Patent ID: 6794340
Filing Date: 2004-09-21
Classification: C09K,Y10S

Abstract:
A method for drilling a borehole in a subterranean formation employing a drill bit, said method comprising:providing a drilling fluid comprising a polymer viscosifier and an encapsulated crosslink activator for crosslinking said polymer viscosifier, introducing said drilling fluid into the borehole; allowing said crosslink activator to become released from said encapsulation after passing through said drill bit; allowing said crosslink activator to cause said polymer to crosslink and increase the viscosity of said drilling fluid; entraining drill cuttings in said drilling fluid; bringing said drill cuttings and said drilling fluid to the surface of the borehole; reducing the viscosity of said drilling fluid; removing said drill cuttings from said drilling fluid; adding encapsulated crosslink activator to said drilling fluid; and returning said drilling fluid to said borehole.