Experimental study on loss-prevention performance of oil-based drilling fluids

Compared to the water-based drilling fluids, lost circulation is more prone to occur when drilling with oil-based drilling fluids and it is difficult to deal with this problem on the drilling site for lack of high-efficiency lost circulation materials. In order to solve this technical problem, the principles of pressure resistance plugging technology of oil-based drilling fluids was firstly investigated according to the force-chain principle of granular matter mechanics, and rigid bridging particles, elastic packing particles and micro fibers could synergistically form fracture tight sealing zones with strong force-chain network to strengthen the lost circulation prevention ability of oil-based drilling fluids. Based on the principle above, novel loss-prevention materials were finally developed for oil-based drilling fluids by optimizing different plugging agents. Experimental results show that novel loss-prevention materials could be compatible with other components of oil-based drilling fluids. The oil-based drilling fluids with high sealing capacity could be optimized by adding novel loss-prevention materials, and it exhibits good rheological behavior with a low PPT filtration of 11.4 mL and excellent lost circulation prevention ability to strengthen the wellbore while drilling.