Underbalanced Drilling
Sand control screens deployed during underbalanced conditions
An innovative inflatable bridge plug system has overcome the challenges of deploying screens in an underbalanced environment
George Arnold and Enrico Suwandi, Baker Oil Tools
Underbalanced drilling (UBD) is now routine in fields with low bottomhole pressures (BHPs), or formations where skin damage may occur due to overbalanced drilling. UBD advantages are offset, however, by more challenging on-site operations brought by continuous pressure at the wellhead.
One requirement is that all tool strings be lubricated into the well before commencing operations. Because the required screen length typically exceeds the lubricating device's length, sand control screens cannot be installed in an underbalanced condition. The option to kill the well before deploying the screens subjects the formation to damaging overbalanced conditions. This dilemma has been resolved with the development of an inflatable deployment system. The new system was used successfully on a recent UBD project in Brunei.
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This article was adapted from a professional society paper for which World Oil was granted the right to print one time only. Therefore, to review the article, you should refer to the actual World Oil magazine in which it originally appeared.
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