This paper reports an investigation into the relative performance of scale inhibitors in squeeze treatment in conditions typical of the U.K. North Sea. The methods used were to run laboratory core tests, model the results using the new computer software "SQUEEZE", and compare the outcome with field experience.

At low water throughput rates, satisfactory modelling could be achieved assuming a simple Freundlich isotherm, although there is evidence that this does not represent a true equilibrium situation. At higher water flows, certain products deviate from the Freundlich isotherm. The deviation takes the form of a reduction in the rate at which inhibitor return concentration goes down with time or cumulative production. The return curve may remain at a level almost until depletion. It was not found possible to model these deviated curves.

For a moderate deviation from the isotherm, the decline is arrested at a low scale inhibitor concentration and effective squeeze life is extended. As water throughput increases further, the plateau occurs at a higher concentration and depletion is brought forward. The critical water production rate for a specific product in the cases studied was about 5000 bbl/D.

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