Abstract - Recent progress in understanding the internal architecture of deep-water lobes has benefited from high-resolution seismic data and detailed outcrop studies, and has identified a 4-fold hierarchical geometrical arrangement involving beds, lobe elements, lobes and lobe complexes. Quantitative modelling of the hierarchy is important since understanding different scales of heterogeneity is one of the most critical factors influencing oil production from lobe reservoirs. A novel object-based numerical modelling approach (vbFIFT) is developed aiming not only to reproduce the detailed architecture within lobe complexes, but also to investigate the connectivity of sandstones within and between different hierarchical components. Input parameters include the dimensions, shapes, orientations and sedimentary properties (NTG, Amalgamation Ratios) at each hierarchical level, and are based on published datasets. The model successfully captures the 4-fold hierarchy and many of the characteristic features of deep-water lobes such-as the distal pitchout geometry, dominance of thick sandstone beds in lobe axes alternating with mudstones and thinner-bedded sandstones in lobe fringes, thickening-upward cycles and compensation stacking. A bed-scale correlation of lobes and shallow channels in the Carboniferous Ross Fm. at the eastern end of Kilbaha Bay, western Ireland, provides a real-world example against which to compare the model output. The influence of unknown properties such as the boundary transmissibility at each hierarchical level can be tested by varying the input parameters, and analysis of models can help refine the underlying sedimentary parameterisation. Future work will include analysing the static and dynamic connectivity and exploring what are the key depositional factors controlling reservoir performance and flow behaviour.
Abstract of talk given to:
British Sedimentological Research Group Annual Meeting, University College Dublin, December 2012.