Block 38, located in the Dhofar Region of southwest Oman, was awarded to Frontier in October 2012. The block covers approximately 17,425 square kilometers and is bounded to the west by the Republic of Yemen, to the north is the Rub Al Khali Basin and the Kingdom of Saudia Arabia and to the east lies the prolific South Oman Salt basin (SOSB). The Bock is separated from the highly productive South Oman Salt Basin Basin (SOSB by a north-east trending linear basement feature known as the Ghudun-Khasfah High.
Based on data from previous exploration efforts and the results of an independent evaluation by SLR Consulting Frontier believes that this Block contains an untested salt basin with exploration potential analogous to the other proven salt basins of Oman, particularly the SOSB that lies approximately 50 kilomteres to the east.
Exploration targets include carbonate stringers embedded in the Ara group salts lying a depths of between 3000 and 5000 meters. Secondary targets are within the shallowers Haima group which had minor oil shows during previous drilling and the deeper Buah Formation which has proven to be gas productive elsewhere in Oman.
Exploration History
Between 1953 several companies, including Dhofar Services petroleum Corporation (DSPC0, Petroleum Development Oman, BP, Phillips and Sinopec undertook exploration programmes to varying degrees. Approximately 4500 kms. of 2D seismic data have been acquired on Block 38. Most of the survey grid is sparse except locally in the north of the block where the grid is 2 km. x 2km. Gravity and aeromagnetic data are also available. Microbial prospecting has also been undertaken along certain lines.
Three exploratory wells have been drilled on the Block. These wells are summarized below:
Ahboot #1
The most southerly well on this block is Ahboot-1 which was drilled by Cities Service in 1959, The well encountered 1470 ft. of Tertiary sediments, 402 ft. of Lower Cretaceous, and 2099 ft. of Ordovician. The total depth in the Mahatta Humaid formation (Ordovician) was 3971 ft. No shows were reported. One drill- stem test in the Cretaceous recovered 760 ft. of drilling mud. This test was inconclusive.
Wadi Ghudun -1
The Ghudun-1 well was drilled in 1964 by John Mecom and Pure Oil, on a surface high north of Ahboot-1. The well encountered 1356 ft. of Tertiary sediments, 818 ft. of Cretaceous, 1504 ft. of Carboniferous and Permian, 4579 ft. of Ordovician and Devonian and penetrated 500 ft. of Basement. The total depth, in a basement igneous complex of andesite, granodiorite and quartzite, was 8757 ft. No shows were reported. One drill-stem test in the Haushi produced sulfurous water.
Al Darmaa-1
The Al Dharma-1 well was drilled by a consortium ( Phillips, Maersk, Berkerly) led by Phillips Petroleum in 2001. The well was drilled to a total depth of 10,667 ft.
Hydrocarbon Potential
The main play concept is the deep, unconventional oil play of the Ara Group with emphasis on the intra-salt Athel silicilyte and the Carbonate stringer play located at depths between 3 and 6 kms. similar to that established in the South Oman Salt Basin to the east. These stringers are intra-cratonic, marine fed deposited in a restricted setting the resulted in an evaporitic giant with large scale evaporate/carbonate sequences. The combination of source and reservoir rock deposited within a single depositional cycle and then trapped and sealed by salt resulted in a self contained hydrocarbon system. Additional play is the Pre-salt play of carbonates and clastics within the Nafun and Abu Mahara groups.
There is also the Haima clastics play where up to five reservoir-seal pairs may be present within the Haima Supergroup. The Andam Formation contains the Barik Sandstone Member and below this lies Mahwis and Amin Formations. Reservoir sandstones of these formations were deposited in a continental to marginal marine environment. The Barik Sandstone is fine grained with intercalated with thin silts and shales. Source rocks are prognosed to be within the upper Precambrian to Lowewr Cambrian, Nafun and Ara Groups. These source rock intervals are widespread across the salt basins of Oman and can reach thicknesses from tens to hundreds of meters and TOC values that range from 1.5 - 5%.
Jeza-Qamar Basin
The unexplored Jeza-Qamar Basin lies in the southwest corner of Block 38 and extends into Oman from Yemen. (Fig 2). The basin contains sediments ranging in age from Jurassic to Cretaceous however no Jurassic sediments are known on the Omani side. The sediments in Oman, ranging in age from Early Cretaceous (Barremian) to Late Cretaceous( Maastrichtian) onlap the against the uplifted basin margins which are called the Fartaq High to the west and the Marbat High to the east and are well exposed in the Dhofar mountains of Jabal Samhan , located nort of Marbat, Jabal Qara, north of Salalah and Jabal Qamar, north of Rakhyout extending into the Yemeni border. Several unconformities are present within the Cretaceous section which consist of six formation including the Qishn, Kharfor, Dhalqut, Qitqawt, Samhan and Sharwayn.
There is a close correlation between the sedimentary section of this basin and the hydrocarbon producing sediments in the region however very liitle exploration has taken place here possibly due to previous exploration results and the lack of understanding of its geologic history.
