Underbalanced Drilling in Depleted Formation Achieves Great Success: A Case Study

The drilling technologies have evolved over the years. The prime reasons for the advancements in these technologies are the ever increasing demand for energy and the increase in ‘energy price’. Underbalanced drilling (UBD) is gaining popularity as a drilling methodology to overcome some of the problems encountered in conventional overbalanced drilling. UBD was initially adopted for resolving drilling problems; it is defined as a drilling operation where the pressure of the circulating drilling fluid is lower than the pore pressure of the target formation of interest. By far, it has also been proved that the advantages of underbalanced drilling are most evident in depleted reservoirs. Well Parsi 70 was the 3rd well of National Iranian Drilling Company (NIDC) UBD campaign in Parsi oil field. Well PR 70 is the first well that produced while drilling.