Experimental study of particle transport in a deviated wellbore

The effects of wellbore deviation were examined and analyzed. For a given particle size, the effects of even small deviations from vertical were apparent. The analysis further indicated that both the minimum pressure drop and the optimal annular air velocity are strongly dependent on the angle of the annulus. Utilizing this information, empirical equations were developed to predict the minimum pressure drop and optimum annular air velocity. These equations are based upon the data which can be collected in the field and consequently they may prove helpful in improving air drilling operation in the field.