|Blocks||ER Nearshore 3B/4B (award pending Govt approval)|
The Nearshore Block 3B/4B is 90-130 km from the shore and covers an area of 960km² in water depths ranging from 300-400m. The block is covered by a sparse grid of multiple vintage 2D seismic data and two wells have been previously drilled. The two wells targeted mainly Albian and Cenomanian turbidite plays. Well AL-1, drilled to a TD of 2271m, and encountered water-bearing sandstones in the Turonian, Cenomanian and Albian, with thicknesses ranging from 10-100m. The AU-1 well, drilled to a TD of 3427m and encountered gas shows and several sandstone reservoir units in the Coniacian, Cenomanian and Albian.
The Ibhubesi gas discovery, in Block 2A, lies immediately north of the Nearshore Block 3B/4B and comprises a series of channel sandstone reservoirs at depths ranging from 3000-3500m. Porosities there range from 16-25% and permeabilities range from 100-200mD. The gas generated from the Aptian marine shale source rocks is of high quality and does not require treatment. This provides encouragement that a similar field may exist within the Nearshore Block.
The structural geology of the Nearshore Block is characterised by an outboard high, containing a Hauterivian capped syn-rift sequence, with a central graben structure located basinward. A relatively thick upper Cretaceous section comprises well-defined and extensive gravity driven fault networks soling out along the Cenomanian shale unit. A second Barremian-Aptian, rift-related, fault network extends from the central graben, and potentially serves as a hydrocarbon conduit to the Late Albian and Early Cenomanian turbidite plays.
Seismic evidence indicates significant reservoir potential to be present in the form of high-amplitude, Albian and Cenomanian/Early Turonian-aged, stratigraphically trapped, basin floor fans. A number of large roll-over structures associated with the slumping/growth faults provide an additional structural trapping element to this play. The pre-Hauterivian syn-rift and Aptian intervals are considered the most likely source rock units, with seismic evidence showing a consistently thick Aptian source rock interval across the licence. Maturity modelling indicates the Aptian is presently within the wet gas generation window, and gas chimneys have been interpreted across the licence.