Petroleum Geology and Hydrocarbon Potential of the Guban Basin, Northern Somaliland

Abstract

The Guban Basin is a NW-SE trending Mesozoic-Tertiary rift basin located in northern Somaliland (NW Somalia) at the southern coast of the Gulf of Aden. Only seven exploration wells have been drilled in the basin, making it one of the least explored basins in the Horn of Africa --southern Arabia region. Most of these wells encountered source, reservoir and seal rocks. However, the wells were based on poorly understood subsurface geology and were located in complex structural areas.The Guban Basin is composed of a series of on-and offshore sub-basins which cover areas of 100s to 1000s of sq. km and which contain more than 3000 m of sedimentary section. Seismic, gravity, well, outcrop and geochemical data are used in this study to investigate the petroleum systems in the basin. The basin contains mature source rocks with adequate levels of organic carbon together with a variety of reservoir rocks. The principal exploration play is the Mesozoic petroleum system with mature source rocks (Upper Jurassic Gahodleh and Daghani shales) and reservoirs of Upper Jurassic to Miocene age. Maturity data suggest that maximum maturity was achieved prior to Oligocene rift-associated uplift and unroofing. Renewed charge may have commenced during post-Oligocene-Miocene rifting as a result of the increased heat flows and the increased depth of burial of the Upper Jurassic source rocks in localised depocentres. The syn-rift Oligocene-Miocene acts as a secondary objective owing to its low maturity except possibly in localised offshore sub-basins. Seals include various shale intervals some of which are also source rocks, and the Lower Eocene evaporites of the Taleh Anhydrite constitute an effective regional seal. Traps are provided by drag and rollover anticlines associated with tilted fault blocks. However, basaltic volcanism and trap breaching as a consequence of the Afar plume and Oligocene-Miocene rifting of the Gulf of Aden cause considerable exploration risk in the Guban Basin.

Petroleum Geology of the Nogal Basin and Surrounding Area, Northern Somalia: Part 1, Stratigraphy and Tectonic Evolution

“…15a). The group correlates well with other Gulf of Aden depocentres in northern Somalia, such as those in the Daban Basin (Ali, 2015). Deposition of the Nogal Group was controlled by growth faults related to the development of the Gulf of Aden rifting event (Figs 9-11).…”

“…They showed that basin fills in general can be divided into five stratigraphic sequences that range in age from Late Jurassic to Neogene. In addition, Ali (2015) investigated the petroleum geology and hydrocarbon potential of the Mesozoic-Neogene Guban rift basin, which is located along the southern coast of the Gulf of Aden and NW of the Nogal Basin.…”

Petroleum Geology of the Nogal Basin and Surrounding Area, Northern Somalia, Part 2: Hydrocarbon Potential

“…Source rock analyses made on samples from the Nogal-1, Kalis-1, Faro Hills-1, Las Anod-1, Burhisso-1 and Buran-1 wells ( Table 2) were used as input for the petroleum systems modelling. In addition, source rock properties measured from Upper Jurassic outcrops in the Guban Basin were used as input for the Bihendula source model (Ali, 2006;Ali, 2015). PetroMod petroleum systems modelling software was used to simulate the generation, migration and accumulation of hydrocarbons in the basin.…”

“…The basin is bounded by the escarpment of the northern Somalia plateau to the south and by the Gulf of Aden in the north. The study concluded that mature source rocks of Late Jurassic age (Gahodleh and Daghani shales) together with various reservoir rocks are present in the basin (Ali, 2015). Furthermore, Ali and Watts (2016) reported that the sedimentary succession of the Guban Basin is similar to that in the Nogal Basin (Fig.…”

“…These rift phases controlled the structures, sedimentary sequences and development of petroleum systems in basins in northern Somalia. Ali (2015) investigated the petroleum geology and hydrocarbon potential of the Guban Basin, which is part of the rifted continental margin along the southern coast of the Gulf of Aden. The basin is bounded by the escarpment of the northern Somalia plateau to the south and by the Gulf of Aden in the north.…”