The Yumna Field is a tilted fault block in the shallow offshore part of the Masirah Graben, a northeast–southwest trending basin along the Oman coast. The basin seems to have been historically overlooked, perhaps on grounds of materiality and challenges posed by the thrusted ophiolitic mélange in the shallow section. The field was discovered by the GA South-1 well, drilled by Masirah in 2014. The reservoir is the Upper Cretaceous Lower Aruma Formation, a transgressive sheet sand. While thickness is a modest 10–20m, the sand has excellent porosities of 21–24% and 2 Darcy permeability.
Both Yumna-2 and Yumna-3 have been completed as producers and a production rate of 20,000 bopd has exceeded expectations. However, the lateral extent of the good quality reservoir is now in question, as poor reservoir quality is stated as the reason for lack of commercial hydrocarbons at Zakhera. Near the Yumna Field, sand quality is high, as proven by Yumna North-1 and East-1, but charge or trapping issues will need to be better understood. Either way, there is still significant potential for Masirah in the block, which covers the greater offshore part of this overlooked basin.
