Accurate correlations exist for the density of pure water. An example is the model of Keyes et al. [1], which is used in PVTsim Nova. Formation water produced together with gas and oil is not pure, but contains dissolved salts, and these salts can have a significant effect on the density. The importance of water …
PVTsim users often ask why we do not assign any importance to Hoffmann plots in the QC module of PVTsim Nova. The idea of a Hoffmann plot is to validate whether a gas and a liquid separator sample are in equilibrium at separator conditions. The below table shows a recombined reservoir fluid composition for a …
Gas condensates are often saturated with water at reservoir conditions. A PVT laboratory will remove the water from a gas condensate sample before carrying out any experimental studies. Measured liquid dropouts in routine CME or CVD experiments are therefore for the water free fluid. The question is often brought up what impact it would have …
#11 Impact of Water on Liquid Dropout from Gas Condensate Read More »
One of the most challenging EoS modeling tasks is to develop a common EoS model for multiple fluids with gas injection. With gas injection being used as an EOR technique for shale fluids, reservoir engineers working with PVT modeling of shale fluids are frequently facing such task. The time spent on developing a common EoS …
#10: Common EoS Model Development for Reservoir Fluids with Gas injection Read More »
Calsep introduced the Cubic Plus Association (CPA) model in PVTsim Nova 2 in 2015. CPA takes into consideration that the thermodynamic properties of polar and non-polar substances of approximately the same molecular weight may deviate substantially because of association between the polar molecules. Water and methane, for example, have approximately the same molecular weight, but …
Knowledge about the reservoir temperature is important for reservoir modeling and field development, but the temperature measured in exploration wells is seldom representative for the reservoir temperature. In a paper presented at SPE ATCE in Dubai in September 2016, Meisingset (Statoil) and Pedersen (Calsep) outline a procedure for determining the reservoir temperature from well test …
Cubic equations of state are the standard in oil industry. They are successful because of their versatility, but users of cubic equations must accept minor deviations from experimental data for most physical properties. For some applications such deviations are unacceptable, one example being volumetric gas calculations. The commercial value of a given volume of gas …
#7: GERG-2008 for Highly Accurate Natural Gas Properties Read More »
Gas injection has for decades been used to enhance oil recovery (EOR). The injected gas keeps the reservoir pressure high and blends with the reservoir fluid to possibly develop a miscible zone that will prevent gas from behind in penetrating and creating a gas break through. The lowest pressure at which a miscible zone can …
#6: Gas Injection as an Enhanced Recovery Technique for Gas Condensate Reservoir Fluids Read More »
PVT reports often lists separator corrected Gas/Oil Ratios (GORs), Gas and Oil Formation Volume Factors (FVFs), etc. together with measured Differential Liberation (DL) and Constant Volume Depletion (CVD) data. The separator corrected black oil properties listed in PVT reports are calculated using empirical correlations. But, what does separator corrected black oil properties stand for and …
With PVTsim Nova 2.0 Calsep is introducing the CPA equation of state as one of the EoS alternatives. The CPA equation of state was presented by Kontogeorgis et al. (1996). CPA stands for Cubic Plus Association, which refers to a classic cubic equation of state with an association term. More specifically CPA combines the SRK …
