Petroleum systems of Oman: Charge timing and risks

After 35 years of exploration, creaming of the conventional plays in Oman i s nearly complete, and consequently, the search has commenced for new, less obvious plays. Many of the new opportunities occur beyond the known hydroc arbon provinces and are considered to have significant charge risks. To def ine these risks, extensive basin modeling studies have been conducted in re cent years. Modeling and empirical data show that Mesozoic and Cenozoic kitchen areas a re restricted to western north Oman, the only areas currently buried at the ir maximum temperature. Large parts of north and central Oman depend on lat eral migration from these kitchens for their charge. Progressive uplift of the east flank and basin inversion since the middle Paleozoic provides favo rable conditions for long-distance migration in the post-Carboniferous inte rval. In central Oman, geochemical tracer molecules (benzocarbazoles) sugge st that a north-south-trending, reactivated basement grain has funneled cha rge up to 300 km southeastward. Charge risks increase in the deeper sequenc e, in which eastward migrating hydrocarbons have to traverse the Ghaba salt basin, a pronounced syncline at depths greater than 3 km. The south Oman s alt basin is currently cool because of shallow depths and hydrodynamic flui d-flow activity. The shallow post-Cambrian reservoirs rely on storage of ea rly (Cambrian-Ordovician) charge by the Ara salt (Cambrian) sequence, follo wed by release of hydrocarbons as the salt edge retreats through time. Basin modeling has outlined the extent of the different petroleum systems a nd provided us with risk maps to guide our next exploration phase. It has r evitalized some of the mature plays, for instance the Gharif Formation, whe re oil exploration is now focused along Late Cretaceous and Tertiary migrat ion paths. Deeper sections are envisaged to have significant scope for gas.