Patent ID: 7439210
Filing Date: 2008-10-21
Classification: C09K,Y10S

Abstract:
1. A method of conducting a drilling operation in a subterranean formation having water-sensitive formations, said method comprising employing an aqueous-based drilling fluid comprising high molecular weight non-ionic polyacrylamide and low molecular weight non-ionic polyacrylamide wherein said high molecular weight non-ionic polyacrylamide has a molecular weight in the range of about 4 million to about 15 million and is added in liquid or emulsion form and said low molecular weight non-ionic polyacrylamide has a molecular weight in the range of about 500,000 to about 2 million and is added in powder form, said drilling fluid further comprising one or more long chain alcohols and polyanionic cellulose, such that said drilling fluid retards hydration of said water-sensitive formations while providing lubricity and stable rheological properties for drilling.