Method of enhancing drilling fluid performance

A method of drilling in a wellbore comprising:

• a. providing a drill-in fluid comprising an aqueous brine, a foaming agent, a foam stabilizer, a gas generating chemical and an encapsulated activator;
• b. introducing said drill-in fluid downhole into a drill string connected to a drill tool wherein both said gas generating chemical and said encapsulated activator are admixed into said drill-in fluid prior to introduction into said drill string;
• c. allowing said drill-in fluid to exit said drill tool where, upon exiting said drill tool, said encapsulated activator is de-capsulated by shearing action sufficiently to react with said gas generating chemical such that a gas is generated within said drill-in fluid and thus foams said drill-in fluid between said drill tool and said borehole;
• d. circulating the thus formed foamed drill-in fluid into an annulus formed between said wellbore and said drill string such that drill cuttings produced during drilling are carried by said foamed drill-in fluid back to the surface via said annulus;
• e. recovering said foamed drill-in fluid from said annulus at the surface;
• f. defoaming said thus recovered foamed drill-in fluid to form a defoamed drill-in fluid;
• g. admixing said defoamed drill-in fluid with additional amounts of said gas generating agent and additional amounts of said encapsulated activator to form a recirculation drill-in fluid;
• and
• h. recirculating said recirculation drill-in fluid downhole into said drill string to thus repeat steps b through e for said recirculation drill-in fluid.

A method of drilling in a wellbore comprising:

• a. providing a drill-in fluid consisting essentially of an aqueous fluid, a foaming agent, a foam stabilizer, a gas generating chemical and an encapsulated activator;
• b. introducing said drill-in fluid downhole into a drill string connected to a drill tool wherein said aqueous fluid, said foaming agent, said foam stabilizer, said gas generating chemical and said encapsulated activator are admixed into said drill-in fluid prior to introduction into said drill string;
• and
• c. allowing said drill-in fluid to exit said drill tool where, upon exiting said drill tool, said encapsulated activator is de-capsulated sufficiently to react with said gas generating chemical such that a gas is generated within said drill-in fluid and thus foams said drill-in fluid and wherein said drilling is carried out without the use of viscosifiers, fluid loss control additives and bridging agents other than as those functions are carried out by one or more of said aqueous fluid, said foaming agent, said foam stabilizer, said gas generating chemical and said encapsulated activator as present in said thus foamed drill-in fluid.