Abstract
In turbidite deposits, production history analysis indicates that fluid flow behavior is often more complex than expected. The cause is commonly linked to the presence of fine-scale sedimentary heterogeneities within the reservoir particularly in the case of turbiditic submarine channel complexes with final channel-filling stages composed of lateral migration deposits usually below seismic resolution.
Depositional patterns recognized as channel migration and aggradation packages from Oligocene and Miocene series in the Congo Basin, offshore Congo, exhibit different dynamic responses when modeled in a reservoir simulator.
They are related to the various preservation rates of bank collapse sediments within isolated channel bodies. The proposed workflow comprises 3D sedimentary simulations –, based on geometrical modeling that allow a realistic distribution of elementary channels in the final fairway reservoir model. The individual channel borders, below reservoir grid resolution, are identified as the main heterogeneity, and are used to position transmissibility multipliers.
These elementary channels are used as guides for facies and petrophysical modeling. The proportions and distributions of the different parameters are controlled by well data and sedimentary concepts and architectures. The channels, localized in the main fairway, are grouped per sequence. The main dynamic heterogeneities can be addressed either by the sequence boundaries or by elementary channels borders.
Channel sequences and elementary channels were integrated in Eclipse simulations to history match the DST, with transmissibility reduction between sequences, and between elementary channels.
Multipliers that were used to match the DST are extended along the fairway and lead to a conceptual model, where the variation of channel "skin" is a function of its sinuosity and migration type. Transmissibilities are either reduced in meander zones dominated by lateral channel stacking or preserved in "linear zones" dominated by vertical channel stacking.
