Characterization and Prevention of Formation Damage During Horizontal Drilling.

Abstract

Summary The effect of various factors on the productivity of horizontal wells was quantitatively analyzed. The results show that formation damage is an important factor affecting productivity for the low-permeable sandstone formations studied. The effect of formation damage for a horizontal well on production rate is consistently much higher than that for a vertical well drilled in the same formation. The design criteria, formulations, properties, and applications of three low-damaging drilling muds were discussed. It was observed that the three fluids provided excellent formation protection with much lower skin factors and much larger percentages of regained permeability as compared with other commonly used drilling muds. The oil production rates of most horizontal wells are three to five times higher than that of their adjacent vertical wells, which is highly related to the effective prevention of formation damage.