Tectonic controls upon drainage basin development, river channel migration and alluvial architecture: implications for hydrocarbon reservoir development and characterization

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Abstract
Hydrocarbon reservoirs of fluviatile origin are the product of a number of geological processes acting on a variety of scales. Reservoir characterization must be approached holistically in order to understand these processes fully. Tectonic style produces the macro-architectural framework and influences the behaviour of rivers at a mesoarchitectural scale. Tectonics controls the magnitude, position and development of drainage basins and thus, with climate and local geology, controls the flux of sediment fed into any fluviatile system. Migration of normal faulting may lead to the initiation of drainage basins in previously depositional areas, erosion and reworking thus enhancing reservoir quality. Sediment may be introduced as axial or transverse fluxes. Deducing these contributions in ancient basins establishes basin geometry and the basis for reservoir characterization. Individual river channels are highly susceptible to gradient changes caused by tectonic tilting. This causes slow channel belt migration, incision or sudden diversion (avulsion), depending, in a poorly known way, upon the magnitude of the gradients involved. The alluvial architecture of both tilt-block and growth fold basins is discussed, the latter illustrated by recent studies in the Southern North Sea Basin.