STRUCTURAL ELEMENTS
Zones of imbricate thrusts occur in the deep offshore Niger Delta. These are well represented in the multi-client seismic data. These compressive structures are typically situated seaward of the zone of shale structures on the upper slope separated by a relatively undeformed zone which exhibits minor thrusting and shale swelling.
The deep water Niger Delta hydrocarbon province encompasses a wide range of syn-depositional structural styles and deep-water sedimentary facies. The region can be broadly separated into four domains. These extend from the zone of shale diapirism on the present-day upper slope, basinward to a zone of relatively minor structuration, a frontal toe-thrust zone, and a zone of frontal deformation on the present-day lower slope and continental rise.
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REGIONAL PROSPECTIVITY
The principal trapping scenarios for each domain are conceptualised on the schematic section. The shale diapirism zone, on the present-day upper slope, has proven prospectivity (Bonga, Aparo and Usan fields). Basinward, the zone of relatively minor structuration, is highly prospective (the Agbami and Akpo fields are just two examples) and extends into the northern blocks of the JDZ.
The frontal toe-thrust zone has much potential as evidenced by DHI’s and flat spots, and the zone of frontal deformation on the present-day lower slope and continental rise is as yet untested.
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Technical Review of Areas on Offer
The Joint Development Zone is between Latitudes 1 and 3 degrees north and longitudes 4 and 8 degrees east in the Gulf of Guinea. It covers an area of 34,548 km2 with water depths ranging from about 1500m in the northern part of the JDZ to over 4000m at its southwestern sector
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A total of 9 blocks situated in the northern sector of the JDZ have been put up for tender in the 2003 JDZ Licensing Round. These blocks cover a total area of 8429 km2 and range in size from 588 km2 to 1723 km2. Water depths for the blocks on offer range from 1500 to 2500m, well within the reaches of today’s technology.
Two major structural regions are present in the Joint Development Zone. The first is a toe thrust zone situated in the northern sector of the area corresponding to the distal parts of the Niger Delta. To the south of this is a second zone of minor structuration underlain by a rift system of Cretaceous age.
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