UDL product is made fromspecial surfactants, cationic shale-control agents and asphalt of different softening point by use of special technology. The micron asphalt particles carrying cationic electric charge can adsorb on clay grain, with which form mud cake together, enhancing mud cake quality. The asphalt particle and cationic shale-control agents can also invade micro-fracture of wellbore and engender adsorption and aggregation. And hence, UDL woks the function of pl ing, bridge linking, anti-swelling, anti-sloughing, filtrate loss reduction and formation damage control. UDL can be used in any kind of water-base drilling fluid and can be suitable to any type well except exploring well in case it exert bad influence on fluorescence logging.
