen, H.
Cubic Equations of State Applied to HT/HP and Highly Aromatic Fluids
SPE Journal 9, 2004, pp. 186-192

Pedersen, K.S., Rønningsen, H.P.
Influence of Wax Inhibitors on Wax Temperature, Pour Point, and Viscosity of Waxy Crude Oils
Energy and Fuels 17, 2003, pp. 321-328

Pedersen, K.S., Lindeloff, N.
Simulations of Compositional Gradients in Hydrocarbon Reservoirs under the Influence of a Temperature Gradient
SPE 84364, SPE ATCE, Denver, Co. Oct. 5 – 8, 2003

Rasmussen, C.P., Pedersen, K.S.
Challenges in Modeling of Gas Hydrate Phase Equilibria
4th International Conference on Gas Hydrates, Yokohama, May 19-23, 2002

Sørensen, H., Pedersen, K.S., Christensen, P.L.
Modeling of Gas Solubility in Brine
Organic Geochemistry 33, 2002, pp. 635-642

Lindeloff, N., Krejbjerg, K.
A Compositional Model Simulating Wax Deposition in Pipeline Systems
Energy and Fuels, 16, 2002, pp. 892-903

Lindeloff, N., Krejbjerg, K.
Compositional Simulation of Wax Deposition in Pipelines: Examples of Application
Multiphase ’01, June 13-15, 2001, Cannes, France

Pedersen, K.S., Milter, J., Rasmussen, C.P.
Mutual Solubility of Water and a Reservoir Fluid at High Temperatures and Pressures. Experimental and Simulated data
Fluid Phase Equilibria 189, 85-97, 2001

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


Rydahl, A.K., Sørensen, H.
Coupling PVT Software with Multiphase Meters
1st North American Conference on Multiphase Technology, Banff, Canada, June, 2000

Pedersen, K.S., Rønningsen, H.P.
Effect of Precipitated Wax on Viscosity – a Model for Predicting the non-Newtonian Viscosity of Crude Oils
Energy and Fuels 14, 2000, pp. 43-51

Madsen, J., Pedersen, K. S., Michelsen, M.L.
Modeling of Structure H Hydrates using a Langmuir Adsorption Model
Ind. Eng. Chem. Res. 39, 2000, 1111-1114

Christensen, P.L.
Regression to Experimental PVT data
Journal of Canadian Petroleum Technology, 38, 1999, pp. 1-9

Aplin, A.C., Macleod, G., Larter, S. R., Pedersen, K.S., Sørensen, H., Booth, T.
Combined use of confocal laser scanning microscopy and PVT simulation for estimating the composition and physical properties of petroleum in fluid inclusions
Marine and Petroleum Geology 16, 1999, pp. 97-110

Rygg, O.B., Rydahl, A.K. and Rønningsen, H.P.
Wax deposition in offshore pipeline systems
1st North American Conference on Multiphase technology, Banff, Canada, June 1998.

Rønningsen, H.P., Sømme, B., Pedersen, K.S.
An Improved Thermodynamic Model for Wax Precipitation: Experimental Foundation and Application
Multiphase 97 Conference, June 18-20, 1997, Cannes, France.

Rydahl, A., Pedersen, K.S., Hjermstad, H.P.
Modelling of Live Oil Asphaltene Precipitation
AIChE Spring National Meeting, March 9-13, 1997, Houston, Tx, USA.

Pedersen, K.S., Michelsen, M.L., Fredheim, A.O
Phase Equilibrium Calculations for Unprocessed Well Streams Containing Hydrate Inhibitors
Fluid Phase Equilibria 126, 1996, pp. 13-28.

Pedersen, K.S., Michelsen, M.L.
Letter to the editor, AIChE J. May 1996 about Galeana et al., Thermodynamics of Wax Precipitation in Petroleum Mixtures
AIChE J 42, 1996, pp. 238-242.

