f Underbalanced Drilling as a Tool to Test Tight Gas Plays: An Example from the Empty Quarter, Saudi Arabia

Underbalanced drilling was implemented in one of SRAK’s exploration wells, Zaynan-2, as the deeper Palaeozoic reservoirs in the Rub’ al Khali are known to be commonly tight and susceptible to near-wellbore formation impairment during conventional drilling. UBD offered a possible solution for reservoir evaluation and demonstrating any possible flow. In other prospects, previous conventional drilling, stimulation and well clean-up had typically failed to unambiguously characterize pay and produce hydrocarbons to surface.