Abstract:Due to the instability of shale gas horizontal well, oil-based drilling fluid leakage will cause a great economic loss; so the property requirement of oil-based drilling fluid system is higher and higher. In view of the above issues, a new type of strong plugging oil-based drilling fluid system has been developed by orthogonal test; the laboratory tests show that this system has excellent stain resistance, emulsifying stability, low fluid loss, good rheology, moderate viscosity and shear force. By the application of strong plugging oil-based drilling fluid system, well Jiaoye195-1HF shows that the leakage risk and loss cost are greatly reduced compared to well Jiaoye200-1HF which used common drilling fluid and several other wells; in this circumstance, 11 days are saved; this strong plugging drilling fluid system has good application prospect.