Laboratory Drilling Rate and Filtration Studies Of Emulsion Drilling Fluids

Abstract

Data obtained under controlled test conditions using a microbh drilling machine showed that oil emulsified in water muds may either increase or decrease the drilling rate, depending upon drilling conditions. A low-viscosity oil such as diesel fuel can give driIling rates in limestone almost equal 10 that oj water. Data obtained for water emulsified in oil muds showed little decrease in the drilling rate in water-saturated cores as the water percentage of the mud was increased above the 5-to IO-percent range. Changes in dri![ing rate were found to be dependent upon the oil or water concentration of the mud and upon the type of fortnation driIled. Changes in static filtration on paper (API filtrate) did not correlaw with jilwation while the nmd was circulated across rock.