The British Petroleum Company, P.l.c.

Clive M Gould

Ian C Callaghan

Christian Weitemeyer

Gotz Koerner

Hans-Ferdi Fink

Hans-Jurgen Patzke

Wojciech Grabowski

Water-insoluble polyoxyalkylene graft copolymers are effective anti-foam agents for reducing foaming in crude oil/gas separators. The copolymers are of formula: ##STR1## wherein R is an ethylene, propylene or butene group or a mixture thereof;

Method for the separation of gas from oil

A method for determining the stability of live foam comprises a sample pressurizing vessel connected to a sample injection chamber leading to a sample cell linked to a reference cell maintained at constant pressure. The link between the sample cell and the reference cell comprises a link fitted with a valve for initially equalizing the pressure between the two and subsequently isolating them. A differential pressure transducer is provided for determining the subsequent change in pressure of the sample with reference to the reference cell as the foam collapses.

Method for determining the stability of foam

Polysiloxanes of specified molecular weight and molecular weight distribution are effective anti-foam agents for reducing foaming in crude oil/gas separators. They are particularly useful in breaking microgas dispersions. The polysiloxanes, preferably polydimethyl siloxane, contain not more than 10% by weight of components of molecular weight 50,000 and lower, at least 15% by weight of components of molecular weight 200,000 and higher and not more than 6% by weight of components of molecular weight 370,000 and higher, molecular weights being expressed as polystyrene equivalent molecular weights.

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Staines, United Kingdom

Clive M Gould