oa Exploring the Ordovician Ghudun Play in North Oman: Challenges and Way Forward

As conventional hydrocarbon plays have become highly mature after more than 50 years of<br>exploration, Petroleum Development Oman (PDO) is increasingly focusing towards un-conventional<br>plays. The Ghudun stratigraphic play is one example where Ordovician Ghudun sandstone reservoirs<br>are sealed, vertically and laterally, by shales of the overlying Ordovician-Silurian Safiq Group. The<br>Safiq Group consists of three member formations namely Saih Nihayda, Hasirah and Sahmah, listed<br>from old to young.<br>Evaluation of the play was initiated with studies reviewing serendipitous Ghudun discoveries and<br>subsurface data gathered over several decades. From these studies emerged the Ghudun stratigraphic<br>play with several sub-play segments. The risks and uncertainties associated with the play are spatially<br>variable, reflecting the various play segments, spans multiple geological domains and has variable oil<br>and gas charge potential. The main challenge associated with this play is the difficulty in mapping Top<br>Ghudun on seismic data (due to low impedance contrasts). This challenge forced PDO to seek<br>alternative technologies such as gravity modeling and advanced seismic techniques e.g. neural net<br>approaches to effectively unlock the play potential.<br>The play segment which is described is the Safiq Canyon Play Segment where canyons have eroded<br>most of Saih Nihayda and some part of Upper Ghudun and are sealed by the Safiq shales. A cluster of<br>prospects has been matured and a well was drilled in 2008. The drilling results have been<br>disappointing but they highlighted risks that were not originally captured and technologies have been<br>recognized which can mitigate these risks. The drilling results have resulted in updating our<br>understanding of the Ghudun play.