| 摘要 |
The present invention relates to methods of drilling a wellbore wherein a drill-in fluid is foamed at the drill tool. A method in accordance with the present invention comprises providing a drill-in fluid comprising an aqueous fluid, a foaming agent, a foam stabilizer, a gas generating chemical and an encapsulated activator; introducing the drill-in fluid downhole into a drill string connected to a drill tool; and allowing the drill-in fluid to exit the drill tool where, upon exiting the drill tool, the encapsulated activator is de- capsulated sufficiently to react with the gas generating chemical such that a gas is generated within the drill-in fluid and thus foams the drill-in fluid. |
