Abstract
Environment acceptable modified natural macromolecule based drilling fluid is mainly composed of shale inhibitor agent IND30, fluid loss control agent NAT20, bloomless white asphalt NFA-25 and dry powder of polyalcohols PGCS-1, which are biodegradable and environment acceptable. Results of rheological property tests of based mud, IND30 mud, NAT20 mud, NFA-25 mud and environment acceptable modified natural macromolecule based drilling fluid provide us with the best of dosage of each component and confirm that the drilling fluid system meets requirements of petroleum drilling. Other experiments indicate that environment acceptable modified natural macromolecule based drilling fluid has five merits. Firstly, it can bear a high temperature of 140□. Secondly, it has very good anti-contamination ability. Thirdly, inhibit ability of the system is very strong. Fourthly, it can control formation damage. Last but not least, both of the drilling fluid and the basic components are environment acceptable. Field applications of environment acceptable modified natural macromolecule based drilling fluid indicate that not only did the drilling fluid solve a series of complex problems it did not disturb other works such as well logging, casing and production. What's more, it is a kind of environment acceptable drilling fluid that can be used both on dryland operation and in marine drilling for different well types.
