Abstract

Annular gas migration after cementation is a major problem in the oil industry. The resultant hazard and expense made the development of a solution a priority. This paper describes the gas migration phenomenon, and presents a solution that has been applied with success in various parts of the world. The described cement systems does not block the gas flow in the formation, but creates an impermeable barrier within the cement matrix that will impede any annular gas movement. The mechanism is safe and the surface operation does not differ from any other common cementing job. Emphasis is put on the necessity of good cement placement techniques to achieve adequate mud removal and the physical properties of the system are discussed.

Shown are the different rheological behaviors that can be achieved at various density and temperature ranges where the system has been successfully applied. Case histories are presented to illustrate the results obtained in Indonesia with this new cement.