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Our solution required:

Surface production streams were analysed for both hydrocarbons and sulphur species and mathematically recombined the give the wellstream composition. Concentrations above and below the producing zone were predicted using equation of state modelling incorporating the effect of gravity.

Lateral variations in sulphur were inferred from geochemical studies. Representative zones were then modelled under depletion to predict the equilibrium gas thiol concentrations during future production. The results showed that concentrations would not significantly increase with time and so no additional costs for special steels would be required.

Determination of Contaminant Distributions from Gravitational Equilibrium

The Problem

Trimethylarsine was detected in minute amounts in an untreated reservoir gas, which also produced some hydrocarbon liquids during processing. The origins of the gas, how processing would affect trimethylarsine concentrations, and potential remediation routes were urgently required.


Petrophase determined the biological origin of the contaminant and reported on the toxicity and potential effect on catalysts.  The trimethylarsine concentrations at various stages during processing were modelled using an equation of state model incorporating the appropriate properties of trimethylarsine. This model was used to see the effects of the partitioning of trimethylarsine in the sea line and through production to export streams. Thus the effect of different processing conditions on the export compositions could be assessed. The levels predicted from the model, which were later confirmed by measurement, showed that processing alone was sufficient to keep streams within specification and to safe levels.