عنوان مقاله [English]
In this study, using the results of performed shale formation Characterizatins and the history of drilling in Iranian oil fields, an environmentally friendly water based drilling fluid is designed to replace the oil based drilling fluids. This drilling fluid has desirable properties in drilling water sensitive formations. New drilling fluid additives including shale inhibitors, new polymers and sized solid particles have been used to prepare this new drilling fluid. The most important properties of this new drilling fluid are controlling the mud filtrate and pressure invasion to the formation, clay mineral alteration and activity reduction, improvement of the integrity of drilling cuttings, reduction in formation damage, stability at high temperatures, stability in acidity changes and the compatibility by drilling fluids dilution during drilling operation. The lubricity and shale cuttings recovery of this new drilling fluid are better than those of other similar water based drilling fluids. Replacing this drilling fluid by oil based drilling fluids in drilling industry will be a great means to protect the environment and drilling personnel in addition to being economically advantageous.