Planning UBD in Horizontal Well to Minimize Formation Damage
By: Ahmed R. Al-Bajalan (March 23, 2015)
This study explores Underbalanced Drilling (UBD), a technique where the effective downhole circulation pressure of the drilling fluid system is kept lower than the existing formation pressure. UBD is often utilized to mitigate issues such as formation damage, which significantly reduces oil and gas productivity, especially in open hole horizontal well sections. This is achieved by using techniques such as aerated drilling and foam drilling that rely on low drilling density.
The paper underscores the importance of careful reservoir candidate selection for successful UBD implementation and high profitability. Furthermore, it highlights the significance of accurate estimation of influx volume and produced fluid rates for appropriately sizing and designing surface equipment like separators and reserve tanks. The project proposes a mathematical model based on rigorous reservoir borehole-cross flow to determine the influx volume during UBD and to investigate the behavior of aerated and foam drilling fluid during UBD operations.