Abstract: The circulation loss may occure usually in cementing in the formations of low pressure, leakage zones or fractured formation, so it will pollute the pay zones, reduce the penetration rate and increase the drilling cost. After analyzing many cementing practices, it is known that foamed cement is the Ultralightweight cement and has been used successfully as necessary technology of air drilling ay home and aboard. Because of the compressible gas in the foamed cement and gaseous phase parameters determined by the different pressure and temperature, it can′t use the conventional cementing theory to calculate. On the basis of the foamed cement physical model, the mathematical model using hydraulics and thermodynamics law is established. And the operation parameters calculation method suitable for foamed cement cementing is formed after analyzing the changing character of foamed cement density and pressure. The modeling concept and solving method are presented, meanwhile the case study shows the method is valid and viable in the actual cementing.

Key words: foamed cement, circulation loss, cementing, mechanical aeration, operation parameter