Drilling fluid additive and method

Abstract

A method is provided for drilling a wellbore including the steps of: providing a drilling mud comprising a primary amine; circulating the drilling mud while the wellbore is being drilled wherein the primary amine is incorporated into a filter cake deposited on the wellbore wall as the wellbore is being drilled; and removing at least a portion of the filter cake after the wellbore is drilled by circulating fluid into the wellbore a composition comprising nitrous acid. The invention also includes the drilling fluid containing a solid component that generates gas from within the filter cake upon contact with a component that causes the solid component to generate gas. In some embodiments, the solid component is a primary amine grafted to a polymer that is not soluble in the drilling fluid composition such as a starch.

Dependencies are inferred from the claim text.