Pedersen, K.S.
Prediction of Cloud Point Temperatures and Amount of Wax Precipitation
SPE Production & Facilities, February 1995, pp. 46-49

Kristensen J.N., Christensen, P.L., Pedersen, K.S., and Skovborg, P.,
A Combined Soave-Redlich-Kwong and NRTL Equation of State for Calculating the Distribution of Methanol between Water and Hydrocarbon Phases
Fluid Phase Equilibria 82, 1993, pp. 199-206

Skovborg P., Ng, H.J., Rasmussen, P., Mohn, U.,
Measurement of induction times for the formation of methane and ethane gas hydrates
Chem. Eng. Sci. 48, 1993, pp. 445-453.

Pedersen, K.S., Blilie, A.L., Meisingset, K.K.,
PVT-Calculations on Petroleum Reservoir Fluids Using Measured and Estimated Compositional Data for the Plus-Fraction
Ind. Eng. Chem. Res. 31, 1992, pp. 1378-1384.

Guo, T. M., Du, L.G., Fredenslund, Aa., Pedersen, K.S.
Application of the Du-Guo and SRK Equations of State to Predict the Phase Behavior of Chinese Reservoir Fluids
SPE Reservoir Engineering, August 1991, pp. 379-388

Skovborg, P., Rønningsen, H.P., Pedersen, K.S.
Wax Precipitation from North Sea Crude Oils. 4. Thermodynamic Modeling
Energy and Fuels 5, 1991, pp. 924-932.


Pedersen, K.S., Fredenslund, Aa., Thomassen, P.
Properties of Oils and Natural Gases
Gulf Publishing Inc., Houston, 1989.

Pedersen, K.S., Thomassen, P., Fredenslund, Aa.
Characterization of Gas Condensate Mixtures
Advances in Thermodynamics 1, 1989, pp. 137-152.

Pedersen, K.S., Lund, T., Fredenslund, Aa.
Surface Tension of Petroleum Mixtures
Journal of Canadian Petroleum Technology 28, 1989, pp. 118-123.

Pedersen, K.S., Thomassen, P., Fredenslund, Aa.,
On the Dangers of Tuning Equations of State Parameters
Chem. Eng. Sci. 43, 1988, pp. 269-278.

Hansen, J.H., Rønningsen, H.P., Pedersen, K.S., Fredenslund, Aa
A Thermodynamic Model for Predicting Wax Formation in Crude Oils
AIChE Journal 34, 1988, pp. 1937-1942.

Pedersen, K.S., Fredenslund, Aa.
An Improved Corresponding States Model for the Prediction of Oil and Gas Viscosities and Thermal Conductivities
Chem. Eng. Sci. 42, 1987, pp. 182-186.

Pedersen, K.S., Fjellerup, J., Thomassen, P., Fredenslund, Aa.
Studies of Gas Injection into Oil Reservoirs by a Cell-to-Cell Simulation Model
SPE 15599, SPE ATCE, New Orleans, LA, October 5-8, 1986.

Pedersen, K.S., Thomassen, P., Fredenslund, Aa.
Thermodynamics of Petroleum Mixtures Containing Heavy Hydrocarbons. 3. Efficient Flash Calculation Procedures Using the SRK Equation of State
Ind. Eng. Chem. Process Des. Dev. 24, 1985, pp. 948-954.

Pedersen, K.S., Fredenslund, Aa., Christensen, P.L., Thomassen, P.
Viscosity of Crude Oil
Chem. Eng. Sci. 39, 1984, pp. 1011-1016.

Pedersen, K.S., Thomassen, P., Fredenslund, Aa.
Thermodynamics of Petroleum Mixtures Containing Heavy Hydrocarbons. 1. Phase Envelope Calculations by Use of the Soave-Redlich-Kwong Equation of State
Ind. Eng. Chem. Process Des. Dev. 23, 1984, pp. 163-170.

Pedersen, K.S., Thomassen, P., Fredenslund, Aa.
Thermodynamics of Petroleum Mixtures Containing Heavy Hydrocarbons. 2. Flash and PVT Calculations with the SRK Equation of State
Ind. Eng. Chem.Process Des. Dev. 23, 1984, pp. 566-573.

Pedersen, K.S., Thomassen, P., Fredenslund, Aa.
SRK-EOS Calculation for Crude Oils
Fluid Phase Equilibria 14, 1983, pp. 209-218.