Natih Unconventional Play: Reviving a Dormant Play

By

 Omar S. Al-Ja'aidi¹, Hisham. A. Siyabi¹, Yaqoob. M. Al-Sa'adi²

(1) Petroleum Development Oman, Muscat, Oman (2) Petroleum development Oman, Muscat, Oman

 Stratigraphic opportunities of the Late Albian to Early Turonian Natih Formation of North Oman have been recognized since the early 1960s. However, throughout the years, the Natih unconventional play has remained risky. The risks were mainly attributed to limited 2D seismic data and a poor understanding of the charge system.

The potential for stratigraphic trapping within the Natih has been re-assessed through:

1. the utilization of 2D and 3D seismic data, 2. the construction of common risk segment maps, 3. the evaluation of recorded hydrocarbon shows, 4. fieldwork.

The following stratigraphic exploration opportunities have been addressed:

1. Combined 2D and 3D seismic data from North Oman display a complex system of channels at the top of the Natih A. The channels range from wide, fairly straight and slightly sinuous to narrow, highly sinuous channels that show meander loops and cutoffs. The stratigraphic traps are largely dependent on the infilling of these channels, incised into the Natih A and running perpendicular to the regional dip, with mud and shales.

2. Reefal buildups and mounds along the prograding platform edges of a Natih E intra-shelf basin, occurring in the area between the Fahud and Ghaba Salt Basins. These structures are fully surrounded by intra-shelf basinal facies, which provide top and lateral seals.

3. Truncated Natih intervals are recognised in NW Oman. Reservoir intervals occur as truncated carbonate wedges with intra-formational lime mudstone and shales acting as seat seals and the base Tertiary Shammar shale as top seal.

The availability of 3D seismic data coupled with a better understanding of the charge system is expected to revive the Natih unconventional play.