Oil-based drilling fluids

saturated/under-saturated saltwater drilling fluids were generally introduced to salt/gypsum stratum according to mechanics and physics analysis. But oil-based drilling fluids cannot be applied cosmically because of itself limitation. And accidents and complex situations take place frequently by adopting saturated/under-saturated saltwater drilling fluids. Under acceptable drilling fluids cost condition

hole in salt/gypsum stratum can be stabilized that under-saturated organic salt liquor drilling fluids with proper density can satisfy the condition that formation salts are solved appropriately and keep better drilling fluids inhibition. Two drilling fluids are prepared by organic salt based solution density of 1.30 g/cm3 and 1.36 g/cm3 respectively; and their routine properties

resistance to fouling

and inhibition are evaluated in lab. The conclusion of experiment is that two drilling fluids can achieve the need of drilling salt/gypsum stratum; and the two drilling fluids were applied to Y5-2 well for a field experiment. Results show no fault and less drilling cost compared with other wells in the same structure.