Tech Talks

#7: GERG-2008 for Highly Accurate Natural Gas Properties

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 …

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#6: Gas Injection as an Enhanced Recovery Technique for Gas Condensate Reservoir Fluids

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 …

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#5: Separator Corrected Black Oil Properties

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 …

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#3: Compositional Grading

Calsep recently got access to data for the compositional variation with depth in five North Sea reservoirs. All five reservoirs have a gas-oil contact in the interval fluid samples were taken. Figure 1 shows the variation in saturation pressure with depth in two of the reservoirs. The depths are relative to the depth of the …

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#2: How good are the predictions of sound velocity with an equation of state?

It was a major achievement when Peneloux et al in 1982 presented the method for volume correcting a cubic equation of state. It enabled liquid densities to be matched using a cubic equation, which was not possible with the equations in their original form. Prior to that time cubic equations had mainly been used to …

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#1: Huron-Vidal Mixing Rule. A Unique Combination of a Cubic Equation and a GE model

Cubic equations have been an industrial standard in oil industry since the nineteen eighties, but in the original form those equations are unable to handle the mutual solubility between hydrocarbons and aqueous components. Formation water is often produced together with petroleum reservoir fluids and hydrate inhibitors may have to be added to prevent hydrate formation …

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