Using underbalanced drilling to reduce invasive formation damage and improve well productivity - An update

Underbalanced drilling (UBD) is becoming increasingly used as a technique t o reduce significant invasive formation damage In vertical and horizontal w ells to improve production rates of oil and gas, and enhance injectivity in gas and water injection situations. UBD may be a technically demanding pro cedure to execute in certain reservoirs and much of the benefit with respec t to mitigation of formation damage may be compromised if the underbalanced drilling operation is not screened, designed and conducted in an appropria te fashion. This paper reviews common formation damage mechanisms which may occur in reservoirs and how, in certain situations, these types of damage may be reduced or eliminated through the appropriate use of underbalanced d rilling technology. Various situations in which underbalanced drilling tech nology may result in potential significant formation damage are also discus sed.