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General Overview
The Nogal Valley and Dharoor Valley Blocks situated in northern Somalia cover the Nogal Basin and the Darin Basin, respectively.
Combined, the two blocks cover a very large area, with the Nogal Valley Block extending over approximately 12,849,479 acres, which encompasses the Nogal Basin. The Dharoor Valley Block extends over an area of 7,166,056 acres, encompassing the entire Darin Basin. These areas are very large and, with only 5 wells drilled, the area remains one of the least explored areas in North Africa.
The Company with their partners Range Resources Limited signed two Production Sharing Agreements (PSA) with the Government of Puntland on January 17th 2007. One covering the Nogal Basin referred to as the Nogal Valley Block and the second covering the Darin Basin referred to as the Dharoor Valley Block. The terms and articles of both agreements are identical as are the value of the work commitments for the exploration phase.
The Nogal Basin covered by the Nogal Valley Block has been identified as having reservoir, source rock and trap potential. International oil and gas companies conducted exploration in the late 1980's in the region. During this exploration phase, a grid of 2D seismic was shot perpendicular to the axis of the rift system in the Nogal Basin. Based on interpreted maps this data shows a number of large, closed, fault-controlled structures.
In addition, surface geology identified a number of oil seeps along the main basin-bounding faults. Several wells drilled on the identified structures encountered numerous oil shows, however, the wells Nogal-1 and Kalis-1 did not reach the main exploration target.
Structural setting NE Somolia |
Generalized Stratigraphy Puntland |
Dharoor and Nogal Valley Blocks Satellite Image |
Geological Review
The most clearly defined basins in Puntland are the Nogal and Darin basins. These large depressions are visible on satellite imagery. The two basins are believed to be part of a failed rift system and are analogous to the prolific Yemen rift system found across the Gulf of Aden. It is thought that the oil reserves found in the Cretaceous and Jurassic sedimentary sequence in Yemen could also be present in similar formations in the northern portion of Somalia, since these two areas were joined approximately 18 million years ago, before the movement of the Indian plate away from the African plate.
The basin fill is extremely thick, with more than 10,000 feet of sediments in some areas. The main target reservoir is the Jurassic-aged sandstones belonging to the Gabredarre Formation. These reservoir sandstones overlie the organic rich shales and marls of the Uarandab Formation, which is thought to be the source rock for the oil seeps observed along the boundary faults. The secondary reservoirs include the deep marine sandstones and shallow marine carbonates belonging to the Upper Cretaceous Gumburo Formation. The marine sandstones of the Jesomma Formation, also Upper Cretaceous in age, are also potential secondary targets. The Jesomma and Gumburo have isopach thicknesses of approximately 1,350 and 2,450 feet, respectively.
The limited information indicates that reservoir quality rocks are present within the Nogal Basin. Of the five wells drilled in the Nogal Basin, images of partial well logs are available for two wells (Nogal 1 and Kalis-1). The drilling reports for these two wells indicated that the Jurassic sandstone targets were not reached but that oil shows were found in some of the shallower sandstones. Nogal --1 was drilled to a depth of 10,736 feet in 1990. Kalis-1 was drilled to at least a depth of 5100 feet in 1990 according to log images. The original plan for Kalis-1 was to drill it to a depth of 14,850 feet.
Surface seeps of oil, as well as oil shows reported in several exploration wells drilled by previous operators in the area, indicate that the source rocks have generated hydrocarbons and that they have migrated through the system. There is not enough data yet to determine if trap formation predates hydrocarbon migration, however.
The indications from the limited number of wells drilled in the basin are that the basin appears to be oil-prone.
Seismic structure maps prepared in the late 1980's by a major oil company and obtained from the Somali Government by the Company show that a number of fault-bounded structures with three way dip closures do exist within the basin. A seismic base map for the basin indicates that approximately 2500 line miles of 2D seismic has been shot representing some 76 seismic lines.
A review of three seismic lines show good structuring in the subsurface with evidence of tilted fault blocks and rollover closure. The structures identified by the major oil company using the seismic data, appear to be quite large with some in excess of 4,000 acres and as large as 14,000 acres. These, combined with the extremely thick section of basin fill, provide multiple horizons in which hydrocarbons can be trapped.
The following table indicates the zone / play types considered for the Nogal Valley Block.
There is insufficient data available at this time for the Dharoor Valley Block to assess the potential within the Darin Basin. The size and proximity to the Nogal Basin suggest that it has had a similar geologic history and, as such, should have similar prospectivity to the Nogal Basin. Future exploration will be needed in order to assess this large area to determine its potential.
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