The rheological properties of biodiese and white oil were compared at normal temperature and high temperature in this paper. The ability of biodiesel to inhibit shale expansion was investigated. The results showed that the rheological properties of biodiese were better than white oil. Biodiese also showed better resistance to high temperature and shale expansion. Organo- lignite and vegetable pitch were used to reduce the filtration in biodiesel-based drilling fluids system. The optimum formulation of biodiesel-based drilling fluids was determined by experiments. In order to simulate the contamination of calcium and dry soil, CaSO4·2H2O and sodium-based bentonite were added to the system, and the experimental results showed that the tolerance of biodiesel-based drilling fluids to the contamination of calcium and dry soil is desirable.
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