Inhibitive water-based drilling fluid system and method for drilling sands and other water-sensitive formations

摘要

The use of a high and low molecular weight non-ionic polyacrylamide, one or more long chain alcohol and poly anionic cellulose to enhance the flocculation of an aqueous based fluid. The high-molecular weight non-ionic polyacrylamide has a molecular weight in the range of 4 million to 15 million, the low-molecular weight non-ionic polyacrylamide has a molecular weight in the range 500,000 to 2 million and the one or more long chain alcohols have a molecular weight in the range of 200 to 500. The use comprises adding to said fluid the high and low molecular weight non-ionic polyacrylamide, the one or more long chain alcohols and the poly anionic cellulose.