OIL-BASED DRILLING FLUID COMPRISING A NON-POLLUTING EMULSIFYING SYSTEM WHICH CAN BE USED FOR ANY BASE OIL AND WHICH IS STABLE IN RESPECT OF GAS HYDRATES FORMATION

摘要

The invention relates to an oil-based drilling fluid which is stable regardless of the base oil used, which is not environmentally hazardous and which is suitable for offshore drilling and, in particular, deep offshore drilling. The inventive fluid comprises a non-polluting emulsifying system containing at least one ester which is associated with a nonionic surface active agent of the polymerised carboxylic acid type (dimer and/or trimer). Oil-based drilling fluids comprising one such system, owing to the production of very stable invert emulsions, can also be used in offshore drilling conditions where gas hydrates can form.