Evolution, Routing and Reservoir Characteristics of Submarine Channels in a Structurally Deforming Slope Setting: Deep‐Water Joint Development Zone of Nigeria and São Tomé and Príncipe

Deep‐water slope channels and associated facies are a major part of clastic sediment dispersal system extending from the shelf‐edge to the abyssal plain. The toe‐thrust area of the deep‐water Niger Delta enables the analysis of these channels and their interaction with evolving fault‐controlled sea‐floor topography to be determined. Understanding the relationship between the channels and growing structures is a key element in predicting reservoir distribution and potential trap geometries. This investigation utilises 3D seismic reflection data from the Joint Development Zone of Nigeria and São Tomé and Príncipe (Joint Development Zone [JDZ]) area. Major depositional sequences and coeval faults were mapped to reconstruct the evolution of the thrust‐top basins through time. The relative movement of the thrusts was evaluated using a semi‐quantitative assessment of stratigraphic thinning and onlap patterns. Twenty‐five slope channels, oriented NE–SW were documented throughout the syn‐kinematic interval, showing that structural development was a primary control on their routing. Four interaction patterns are recognised: (i) lateral accretion, (ii) deflection caused by older stratigraphy and structure, (iii) major diversion caused by older stratigraphy and structure, (iv) avulsion. One sea‐floor channel has been mapped in detail to quantify downslope changes in channel‐levee characteristics with structural influence. Although the structure had only minor movement during the deposition of the channel, dramatic changes in the channel dimensions and facies are recorded down the 20 km depositional dip profile: (i) The channel doubles in thickness just downdip of the structural crest as an additional channel complex is preserved in this area, (ii) levees thin at the structural crest but treble in thickness downdip, and (iii) a crevasse splay breaks through the levee where it is thinnest at the structural crest. Potential reservoir‐trap combinations are common as channels cross the thrust–fold structures with two‐way dip along the channel axis and lateral stratigraphic trapping at the channel margins along depositional strike. The youngest channel, imaged on the seafloor, demonstrates how channel axis reservoirs may vary in thickness over short distances due to the evolving structural influence. This is a novel example of the study of channel and structural evolution over 9.3 Ma, within the syn‐kinematic section in the Niger Delta.