The penetration rates of invert oil mud systems in Mancos Shale have been measured using the full-scale wellbore simulator at the Drilling Research Laboratory. Experimental parameters were 1.) weight material type - high specific gravity (ilmenite) vs conventional (barite); 2.) fluid formulation - low colloid type (relaxed filtrate) vs conventional (low filtrate) and 3.) bit type - synthetic diamond insert blank vs conventional (three-cone roller). In addition to laboratory data, field case history data for corresponding systems have been studied. Maximum penetration rates were observed for the minimum solids system, especially when used in conjunction with the synthetic diamond insert bit.

The penetration rates of invert oil mud systems in Mancos Shale have been measured using the full-scale wellbore simulator at the Drilling Research Laboratory. Experimental parameters were